Flame-retardant inorganic foaming magnesium oxychloride composite material and preparation method thereof

Abstract

The invention relates to a flame-retardant inorganic foaming magnesium oxychloride composite material and a preparation method thereof. The preparation method comprises the following steps: weighing light calcined magnesia, wood flour, a magnesium chloride aqueous solution, a foaming agent and a cross-linking agent in proportion; uniformly mixing the light calcined magnesia with wood flour, adding a magnesium chloride aqueous solution, a cross-linking agent and a foaming agent, and stirring until uniform slurry is formed, so as to obtain the flame-retardant inorganic foaming magnesium oxychloride composite material. The method has the beneficial effects that the wood flour is adopted as a five-phase crystal growth core and is coordinated with the phytic acid to chelate Mg < 2 + >, and free moisture in a system is absorbed by utilizing the wood flour, so that hydrated crystals in a magnesium oxychloride system are promoted to grow along wood flour fibers, a more compact spatial net structure is formed, and the strength and the water resistance of the system are further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of inorganic foaming materials, and more specifically, it relates to a flame-retardant inorganic foamed magnesium oxychloride composite material and a preparation method thereof. Background Art

[0002] Salt lakes contain rich resources such as potassium chloride and sodium chloride. During the potassium extraction process, a large amount of magnesium chloride by-products are generated. The accumulation of magnesium chloride and the discharge of brine seriously hinder the effective utilization of salt lake resources and the sustainable development ability of salt lakes. The foamed magnesium oxychloride composite material is a porous composite material formed by uniformly mixing a certain proportion of light-burned magnesium oxide and magnesium chloride solution, incorporating pre-prepared foam, and curing for a certain period of time. It has the advantages of low cost, low energy consumption, light weight, high strength, flame retardancy, heat insulation, etc., and is often used in fields such as building materials, thermal insulation materials, and decorations. The source of magnesia resources is rich. The effective utilization of magnesia resources can not only reduce environmental pollution but also be of great significance to environmental development.

[0003] However, traditional inorganic foamed magnesium oxychloride composite materials have problems such as poor water resistance, rehalogenation and efflorescence, and deformation, which limit their industrial applications. Currently, in industry, modification methods such as organic acids, inorganic salts, and mineral powders are often used. However, the modified foamed magnesium oxychloride composite materials have a high density and low compressive strength, which severely limits the application scope of the foamed magnesium oxychloride composite materials.

[0004] In order to improve the strength of the foamed composite material, Chinese Patent CN202410331930.9 discloses a straw composite exterior wall panel and a preparation method thereof. By adding straw plant fibers to fill the foamed composite material, the compressive strength is improved. However, when the foamed composite material doped with straw is cut and soaked in water, the cut surface shows situations such as water absorption, water permeability, mildew, and rot, which affect the mechanical properties and practicality of the composite foamed board. At the same time, Chinese Patent CN202311548605.X discloses a magnesia cement-based steel structure fireproof coating and a preparation method thereof, which effectively improves the fire resistance by using a magnesia cement matrix, functional fillers, flame retardants, inorganic foaming agents, and auxiliary materials. However, the above two foamed composite materials still have problems such as high density and low strength.

[0005] Therefore, it is necessary to provide a new inorganic foamed magnesium oxychloride composite material, its preparation method and application to solve the problems in the prior art. Summary of the Invention

[0006] The purpose of the present invention is to address the deficiencies of the prior art and propose a flame-retardant inorganic foamed magnesium oxychloride composite material and a preparation method thereof.

[0007] In the first aspect, a preparation method of a flame-retardant inorganic foamed magnesium oxychloride composite material is provided, including:

[0008] S1. Weigh light-burned magnesia, wood powder, magnesium chloride aqueous solution, foaming agent and cross-linking agent according to the ratio; the light-burned magnesia is 1300 - 1700 parts by weight, the wood powder is 100 - 140 parts by weight, the magnesium chloride aqueous solution is 1000 - 1400 parts by weight, the foaming agent is 230 - 270 parts by weight, and the cross-linking agent is 6 - 24 parts by weight.

