1. The fireproof magnesium oxide board is characterized by being prepared by mixing the following raw materials in parts by weight: 80-100 parts of magnesium oxide; 20-30 parts of anhydrous magnesium chloride; 10-20 parts of fireproof sepiolite fiber slurry; 20-30 parts of aluminum silicate fiber; 5-10 parts of sawdust; 10-15 parts of fly ash; 8-12 parts of magnesium oxide board crushed powder; 1.5-5 parts of non-woven fabric; 6-8 parts of water, wherein the fireproof sepiolite fiber slurry comprises the following components in parts by weight: 20-50 parts of modified sepiolite wool, 5-10 parts of talcum powder, 10-15 parts of plant rubber powder, 10-20 parts of polypropylene fiber, 1-5 parts of cellulose ether, 1-3 parts of surfactant and 40-150 parts of deionized water, wherein the preparation method of the slurry comprises the following steps:

(1) preparing modified sepiolite wool: acid activation: mixing sepiolite with acid liquor according to the solid-liquid weight ratio of 1 (1-1.5), stirring for 10-12h, wherein the acid liquor contains 1-3% of mixed acid by volume fraction to obtain first sepiolite slurry; wherein the mixed acid is the mixture of hydrochloric acid and phosphoric acid, and the molar ratio of the mixed acid to the phosphoric acid is 1: (0.8-1.2);

(2) alkali neutralization: mixing the first sepiolite slurry after acid activation with ammonia water according to the solid-liquid weight ratio of 1 (1-1.5), and stirring for 10-12h to obtain a second sepiolite slurry, wherein the molar ratio of the mixed acid in the acid solution to the ammonia water is (0.9-1) to 1;

(3) and sequentially adding talcum powder, plant rubber powder, polypropylene fiber, cellulose ether and surfactant into the second sepiolite slurry while stirring to obtain the fireproof sepiolite fiber slurry.

2. The fire-resistant magnesium oxide panel according to claim 1, wherein the surfactant is sodium dodecylbenzene sulfonate, sodium dodecylsulfate, sodium lauryl sulfate, octylphenol polyoxyethylene ether, cetyl trimethyl ammonium bromide, polyvinylpyrrolidone, or sodium lauryl sulfate.

3. The fireproof magnesium oxide board according to claim 1, wherein the plant gum powder is any one or a combination of more of xanthan gum powder, guar gum powder, Rowang seed gum powder, locust bean gum powder and konjac gum powder.

4. The fire resistant magnesium oxide board of claim 1, wherein the cellulose ether is hydroxyethyl cellulose, hydroxypropyl cellulose, methyl hydroxyethyl cellulose, ethyl hydroxyethyl cellulose, methyl hydroxypropyl cellulose, methyl cellulose, or xanthan gum.

5. The fireproof magnesium oxide board according to claim 1, wherein the acid solution contains 2% by volume of mixed acid, and the mixed acid is a mixture of hydrochloric acid and phosphoric acid, and the molar ratio of the mixed acid to the phosphoric acid is 1:1.

6. the fireproof magnesium oxide panel according to claim 1, wherein the talc powder has a mesh size of 400-600 meshes.

7. The fireproof magnesium oxide panel according to claim 1, wherein the stirring speed in step 1 is 500 rpm 300-.

8. A manufacturing process of a fireproof magnesium oxide plate is characterized by being applied to the fireproof magnesium oxide plate of any one of claims 1 to 7, and comprising the following steps of:

(1) putting magnesium oxide, anhydrous magnesium chloride, fireproof sepiolite fiber slurry and magnesium oxide board crushed powder into a stirrer according to the weight part of the magnesium oxide board in the claim 1, stirring, filling gas into the stirrer to form bubbles, and stirring for 15 minutes;

(2) adding the aluminum silicate fiber, the fly ash and the sawdust into a stirrer according to the weight parts of the magnesium oxide board, continuously stirring and mixing, uniformly stirring for 30 minutes to prepare slurry,

(3) then introducing the prepared template into a press, and laying the non-woven fabric;

(4) taking out the slurry obtained in the step (2), adding the slurry into a charging hopper of a press, filling the slurry into template non-woven fabric, pressing to a required size, and demolding after drying for 8-10 hours;

(5) placing the cured plate and the template in a reverse direction, slightly supporting one corner of the mold by hand, dropping the cured plate by hand, and taking off one side of the mold from the corner to lift the mold;

(6) stacking the formed and demoulded plates together, curing in a curing room for 3 days, and then putting the product into a dry room for 10 days;

(7) and cutting four sides of the dried plate according to the specification requirement.

