Magnesium phosphate cement-based porous sound absorption material and preparation method thereof

Abstract

The invention relates to the technical field of porous materials, and discloses a magnesium phosphate cement-based porous sound absorption material and a preparation method thereof.The trehalose is added into a protein pore-forming agent raw material, and the hydrolysis rate of a protein pore-forming agent in acid magnesium phosphate cement paste can be slowed down in the initial hydration stage of magnesium phosphate cement; therefore, the foam stabilizing effect of the protein pore-forming agent is improved, and the stability of the pore structure in the high-flowability magnesium phosphate cement paste is ensured. Besides, protein in the protein pore-forming agent is gradually hydrolyzed into amino acid or peptide substances in the acid environment of the magnesium phosphate cement paste, and after carboxyl in the amino acid or peptide substances is complexed with part of magnesium ions in the paste, part of the magnesium ions are dispersed in pore channels formed by the protein pore-forming agent; and the release of amino groups gradually forms an alkaline environment around magnesium ions, so that the magnesium ions are induced to generate fibrous magnesium hydroxide, the pore structure is supported, and the problem of pore collapse in the standing and curing process is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of porous materials, in particular to a magnesium phosphate cement-based porous sound-absorbing material and a preparation method thereof. BACKGROUND

[0002] The magnesium phosphate cement is a high-early-strength, fast-setting, high-durability special cementitious material with guanite as the main hydration product. The magnesium phosphate cement porous material prepared by combining the magnesium phosphate cement as the cementitious material and physical foaming can overcome the problems of low production efficiency of traditional granular sound-absorbing materials.

[0003] The magnesium phosphate cement porous material is obtained by adding borax, magnesium oxide and dihydrogen phosphate into a cement paste mixer, uniformly mixing them by dry mixing, adding water, quickly stirring to obtain a high-flow magnesium phosphate cement slurry, then immediately adding a pore-forming agent into the high-flow magnesium phosphate cement slurry, stirring at high speed, pouring into a mold for shaping, and then demolding and curing to a specified age.

[0004] Light-burned magnesium oxide is not suitable as a raw material for the magnesium phosphate cement porous material due to its high activity and fast reaction speed. Therefore, dead-burned magnesium oxide or heavy-burned magnesium oxide is generally used. However, during the preparation of the magnesium phosphate cement porous material, dead-burned magnesium oxide or heavy-burned magnesium oxide has a slow reaction speed, and after adding the pore-forming agent into the high-flow magnesium phosphate cement slurry, it is prone to collapse during the subsequent standing and curing process, resulting in poor pore quality of the magnesium phosphate cement porous material and difficulty in forming a through-hole structure with high sound absorption coefficient. SUMMARY

[0005] To solve the above problems, the present application provides a magnesium phosphate cement-based porous sound-absorbing material and a preparation method thereof, which can slow down the hydrolysis rate of the protein pore-forming agent in the acidic magnesium phosphate cement slurry during the early hydration stage of the magnesium phosphate cement, thereby improving the foam stability of the protein pore-forming agent and ensuring the stability of the pore structure in the high-flow magnesium phosphate cement slurry. In addition, it can induce the formation of fibrous magnesium hydroxide from magnesium ions to support the pore structure, avoid the problem of collapse during the standing and curing process, and further ensure the stability of the through-hole structure in the magnesium phosphate cement porous material.

[0006] To achieve the above technical effects, the technical solution adopted by the present application is as follows: A magnesium phosphate cement-based porous sound-absorbing material, raw materials of the magnesium phosphate cement-based porous sound-absorbing material include, by weight parts, 300-700 parts of magnesium oxide, 100-240 parts of dihydrogen phosphate, 40-100 parts of borax, 10-60 parts of pore-forming agent, and water, the amount of water is configured according to a water-binder ratio of 0.3-2.0; wherein the magnesium oxide is heavy-burned magnesium oxide or dead-burned magnesium oxide, the pore-forming agent is mainly obtained by a high-pressure foaming process of a protein solution, and trehalose accounting for 0.3-5% of the total mass of the pore-forming agent is further added to the protein solution.

[0007] Further, the dihydrogen phosphate includes one or more combinations of potassium dihydrogen phosphate, ammonium dihydrogen phosphate and sodium dihydrogen phosphate.

