A fireproof magnesium oxide plate

Abstract

A fireproof magnesium oxide board is prepared by mixing the following raw materials, the raw material names and weight parts are as follows: 80-100 parts of magnesium oxide; 20-30 parts of anhydrous magnesium chloride; 10-20 parts of modified expanded vermiculite foaming agent; 20-30 parts of aluminum silicate fiber; 5-10 parts of sawdust; 10-15 parts of fly ash; 8-12 parts of glass magnesium board crushed powder; 1.5-5 parts of non-woven fabric; 10-20 parts of water; wherein the modified expanded vermiculite is prepared by the following steps: (1) Vermiculite is incompletely expanded and calcined; (2) acrylic acid monomer, sodium hydroxide, acrylamide monomer, initiator potassium persulfate, crosslinking aid pentaerythritol polyglycidyl ether, incompletely expanded vermiculite, and water are taken, stirred evenly and ultrasonically dispersed to obtain a first reaction solution, which is placed in a reactor for reaction to obtain a gel material; (3) the gel material is preliminarily crushed and dried, and then further crushed in a ball mill to obtain a fire-resistant expanded vermiculite with water absorption performance.

Description

Technical Field

[0001] The present invention relates to a plate, in particular to a fireproof magnesium oxide plate. Background Art

[0002] Magnesium oxide board is a new type of multifunctional building material. Because it has the lightness, flexibility and reprocessing performance of wood-based organic boards, and the fire resistance and water resistance of inorganic boards, it is used in the decoration of walls, ceilings, floor linings and other parts with fire protection requirements. The main components of the current magnesium oxide board are glass fiber mesh cloth (the main source of the board's strength), magnesium oxide, magnesium chloride, perlite, filling fiber and modified additives. However, the magnesium oxide boards currently used have problems such as moisture absorption and halogen return of the board, and embrittlement of the board, which affect the quality of the product, and the fireproof and heat-insulating performance is also poor, limiting the wide application of the product. Chinese patent application CN201310232377 attempts to use an expanding foaming material composed of melamine, pentaerythritol and ammonium polyphosphate, and obtains a certain flame retardant effect, but the flame retardant performance is difficult to meet the stringent requirements of the high-end market for flame retardant performance, such as a fire resistance limit value of greater than or equal to 4 hours.

[0003] Vermiculite is a complex hydrous ferromagnesian silicate mineral, a regenerative mineral formed by hydrothermal alteration or weathering of mica-based minerals. Its chemical composition is [(Mg, Fe, Al)₃(Si, Al)₄O₁₁₁₁]·4H₂O, but this composition often varies. It is monoclinic and flaky, with a hardness of 1 to 1.5 and a density of 2400 to 2700 kg / m₃. Thin flakes are flexible. Its most important property is its expansion upon heating, reaching maximum expansion at temperatures between 800 and 1000°C, with expansion ratios of 8 to 15 times, and sometimes as high as 30 times. Expanded vermiculite generally has a density of 80 to 200 kg / m₃, a thermal conductivity of 0.047 to 0.07 W / (m·K), a sound absorption coefficient of 0.50 to 0.63 (at 512 Hz), and a refractoriness of 1300 to 1350°C. Expanded vermiculite also exhibits excellent frost resistance in its dry state. At -20°C, its particle size and composition remain unchanged after 15 freeze-thaw cycles. Furthermore, as an inorganic material, it is resistant to fungal attack, decay, deterioration, and is not susceptible to insects or rodents. These numerous advantages have led to its widespread application. While vermiculite is primarily used in the construction industry, it also has unique applications in other fields. The production process for expanded vermiculite is as follows: After removing impurities from the vermiculite, it is crushed into 1-2 mm particles and screened to remove fines. After drying (preheating), the raw material is placed in a rotary kiln or vertical kiln for expansion heat treatment. The thermal regime of this expansion heat treatment significantly influences the expansion rate of the vermiculite. Generally, the vermiculite is slowly heated to 100°C before being rapidly placed in a furnace preheated to 1000°C for an expansion time of 0.5-1.0 minutes. After the extrusion heat treatment, the vermiculite is annealed and cooled to become expanded vermiculite. The expanded vermiculite coming out of the furnace needs to be screened to remove the unexpanded impurity particles.

