A kind of preparation method of calcium acetylacetonate

Abstract

The invention discloses a method for preparing calcium acetylacetonate, belonging to the technical field of chemical raw material preparation. The method comprises the following steps: impurity removal, precipitation, hydrophobic modification and reaction. The impurity removal comprises mixing industrial-grade anhydrous calcium chloride and deionized water, stirring, adjusting the pH value to 2-2.5, stirring, heating to 45-50 DEG C, dripping an aqueous solution of hydrogen peroxide, stirring, dripping dispersed lime milk to adjust the pH value to 7-7.5, stirring, filtering, taking a filtrate, adding activated carbon, stirring and filtering. The reaction comprises mixing acetylacetone and xylene, stirring at 100-110 DEG C, adding hydrophobically modified calcium hydroxide, stirring, filtering, taking a filter residue, washing and drying to obtain calcium acetylacetonate. The method can shorten the reaction time in the preparation, reduce the amount of acetylacetone used in the preparation, reduce the use of sodium hydroxide in the preparation, and improve the yield, purity, whiteness and storage stability of the obtained calcium acetylacetonate.

Description

Technical Field

[0001] The invention relates to the technical field of chemical raw material preparation, and in particular to a method for preparing calcium acetylacetonate. Background Art

[0002] Calcium acetylacetonate is a white powder with a characteristic odor, stable in nature, and easy to react with oxidants. Calcium acetylacetonate is a commonly used heat stabilizer in the processing of halogenated polymer products, especially in the processing of polyvinyl chloride products. In the process of thermal degradation, polyvinyl chloride will first remove hydrochloric acid molecules to form conjugated olefin chains. Since calcium acetylacetonate has a β-diketone structure, it can react with the removed hydrochloric acid molecules and the formed conjugated olefin chains to interrupt the conjugated olefin chains, thereby playing the role of a heat stabilizer. In addition, calcium acetylacetonate also has a significant synergistic effect with other heat stabilizers with a β-diketone structure. For example, after calcium acetylacetonate is mixed with stearylbenzoylmethane and dibenzoylmethane, the service life of halogenated polymer products can be greatly extended, so that halogenated polymer products can maintain their original color and transparency for a long time. Moreover, the cost performance of calcium acetylacetonate is better than that of organic tin heat stabilizers, and its environmental protection is better than that of lead salt stabilizers. Therefore, in recent years, the market demand for calcium acetylacetonate has continued to grow, and the market prospects are broad.

[0003] The traditional preparation method of calcium acetylacetonate is a liquid phase preparation method, specifically, sodium hydroxide is added to a calcium chloride aqueous solution for reaction, and then acetylacetone is added for reaction, and then separated to obtain calcium acetylacetonate. However, since the reaction is carried out in an aqueous environment, acetylacetone is prone to hydrolysis in the aqueous environment, resulting in partial loss of acetylacetone, and the reaction system is three-phase, and the reaction contact area between calcium hydroxide and acetylacetone is small, resulting in a long reaction time and low yield and purity of the obtained calcium acetylacetonate.

[0004] In order to solve the problems existing in the above-mentioned liquid phase preparation method, the inventor has tried a solid phase preparation method, specifically by mixing solid calcium hydroxide with acetylacetone, heating and reacting to obtain calcium acetylacetonate. It is found that although the method can avoid the loss of acetylacetone and simplify the separation step, due to the poor wettability of solid calcium hydroxide, the reaction contact area with acetylacetone is small, resulting in a long reaction time, and the reaction of solid calcium hydroxide is not thorough, further affecting the yield and purity of the calcium acetylacetonate obtained. Moreover, since solid calcium hydroxide contains iron and manganese impurities in the technical grade anhydrous calcium chloride used in the preparation, the solid calcium hydroxide obtained contains iron and manganese impurities, and iron acetylacetonate and manganese acetylacetonate are generated in the reaction, affecting the whiteness of calcium acetylacetonate, and further, affecting the appearance of halogenated polymer products.

