CN110436499B - Method for regulating and controlling oil absorption value of superfine aluminum hydroxide - Google Patents
Method for regulating and controlling oil absorption value of superfine aluminum hydroxide Download PDFInfo
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- CN110436499B CN110436499B CN201910781055.3A CN201910781055A CN110436499B CN 110436499 B CN110436499 B CN 110436499B CN 201910781055 A CN201910781055 A CN 201910781055A CN 110436499 B CN110436499 B CN 110436499B
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F7/00—Compounds of aluminium
- C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
- C01F7/04—Preparation of alkali metal aluminates; Aluminium oxide or hydroxide therefrom
- C01F7/14—Aluminium oxide or hydroxide from alkali metal aluminates
- C01F7/141—Aluminium oxide or hydroxide from alkali metal aluminates from aqueous aluminate solutions by neutralisation with an acidic agent
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F7/00—Compounds of aluminium
- C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
- C01F7/34—Preparation of aluminium hydroxide by precipitation from solutions containing aluminium salts
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F7/00—Compounds of aluminium
- C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
- C01F7/34—Preparation of aluminium hydroxide by precipitation from solutions containing aluminium salts
- C01F7/36—Preparation of aluminium hydroxide by precipitation from solutions containing aluminium salts from organic aluminium salts
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/19—Oil-absorption capacity, e.g. DBP values
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Abstract
The invention discloses a method for regulating and controlling the oil absorption value of superfine aluminum hydroxide, which comprises the steps of preparing aluminum hydroxide by using sodium metaaluminate, sulfuric acid, stearic acid and aluminum sulfate as raw materials, dropwise adding a mixed solution of the sulfuric acid, the stearic acid and the aluminum sulfate into a sodium metaaluminate solution to synthesize the superfine aluminum hydroxide, and regulating and controlling the oil absorption value of a product by regulating the mixing ratio of the stearic acid and the aluminum sulfate. The oil absorption value of the aluminum hydroxide product prepared by the invention is controllable within the range of 20-80%, and the requirements of various application fields are met.
Description
Technical Field
The invention mainly relates to the field of inorganic flame retardants, and mainly relates to a method for regulating and controlling an oil absorption value of superfine aluminum hydroxide.
Background
Throughout the world flame retardant market, the halogen flame retardant is the dominant fire retardant in the fire retardant market, but the demand of the halogen flame retardant is continuously reduced along with the requirement of environmental protection, and the halogen-free low-toxicity fire retardant is used as the substitute. The aluminum hydroxide is taken as a typical halogen-free flame retardant, the consumption accounts for more than 80 percent of the global consumption of the inorganic flame retardant, the aluminum hydroxide has the three functions of flame retardance, smoke abatement and filling, does not produce secondary pollution in the combustion process, can produce synergistic effect with various substances, is nonvolatile, nontoxic, small in corrosivity and low in price, is praised as a pollution-free flame retardant at home and abroad, and is widely applied. Aluminum hydroxide (aluminum hydroxide, chemical formula Al (OH))3The water loss begins to change into Al above 200 DEG C2O3Amphoteric hydroxides. The aluminum hydroxide products are various in types, most of the aluminum hydroxide products have high oil absorption values, and observation of an electron microscope image of the seed-separating aluminum hydroxide shows that the seed-separating materials have long reaction time, perfect crystals and large original crystal grains compared with the carbon-separating materials. The aluminum hydroxide produced by combining carbon component and seed component with lower cost has high oil absorption value of aluminum hydroxide powder due to lower crystallinity, easy agglomeration of particles and irregular appearance. Aluminum hydroxide is the most widely used and widely used inorganic flame retardant additive in the world, not only has the flame retardant characteristic, but also has the functions of preventing fuming, generating no drippings and toxic gases,The combustion has the advantages of no secondary pollution, good filling effect, lower cost and the like, and the usage amount is increased year by year, so that the appearance of the superfine low oil absorption value aluminum hydroxide conforms to the market development trend.
