Plasticizable aluminum sol binder, method of making and use thereof

Abstract

The present application relates to the technical field of refractory materials, in particular to plastic combined with aluminum sol, a preparation method and application thereof, comprising the following raw materials by weight: corundum aggregate: 35-50 parts; corundum fine powder: 25-35 parts; active alumina micropowder: 8-15 parts; aluminum sol: 5-12 parts; block copolymer: 1.0-4.0 parts; humectant: 0.5-2.0 parts. The present application introduces polyacrylic acid-polypropylene oxide-polyacrylic acid block copolymer with A-B-A type three-block structure, utilizes the multi-tooth chemical coordination between the densely distributed carboxylic acid groups on the A chain segment and the aluminum ions on the surface of the aluminum sol particles, and the physical steric hindrance of the hydration layer formed by the fully stretched B chain segment at room temperature, to realize the double stabilization of the aluminum sol particles.

Description

Technical Field

[0001] This invention relates to the field of refractory materials technology, specifically to aluminum sol-bonded plastics, methods for preparing aluminum sol-bonded plastics, and the application of aluminum sol-bonded plastics in the repair of linings of medium-frequency induction furnaces. Background Technology

[0002] Medium-frequency induction furnaces are key equipment in the smelting of special steels and alloys, and the quality of their furnace lining materials directly determines the purity of the molten steel and the smelting efficiency. With the increasing demand for high-end metallic materials such as ultra-low carbon steel, ultra-low sulfur steel, and high-temperature alloys, the industry has imposed stringent requirements on furnace lining materials to be phosphorus-free and sulfur-free. Phosphorus and sulfur, as harmful impurities in steel, severely deteriorate the mechanical properties and corrosion resistance of steel. Especially in the field of special casting, increased phosphorus content can lead to fatal defects such as hot cracking in castings.

[0003] Traditional medium-frequency furnace linings commonly use phosphoric acid or phosphates as binders. While these provide good plasticity and room-temperature strength, they inevitably introduce phosphorus into the molten steel during service, failing to meet the technical requirements of high-end special metallurgy. To overcome the shortcomings of phosphorus-containing binders, the industry has explored phosphorus-free binding systems such as silica sol or alumina sol. Although silica sol binders are phosphorus-free, they introduce a large amount of SiO2, which readily reacts with Al2O3 in the material at high temperatures to form a low-melting-point phase, reducing the high-temperature strength and slag erosion resistance of the furnace lining. Alumina sol, due to its chemical composition being consistent with corundum aggregates, being phosphorus- and sulfur-free, and providing excellent high-temperature performance, has become the most promising alternative binder.

[0004] However, aluminum sol-bonded plastics face the challenge of an extremely short shelf life. Aluminum sol is an inorganic polymer solution with high chemical reactivity. Its nano-sized sol particles are highly susceptible to cross-linking and gelation during storage through condensation reactions, causing the slurry to harden and fail within days in sealed packaging. To extend shelf life, existing technologies employ the addition of small-molecule organic acids or polyols. Small-molecule organic acids, such as citric acid and oxalic acid, can only delay the gelation reaction by chemically chelating with aluminum ions through their carboxyl groups, but cannot address physical dehydration. Polyols, such as glycerol and ethylene glycol, can only slow down water evaporation by moisturizing, but have little effect on inhibiting chemical cross-linking between sol particles. Even when these two are combined, the extension of shelf life remains unsatisfactory. Furthermore, extending the static shelf life often comes at the cost of excessively inhibiting the system's reactivity, resulting in slow strength development, reduced plasticity, and difficulty in tamping or spreading during construction, severely impacting construction efficiency and furnace lining volume stability. Furthermore, existing additives operate at a constant or passive temperature throughout the entire temperature range from material storage to application, failing to detect and utilize temperature changes to actively regulate material rheological properties, making it difficult to achieve a balance between the contradictory requirements of long-term preservation and rapid activation for application. Summary of the Invention

[0005] This invention addresses the problems in the prior art by providing aluminum sol-bonded plastics, their preparation method, and their applications. The specific technical solution is as follows:

[0006] Aluminum sol-bonded plastic, comprising the following raw materials in parts by weight:

[0007] Corundum aggregate: 35-50 parts;

[0008] Corundum powder: 25-35 parts;

[0009] Activated alumina micro powder: 8-15 parts;

[0010] Aluminum sol: 5-12 parts;

[0011] Block copolymer: 1.0-4.0 parts;

[0012] Moisturizer: 0.5-2.0 parts;

[0013] The plastic has a phosphorus pentoxide content of less than 0.02 wt% and a sulfur trioxide content of less than 0.02 wt%.

