Hollow fireproof gypsum door core and its preparation method

Abstract

The application discloses a hollow fireproof gypsum door core board and a preparation method thereof, and relates to the technical field of building fireproof materials. The modified cementing material is prepared by mixing and calcining phosphogypsum as an industrial by-product and desulfurization gypsum, and then modifying the phosphogypsum and the desulfurization gypsum by using an aluminic ester coupling agent and redispersible latex powder; the modified reinforcing material is prepared by pretreating short-cut glass fibers and rock wool fibers, and then modifying surfaces of the short-cut glass fibers and the rock wool fibers by using a silane coupling agent; then, the above materials, light filling materials, a foaming agent, a water reducing agent and other components are mixed in proportion to prepare a pulp, and the pulp is poured into a mold to finally obtain the hollow fireproof gypsum door core board. The application not only realizes high-value utilization of the industrial by-product gypsum, but also has excellent folding strength and fireproof performance, is light in weight, and is suitable for industrial large-scale production, and can be widely applied to the manufacturing of various fireproof doors.

Description

Technical Field

[0001] This application relates to the field of fireproof building materials technology, and in particular to a hollow fireproof gypsum board and its preparation method. Background Technology

[0002] With increasingly stringent fire safety requirements for buildings, fire doors, as key components of building fire protection systems, have received widespread attention for their fire resistance, mechanical properties, and durability. The core panel is the core component determining the overall performance of a fire door. Currently, commonly used fire door core panels on the market include aluminum silicate wool board, rock wool board, perlite board, and gypsum board. Among these, gypsum board has been widely used in the fire door industry due to its excellent fire and heat insulation properties, wide availability of raw materials, and low price.

[0003] However, traditional solid gypsum board has many insurmountable drawbacks. First, the high density of solid gypsum board results in excessively heavy fire doors, increasing transportation and installation costs and causing premature damage to hinges, door frames, and other hardware, thus shortening the lifespan of the fire doors. Second, pure gypsum material is brittle, with poor flexural strength and impact resistance, making it prone to cracking and breakage during production, transportation, and use. Finally, traditional solid gypsum board primarily uses natural gypsum as raw material, consuming significant amounts of natural resources, while large quantities of industrial byproducts such as phosphogypsum and desulfurized gypsum are not effectively recycled, resulting in resource waste.

[0004] Therefore, developing a lightweight, high-strength, fire-resistant, and heat-insulating hollow fireproof gypsum door core board and its preparation method that can consume large quantities of industrial by-product gypsum is of significant economic value and importance. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this application provides a hollow fireproof gypsum door core board and its preparation method. Phosphogypsum, an industrial byproduct, is mixed with desulfurized gypsum and calcined. The mixture is then modified with an aluminate coupling agent and redispersible latex powder to prepare a modified cementitious material. Short-cut glass fibers and rock wool fibers are pretreated and then surface-modified with a silane coupling agent to prepare a modified reinforcing material. The above materials, along with lightweight fillers, foaming agents, and water-reducing agents, are then mixed in a specific ratio to form a slurry, which is then poured into a mold to finally obtain a hollow fireproof gypsum door core board. This application not only achieves high-value utilization of industrial byproduct gypsum, but the resulting door core board also possesses excellent flexural strength and fire resistance, while being lightweight.

[0006] To achieve the above objectives, this application adopts the following technical solution:

[0007] In a first aspect, this application provides a hollow fireproof gypsum core board, the raw materials of which include: modified cementitious material, modified reinforcing material, lightweight filler material, foaming agent, water-reducing agent, retarder, moisture-proofing agent and water; the modified cementitious material is prepared by mixing and calcining phosphogypsum and desulfurized gypsum and grinding them into a mixed powder, and then adding an aluminate coupling agent and redispersible latex powder to it; the modified reinforcing material is obtained by pretreating and mixing short-cut glass fiber and rock wool fiber, and then adding a silane coupling agent dispersion for surface modification.

[0008] In one feasible implementation, the aluminate coupling agent is isopropyl distearate aluminate.

[0009] When phosphogypsum, the main component of modified cementitious materials, is mixed and calcined with desulfurized gypsum, the alkaline impurities in the desulfurized gypsum can neutralize the soluble phosphorus, fluorine, and other harmful impurities in the phosphogypsum, eliminating their retardation effect on gypsum hardening. The product after calcining the mixed phosphogypsum and desulfurized gypsum is ground into a mixed powder, and an aluminate coupling agent is added. Through a chemical reaction, the aluminate coupling agent introduces long-chain alkyl organic groups onto the surface of the mixed powder, significantly improving its compatibility with redispersible latex powder. During the hydration process of the gypsum mixed powder, the redispersible latex powder disperses into polymer particles, forming a continuous, flexible polymer film between the gypsum mixed powder particles. This film fills the pores and binds the gypsum mixed powder, improving both the toughness and adhesion of the matrix while blocking water penetration channels.

[0010] In the modified reinforcing materials, chopped glass fibers provide high tensile strength and elastic modulus, while rock wool fibers offer excellent fire resistance, heat insulation, and impact toughness. The optimal ratio of these two fibers compensates for the shortcomings of a single fiber. Furthermore, the silanoxy group at one end of the silane coupling agent molecule hydrolyzes to generate silanol groups, which condense with the hydroxyl groups on the surface of the mixed fibers to form covalent bonds. The organic groups at the other end can form hydrogen bonds or other chemical bonds with the resulting modified cementitious material, thereby enhancing the interfacial bonding between the modified reinforcing material and the modified cementitious material. This allows the two main raw materials in the fireproof gypsum core board provided in this application to mix and bond better, thus enhancing the performance of the resulting fireproof gypsum core board.