At present, the production process of the superfine aluminum hydroxide mainly comprises two types: one is that common aluminum hydroxide is ground to 2-5.0 μm and directly used as superfine aluminum hydroxide; the other process is a seed crystal seed decomposition process, wherein the seed is prepared by an acid-base neutralization method, the prepared gel-like aluminum hydroxide is used as a seed crystal and is directly dissolved in the sodium aluminate solution, the supersaturation degree of the solution is improved for seed crystal decomposition, and the decomposed superfine aluminum hydroxide is seriously agglomerated. Although the application performance of the superfine aluminum hydroxide prepared by the decomposition process is obviously higher than that of the superfine aluminum hydroxide prepared by the grinding process, the oil absorption value is still very high, and is generally 50-80%.
The superfine aluminum hydroxide is mainly added into a high polymer material to improve the flame retardant property of the base material, and the two materials are mixed and injection molded in a high-temperature hot melting state. If the oil absorption value of the aluminum hydroxide is too high, the mixing viscosity of the two materials is high, and the extrusion molding of the composite material is difficult. Therefore, the market generally demands products with low oil absorption values, and a small number of special fields still demand products with high oil absorption values. Therefore, it is necessary to develop a method for controlling the oil absorption value of ultra-fine aluminum hydroxide to obtain ultra-fine aluminum hydroxide with different oil absorption values.
Disclosure of Invention
Aiming at a series of problems of the oil absorption value control technology in the existing aluminum hydroxide preparation process, the invention synthesizes the superfine aluminum hydroxide by taking sodium metaaluminate, sulfuric acid, stearic acid and aluminum sulfate as raw materials, and achieves the aim of accurately regulating and controlling the oil absorption value of the product through the combined action of a plurality of process parameters in the synthesis process. The technical method mainly comprises the following steps: the aluminum stearate structure generated by the reaction system is controlled by regulating the mixing ratio and the temperature of stearic acid and aluminum sulfate, the aluminum stearate structure comprises aluminum monostearate, aluminum distearate and aluminum tristearate, and because different aluminum stearates carry different carbonyl numbers, the aluminum stearate structure can inhibit different agglomeration degrees of aluminum hydroxide crystal particles, thereby playing a role in regulating the oil absorption value of aluminum hydroxide.
In order to achieve the purpose, the application is realized by the following specific technical scheme:
a method for regulating and controlling the oil absorption value of superfine aluminum hydroxide is characterized in that the superfine aluminum hydroxide is prepared by taking sodium metaaluminate, sulfuric acid, stearic acid and aluminum sulfate as raw materials, and the oil absorption value of the superfine aluminum hydroxide is regulated and controlled by regulating and controlling the mixing ratio of the stearic acid and the aluminum sulfate.
The method for regulating and controlling the oil absorption value of the superfine aluminum hydroxide comprises the following specific operations:
1) putting the sodium metaaluminate solution into a reaction device, starting stirring, and heating to 70-80 ℃ for later use;
2) uniformly mixing a sulfuric acid aqueous solution, stearic acid and aluminum sulfate for later use;
3) dropwise adding the mixed solution prepared in the step 2) into the sodium metaaluminate solution prepared in the step 1) for 4-10h, controlling the temperature at 70-80 ℃ after dropwise adding, carrying out heat preservation reaction for 2h, filtering and separating reaction liquid, leaching filter cakes with hot water, and drying the filter cakes to obtain the superfine aluminum hydroxide with the specific oil absorption value.
The concentration of the sulfuric acid aqueous solution is 20-60%;
the addition amount of the stearic acid is 0.5-5% of the mass of the sodium metaaluminate solution;
the addition amount of the aluminum sulfate is 0.3 to 2.5 percent of the mass of the sodium metaaluminate solution;
the equivalent ratio of the sodium metaaluminate to the sulfuric acid is 1: 0.98-1: 1.02;
drying the filter cake in the step 3), specifically drying at 150 ℃ for 4 h;
the oil absorption value of the superfine aluminum hydroxide product prepared by the method is 20-80%.