Background

The magnesium oxide board is a novel multifunctional building material, has the light weight, flexibility and reprocessing performance of a wood organic board, has the fire resistance and water resistance of an inorganic board, and is applied to wall bodies, suspended ceilings, floor lining boards and other decoration parts with fire protection requirements. The main components of the existing magnesium oxide board are glass fiber mesh cloth (the main source of board strength), magnesium oxide, magnesium chloride, perlite, filling fiber and modified additive. However, the magnesium oxide board used at present has the problems of moisture absorption and halogen return of the board, embrittlement of the board and the like, influences the quality of the product, has poor fireproof and heat-insulating properties and limits the wide application of the product. The Chinese patent application CN201310232377 tries to adopt an expanded foaming material consisting of melamine, pentaerythritol and ammonium polyphosphate to obtain a certain flame retardant effect, but the flame retardant property is difficult to meet the severe requirement of high-end markets on the flame retardant property, such as the fire resistance limit value is more than or equal to 4 hours, so that the flame retardant property of the expanded foaming material needs to be improved by further adding flame retardant fillers such as sepiolite and the like.

Sepiolite with a theoretical structural formula of Mg₈Si₁₂O₃0(OH)₄(OH₂)₄·8H₂And O, wherein silicon-oxygen tetrahedrons and magnesium-oxygen octahedrons alternate with each other in the structural unit, and have the transition type characteristics of layers and chains. Due to the unique structure, the sepiolite has good adsorbability, rheological property and catalytic property, and the sepiolite mineral fibers are easy to disintegrate into irregular fiber networks in water and other high and medium polar solutions, so that high-viscosity stable suspension can be formed at low concentration. A large amount of Si-OH groups exist on the surface of the sepiolite, and the sepiolite has strong affinity. Sepiolite can separate out 3 types of adsorption active centers: oxygen atoms in silicon-oxygen tetrahedrons; (ii) moisture coordinated to the magnesium ion on the octahedral sideA seed; and the Si-OH ion groups are generated by breaking Si-O-Si bonds on the surface outside the tetrahedron. These Si-OH ionic groups are capable of interacting with molecules adsorbed on the sepiolite surface and have the ability to form covalent bonds with certain organic reagents. The sepiolite has high specific surface area and large porosity; the melting point of the material is 1500-1700 ℃, and the material has good thermal stability. The abundant elements such as magnesium, silicon and the like in the sepiolite are excellent halogen flame retardant elements, so that the sepiolite becomes a potential environment-friendly flame retardant or flame retardant synergist in the flame retardant research, has wide sources, is non-toxic and harmless, and can possibly achieve good flame retardant and smoke suppression effects when being applied to flame retardant. The sepiolite has good thermal stability, can keep the skeleton stable in the combustion process and plays a role in protecting a carbon layer, and the smoke suppression effect of the sepiolite is that the sepiolite has a large specific surface area due to a porous structure, so that the good adsorption function of the sepiolite is determined. Meanwhile, the air heat conductivity coefficient of the pore passage is far smaller than that of the solid, namely, the sepiolite has good heat resistance effect. Therefore, the sepiolite is used as the filler of the fireproof coating or the fireproof plate, which is expected to contribute to the improvement of the fireproof performance of the fireproof coating or the fireproof plate, and the sepiolite is widely used as the fireproof filler in the coating and fireproof plate industry at present.

However, in the field of fire-retardant coatings or fire-retardant panels, which are conventional fire-retardant fillers in the field of coatings or fire-retardant panels, the fillers are added to the coating or fire-retardant panel slurry together with other fillers for dispersion, but the applicant has found that the coating or fire-retardant panel slurry to which a large amount of sepiolite fibers is added has several problems: (1) compared with the flame retardants such as expanded vermiculite, magnesium hydroxide, antimony trioxide and the like, the flame retardant property of the flame retardant is to be further improved; (2) in the process of drying and curing the coating or the fireproof plate, the drying time is too long, and the production efficiency is greatly reduced, because the sepiolite has good water absorbability and water retentivity, the sepiolite after water absorption forms a water blocking barrier to block the diffusion of water from the inside to the outside surface, so that the surface drying of a coating film and the fireproof plate is caused, but the actual interior is not dried, namely the surface drying is fast, but the actual drying time is longer; (3) in the actual production process, the viscosity of the system is rapidly increased at the moment of adding the sepiolite with larger amount, so that the stability of the dispersion system is damaged, the dispersion time is prolonged, the production efficiency is reduced, and the dispersion effect is poor. The fireproof board is taken as an example, because the sepiolite also has the function of a thickening agent, the sepiolite can quickly absorb water and flocculate when entering water, so that the water absorption capacity is large, the viscosity of a slurry dispersion system in the board manufacturing process can be quickly improved, the dispersed slurry can be reunited, the stability of the high molecular micelle is reduced, and sedimentation can be generated if the high molecular micelle is serious.

