Diisononyl azelate as well as preparation method and application thereof

Abstract

The invention relates to the technical field of organic synthesis, in particular to diisononyl azelate and a preparation method and application thereof.The preparation method of the diisononyl azelate comprises the steps that 1, azelaic acid and isononyl alcohol are put into a reaction kettle, nitrogen is introduced to normal pressure, and then heating is started; step 2, raising the temperature of the reaction kettle to 130-140 DEG C, preserving heat for 3-5 hours at normal pressure, raising the temperature to 180-185 DEG C, and adjusting a valve to enable the recovered alcohol to flow back; 3, continuing to heat to 185-190 DEG C, and adding a catalyst; step 4, heating to 225-228 DEG C under the condition of no explosive boiling, carrying out constant-temperature reaction, and terminating the reaction when the acid value is less than 0.1; and 5, cooling to 85-90 DEG C, adding caustic soda liquid and deionized water, stirring, standing, layering water and ester, and removing water to obtain the diisononyl azelate. The prepared diisononyl azelate can significantly improve the tensile strength, breaking stress and elongation at break of plastic products.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of organic synthesis, more particularly, it relates to diisononyl azelate and a preparation method thereof, and is applied to the field of plastic processing. BACKGROUND

[0002] Azelic acid, as a straight-chain saturated dicarboxylic acid containing 9 carbon atoms, has unique biological properties. In medicine, its 20% cream can treat acne, and can also deal with rosacea, hyperpigmentation, etc., and has anti-inflammatory and antibacterial properties. However, in actual application, the local acne treatment effect is low, a high concentration is required, and it is often accompanied by a burning sensation, and the biological absorption and excretion characteristics are not good, which limits its use. Preparing azelate from azelic acid is the improvement direction, and diisononyl azelate is an important derivative of azelic acid, which is widely used in the field of plastic processing.

[0003] At present, the methods for preparing diisononyl azelate include ester exchange method, direct esterification method, etc., and a protonic acid is commonly used as a catalyst. However, these methods have complex post-treatment, require neutralization, water washing, and distillation, the product quality is greatly affected by the reaction conditions, the color is deep, there are many side reactions, the product yield is low, and a large amount of pollutants will be generated. Based on the above statement, the present application provides a method for preparing diisononyl azelate with high efficiency, environmental protection, low cost and high quality, which expands its application in the field of plastic processing. SUMMARY

[0004] In order to solve the technical problems mentioned in the background art, the present application provides diisononyl azelate and a preparation method and application thereof.

[0005] The present application provides a preparation method of diisononyl azelate, which adopts the following technical scheme: A preparation method of diisononyl azelate, comprising the following preparation steps: Step 1, azelic acid and isononyl alcohol are sequentially put into a reaction kettle, after the feeding is completed, vacuum is extracted, when the vacuum degree is-0.098-0.2 MPa, the vacuum pump is closed and the nitrogen valve is opened, nitrogen is passed to normal pressure, heating is started, and the circulating water of the condensation system is opened; Step 2, the reaction kettle is heated to 130-140 DEG C, normal pressure is maintained for 3-5 h, heating is continued to 180-185 DEG C, the alcohol recovery pipeline is opened, and the valve is adjusted to make the recovered alcohol reflux into the reaction kettle; Step 3, continue to heat to 185-190 DEG C, and add a catalyst; Step 4, in the case of no boiling, heat to 225-228 DEG C, and maintain 0.1-0.2 MPa constant temperature reaction, and the reaction is terminated when the acid value is less than 0.1; Step 5, the reactor is cooled to 85-90℃, liquid alkali and deionized water are added, stirred for 20-40min, and then stand for 20-30min, the water ester is separated, and the water is removed, to obtain diisononyl azelate.

[0006] Preferably, the mass ratio of azelaic acid and isononyl alcohol in step 1 is 12-13:23-26.

[0007] Preferably, in step 2, the temperature is raised in stages, first at 3-5℃ / min to 110-120℃, and then at 1-2℃ / min to 130-140℃.