[0005] In view of the above problems, there are currently three commonly used solutions: first, by increasing the amount of acetylacetone, the reaction contact area between solid calcium hydroxide and acetylacetone is increased, the reaction rate is increased, and the complete reaction of solid calcium hydroxide is achieved. However, this method will increase the amount of acetylacetone, further, resulting in an increase in raw material costs, and the effect of shortening the reaction time is not obvious; second, adding a dispersant, such as anhydrous ethanol and xylene, to the reaction to increase the reaction contact area between solid calcium hydroxide and acetylacetone, further, reduce the amount of acetylacetone, and improve the yield and purity of the obtained calcium acetylacetonate. However, when anhydrous ethanol is used as a dispersant, when preparing calcium acetylacetonate, the carbonyl oxygen atom in acetylacetone is used to form a bidentate coordination with calcium ions to form a stable six-membered chelate ring, and the hydroxyl group in anhydrous ethanol is easy to form a coordination bond with calcium ions. Anhydrous ethanol and acetylacetone compete with each other to coordinate with calcium ions. Since the coordination effect of acetylacetone and calcium ions is strong, calcium ions preferentially coordinate with acetylacetone, and anhydrous ethanol is through hydrogen. The bonding effect increases the stability of calcium acetylacetonate. Due to the strong affinity between anhydrous ethanol and acetylacetone, some anhydrous ethanol and acetylacetone will be present on the surface of the obtained calcium acetylacetonate. The presence of anhydrous ethanol will increase the hygroscopicity of calcium acetylacetonate, further, resulting in a decrease in the storage resistance of calcium acetylacetonate. The presence of acetylacetone will cause the calcium acetylacetonate to turn yellow, further, resulting in a decrease in the whiteness of calcium acetylacetonate. When xylene is used as a dispersant, since solid calcium hydroxide is a hydrophilic substance, xylene can only play a role in dispersing acetylacetone, and the effect of improving the wettability of solid calcium hydroxide is not obvious, resulting in an insignificant effect on shortening the reaction time. Third, the industrial-grade anhydrous calcium chloride used in the preparation of solid calcium hydroxide is impurity-removed, specifically by adjusting the pH to precipitate iron and manganese impurities. The commonly used pH adjusters are sodium hydroxide aqueous solution and lime milk, but when sodium hydroxide aqueous solution is used as a pH adjuster, the production cost will increase; when lime milk is used as a pH adjuster, the lime milk is unstable, which affects the impurity removal effect. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention provides a method for preparing calcium acetylacetonate, which can shorten the reaction time in the preparation, reduce the amount of acetylacetone used in the preparation, reduce the use of sodium hydroxide in the preparation, and improve the yield, purity, whiteness and storage stability of the obtained calcium acetylacetonate.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing calcium acetylacetonate, comprising the following steps: impurity removal, precipitation, hydrophobic modification, and reaction;

[0009] The impurity removal method comprises the following steps: mixing industrial-grade anhydrous calcium chloride and deionized water, stirring at room temperature at a stirring speed of 50-100 rpm for 25-35 min, dripping concentrated hydrochloric acid to adjust the pH value to 2-2.5, stirring for 10-20 min after the dripping is completed, heating to 45-50° C., dripping a hydrogen peroxide aqueous solution, stirring for 1.5-2 h after the dripping is completed, dripping dispersed lime milk to adjust the pH value to 7-7.5, stirring for 40-50 min after the dripping is completed, filtering, taking the filtrate, adding activated carbon to the filtrate, stirring at room temperature at a stirring speed of 50-100 rpm for 1.5-2 h, filtering, taking the filtrate, and obtaining a calcium chloride aqueous solution after impurity removal;

[0010] In the impurity removal, the mass volume ratio of industrial grade anhydrous calcium chloride, deionized water, aqueous hydrogen peroxide solution, and activated carbon is 500-550g:1000-1200mL:85-95mL:25-30g;

[0011] The purity of the industrial grade anhydrous calcium chloride is 92%;

[0012] The mass concentration of the concentrated hydrochloric acid is 37%, and the dropping speed is 2-3 mL / min;

[0013] The mass concentration of the aqueous hydrogen peroxide solution is 30%, and the dropping speed is 4-5 mL / min;

[0014] The preparation method of the dispersed lime milk comprises the following steps: mixing a first portion of deionized water and polyvinyl alcohol 1788, stirring the mixture at a stirring speed of 200-300 rpm for 15-20 minutes at room temperature, adding a first portion of high-purity calcium oxide, heating the mixture to 50-55° C. after the addition is completed, continuing to stir the mixture for 1-1.5 hours, and passing the mixture through a 100-mesh sieve to obtain highly dispersed lime milk; stirring a second portion of deionized water at a stirring speed of 200-300 rpm at room temperature, and then adding the second portion of high-purity calcium oxide, heating the mixture to 50-55° C. after the addition is completed, continuing to stir the mixture for 1-1.5 hours, and passing the mixture through a 100-mesh sieve to obtain lime milk; mixing all of the highly dispersed lime milk with the lime milk, stirring the mixture at a stirring speed of 200-300 rpm for 20-30 minutes at room temperature to obtain dispersed lime milk;

[0015] In the preparation of the dispersed lime milk, the mass volume ratio of the first portion of deionized water, polyvinyl alcohol 1788, the first portion of high-purity calcium oxide, the second portion of deionized water, and the second portion of high-purity calcium oxide is 200-230 mL: 10-15 g: 40-45 g: 2000-2300 mL: 400-450 g;

[0016] The addition rate of the first portion of high-purity calcium oxide is 2-3 g / min;

[0017] The second portion of high-purity calcium oxide is added at a rate of 30-35 g / min;

[0018] The purity of the high-purity calcium oxide is 99.5%;

[0019] The dropping speed of the dispersed lime milk is 18-20 mL / min;

[0020] The particle size of the activated carbon is 50 mesh;

