Magnesium oxide board based on bamboo filament filling and preparation process thereof

Abstract

The invention discloses a magnesium oxide board based on bamboo filament filling and a preparation process thereof, and belongs to the technical field of light building materials, the magnesium oxide board comprises modified bamboo filaments, modified diatomite, acetylated modified starch, prepared premixed slurry and bamboo filament magnesium oxysulfate cement composite slurry. And mold closing and hot pressing, overlapping, mold locking, curing and curing, drying, cutting and polishing are carried out. The bamboo filaments, the modified starch and the modified diatomite synergistically optimize the internal filling structure, so that the deformation risk in the use process of the board is greatly reduced, the structural form can be kept stable even if the board bears external force for a long time, and the problem of local looseness or overall deformation caused by poor material combination is avoided. The sectional type hot pressing technology enables the compactness of materials in the plate to be uniform, the local impact resistance is strengthened, instant acting force brought by concentrated loads can be resisted, and the overall uniform bearing performance is improved.

Description

Technical Field

[0001] This invention relates to the field of lightweight building materials technology, specifically to a magnesium oxide board based on bamboo fiber filling and its preparation process. Background Technology

[0002] In recent years, with the continuous rise in labor costs, the market demand for prefabricated housing has been increasing due to its advantages such as convenient construction and high efficiency. This has led to the continuous expansion of the market size for floor decking used in prefabricated housing. Magnesium oxide panels, with their lightweight properties, have a large demand in building decoration, component manufacturing, and other scenarios.

[0003] The existing magnesium oxide boards lack overall structural stability. Under external forces or during long-term use, they are prone to deformation, cracking, and other quality defects, which not only affect the performance of the boards themselves but also directly threaten the safety and reliability of building structures.

[0004] In addition, existing magnesium oxide boards have significant shortcomings in load-bearing capacity, making them unsuitable for the diverse load-bearing requirements of modern buildings. On the one hand, their local impact resistance is weak, and they are prone to damage and collapse under concentrated loads due to localized stress concentration. On the other hand, their overall uniform load-bearing effect is poor, and they are difficult to effectively distribute forces when subjected to uniformly distributed loads, which can easily lead to uneven stress distribution and low load-bearing capacity.

[0005] Based on this, the present invention designs a magnesium oxide board based on bamboo fiber filling and its preparation process to solve the above problems. Summary of the Invention

[0006] To address the aforementioned shortcomings of existing technologies, this invention provides a process for preparing magnesium oxide boards based on bamboo fiber filling, comprising the following steps:

[0007] S1: Cut and crush raw bamboo and sieve it to obtain coarse bamboo fibers. Immerse the coarse bamboo fibers completely in sodium hydroxide solution, sonicate them, take them out, rinse and dry them, spray them with silane coupling agent solution, stir and let them stand to obtain modified bamboo fibers.

[0008] S2: Take diatomaceous earth, dry it at 100-120℃ for 1.5-2.5h, add it to a ball mill and mix it with titanate coupling agent to obtain modified diatomaceous earth;

[0009] Corn starch was added to a reaction vessel, glacial acetic acid was added, the temperature was raised to 45-55℃, acetic anhydride was added dropwise and stirred, and after stirring was completed, it was washed with deionized water to obtain acetylated modified starch.

[0010] S3: Weigh 100-108 parts by weight of magnesium oxide powder, 40-60 parts by weight of magnesium sulfate solution, 30-50 parts by weight of deionized water, 80-120 parts by weight of modified bamboo fiber, 3-7 parts by weight of modified diatomaceous earth, and 2-5 parts by weight of acetylated modified starch. Add the modified diatomaceous earth and magnesium sulfate solution to a dispersion tank and stir. Then add the acetylated modified starch and continue stirring to obtain a premixed slurry.

[0011] S4: Add magnesium oxide powder to the premixed slurry in 2-3 batches while stirring to obtain magnesium oxide cement slurry. Add modified bamboo fibers to the magnesium oxide cement slurry in 3-5 batches. After all the bamboo fibers are added, transfer them to a high-speed disperser for stirring to obtain bamboo fiber magnesium oxide cement composite slurry.

[0012] S5: The bamboo fiber sulfur-oxygen magnesium cement composite slurry is delivered to the molding mold, and the mold is closed and hot-pressed; after hot pressing, the molding mold is opened and the slab is taken out. After cooling, 15-20 slabs of the same specifications are stacked and the mold is locked.