[0008] Preferably, in step 2, the temperature is raised at a rate of 2-4℃ / min when the temperature is raised to 180-185℃.

[0009] Preferably, in step 2, the alcohol flow rate is 10-15L / h.

[0010] Preferably, in step 3, the temperature is raised to 185-190℃, and during the addition of the catalyst, the allowable temperature fluctuation range is ±1.5℃. Preferably, in step 3, the catalyst is one of titanium isopropylate, titanium tetrabutylate, and titanium tetraethylate.

[0011] Preferably, in step 4, the temperature is raised to 225-228℃ at a rate of 5-8℃ / min.

[0012] Preferably, in step 5, the temperature is cooled to 85-90℃ at a rate of 1-2℃ / min.

[0013] Preferably, the rotation speed of the reactor is 300-500rpm.

[0014] The diisononyl azelate prepared by the above preparation method is applied in plastic processing, coatings, and cosmetics.

[0015] In summary, the present application has the following beneficial effects: The application provides a preparation method of diisononyl azelate. The method comprises the following steps: firstly, rapidly heating at a high temperature, and then heating at a low heating speed to a medium temperature section. The step-by-step heating mode can avoid decomposition or side reactions (such as isomerization) of raw materials caused by rapid temperature rise. At the same time, the method can preliminarily remove water at a low temperature section, and promote esterification reaction at a medium temperature section, so as to ensure that acid and alcohol are fully contacted, and the esterification rate is improved. The alcohol flow rate is controlled, the flow rate can effectively remove water generated in the reaction, and the esterification reaction is promoted in a positive direction by alcohol reflux to maintain the concentration balance of the system. The reaction temperature is rapidly reached without boiling, the high-temperature reaction time is shortened, the energy consumption and side reactions are reduced, the slow cooling can reduce the crystallization or structural defects of the product caused by rapid temperature change, the product and water form emulsion in the subsequent neutralization and washing process is avoided, the layering efficiency and product purity are improved, and the stability of the plastic matrix is less affected when the product is used as a plasticizer. The diisononyl azelate synthesized by the method has a more integral molecular structure and uniform ester group distribution. When the product is used as a plasticizer, the product can interact with the plastic matrix segment through intermolecular hydrogen bonds, and the interfacial bonding force is enhanced, so that the elongation at break is improved while the modulus of the material is maintained. DETAILED DESCRIPTION

[0016] The application will be further described in detail below in combination with examples.

[0017] The azelaic acid (model number: JYS65163) used in the examples and comparative examples of the application is purchased from Wuhan Chongxin Biological Technology Co., Ltd.; the isononyl alcohol is purchased from Shandong Yukang Chemical Co., Ltd.; the PBAT (brand: TH801T) is purchased from Shanghai Changzheng Plastic Co., Ltd.

[0018] Examples 1-3 provide a diisononyl azelate and a preparation method and application thereof.

[0019] Example 1 A preparation method of diisononyl azelate comprises the following preparation steps: Step 1, azelaic acid and isononyl alcohol are sequentially put into a reaction kettle, vacuum is drawn after the feeding is completed, when the vacuum degree is-0.098 Mpa, the vacuum pump is closed and the nitrogen valve is opened, nitrogen is passed to normal pressure and heating is started, and the circulating water of the condensation system is opened, wherein the mass ratio of azelaic acid to isononyl alcohol is 12.2:23.6; Step 2, the reaction kettle is first heated to 110℃ at a speed of 3℃ / min, then heated to 130℃ at a speed of 1℃ / min, and kept at normal pressure for 3h, and then heated to 180℃ at a speed of 2℃ / min, the alcohol recovery pipeline is opened, and the valve is adjusted to make the alcohol recovery flow rate be 10L / h, so that the alcohol recovery is refluxed into the reaction kettle; Step 3, continue to heat to 185℃, and add tetrabutyl titanate, the temperature fluctuation range is ±1.5℃, and the addition amount of tetrabutyl titanate is 0.05% of the mass sum of azelaic acid and isononyl alcohol; Step 4, without boiling, the temperature is raised to 225℃ at a rate of 5℃ / min, and the reaction is maintained at a constant temperature of 0.1MPa, and the reaction is terminated when the acid value is 0.08; Step 5, the reactor is cooled to 85℃ at a rate of 1℃ / min, liquid alkali and deionized water are added, stirring at a speed of 300rpm for 20min, then standing for 20min, until the water ester is layered, and the water is removed, to obtain diisononyl azelate; wherein the amount of liquid alkali added is 12% of the theoretical yield of 32% sodium hydroxide solution; the amount of deionized water added is 10% of the mass of azelaic acid and isononyl alcohol.