[0004] In the prior art, vermiculite has been modified to obtain higher performance, and a series of attempts have been made. For example, CN115304344A discloses a fireproof and heat-insulating filler for steel fire doors. The fireproof and heat-insulating filler for steel fire doors includes component A and component B. Component A includes the following components in parts by weight: 55-65 parts of a lightweight insulation material, 8-14 parts of expandable graphite, 9-13 parts of bentonite, 7-14 parts of anhydrous gypsum, and 9-14 parts of an auxiliary agent; component B is water, the lightweight insulation material is expanded vermiculite, and the auxiliary agent includes 5-6 parts of a polymer water-retaining agent. Another example is Chinese invention patent publication CN100404612A, which discloses a method for preparing a highly water-absorbent composite material of expanded vermiculite / potassium polyacrylate-acrylamide. This method uses expanded vermiculite as a raw material and prepares the highly water-absorbent composite material through a graft copolymerization reaction of potassium acrylate and acrylamide monomers. This method uses expanded vermiculite at room temperature as a raw material for compounding with organic matter, utilizing the expanded vermiculite to improve the network structure and water-absorbent groups of potassium polyacrylate-acrylamide, thereby improving the material's performance and reducing production costs.

[0005] As we all know, expanded vermiculite is used in fireproof materials such as magnesium oxide sheets, primarily due to its heat resistance and hollow structure, which provide excellent fireproofing and heat insulation. The addition of a water-retaining agent takes advantage of the fact that during a fire, the water-retaining agent loses a large amount of water, causing it to volatilize, dissipating heat and lowering the temperature. However, the amount of water-retaining agent used in the material is limited. Excessive use can severely reduce the initial strength of the fireproofing material. Furthermore, during a fire, the volatilization of water creates numerous voids within the material, resulting in a lack of internal strength support, causing a sharp drop in the fireproofing material's strength and making it prone to collapse. As can be seen, the expanded vermiculite in CN115304344A is only mixed with a water-retaining agent, and the amount of water-retaining agent used is limited, which limits the fireproofing performance and strength of the fireproofing material. While CN100404612A prepares a composite water-absorbing material modified with expanded vermiculite and polyacrylate potassium-acrylamide, which greatly improves the water absorption performance of the water-absorbing material, this technology uses the polyacrylate potassium-acrylamide polymer water-absorbing material as the main water-absorbing material, and the expanded vermiculite is merely used as an aggregate to improve its network structure strength and water absorption. The high content of water-retaining material as the main component limits its use in fireproofing materials. As found in actual use, excessive use can lead to a sharp drop in strength and collapse of the fireproofing material. Summary of the Invention

[0006] The invention provides a fireproof magnesium oxide board, which is characterized by being prepared by mixing the following raw materials, the names and weight proportions of the raw materials being as follows: 80-100 parts of magnesium oxide; 20-30 parts of anhydrous magnesium chloride; 10-20 parts of a modified expanded vermiculite foaming agent; 20-30 parts of aluminum silicate fiber; 5-10 parts of sawdust; 10-15 parts of fly ash; 8-12 parts of glass magnesium board crushed powder; 1.5-5 parts of non-woven fabric; and 10-20 parts of water.

[0007] The modified expanded vermiculite is prepared by the following steps:

[0008] (1) Incomplete expansion calcination of vermiculite: take the vermiculite raw material, remove impurities, and put it into a rotary kiln at a temperature of 700-1000℃, heat and expand it for 10-20 seconds, and then obtain incomplete expanded vermiculite with a bulk density of 1000-1200kg / m 3 ;

[0009] (2) taking acrylic acid monomer, sodium hydroxide, acrylamide monomer, initiator potassium persulfate, crosslinking aid pentaerythritol polyglycidyl ether, incompletely expanded vermiculite, and water, stirring uniformly and performing ultrasonic dispersion for 20-40 minutes to obtain a first reaction solution, and placing the solution in a reactor for reaction at a temperature of 80-100° C. for a reaction time of 0.5-2 hours to obtain a gel material; wherein the mass ratio of acrylic acid monomer, acrylamide monomer, and incompletely expanded vermiculite is (2-4): (0.4-0.6): 6;

[0010] (3) The gel material is preliminarily crushed, dried at 150-200° C., and then further pulverized in a ball mill until a fire-resistant expanded vermiculite with a particle size of 0.6-1.0 mm and water absorption performance is obtained.