[0009] S2. Mix the light-burned magnesia and the wood powder evenly, add the magnesium chloride aqueous solution, cross-linking agent and foaming agent, and stir until a uniform slurry is formed to obtain a flame-retardant inorganic foamed magnesium oxychloride composite material.

[0010] Preferably, in S1, the light-burned magnesia is obtained by calcining magnesite, and its activity is 60 - 70%.

[0011] Preferably, in S1, the moisture content of the wood powder is 9.5 - 14.5%, and the mesh number is 200 - 350 mesh.

[0012] Preferably, in S1, the foaming agent is a protein foaming agent.

[0013] Preferably, in S1, the cross-linking agent is phytic acid.

[0014] In the second aspect, there is provided a flame-retardant inorganic foamed magnesium oxychloride composite material prepared by the method according to any one of the first aspect, comprising the following components in parts by weight: 1300 - 1700 parts by weight of light-burned magnesia, 100 - 140 parts by weight of wood powder, 1000 - 1400 parts by weight of magnesium chloride aqueous solution, 230 - 270 parts by weight of foaming agent, and 6 - 24 parts by weight of cross-linking agent.

[0015] Preferably, the cross-linking agent is phytic acid; the phosphate groups in the phytic acid form coordination bonds with Mg in the magnesium oxychloride composite material system, and multiple phosphate groups are used to provide multiple binding sites to construct an organic-inorganic hybrid network. 2+ Form coordination bonds and utilize multiple phosphate groups to provide multiple binding sites to construct an organic-inorganic hybrid network.

[0016] Preferably, the wood powder serves as the growth core of the five-phase crystal, chelates with Mg in cooperation with phytic acid 2+ , absorbs the free water in the system by using the wood powder, and promotes the growth of the hydrated crystals in the magnesium oxychloride composite material system along the wood powder fibers to form a dense spatial network structure.

[0017] The beneficial effects of the present invention are as follows:

[0018] 1. The present invention uses wood powder as the growth core of the five-phase crystal, chelates with Mg in cooperation with phytic acid 2+ , absorbs the free water in the system by using the wood powder, thereby promoting the growth of the hydrated crystals in the magnesium oxychloride system along the wood powder fibers to form a denser spatial network structure, and further improving the strength and water resistance of the system.

[0019] 2. The present invention uses the phosphate groups in phytic acid to form coordination bonds with Mg in the magnesium oxychloride composite material system 2+ to construct an organic-inorganic hybrid network by providing multiple binding sites with multiple phosphate groups, and cooperate with the rigid ring structure of phytic acid to improve the compressive strength of the foamed magnesium oxychloride composite material and endow the material with good water resistance.

[0020] 3. The present invention uses wood powder as the skeleton structure and plant fibers as the reinforcing phase, and dissipates the system stress through fiber deformation, extrusion, and fracture, thereby improving the compressive strength of the system.

[0021] 4. The process for preparing the inorganic foamed magnesium oxychloride composite material of the present invention is simple and convenient to operate. The obtained product has excellent performance, high compressive strength, good water resistance, and excellent flame retardancy. The prepared material not only has a low density but also a high strength, which helps to promote the application of magnesium oxychloride composite materials. Description of the Drawings

[0022] Figure 1 It is a schematic diagram of the chelation of phytic acid and wood powder with magnesium ions in the foamed magnesium oxychloride system provided by this application;

[0023] Figure 2 It is a schematic diagram of the comparison of the compressive strength of the foamed magnesium oxychloride composite material provided by this application. Detailed Embodiments

[0024] The following further describes the present invention with reference to the embodiments. The description of the following embodiments is only used to help understand the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several modifications can still be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0025] Embodiment 1:

[0026] To solve the problems of the prior art, Embodiment 1 of this application provides a method for preparing a flame-retardant inorganic foamed magnesium oxychloride composite material, including:

[0027] S1. Weigh light-burned magnesium oxide, wood powder, magnesium chloride aqueous solution, foaming agent, and cross-linking agent according to the ratio; the light-burned magnesium oxide is 1500 kg, the wood powder is 120 kg, the magnesium chloride aqueous solution is 1225 kg, the foaming agent is 250 kg, and the cross-linking agent is 6 kg.