[0008] Further, the raw materials of the magnesium phosphate cement-based porous sound-absorbing material further include 1-12 parts of pore-adjusting agent, and the pore-adjusting agent is a layered mineral containing aluminum oxide and silicon oxide.

[0009] Further, the effective component of the protein solution is an animal protein foaming agent, and the volume ratio of the animal protein foaming agent to water in the foam preparation process is 1: (5-100), and the prepared foam has a density of 20-100 kg / m 3 .

[0010] Further, the dry density of the magnesium phosphate cement-based porous sound-absorbing material is 200-1000 kg / m 3 .

[0011] To achieve the above technical effects, the application further provides a preparation method of a magnesium phosphate cement-based porous sound-absorbing material for preparing the magnesium phosphate cement-based porous sound-absorbing material, and the preparation method comprises the following steps: According to the amount of each raw material, borax, magnesium oxide and dihydrogen phosphate are mixed, water is added and stirred to obtain a magnesium phosphate cement slurry; The pore-forming agent is added into the magnesium phosphate cement slurry, and after uniform stirring, the magnesium phosphate cement slurry is poured into a mold for molding and curing to a specified age.

[0012] Further, in the preparation of the magnesium phosphate cement slurry, 1-12 parts of pore-adjusting agent are added to the mixture of borax, magnesium oxide and dihydrogen phosphate, and the pore-adjusting agent is a layered mineral containing aluminum oxide and silicon oxide.

[0013] Further, the mold is removed after 24 hours of molding, and the magnesium phosphate cement-based porous sound-absorbing material is cured in an environment of 20℃±2℃ and a relative humidity of 50%±10% to a specified age.

[0014] Compared with the prior art, the application has the following beneficial effects: The present application adds trehalose in the protein pore-forming agent raw material, and the trehalose can form a stable complex by interacting with the protein molecules. After adding the protein pore-forming agent in the high-flow magnesium phosphate cement slurry, the hydrolysis rate of the protein pore-forming agent in the acidic magnesium phosphate cement slurry can be slowed down in the early stage of magnesium phosphate cement hydration, thereby improving the foam stabilizing effect of the protein pore-forming agent and ensuring the stability of the pore structure in the high-flow magnesium phosphate cement slurry. In addition, as the reaction continues, the protein in the protein pore-forming agent is gradually hydrolyzed into amino acids or peptide substances in the acidic environment of the magnesium phosphate cement slurry. The carboxyl groups in the amino acids or peptide substances complex with part of the magnesium ions in the slurry, and then disperse part of the magnesium ions in the pores formed by the protein pore-forming agent. In addition, the release of amino groups gradually forms an alkaline environment around the magnesium ions, thereby inducing the magnesium ions to form fibrous magnesium hydroxide to support the pore structure and avoid the problem of pore collapse during the curing process, thereby further ensuring the stability of the through-pore structure in the magnesium phosphate cement porous material. DETAILED DESCRIPTION

[0015] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below with examples. The illustrative embodiments of the present application and their descriptions are only used to explain the present application, and not as a limitation of the present application.

[0016] Example 1

[0017] A magnesium phosphate cement-based porous sound-absorbing material, the raw materials of the magnesium phosphate cement-based porous sound-absorbing material include, by weight, 300-700 parts of magnesium oxide, 100-240 parts of dihydrogen phosphate, 40-100 parts of borax, 10-60 parts of pore-forming agent, and water, the amount of water is configured according to the water-binder ratio of 0.3-2.0; wherein the magnesium oxide is dead-burned magnesium oxide or dead-burned magnesium oxide, the pore-forming agent is mainly obtained by high-pressure foaming process of a protein solution, and the protein solution further adds trehalose with a total mass of 0.3-5% of the pore-forming agent.

[0018] The preparation method of the magnesium phosphate cement-based porous sound-absorbing material in this example is as follows: according to the amount of each raw material, borax, magnesium oxide, dihydrogen phosphate and water are mixed and stirred to obtain a magnesium phosphate cement slurry; the pore-forming agent is added to the magnesium phosphate cement slurry, and then stirred uniformly and poured into a mold for curing to a specified age.