[0011] The production process of fireproof magnesium oxide plate is characterized by comprising the following steps:

[0012] (1) Magnesium oxide, anhydrous magnesium chloride, a foaming agent, and crushed magnesium plate powder are placed in a blender according to the weight of the magnesium oxide plate, and stirred. At the same time, gas is introduced into the blender to form bubbles, and stirred for 15 minutes;

[0013] (2) Add aluminum silicate fiber, fly ash and sawdust into a blender according to the weight of the magnesium oxide board, continue stirring and mixing, and evenly stir for 30 minutes to make a slurry.

[0014] (3) The prepared template is introduced into the press and the non-woven fabric is laid;

[0015] (4) Take out the slurry in step (2) and add it to the press hopper, then fill the slurry into the template seamless cloth, press it to the required size, and demould it after drying for 8-10 hours;

[0016] (5) Place the cured sheet together with the template in reverse, gently lift one corner of the mold with your hand, and press the cured sheet to fall off. Then, start from this corner to remove one side and lift up the mold;

[0017] (6) Stack the formed and demoulded plates together, cure them in a curing room for 3 days, and then place the products in a dry room for 10 days;

[0018] (7) Then cut the four sides of the dried board according to the specifications.

[0019] Among them, the operating temperature of the rotary kiln is 850-950℃, and the heating expansion time is 12-15 seconds.

[0020] Among them, the heating expansion time is 13 seconds.

[0021] Among them, the bulk density of incompletely expanded vermiculite is 1000-1100kg / m3.

[0022] Wherein, the stirring speed in the reactor in step (2) is 1200-1800 rpm.

[0023] Wherein, in step (2), the mass ratio of acrylic acid monomer to incompletely expanded vermiculite is 1:2.

[0024] Wherein, in step (2), the mass ratio of water to incompletely expanded vermiculite is (15-25):6.

[0025] Through extensive research by R&D personnel in actual production, the present invention allows most of the water-absorbing resin to enter the interlayers of incompletely expanded vermiculite through in-situ polymerization, which can greatly reduce the negative impact of the strong water absorption of the water-absorbing resin on the durability and strength of the refractory material, while greatly improving the refractory property and maintaining the strength of the refractory material.

[0026] The consumption of water is but too much, because vermiculite has water absorbency, a large amount of water can enter the interlayer of expanded vermiculite and have a large amount of reactive monomers to be dispersed therein, when reaction, then in the internal interlayer in-situ polymerization of expanded vermiculite, form macromolecule water-absorbing resin, finally form macromolecule water-absorbing resin and be embedded in expanded vermiculite inside, shell is the fireproof material of expanded vermiculite, certainly, inevitably there will be a small amount of water-absorbing resin on the surface of expanded vermiculite.If the consumption of water is too much, the outside of vermiculite also can have a large amount of water, cause a large amount of acrylic acid to react on the surface of expanded vermiculite, can form a large amount of water-absorbing resin and be exposed to the situation outside of expanded vermiculite, cause fireproof material to descend.Therefore, in the application, in step 2, the mass ratio of water and incomplete expanded vermiculite is (15-25): 6.

[0027] When preparing the first reaction solution, the inventors discovered that conventional dispersion and stirring methods could not achieve the technical objectives of the present invention. Extensive research revealed that ultrasonic dispersion facilitates the rapid incorporation of water and reactive monomers, such as acrylic acid and acrylamide, into the interlayers of the expanded vermiculite. Conventional dispersion, on the other hand, results in the formation of a large amount of water-absorbing resin on the surface of the expanded vermiculite.

