Preparation method of self-foaming filling type insulating brick
By injecting slurry of specific components into the holes of the bricks for foaming reaction, self-foaming and filling insulation bricks with porous structures are formed, which solves the problems of poor fire resistance and long production time of existing insulation bricks, and achieves a combination of high strength and good insulation performance.
Patent Information
- Application Number
- CN202510645767.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-19
- Publication Date
- 2025-08-15
AI Technical Summary
The existing insulation bricks have poor fire resistance, less strength improvement, and a long production time.
The self-foaming fill-type insulation brick preparation method is used to inject slurry composed of rice husk ash, modified sodium bicarbonate, bentonite, aluminum silicate fiber and calcium lignin sulfonate into the holes of the brick blank, and the foaming reaction is triggered by the residual temperature of the brick blank to form a porous structure. The foaming process is controlled with the double-layer cladding technology to ensure uniform distribution of bubbles.
It improves the fire resistance of insulation bricks, enhances compressive strength, and significantly reduces the thermal conductivity and heat storage coefficient, shortens the production time.
Smart Images
Figure CN120483740A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of thermal insulation brick devices, and in particular to a method for preparing self-foaming filling thermal insulation bricks. Background Art
[0002] With the increasing requirements for thermal insulation performance of exterior walls of energy-saving buildings and the need to reduce energy consumption of buildings, single-wall-thick (or full-wall-thick) sintered thermal insulation bricks / blocks have evolved from porous structures to ones with pores filled with inorganic thermal insulation materials.
[0003] Currently, the high-efficiency insulation materials used for filling mainly include expanded polystyrene foam boards (EPS / XPS), foamed polyurethane, glass wool, rock wool, mineral wool, etc. These materials are very effective in improving the thermal performance of insulation bricks / blocks, but they also have the problems of high cost, low fire resistance, and little improvement in strength and thermal insulation performance. Moreover, the current insulation bricks are filled with foam materials after the bricks are cooled, which takes a long time to produce. Summary of the Invention
[0004] The present invention aims to provide a method for preparing self-foaming filled insulation bricks with good fireproof effect, which solves the problems of poor fireproof effect, little strength improvement and long production time of existing insulation bricks.
[0005] The above technical problems are solved by the following technical solutions: A method for preparing self-foaming filling type insulation bricks, characterized by comprising the following steps:
[0006] S1: Sintering the bricks into shape, and taking them out of the kiln when they are cooled to 160-170°C. The bricks are hollow bricks with holes;
[0007] S2: injecting a self-expanding slurry into the holes of the brick, wherein the triggering temperature of the slurry is 150° C. The residual heat of the brick triggers the foaming reaction of the slurry, and the slurry fills the holes when foaming;
[0008] S3: Cooling the brick to room temperature to form a self-foaming filled insulation brick;
[0009] The slurry is composed of six components, namely, rice husk ash, modified sodium bicarbonate, bentonite, aluminum silicate fiber, calcium lignin sulfonate and water; the mass percentages of the six components are 20:5:10:4:1:10.
[0010] The calcium lignin sulfonate of the present invention is a high molecular polymer with multiple long molecular chains that easily ionizes in water to produce negatively charged ions. The ions adsorb on the surface of slurry particles, giving them a negative charge and preventing particle aggregation through electrostatic repulsion. The long-chain molecules adsorb on the surface of slurry particles to form a steric hindrance effect, further preventing particle agglomeration. The calcium lignin sulfonate acts as a dispersant to adjust the slurry viscosity and ensure the uniformity and fluidity of the slurry. The interfacial shear strength between the foam and the brick pore wall is ≥1.5 MPa. The comprehensive compressive strength of the filled insulation brick is increased by 45-50% compared to the unfilled state, the thermal conductivity is reduced by 70-80% compared to the unfilled state, and the heat storage coefficient is increased by 25-30% compared to the unfilled state. Using residual heat to trigger foaming allows foaming and cooling to proceed simultaneously, shortening the time required to produce the insulation brick.
[0011] Rice husk ash: contains 85% to 90% amorphous SiO2, which reacts with Al2O3 in bentonite at high temperature to form a silicate network and a porous skeleton. Porous structure (specific surface area ≥350m 2 / g) can block thermal radiation and reduce thermal conductivity.