[0021] The precipitation method comprises stirring the impurity-removed calcium chloride aqueous solution at a stirring speed of 200-300 rpm at room temperature, then dripping a sodium hydroxide aqueous solution to adjust the pH to 10-10.5, adding nanometer high-purity calcium hydroxide after the dripping, stirring for 10-15 minutes, hydrothermally reacting at 160-170° C. for 10-11 hours, filtering, taking the filter residue, washing it with deionized water, and drying it to obtain calcium hydroxide;

[0022] In the precipitate, the purity of the nano high-purity calcium hydroxide is 99.5% and the particle size is 100 nm;

[0023] The mass concentration of the sodium hydroxide aqueous solution is 30%, and the dropping speed is 8-10 mL / min;

[0024] The mass ratio of the industrial-grade anhydrous calcium chloride in the impurity removal to the nanometer high-purity calcium hydroxide in the precipitation is 500-550:15-16;

[0025] The hydrophobic modification method comprises mixing calcium hydroxide and xylene, stirring at room temperature at a stirring speed of 200-300 rpm for 30-40 minutes, heating to 80-90° C., adding hexadecyltrimethoxysilane and triethylamine, stirring for 11-12 hours, filtering, taking the filter residue, washing it with xylene, and drying it to obtain hydrophobically modified calcium hydroxide;

[0026] In the hydrophobic modification, the mass volume ratio of calcium hydroxide, xylene, hexadecyltrimethoxysilane and triethylamine is 200-210 g: 4000-4500 mL: 40-50 mL: 4-5 mL;

[0027] The reaction method comprises the following steps: mixing acetylacetone and xylene, stirring at 100-110° C. and 300-400 rpm for 5-6 minutes, adding hydrophobically modified calcium hydroxide, stirring for 30-35 minutes, filtering, taking filter residue and filtrate, washing the filter residue with xylene, and drying to obtain calcium acetylacetonate; and recovering xylene after dehydrating the filtrate.

[0028] The mass volume ratio of acetylacetone, xylene in the reaction to calcium hydroxide in the hydrophobic modification is 200-210 g: 610-670 mL: 2700-2900 mL.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The preparation method of calcium acetylacetonate of the present invention uses dispersed lime milk in the impurity removal step. The dispersed lime milk is prepared by mixing highly dispersed lime milk and lime milk. Polyvinyl alcohol is added to the highly dispersed lime milk during preparation. The polyvinyl alcohol plays a role in controlling the particle size and can be coated on the surface of calcium hydroxide to shield the hydroxyl groups on the surface of calcium hydroxide particles, thereby preventing the calcium hydroxide particles from bridging through the hydroxyl groups, which results in the calcium hydroxide particles being too large and easy to precipitate, thereby obtaining highly dispersed lime milk. The highly dispersed lime milk and lime milk are then mixed, and the calcium hydroxide particles coated with polyvinyl alcohol are uniformly dispersed, further reducing the interaction between calcium hydroxide in the dispersed lime milk and improving the dispersibility of calcium hydroxide in the dispersed lime milk. After the dispersed lime milk is added to the calcium chloride aqueous solution, the calcium hydroxide in the lime milk is first dissolved, and then the calcium hydroxide in the highly dispersed lime milk is dissolved. Calcium is gradually dissolved to avoid excessively fast dissolution speed, which may result in incomplete dissolution of calcium hydroxide in the later stage of pH adjustment, and coagulation caused by continuous hydrogen bonding between calcium hydroxides, which may result in unstable pH and affect the removal of iron and manganese ions. In addition, nanometer high-purity calcium hydroxide is added to the precipitate, which plays a dispersing role in the hydrothermal process, avoids excessive calcium hydroxide particle size, increases the specific surface area and activity of calcium hydroxide, and is more conducive to later hydrophobic modification. In the hydrophobic modification, hexadecyltrimethoxysilane is used to modify calcium hydroxide, so as to graft hydrophobic groups on the surface of calcium hydroxide. In the reaction, since hexadecyltrimethoxysilane is easily soluble in xylene, it can promote the wetting effect of xylene on calcium hydroxide and promote the contact between acetylacetone and calcium hydroxide, so as to shorten the reaction time in the preparation and reduce the amount of acetylacetone in the preparation.

[0031] (2) The preparation method of calcium acetylacetonate of the present invention can reduce the use of sodium hydroxide in the preparation by using lime milk instead of calcium hydroxide in the process of pH adjustment;

[0032] (3) The preparation method of calcium acetylacetonate of the present invention can improve the whiteness of the obtained calcium acetylacetonate, and the whiteness of the obtained calcium acetylacetonate is 87.04-87.59%;

[0033] (4) The preparation method of calcium acetylacetonate of the present invention can improve the purity and yield of the obtained calcium acetylacetonate. The purity of the obtained calcium acetylacetonate is 98.1-98.4%, and the yield is 94.1-95.3%;

[0034] (5) The preparation method of calcium acetylacetonate of the present invention can improve the storage stability of the obtained calcium acetylacetonate. The calcium acetylacetonate obtained by the present invention is placed in an open environment with a temperature of 25° C. and a relative humidity of 60% for storage. After storage for 30 days, it is not affected by moisture. DETAILED DESCRIPTION

[0035] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific implementation methods of the present invention are now described.