[0011] In addition, the fireproof gypsum core board provided in this application has a hollow structure with through holes inside, which can effectively reduce the amount of material used without significantly reducing its overall mechanical properties, and finally obtain a gypsum core board that is lightweight, high-strength, and has excellent fireproof and heat insulation performance.

[0012] In one feasible implementation, the mass ratio of the modified cementitious material, modified reinforcing material, lightweight filler, foaming agent, water-reducing agent, retarder, and moisture-proofing agent is (60-80):(5-15):(10-25):(0.1-0.5):(0.2-1):(0.1-0.5):(0.5-2); and the mass of water in the raw materials is 30-50% of the total mass of the other raw materials.

[0013] In this application, the modified cementitious material is used as the matrix material of the gypsum door core board. Its proportion is controlled at 60-80% to ensure the basic flexural strength and fire resistance of the gypsum door core board. If it is less than 60%, the strength will be insufficient, and if it is more than 80%, the density will be too high.

[0014] The fibers in the modified reinforcing material can form a uniform three-dimensional network structure in the gypsum board, achieving the best reinforcing effect. If the fiber content is below 5%, the reinforcing effect is not obvious; if it is above 15%, the excessive amount of fibers is prone to agglomeration, which can easily lead to stress concentration and reduce the strength of the gypsum board.

[0015] The use of lightweight filler materials can effectively reduce the density of gypsum board, but if the amount exceeds 25%, it will destroy the continuity of the matrix of the gypsum board, resulting in a significant decrease in strength.

[0016] Functional additives can work even in low concentrations, but excessive use can interfere with the normal hydration process of gypsum, leading to problems such as abnormal setting time and reduced strength.

[0017] Ultimately, controlling the water-to-material ratio at 30-50% ensures that the slurry has good fluidity and casting performance, while also preventing excessive water evaporation from forming a large number of harmful pores, thus ensuring the density of the resulting gypsum door core board.

[0018] In one feasible implementation, the mass ratio of phosphogypsum, desulfurized gypsum, aluminate coupling agent, and redispersible latex powder in the modified cementitious material is (60-70):(15-30):(0.5-2):(5-10); the redispersible latex powder includes any one of ethylene-vinyl acetate copolymer, acrylate copolymer, and styrene-butadiene copolymer.

[0019] Among modified cementitious materials, the ratio of phosphogypsum to desulfurized gypsum is the optimal range after optimization. Within this range, the hydration rate of the hemihydrate gypsum after calcination of the two is moderate, and the setting time meets the construction requirements. Among the redispersible latex powders, ethylene-vinyl acetate copolymer, acrylate copolymer, and styrene-butadiene copolymer all exhibit good film-forming properties and compatibility with gypsum modified with aluminate coupling agents. Their use can effectively improve the flexural strength and impact resistance of gypsum board matrix.

[0020] In one feasible implementation, the modified reinforcing material contains a chopped glass fiber to rock wool fiber mass ratio of (20-40):(60-80); the chopped glass fiber has a length of 3-12 mm, and the rock wool fiber has a length of 5-8 mm; the silane coupling agent dispersion is used at 0.5-1.5% of the total mass of the chopped glass fiber and rock wool fiber; the silane coupling agent dispersion comprises a silane coupling agent, ethanol, and water; the silane coupling agent, ethanol, and water mass ratio is (15-20):(50-65):(20-30); the silane coupling agent comprises any one of 7-octenyltrimethoxysilane, n-octyltrimethoxysilane, and anilinemethyltrimethoxysilane.

[0021] By controlling the mass ratio and length range of chopped glass fibers to rock wool fibers, the resulting modified reinforced material achieves both mechanical and fire-resistant properties. The use of silane coupling agents introduces organic groups such as 7-octenyl, n-octyl, and aniline methyl groups onto the surface of the modified reinforced material, improving its dispersibility and interfacial bonding within the gypsum board matrix.

[0022] In one feasible implementation, the lightweight filler material includes any one or more of expanded perlite, vitrified microspheres, and fly ash; the foaming agent includes any one of sodium dodecyl sulfate, sodium fatty alcohol polyoxyethylene ether sulfate, and sodium α-alkenyl sulfonate; the water-reducing agent is a polycarboxylate water-reducing agent; the retarder includes any one of citric acid, tartaric acid, and borax; and the moisture-proofing agent includes any one of calcium stearate and zinc stearate.

[0023] In one feasible implementation, the door core panel has solid side edges at both ends in the width direction, and through holes with isosceles trapezoidal cross-sections are arranged in a single row at equal intervals along the width direction of the door core panel; the through holes extend through the length direction of the door core panel.

[0024] Preferably, the door core panel has a length of 2100mm, a width of 900mm, and a thickness of 48mm; each of the left and right ends of the door core panel in the width direction has a solid side edge of 18mm width; 15 through holes with isosceles trapezoidal cross-sections are arranged in a single row at equal intervals along the width direction of the door core panel; the height of the isosceles trapezoid is 30mm, one base is 45mm, and the other base is 47mm; the through holes extend through the length direction of the door core panel.

[0025] By controlling parameters such as the shape and diameter of the through holes in the door core panel, the weight of the resulting door core panel can be reduced, while the remaining solid material can still provide sufficient compressive and flexural strength. Furthermore, if the through hole diameter is too large, the gaps between the through holes will be too thin, resulting in insufficient overall strength of the door core panel; if the hole diameter is too small, the weight reduction effect of the door core panel will be insignificant.