The method has the following specific action process: (1) sodium metaaluminate and sulfuric acid are main raw materials for synthesizing aluminum hydroxide, and the sodium metaaluminate solution contains NaAlO2、NaOH、H2And O. Sulfuric acid is dropped into sodium metaaluminate to generate acid-base neutralization reaction, so that the sodium aluminate is promoted to be decomposed into aluminum hydroxide, and the process is a synthesis process of superfine aluminum hydroxide. (2) Stearic acid and aluminum sulfate are simultaneously dropped intoIn the sodium metaaluminate solution, aluminum stearate is generated in an alkaline environment, and one of aluminum monostearate, aluminum distearate and aluminum tristearate tends to be generated according to the molar ratio of stearic acid to aluminum sulfate. (3) Two above-mentioned reactions go on simultaneously, and aluminium hydroxide crystal nucleus and aluminium stearate produce simultaneously, and two kinds of materials are complexed through the aluminium atom for aluminium hydroxide crystal nucleus surface has the alkyl chain, has increased the spatial distance between the crystal nucleus, plays the effect that prevents the crystal nucleus and reunite, and aluminium hydroxide crystal nucleus continues the crystallization growth to aluminium hydroxide product, thereby obtains the aluminium hydroxide product of different reunion degrees, has realized the oil absorption value regulation and control target to superfine aluminium hydroxide promptly.
The invention has the beneficial effects that:
in order to solve the problem of crystal agglomeration in the synthesis process, the invention innovatively adopts a titration method to enhance the agglomeration prevention control of the aluminum hydroxide crystals by adjusting the using amount and the proportion of stearic acid and aluminum sulfate in a titration solution. By adjusting the proportion of stearic acid and aluminum sulfate, different aluminum stearates (aluminum monostearate, aluminum distearate and aluminum tristearate) are generated, the number of alkyl chains carried by the aluminum stearates is different, and the aluminum atoms on the aluminum stearate and the surface of aluminum hydroxide are subjected to ionic bonding, so that hydrophobic alkyl chains are grafted on the surface of aluminum hydroxide particles, the more the number of the alkyl chains is, the lower the agglomeration degree of the generated product is, and the lower the oil absorption value is. The regulation and control process of the invention occurs in the synthesis process of the superfine aluminum hydroxide, the addition amount is small, the operation is simple and efficient, no organic solvent is used, and the invention has essential innovation.
Detailed Description
In order to better understand the technical solution of the present invention, the following further description of the novel method of the present invention is made with reference to specific examples, but it should not be understood that the scope of the subject matter of the present invention is limited to the following examples. All the technologies realized based on the above contents of the present invention belong to the scope of the present invention.
Example 1
300.0g of sodium metaaluminate solution (1.00mol) is put into a reaction bottle, the temperature is raised to 75 ℃, stirring is started, 257g of 40 percent sulfuric acid aqueous solution (1.02mol), 15g of stearic acid and 2.5g of aluminum sulfate are uniformly mixed, after the temperature is reached, the mixture is dripped into the reaction bottle within 10h, heat preservation is continuously carried out for 2h, reaction liquid is filtered and separated, 390g of hot water is used for leaching a filter cake, and the filter cake is dried for 4h at 150 ℃ to obtain the product of the invention, wherein the oil absorption value is 20.2%.
Example 2
300.0g of sodium metaaluminate solution (1.00mol) is put into a reaction bottle, the temperature is raised to 75 ℃, stirring is started, 240.1g of 60 percent sulfuric acid aqueous solution (0.98mol), 1.5g of stearic acid and 1.2g of aluminum sulfate are uniformly mixed, the mixture is dripped into the reaction bottle within 4 hours after the temperature is reached, heat preservation is continued for 2 hours, reaction liquid is filtered and separated, 390g of hot water is used for leaching a filter cake, and the filter cake is dried for 4 hours at 150 ℃ to obtain the product of the invention, wherein the oil absorption value of the product is 80.5 percent.