[0036] Example 1

[0037] A preparation method of calcium acetylacetonate, specifically:

[0038] 1. Impurity removal: 500g of industrial grade anhydrous calcium chloride and 1000mL of deionized water were mixed, stirred at room temperature at a stirring speed of 50rpm for 25min, concentrated hydrochloric acid was added dropwise to adjust the pH to 2, stirred for 10min after the addition was completed, the temperature was raised to 45°C, 85mL of hydrogen peroxide solution was added dropwise, stirred for 1.5h after the addition was completed, dispersed lime milk was added dropwise to adjust the pH to 7, stirred for 40min after the addition was completed, filtered, and the filtrate was taken. 25g of activated carbon was added to the filtrate, stirred at room temperature at a stirring speed of 50rpm for 1.5h, filtered, and the filtrate was taken to obtain a calcium chloride aqueous solution after impurities were removed;

[0039] The purity of the industrial grade anhydrous calcium chloride is 92%;

[0040] The mass concentration of the concentrated hydrochloric acid is 37%, and the dropping speed is 2 mL / min;

[0041] The mass concentration of the aqueous hydrogen peroxide solution is 30%, and the dropping speed is 4 mL / min;

[0042] The preparation method of the dispersed lime milk is as follows: 200 mL of deionized water and 10 g of polyvinyl alcohol 1788 are mixed, and the mixture is stirred at a stirring speed of 200 rpm for 15 min at room temperature, and 40 g of high-purity calcium oxide is slowly added at a rate of 2 g / min, and after the addition is completed, the mixture is heated to 50° C., stirred for 1 h, and passed through a 100-mesh sieve to obtain highly dispersed lime milk; 2000 mL of deionized water is stirred at a stirring speed of 200 rpm at room temperature, and then 400 g of high-purity calcium oxide is slowly added at a rate of 30 g / min, and after the addition is completed, the mixture is heated to 50° C., stirred for 1 h, and passed through a 100-mesh sieve to obtain lime milk; all of the highly dispersed lime milks are mixed with the lime milk, and stirred at a stirring speed of 200 rpm for 20 min at room temperature to obtain dispersed lime milk;

[0043] The purity of the high-purity calcium oxide is 99.5%;

[0044] The dropping speed of the dispersed lime milk is 18 mL / min;

[0045] The particle size of the activated carbon is 50 mesh;

[0046] 2. Precipitation: Stir the calcium chloride aqueous solution obtained in step 1 at room temperature at a stirring speed of 200 rpm, then add sodium hydroxide aqueous solution to adjust the pH to 10, add 15 g of nanometer high-purity calcium hydroxide after the addition is completed, stir for 10 minutes, hydrothermally react at 160° C. for 10 hours, filter, take the filter residue, wash it with deionized water, and dry it to obtain calcium hydroxide;

[0047] The purity of the nano high-purity calcium hydroxide is 99.5% and the particle size is 100nm;

[0048] The mass concentration of the sodium hydroxide aqueous solution is 30%, and the dropping speed is 8 mL / min;

[0049] 3. Hydrophobic modification: 200 g of the calcium hydroxide obtained in step 2 and 4000 mL of xylene were mixed, stirred at room temperature at a stirring speed of 200 rpm for 30 min, heated to 80° C., 40 mL of hexadecyltrimethoxysilane and 4 mL of triethylamine were added, stirred for 11 h, filtered, the filter residue was taken, washed with xylene, and dried to obtain hydrophobically modified calcium hydroxide;

[0050] 4. Reaction: Mix 610 mL of acetylacetone and 2700 mL of xylene, stir at 100°C at a stirring speed of 300 rpm for 5 min, add all the hydrophobically modified calcium hydroxide obtained in step 3, stir for 30 min, filter, take the filter residue and filtrate, wash the filter residue with xylene, and dry to obtain calcium acetylacetonate; dehydrate the filtrate and recover the xylene.

[0051] A total of 617.2 g of calcium acetylacetonate was obtained in the reaction of step 4 of this embodiment.

[0052] Example 2

[0053] A preparation method of calcium acetylacetonate, specifically:

[0054] 1. Impurity removal: 520g of industrial grade anhydrous calcium chloride and 1100mL of deionized water were mixed, stirred at room temperature at a stirring speed of 80rpm for 30min, concentrated hydrochloric acid was added dropwise to adjust the pH to 2.2, stirred for 15min after the addition was completed, the temperature was raised to 48°C, 90mL of hydrogen peroxide solution was added dropwise, stirred for 1.5h after the addition was completed, dispersed lime milk was added dropwise to adjust the pH to 7.2, stirred for 45min after the addition was completed, filtered, and the filtrate was taken. 28g of activated carbon was added to the filtrate, stirred at room temperature at a stirring speed of 80rpm for 1.5h, filtered, and the filtrate was taken to obtain a calcium chloride aqueous solution after impurities were removed;

[0055] The purity of the industrial grade anhydrous calcium chloride is 92%;