[0020] Example 2 A method for preparing diisononyl azelate, comprising the following preparation steps: Step 1, azelaic acid and isononyl alcohol are sequentially added to the reactor, after the addition is completed, the vacuum pump is closed and the nitrogen valve is opened, the nitrogen is adjusted to normal pressure, the heating is started, and the circulating water of the condensing system is opened, wherein the mass ratio of azelaic acid to isononyl alcohol is 12.5:24.3; Step 2, the reactor is first heated to 115℃ at a rate of 4℃ / min, then heated to 135℃ at a rate of 1.5℃ / min, and kept at constant temperature under normal pressure for 4h, and then heated to 182℃ at a rate of 3℃ / min, the alcohol recovery pipeline is opened, and the valve is adjusted to make the alcohol recovery flow rate 12L / h, and the recovered alcohol is refluxed into the reactor; Step 3, continue to heat to 188℃, add titanium tetrabutoxide, the temperature fluctuation range is ±1.5℃, and the amount of titanium tetrabutoxide added is 0.08% of the mass sum of azelaic acid and isononyl alcohol; Step 4, without boiling, the temperature is raised to 227℃ at a rate of 7℃ / min, and the reaction is maintained at a constant temperature of 0.15MPa, and the reaction is terminated when the acid value is 0.08; Step 5, the reactor is cooled to 88℃ at a rate of 1.5℃ / min, liquid alkali and deionized water are added, stirring at a speed of 400rpm for 30min, then standing for 25min, until the water ester is layered, and the water is removed, to obtain diisononyl azelate; wherein the amount of liquid alkali added is 15% of the theoretical yield of 32% sodium hydroxide solution; the amount of deionized water added is 12% of the mass sum of azelaic acid and isononyl alcohol.

[0021] Example 3 A method for preparing diisononyl azelate, comprising the following preparation steps: Step 1, azelaic acid and isononyl alcohol were sequentially put into the reaction kettle, after the completion of feeding, vacuum was started, when the vacuum degree was-0.2Mpa, the vacuum pump was closed and the nitrogen valve was opened, nitrogen was passed to normal pressure and heating was started, and the circulating water of the condensing system was opened, wherein the mass ratio of azelaic acid and isononyl alcohol was 12.8:25.8; Step 2, the reaction kettle was first heated to 120℃ at a rate of 5℃ / min, then heated to 140℃ at a rate of 2℃ / min, and kept at constant pressure for 5h, and then heated to 185℃ at a rate of 4℃ / min, the alcohol recovery pipeline was opened, and the valve was adjusted to make the alcohol recovery flow rate 15L / h, and the recovered alcohol was refluxed into the reaction kettle; Step 3, continue to heat to 190℃, add tetrabutyl titanate, the temperature fluctuation range is ±1.5℃, the addition amount of tetrabutyl titanate is 0.1% of the mass sum of azelaic acid and isononyl alcohol; Step 4, without boiling, heat to 228℃ at a rate of 8℃ / min, and maintain 0.2MPa constant temperature reaction, when the acid value is 0.08, the reaction is terminated; Step 5, the reaction kettle was cooled to 90℃ at a rate of 2℃ / min, liquid alkali and deionized water were added, and the stirring speed was 500rpm, after stirring for 40min, it was placed for 30min, the water ester was separated, and the water was removed, and azelaic acid diisononyl ester was obtained; wherein the addition amount of liquid alkali is 18% of the theoretical yield of 32% concentration of sodium hydroxide solution; the addition amount of deionized water is 15% of the mass sum of azelaic acid and isononyl alcohol.