[0013] S6: Curing, drying, cutting, and polishing to obtain magnesium oxide boards based on bamboo fiber filling.

[0014] Furthermore, S1 specifically involves: selecting 3-5 year old moso bamboo, cutting it into 50-70cm long bamboo segments, processing it into thin bamboo strips 2-4cm long and 0.3-0.5mm thick using a planer, crushing it in a coarse crusher, screening it through a double-layer screen, retaining coarse bamboo fibers with a particle size of 0.3-2.5mm, completely immersing the coarse bamboo fibers in a 3-5% sodium hydroxide solution, ultrasonically treating it at 50-60℃ for 20-30 minutes, rinsing it with deionized water until the pH value reaches 7-8, and then drying it in a dryer at 45-55℃ for 1-2 hours. A silane coupling agent solution accounting for 0.4-0.9% of the bamboo fibers' mass is sprayed on the bamboo fibers, stirred for 10-15 minutes, and then allowed to stand for 20-30 minutes to obtain modified bamboo fibers.

[0015] Furthermore, S2 specifically involves: taking diatomaceous earth, drying it at 100-120℃ for 1.5-2.5 hours, adding it to a ball mill and mixing it with a titanate coupling agent accounting for 0.3-0.8% of the diatomaceous earth mass, and ball milling it at 300-400 r / min for 20-30 minutes to obtain modified diatomaceous earth;

[0016] Add corn starch to a reaction vessel, add 20-30% glacial acetic acid by weight of starch, heat to 45-55℃ at 2-4℃ / min, then add 10-15% acetic anhydride by weight of starch dropwise at 0.8-1.5mL / min, stir for 40-60min, and wash with deionized water until neutral to obtain acetylated modified starch.

[0017] Furthermore, S3 specifically involves weighing 100-108 parts by weight of magnesium oxide powder, 40-60 parts by weight of magnesium sulfate solution with a mass concentration of 22-28%, 30-50 parts by weight of deionized water, 80-120 parts by weight of modified bamboo fiber, 3-7 parts by weight of modified diatomaceous earth, and 2-5 parts by weight of acetylated modified starch. The modified diatomaceous earth and magnesium sulfate solution are added to a dispersion vessel and stirred at 600-800 r / min for 8-12 min. Then, the acetylated modified starch is added and stirring is continued for 5-8 min to obtain a premixed slurry.

[0018] Furthermore, S4 specifically involves adding magnesium oxide powder to the premixed slurry in 2-3 portions while stirring, increasing the speed to 1000-1300 r / min, and stirring for 10-15 minutes to obtain magnesium oxide cement-based slurry. Modified bamboo fibers are then added to the magnesium oxide cement-based slurry in 3-5 portions, stirring for 3-5 minutes after each addition. After all the additions are complete, the mixture is transferred to a high-speed disperser and stirred at 1500-1800 r / min for 15-20 minutes to obtain bamboo fiber magnesium oxide cement composite slurry.

[0019] Furthermore, S5 specifically involves: The bamboo fiber magnesium sulfate cement composite slurry is pumped to the molding mold via a delivery pump; the hydraulic mold closing machine is activated, and the mold is closed at a closing pressure of 0.8-1.2 MPa. During the mold closing process, the overflow chute on the side of the mold is opened to discharge excess slurry. After the mold cavity is completely filled, the mold closing pressure is maintained for 30-40 seconds to complete the initial fixing. The mold is then transferred to a hot press, employing a three-stage hot pressing process. The first stage involves hot pressing at 0.4-0.6 MPa and 50-60℃ for 15-20 seconds; the second stage involves hot pressing at 1.2-1.6 MPa and 60-70℃ for 30-... 45s; The third stage involves heating to 70-80℃ and reducing the pressure to 0.3-0.5MPa, followed by hot pressing for 25-35s; After hot pressing, the shaping mold is opened to remove the slab, which is then allowed to cool naturally to 35-45℃. 15-20 slabs of the same specifications are selected, aligned and stacked using the mold positioning pins as a reference. A 0.1-0.2mm thick high-temperature resistant silicone pad is placed between each slab. The stacked slab group is then placed into the transfer mold-locking frame, and the mechanical mold-locking mechanism is activated. A mold-locking pressure of 0.2-0.3MPa is applied from the perimeter to the center to ensure that the slab group does not loosen or shift, thus completing the mold-locking process.