[0056] The mass concentration of the concentrated hydrochloric acid is 37%, and the dropping speed is 2 mL / min;

[0057] The mass concentration of the aqueous hydrogen peroxide solution is 30%, and the dropping speed is 4 mL / min;

[0058] The preparation method of the dispersed lime milk is as follows: 220 mL of deionized water and 12 g of polyvinyl alcohol 1788 are mixed, and the mixture is stirred at a stirring speed of 250 rpm for 18 min at room temperature, and 42 g of high-purity calcium oxide is slowly added at a rate of 2 g / min. After the addition is completed, the mixture is heated to 52° C., stirred for 1.5 h, and passed through a 100-mesh sieve to obtain highly dispersed lime milk; 2200 mL of deionized water is stirred at a stirring speed of 250 rpm at room temperature, and then 420 g of high-purity calcium oxide is slowly added at a rate of 32 g / min. After the addition is completed, the mixture is heated to 52° C., stirred for 1.5 h, and passed through a 100-mesh sieve to obtain lime milk; all of the highly dispersed lime milks are mixed with the lime milk, and stirred at a stirring speed of 250 rpm for 25 min at room temperature to obtain dispersed lime milk;

[0059] The purity of the high-purity calcium oxide is 95%;

[0060] The dropping speed of the dispersed lime milk is 20 mL / min;

[0061] The particle size of the activated carbon is 50 mesh;

[0062] 2. Precipitation: Stir the calcium chloride aqueous solution obtained in step 1 after impurities removal at a stirring speed of 250 rpm at room temperature, then add sodium hydroxide aqueous solution to adjust the pH to 10.5, add 15.5 g of nanometer high-purity calcium hydroxide after the addition is completed, stir for 12 minutes, hydrothermally react at 165° C. for 10.5 hours, filter, take the filter residue, wash it with deionized water, and dry it to obtain calcium hydroxide;

[0063] The purity of the nano high-purity calcium hydroxide is 99.5% and the particle size is 100nm;

[0064] The mass concentration of the sodium hydroxide aqueous solution is 30%, and the dropping speed is 9 mL / min;

[0065] 3. Hydrophobic modification: 205 g of the calcium hydroxide obtained in step 2 and 4200 mL of xylene were mixed, stirred at room temperature at a stirring speed of 250 rpm for 35 min, heated to 85 ° C, added with 45 mL of hexadecyltrimethoxysilane and 5 mL of triethylamine, stirred for 11.5 h, filtered, and the filter residue was washed with xylene and dried to obtain hydrophobically modified calcium hydroxide;

[0066] 4. Reaction: Mix 650 mL of acetylacetone and 2800 mL of xylene, stir at 105°C at a stirring speed of 350 rpm for 6 min, add all the hydrophobically modified calcium hydroxide obtained in step 3, stir for 32 min, filter, take the filter residue and filtrate, wash the filter residue with xylene, and dry to obtain calcium acetylacetonate; dehydrate the filtrate and recover the xylene.

[0067] In the fourth step of the present embodiment, a total of 638.3 g of calcium acetylacetonate was obtained.

[0068] Example 3

[0069] A preparation method of calcium acetylacetonate, specifically:

[0070] 1. Impurity removal: 550g of industrial grade anhydrous calcium chloride and 1200mL of deionized water were mixed, stirred at room temperature at a stirring speed of 100rpm for 35min, concentrated hydrochloric acid was added dropwise to adjust the pH to 2.5, stirred for 20min after the addition was completed, the temperature was raised to 50°C, 95mL of hydrogen peroxide aqueous solution was added dropwise, stirred for 2h after the addition was completed, dispersed lime milk was added dropwise to adjust the pH to 7.5, stirred for 50min after the addition was completed, filtered, and the filtrate was taken. 30g of activated carbon was added to the filtrate, stirred at room temperature at a stirring speed of 100rpm for 2h, filtered, and the filtrate was taken to obtain an impurity-removed calcium chloride aqueous solution;

[0071] The purity of the industrial grade anhydrous calcium chloride is 92%;

[0072] The mass concentration of the concentrated hydrochloric acid is 37%, and the dropping speed is 3 mL / min;

[0073] The mass concentration of the aqueous hydrogen peroxide solution is 30%, and the dropping speed is 5 mL / min;

[0074] The preparation method of the dispersed lime milk is as follows: 230 mL of deionized water and 15 g of polyvinyl alcohol 1788 are mixed, and the mixture is stirred at a stirring speed of 300 rpm for 20 min at room temperature, and 45 g of high-purity calcium oxide is slowly added at a rate of 3 g / min, and after the addition is completed, the mixture is heated to 55° C., stirred for 1.5 h, and passed through a 100-mesh sieve to obtain highly dispersed lime milk; 2300 mL of deionized water is stirred at a stirring speed of 300 rpm at room temperature, and then 450 g of high-purity calcium oxide is slowly added at a rate of 35 g / min, and after the addition is completed, the mixture is heated to 55° C., stirred for 1.5 h, and passed through a 100-mesh sieve to obtain lime milk; all of the highly dispersed lime milks are mixed with the lime milk, and stirred at a stirring speed of 300 rpm for 30 min at room temperature to obtain dispersed lime milk;