[0026] Secondly, this application provides a method for preparing a hollow fireproof gypsum door core board, comprising the following steps:

[0027] S1. Phosphogypsum and desulfurized gypsum are mixed and calcined in air, cooled to room temperature, ground into a mixed powder, and then fed into a mixing device. Aluminate coupling agent is added to it, and it is stirred for a first time at a first temperature and a first speed. Then redispersible latex powder is added, and it is stirred for a second time at a second speed. Finally, it is cooled to room temperature and discharged to obtain the modified cementitious material.

[0028] S2. The chopped glass fibers and rock wool fibers are ultrasonically cleaned with ethanol, filtered, and dried separately to obtain pretreated chopped glass fibers and pretreated rock wool fibers. The pretreated chopped glass fibers and pretreated rock wool fibers are then put into a mixing device and stirred at room temperature for a third time. Then, a silane coupling agent dispersion is sprayed into the mixture through a nozzle while stirring. The mixture is stirred at the third speed and at the second temperature for a fourth time. The mixture is then cooled to room temperature and discharged to obtain the modified reinforced material.

[0029] S3. Weigh the modified cementitious material, modified reinforcing material, lightweight filler, foaming agent, water-reducing agent, retarder and moisture-proofing agent according to the proportion, put them into the mixing equipment, stir at the fourth speed for five hours at room temperature, then add water and stir at the fifth speed for six hours to obtain the mixed slurry.

[0030] S4. Pour the mixed slurry into a mold with a detachable core mold, vibrate to remove air, and after initial setting, pull out the core and after final setting, demold to obtain a hollow fireproof gypsum door core board.

[0031] In the preparation method of the hollow fireproof gypsum door core board provided in this application, the modified cementitious material and the modified reinforcing material are prepared separately first. This ensures that the coupling agent and latex powder react fully on the surface of their respective modified objects, and avoids mutual interference during the mixing process, which would affect the modification effect.

[0032] Furthermore, dry mixing all solid raw materials before wet mixing with water effectively prevents the fibers in the modified reinforcing material from agglomerating upon contact with water, thus ensuring uniform fiber dispersion in the slurry. In addition, subsequent vibration degassing effectively eliminates air bubbles in the slurry, reducing internal defects in the finished door core panel and improving its strength and uniformity.

[0033] In one feasible implementation, in S1, the temperature for calcining the phosphogypsum and desulfurized gypsum is 140-180℃, and the calcination time is 2-4 hours; the particle size of the mixed powder is 200-300 mesh; the first temperature is 80-120℃, the first rotation speed is 1000-1500 r / min, and the first duration is 10-20 min; the second rotation speed is 500-800 r / min, and the second duration is 15-30 min.

[0034] In one feasible implementation, in S2, the ultrasonic cleaning power is 200-300W, and the ultrasonic cleaning time is 10-20min; the drying temperature is 80-100℃, and the drying time is 2-4h; the third rotation speed is 400-600r / min, and the third duration is 5-10min; the second temperature is 60-90℃, and the fourth duration is 20-40min.

[0035] In one feasible implementation, in S3, the fourth rotational speed is 800-1200 r / min, and the fifth duration is 3-8 min; the fifth rotational speed is 1200-1800 r / min, and the sixth duration is 5-15 min.

[0036] In one feasible implementation, in S4, the vibration frequency of the vibratory venting is 30-50Hz, the amplitude is 0.2-0.5mm, and the vibration duration is 30-60s; the initial setting time is 20-40min (starting from the beginning of pouring); the core-pulling method is horizontal coaxial uniform core-pulling with a core-pulling speed of 0.1m / s; and the final setting time is 60-90min (starting from the beginning of pouring).

[0037] Beneficial technical effects:

[0038] This application provides a method for preparing hollow fireproof gypsum door core panels. The process is simple and controllable, requires no complex equipment, produces stable product quality, and is suitable for large-scale industrial production, offering significant economic and environmental benefits. Specifically, this application uses a modified cementitious material obtained by calcining a mixture of phosphogypsum and desulfurized gypsum, followed by dual modification with an aluminate coupling agent and redispersible latex powder. This not only increases the total utilization rate of industrial by-product gypsum to 75%-95%, significantly reducing dependence on natural gypsum resources and production costs, but also significantly improves the toughness and adhesion of the modified cementitious material used as the matrix material for gypsum door core panels. A strong bond is established between the fibers and the gypsum matrix through a reinforcing system composed of chopped glass fibers and rock wool fibers, surface-modified with a silane coupling agent. This fully leverages the synergistic reinforcing effect of the two fibers, improving the flexural strength and impact resistance of the door core panel. Furthermore, this application achieves weight reduction while ensuring the mechanical properties and fireproof and heat-insulating performance of the door core panel through an optimized hollow structure design. Attached Figure Description

[0039] Figure 1 This is a physical image of the hollow fireproof gypsum board provided in this application.

[0040] Figure 2 This is a flowchart illustrating the preparation method of the hollow fireproof gypsum door core board provided in this application. Detailed Implementation

[0041] To facilitate understanding of the content described in this application, the technical solutions described herein are further explained below with reference to specific embodiments; however, this application is not limited thereto. All equivalent transformations or simple substitutions made based on the substantive content of this application should fall within the protection scope of this application.

[0042] The singular forms “for,” “or,” “a,” “any,” and “the” used in this application are intended to include the plural forms unless the context clearly indicates otherwise.

[0043] The following describes in detail, with reference to different embodiments, a method for preparing a hollow fireproof gypsum door core board provided in this application.