[0020] Furthermore, S6 specifically involves: sending the molded material into a curing chamber; in the first stage, controlling the temperature at 45-55℃ and the relative humidity at 65-75%, curing for 2-3 hours; in the second stage, cooling down to 35-45℃ at 1-2℃ / min and maintaining a relative humidity of 50-60%, curing for 1-2 hours, then unlocking and demolding; placing the demolded board into a constant temperature curing room, curing at 30-40℃ and a relative humidity of 40-50% for 5-8 days, ventilating 1-2 times daily during this period; after curing, drying the board at 40-55℃ for 1-2 hours, and then cutting and grinding the edges to obtain a magnesium oxide board based on bamboo fiber filling.

[0021] A magnesium oxide board based on bamboo fiber filling, prepared according to the aforementioned preparation process.

[0022] Compared with the prior art, the beneficial effects of this invention are as follows:

[0023] 1. This invention optimizes the internal filling structure through the synergistic use of bamboo fibers, modified starch, and modified diatomaceous earth, significantly reducing the risk of deformation during use. Even under long-term external forces, it maintains structural stability, avoiding localized loosening or overall deformation caused by poor material bonding. The segmented hot-pressing process ensures uniform material density within the board, enhancing local impact resistance to withstand instantaneous forces from concentrated loads, while also improving overall uniform load-bearing capacity. It can stably withstand uniformly distributed loads, meeting load-bearing requirements whether used as floor decking for prefabricated housing or to support interior decoration or equipment, making it suitable for various building scenarios.

[0024] 2. This invention, while ensuring mechanical properties, uses modified bamboo fiber as the main filler material to effectively control the surface density of the board, avoiding the problem of excessive building weight caused by the need to increase the thickness of traditional cement pressure boards to meet strength requirements. The lightweight characteristics not only reduce the overall structural load of the building but also facilitate transportation and installation in prefabricated construction, meeting the core requirements of efficient construction of prefabricated houses. Simultaneously, it reduces the amount of building materials used, achieving cost reduction and environmental protection to a certain extent.

[0025] 3. The bamboo fibers of this invention are treated with alkali to remove impurities and improve surface properties, reducing the risk of mold or insect infestation in the later stages and extending the service life of the material; the acetylated modified starch has stronger water resistance and stability than unmodified starch, avoiding the impact of starch degradation on the overall structural strength of the board; combined with multi-stage curing and constant temperature curing process, it further promotes full internal reaction of the material, reduces quality problems such as cracking and delamination in the later stages, and ensures the durability and reliability of the board in long-term use. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0027] Example 1: This example discloses a preparation process for magnesium oxide boards based on bamboo fiber filling, including the following steps:

[0028] S1: Select 3-5 year old moso bamboo, cut it into 50-70cm long bamboo sections, process it into thin bamboo strips 2-4cm long and 0.3-0.5mm thick using a planer, feed it into a coarse crusher for crushing, and then screen it through a double-layer screen (upper layer with a 2.5mm aperture and lower layer with a 0.3mm aperture) to retain coarse bamboo fibers with a particle size of 0.3-2.5mm. Immerse the coarse bamboo fibers completely in a 3% sodium hydroxide solution and ultrasonically treat them at 50℃ for 20min. Remove them and rinse them with deionized water until the pH value reaches 7-8. Dry them in a dryer at 45℃ for 1h. Spray them with a 0.4% silane coupling agent solution (KH550, diluted with a 2% ethanol solution, with a coupling agent to ethanol volume ratio of 1:5) by weight of the bamboo fibers, stir for 10min, and let them stand for 20min to obtain modified bamboo fibers.

[0029] S2: Take diatomaceous earth (particle size 200-300 mesh), dry it at 100℃ for 1.5h, add it to a ball mill and mix it with 0.3% of titanate coupling agent (NXH-101) by mass of diatomaceous earth at 300r / min for 20min (ball-to-material ratio 3:1) to obtain modified diatomaceous earth;

[0030] Corn starch was added to a reaction vessel, along with glacial acetic acid accounting for 20% of the starch mass. The temperature was increased to 45°C at 2°C / min, and then acetic anhydride accounting for 10% of the starch mass was added dropwise at 0.8 mL / min. The mixture was stirred for 40 min, and after stirring, it was washed with deionized water until neutral to obtain acetylated modified starch.