[0022] Comparative example 1 A preparation method of azelaic acid diisononyl ester, comprising the following preparation steps: Step 1, azelaic acid and isononyl alcohol were sequentially put into the reaction kettle, after the completion of feeding, vacuum was started, when the vacuum degree was-0.098Mpa, the vacuum pump was closed and the nitrogen valve was opened, nitrogen was passed to normal pressure and heating was started, and the circulating water of the condensing system was opened, wherein the mass ratio of azelaic acid and isononyl alcohol was 12.2:23.6; Step 2, the reaction kettle was first heated to 130℃ at a rate of 3℃ / min, then heated to 180℃ at a rate of 2℃ / min, and kept at constant pressure for 3h, and then heated to 180℃ at a rate of 2℃ / min, the alcohol recovery pipeline was opened, and the valve was adjusted to make the alcohol recovery flow rate 10L / h, and the recovered alcohol was refluxed into the reaction kettle; Step 3, continue to heat to 185℃, add tetrabutyl titanate, the temperature fluctuation range is ±1.5℃, the addition amount of tetrabutyl titanate is 0.05% of the mass sum of azelaic acid and isononyl alcohol; Step 4, without boiling, heat to 225℃ at a rate of 5℃ / min, and maintain 0.1MPa constant temperature reaction, when the acid value is 0.08, the reaction is terminated; Step 5, the reaction kettle is cooled to 85℃ at a cooling rate of 1℃ / min, liquid alkali and deionized water are added, stirring at a stirring speed of 300rpm for 20min, then standing for 20min, until the water ester is layered, and the water is removed, to obtain diisononyl azelate; wherein the amount of liquid alkali added is 12% of the theoretical yield of sodium hydroxide solution with a concentration of 32%; the amount of deionized water added is 10% of the mass sum of azelaic acid and isononyl alcohol.

[0023] Comparative Example 2 A preparation method of diisononyl azelate, comprising the following preparation steps: Step 1, azelaic acid and isononyl alcohol are sequentially put into a reaction kettle, after the completion of feeding, vacuum is started, when the vacuum degree is-0.098Mpa, the vacuum pump is closed and the nitrogen valve is opened, nitrogen is passed to normal pressure and heating is started, and the circulating water of the condensation system is opened, wherein the mass ratio of azelaic acid to isononyl alcohol is 12.2:23.6; Step 2, the reaction kettle is first heated to 130℃ at a heating rate of 1℃ / min, and then heated to 180℃ at a heating rate of 2℃ / min, the alcohol recovery pipeline is opened, and the valve is adjusted to make the alcohol recovery flow rate 10L / h, so that the recovered alcohol is refluxed into the reaction kettle; Step 3, continue to heat to 185℃, add tetrabutyl titanate, the temperature fluctuation range is ±1.5℃, and the amount of tetrabutyl titanate added is 0.05% of the mass sum of azelaic acid and isononyl alcohol; Step 4, under the condition of no boiling, heat to 225℃ at a heating rate of 5℃ / min, and maintain 0.1MPa constant temperature reaction, and the reaction is terminated when the acid value is 0.08; Step 5, the reaction kettle is cooled to 85℃ at a cooling rate of 1℃ / min, liquid alkali and deionized water are added, stirring at a stirring speed of 300rpm for 20min, then standing for 20min, until the water ester is layered, and the water is removed, to obtain diisononyl azelate; wherein the amount of liquid alkali added is 12% of the theoretical yield of sodium hydroxide solution with a concentration of 32%; the amount of deionized water added is 10% of the mass sum of azelaic acid and isononyl alcohol.