Disclosure of Invention

The invention provides a fireproof magnesium oxide board which is prepared by mixing the following raw materials in parts by weight: 80-100 parts of magnesium oxide; 20-30 parts of anhydrous magnesium chloride; 10-20 parts of fireproof sepiolite fiber slurry; 20-30 parts of aluminum silicate fiber; 5-10 parts of sawdust; 10-15 parts of fly ash; 8-12 parts of magnesium oxide board crushed powder; 1.5-5 parts of non-woven fabric; 6-8 parts of water, wherein the fireproof sepiolite fiber slurry comprises the following components in parts by weight: 20-50 parts of modified sepiolite wool, 5-10 parts of talcum powder, 10-15 parts of plant rubber powder, 10-20 parts of polypropylene fiber, 1-5 parts of cellulose ether, 1-3 parts of surfactant and 40-150 parts of deionized water, wherein the preparation method of the slurry comprises the following steps:

(1) preparing modified sepiolite wool: acid activation: mixing sepiolite with acid liquor according to the solid-liquid weight ratio of 1 (1-1.5), stirring for 10-12h, wherein the acid liquor contains 1-3% of mixed acid by volume fraction to obtain first sepiolite slurry; wherein the mixed acid is the mixture of hydrochloric acid and phosphoric acid, and the molar ratio of the mixed acid to the phosphoric acid is 1: (0.8-1.2);

(2) alkali neutralization: mixing the first sepiolite slurry after acid activation with ammonia water according to the solid-liquid weight ratio of 1 (1-1.5), and stirring for 10-12h to obtain a second sepiolite slurry, wherein the molar ratio of the mixed acid in the acid solution to the ammonia water is (0.9-1) to 1;

(3) and sequentially adding talcum powder, plant rubber powder, polypropylene fiber, cellulose ether and surfactant into the second sepiolite slurry while stirring to obtain the fireproof sepiolite fiber slurry.

Preferably, the surfactant is sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, octyl phenol polyoxyethylene ether, hexadecyl trimethyl ammonium bromide, polyvinylpyrrolidone or sodium lauryl sulfate.

Preferably, the plant gum powder is any one or combination of more of xanthan gum powder, guar gum powder, Rowang seed gum powder, locust bean gum powder and konjac gum powder.

Preferably, the cellulose ether is hydroxyethyl cellulose, hydroxypropyl cellulose, methylhydroxyethyl cellulose, ethylhydroxyethyl cellulose, methylhydroxypropyl cellulose, methyl cellulose or xanthan gum.

Preferably, the acid solution contains 2% by volume of mixed acid, and the mixed acid is a mixture of hydrochloric acid and phosphoric acid, and the molar ratio of the mixed acid to the phosphoric acid is 1:1.

preferably, the mesh number of the talcum powder is 400-600 meshes.

Preferably, in the step 1, the stirring speed is 300-500 rpm, in the step 2, the stirring speed is 500-800 rpm, and in the step 3, the stirring speed is 800-1200 rpm.

The invention further provides a manufacturing process of the fireproof magnesium oxide plate, which comprises the following steps:

(1) putting the magnesium oxide, the anhydrous magnesium chloride, the fireproof sepiolite fiber slurry and the glass magnesium board crushed powder into a stirrer by weight parts, stirring, filling gas into the stirrer to form bubbles, and stirring for 15 minutes;

(2) adding the aluminum silicate fiber, the fly ash and the sawdust into a stirrer according to the weight parts of the magnesium oxide board, continuously stirring and mixing, uniformly stirring for 30 minutes to prepare slurry,

(3) then introducing the prepared template into a press, and laying the non-woven fabric;

(4) taking out the slurry obtained in the step (2), adding the slurry into a charging hopper of a press, filling the slurry into template non-woven fabric, pressing to a required size, and demolding after drying for 8-10 hours;

(5) placing the cured plate and the template in a reverse direction, slightly supporting one corner of the mold by hand, dropping the cured plate by hand, and taking off one side of the mold from the corner to lift the mold;

(6) stacking the formed and demoulded plates together, curing in a curing room for 3 days, and then putting the product into a dry room for 10 days;

(7) and cutting four sides of the dried plate according to the specification requirement.

