Preparation method of dihydroxy aluminum monostearate

Abstract

The invention relates to a preparation method of dihydroxy aluminum monostearate, which is characterized by comprising the following steps: (1) mixing sodium hydroxide and water, heating to 60-95 DEG C, adding stearic acid with the same molar as the sodium hydroxide, and stirring to react for 0.05-0.5 hour to generate a sodium stearate solution; (2) aluminum salt is dissolved in water and added into the sodium stearate solution, a reaction is conducted for 0.5-2 h, and the molar ratio of aluminum ions to sodium stearate in the aluminum salt solution is (1-1.03): 1; (3) dissolving ammonium carbonate in water, adding into the reaction liquid in the step (2), and reacting for 0.5-2 hours; and (4) separating the solid, and drying to obtain the dihydroxy aluminum monostearate. According to the preparation method provided by the invention, the dihydroxy aluminum monostearate with high purity and small particle size can be obtained with high yield.

Description

Technical Field

[0001] This invention belongs to the field of metal soap preparation technology, specifically relating to a method for preparing aluminum dihydroxy monostearate. Background Technology

[0002] Aluminum monostearate, also known as aluminum monostearate, has the molecular formula C0. 17 H 35 COOAl(OH)2 can be used as a multifunctional surfactant, lubricant, defoamer and pharmaceutical excipient in many industrial fields.

[0003] The existing industrial preparation method for aluminum monostearate with dihydroxy acids is mainly the metathesis method. This involves using stearic acid and excess sodium hydroxide as raw materials, first saponifying them to produce sodium stearate, and then reacting it with an aluminum salt (such as aluminum sulfate, aluminum chloride, etc.) in a metathesis reaction (sodium hydroxide is present in the reaction system) to produce aluminum monostearate with dihydroxy acids. Because sodium hydroxide is a strong base, OH- ions displace the intermediate C... 17 H 35 COOAlSO4 SO4 2- Product C generated 17 H 35 When COOAl(OH)2 is used, it may also replace the C of the intermediate. 17 H 35 COO - Generate C 17 H 35 The presence of COONa and Al(OH)3 impurities makes it difficult to obtain high-purity aluminum monostearate with dihydroxy compounds. Furthermore, the product is prone to agglomeration, leading to larger particle sizes.

[0004] Therefore, developing new methods for preparing aluminum monostearate with dihydroxy compounds to avoid the formation of impurities and obtain high-purity aluminum monostearate products with small particle size remains a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing aluminum monostearate with hydroxyl groups.

[0006] This invention provides a method for preparing aluminum monostearate with hydroxyl groups: A method for preparing aluminum monostearate with dihydroxy, characterized by comprising the following steps: (1) Mix sodium hydroxide with water, heat to 60-95℃, add stearic acid in equimolar amounts with sodium hydroxide, stir and react for 0.05-0.5 h to generate sodium stearate solution; (2) Dissolve aluminum salt in water and add it to sodium stearate solution, and react for 0.5 to 2 h. The molar ratio of aluminum ions to sodium stearate in the aluminum salt solution is 1 to 1.03: 1. (3) Dissolve ammonium carbonate in water and add it to the reaction solution of step (2), and react for 0.5 to 2 h; (4) After separating and drying the solid, aluminum dihydroxy monostearate is obtained.

[0007] Furthermore, in step (1), the mass ratio of sodium hydroxide to water is 1:150-300.

[0008] Furthermore, the aluminum salt is aluminum chloride, aluminum sulfate, or aluminum nitrate.

[0009] Furthermore, in step (2), the mass ratio of aluminum salt to water is 1:5 to 20.

[0010] Furthermore, the molar ratio of ammonium carbonate to aluminum ions is 0.6–1.2:1.

[0011] Furthermore, in step (3), the mass ratio of ammonium carbonate to water is 1:4 to 10.

[0012] The beneficial effects of this invention are as follows: 1. This invention provides a novel synthesis method for aluminum monostearate with dihydroxy compounds. Compared with existing processes, this invention optimizes the process in two aspects: (1) Ammonium carbonate is used to replace sodium hydroxide in the traditional method. Ammonium carbonate provides a stable buffer system, keeping the pH of the system within the range of 7.5-8.5, making the reaction more complete and improving the selectivity of the dihydroxy target product, resulting in a higher purity final product; (2) In this invention, the aluminum salt solution is added after the reaction of stearic acid and alkali, avoiding side reactions caused by excessive local alkalinity, ensuring that the Al 3+ The complete reaction with stearate not only reduces aluminum salt waste and impurity formation, but also results in smaller particle size and better dispersibility of the product.

[0013] 2. This invention ensures that the aluminum center retains dihydroxyl groups (-OH) by controlling the order of material addition, as well as appropriate temperature and pH, ultimately forming stable dihydroxyl aluminum monostearate.

[0014] 3. In this invention, ammonium carbonate is used to replace part of the sodium hydroxide. Under these conditions, the OH- generated in the weakly alkaline reaction system... - Able to replace strong acid radicals (such as (C) in intermediates 17 H 35 Cl in COO)AlCl2 - However, it is difficult to displace stearate ions, thus effectively suppressing byproducts (such as Al(OH)3 and C). 17 H 35 The formation of COONa results in higher product purity.

[0015] 4. The technical solution of the present invention has the following advantages: (1) The product has high purity and no aluminum hydroxide impurities; (2) The product has small particle size and good dispersibility. Detailed Implementation

[0016] The specific embodiments of the present invention will be further described in detail below. For those skilled in the art, the above and other objects, features, and advantages of the present invention will become apparent from the detailed description.