[0024] Comparative Example 3 A preparation method of diisononyl azelate, comprising the following preparation steps: Step 1, azelaic acid and isononyl alcohol are sequentially put into a reaction kettle, after the completion of feeding, vacuum is started, when the vacuum degree is-0.098Mpa, the vacuum pump is closed and the nitrogen valve is opened, nitrogen is passed to normal pressure and heating is started, and the circulating water of the condensation system is opened, wherein the mass ratio of azelaic acid to isononyl alcohol is 12.2:23.6; Step 2, first heat the reactor to 110℃ at a rate of 3℃ / min, then heat to 130℃ at a rate of 1℃ / min, maintain at normal pressure for 3h, continue to heat to 180℃ at a rate of 2℃ / min, open the alcohol recovery pipeline, adjust the valve to make the alcohol flow rate 5L / h, make the alcohol reflux into the reactor; Step 3, continue to heat to 185℃, add tetrabutyl titanate, the temperature fluctuation range is ±1.5℃, the addition amount of tetrabutyl titanate is 0.05% of the mass sum of azelaic acid and isononyl alcohol; Step 4, without boiling, heat to 225℃ at a rate of 5℃ / min, and maintain at 0.1MPa constant temperature reaction, terminate the reaction when the acid value is 0.08; Step 5, cool the reactor to 85℃ at a rate of 1℃ / min, add liquid alkali and deionized water, stir at a speed of 300rpm for 20min, then stand for 20min, separate the water ester layer, remove the water, and obtain diisononyl azelate; wherein the addition amount of liquid alkali is 12% of the theoretical yield of 32% sodium hydroxide solution; the addition amount of deionized water is 10% of the mass sum of azelaic acid and isononyl alcohol.

[0025] Comparative Example 4 A preparation method of diisononyl azelate, comprising the following preparation steps: Step 1, azelaic acid and isononyl alcohol are sequentially put into the reactor, after the feeding is completed, vacuum is drawn, when the vacuum degree is-0.098Mpa, the vacuum pump is closed and the nitrogen valve is opened, nitrogen is passed to normal pressure, heating is started, and the condensation system circulating water is opened, wherein the mass ratio of azelaic acid to isononyl alcohol is 12.2:23.6; Step 2, first heat the reactor to 110℃ at a rate of 3℃ / min, then heat to 130℃ at a rate of 1℃ / min, maintain at normal pressure for 3h, continue to heat to 180℃ at a rate of 2℃ / min, open the alcohol recovery pipeline, adjust the valve to make the alcohol flow rate 20L / h, make the alcohol reflux into the reactor; Step 3, continue to heat to 185℃, add tetrabutyl titanate, the temperature fluctuation range is ±1.5℃, the addition amount of tetrabutyl titanate is 0.05% of the mass sum of azelaic acid and isononyl alcohol; Step 4, without boiling, heat to 225℃ at a rate of 5℃ / min, and maintain at 0.1MPa constant temperature reaction, terminate the reaction when the acid value is 0.08; Step 5, the reaction kettle is cooled to 85℃ at a cooling rate of 1℃ / min, liquid alkali and deionized water are added, stirring at a stirring speed of 300rpm for 20min, then standing for 20min, until the water ester is layered, and the water is removed, to obtain diisononyl azelate; wherein the amount of liquid alkali added is 12% of the theoretical yield of a 32% sodium hydroxide solution; the amount of deionized water added is 10% of the mass sum of azelaic acid and isononyl alcohol.