[0044] The hollow fireproof gypsum board prepared in the embodiments and comparative examples of this application has a length of 2100mm, a width of 900mm, and a thickness of 48mm; each end of the board has a solid side edge 18mm wide; 15 through holes with isosceles trapezoidal cross-sections are arranged in a single row at equal intervals along the width of the board; the height of each isosceles trapezoid is 30mm, one base is 45mm, and the other base is 47mm; the through holes extend along the length of the board. The actual product is as follows: Figure 1 As shown;

[0045] The particle size of the mixed powder obtained after grinding in step S1 of each embodiment and comparative example is 200-300 mesh.

[0046] Example 1

[0047] like Figure 2 As shown, a method for preparing a hollow fireproof gypsum door core board includes the following steps:

[0048] S1. Phosphogypsum and desulfurized gypsum are mixed and calcined at 140℃ for 4 hours, then ground into a mixed powder and put into a mixing device. Isopropyl distearate aluminate is then added to the mixture and stirred at 80℃ and 1000r / min for 10 minutes. Ethylene-vinyl acetate copolymer is then added and stirred at 500r / min for 15 minutes. The mixture is then cooled to room temperature and discharged to obtain the modified cementitious material.

[0049] The mass ratio of phosphogypsum, desulfurized gypsum, isopropyl distearate aluminate, and ethylene-vinyl acetate copolymer is 60:30:0.5:9.5.

[0050] S2. Short glass fibers with a length of 3 mm and rock wool fibers with a length of 5 mm were ultrasonically cleaned with ethanol at a power of 200 W for 10 min, filtered, and dried at 80℃ for 2 h to obtain pretreated short glass fibers and pretreated rock wool fibers. Then, the pretreated short glass fibers and pretreated rock wool fibers were put into a mixing device and stirred at 400 r / min for 5 min at room temperature. Then, 7-octenyltrimethoxysilane dispersion was sprayed into the mixture while stirring. The mixture was stirred at 400 r / min at 60℃ for 20 min. Then, the mixture was cooled to room temperature and discharged to obtain the modified reinforced material.

[0051] The mass ratio of chopped glass fiber to rock wool fiber is 20:80; the amount of 7-octenyltrimethoxysilane dispersion is 0.5% of the total mass of chopped glass fiber and rock wool fiber; the composition of 7-octenyltrimethoxysilane dispersion includes 7-octenyltrimethoxysilane, ethanol and water, and the mass ratio of 7-octenyltrimethoxysilane, ethanol and water is 15:65:20.

[0052] S3. Weigh the modified cementitious material, modified reinforcing material, expanded perlite, sodium dodecyl sulfate, polycarboxylate superplasticizer, citric acid and calcium stearate according to the proportion, put them into the mixing equipment, stir at 800 r / min for 3 min at room temperature, then add water and stir at 1200 r / min for 5 min to obtain the mixed slurry.

[0053] The mass ratio of modified cementitious material, modified reinforcing material, expanded perlite, sodium dodecyl sulfate, polycarboxylate superplasticizer, citric acid, and calcium stearate is 60:15:24.1:0.1:0.2:0.1:0.5; the mass of water is 30% of the total mass of other raw materials.

[0054] S4. Pour the mixed slurry into a mold with a detachable core mold, vibrate at a frequency of 30Hz and an amplitude of 0.5mm for 60s to remove air, allow 20 minutes for initial setting (starting from the start of pouring), remove the core at a horizontal coaxial speed of 0.1m / s, and demold after 60 minutes for final setting (starting from the start of pouring) to obtain a hollow fireproof gypsum door core board.

[0055] Example 2

[0056] like Figure 2 As shown, a method for preparing a hollow fireproof gypsum door core board includes the following steps:

[0057] S1. Phosphogypsum and desulfurized gypsum are mixed and calcined at 180°C for 2 hours, then ground into a mixed powder and fed into a mixing device. Isopropyl distearate aluminate is then added to the mixture and stirred at 120°C and 1500 r / min for 20 minutes. Acrylic ester copolymer is then added and stirred at 800 r / min for 30 minutes. The mixture is then cooled to room temperature and discharged to obtain the modified cementitious material.

[0058] The mass ratio of phosphogypsum, desulfurized gypsum, isopropyl distearate aluminate and acrylate copolymer is 70:18:2:10.

[0059] S2. Short glass fibers with a length of 12 mm and rock wool fibers with a length of 8 mm were ultrasonically cleaned with ethanol at a power of 300 W for 20 min, filtered, and dried at 100℃ for 4 h to obtain pretreated short glass fibers and pretreated rock wool fibers. Then, the pretreated short glass fibers and pretreated rock wool fibers were put into a mixing device and stirred at 600 r / min for 10 min at room temperature. Then, n-octyltrimethoxysilane dispersion was sprayed into the mixture while stirring. The mixture was stirred at 600 r / min at 90℃ for 40 min. The mixture was then cooled to room temperature and discharged to obtain the modified reinforced material.

[0060] The mass ratio of chopped glass fiber to rock wool fiber is 40:60; the amount of n-octyltrimethoxysilane dispersion is 1.5% of the total mass of chopped glass fiber and rock wool fiber; the composition of n-octyltrimethoxysilane dispersion includes n-octyltrimethoxysilane, ethanol and water, and the mass ratio of n-octyltrimethoxysilane, ethanol and water is 20:50:30.

[0061] S3. Weigh the modified cementitious material, modified reinforcing material, vitrified microspheres, sodium fatty alcohol polyoxyethylene ether sulfate, polycarboxylate superplasticizer, tartaric acid and zinc stearate according to the proportion, put them into the mixing equipment, stir at 1200 r / min for 8 min at room temperature, then add water and stir at 1800 r / min for 15 min to obtain the mixed slurry.