[0075] The purity of the high-purity calcium oxide is 95%;

[0076] The dropping speed of the dispersed lime milk is 20 mL / min;

[0077] The particle size of the activated carbon is 50 mesh;

[0078] 2. Precipitation: Stir the calcium chloride aqueous solution obtained in step 1 at room temperature at a stirring speed of 300 rpm, then add sodium hydroxide aqueous solution to adjust the pH to 10.5, add 16 g of nanometer high-purity calcium hydroxide after the addition is completed, stir for 15 minutes, hydrothermally react at 170° C. for 11 hours, filter, take the filter residue, wash with deionized water, and dry to obtain calcium hydroxide;

[0079] The purity of the nano high-purity calcium hydroxide is 99.5% and the particle size is 100nm;

[0080] The mass concentration of the sodium hydroxide aqueous solution is 30%, and the dropping speed is 10 mL / min;

[0081] 3. Hydrophobic modification: 210 g of the calcium hydroxide obtained in step 2 and 4500 mL of xylene were mixed, stirred at room temperature at a stirring speed of 300 rpm for 40 min, heated to 90°C, 50 mL of hexadecyltrimethoxysilane and 5 mL of triethylamine were added, stirred for 12 h, filtered, the filter residue was taken, washed with xylene, and dried to obtain hydrophobically modified calcium hydroxide;

[0082] 4. Reaction: Mix 670 mL of acetylacetone and 2900 mL of xylene, stir at 110° C. at a stirring speed of 400 rpm for 6 min, add all the hydrophobically modified calcium hydroxide obtained in step 3, stir for 35 min, filter, take the filter residue and filtrate, wash the filter residue with xylene, and dry to obtain calcium acetylacetonate; dehydrate the filtrate and recover the xylene.

[0083] A total of 652.6 g of calcium acetylacetonate was obtained in the reaction of step 4 of this embodiment.

[0084] Comparative Example 1

[0085] This comparative example is adjusted on the basis of the preparation method of calcium acetylacetonate in Example 2, and the specific adjustments are as follows:

[0086] In the first step of impurity removal, the preparation method of dispersed lime milk is changed to:

[0087] 2200 mL of deionized water was stirred at a stirring speed of 250 rpm at room temperature, and then 420 g of high-purity calcium oxide was slowly added at a rate of 32 g / min. After the addition was completed, the temperature was raised to 52° C. and the stirring was continued for 1.5 h. The mixture was passed through a 100-mesh sieve to obtain dispersed lime milk;

[0088] The purity of the high-purity calcium oxide is 99.5%;

[0089] That is, in the preparation of dispersed lime milk, the addition of highly dispersed lime milk is omitted, that is, the lime milk is directly used as dispersed lime milk.

[0090] A total of 636.4 g of calcium acetylacetonate was obtained in the reaction of step 4 of this embodiment.

[0091] Comparative Example 2

[0092] This comparative example is adjusted on the basis of the preparation method of calcium acetylacetonate in Example 2, and the specific adjustments are as follows:

[0093] In the second precipitation step, the addition of 15.5 g of nano high-purity calcium hydroxide is omitted, and the third step of hydrophobic modification is omitted. Accordingly, 205 g of the calcium hydroxide obtained in the second precipitation step is taken and directly used in the fourth step reaction to replace the hydrophobically modified calcium hydroxide.

[0094] In the fourth step of the present embodiment, a total of 530.3 g of calcium acetylacetonate was obtained.

[0095] Comparative Example 3

[0096] This comparative example is adjusted on the basis of the preparation method of calcium acetylacetonate in comparative example 2, and the specific adjustments are as follows:

[0097] In the fourth reaction step, the amount of acetylacetone was increased from 650 mL to 1300 mL.

[0098] In the fourth step of the present embodiment, a total of 598.0 g of calcium acetylacetonate was obtained.

[0099] Comparative Example 4

[0100] This comparative example is adjusted on the basis of the preparation method of calcium acetylacetonate in comparative example 2, and the specific adjustments are as follows:

[0101] In the fourth reaction step, the stirring time after adding all the hydrophobically modified calcium hydroxide obtained in the third step was increased from 32 min to 64 min.

[0102] In the fourth step of the present embodiment, a total of 630.1 g of calcium acetylacetonate was obtained.

[0103] Comparative Example 5

[0104] This comparative example is adjusted on the basis of the preparation method of calcium acetylacetonate in comparative example 2, and the specific adjustments are as follows:

[0105] In the reaction step 4, an equal volume of anhydrous ethanol was used to replace xylene, the reaction temperature was changed from 105°C to 70°C, and the subsequent "washing the filter residue with xylene" was changed to "washing the filter residue with anhydrous ethanol".

[0106] A total of 641.2 g of calcium acetylacetonate was obtained in the reaction of step 4 of this embodiment.