[0014] The block copolymer is a copolymer with an ABA-type triblock structure, wherein the A segment is a polyacrylic acid segment, the B segment is a polypropylene oxide segment, the number average molecular weight is 8000-25000 g / mol, and the phase transition temperature of the B segment is 31-35℃.

[0015] As a further technical solution of the present invention, the phase transition temperature of the B segment is 33-35℃.

[0016] As a further technical solution of the present invention, the number average molecular weight of the block copolymer is 10000-20000 g / mol.

[0017] As a further technical solution of the present invention, the corundum aggregate comprises a continuous gradation consisting of at least two of the particle sizes of 5-3 mm, 3-1 mm and 1-0.088 mm.

[0018] As a further technical solution of the present invention, the particle size of the corundum fine powder is less than 0.088 mm;

[0019] The median diameter D50 of the activated alumina micro powder is 1.5-4.0 μm;

[0020] The aluminum sol has a solid content of 20-40% and a pH value of 3.0-5.0.

[0021] As a further technical solution of the present invention, the pH value of the aluminum sol is 3.8-4.5.

[0022] As a further technical solution of the present invention, the moisturizer is one or more of glycerin, sorbitol, and xylitol; the weight ratio of the moisturizer to the block copolymer is 1:(0.5-4).

[0023] Secondly, the present invention provides a method for preparing an aluminum sol-bonded plastic, comprising the following steps:

[0024] (1) Disperse the block copolymer and humectant in the aluminum sol and stir until homogeneous at a temperature at least 2°C lower than the phase transition temperature of the block copolymer and not higher than 30°C to obtain an active binding solution;

[0025] (2) The active binding liquid is mixed with the corundum aggregate, corundum fine powder and active alumina micro powder in a stirring device at a temperature at least 2°C lower than the phase change temperature of the block copolymer and not higher than 30°C to obtain wet mud.

[0026] (3) The wet mud is placed in a closed environment and left to stand for 12-24 hours at a temperature at least 2°C lower than the phase change temperature of the block copolymer and not higher than 30°C.

[0027] (4) After the material is trapped, it is squeezed and packaged to obtain the plastic.

[0028] As a further technical solution of the present invention, the temperature in steps (1) to (3) is controlled at 5-28℃.

[0029] Thirdly, the present invention also provides the application of aluminosilicate-bonded plastic in the repair of medium-frequency induction furnace linings.

[0030] The beneficial effects of this invention are as follows:

[0031] (1) In this invention, by introducing a polyacrylic acid-polypropylene oxide-polyacrylic acid block copolymer with an ABA-type triblock structure, the multidentate chemical coordination between the carboxylic acid groups densely distributed on the A segment and the aluminum ions on the surface of the aluminum sol particles, and the physical steric hindrance of the hydration layer formed by the B segment fully unfolding at room temperature, the dual stabilization of the aluminum sol particles is achieved, which solves the problem of short-term hardening failure caused by the continuous polycondensation and cross-linking of sol particles during sealed storage of aluminum sol-bonded plastics, and extends the effective shelf life of plastics from several days to more than twelve months of sealed storage at room temperature;

[0032] (2) In this invention, by designing the phase transition temperature of the B segment in the block copolymer to be close to the human body temperature range of 31-35℃, preferably 33-35℃, the heat generated by the rubbing of the hands of the construction personnel triggers the hydrophilic-hydrophobic phase transition of the B segment, causing the molecular chain to suddenly collapse from the extended state and release the bound free water, thereby realizing the plastic leap of the mud material at the moment of construction, solving the contradiction between long-term preservation and rapid construction activation of the existing aluminum sol bonding system, and the construction personnel can obtain good coating and tamping performance without adding extra water;

[0033] (3) In this invention, a block copolymer of pure organic polymer is used as the only functional additive. It is used to completely decompose and volatilize during baking at 200-400℃ and during use heating, leaving no harmful substances. At the same time, the micropore channels formed by the decomposition facilitate the smooth discharge of water vapor and gas, realizing the uniform sintering of the material after medium-temperature carbon removal and improving the crack resistance. It solves the problem of introducing phosphorus elements into the molten steel by traditional phosphorus-containing binders and the drawback of existing water-retaining agents affecting high-temperature performance. The product has a phosphorus pentoxide content of less than 0.02wt% and a sulfur trioxide content of less than 0.02wt%, meeting the stringent purity requirements of high-end special smelting.