[0028] In S1, the light-burned magnesium oxide is obtained by calcining magnesite at 850 °C, and it is in the form of a white powder with an activity of 60 - 70%. Herein, the activity of magnesium oxide refers to its ability to participate in chemical reactions, and it is commonly expressed in % to represent the proportion of active magnesium oxide in a certain amount of magnesium oxide. The moisture content of the wood powder is 9.5 - 14.5%, and the mesh number is 200 - 350 mesh. The magnesium chloride aqueous solution is made from magnesium chloride with a purity > 98%. The preparation method of the magnesium chloride aqueous solution includes the following steps: Add MgCl₂·6H₂O and water to a beaker and adjust the concentration to 22.5 wt%. The foaming agent is a protein foaming agent. The preparation method of the foaming agent includes the following steps: Using the physical foaming method, at 0.6 - 1.0 MPa, prepare a foam with a uniform density as the foaming agent by mixing the animal protein foaming agent in a ratio of foaming agent : water = 60 : 1000. In addition, the cross-linking agent is phytic acid.

[0029] S2. Mix the light-burned magnesium oxide and the wood powder evenly, add the magnesium chloride aqueous solution, the cross-linking agent and the foaming agent, and stir until a uniform slurry is formed to obtain the flame-retardant inorganic foamed magnesium oxychloride composite material.

[0030] The inorganic foamed magnesium oxychloride composite material of the present invention has high strength and good water resistance. The complexation and coordination of phosphate groups in the system promote the formation of an organic-inorganic hybrid structure, increasing the water-resistant crystal structure in the system and improving the quality stability of the composite product. The strengthening mechanism of the present invention is as Figure 1 shown.

[0031] Example 2:

[0032] Based on Example 1, Example 2 of the present application provides another preparation method of the flame-retardant inorganic foamed magnesium oxychloride composite material, including:

[0033] S1. Weigh the light-burned magnesium oxide, wood powder, magnesium chloride aqueous solution, foaming agent and cross-linking agent according to the ratio; the light-burned magnesium oxide is 1500 kg, the wood powder is 120 kg, the magnesium chloride aqueous solution is 1225 kg, the foaming agent is 250 kg, and the cross-linking agent is 12 kg.

[0034] S2. Mix the light-burned magnesium oxide and the wood powder evenly, add the magnesium chloride aqueous solution, the cross-linking agent and the foaming agent, and stir until a uniform slurry is formed to obtain the flame-retardant inorganic foamed magnesium oxychloride composite material.

[0035] Example 3:

[0036] Based on Example 1, Example 3 of the present application provides another preparation method of the flame-retardant inorganic foamed magnesium oxychloride composite material, including:

[0037] S1. Weigh light-burned magnesium oxide, wood powder, magnesium chloride aqueous solution, foaming agent and cross-linking agent according to the ratio; the light-burned magnesium oxide is 1500 kg, the wood powder is 120 kg, the magnesium chloride aqueous solution is 1225 kg, the foaming agent is 250 kg, and the cross-linking agent is 18 kg.

[0038] S2. Mix the light-burned magnesium oxide and wood powder evenly, add the magnesium chloride aqueous solution, cross-linking agent and foaming agent, and stir until a uniform slurry is formed to obtain a flame-retardant inorganic foamed magnesium oxychloride composite material.

[0039] Example 4:

[0040] On the basis of Example 1, Example 4 of this application provides another preparation method of a flame-retardant inorganic foamed magnesium oxychloride composite material, including:

[0041] S1. Weigh light-burned magnesium oxide, wood powder, magnesium chloride aqueous solution, foaming agent and cross-linking agent according to the ratio; the light-burned magnesium oxide is 1500 kg, the wood powder is 120 kg, the magnesium chloride aqueous solution is 1225 kg, the foaming agent is 250 kg, and the cross-linking agent is 24 kg.