[0031] S3: Weigh out 100 parts by weight of magnesium oxide powder, 40 parts by weight of magnesium sulfate solution (mass concentration 22%), 30 parts by weight of deionized water, 80 parts by weight of modified bamboo fiber, 3 parts by weight of modified diatomaceous earth, and 2 parts by weight of acetylated modified starch. Add the modified diatomaceous earth and magnesium sulfate solution to the dispersion vessel and stir at 600 r / min for 8 min. Then add the acetylated modified starch and continue stirring for 5 min to obtain the premixed slurry.

[0032] S4: Add magnesium oxide powder to the premixed slurry in two batches while stirring. Increase the speed to 1000 r / min and stir for 10 min to obtain magnesium oxide cement-based slurry. Add modified bamboo fibers to the magnesium oxide cement-based slurry in three batches, stirring for 3 min after each addition. After all the fibers are added, transfer them to a high-speed disperser and stir at 1500 r / min for 15 min to obtain bamboo fiber magnesium oxide cement composite slurry.

[0033] S5: The bamboo fiber magnesium sulfate cement composite slurry is delivered to the molding mold via a delivery pump. The hydraulic mold closing machine is started, and the mold is closed with a closing pressure of 0.8MPa. During the mold closing process, the overflow groove on the side of the mold is opened to discharge excess slurry. After the mold cavity is completely filled, the mold closing pressure is maintained for 30 seconds to complete the initial fixing. Then, it is transferred to the hot press and a three-stage hot pressing is adopted. The first stage is hot pressing at 0.4MPa and 50℃ for 15 seconds; the second stage is hot pressing at 1.2MPa and 60℃ for 30 seconds; the third stage is heated... The temperature is raised to 70℃, the pressure is reduced to 0.3MPa, and hot pressing is performed for 25 seconds. After hot pressing, the shaping mold is opened and the slab is removed. It is allowed to cool naturally to 35℃. 15 slabs of the same specifications are selected, aligned and stacked with the mold positioning pin as the reference. A 0.1mm thick high-temperature resistant silicone pad is laid between each slab (to prevent sticking). The stacked slab group is placed into the transfer mold locking frame, and the mechanical mold locking mechanism is activated. A mold locking pressure of 0.2MPa is applied from the periphery to the center to ensure that the slab group does not loosen or shift, and the mold locking is completed.

[0034] S6: The molded material is sent into the curing chamber. In the first stage, the temperature is controlled at 45℃ and the relative humidity at 65%, and the curing time is 2 hours. In the second stage, the temperature is reduced to 35℃ and the relative humidity is 50% at a rate of 1℃ / min. After curing for 1 hour, the mold is unlocked and the board is demolded. The demolded board is placed in a constant temperature curing room and cured at 30℃ and 40% relative humidity for 5 days. During this period, the board is ventilated once a day. After curing, the board is dried at 40℃ for 1 hour. After cutting and edge grinding, an 8mm thick magnesium oxide board based on bamboo fiber filling is obtained.

[0035] Example 2: This example discloses a preparation process for magnesium oxide boards based on bamboo fiber filling, including the following steps:

[0036] S1: Select 3-5 year old moso bamboo, cut it into 50-70cm long bamboo sections, process it into thin bamboo strips 2-4cm long and 0.3-0.5mm thick using a planer, feed it into a coarse crusher for crushing, and then screen it through a double-layer screen (upper layer with a 2.5mm aperture and lower layer with a 0.3mm aperture) to retain coarse bamboo fibers with a particle size of 0.3-2.5mm. Immerse the coarse bamboo fibers completely in a 5% sodium hydroxide solution and ultrasonically treat them at 60℃ for 30min. Remove them and rinse them with deionized water until the pH value reaches 7-8. Dry them in a dryer at 55℃ for 2h. Spray them with a 0.9% silane coupling agent solution (KH560, diluted with a 4% ethanol solution, with a coupling agent to ethanol volume ratio of 1:5) by the weight of the bamboo fibers, stir for 15min and let them stand for 30min to obtain modified bamboo fibers.