[0034] (4) In this invention, by utilizing the structural feature of the ABA block sequence structure that connects the chelating functional segment and the temperature-sensitive functional segment in an orderly manner with covalent bonds, the chemical anchoring of the A segment on the surface of the alumina sol particles and the temperature-responsive phase transition behavior of the B segment are synergistically coupled, thereby achieving stable maintenance of the temperature-sensitive phase transition behavior in the harsh chemical environment of high ionic strength and multivalent aluminum ions in alumina sol. This solves the technical obstacle of ordinary temperature-sensitive polymers becoming unstable and precipitating in this type of system due to salting-out effect or cross-linking of metal ions, and breaks through the technical bottleneck of cross-domain application of temperature-sensitive polymers in the field of refractory plastics. Detailed Implementation

[0035] The present invention will be further described in detail below through specific embodiments, but the present invention is not limited to these embodiments. Unless otherwise specified, all parts refer to parts by weight.

[0036] Preparation of block copolymers

[0037] Preparation Example 1: In this preparation example, a PAA-b-PPO-b-PAA triblock copolymer with a number-average molecular weight of 15,200 and a phase transition temperature of 34°C was synthesized.

[0038] First, a PPO macromolecular chain transfer agent containing RAFT active groups at both ends was prepared: 20.0 g of hydroxyl-terminated polypropylene oxide (Mn = 10000 g / mol, 2.0 mmol) was dissolved in 80 mL of anhydrous tetrahydrofuran. Under nitrogen protection, 0.56 g of the symmetrical bifunctional RAFT chain transfer agent S,S'-bis(α,α'-dimethyl-α''-acetic acid) trithiocarbonate and 0.024 g of the catalyst 4-dimethylaminopyridine were added, followed by 0.82 g of... Dicyclohexylcarbodiimide was reacted at room temperature for 24 hours; the precipitate was removed by filtration, and the filtrate was concentrated by rotary evaporation, precipitated with n-hexane, and dried under vacuum to obtain a PPO macromolecular chain transfer agent with RAFT active groups at both ends, with an esterification rate greater than 95%; subsequently, 20.4 g of the above PPO macromolecular chain transfer agent was dissolved in 80 mL of dioxane, 4.32 g of acrylic acid and 0.033 g of azobisisobutyronitrile were added, the mixture was stirred to dissolve, and nitrogen was purged for 30 minutes to remove oxygen. The reaction was then carried out in an oil bath at 70 °C for 8 hours. After cooling, the reaction solution was precipitated with n-hexane and dried under vacuum to constant weight to obtain a PAA-b-PPO-b-PAA triblock copolymer; the product was determined by gel permeation chromatography, with a number average molecular weight Mn = 15200 g / mol and PDI = 1.25; the structure was confirmed by 1H NMR spectroscopy; and the phase transition temperature was determined by variable-temperature UV-Vis spectrophotometry at a wavelength of 500 nm and in a 1.0-wt% aqueous solution, with a phase transition temperature of 34.0 °C.

[0039] Preparation Example 2: In this preparation example, a PAA-b-PPO-b-PAA triblock copolymer with a number-average molecular weight of 8000 and a phase transition temperature of 31℃ was synthesized.

[0040] The method was similar to that used in Preparation Example 1, except that: 20.0 g of hydroxyl-terminated polypropylene oxide (Mn = 6000 g / mol, 3.33 mmol) was used as the starting material, and 0.93 g of a bifunctional RAFT chain transfer agent and 0.04 g of 4-dimethylaminopyridine were added for esterification to obtain a macromolecular chain transfer agent; then 22.0 g of this macromolecular chain transfer agent was dissolved in 80 mL of dioxane, and 18.0 g of acrylic acid and 0.055 g of azobisisobutyronitrile were added for polymerization; the resulting product had a number-average molecular weight Mn = 8000, a PDI = 1.28, and a phase transition temperature of 31.0 °C.

[0041] Preparation Example 3: In this preparation example, a PAA-b-PPO-b-PAA triblock copolymer with a number average molecular weight of 25,000 and a phase transition temperature of 35°C was synthesized.