[0042] S2. Mix the light-burned magnesium oxide and wood powder evenly, add the magnesium chloride aqueous solution, cross-linking agent and foaming agent, and stir until a uniform slurry is formed to obtain a flame-retardant inorganic foamed magnesium oxychloride composite material.

[0043] Example 5:

[0044] On the basis of Example 1, Example 5 of this application provides another preparation method of a flame-retardant inorganic foamed magnesium oxychloride composite material, including:

[0045] S1. Weigh light-burned magnesium oxide, wood powder, magnesium chloride aqueous solution, foaming agent and cross-linking agent according to the ratio; the light-burned magnesium oxide is 1300 kg, the wood powder is 100 kg, the magnesium chloride aqueous solution is 1225 kg, the foaming agent is 250 kg, and the cross-linking agent is 12 kg.

[0046] S2. Mix the light-burned magnesium oxide and wood powder evenly, add the magnesium chloride aqueous solution, cross-linking agent and foaming agent, and stir until a uniform slurry is formed to obtain a flame-retardant inorganic foamed magnesium oxychloride composite material.

[0047] Example 6:

[0048] On the basis of Example 1, Example 6 of this application provides another preparation method of a flame-retardant inorganic foamed magnesium oxychloride composite material, including:

[0049] S1. Weigh light-burned magnesium oxide, wood powder, magnesium chloride aqueous solution, foaming agent and cross-linking agent according to the ratio; the light-burned magnesium oxide is 1700 kg, the wood powder is 140 kg, the magnesium chloride aqueous solution is 1225 kg, the foaming agent is 250 kg, and the cross-linking agent is 12 kg.

[0050] S2. Mix the light-burned magnesium oxide and the wood powder evenly, add the magnesium chloride aqueous solution, cross-linking agent and foaming agent, and stir until a uniform slurry is formed to obtain a flame-retardant inorganic foamed magnesium oxychloride composite material.

[0051] Example 7:

[0052] On the basis of Example 1, Example 7 of the present application provides another preparation method of a flame-retardant inorganic foamed magnesium oxychloride composite material, including:

[0053] S1. Weigh light-burned magnesium oxide, wood powder, magnesium chloride aqueous solution, foaming agent and cross-linking agent according to the ratio; the light-burned magnesium oxide is 1500 kg, the wood powder is 120 kg, the magnesium chloride aqueous solution is 1000 kg, the foaming agent is 230 kg, and the cross-linking agent is 6 kg.

[0054] S2. Mix the light-burned magnesium oxide and the wood powder evenly, add the magnesium chloride aqueous solution, cross-linking agent and foaming agent, and stir until a uniform slurry is formed to obtain a flame-retardant inorganic foamed magnesium oxychloride composite material.

[0055] Example 8:

[0056] On the basis of Example 1, Example 8 of the present application provides another preparation method of a flame-retardant inorganic foamed magnesium oxychloride composite material, including:

[0057] S1. Weigh light-burned magnesium oxide, wood powder, magnesium chloride aqueous solution, foaming agent and cross-linking agent according to the ratio; the light-burned magnesium oxide is 1500 kg, the wood powder is 120 kg, the magnesium chloride aqueous solution is 1400 kg, the foaming agent is 270 kg, and the cross-linking agent is 6 kg.

[0058] S2. Mix the light-burned magnesium oxide and the wood powder evenly, add the magnesium chloride aqueous solution, cross-linking agent and foaming agent, and stir until a uniform slurry is formed to obtain a flame-retardant inorganic foamed magnesium oxychloride composite material.