[0037] S2: Take diatomaceous earth (particle size 200-300 mesh), dry it at 120℃ for 2.5h, add it to a ball mill and mix it with titanate coupling agent (NXH-101) accounting for 0.8% of the mass of diatomaceous earth at 400r / min for 30min (ball-to-material ratio 3:1) to obtain modified diatomaceous earth;

[0038] Corn starch was added to a reaction vessel, along with glacial acetic acid accounting for 30% of the starch mass. The temperature was increased to 55°C at 4°C / min, and then acetic anhydride accounting for 15% of the starch mass was added dropwise at 1.5 mL / min. The mixture was stirred for 60 min, and after stirring, it was washed with deionized water until neutral to obtain acetylated modified starch.

[0039] S3: Weigh out 108 parts by weight of magnesium oxide powder, 60 parts by weight of magnesium sulfate solution (mass concentration 28%), 50 parts by weight of deionized water, 120 parts by weight of modified bamboo fiber, 7 parts by weight of modified diatomaceous earth, and 5 parts by weight of acetylated modified starch. Add the modified diatomaceous earth and magnesium sulfate solution to the dispersion vessel and stir at 800 r / min for 12 min. Then add the acetylated modified starch and continue stirring for 8 min to obtain the premixed slurry.

[0040] S4: Add magnesium oxide powder to the premixed slurry in 3 batches while stirring. Increase the speed to 1300 r / min and stir for 15 min to obtain magnesium oxide cement-based slurry. Add modified bamboo fibers to the magnesium oxide cement-based slurry in 5 batches, stirring for 5 min after each addition. After all the addition is complete, transfer to a high-speed disperser and stir at 1800 r / min for 20 min to obtain bamboo fiber magnesium oxide cement composite slurry.

[0041] S5: The bamboo fiber magnesium sulfate cement composite slurry is delivered to the molding mold via a delivery pump. The hydraulic mold closing machine is started, and the mold is closed with a closing pressure of 1.2 MPa. During the mold closing process, the overflow groove on the side of the mold is opened to discharge excess slurry. After the mold cavity is completely filled, the mold closing pressure is maintained for 40 seconds to complete the initial fixing. Then, it is transferred to the hot press and a three-stage hot pressing is adopted. The first stage is hot pressing at 0.6 MPa and 60℃ for 20 seconds; the second stage is hot pressing at 1.6 MPa and 70℃ for 45 seconds; the third stage is heated... The temperature is raised to 80℃, the pressure is reduced to 0.5MPa, and hot pressing is performed for 35 seconds. After hot pressing, the shaping mold is opened and the slab is removed. It is allowed to cool naturally to 45℃. Twenty slabs of the same specifications are selected, aligned and stacked with the mold positioning pin as the reference. A 0.2mm thick high-temperature resistant silicone pad is laid between each slab (to prevent sticking). The stacked slab group is placed into the transfer mold locking frame, and the mechanical mold locking mechanism is activated. A mold locking pressure of 0.3MPa is applied from the periphery to the center to ensure that the slab group does not loosen or shift, and the mold locking is completed.

[0042] S6: The molded material is sent into the curing chamber. In the first stage, the temperature is controlled at 55℃ and the relative humidity at 75%, and the curing time is 3 hours. In the second stage, the temperature is reduced to 45℃ and the relative humidity is 60% at a rate of 2℃ / min. After curing for 2 hours, the mold is unlocked and the board is demolded. The demolded board is placed in a constant temperature curing room and cured at 40℃ and 50% relative humidity for 8 days. During this period, the board is ventilated twice a day. After curing, the board is dried at 55℃ for 2 hours. After cutting and edge grinding, a 15mm thick magnesium oxide board based on bamboo fiber filling is obtained.

[0043] Example 3: This example discloses a preparation process for magnesium oxide boards based on bamboo fiber filling, including the following steps:

[0044] S1: Select 3-5 year old moso bamboo, cut it into 50-70cm long bamboo sections, process it into thin bamboo strips 2-4cm long and 0.3-0.5mm thick using a planer, feed it into a coarse crusher for crushing, and then screen it through a double-layer screen (upper layer with a 2.5mm aperture and lower layer with a 0.3mm aperture) to retain coarse bamboo fibers with a particle size of 0.3-2.5mm. Immerse the coarse bamboo fibers completely in a 4% sodium hydroxide solution and ultrasonically treat them at 56℃ for 26min. Remove them and rinse them with deionized water until the pH value reaches 7-8. Dry them in a dryer at 51℃ for 2h. Spray them with a 0.7% silane coupling agent solution (KH570, diluted with a 3% ethanol solution, with a coupling agent to ethanol volume ratio of 1:5) by the weight of the bamboo fibers. Stir for 13min and let stand for 24min to obtain modified bamboo fibers.