[0019] In the embodiment, trehalose is added to the protein pore-forming agent raw material. The trehalose can form a stable complex by interacting with protein molecules. After the protein pore-forming agent is added to the high-flow magnesium phosphate cement slurry, the hydrolysis rate of the protein pore-forming agent in the acidic magnesium phosphate cement slurry can be slowed down in the initial hydration stage of the magnesium phosphate cement, thereby improving the foam stabilizing effect of the protein pore-forming agent and ensuring the stability of the pore structure in the high-flow magnesium phosphate cement slurry. In addition, as the reaction continues, the protein in the protein pore-forming agent gradually hydrolyzes into amino acids or peptide substances in the acidic environment of the magnesium phosphate cement slurry. The carboxyl groups in the amino acids or peptide substances complex with part of the magnesium ions in the slurry, and then disperse part of the magnesium ions in the pores formed by the protein pore-forming agent. In addition, the release of amino groups gradually forms an alkaline environment around the magnesium ions, thereby inducing the magnesium ions to generate fibrous magnesium hydroxide to support the pore structure and avoid the problem of pore collapse during the curing process, thereby further ensuring the stability of the through-pore structure in the magnesium phosphate cement porous material.

[0020] The dihydrogen phosphate salt in the embodiment includes one or more combinations of potassium dihydrogen phosphate, ammonium dihydrogen phosphate, and sodium dihydrogen phosphate.

[0021] In the embodiment, 1-12 parts of a pore-adjusting agent, which is a layered mineral containing aluminum oxide and silicon oxide, can be added to the mixture of borax, magnesium oxide, and dihydrogen phosphate salt during the preparation of the magnesium phosphate cement slurry. The layered mineral in the pore-adjusting agent can adsorb magnesium ion complexes, allowing the magnesium hydroxide crystals to grow on the surface of the layered mineral and form a fibrous network structure to support the pore structure and refine the through-pore structure formed by the pore-forming agent, thereby further improving the sound absorption effect of the magnesium phosphate cement-based porous sound absorption material.

[0022] In the embodiment, the effective component of the protein solution is an animal protein foaming agent, and the volume ratio of the animal protein foaming agent to water during the preparation of the foam is 1: (5-100). The density of the prepared foam is 20-100 kg / m 3 .

[0023] Embodiment 2:

[0024] The preparation method of the magnesium phosphate cement-based porous sound absorption material is described in the embodiment, taking the preparation of the magnesium phosphate cement-based porous sound absorption material as an example. The raw materials used in the preparation process are as follows: Magnesium oxide: industrial grade dead-burned magnesium oxide, with a MgO content of 85.7% and a specific surface area of 732 m 2 / kg; Borax: industrial grade, with an effective content of ≥95.0%; KH2PO4: industrial grade, with an effective content of ≥98.0%; Pore adjusting agent: the main component is a layered mineral of alumina and silica, and in this embodiment, montmorillonite is selected as the pore adjusting agent (other types of layered minerals with the main components of alumina and silica such as LDH are also applicable to the present application); Animal protein foaming agent: through high-pressure foaming process, density 35kg / m 3 ; Trehalose: food grade, the main component is a non-reducing disaccharide composed of two glucose molecules, the effective content is ≥98.0%, the molecular formula is C 12 H 22 O 11 ·2H2O.

[0025] The preparation method is as follows: first, the pore forming agent is foamed according to the proportion shown in Table 1, then borax, magnesium oxide, potassium dihydrogen phosphate and pore adjusting agent are added into the cement paste mixer according to the mixing ratio in Table 1, dry mixing for 30s, then adding water according to the water-binder ratio of 0.4, fast stirring for 60s to obtain high-flow magnesium phosphate cement paste, immediately adding the foamed pore forming agent, high-speed stirring for 30s, then pouring into the mold and scraping flat; after 24 hours, demolding, curing in the environment of 20℃±2℃, relative humidity 50%±10% to the specified age.