[0042] The method was similar to that used in Preparation Example 1, except that: 30.0 g of hydroxyl-terminated polypropylene oxide (Mn = 15000 g / mol, 2.0 mmol) was used as the starting material, and 0.56 g of a bifunctional RAFT chain transfer agent and 0.024 g of 4-dimethylaminopyridine were added for esterification to obtain a macromolecular chain transfer agent; then 30.5 g of this macromolecular chain transfer agent was dissolved in 100-mL dioxane, and 2.0 g of acrylic acid and 0.033 g of azobisisobutyronitrile were added for polymerization; the resulting product had a number-average molecular weight Mn = 25000, a PDI = 1.30, and a phase transition temperature of 35.0 °C.

[0043] Example 1: An aluminum sol-bonded plastic, prepared by mixing the following raw materials in parts by weight:

[0044] The fused white corundum aggregate consists of 48 parts of continuous gradation composed of two particle sizes: 5-3mm and 3-1mm.

[0045] Fused white corundum fine powder, particle size less than 0.088 mm, 28 parts;

[0046] Active α-alumina micro powder, median diameter D50 of 2.5 μm, 12 parts;

[0047] Aluminum sol, solid content 30%, pH value 4.0, 10 parts;

[0048] Prepare 2.5 parts of the block copolymer synthesized in Example 1;

[0049] Glycerin, 1.5 parts.

[0050] The phosphorus pentoxide and sulfur trioxide contents in the selected corundum aggregates, corundum fine powders, and activated alumina micro powders are all no higher than 0.01 wt%.

[0051] The preparation method of this plastic is as follows: Under constant temperature of 20℃, glycerol and block copolymer are added sequentially to aluminum sol under stirring, and stirred at 200 rpm for 15 minutes to obtain a clear active binder; fused white corundum aggregate, fine powder and active α-alumina micro powder are added to a forced mixer and dry-mixed at 20℃ for 3 minutes; then, while maintaining stirring, the active binder is slowly added to the dry mix by spraying, and stirring is continued at 20℃ for 10 minutes to obtain a uniformly colored, hand-clump-forming moist clay; the moist clay is transferred to a sealed container and coated and cured at 20℃ for 24 hours; after curing, it is extruded into strips by a vacuum extruder and sealed in a vacuum aluminum-plastic composite bag to obtain the finished product.

[0052] Example 2: An aluminum sol-bonded plastic, prepared by mixing the following raw materials in parts by weight:

[0053] The fused white corundum aggregate consists of 35 parts of continuous gradation composed of three particle sizes: 5-3mm, 3-1mm, and 1-0.088mm.

[0054] Fused white corundum fine powder, particle size less than 0.088 mm, 35 parts;

[0055] Activated alumina micro powder, median diameter D50 of 3.5 μm, 15 parts;

[0056] Aluminum sol, solid content 35%, pH value 4.5, 7 parts;

[0057] 4.0 parts of the block copolymer synthesized in Example 2;

[0058] Glycerin, 2.0 parts.

[0059] The preparation method is as follows: At 15°C, glycerol and block copolymer are added sequentially to aluminum sol under stirring for 20 minutes to obtain an active binding liquid; corundum aggregate, fine powder and activated alumina micro powder are dry mixed for 4 minutes at an operating temperature of 15°C; then the active binding liquid is added and stirred at 15°C for 15 minutes to obtain a moist slurry; the slurry is placed in a sealed container and coated and cured at 15°C for 12 hours; vacuum extrusion molding and vacuum packaging are performed to obtain the finished product.

[0060] Example 3: An aluminum sol-bonded plastic, prepared by mixing the following raw materials in parts by weight:

[0061] Fused white corundum aggregate, consisting of a continuous gradation of two particle sizes, 5-3mm and 3-1mm, totaling 50 parts;

[0062] Fused white corundum fine powder, particle size less than 0.088 mm, 25 parts;

[0063] Activated alumina micro powder, median diameter D50 of 2.0 μm, 8 parts;

[0064] Aluminum sol, solid content 30%, pH value 3.8, 12 parts;

[0065] 1.0 part of the block copolymer synthesized in Preparation Example 3;

[0066] Xylitol, 2.0 parts.