[0045] S2: Take diatomaceous earth (particle size 200-300 mesh), dry it at 114℃ for 2 hours, add it to a ball mill and mix it with 0.6% of titanate coupling agent (NXH-101) by mass of diatomaceous earth at 340 r / min for 27 min (ball-to-material ratio 3:1) to obtain modified diatomaceous earth;

[0046] Corn starch was added to a reaction vessel, along with glacial acetic acid accounting for 24% of the starch mass. The temperature was increased to 52°C at 3°C / min, and then acetic anhydride accounting for 12% of the starch mass was added dropwise at 1.1 mL / min. The mixture was stirred for 55 min, and after stirring, it was washed with deionized water until neutral to obtain acetylated modified starch.

[0047] S3: Weigh out 105 parts by weight of magnesium oxide powder, 48 parts by weight of magnesium sulfate solution (mass concentration 26%), 46 parts by weight of deionized water, 97 parts by weight of modified bamboo fiber, 6 parts by weight of modified diatomaceous earth, and 3 parts by weight of acetylated modified starch. Add the modified diatomaceous earth and magnesium sulfate solution to the dispersion vessel and stir at 720 r / min for 11 min. Then add the acetylated modified starch and continue stirring for 6 min to obtain the premixed slurry.

[0048] S4: Add magnesium oxide powder to the premixed slurry in 3 batches while stirring. Increase the speed to 1200 r / min and stir for 12 min to obtain magnesium oxide cement-based slurry. Add modified bamboo fibers to the magnesium oxide cement-based slurry in 5 batches, stirring for 3 min after each addition. After all the fibers are added, transfer them to a high-speed disperser and stir at 1750 r / min for 18 min to obtain bamboo fiber magnesium oxide cement composite slurry.

[0049] S5: The bamboo fiber magnesium sulfate cement composite slurry is delivered to the molding mold via a delivery pump. The hydraulic mold closing machine is started, and the mold is closed with a closing pressure of 1 MPa. During the mold closing process, the overflow chute on the side of the mold is opened to discharge excess slurry. After the mold cavity is completely filled, the mold closing pressure is maintained for 38 seconds to complete the initial fixing. Then, it is transferred to the hot press, using a three-stage hot pressing process. The first stage is hot pressing at 0.6 MPa and 56℃ for 17 seconds; the second stage is hot pressing at 1.4 MPa and 66℃ for 40 seconds; the third stage is heated to... At 74℃, the pressure is reduced to 0.4MPa, and hot pressing is performed for 30 seconds. After hot pressing, the shaping mold is opened and the slab is removed. It is then allowed to cool naturally to 38℃. Seventeen slabs of the same specifications are selected, aligned and stacked with the mold positioning pins as the reference. A 0.2mm thick high-temperature resistant silicone pad is placed between each slab (to prevent sticking). The stacked slab group is placed into the transfer mold-locking frame, and the mechanical mold-locking mechanism is activated. A mold-locking pressure of 0.3MPa is applied from the periphery to the center to ensure that the slab group does not loosen or shift, thus completing the mold-locking process.

[0050] S6: The molded material is sent into the curing chamber. In the first stage, the temperature is controlled at 51℃ and the relative humidity at 70%, and the curing time is 3 hours. In the second stage, the temperature is reduced to 42℃ and the relative humidity is controlled at 55% at a rate of 2℃ / min. After curing for 2 hours, the mold is unlocked and the board is demolded. The demolded board is placed in a constant temperature curing room and cured at 32℃ and 44% relative humidity for 6 days. During this period, the board is ventilated twice a day. After curing, the board is dried at 48℃ for 2 hours. After cutting and edge grinding, a 10mm thick magnesium oxide board based on bamboo fiber filling is obtained.

[0051] Comparative Example 1: The difference between this comparative example and Example 3 is that in S1, the bamboo fibers were not modified and coarse bamboo fibers were directly selected.

[0052] Comparative Example 2: The difference between this comparative example and Example 3 is that, in S2, the corn starch was not modified.

[0053] Comparative Example 3: The difference between this comparative example and Example 3 is that in S5, segmented hot pressing was not performed, and the hot pressing was directly performed at 1.4 MPa and 66°C for 87 seconds.