[0012] Bentonite: Sodium bentonite expands when heated (expansion ratio ≥ 12mL / g) and forms a closed-pore structure in synergy with CO2 gas;
[0013] Aluminum silicate fiber: has low thermal conductivity, excellent thermal stability and chemical stability. The fiber forms a three-dimensional skeleton in the slurry to prevent the foam from collapsing. The fiber melting point is ≥1260℃, which enhances high-temperature stability.
[0014] Initial stage: Modified sodium bicarbonate decomposes under heat, releasing CO2 gas and forming a preliminary pore structure
[0015] 2NaHCO3→Na2CO3+CO2↑+H2O
[0016] Swelling stage: Bentonite absorbs water and swells, forming a gel network, which further strengthens the pore structure.
[0017] Na2SiO3·nH2O+H2O→Na2SiO3·(n+m)H2O
[0018] Skeleton formation stage: Aluminum silicate fibers combine with rice husk ash to form a stable three-dimensional network structure.
[0019] xAl2O3+ySiO2→Al 2x Si y O 3x+2y
[0020] Final stage: The gas (CO2) and gel network work together to form a multi-level pore structure, which significantly improves the thermal insulation performance.
[0021] The purpose of double-layer coating technology is to prevent sodium bicarbonate from overheating and decomposing prematurely, which would affect the foaming effect; by melting the outer layer of PLA and the inner layer of calcium stearate, sodium bicarbonate is gradually exposed at an appropriate temperature to ensure that it decomposes within the expected time and conditions.
[0022] Advantages of double-layer coating: Improved foaming uniformity. By controlling the decomposition time, bubbles are evenly distributed throughout the material, avoiding local overheating or bubbles that are too large or too small. Enhanced thermal insulation performance. The uniform and multi-level pore structure provides more effective insulation, improving the product's thermal insulation effect.
[0023] The inner layer material calcium stearate has the following characteristics: biodegradable, non-toxic, and suitable for material processing in high temperature environments.
[0024] The outer layer material polylactic acid (PLA) features: non-toxic, commonly used as a heat stabilizer and lubricant, with good lubricity and stability.
[0025] Sodium bicarbonate decomposes when exposed to heat to form an alkaline environment (OH - ) and react with the active ingredients in rice husk ash, such as amorphous SiO2, to generate silicate ions (SiO3 2- ), further promoting the formation of calcium silicate hydrate (CSH) gel.
[0026] 2NaHCO3→Na2CO3+H2O+CO2↑(forms alkaline environment)
[0027] SiO2+2OH - →SiO3 2- +2H2O
[0028] SiO3 2- +Ca 2+ +H2O→CaO·SiO2·H2O (CSH gel);
[0029] The raw materials of the foaming slurry are all composed of high-temperature refractory materials. After foaming, the fire resistance limit of the obtained insulation brick is not less than 5 hours (determined according to GB / T 9978-2008 standard), and no toxic gas is released at high temperature.
[0030] Preferably, the rice husk ash is pre-calcined at 450°C and has a specific surface area of ≥350m 2 / g. During the slurry foaming process, the SiO2 in the rice husk ash reacts with the free CaO in the brick body at the residual sintering temperature (160-170°C) to form calcium silicate hydrate (CSH) gel. Under the action of the expansion pressure generated by foaming, the CSH gel penetrates into the microcracks and pores of the brick body, forming a dense structure to prevent lime bursting, thereby improving the compressive strength of the brick and the interfacial shear strength between the foam and the pore wall.
[0031] Preferably, the bentonite is treated with sodium modification, and the sodium modification method is: adding 4% to 6% of the dry weight of the bentonite with sodium carbonate, aging in a water bath at 60 to 80°C for 24 to 48 hours, thereby forming sodium-based bentonite, and the expansion ratio of the sodium-based bentonite is ≥12mL / g. The modified sodium-based bentonite absorbs water and expands, generating expansion pressure to squeeze the pores of the slurry, thereby increasing the density of the foam, and synergizing with CO2 to form a closed-cell structure, reducing pore connectivity; at the same time, the free CaO generated during the reaction of rice husk ash reacts with water in the slurry to generate Ca(OH)2, which further dissociates to produce Ca 2+ , the Na in the sodium bentonite + With Ca 2+ Exchange occurs, forming an electrostatic adsorption layer, which makes the foam body and the pore wall interface closely bonded, improving the anti-stripping performance.