[0028] After adopting the above technical solution, the present invention has at least the following beneficial effects:

[0029] (1) By adjusting the amount of water, water-absorbing polymer monomer and expanded vermiculite, and supplemented by ultrasonic dispersion technology, most of the monomers are in situ polymerized in the inner layers of the expanded vermiculite, and finally composite particles with expanded vermiculite as the shell and water-absorbing polymer material as the coating are formed, that is, expanded vermiculite with both water-absorbing and fire-resistant properties.

[0030] (2) In the modified expanded vermiculite, the expanded vermiculite and the water-absorbing polymer have strong water-absorbing properties. The two cooperate with each other, so that the internal interlayer of the expanded vermiculite is filled with the water-absorbing and swollen polyacrylic acid water-absorbing resin. The expanded water-absorbing resin can also increase the interlayer distance of the expanded vermiculite, while at the same time maintaining the strength of the expanded vermiculite as an inorganic mineral filler on the outside. In this way, the water-absorbing properties of the modified expanded vermiculite can be significantly improved, and at the same time, it can also play a reinforcing role on the fireproof material, avoiding the negative impact of the poor strength of the water-absorbing resin on the strength of the fireproof material.

[0031] (3) When the fireproof material containing the modified expanded vermiculite is burned, a large amount of water evaporates, taking away a large amount of heat. Although the water-absorbing resin inside the expanded vermiculite shrinks, it does not significantly affect the strength of the fireproof material. At the same time, further heating causes the incomplete expanded vermiculite to expand further, thus forming a huge heat-insulating gap inside the expanded vermiculite. This shows that the modified expanded vermiculite has a dual fireproofing effect of water volatilization heat absorption and hollow heat insulation, which greatly improves the fireproofing performance of the fireproof material and avoids the problem of insufficient strength of the water-absorbing polymer material and local collapse of the fireproof material caused by water volatilization.

[0032] (4) In actual production, we found that there is also a small amount of water-absorbing resin on the surface of vermiculite, which will shrink at high temperatures and cause material layout defects. We chose the uncommon incompletely expanded vermiculite, which will further expand at high temperatures. This can effectively make up for the space reduced by the shrinkage of the external water-absorbing resin, effectively maintain the strength of the fireproof material at high temperatures, and delay its high-temperature deformation time. DETAILED DESCRIPTION

[0033] The technical solution of the invention is described in detail below with reference to specific embodiments.

[0034] Example 1

[0035] (1) The preparation method of fire-proof expanded vermiculite A comprises the following steps: (1) incomplete expansion and calcination of vermiculite: taking the vermiculite raw material, removing impurities, and putting it into a rotary kiln at a temperature of 850°C, heating and expanding it for 13 seconds, and obtaining incomplete expanded vermiculite after discharging, the density of which is 1050 kg / m 3 ;

[0036] (2) 300 g of acrylic acid monomer, 120 g of sodium hydroxide, 50 g of acrylamide monomer, 1 g of potassium persulfate as an initiator, 0.1 g of pentaerythritol polyglycidyl ether as a crosslinking aid, 600 g of incompletely expanded vermiculite, and 2000 g of water were stirred to obtain a first reaction solution, and reacted in a reactor at a reaction temperature of 85° C. for 1 hour to obtain a gel material;

[0037] (3) The gel material is preliminarily crushed, dried at 170° C., and then further pulverized in a ball mill until a fire-resistant expanded vermiculite with a particle size of 0.6-1.0 mm and water absorption performance is obtained.