[0062] The mass ratio of modified cementitious material, modified reinforcing material, vitrified microspheres, sodium fatty alcohol polyoxyethylene ether sulfate, polycarboxylate superplasticizer, tartaric acid, and zinc stearate is 80:5:12.2:0.5:1:0.5:0.8; the mass of water is 50% of the total mass of other raw materials.

[0063] S4. Pour the mixed slurry into a mold with a detachable core mold, vibrate at a frequency of 50Hz and an amplitude of 0.2mm for 30s to remove air, allow 40 minutes for initial setting (starting from the start of pouring), remove the core at a horizontal coaxial speed of 0.1m / s, and demold after 90 minutes for final setting (starting from the start of pouring) to obtain a hollow fireproof gypsum door core board.

[0064] Example 3

[0065] like Figure 2 As shown, a method for preparing a hollow fireproof gypsum door core board includes the following steps:

[0066] S1. Phosphogypsum and desulfurized gypsum are mixed and calcined at 160℃ for 3 hours, then ground into a mixed powder and put into a mixing device. Isopropyl distearate isopropyl bis(aluminopropylidene) is added to the mixture and stirred at 95℃ and 1200r / min for 15 minutes. Then styrene-butadiene copolymer is added and stirred at 650r / min for 22 minutes. The mixture is then cooled to room temperature and discharged to obtain the modified cementitious material.

[0067] The mass ratio of phosphogypsum, desulfurized gypsum, isopropyl distearate aluminate and styrene-butadiene copolymer is 70:23:2:5.

[0068] S2. Short glass fibers with a length of 7 mm and rock wool fibers with a length of 6 mm were ultrasonically cleaned with ethanol at a power of 250 W for 15 min, filtered, and dried at 90℃ for 3 h to obtain pretreated short glass fibers and pretreated rock wool fibers. Then, the pretreated short glass fibers and pretreated rock wool fibers were put into a mixing device and stirred at 500 r / min for 7 min at room temperature. Then, aniline methyltrimethoxysilane dispersion was sprayed into the mixture while stirring. The mixture was stirred at 500 r / min at 75℃ for 30 min. Then, the mixture was cooled to room temperature and discharged to obtain the modified reinforced material.

[0069] The mass ratio of chopped glass fiber to rock wool fiber is 30:70; the amount of aniline methyltrimethoxysilane dispersion is 1% of the total mass of chopped glass fiber and rock wool fiber; the composition of aniline methyltrimethoxysilane dispersion includes aniline methyltrimethoxysilane, ethanol and water, and the mass ratio of aniline methyltrimethoxysilane, ethanol and water is 17.5:57.5:25;

[0070] S3. Weigh the modified cementitious material, modified reinforcing material, fly ash, sodium α-olefin sulfonate, polycarboxylate superplasticizer, borax and calcium stearate according to the proportion, put them into the mixing equipment, stir at 1000 r / min for 5 min at room temperature, then add water and stir at 1500 r / min for 10 min to obtain the mixed slurry.

[0071] The mass ratio of modified cementitious material, modified reinforcing material, fly ash, sodium α-olefin sulfonate, polycarboxylate superplasticizer, borax, and calcium stearate is 70:10:17.7:0.3:0.6:0.3:1.1; the mass of water is 40% of the total mass of other raw materials.

[0072] S4. Pour the mixed slurry into a mold with a detachable core mold, vibrate at a frequency of 40Hz and an amplitude of 0.3mm for 45s to remove air, allow 30 minutes for initial setting (starting from the start of pouring), remove the core at a horizontal coaxial speed of 0.1m / s, and demold after 80 minutes for final setting (starting from the start of pouring) to obtain a hollow fireproof gypsum door core board.

[0073] Example 4

[0074] like Figure 2 As shown, a method for preparing a hollow fireproof gypsum door core board includes the following steps:

[0075] S1. Phosphogypsum and desulfurized gypsum are mixed and calcined at 150°C for 3.5 hours, then ground into a mixed powder and fed into a mixing device. Isopropyl distearate aluminate is then added to the mixture and stirred at 90°C and 1100 r / min for 12 minutes. Ethylene-vinyl acetate copolymer is then added and stirred at 550 r / min for 18 minutes. The mixture is then cooled to room temperature and discharged to obtain the modified cementitious material.

[0076] The mass ratio of phosphogypsum, desulfurized gypsum, isopropyl distearate aluminate, and ethylene-vinyl acetate copolymer is 62:28:0.8:9.2.

[0077] S2. Short glass fibers with a length of 5 mm and rock wool fibers with a length of 7 mm were ultrasonically cleaned with ethanol at a power of 220 W for 12 min, filtered, and dried at 85℃ for 2.5 h to obtain pretreated short glass fibers and pretreated rock wool fibers. Then, the pretreated short glass fibers and pretreated rock wool fibers were put into a mixing device and stirred at 450 r / min for 6 min at room temperature. Then, 7-octenyltrimethoxysilane dispersion was sprayed into the mixture while stirring. The mixture was stirred at 450 r / min at 70℃ for 25 min. Then, the mixture was cooled to room temperature and discharged to obtain the modified reinforced material.