[0054] Experimental example: The areal density of the magnesium oxide board based on bamboo fiber filling prepared according to GB / T 30100-2013 was tested. ), deflection (mm), maximum concentrated failure load Pmax (N) and maximum uniformly distributed failure load Pmax+Wp (N) at a loading rate of 20N / s.

[0055] The test results are shown in the table below:

[0056]

[0057] As shown in the table above, the deflection of the board made of unmodified bamboo fibers increased significantly, indicating a decrease in resistance to deformation; the maximum concentrated failure load and the maximum uniformly distributed failure load both decreased, indicating a deterioration in load-bearing capacity.

[0058] The boards made from unmodified starch have a slightly higher deflection than those made from modified starch, and their resistance to deformation is slightly weaker.

[0059] Segmented hot pressing has a more significant effect on optimizing the maximum concentrated destructive load. Without it, the local impact resistance is damaged, and it will also affect the overall uniform load-bearing capacity. However, its impact on the overall structural stability is weaker than its impact on local performance.

[0060] The increase in thickness has a significant effect on the maximum concentrated failure load, and the local impact resistance of thick plates is far superior to that of thin plates. The effect of thickness on the maximum uniformly distributed failure load is relatively small, indicating that the overall uniform load-bearing capacity depends not only on the thickness, but also on factors such as the uniformity of the internal structure of the material and the bond strength.

[0061] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation process for magnesium oxide boards based on bamboo fiber filling, characterized in that, Includes the following steps: S1: Cut and crush raw bamboo and sieve it to obtain coarse bamboo fibers. Immerse the coarse bamboo fibers completely in sodium hydroxide solution, sonicate them, take them out, rinse and dry them, spray them with silane coupling agent solution, stir and let them stand to obtain modified bamboo fibers. S2: Take diatomaceous earth, dry it at 100-120℃ for 1.5-2.5h, add it to a ball mill and mix it with titanate coupling agent to obtain modified diatomaceous earth; Corn starch was added to a reaction vessel, glacial acetic acid was added, the temperature was raised to 45-55℃, acetic anhydride was added dropwise and stirred, and after stirring was completed, it was washed with deionized water to obtain acetylated modified starch. S3: Weigh 100-108 parts by weight of magnesium oxide powder, 40-60 parts by weight of magnesium sulfate solution, 30-50 parts by weight of deionized water, 80-120 parts by weight of modified bamboo fiber, 3-7 parts by weight of modified diatomaceous earth, and 2-5 parts by weight of acetylated modified starch. Add the modified diatomaceous earth and magnesium sulfate solution to a dispersion tank and stir. Then add the acetylated modified starch and continue stirring to obtain a premixed slurry. S4: Add magnesium oxide powder to the premixed slurry in 2-3 batches while stirring to obtain magnesium oxide cement slurry. Add modified bamboo fibers to the magnesium oxide cement slurry in 3-5 batches. After all the bamboo fibers are added, transfer them to a high-speed disperser for stirring to obtain bamboo fiber magnesium oxide cement composite slurry. S5: The bamboo fiber sulfur-oxygen magnesium cement composite slurry is delivered to the molding mold, and the mold is closed and hot-pressed; after hot pressing, the molding mold is opened and the slab is taken out. After cooling, 15-20 slabs of the same specifications are stacked and the mold is locked. S6: Curing, drying, cutting, and polishing to obtain magnesium oxide boards based on bamboo fiber filling.

2. The preparation process of magnesium oxide board based on bamboo fiber filling according to claim 1, characterized in that, S1 specifically involves: selecting 3-5 year old moso bamboo, cutting it into 50-70cm long bamboo segments, processing it into thin bamboo strips 2-4cm long and 0.3-0.5mm thick using a planer, crushing it in a coarse crusher, screening it through a double-layer screen, retaining coarse bamboo fibers with a particle size of 0.3-2.5mm, completely immersing the coarse bamboo fibers in a 3-5% sodium hydroxide solution, ultrasonically treating it at 50-60℃ for 20-30 minutes, rinsing it with deionized water until the pH value reaches 7-8, and then drying it in a dryer at 45-55℃ for 1-2 hours. A silane coupling agent solution accounting for 0.4-0.9% of the bamboo fibers' mass is sprayed on, stirred for 10-15 minutes, and then allowed to stand for 20-30 minutes to obtain modified bamboo fibers.