[0032] Preferably, the aluminum silicate fibers have the following performance indicators: fiber length 0.5-2.0 mm, diameter 8-15 μm, melting point ≥1760°C. The aluminum silicate fibers migrate and entangle with each other under the expansion and extrusion of the slurry foaming, forming a network structure that can effectively disperse and absorb external forces, reducing the expansion of cracks in the brick body; the distribution density of the aluminum silicate fibers in the foam is ≥20 fibers / mm 2 .
[0033] Preferably, the modified sodium bicarbonate is coated with a double layer, the inner layer being covered with calcium stearate and the outer layer being covered with polylactic acid (PLA). The inner layer of the modified sodium bicarbonate is covered with calcium stearate as a protective layer to control the release of sodium bicarbonate, with a thickness of 5 to 8 μm and a melting point of 140 to 150°C. After melting at high temperature, the sodium bicarbonate is exposed to a heat source; the outer layer of the modified sodium bicarbonate is covered with polylactic acid (PLA) as a sustained-release layer to prevent particle adhesion and physical damage, with a thickness of 2 to 3 μm and a melting point of 150 to 160°C, to prevent sodium bicarbonate from prematurely contacting an external heat source; the decomposition temperature of the double-layer coated sodium bicarbonate is 150°C.
[0034] Preferably, in step S2, the single-hole grouting rate is controlled at 5 to 10 mL / s, and the grouting volume is calculated according to the following formula:
[0035]
[0036] Where: Q is the grouting volume, in ml; V 孔洞 The volume of a single hole in the fired brick, in cm 3 ; E is the foaming ratio, which is adjusted by the sodium bicarbonate content; α is the temperature compensation coefficient; ΔT is the difference between the actual temperature of the brick body during grouting and the reference temperature (150°C), E and α are determined through experiments.
[0037] Preferably, in step S2, slurry is injected after the bricks are discharged from the kiln, and the temperature of the bricks is reduced from the kiln discharge temperature to the foaming triggering temperature (150° C.), and the foaming lasts for 2 to 5 minutes.
[0038] Preferably, charcoal particles are mixed into the bricks, and a dense layer is provided on the surface of the bricks, so that micropores are generated inside the bricks during sintering, and the foaming agent can enter the interior of the bricks after the micropores are generated, thereby further improving the thermal insulation and pressure resistance of the foamed bricks.
[0039] The invention has the following advantages: the produced thermal insulation bricks have good thermal insulation effect and fireproof effect, short production time and greatly increased strength. BRIEF DESCRIPTION OF THE DRAWINGS
[0040] Figure 1 Schematic diagram of a brick;
[0041] Figure 2 Schematic diagram of the self-foaming filled insulation brick produced.
[0042] In the figure: brick 1, hole 2, foam 3. DETAILED DESCRIPTION
[0043] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.
[0044] See also Figure 1 and Figure 2 A method for preparing a self-foaming filling type insulation brick is characterized by comprising the following steps:
[0045] S1: Sintering the brick 1 into a hollow brick with a hole 2, and cooling it to 160-170°C before taking it out of the kiln;
[0046] S2: injecting a self-expanding slurry into the holes of the brick, wherein the triggering temperature of the slurry is 150° C. The residual heat of the brick triggers the slurry to foam, and the slurry forms a foam 3 that fills the holes;
[0047] S3: Cooling the brick to room temperature to form a self-foaming filled insulation brick;
[0048] The slurry is composed of six components, namely, rice husk ash, modified sodium bicarbonate, bentonite, aluminum silicate fiber, calcium lignin sulfonate and water; the mass percentages of the six components are 20:5:10:4:1:10.
[0049] Rice husk ash is pre-calcined at 450℃, with a specific surface area of ≥350m 2 / g. During the slurry foaming process, the SiO2 in the rice husk ash reacts with the free CaO in the brick body at the residual sintering temperature (160-170°C) to form calcium silicate hydrate (CSH) gel. Under the action of the expansion pressure generated by foaming, the CSH gel penetrates into the microcracks and pores of the brick body, forming a dense structure to prevent lime bursting, thereby improving the compressive strength of the brick and the interfacial shear strength between the foam and the pore wall.