[0038] Example 2

[0039] On the basis of Example 1, the incomplete expanded vermiculite was replaced by ordinary expanded vermiculite in the market, and its density was 2500 kg / m 3 , the other preparation steps are the same to obtain modified expanded vermiculite B

[0040] Example 3

[0041] (1) The preparation method of fire-proof expanded vermiculite A comprises the following steps: (1) incomplete expansion and calcination of vermiculite: taking the vermiculite raw material, removing impurities, and putting it into a rotary kiln at a temperature of 850°C, heating and expanding it for 13 seconds, and obtaining incomplete expanded vermiculite after discharging, the density of which is 1050 kg / m 3 ;

[0042] (2) 300 g of acrylic acid monomer, 120 g of sodium hydroxide, 50 g of acrylamide monomer, 1 g of potassium persulfate as an initiator, 0.1 g of pentaerythritol polyglycidyl ether as a crosslinking aid, and 2000 g of water were stirred to obtain a first reaction solution, and reacted in a reactor at a reaction temperature of 85° C. for 1 hour to obtain a gel material;

[0043] (3) The gel material was preliminarily crushed, dried at 170° C., and then further pulverized in a ball mill. 600 g of incompletely expanded vermiculite was added and blended to obtain blended modified expanded vermiculite C.

[0044] Example 4

[0045] On the basis of Example 1, the amount of acrylic acid monomer was adjusted from 300 g to 600 g, and the other preparation steps were the same to obtain modified expanded vermiculite D.

[0046] Example 5

[0047] On the basis of Example 1, the amount of water was adjusted from 2000 g to 3000 g, and the other preparation steps were the same to obtain modified expanded vermiculite D.

[0048] Example 6

[0049] Fireproof magnesium oxide board is prepared from the following raw materials: 90kg of magnesium oxide; 25kg of anhydrous magnesium chloride; 15kg of modified expanded vermiculite foaming agent; 25kg of aluminum silicate fiber; 8kg of sawdust; 12kg of fly ash; 10 parts of glass magnesium board powder; 5kg of non-woven fabric; and 15kg of water. The specific preparation process is as follows:

[0050] (1) Magnesium oxide, anhydrous magnesium chloride, foaming agent, and glass magnesium board powder are placed in a blender according to the weight of the magnesium oxide board and stirred. At the same time, gas is filled into the blender to form bubbles and stirred for 15 minutes;

[0051] (2) Add aluminum silicate fiber, fly ash and sawdust into a blender according to the weight of the magnesium oxide board, continue stirring and mixing, and stir evenly for 30 minutes to make a slurry.

[0052] (3) The prepared template is introduced into the press and the non-woven fabric is laid;

[0053] (4) Take out the slurry in step (2) and add it to the press hopper, then fill the slurry into the template seamless cloth, press it to the required size, and demould it after drying for 8-10 hours;

[0054] (5) Place the cured sheet together with the template in reverse, gently lift one corner of the mold with your hand, and press the cured sheet to fall off. Then, start from this corner to remove one side and lift up the mold;

[0055] (6) Stack the formed and demoulded plates together, cure them in a curing room for 3 days, and then place the products in a dry room for 10 days;

[0056] (7) The dried plate is then cut off from four sides according to the specification requirements. Among them, the fire-resistant magnesium oxide plates A, B, C, D, and E are obtained by using the modified expanded vermiculite A, B, C, D, and E prepared in Examples 1-5.

[0057] Fire performance test

[0058] Fire resistance limit (hours) testing according to GB50045-95 is performed. A specimen reaches its fire resistance limit if any of the following conditions occur: Loss of stability: Axial deformation of the column exceeds h / 100 (mm) or the axial deformation rate exceeds 3h / 1000 (mm / min). h is the initial fire height of the column after loading and before the fire test, in mm.

[0059] Table 1 Test results of magnesium oxide board

[0060] Sample type Modified expanded vermiculite type Fire resistance Magnesium oxide sheet A Modified expanded vermiculite A 5.5h Magnesium oxide sheet B Modified expanded vermiculite B 3.5h Magnesium oxide sheet C Modified expanded vermiculite C 3h Magnesium oxide sheet D Modified expanded vermiculite D 4.5h Magnesium oxide sheet E Modified expanded vermiculite E 4h

[0061] It can be seen that the flame retardant properties of the fireproof magnesium oxide board with the added expanded vermiculite modified by a special process are greatly improved compared with the flame retardant properties of the fireproof magnesium oxide board with the added expanded vermiculite modified by direct blending and other conventional processes.