Example 3
300.0g of sodium metaaluminate solution (1.00mol) is put into a reaction bottle, the temperature is raised to 75 ℃, stirring is started, 247.5g of 40 percent sulfuric acid aqueous solution (1.01mol), 10g of stearic acid and 3.0g of aluminum sulfate are uniformly mixed, after the temperature is reached, the mixture is dripped into the reaction bottle within 8 hours, heat preservation is continuously carried out for 2 hours, reaction liquid is filtered and separated, 390g of hot water is used for leaching a filter cake, and the filter cake is dried for 4 hours at 150 ℃ to obtain the product of the invention, wherein the oil absorption value of the product is 39.2 percent.
Example 4
300.0g of sodium metaaluminate solution (1.00mol) is put into a reaction bottle, the temperature is raised to 75 ℃, stirring is started, 245g of 40 percent sulfuric acid aqueous solution (1.00mol), 7.0g of stearic acid and 3.0g of aluminum sulfate are uniformly mixed, the mixture is dripped into the reaction bottle within 8h after the temperature is reached, heat preservation is continuously carried out for 2h, reaction liquid is filtered and separated, 390g of hot water is used for leaching a filter cake, and the filter cake is dried for 4h at 150 ℃ to obtain the product of the invention, wherein the oil absorption value of the product is 43.7 percent.
Example 5
300.0g of sodium metaaluminate solution (1.00mol) is put into a reaction bottle, the temperature is raised to 75 ℃, stirring is started, 245g of 50 percent sulfuric acid aqueous solution (1.00mol), 3.5g of stearic acid and 2.8g of aluminum sulfate are uniformly mixed, the mixture is dripped into the reaction bottle within 6h after the temperature is reached, heat preservation is continuously carried out for 2h, reaction liquid is filtered and separated, 390g of hot water is used for leaching a filter cake, and the filter cake is dried for 4h at 150 ℃ to obtain the product of the invention, wherein the oil absorption value of the product is 63.7 percent.
Claims (7)
1. A method for regulating and controlling the oil absorption value of superfine aluminum hydroxide is characterized in that the superfine aluminum hydroxide is prepared by taking sodium metaaluminate, sulfuric acid, stearic acid and aluminum sulfate as raw materials, and the regulation and control of the oil absorption value of the superfine aluminum hydroxide are realized by regulating and controlling the mixing ratio of the stearic acid and the aluminum sulfate;
the specific operation is as follows: 1) Putting the sodium metaaluminate solution into a reaction device, starting stirring, and heating to 70-80 ℃ for later use; 2) Uniformly mixing a sulfuric acid aqueous solution, stearic acid and aluminum sulfate for later use; 3) Dropwise adding the mixed solution prepared in the step 2) into the sodium metaaluminate solution prepared in the step 1) for 4-10h, controlling the temperature at 70-80 ℃ after dropwise adding, carrying out heat preservation reaction for 2h, filtering and separating reaction liquid, leaching filter cakes with hot water, and drying the filter cakes to obtain the superfine aluminum hydroxide with the specific oil absorption value.
2. The method for controlling the oil absorption value of the ultra-fine aluminum hydroxide as claimed in claim 1, wherein the concentration of the aqueous solution of sulfuric acid is 20-60%.
3. The method for controlling oil absorption of ultra-fine aluminum hydroxide as claimed in claim 1, wherein the stearic acid is added in an amount of 0.5-5% by mass based on the sodium metaaluminate solution.
4. The method for controlling the oil absorption of ultra-fine aluminum hydroxide as claimed in claim 1, wherein the amount of aluminum sulfate added is 0.3-2.5% by mass of the sodium metaaluminate solution.
5. The method for regulating and controlling the oil absorption value of the ultrafine aluminum hydroxide according to claim 1, wherein the equivalent ratio of the sodium metaaluminate to the sulfuric acid is 1: 0.98-1: 1.02.
6. The method for controlling the oil absorption value of the ultrafine aluminum hydroxide according to claim 1, wherein the filter cake is dried in the step 3), specifically at 150 ℃ for 4 h.
7. The method for controlling the oil absorption value of the superfine aluminum hydroxide product as claimed in claim 1, wherein the oil absorption value of the superfine aluminum hydroxide product prepared by the method is 20-80%.
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