[0050] The bentonite is treated with sodium modification. The sodium modification method is as follows: adding 4% to 6% of sodium carbonate by dry weight of the bentonite and aging it in a water bath at 60 to 80°C for 24 to 48 hours to form sodium-based bentonite. The expansion ratio of the sodium-based bentonite is ≥12mL / g. The modified sodium-based bentonite absorbs water and expands, generating expansion pressure to squeeze the pores of the slurry, increase the density of the foam, and cooperate with CO2 to form a closed-cell structure, reducing pore connectivity. At the same time, the free CaO produced during the reaction of rice husk ash reacts with water in the slurry to generate Ca(OH)2, which further dissociates to produce Ca 2+ , the Na in the sodium bentonite + With Ca 2+ Exchange occurs, forming an electrostatic adsorption layer, which makes the foam body and the pore wall interface closely bonded, improving the anti-stripping performance.
[0051] Aluminum silicate fibers have the following performance indicators: fiber length 0.5-2.0mm, diameter 8-15μm, melting point ≥1760°C. Under the expansion and extrusion of the slurry foaming, the aluminum silicate fibers migrate and entangle with each other, forming a network structure that can effectively disperse and absorb external forces, reducing the expansion of cracks in the brick body; the distribution density of the aluminum silicate fibers in the foam is ≥20 fibers / mm 2 .
[0052] Preferably, the modified sodium bicarbonate is coated with a double layer, the inner layer being covered with calcium stearate and the outer layer being covered with polylactic acid (PLA). The inner layer of the modified sodium bicarbonate is covered with calcium stearate as a protective layer to control the release of sodium bicarbonate, with a thickness of 5 to 8 μm and a melting point of 140 to 150°C. After melting at high temperature, the sodium bicarbonate is exposed to a heat source; the outer layer of the modified sodium bicarbonate is covered with polylactic acid (PLA) as a sustained-release layer to prevent particle adhesion and physical damage, with a thickness of 2 to 3 μm and a melting point of 150 to 160°C, to prevent sodium bicarbonate from prematurely contacting an external heat source; the decomposition temperature of the double-layer coated sodium bicarbonate is 150°C.
[0053] In step S2, the single-hole grouting rate is controlled at 5-10 mL / s, and the grouting volume is calculated according to the following formula:
[0054]
[0055] Where: Q is the grouting volume, in ml; V is the volume of a single hole in the fired brick, in cm 3 ; E is the foaming ratio, which is adjusted by the sodium bicarbonate content; α is the temperature compensation coefficient; ΔT is the difference between the actual temperature of the brick body during grouting and the reference temperature (150°C), E and α are determined through experiments.
[0056] In step S2, slurry is injected after the bricks are taken out of the kiln, and the temperature of the bricks is reduced from the kiln temperature to the foaming triggering temperature (150°C), and the foaming lasts for 2 to 5 minutes.
[0057] Charcoal particles are mixed into the bricks, and a dense layer is provided on the surface of the bricks, which can generate micropores inside the bricks during sintering. After the micropores are generated, the foaming agent can enter the bricks, thereby further improving the thermal insulation and pressure resistance of the foamed bricks.
Claims
1. A method for preparing a self-foaming filling type insulation brick, characterized in that: The following steps are involved: S1: Sintering the bricks into shape, and taking them out of the kiln when they are cooled to 160-170°C. The bricks are hollow bricks with holes; S2: injecting a self-expanding slurry into the holes of the brick, wherein the triggering temperature of the slurry is 150° C. The residual heat of the brick triggers the foaming reaction of the slurry, and the slurry fills the holes when foaming; S3: Cooling the brick to room temperature to form a self-foaming filled insulation brick; The slurry is composed of six components: rice husk ash, modified sodium bicarbonate, bentonite, aluminum silicate fiber, calcium lignin sulfonate, and water; the mass percentages of the six components are 20:5:10:4:1:
10. The calcium lignin sulfonate is a high-molecular polymer with multiple long molecular chains that easily ionizes in water to produce negatively charged ions. The ions adsorb on the surface of the slurry particles, giving them a negative charge and preventing particle aggregation through electrostatic repulsion. The long-chain molecules adsorb on the surface of the slurry particles to form a steric hindrance effect, further preventing particle agglomeration. The calcium lignin sulfonate acts as a dispersant to adjust the slurry viscosity and ensure slurry uniformity and fluidity. The interfacial shear strength between the foam and the brick pore wall is ≥1.5 MPa. The comprehensive compressive strength of the filled insulation brick is increased by 45-50% compared to the unfilled brick, the thermal conductivity is reduced by 70-80%, and the heat storage coefficient is increased by 25-30% compared to the unfilled brick. Using residual heat to trigger foaming can enable foaming and cooling to proceed in parallel, shortening the time for making insulation bricks.