[0026] Comparative Example 5 A method for preparing diisononyl azelate, comprising the following preparation steps: Step 1, azelaic acid and isononyl alcohol are sequentially put into a reaction kettle, after the completion of feeding, vacuum is started, when the vacuum degree is-0.098Mpa, the vacuum pump is closed and the nitrogen valve is opened, nitrogen is passed to normal pressure and heating is started, and the circulating water of the condensation system is opened, wherein the mass ratio of azelaic acid to isononyl alcohol is 12.2:23.6; Step 2, the reaction kettle is first heated to 110℃ at a rate of 3℃ / min, then heated to 130℃ at a rate of 1℃ / min, and kept at constant pressure for 3h, then heated to 180℃ at a rate of 2℃ / min, the alcohol recovery pipeline is opened, and the valve is adjusted to make the alcohol recovery flow rate 10L / h, so that the recovered alcohol flows back to the reaction kettle; Step 3, continue to heat to 185℃, add tetrabutyl titanate, the temperature fluctuation range is ±1.5℃, and the amount of tetrabutyl titanate added is 0.05% of the mass sum of azelaic acid and isononyl alcohol; Step 4, under the condition of no boiling, heat to 225℃ at a rate of 2℃ / min, and keep constant temperature at 0.1MPa, and the reaction is terminated when the acid value is 0.08; Step 5, the reaction kettle is cooled to 85℃ at a cooling rate of 1℃ / min, liquid alkali and deionized water are added, stirring at a stirring speed of 300rpm for 20min, then standing for 20min, until the water ester is layered, and the water is removed, to obtain diisononyl azelate; wherein the amount of liquid alkali added is 12% of the theoretical yield of a 32% sodium hydroxide solution; the amount of deionized water added is 10% of the mass sum of azelaic acid and isononyl alcohol.

[0027] Comparative Example 6 A method for preparing diisononyl azelate, comprising the following preparation steps: Step 1, azelaic acid and isononyl alcohol are sequentially put into a reaction kettle, after the completion of feeding, vacuum is started, when the vacuum degree is-0.098Mpa, the vacuum pump is closed and the nitrogen valve is opened, nitrogen is passed to normal pressure and heating is started, and the circulating water of the condensation system is opened, wherein the mass ratio of azelaic acid to isononyl alcohol is 12.2:23.6; Step 2, first increase the temperature of the reactor to 110°C at a rate of 3°C / min, then increase the temperature to 130°C at a rate of 1°C / min, maintain at normal pressure for 3h, continue to increase the temperature to 180°C at a rate of 2°C / min, open the alcohol recovery pipeline, adjust the valve to make the alcohol recovery flow rate 10L / h, make the alcohol recovery reflux into the reactor; Step 3, continue to increase the temperature to 185°C, add tetrabutyl titanate, the temperature fluctuation range is ±1.5°C, the addition amount of tetrabutyl titanate is 0.05% of the mass sum of azelaic acid and isononyl alcohol; Step 4, increase the temperature to 225°C at a rate of 5°C / min without boiling, maintain at 0.1MPa, when the acid value is 0.08, the reaction is terminated; Step 5, decrease the temperature of the reactor to 85°C at a rate of 5°C / min, add liquid alkali and deionized water, stir at a speed of 300rpm for 20min, then stand for 20min, separate the water ester layer, remove the water, and obtain diisononyl azelate; the addition amount of liquid alkali is 12% of the theoretical yield of sodium hydroxide solution with a concentration of 32%; the addition amount of deionized water is 10% of the mass sum of azelaic acid and isononyl alcohol.

[0028] Performance test By comparing the diisononyl azelate prepared in Comparative Examples 1-3 and Comparative Examples 1-6, the change of the material performance of PBAT as a plasticizer was further explored, and the performance indicators were compared with pure PBAT material, focusing on the analysis of three key parameters: tensile strength, breaking stress and elongation at break; Sample preparation: The diisononyl azelate prepared in Examples 1-3 and Comparative Examples 1-6 was mixed with PBAT matrix material as a plasticizer according to a mass ratio of 15%:85%; the obtained uniform mixture was added to the internal mixer, and the speed was 100rpm, the mixing was carried out at 135°C for 10min, and the blend was obtained; the obtained blend was added to the flat vulcanizing machine, and the vulcanization temperature was 140°C and the pressure was 18MPa, and the plasticized and reinforced PBAT polymer sample plate with a thickness of 1.3mm was obtained; The preparation method of pure PBAT material is as follows: PBAT matrix material is added to the internal mixer, the speed is 100rpm, the mixing is carried out at 135°C for 10min, and the blend is obtained; the obtained blend is added to the flat vulcanizing machine, and the vulcanization temperature is 140°C and the pressure is 18MPa, and the pure PBAT polymer sample plate with a thickness of 1.3mm is obtained; Tensile strength, breaking stress and elongation at break: refer to national standard GB / T 1040.1-2018 "Determination of tensile properties of plastics Part 1: General" for testing.