[0017] The principle of this invention for preparing dihydroxy aluminum monostearate is as follows: First, sodium stearate is synthesized using stearic acid and sodium hydroxide as raw materials; second, an aluminum salt (such as aluminum chloride) solution is added to the sodium stearate solution, resulting in a metathesis reaction in which one stearate ion replaces the anion (such as Cl-) in the aluminum salt (such as aluminum chloride). - ), generating intermediates (C 17 H 35 COO)AlCl2; Finally, add a weakly alkaline ammonium carbonate solution, which reacts with two OH groups. - Replace the anions (such as Cl-) in aluminum salts (such as aluminum chloride). - ), to produce the product aluminum dihydroxy monostearate [C 17 H 35 COOAl(OH)2].

[0018] Example 1: 0.1 mol sodium hydroxide was mixed with 800 mL of water, heated to 75 °C, and 0.1 mol stearic acid was added. The mixture was stirred for 0.1 h to produce a 0.1 mol sodium stearate solution. 0.101 mol aluminum chloride was mixed with 150 mL of water to prepare an aluminum salt solution, which was then added to the sodium stearate solution and reacted for 1 h. 0.08 mol ammonium carbonate was dissolved in 60 mL of water and added to the reaction solution. The mixture was stirred for 1 h. After separating and drying the solid, aluminum dihydroxy monostearate was obtained.

[0019] Example 2: 0.1 mol sodium hydroxide was mixed with 1200 mL of water, heated to 85 °C, and 0.1 mol stearic acid was added. The mixture was stirred for 0.05 h to produce a 0.1 mol sodium stearate solution. 0.05 mol aluminum sulfate was mixed with 100 mL of water to prepare an aluminum salt solution, which was then added to the sodium stearate solution. The mixture was stirred for 0.5 h. 0.06 mol ammonium carbonate was dissolved in 50 mL of water and added to the reaction solution. The mixture was stirred for 2 h. After separating and drying the solid, aluminum dihydroxy monostearate was obtained.

[0020] Example 3: 0.1 mol sodium hydroxide was mixed with 600 mL of water, heated to 65 °C, and 0.1 mol stearic acid was added. The mixture was stirred for 0.5 h to produce a 0.1 mol sodium stearate solution. 0.103 mol aluminum nitrate was mixed with 250 mL of water to prepare an aluminum salt solution, which was then added to the sodium stearate solution and reacted for 2 h. 0.1 mol ammonium carbonate was dissolved in 40 mL of water and added to the reaction solution. The mixture was stirred for 0.5 h. After separating and drying the solid, aluminum dihydroxy monostearate was obtained.

[0021] Comparative Example 1: The preparation method is the same as in Example 1, except that ammonium carbonate is replaced with an equal amount of sodium hydroxide to obtain aluminum dihydroxy monostearate.

[0022] Product analysis and testing: The aluminum content and fineness of aluminum dihydroxy monostearate were analyzed according to the method in HG / T 3667-2012; the melt transparency was tested by melting the product at 250℃ and visually observing its melt transparency to determine whether there were infusible aluminum hydroxide impurities in the product; the yield was tested by dividing the mass of the solids after drying to constant weight by the theoretical yield and multiplying by 100% (based on the mass of the raw material stearic acid). The analysis and test results are shown in Table 1.

[0023]

[0024] Based on the results of Examples 1-3, the actual aluminum content of the product is close to the theoretical amount; after melting at 250°C, the product is highly transparent with no unmelted matter, indicating the absence of aluminum hydroxide impurities; the product can completely pass through a 0.075 mm sieve, indicating a small particle size; and the product yield is high (98.0–98.9%). Therefore, the technical solution provided by this invention can synthesize aluminum monostearate with both high purity and small particle size in high yield.

[0025] Based on the results of Example 1 and Comparative Example 1, in the intermediate (C) 17 H 35 COO)2AlCl is converted into the product (C 17 H 35 In the process of COO)2AlOH, replacing the strong base sodium hydroxide with the weak base ammonium carbonate can avoid the formation of Al(OH)3 impurities and result in high transparency in the molten state. Based on the reduction of impurities and the improvement of purity, the product yield using this technical solution is higher than that of the existing process.

[0026] It should be understood that although the present invention has been clearly described through the above embodiments, those skilled in the art can make various corresponding changes and modifications based on the present invention without departing from its spirit and essence, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing aluminum monostearate with hydroxyl groups, characterized in that, Includes the following steps: (1) Mix sodium hydroxide with water, heat to 60-95℃, add stearic acid in equimolar amounts with sodium hydroxide, stir and react for 0.05-0.5 h to generate sodium stearate solution; (2) Dissolve aluminum salt in water and add it to sodium stearate solution, and react for 0.5 to 2 h. The molar ratio of aluminum ions to sodium stearate in the aluminum salt solution is 1 to 1.03:

1. (3) Dissolve ammonium carbonate in water and add it to the reaction solution of step (2), and react for 0.5 to 2 h; (4) After separating and drying the solid, aluminum dihydroxy monostearate is obtained.

2. The method for preparing aluminum dihydroxy monostearate according to claim 1, characterized in that, In step (1), the mass ratio of sodium hydroxide to water is 1:150-300.

3. The method for preparing aluminum dihydroxy monostearate according to claim 1, characterized in that, The aluminum salt is aluminum chloride, aluminum sulfate, or aluminum nitrate.

4. The method for preparing aluminum dihydroxy monostearate according to claim 1, characterized in that, In step (2), the mass ratio of aluminum salt to water is 1:5 to 20.

5. The method for preparing aluminum dihydroxy monostearate according to claim 1, characterized in that, The molar ratio of ammonium carbonate to aluminum ions is 0.6–1.2:

1.

6. The method for preparing aluminum dihydroxy monostearate according to claim 1, characterized in that, In step (3), the mass ratio of ammonium carbonate to water is 1:4 to 10.

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