[0067] The preparation method is as follows: at 28°C, xylitol and block copolymer are added sequentially to aluminum sol under stirring and stirred for 10 minutes to obtain an active binding liquid; corundum aggregate, fine powder and activated alumina micro powder are dry mixed for 3 minutes at an operating temperature of 28°C; then the active binding liquid is added and stirred for 10 minutes at 28°C to obtain a moist mud; the mud is coated and cured in a sealed container at 28°C for 20 hours; it is then vacuum extruded into strips and vacuum packaged to obtain the finished product.

[0068] Comparative Example 1: A traditional phosphate-bonded plastic, made from the following raw materials: 48 parts of fused white corundum aggregate, 28 parts of fused white corundum fine powder, 12 parts of activated alumina micro powder, 10 parts of 50% aluminum dihydrogen phosphate solution, and 5 parts of clay powder. The preparation method involves dry mixing the powders, adding the aluminum dihydrogen phosphate solution and stirring, allowing the mixture to stand for 24 hours, and then extruding and packaging it.

[0069] Comparative Example 2: An aluminum sol-bonded plastic without block copolymers. It differs from Example 1 in that the block copolymers and glycerol are removed, and the amount of aluminum sol is increased to 14 parts; the remaining components and preparation process are the same as in Example 1.

[0070] Comparative Example 3: A plasticizer in which a small molecule organic acid is used to replace the block copolymer. It differs from Example 1 in that 2.5 parts of the block copolymer are replaced with an equal amount of citric acid, 1.5 parts of glycerol are retained, and the remaining components and preparation process are the same as in Example 1.

[0071] Comparative Example 4: A plastic with a simple addition of humectant. It differs from Example 1 in that 2.5 parts of the block copolymer are replaced with an equal amount of glycerol, resulting in a total glycerol content of 4.0 parts. The remaining components and preparation process are the same as in Example 1.

[0072] Comparative Example 5: A plastic material using a homopolymer physical mixture. It differs from Example 1 in that 2.5 parts of block copolymer are replaced with a physical mixture of 1.5 parts of polyacrylic acid homopolymer (Mn≈5000) and 1.0 part of polypropylene oxide homopolymer (Mn≈10000), the amount of glycerin humectant remains unchanged, and the remaining components and preparation process are the same as in Example 1.

[0073] Comparative Example 6: A plastic material using a random copolymer. It differs from Example 1 in that 2.5 parts of block copolymer were replaced with an equal amount of PAA-co-PPO random copolymer (Mn≈15000, PAA to PPO mass ratio approximately 6:4, phase transition temperature approximately 36°C), the amount of glycerin humectant remained unchanged, and the remaining components and preparation process were the same as in Example 1.

[0074] Performance testing methods

[0075] The following provides a unified description of the performance testing methods for all the products obtained in the above embodiments and comparative examples, in order to facilitate evaluation and comparison.

[0076] Determination of plasticity index: Fill 500g of clay into a cylindrical standard mold with an inner diameter of 50mm and a height of 120mm. Use a 1kg hammer to drop freely from a height of 30cm to impact the sample surface. Record the number of impacts required to tamp the loose clay until its volume no longer changes significantly and the surface is smooth. The fewer the number of impacts, the better the plasticity. The principle of this method refers to the relevant provisions in GB / T2997 and YB / T 5119.

[0077] Accelerated preservation experiment: To simulate the effect of long-term storage, the sealed plastic was placed in a 40℃ constant temperature oven for 14 days. After taking it out, the plasticity index was tested according to the above method and compared with the initial plasticity index of the fresh sample. The plasticity index reduction rate was calculated; reduction rate = [(number of impacts after preservation - number of initial impacts) / number of initial impacts] × 100%.

[0078] Temperature-controlled plasticization experiment: Freshly prepared clay was kept at a constant temperature of 20℃ in a constant temperature room and at a constant temperature of 35℃ for 2 hours respectively. After being taken out, the plasticity index was tested immediately, and the plasticity index improvement rate at 35℃ compared with 20℃ was calculated. Improvement rate = [(number of impacts at 20℃ - number of impacts at 35℃) / number of impacts at 20℃] × 100%, and a positive value indicates plasticity improvement.

[0079] Direct verification experiment of kneading plasticization: Two portions of fresh clay were taken; the plasticity index of the first portion was tested after being kept at a constant temperature of 20℃ for 2 hours, and the number of impacts was recorded; the second portion was kneaded continuously for 60 seconds by construction workers wearing nitrile gloves with conventional tamping force, and the center temperature of the clay was recorded with an insertion thermocouple; immediately after kneading, the plasticity index was tested at 20℃, the number of impacts was recorded, and the kneading improvement rate was calculated.