[0059] Control Example 1:

[0060] On the basis of Example 2, Control Example 1 provides a preparation method of a flame-retardant inorganic foamed magnesium oxychloride composite material, including:

[0061] S1. Weigh light-burned magnesium oxide, magnesium chloride aqueous solution, foaming agent according to the ratio; the light-burned magnesium oxide is 1500 kg, the magnesium chloride aqueous solution is 1225 kg, and the foaming agent is 250 kg.

[0062] S2. Mix the light-burned magnesium oxide and wood powder evenly, add the magnesium chloride aqueous solution, crosslinking agent and foaming agent, and stir until a uniform slurry is formed to obtain the flame-retardant inorganic foamed magnesium oxychloride composite material.

[0063] Comparative Example 2:

[0064] Based on Example 2, Comparative Example 2 provides a method for preparing a flame-retardant inorganic foamed magnesium oxychloride composite material, including:

[0065] S1. Weigh the light-burned magnesium oxide, magnesium chloride aqueous solution, foaming agent and crosslinking agent according to the ratio; the light-burned magnesium oxide is 1500 kg, the magnesium chloride aqueous solution is 1225 kg, the foaming agent is 250 kg, and the crosslinking agent is 12 kg.

[0066] S2. Mix the light-burned magnesium oxide and wood powder evenly, add the magnesium chloride aqueous solution, crosslinking agent and foaming agent, and stir until a uniform slurry is formed to obtain the flame-retardant inorganic foamed magnesium oxychloride composite material.

[0067] Comparative Example 3:

[0068] Based on Example 2, Comparative Example 3 provides a method for preparing a flame-retardant inorganic foamed magnesium oxychloride composite material, including:

[0069] S1. Weigh the light-burned magnesium oxide, wood powder, magnesium chloride aqueous solution, and foaming agent according to the ratio; the light-burned magnesium oxide is 1500 kg, the wood powder is 120 kg, the magnesium chloride aqueous solution is 1225 kg, and the foaming agent is 250 kg.

[0070] S2. Mix the light-burned magnesium oxide and wood powder evenly, add the magnesium chloride aqueous solution, crosslinking agent and foaming agent, and stir until a uniform slurry is formed to obtain the flame-retardant inorganic foamed magnesium oxychloride composite material.

[0071] In addition, the present application also prepares foamed magnesium oxychloride composite material specimens using the formulations of Examples 1-6 and Comparative Examples 1-3 of the present invention:

[0072] Put the prepared foamed magnesium oxychloride composite material into a mold of 30mm * 30mm * 30mm, demold it after placing it in a normal temperature environment for 24 h, and then use it for testing after normal temperature curing for 3 days. The prepared specimens are tested according to the following detection methods.

[0073] Compressive strength test: Refer to the test method of GBT 5486-2008 "Test Methods for Inorganic Rigid Thermal Insulation Products" to test the compressive strength of the foamed magnesium oxychloride composite material. Use a universal testing machine to compress and damage the FMOC. Place the FMOC on the bearing plate so that the compressed surface of the FMOC contacts the bearing plate, and apply a load to the specimen at a speed of (10±1) mm / min until the specimen is damaged. Record the failure load P (N), and calculate the compressive strength σ = P / S (MPa). The test results are shown in Figure 2 。

[0074] Specific strength test: Measure the size of the prepared specimen, calculate the density of the prepared specimen, and calculate the specific strength of different specimens using the formula (specific strength = p / ρ), where ρ represents density and p represents compressive strength.

[0075] Softening coefficient test: Refer to the test method of GB-T 15231-2008 "Test Methods for Properties of Glass Fiber Reinforced Cement" to test the softening coefficient of the foamed magnesium oxychloride composite material. Immerse the sample in water for 24h, then test the compressive strength of the sample before and after immersion in water, and calculate the softening coefficient of the composite material by Rf = σ1 / σ0. Among them, σ1 represents the compressive strength of the specimen after being immersed in water for 24 hours, and σ0 represents the compressive strength of the specimen without immersion in water.