[0029] The specific test results are shown in Table 1.

[0030] Table 1 Plasticizing performance parameters of the diisononyl azelate prepared in Examples 1-3 and Comparative Examples 1-6

[0031] As can be seen from Table 1, the diisononyl azelate prepared in the application as a plasticizer can significantly improve the comprehensive mechanical properties of the PBAT plastic plate, and simultaneously improve the tensile strength, breaking stress and elongation at break. The modified plate exhibits excellent mechanical stability and toughness under the conditions of tensile, ultimate load impact and large deformation, and expands the applicability of PBAT in high-strength application scenarios.

[0032] The specific embodiments are merely an explanation of the application, and are not a limitation of the application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the specification, as long as the modifications are within the scope of the claims of the application.

Claims

1. A process for the preparation of diisononyl azelate, characterized in that, The preparation method comprises the following steps: Step 1, nonanoic acid and isononyl alcohol are sequentially put into a reaction kettle, after the completion of feeding, vacuum is extracted, when the vacuum degree is-0.098-0.2 MPa, the vacuum pump is closed and the nitrogen valve is opened, nitrogen is passed to normal pressure and heating is started, and the circulating water of the condensing system is opened; Step 2, the reaction kettle is heated to 130-140 DEG C, normal pressure is kept for 3-5 h, heating is continuously carried out to 180-185 DEG C, the alcohol recovery pipeline is opened, and the valve is adjusted to make the recovered alcohol reflux into the reaction kettle; Step 3, heating is continuously carried out to 185-190 DEG C, and a catalyst is added; Step 4, under the condition of no boiling, heating is carried out to 225-228 DEG C, and constant temperature reaction is kept at 0.1-0.2 MPa, when the acid value is less than 0.1, the reaction is terminated; Step 5, the reaction kettle is cooled to 85-90 DEG C, liquid alkali and deionized water are added, stirring is carried out for 20-40 min, and then standing is carried out for 20-30 min, after the water ester is separated, water is removed, and nonanoic acid diisononyl ester is obtained.

2. The method for preparing diisononyl azelate according to claim 1, characterized by, The mass ratio of nonanoic acid and isononyl alcohol in step 1 is 12-13:23-26.

3. The method of preparing diisononyl azelate according to claim 1, characterized in that, In step 2, stage heating is adopted, first heating is carried out to 110-120 DEG C at a speed of 3-5 DEG C / min, and then heating is carried out to 130-140 DEG C at a speed of 1-2 DEG C / min.

4. The method of preparing diisononyl azelate according to claim 1, characterized in that, The heating speed is 2-4 DEG C / min when heating is carried out to 180-185 DEG C in step 2.

5. The method of preparing diisononyl azelate according to claim 1, characterized in that, The alcohol recovery flow rate is 10-15 L / h in step 2.

6. The method of preparing diisononyl azelate according to claim 1, characterized in that, In step 3, the allowable temperature fluctuation range is ±1.5 DEG C during heating to 185-190 DEG C and adding the catalyst; the catalyst is one of titanium acid tetraisopropyl ester, titanium acid tetrabutyl ester and titanium acid tetraethyl ester.

7. The method of preparing diisononyl azelate according to claim 1, characterized in that, The heating speed is 5-8 DEG C / min when heating is carried out to 225-228 DEG C in step 4.

8. The method of preparing diisononyl azelate according to claim 1, characterized in that, The cooling speed is 1-2 DEG C / min when cooling is carried out to 85-90 DEG C in step 5.

9. The method of preparing diisononyl azelate according to claim 1, characterized in that, The rotation speed of the reaction kettle is 300-500 rpm.

10. The application of nonanoic acid diisononyl ester prepared by the preparation method in any one of claims 1-9 in plastic processing.

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