[0080] Shear thinning control experiment: To distinguish the contributions of thermal and shear effects, fresh clay was placed in a kneader at a constant temperature of 20℃ and mechanically stirred at a rate of 30 rpm for 60 seconds to eliminate the heating effect of body temperature. The plasticity index was tested immediately after removal, and the number of impacts was recorded. The results were compared with the number of impacts after constant temperature treatment at 35℃ and the number of impacts after kneading to determine the main contributing mechanism of the plasticizing effect.

[0081] Temperature-controlled plasticization experiment after storage: The sample after the accelerated storage experiment was taken out and immediately kept at a constant temperature of 35℃ for 2 hours. Its plasticity index was tested and compared with the plasticity index of the sample at 20℃. The improvement rate was calculated to evaluate the ability of temperature-controlled activation characteristics to be retained after long-term storage.

[0082] High-temperature performance test: After drying the sample at 110℃ for 24 hours, it was heat-treated at 1600℃ in an oxidizing atmosphere for 3 hours, and the linear shrinkage rate after firing was tested; the high-temperature flexural strength test was carried out at 1400℃ in a carbon-embedded reducing atmosphere, and the sample was a strip sample pre-fired at 1600℃; the slag erosion resistance test adopted the static crucible method: a crucible hole with a diameter of 30 mm and a depth of 40 mm was drilled on the sample, filled with alkaline slag with a calcium oxide to silicon dioxide mass ratio of 1.5, and erosion test was carried out at 1600℃ under carbon-embedded conditions for 3 hours. After cooling, it was cut along the center line of the crucible and the maximum erosion depth was measured.

[0083] Chemical composition test: The sample was ground into powder after being heat-treated at 1600℃ for 3 hours, and the contents of phosphorus pentoxide and sulfur trioxide were detected by X-ray fluorescence spectroscopy.

[0084] Performance Test Results and Analysis

[0085] The test results of each embodiment and comparative example are summarized in Table 1 and Table 2; Table 1 shows the test results of accelerated storage, temperature-controlled plasticizing and kneading plasticizing, and Table 2 shows the test results of high-temperature performance and chemical composition.

[0086]

[0087] Table 1

[0088]

[0089] Table 2

[0090] Note: "-" in the table indicates that the sample has hardened and cannot be tested; the temperature-controlled plasticizing data of Comparative Examples 3 to 6 after storage were not tested because the sample condition had deteriorated significantly.

[0091] According to the results in Table 1, all examples remained soft and usable after 14 days of accelerated storage at 40°C, with a plasticity index decrease rate of only 9% to 18%, far lower than the 28% to 65% decrease in Comparative Examples 3 to 6, and none exhibited the complete hardening phenomenon seen in Comparative Example 2. This fully demonstrates that the block copolymer defined in this invention does indeed achieve long-term stability of sol particles in the harsh chemical environment of aluminum sol through a dual mechanism of chemical anchoring and physical steric hindrance.

[0092] In terms of workability, Examples 1 to 3 exhibited a unique hand-temperature activation effect: after being treated at a constant temperature of 35°C, the plasticity improvement rate reached 40.0% to 50.0%; after hand kneading for 60 seconds, the improvement rate also reached 28.6% to 37.5%. The kneading temperature rise experiment showed that the core temperature of the clay material in Example 1 could rise to approximately 36.8°C after kneading for 60 seconds, exceeding the phase transition temperature of its copolymer at 34°C, confirming that hand temperature was sufficient to trigger the hydrophilic-hydrophobic phase transition of the B-segment, thereby releasing free water and achieving a plasticity leap. The shear-thinning control experiment further clarified that after mechanical stirring at 20°C for 60 seconds, the plasticity index of Example 1 only decreased from 8 to 7 times, with an improvement rate of approximately 12.5%, far less than the effect triggered by temperature or kneading. This strongly demonstrates that the workability activation of this invention is mainly driven by temperature-induced segment conformational phase transitions, rather than simple shear-thinning.