[0078] The mass ratio of chopped glass fiber to rock wool fiber is 25:75; the amount of 7-octenyltrimethoxysilane dispersion is 0.7% of the total mass of chopped glass fiber and rock wool fiber; the composition of 7-octenyltrimethoxysilane dispersion includes 7-octenyltrimethoxysilane, ethanol and water, and the mass ratio of 7-octenyltrimethoxysilane, ethanol and water is 16:62:22;

[0079] S3. Weigh the modified cementitious material, modified reinforcing material, expanded perlite, sodium dodecyl sulfate, polycarboxylate superplasticizer, citric acid and zinc stearate according to the proportion, put them into the mixing equipment, stir at 900 r / min for 4 min at room temperature, then add water and stir at 1300 r / min for 7 min to obtain the mixed slurry.

[0080] The mass ratio of modified cementitious material, modified reinforcing material, expanded perlite, sodium dodecyl sulfate, polycarboxylate superplasticizer, citric acid, and zinc stearate is 65:12:19.6:0.2:0.4:0.2:2; the mass of water is 35% of the total mass of other raw materials.

[0081] S4. Pour the mixed slurry into a mold with a detachable core mold, vibrate at a frequency of 35Hz and an amplitude of 0.4mm for 50s to remove air, allow 35 minutes for initial setting (starting from the start of pouring), remove the core at a horizontal coaxial speed of 0.1m / s, and demold after 70 minutes for final setting (starting from the start of pouring) to obtain a hollow fireproof gypsum door core board.

[0082] Example 5

[0083] like Figure 2 As shown, a method for preparing a hollow fireproof gypsum door core board includes the following steps:

[0084] S1. Phosphogypsum and desulfurized gypsum are mixed and calcined at 165℃ for 2.5h, then ground into a mixed powder and put into a mixing device. Isopropyl distearate isopropyl acetoalkoxy aluminate is added to it and stirred at 110℃ and 1400r / min for 18min. Then acrylate copolymer is added and stirred at 750r / min for 28min. The mixture is then cooled to room temperature and discharged to obtain the modified cementitious material.

[0085] The mass ratio of phosphogypsum, desulfurized gypsum, isopropyl distearate aluminate, and acrylate copolymer is 68:22:1.5:8.5.

[0086] S2. Short glass fibers with a length of 10 mm and rock wool fibers with a length of 6 mm were ultrasonically cleaned with ethanol at a power of 280 W for 18 min, filtered, and dried at 95 °C for 3.5 h to obtain pretreated short glass fibers and pretreated rock wool fibers. Then, the pretreated short glass fibers and pretreated rock wool fibers were put into a mixing device and stirred at 550 r / min for 9 min at room temperature. Then, n-octyltrimethoxysilane dispersion was sprayed into the mixture while stirring. The mixture was stirred at 550 r / min at 85 °C for 35 min. Then, the mixture was cooled to room temperature and discharged to obtain the modified reinforced material.

[0087] The mass ratio of chopped glass fiber to rock wool fiber is 35:65; the amount of n-octyltrimethoxysilane dispersion is 1.2% of the total mass of chopped glass fiber and rock wool fiber; the composition of n-octyltrimethoxysilane dispersion includes n-octyltrimethoxysilane, ethanol and water, and the mass ratio of n-octyltrimethoxysilane, ethanol and water is 19:53:28.

[0088] S3. Weigh the modified cementitious material, modified reinforcing material, vitrified microspheres, sodium fatty alcohol polyoxyethylene ether sulfate, polycarboxylate superplasticizer, tartaric acid and calcium stearate according to the proportion, put them into the mixing equipment, stir at 1100 r / min for 7 min at room temperature, then add water and stir at 1700 r / min for 13 min to obtain the mixed slurry.

[0089] The mass ratio of modified cementitious material, modified reinforcing material, vitrified microspheres, sodium fatty alcohol polyoxyethylene ether sulfate, polycarboxylate superplasticizer, tartaric acid, and calcium stearate is 75:8:14.4:0.4:0.8:0.4:1; the mass of water is 45% of the total mass of other raw materials.

[0090] S4. Pour the mixed slurry into a mold with a detachable core mold, vibrate at a frequency of 45Hz and an amplitude of 0.3mm for 40s to remove air, allow 25 minutes for initial setting (starting from the start of pouring), remove the core at a horizontal coaxial speed of 0.1m / s, and demold after 75 minutes for final setting (starting from the start of pouring) to obtain a hollow fireproof gypsum door core board.

[0091] Example 6

[0092] like Figure 2 As shown, a method for preparing a hollow fireproof gypsum door core board includes the following steps:

[0093] S1. Phosphogypsum and desulfurized gypsum are mixed and calcined at 170℃ for 2 hours, then ground into a mixed powder and fed into a mixing device. Isopropyl distearate is added to the mixture, and it is stirred at 95℃ and 1300 r / min for 14 minutes. Then, styrene-butadiene copolymer is added, and it is stirred at 700 r / min for 25 minutes. The mixture is then cooled to room temperature and discharged to obtain the modified cementitious material. The mass ratio of phosphogypsum, desulfurized gypsum, isopropyl distearate, and styrene-butadiene copolymer is 66:24:1:9.

[0094] S2. Short glass fibers with a length of 8 mm and rock wool fibers with a length of 7 mm were ultrasonically cleaned with ethanol at a power of 260 W for 16 min, filtered, and dried at 88℃ for 3 h to obtain pretreated short glass fibers and pretreated rock wool fibers. Then, the pretreated short glass fibers and pretreated rock wool fibers were put into a mixing device and stirred at 520 r / min for 8 min at room temperature. Then, aniline methyltrimethoxysilane dispersion was sprayed into the mixture while stirring. The mixture was stirred at 520 r / min at 80℃ for 32 min. The mixture was then cooled to room temperature and discharged to obtain the modified reinforced material.