2. The method for preparing a self-foaming filled insulation brick according to claim 1, characterized in that: The rice husk ash is pre-calcined at 450°C and has a specific surface area of ≥350m 2 / g. During the slurry foaming process, the SiO2 in the rice husk ash reacts with the free CaO in the brick body at the residual sintering temperature (160-170°C) to form calcium silicate hydrate (CSH) gel. Under the action of the expansion pressure generated by foaming, the CSH gel penetrates into the microcracks and pores of the brick body, forming a dense structure to prevent lime bursting, thereby improving the compressive strength of the brick and the interfacial shear strength between the foam and the pore wall.
3. A method for preparing a self-foaming filled insulation brick according to claim 1 or 2, characterized in that: The bentonite is subjected to sodium modification treatment, and the sodium modification method is: adding 4% to 6% of sodium carbonate based on the dry weight of the bentonite, aging in a water bath at 60 to 80° C. for 24 to 48 hours, thereby forming sodium-based bentonite, and the expansion ratio of the sodium-based bentonite is ≥12 mL / g. The modified sodium bentonite absorbs water and expands, generating expansion pressure to squeeze the pores of the slurry, thereby increasing the density of the foam, and synergizing with CO2 to form a closed-cell structure, reducing pore connectivity; at the same time, the free CaO generated during the reaction of rice husk ash reacts with water in the slurry to generate Ca(OH)2, which further dissociates to generate Ca 2+ , the Na in the sodium bentonite + With Ca 2+ Exchange occurs, forming an electrostatic adsorption layer, which makes the foam body and the pore wall interface closely bonded, improving the anti-stripping performance.
4. A method for preparing a self-foaming filled insulation brick according to claim 1 or 2, characterized in that: The aluminum silicate fibers have the following performance indicators: fiber length 0.5-2.0 mm, diameter 8-15 μm, melting point ≥1760°C. Under the expansion and extrusion of the slurry foaming, the aluminum silicate fibers migrate and entangle with each other, forming a network structure that can effectively disperse and absorb external forces, reducing the expansion of cracks in the brick body; the distribution density of the aluminum silicate fibers in the foam is ≥20 fibers / mm 2 .
5. The method for preparing a self-foaming filled insulation brick according to claim 1 or 2, characterized in that: The modified sodium bicarbonate is coated with an inner and outer double layer, wherein the inner layer is coated with calcium stearate and the outer layer is coated with polylactic acid (PLA). The inner layer of the modified sodium bicarbonate is covered with calcium stearate as a protective layer to control the release of sodium bicarbonate. It has a thickness of 5 to 8 μm and a melting point of 140 to 150°C. After melting at high temperature, the sodium bicarbonate is able to contact the heat source. The outer layer of the modified sodium bicarbonate is covered with polylactic acid (PLA) as a sustained-release layer to prevent particle adhesion and physical damage. It has a thickness of 2 to 3 μm and a melting point of 150 to 160°C to prevent sodium bicarbonate from contacting external heat sources too early. The decomposition temperature of the double-layer coated sodium bicarbonate is 150°C.
6. A method for preparing a self-foaming filled insulation brick according to claim 1 or 2, characterized in that: In step S2, the single-hole grouting rate is controlled at 5-10 mL / s, and the grouting volume is calculated according to the following formula: Where: Q is the grouting volume, in ml; V 孔洞 The volume of a single hole in the fired brick, in cm 3 ; E is the expansion ratio, which is adjusted by the sodium bicarbonate content; α is the temperature compensation coefficient; ΔT is the difference between the actual temperature of the brick body during grouting and the reference temperature (150°C), and E and α are determined through experiments.
7. A method for preparing a self-foaming filled insulation brick according to claim 1 or 2, characterized in that: In step S2, slurry is injected after the bricks are taken out of the kiln, and the temperature of the bricks is reduced from the kiln temperature to the foaming triggering temperature (150° C.), and the foaming lasts for 2 to 5 minutes.
8. The method for preparing a self-foaming filled insulation brick according to claim 1 or 2, characterized in that: The bricks are mixed with charcoal particles and have a dense layer on their surface, which can generate micropores inside the bricks during sintering. After the micropores are generated, the foaming agent can enter the bricks, thereby further improving the thermal insulation and pressure resistance of the foamed bricks.