[0076] Water absorption test: Refer to the test method of GB-T 15231-2008 "Test Methods for Properties of Glass Fiber Reinforced Cement" to test the 24h water absorption of the foamed magnesium oxychloride composite material. Immerse the specimen in water for 24h, measure the mass of the sample before and after immersion in water, and calculate the water absorption of the composite material according to Wa = W1 / W2. Among them, W1 represents the mass of the composite material after being immersed in water for 24h, and W2 represents the mass of the composite material without immersion in water.

[0077] Flame retardancy test: Use a cartridge spray gun to make the foamed magnesium oxychloride composite material into a cube of 100mm×100mm×20mm, burn the center of the cube, and the distance from the fire outlet to the surface of the foamed board is 50mm. Observe and record the burning time when cracks appear on the surface.

[0078] The test results are shown in Table 1 and Figure 2 。

[0079] Table 1

[0080]

[0081] Compared with Example 2, Control Example 1 has no wood powder and cross-linking agent. Compared with Example 2, Control Example 2 has no wood powder. Compared with Example 2, Control Example 3 has no cross-linking agent.

[0082] The above test results show that the inorganic foamed magnesium oxychloride composite material prepared by the present invention has high compressive strength, good water resistance, high flame retardancy, and high product quality stability.

Claims

1. A method for preparing a flame retardant inorganic foamed magnesium oxychloride composite material, characterized in that: include: S1. Weigh light-burned magnesium oxide, wood powder, magnesium chloride aqueous solution, foaming agent and cross-linking agent according to the proportion; the light-burned magnesium oxide is 1300-1700 parts by weight, the wood powder is 100-140 parts by weight, the magnesium chloride aqueous solution is 1000-1400 parts by weight, the foaming agent is 230-270 parts by weight, and the cross-linking agent is 6-24 parts by weight; S2. Evenly mix the light-burned magnesium oxide and wood powder, add magnesium chloride aqueous solution, cross-linking agent and foaming agent, and stir until a uniform slurry is formed to obtain a flame-retardant inorganic foamed magnesium oxychloride composite material.

2. The method for preparing the flame retardant inorganic foamed magnesium oxychloride composite material according to claim 1, characterized in that: In S1, the light-burned magnesium oxide is prepared by calcining magnesite and has an activity of 60-70%.

3. The method for preparing the flame retardant inorganic foamed magnesium oxychloride composite material according to claim 1, characterized in that: In S1, the moisture content of the wood flour is 9.5-14.5%, and the mesh size is 200-350 meshes.

4. The method for preparing the flame retardant inorganic foamed magnesium oxychloride composite material according to claim 1, characterized in that: In S1, the foaming agent is a protein foaming agent.

5. The method for preparing the flame retardant inorganic foamed magnesium oxychloride composite material according to claim 1, characterized in that: In S1, the cross-linking agent is phytic acid.

6. A flame retardant inorganic foamed magnesium oxychloride composite material prepared by the method according to any one of claims 1 to 5, characterized in that: The invention comprises the following components in parts by weight: 1300-1700 parts by weight of light-burned magnesium oxide, 100-140 parts by weight of wood powder, 1000-1400 parts by weight of magnesium chloride aqueous solution, 230-270 parts by weight of foaming agent and 6-24 parts by weight of cross-linking agent.

7. The flame retardant inorganic foamed magnesium oxychloride composite material according to claim 6, characterized in that: The cross-linking agent is phytic acid; the phosphate group in the phytic acid and the Mg in the magnesium oxychloride composite material system 2+ Form coordination bonds, and utilize multiple phosphate groups to provide multiple binding sites to construct an organic-inorganic hybrid network.

8. The flame retardant inorganic foamed magnesium oxychloride composite material according to claim 7, characterized in that: The wood powder acts as the core of five-phase crystal growth and cooperates with phytic acid to chelate Mg 2+ The wood powder is used to absorb free moisture in the system, promoting the growth of hydrated crystals in the magnesium oxychloride composite material system along the wood powder fibers to form a dense spatial network structure.

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