[0095] The mass ratio of chopped glass fiber to rock wool fiber is 28:72; the amount of aniline methyltrimethoxysilane dispersion is 0.9% of the total mass of chopped glass fiber and rock wool fiber; the composition of aniline methyltrimethoxysilane dispersion includes aniline methyltrimethoxysilane, ethanol and water, and the mass ratio of aniline methyltrimethoxysilane, ethanol and water is 18:58:24.

[0096] S3. Weigh the modified cementitious material, modified reinforcing material, fly ash, sodium α-alkenyl sulfonate, polycarboxylate superplasticizer, borax, and zinc stearate according to the specified proportions, and add them to a mixing device. Stir at 1050 r / min for 6 min at room temperature, then add water and stir at 1600 r / min for 12 min to obtain a mixed slurry. The mass ratio of the modified cementitious material, modified reinforcing material, fly ash, sodium α-alkenyl sulfonate, polycarboxylate superplasticizer, borax, and zinc stearate is 72:9:16.3:0.35:0.7:0.35:1.3; the mass of water is 42% of the total mass of other raw materials.

[0097] S4. Pour the mixed slurry into a mold with a detachable core mold, vibrate at a frequency of 35Hz and an amplitude of 0.2mm for 50s to remove air, allow 35 minutes for initial setting (starting from the start of pouring), remove the core at a horizontal coaxial speed of 0.1m / s, and demold after 90 minutes for final setting (starting from the start of pouring) to obtain a hollow fireproof gypsum door core board.

[0098] Comparative Example 1

[0099] This comparative example provides a method for preparing a hollow fireproof gypsum door core board. The difference between this comparative example and Example 3 is that the mixed powder of phosphogypsum and desulfurized gypsum is not modified with aluminate in this comparative example. Other process parameters and operating steps are exactly the same as in Example 3.

[0100] Comparative Example 2

[0101] This comparative example provides a method for preparing a hollow fireproof gypsum door core board. The difference between this comparative example and Example 3 is that the pretreated chopped glass fibers and pretreated rock wool fibers were not modified with silane coupling agents. Other process parameters and operating steps are exactly the same as in Example 3.

[0102] Comparative Example 3

[0103] This comparative example provides a method for preparing a hollow fireproof gypsum door core board. The difference between this comparative example and Example 3 is that this comparative example does not modify the mixed powder of phosphogypsum and desulfurized gypsum with aluminate, nor does it modify the pretreated chopped glass fibers and pretreated rock wool fibers with silane coupling agent. Other process parameters and operating steps are exactly the same as in Example 3.

[0104] Performance testing:

[0105] The density, flexural strength and fire resistance of the hollow fireproof gypsum door core boards prepared in Examples 1-6 and Comparative Examples 1-3 were tested.

[0106] The density and flexural strength of the hollow fire-resistant gypsum board core panels prepared in Examples 1-6 and Comparative Examples 1-3 were tested according to GB / T 5486-2008; the fire resistance performance of the hollow fire-resistant gypsum board core panels prepared in Examples 1-6 and Comparative Examples 1-3 was tested according to GB 12955-2024. Samples were prepared according to the requirements of the corresponding national standards, and the test conditions were consistent with the requirements of the corresponding national standards. The test results are shown in Table 1.

[0107] Table 1. Test results of hollow fireproof gypsum board core panels prepared in Examples 1-6 and Comparative Examples 1-3.

[0108]

[0109] As shown in Table 1, the mechanical properties and flexural and fire-resistant properties of Examples 1-6 are generally better than those of Comparative Examples 1-3.

[0110] The main reason is that in the hollow fireproof gypsum door core boards prepared in Examples 1-6, a modified cementitious material is obtained by calcining a mixture of phosphogypsum and desulfurized gypsum and then modifying it with an aluminate coupling agent and redispersible latex powder. This not only increases the total utilization rate of industrial by-product gypsum to 75%-95% of the modified cementitious material, significantly reducing dependence on natural gypsum resources and production costs, but also significantly improves the toughness and adhesion of the modified cementitious material as the matrix material of the gypsum door core board. Through the reinforcement system of short-cut glass fiber and rock wool fiber mixed and surface modified with silane coupling agent, a strong bond is built between the fiber and the gypsum matrix, giving full play to the synergistic reinforcement effect of the two fibers, thereby improving the flexural strength and impact resistance of the door core board. Moreover, this application also achieves weight reduction while ensuring the mechanical properties and fireproof and heat insulation performance of the door core board through optimized hollow structure design.

[0111] In contrast, in Comparative Example 1, the mixed powder of phosphogypsum and desulfurized gypsum was not modified with aluminate, resulting in poor compatibility between the gypsum powder and the redispersible latex powder. The redispersible latex powder could not form a continuous and uniform polymer film, and the matrix had many internal pores and insufficient adhesion, thus reducing the flexural strength of the resulting door core board.

[0112] In Comparative Example 2, the pretreated chopped glass fibers and pretreated rock wool fibers were not modified with silane coupling agents. The interfacial bonding between the fibers and the gypsum matrix was weak. Under external force, the fibers were easily pulled out of the matrix and could not effectively transfer stress and prevent crack propagation. Therefore, the flexural strength of the resulting door core board also decreased.

[0113] In Comparative Example 3, neither the aluminate modification of the mixed powder of phosphogypsum and desulfurized gypsum nor the silane coupling agent modification of the pretreated chopped glass fibers and pretreated rock wool fibers were performed, resulting in the worst flexural strength of the door core board.

[0114] Since the raw materials used in the three comparative examples are basically the same, the main difference lies in whether or not they are modified. Therefore, the density and fire resistance of the door core panels produced in the three comparative examples do not change much.