After the technical scheme is adopted, the invention at least has the following beneficial effects:

(1) the acid activation has two effects, namely, H & lt + & gt in the acid liquor replaces Mg2 & lt + & gt in a skeleton, and an Si-O skeleton generates Si-OH groups, so that carbonate impurities between sepiolite layers and in pore channels are removed, internal channels of the sepiolite are communicated, micropores are developed into mesopores, the micropore ratio is reduced, the mesopore ratio is increased, the specific surface area of the sepiolite is greatly improved, and more importantly, the water absorption of the sepiolite can be reduced by reducing the active center of Mg2 & lt + & gt, so that the balance of water loss and water retention performance of the sepiolite is realized.

(2) The hydrochloric acid is adopted in the acid solution, so that compared with nitric acid and sulfuric acid, the hydrochloric acid has the function of strong acid, contains halogen chloride, and can improve the overall fire resistance of the sepiolite.

(3) The alkali liquor treatment is to further treat the sepiolite slurry activated by the strong acid, the ammonia water and magnesium ions precipitated by the strong acid activation form stable magnesium hydroxide solid, the magnesium hydroxide generated by the reaction is uniformly dispersed in the pore channel, the pore channel is not blocked, the structural strength and the thermal stability of the sepiolite are improved, and the adverse effects of the magnesium ions in the slurry on the corrosion resistance and the water resistance of the fireproof coating and the fireproof plate are avoided. In addition, the more key effect is that the generated magnesium hydroxide is an excellent flame retardant which gradually decomposes at 40 ℃, absorbs a large amount of heat and releases water, mainly plays the roles of flame retardant, foaming agent and smoke abatement in the fireproof material, cannot decompose into gas compounds to be burned out under flame and high temperature, can play the role of durable combustion with the stability of the magnesium hydroxide, further improves the thermal stability of the sepiolite, and generates excellent flame retardant performance by matching with the special porous structure of the sepiolite.

(4) The ammonium phosphate is a common dehydration and carbonization catalyst in the fire protection field, and generates polyphosphoric acid at high temperature, and the polyphosphoric acid can generate strong esterification reaction with polyhydroxy compounds and dehydrate to initiate an expansion process.

In conclusion, through continuous acidification and alkalization, the specific surface area of the sepiolite is increased, and meanwhile, through the selection of concentration and specific substances, the water absorption performance of the sepiolite is optimized, the curing time of the sepiolite slurry product is improved, and meanwhile, through the generation of magnesium hydroxide and ammonium phosphate, the fireproof performance of the sepiolite slurry is also obviously improved, so that the fireproof performance of the fireproof magnesium oxide plate is improved.

If the dosage of the hydrochloric acid and the ammonia water is too high, the magnesium phosphate blocks a channel, and the dosage is too low, so that the effects of improving the thermal stability and reducing the concentration of magnesium ions cannot be realized. The phosphoric acid solution should be slowly dripped to avoid local enrichment of phosphoric acid in the sepiolite dispersed slurry and generate a large amount of magnesium phosphate to block the channel.

(5) The talcum powder reduces the cost of the slurry and improves the strength of the product, the anti-cracking performance of the product is improved by adding the polypropylene fiber, the hydrophilicity of the polypropylene fiber is improved by adding the surfactant, the water-loss and water-retention balance performance of the slurry is further improved, and the curing and drying performance of the fireproof magnesium oxide plate is finally improved.

Detailed Description

The technical solution of the invention will be described in detail with reference to the specific examples.