[0093] Crucially, the results of Comparative Examples 5 and 6 confirm the irreplaceable nature of the block sequence structure from different perspectives. Comparative Example 5 used a physical mixture of two homopolymers, while Comparative Example 6 used a copolymer with the same composition but a random sequence. Neither showed any plasticizing effect at 35°C; in fact, Comparative Example 5 exhibited plastic degradation. This clearly demonstrates that only when the chelating A-segment and the thermosensitive B-segment are covalently and orderly linked to form a block structure can an ordered "chemically anchored plus physically shielded" dual network be formed on the surface of the nanosol particles, achieving synergistic segment collapse and free water release under temperature stimulation. Neither homopolymers nor random copolymers alone can construct such an ordered responsive interface.

[0094] It is worth noting that after being stored at 40°C for 14 days, Examples 1 to 3 still retained 36.4% to 44.4% of the temperature-controlled plasticizing ability, proving that the temperature-responsive dual-network structure constructed in this invention has excellent long-term stability and is not a one-time effect.

[0095] Regarding high-temperature performance, the flexural strength at 1400℃ in all embodiments was 9.0 to 9.5 MPa, significantly better than the 6.0 MPa of Comparative Example 1 and the 7.8 to 8.3 MPa of Comparative Examples 3 to 6; the slag erosion resistance depth was 3.2 to 4.0 mm, also significantly lower than that of the phosphate-bonded system. This indicates that the phosphorus-free aluminum sol-bonded system of the present invention, while imparting intelligent construction characteristics to the material, did not sacrifice its high-temperature service performance, but rather improved it. The P2O5 and SO3 contents in all embodiments were controlled below 0.02 wt%, meeting the purity requirements of high-end special smelting.

[0096] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it.

Claims

1. An aluminum sol-bonded plastic, characterized in that, Including the following parts by weight of raw materials: Corundum aggregate: 35-50 parts; Corundum powder: 25-35 parts; Activated alumina micro powder: 8-15 parts; Aluminum sol: 5-12 parts; Block copolymer: 1.0-4.0 parts; Moisturizer: 0.5-2.0 parts; The block copolymer is a copolymer with an ABA-type triblock structure, wherein the A segment is a polyacrylic acid segment, the B segment is a polypropylene oxide segment, the number average molecular weight is 8000-25000 g / mol, and the phase transition temperature of the B segment is 31-35℃.

2. The aluminum sol-bonded plastic according to claim 1, characterized in that: The phase transition temperature of the B segment is 33-35℃.

3. The aluminum sol-bonded plastic according to claim 1, characterized in that: The number-average molecular weight of the block copolymer is 10,000-20,000 g / mol.

4. The aluminum sol-bonded plastic according to claim 1, characterized in that: The corundum aggregate comprises a continuous gradation consisting of at least two of the following particle sizes: 5-3 mm, 3-1 mm, and 1-0.088 mm.

5. The aluminum sol-bonded plastic according to claim 1, characterized in that: The particle size of the corundum powder is less than 0.088 mm; The median diameter D50 of the activated alumina micro powder is 1.5-4.0 μm; The aluminum sol has a solid content of 20-40% and a pH value of 3.0-5.

0.

6. The aluminum sol-bonded plastic according to claim 5, characterized in that: The pH value of the aluminum sol is 3.8-4.

5.

7. The aluminum sol-bonded plastic according to claim 1, characterized in that: The humectant is one or more of glycerin, sorbitol, and xylitol; the weight ratio of the humectant to the block copolymer is 1:(0.5-4).

8. A method for preparing an aluminum sol-bonded plastic according to any one of claims 1-7, characterized in that, Includes the following steps: (1) Disperse the block copolymer and humectant in the aluminum sol and stir until homogeneous at a temperature at least 2°C lower than the phase transition temperature of the block copolymer and not higher than 30°C to obtain an active binding solution; (2) The active binding liquid is mixed with the corundum aggregate, corundum fine powder and active alumina micro powder in a stirring device at a temperature at least 2°C lower than the phase change temperature of the block copolymer and not higher than 30°C to obtain wet mud. (3) The wet mud is placed in a closed environment and left to stand for 12-24 hours at a temperature at least 2°C lower than the phase change temperature of the block copolymer and not higher than 30°C. (4) After the material is trapped, it is squeezed and packaged to obtain the plastic.

9. The method for preparing aluminum sol-bonded plastic according to claim 8, characterized in that: The temperature in steps (1) to (3) is controlled at 5-28℃.

10. The application of the aluminosilicate bonded plastic as described in any one of claims 1-7 in the repair of the lining of a medium-frequency induction furnace.

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