[0107] Test Example 1

[0108] The calcium content and whiteness of the calcium acetylacetonate obtained in Examples 1-3 and Comparative Examples 1-4 were tested, and the test results are as follows:

[0109]

[0110] Test Example 2

[0111] Considering that the reactions in Examples 1-3 and Comparative Examples 1-5 were not carried out in an aqueous environment, and a drying step was added after the reaction, the water content in the finally obtained calcium acetylacetonate was low and negligible. If the purity of calcium acetylacetonate is directly detected, it is difficult, so in production, the quality of calcium acetylacetonate is generally judged by whether the calcium content in calcium acetylacetonate is within the range of 16.6-17.5%. In this test example, in order to be able to make further comparisons, the purity of calcium acetylacetonate is inferred by the calcium content, and the specific inference method is as follows:

[0112] Assuming that the final calcium acetylacetonate contains only calcium acetylacetonate and calcium hydroxide, the purity of the final calcium acetylacetonate can be inferred based on the calcium content in Test Example 1. The inference process is: Since the molecular formula of calcium acetylacetonate is C 10 H 14CaO4, the molecular formula of calcium hydroxide is Ca(OH)2. According to the molecular formula, the calcium content in calcium acetylacetonate is 0.168, and the calcium content in calcium hydroxide is 0.541. Assuming that the purity of calcium acetylacetonate is x, the calcium content = [the mass of calcium acetylacetonate × x × 0.168 + the mass of calcium acetylacetonate × (1-x) × 0.541] / the mass of calcium acetylacetonate = x × 0.168 + (1-x) × 0.541 = 0.541-0.373x;

[0113] Therefore, the purity of calcium acetylacetonate x = (0.541-calcium content) / 0.373;

[0114] Substituting the calcium content in Test Example 1 into the calculation formula for the purity of calcium acetylacetonate, the purity of calcium acetylacetonate obtained is as follows:

[0115]

[0116] Then, the yield was calculated based on the purity and the mass of calcium acetylacetonate obtained in Examples 1-3 and Comparative Examples 1-5. The calculation formula and results of the yield of calcium acetylacetonate in Examples 1-3 and Comparative Example 1 are as follows:

[0117] The yield of calcium acetylacetonate = (the mass of calcium acetylacetonate × the purity of calcium acetylacetonate) / (the amount of calcium hydroxide used in the hydrophobic modification in step 3 / 74.093 × 238.294);

[0118] The calculation formula and calculation results of the yield of calcium acetylacetonate in Comparative Examples 2-5 are as follows:

[0119] The yield of calcium acetylacetonate = (the mass of calcium acetylacetonate × the purity of calcium acetylacetonate) / (205 / 74.093 × 238.294);

[0120]

[0121] The purity and yield of calcium acetylacetonate obtained by the above method can only be used as a reference. For Comparative Examples 1 and 5, since the whiteness of the obtained calcium acetylacetonate is low, it means that the impurity content is high, that is, the obtained calcium acetylacetonate contains other impurities in addition to calcium acetylacetonate and calcium hydroxide. Therefore, for Comparative Examples 1 and 5, the accuracy of the above method is low.

[0122] Test Example 3

[0123] 200 g of calcium acetylacetonate obtained in Examples 1-3 and Comparative Examples 1-5 were taken respectively and placed in a beaker, and then placed in an open environment at a temperature of 25° C. and a relative humidity of 60% for storage. After storage for 30 days, whether it was damp was observed. The observation results were as follows:

[0124]

[0125] It can be seen from the results of Test Examples 1-3 that in Comparative Example 1, no highly dispersed lime milk was added to the dispersed lime milk used in the first impurity removal step, resulting in low whiteness of the obtained calcium acetylacetonate. It is inferred that the iron ions or manganese ions may not be completely removed, resulting in trace iron ions or manganese ions still existing in the obtained calcium hydroxide, affecting the whiteness of the obtained calcium acetylacetonate;

[0126] In Comparative Example 2, nanometer high-purity calcium hydroxide was not added in the second precipitation step, and hydrophobically modified calcium hydroxide was not added in the fourth reaction step, resulting in the calcium content of the obtained calcium acetylacetonate exceeding the standard, and the purity and yield were low;

[0127] Comparative Example 3 is based on Comparative Example 2, but the amount of acetylacetone is increased. Compared with Comparative Example 2, the calcium content, purity and yield of the obtained calcium acetylacetonate are improved;

[0128] Comparative Example 4 is based on Comparative Example 2, but the reaction time is prolonged. Compared with Comparative Example 2, the calcium content, purity and yield of the obtained calcium acetylacetonate are improved;

[0129] Comparative Example 5 is based on Comparative Example 2, in which an equal volume of anhydrous ethanol is used instead of xylene, and the reaction temperature is lowered. Although the calcium content, purity and yield of the obtained calcium acetylacetonate are improved relative to Comparative Example 2, the whiteness of the obtained calcium acetylacetonate is reduced and it is susceptible to moisture. Considering that the calcium acetylacetonate prepared in Comparative Example 5 may contain acetylacetone, and acetylacetone does not contain calcium, the purity and yield of the calcium acetylacetonate obtained according to the method of Test Example 2 will be higher.