[0026] Table 1 Mixing ratio of magnesium phosphate cement-based sound-absorbing material (kg / m 3 )

[0027] The prepared magnesium phosphate cement-based porous sound-absorbing material is tested, and the related test items, test procedures and structures are as follows: The 28-day cured sample is dried to dryness in a 50℃ vacuum drying oven, placed in an impedance tube (Beijing Shengwang Acoustics Technology Co., Ltd., SW422), and the full-frequency sound absorption coefficient of the material is tested according to GB / T 18696.2-2002 "Acoustics-Determination of sound absorption coefficient by impedance tube and sound resistance-Part 2: Transfer function method", and the arithmetic mean value of the sound absorption coefficients at 250Hz, 500Hz, 1000Hz and 2000Hz is taken as the noise reduction coefficient (Noise Reduction Coefficient, NRC) according to TB / T 3122-2019, as shown in Table 2.

[0028] Table 2 Sound absorption coefficient statistics table of magnesium phosphate cement-based sound-absorbing material

[0029] The 600-3 sample with good noise reduction effect is cured to 28 days, a thin slice is taken from the center, soaked in anhydrous ethanol to terminate hydration, then placed in a 50℃ vacuum drying oven to dry to absolute dryness, a section thereof is taken and placed in a scanning electron microscope (Tescan, Czech Republic, acceleration voltage 8kV, high vacuum mode) to obtain the micro morphology thereof, which has a large amount of fibrous magnesium hydroxide and a supporting hole structure, avoiding the problem of hole collapse during standing and curing.

[0030] The above is an embodiment of the present application. The above embodiment and the specific parameters in the embodiment are only for the purpose of clearly describing the verification process of the application and are not intended to limit the patent protection scope of the application. The patent protection scope of the application is still subject to its claims. Any equivalent structural changes made in accordance with the description of the application shall also be included in the protection scope of the application.

Claims

1. A magnesium phosphate cement-based porous sound-absorbing material, characterized in that, By weight, the raw materials of the magnesium phosphate cement-based porous sound-absorbing material include 300-700 parts of magnesium oxide, 100-240 parts of dihydrogen phosphate, 40-100 parts of borax, 10-60 parts of pore-forming agent, and water. The amount of water is prepared according to a water-binder ratio of 0.3-2.

0. The magnesium oxide is either calcined magnesium oxide or dead-burned magnesium oxide. The pore-forming agent is mainly obtained by high-pressure foaming of a protein solution. The protein solution also contains 0.3-5% trehalose by weight of the total mass of the pore-forming agent.

2. The magnesium phosphate cement-based porous sound-absorbing material according to claim 1, characterized in that, The dihydrogen phosphate includes one or more combinations of potassium dihydrogen phosphate, ammonium dihydrogen phosphate, and sodium dihydrogen phosphate.

3. The preparation method of the magnesium phosphate cement-based porous sound-absorbing material according to claim 1, characterized in that, The raw materials of the magnesium phosphate cement-based porous sound-absorbing material also include 1-12 parts of a pore-conditioning agent, which is a layered mineral containing alumina and silicon dioxide.

4. The magnesium phosphate cement-based porous sound-absorbing material according to claim 1, characterized in that, The effective component of the protein solution is an animal protein foaming agent. During foam preparation, the volume ratio of the animal protein foaming agent to water is 1:(5-100), and the resulting foam density is 20-100 kg / m³. 3 .

5. The magnesium phosphate cement-based porous sound-absorbing material according to claim 1, characterized in that, The dry density of the magnesium phosphate cement-based porous sound-absorbing material is 200-1000 kg / m³. 3 .

6. A method for preparing a magnesium phosphate cement-based porous sound-absorbing material, used to prepare the magnesium phosphate cement-based porous sound-absorbing material according to any one of claims 1-5, characterized in that, include: According to the proportions of each raw material, borax, magnesium oxide, and dihydrogen phosphate are mixed with water and stirred to obtain magnesium phosphate cement paste; Add a pore-forming agent to the magnesium phosphate cement slurry, stir evenly, pour into a mold, and cure until the specified age.

7. The method for preparing magnesium phosphate cement-based porous sound-absorbing material according to claim 6, characterized in that, In the process of preparing magnesium phosphate cement slurry, 1-12 parts of a pore-conditioning agent are added to the mixture of borax, magnesium oxide and dihydrogen phosphate. The pore-conditioning agent is a layered mineral containing alumina and silicon oxide.

8. The method for preparing magnesium phosphate cement-based porous sound-absorbing material according to claim 6, characterized in that, After molding for 24 hours, the mold is removed and the product is cured in an environment of 20℃±2℃ and relative humidity of 50%±10% until the specified age.

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