Claims

1. A fireproof magnesium oxide plate, characterized in that: The following raw materials are mixed, and the names and weight proportions of the raw materials are as follows: 80-100 parts of magnesium oxide; 20-30 parts of anhydrous magnesium chloride; 10-20 parts of modified expanded vermiculite; 20-30 parts of aluminum silicate fiber; 5-10 parts of sawdust; 10-15 parts of fly ash; 8-12 parts of glass magnesium board powder; 1.5-5 parts of non-woven fabric; and 10-20 parts of water. The modified expanded vermiculite is prepared by the following steps: (1) Incomplete expansion calcination of vermiculite: take the vermiculite raw material, remove impurities, and put it into a rotary kiln at a temperature of 700-1000℃, heat and expand it for 10-20 seconds, and then obtain incomplete expanded vermiculite with a bulk density of 1000-1200kg / m 3 ; (2) taking acrylic acid monomer, sodium hydroxide, acrylamide monomer, initiator, crosslinking aid, incompletely expanded vermiculite, and water, stirring uniformly and performing ultrasonic dispersion for 20-40 minutes to obtain a first reaction solution, and placing the solution in a reactor for reaction at a temperature of 80-100° C. for a reaction time of 0.5-2 hours to obtain a gel material; wherein the mass ratio of acrylic acid monomer, acrylamide monomer, and incompletely expanded vermiculite is (2-4): (0.4-0.6): 6; (3) The gel material is preliminarily crushed, dried at 150-200° C., and then further pulverized in a ball mill until a modified expanded vermiculite with a particle size of 0.6-1.0 mm and water absorption performance is obtained.

2. The fireproof magnesium oxide plate according to claim 1, characterized in that: The operating temperature of the rotary kiln is 850-950℃, and the heating expansion time is 12-15 seconds.

3. The fireproof magnesium oxide plate according to claim 1, characterized in that: The heating expansion time is 13 seconds.

4. The fireproof magnesium oxide plate according to claim 1, characterized in that: The bulk density of incompletely expanded vermiculite is 1000-1100kg / m 3 .

5. The fireproof magnesium oxide plate according to claim 1, characterized in that: The stirring speed in the reactor in step (2) is 1200-1800 rpm.

6. The fireproof magnesium oxide plate according to claim 1, characterized in that: In step (2), the mass ratio of acrylic acid monomer to incompletely expanded vermiculite is 1:

2.

7. The fireproof magnesium oxide plate according to claim 1, characterized in that: In step (2), the mass ratio of water to incompletely expanded vermiculite is (15-25):

6.

8. The fireproof magnesium oxide plate according to claim 1, characterized in that: In step (2), the cross-linking auxiliary agent is pentaerythritol polyglycidyl ether.

9. The fireproof magnesium oxide plate according to any one of claims 1 to 8, characterized in that: The fireproof magnesium oxide plate manufacturing process comprises the following steps: (1) Magnesium oxide, anhydrous magnesium chloride, a foaming agent, and crushed glass magnesium board powder are placed in a blender according to the weight proportions of the fireproof magnesium oxide board raw materials described in claims 1-8, and stirred. At the same time, gas is filled into the blender to form bubbles, and stirred for 15 minutes; (2) Add aluminum silicate fiber, fly ash, and sawdust into a blender according to the weight of the fireproof magnesium oxide board raw materials, continue stirring and mixing, and evenly stir for 30 minutes to form a slurry; (3) The prepared template is introduced into the press and the non-woven fabric is laid; (4) Take out the slurry in step (2) and add it to the press hopper, then fill the slurry into the template seamless cloth, press it to the required size, and demould it after drying for 8-10 hours; (5) Place the cured sheet together with the template in reverse, gently lift one corner of the mold with your hand, and press the cured sheet to fall off. Then, start from this corner to remove one side and lift up the mold; (6) Stack the formed and demoulded plates together, cure them in a curing room for 3 days, and then place the products in a dry room for 10 days; (7) Then cut the four sides of the dried board according to the specifications.