[0115] The above results demonstrate and describe the basic principles and main features of this application, as well as its advantages.

[0116] Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this application. Various changes and modifications can be made to this application without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of this application as claimed. The scope of protection of this application is defined by the equivalents of the appended claims.

Claims

1. A hollow fireproof gypsum board core panel, characterized in that, The raw materials for this door core panel include: modified cementitious material, modified reinforcing material, lightweight filler, foaming agent, water-reducing agent, retarder, moisture-proofing agent, and water; the modified cementitious material is prepared by calcining and grinding phosphogypsum and desulfurized gypsum into a mixed powder, then adding an aluminate coupling agent and redispersible latex powder to it; the calcination temperature is 140-180℃, and the calcination time is 2-4 hours; the particle size of the mixed powder is 200-300 mesh; The modified reinforcing material is obtained by pretreating and mixing chopped glass fibers and rock wool fibers, followed by surface modification with a silane coupling agent dispersion. In the modified reinforcing material, the mass ratio of chopped glass fibers to rock wool fibers is (20-40):(60-80); the length of the chopped glass fibers is 3-12 mm, and the length of the rock wool fibers is 5-8 mm. The amount of the silane coupling agent dispersion is 0.5-1.5% of the total mass of the chopped glass fibers and rock wool fibers. The composition of the silane coupling agent dispersion includes a silane coupling agent, ethanol, and water. The mass ratio of the silane coupling agent, ethanol, and water is (15-20):(50-65):(20-30). The silane coupling agent includes any one of 7-octenyltrimethoxysilane, n-octyltrimethoxysilane, and anilinemethyltrimethoxysilane. The mass ratio of the modified cementitious material, modified reinforcing material, lightweight filler, foaming agent, water-reducing agent, retarder, and moisture-proofing agent is (60-80):(5-15):(10-25):(0.1-0.5):(0.2-1):(0.1-0.5):(0.5-2); in the raw materials, the mass of water is 30-50% of the total mass of the other raw materials. In the modified cementitious material, the mass ratio of phosphogypsum, desulfurized gypsum, aluminate coupling agent and redispersible latex powder is (60-70):(15-30):(0.5-2):(5-10); the redispersible latex powder includes any one of ethylene-vinyl acetate copolymer, acrylate copolymer and styrene-butadiene copolymer.

2. A hollow fireproof gypsum board according to claim 1, characterized in that, The lightweight filler material includes any one or more of expanded perlite, vitrified microspheres, and fly ash; the foaming agent includes any one of sodium dodecyl sulfate, sodium fatty alcohol polyoxyethylene ether sulfate, and sodium α-alkenyl sulfonate; the water-reducing agent is a polycarboxylate water-reducing agent; the retarder includes any one of citric acid, tartaric acid, and borax; and the moisture-proofing agent includes any one of calcium stearate and zinc stearate.

3. A hollow fireproof gypsum board according to claim 1, characterized in that, The door core panel has solid side edges at both ends in the width direction, and through holes with isosceles trapezoidal cross sections are arranged in a single row at equal intervals along the width direction of the door core panel; the through holes are through the length direction of the door core panel.

4. A method for preparing a hollow fireproof gypsum board as described in any one of claims 1-3, characterized in that, Includes the following steps: S1. Phosphogypsum and desulfurized gypsum are mixed and calcined, cooled to room temperature, and ground into a mixed powder. Aluminate coupling agent is added to the mixture, and it is stirred for a first time at a first temperature and a first speed. Then, redispersible latex powder is added, and it is stirred for a second time at a second speed. The mixture is then cooled to room temperature and discharged to obtain a modified cementitious material. S2. The chopped glass fibers and rock wool fibers are ultrasonically cleaned with ethanol, filtered, and dried separately to obtain pretreated chopped glass fibers and pretreated rock wool fibers. Then, the pretreated chopped glass fibers and pretreated rock wool fibers are stirred and mixed at room temperature at a third speed for a third time. While stirring, a silane coupling agent dispersion is sprayed in. The stirring is continued at a third speed and a second temperature for a fourth time. The mixture is then cooled to room temperature and discharged to obtain the modified reinforced material. S3. Weigh the modified cementitious material, modified reinforcing material, lightweight filler, foaming agent, water-reducing agent, retarder and moisture-proofing agent according to the proportion, stir and mix at the fourth speed for a fifth time at room temperature, add water, and stir at the fifth speed for a sixth time to obtain the mixed slurry. S4. Pour the mixed slurry into a mold with a detachable core mold, vibrate to remove air, and then remove the core after initial setting and demold after final setting to obtain a hollow fireproof gypsum door core board.

5. The method for preparing a hollow fireproof gypsum door core board according to claim 4, characterized in that, In S1, the first temperature is 80-120℃, the first rotation speed is 1000-1500r / min, and the first duration is 10-20min; the second rotation speed is 500-800r / min, and the second duration is 15-30min.

6. The method for preparing a hollow fireproof gypsum door core board according to claim 4, characterized in that, In S2, the ultrasonic cleaning power is 200-300W, and the ultrasonic cleaning time is 10-20min; the drying temperature is 80-100℃, and the drying time is 2-4h; the third rotation speed is 400-600r / min, and the third duration is 5-10min; the second temperature is 60-90℃, and the fourth duration is 20-40min.

7. The method for preparing a hollow fireproof gypsum door core board according to claim 4, characterized in that, In S3, the fourth rotational speed is 800-1200 r / min, and the fifth duration is 3-8 min; the fifth rotational speed is 1200-1800 r / min, and the sixth duration is 5-15 min.

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