Example 1

The embodiment of the invention provides a fireproof sepiolite fiber slurry, which comprises the following components in parts by weight: 30 parts of modified sepiolite wool, 5 parts of talcum powder, 12 parts of plant rubber powder, 15 parts of polypropylene fiber, 3 parts of cellulose ether, 2 parts of surfactant and 80 parts of deionized water, wherein the preparation method comprises the following steps:

(1) preparing modified sepiolite wool: acid activation: mixing sepiolite with acid liquor according to the solid-liquid weight ratio of 1:1.5, stirring for 12h, wherein the acid liquor contains 2% by volume of mixed acid to obtain first sepiolite slurry; wherein the mixed acid is the mixture of hydrochloric acid and phosphoric acid, and the molar ratio of the mixed acid to the phosphoric acid is 1: 1;

(2) alkali neutralization: mixing the first sepiolite slurry after acid activation with ammonia water according to the solid-liquid weight ratio of 1:1.5, and stirring for 12 hours to obtain a second sepiolite slurry, wherein the molar ratio of the mixed acid of the acid solution and the alkali solution to the ammonia water is 1: 1;

(3) and sequentially adding talcum powder, plant rubber powder, polypropylene fiber, cellulose ether and surfactant into the second sepiolite slurry while stirring to obtain the fireproof sepiolite fiber slurry A.

Example 2

On the basis of the example 1, the sepiolite and the acid liquor 1 in the step (1) are changed from the solid-liquid weight ratio of 1:1.5 to the solid-liquid weight ratio of 1:2, and other preparation steps are the same, so that the fireproof sepiolite fiber slurry B is obtained

Example 3

On the basis of the example 1, the hydrochloric acid in the step 1 is replaced by sulfuric acid, and other preparation steps are the same, so that the fireproof sepiolite fiber slurry C is obtained.

Example 4

On the basis of the example 1, ammonia water in the step 2 is replaced by a sodium hydroxide solution, and other preparation steps are the same, so that the fireproof sepiolite fiber pulp D is obtained.

Example 5

On the basis of the example 1, the surfactant is replaced by deionized water, and other preparation steps are the same, so that the fireproof sepiolite fiber slurry E is obtained.

Example 6

The fireproof magnesium oxide board is prepared from the following raw materials: 90kg of magnesium oxide; 25kg of anhydrous magnesium chloride; 15kg of modified fireproof sepiolite fiber slurry; 25kg of aluminum silicate fibers; 8kg of sawdust; 12kg of fly ash; 10 parts of magnesium oxide board pulverized powder; 5kg of non-woven fabric; 8kg of water, and the specific preparation process is as follows:

the method comprises the following steps:

(1) putting magnesium oxide, anhydrous magnesium chloride, modified fireproof sepiolite fiber slurry and glass magnesium board crushed powder into a stirrer according to the weight parts of the magnesium oxide board, stirring, filling gas into the stirrer to form bubbles, and stirring for 15 minutes;

(2) adding the aluminum silicate fiber, the fly ash and the sawdust into a stirrer according to the weight parts of the magnesium oxide board, continuously stirring and mixing, uniformly stirring for 30 minutes to prepare slurry,

(3) then introducing the prepared template into a press, and laying the non-woven fabric;

(4) taking out the slurry obtained in the step (2), adding the slurry into a charging hopper of a press, filling the slurry into template non-woven fabric, pressing to a required size, and demolding after drying for 8-10 hours;

(5) placing the cured plate and the template in a reverse direction, slightly supporting one corner of the mold by hand, dropping the cured plate by hand, and taking off one side of the mold from the corner to lift the mold;

(6) stacking the formed and demoulded plates together, curing in a curing room for 3 days, and then putting the product into a dry room for 10 days;

(7) and cutting four sides of the dried plate according to the specification requirement. Among them, a fireproof magnesium oxide panel A, B, C, D, E was obtained by using the sepiolite fiber slurry A, B, C, D, E prepared in examples 1 to 5.

Testing of fire performance

The test for fire endurance (hours) was carried out according to GB50045-95, and the test piece reached the fire endurance when the following occurs. Loss of stability: the column member is axially deformed at a rate greater than h/100(mm) or at an axial deformation rate greater than 3h/1000 (mm/min). h is the initial fire height of the column member after loading and before the fire resistance test, unit: mm.

TABLE 1 fireproof magnesium oxide sheet Properties

Therefore, the flame retardant performance and the comprehensive curing and drying time (mainly the actual drying time) of the fireproof magnesium oxide board added with the fireproof sepiolite fiber slurry modified by a special process are greatly improved. Meanwhile, in the preparation process of example 6, the tendency that the viscosity of the sepiolite product added into the slurry dispersion system is increased rapidly is obviously reduced through the treatment of the sepiolite and the prefabrication of the slurry, and good stability and dispersion efficiency are maintained.