3. The preparation process of magnesium oxide board based on bamboo fiber filling according to claim 1, characterized in that, S2 is specifically as follows: take diatomaceous earth, dry it at 100-120℃ for 1.5-2.5h, add it to a ball mill and mix it with 0.3-0.8% of titanate coupling agent by mass of diatomaceous earth at 300-400r / min for 20-30min to obtain modified diatomaceous earth; Add corn starch to a reaction vessel, add 20-30% glacial acetic acid by weight of starch, heat to 45-55℃ at 2-4℃ / min, then add 10-15% acetic anhydride by weight of starch dropwise at 0.8-1.5mL / min, stir for 40-60min, and wash with deionized water until neutral to obtain acetylated modified starch.

4. The preparation process of magnesium oxide board based on bamboo fiber filling according to claim 1, characterized in that, S3 is specifically as follows: Weigh 100-108 parts by weight of magnesium oxide powder, 40-60 parts by weight of magnesium sulfate solution with a mass concentration of 22-28%, 30-50 parts by weight of deionized water, 80-120 parts by weight of modified bamboo fiber, 3-7 parts by weight of modified diatomaceous earth, and 2-5 parts by weight of acetylated modified starch. Add the modified diatomaceous earth and magnesium sulfate solution to a dispersion vessel and stir at 600-800 r / min for 8-12 min. Then add the acetylated modified starch and continue stirring for 5-8 min to obtain the premixed slurry.

5. The preparation process of magnesium oxide board based on bamboo fiber filling according to claim 1, characterized in that, S4 specifically involves adding magnesium oxide powder to the premixed slurry in 2-3 batches while stirring, increasing the speed to 1000-1300 r / min, and stirring for 10-15 min to obtain magnesium oxide cement-based slurry. Modified bamboo fibers are then added to the magnesium oxide cement-based slurry in 3-5 batches, stirring for 3-5 min after each addition. After all the additions are complete, the mixture is transferred to a high-speed disperser and stirred at 1500-1800 r / min for 15-20 min to obtain bamboo fiber magnesium oxide cement composite slurry.

6. The preparation process of magnesium oxide board based on bamboo fiber filling according to claim 1, characterized in that, S5 specifically involves: conveying the bamboo fiber sulfur-oxygen magnesium cement composite slurry to the molding mold via a delivery pump, starting the hydraulic mold closing machine, closing the mold with a mold closing pressure of 0.8-1.2MPa, opening the overflow groove on the side of the mold during the mold closing process to discharge excess slurry, and maintaining the mold closing pressure for 30-40s to complete the initial fixing after the mold cavity is completely filled, then transferring to the hot press, using a three-stage hot pressing method, with the first stage being hot pressing at 0.4-0.6MPa and 50-60℃ for 15-20s; The second stage involves hot pressing at 1.2-1.6 MPa and 60-70℃ for 30-45 seconds; the third stage involves raising the temperature to 70-80℃, reducing the pressure to 0.3-0.5 MPa, and hot pressing for 25-35 seconds; after hot pressing, the shaping mold is opened to remove the slab, which is then allowed to cool naturally to 35-45℃. 15-20 slabs of the same specifications are selected, aligned and stacked using the mold positioning pins as a reference. A 0.1-0.2 mm thick high-temperature resistant silicone pad is placed between each slab. The stacked slab group is then placed into the transfer mold-locking frame, and the mechanical mold-locking mechanism is activated to apply a mold-locking pressure of 0.2-0.3 MPa from all sides to the center to ensure that the slab group does not loosen or shift, thus completing the mold-locking process.

7. The preparation process of magnesium oxide board based on bamboo fiber filling according to claim 1, characterized in that, S6 specifically involves: sending the molded material into a curing chamber; in the first stage, controlling the temperature at 45-55℃ and the relative humidity at 65-75%, curing for 2-3 hours; in the second stage, cooling down to 35-45℃ at 1-2℃ / min and maintaining a relative humidity of 50-60%, curing for 1-2 hours, then unlocking and demolding; placing the demolded board into a constant temperature curing room and curing at 30-40℃ and 40-50% relative humidity for 5-8 days, ventilating 1-2 times a day during this period; after curing, drying the board at 40-55℃ for 1-2 hours, and then cutting and grinding the edges to obtain a magnesium oxide board based on bamboo fiber filling.

8. A magnesium oxide board based on bamboo fiber filling, prepared by the preparation process according to any one of claims 1-7.

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