[0130] Unless otherwise specified, all percentages used in the present invention are by mass.

[0131] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing calcium acetylacetonate, characterized in that: The method consists of the following steps: impurity removal, precipitation, hydrophobic modification, and reaction; The impurity removal method comprises mixing industrial-grade anhydrous calcium chloride and deionized water, stirring at room temperature, adjusting the pH to 2-2.5, stirring after the dropwise addition is completed, heating to 45-50° C., dropping a hydrogen peroxide aqueous solution, stirring after the dropwise addition is completed, dropping dispersed lime milk to adjust the pH to 7-7.5, stirring after the dropwise addition is completed, filtering, taking a filtrate, adding activated carbon to the filtrate, stirring at room temperature, filtering, taking a filtrate, and obtaining a calcium chloride aqueous solution after impurities have been removed; The preparation method of the dispersed lime milk comprises the following steps: mixing a first portion of deionized water and polyvinyl alcohol 1788, stirring at room temperature, adding a first portion of high-purity calcium oxide, heating to 50-55° C. after the addition is completed, continuing to stir, sieving, and obtaining highly dispersed lime milk; stirring a second portion of deionized water at room temperature, then adding a second portion of high-purity calcium oxide, heating to 50-55° C. after the addition is completed, continuing to stir, sieving, and obtaining lime milk; mixing the highly dispersed lime milk with the lime milk, stirring at room temperature, and obtaining dispersed lime milk; The precipitation method comprises the following steps: stirring the impurity-removed calcium chloride aqueous solution at room temperature, then dripping a sodium hydroxide aqueous solution to adjust the pH to 10-10.5, adding nanometer high-purity calcium hydroxide after the dripping, stirring, hydrothermally reacting at 160-170° C. for 10-11 hours, filtering, taking the filter residue, washing, and drying to obtain calcium hydroxide; The hydrophobic modification method comprises mixing calcium hydroxide and xylene, stirring at room temperature, heating to 80-90° C., adding hexadecyltrimethoxysilane and triethylamine, stirring, filtering, taking the filter residue, washing, and drying to obtain hydrophobically modified calcium hydroxide; The reaction method comprises the following steps: mixing acetylacetone and xylene, stirring at 100-110° C., adding hydrophobically modified calcium hydroxide, stirring, filtering, taking the filter residue, washing, and drying to obtain calcium acetylacetonate.

2. The method for preparing calcium acetylacetonate according to claim 1, wherein In the impurity removal, the usage ratio of industrial-grade anhydrous calcium chloride, deionized water, aqueous hydrogen peroxide solution and activated carbon is 500-550g:1000-1200mL:85-95mL:25-30g.

3. The method for preparing calcium acetylacetonate according to claim 1, characterized in that: In the impurity removal, the purity of the industrial grade anhydrous calcium chloride is 92%; The mass concentration of the aqueous hydrogen peroxide solution is 30%, and the dropping speed is 4-5 mL / min.

4. The method for preparing calcium acetylacetonate according to claim 1, wherein In the preparation of the dispersed lime milk, the usage ratio of the first portion of deionized water, polyvinyl alcohol 1788, the first portion of high-purity calcium oxide, the second portion of deionized water, and the second portion of high-purity calcium oxide is 200-230 mL: 10-15 g: 40-45 g: 2000-2300 mL: 400-450 g.

5. The method for preparing calcium acetylacetonate according to claim 1, characterized in that: In the preparation of the dispersed lime milk, the first portion of high-purity calcium oxide is added at a rate of 2-3 g / min; The second portion of high-purity calcium oxide is added at a rate of 30-35 g / min; The purity of the high-purity calcium oxide is 99.5%.

6. The method for preparing calcium acetylacetonate according to claim 1, characterized in that: During the impurity removal, the dropping speed of the dispersed lime milk is 18-20 mL / min; The particle size of the activated carbon is 50 mesh.

7. The method for preparing calcium acetylacetonate according to claim 1, characterized in that: In the precipitate, the purity of the nano high-purity calcium hydroxide is 99.5% and the particle size is 100 nm; The mass concentration of the sodium hydroxide aqueous solution is 30%, and the dropping speed is 8-10 mL / min.

8. The method for preparing calcium acetylacetonate according to claim 1, characterized in that: The mass ratio of the industrial-grade anhydrous calcium chloride in the impurity removal to the nanometer high-purity calcium hydroxide in the precipitation is 500-550:15-16.

9. The method for preparing calcium acetylacetonate according to claim 1, characterized in that: In the hydrophobic modification, the mass volume ratio of calcium hydroxide, xylene, hexadecyltrimethoxysilane and triethylamine is 200-210g:4000-4500mL:40-50mL:4-5mL.

10. The method for preparing calcium acetylacetonate according to claim 1, characterized in that: The dosage ratio of acetylacetone and xylene in the reaction to calcium hydroxide in the hydrophobic modification is 610-670 mL: 2700-2900 mL: 200-210 g.

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