Acrylate and preparation method thereof

Abstract

The invention relates to the field of organic synthesis, and particularly discloses acrylate and a preparation method thereof. The structural formulas of the acrylate are shown as a formula I and a formula II, the formula I is # imgabs 0 #, the formula II is # imgabs 1 #, and R is H or CH3. According to the present invention, the acrylate with the structural formulas of the formula I and the formula II has characteristics of strong alkali tolerance, alkali saponification resistance, low permeability, small skin irritation and light taste, has characteristics of low volume shrinkage after light curing, almost no deformation, and high adhesion to the base material, and can be widely used in many occasions.

Description

Technical Field

[0001] The present invention relates to the field of organic synthesis, and more specifically, to an acrylate and a preparation method thereof. Background Art

[0002] Photocurable materials are special materials that use light energy to trigger chemical reactions, thereby achieving material curing. After being irradiated with a specific wavelength (such as ultraviolet light), the photosensitive components in this material will absorb light energy and trigger a chain reaction, causing the material to change from liquid or semi-solid to solid. It has the characteristics of fast curing speed, energy saving and environmental protection, strong adaptability, and high performance. It is widely used in the fields of 3D printing, coatings, inks, adhesives, etc. Photocurable materials usually include a large number of compounds containing double bonds, such as acrylates or methacrylates. These compounds can open double bonds under the action of light to form active free radicals, thereby initiating the curing process of the material. However, when acrylates or methacrylates are polymerized, the intermolecular forces are converted from hydrogen bonds or van der Waals forces to carbon-carbon single bonds, and the molecular volume is instantly reduced to a large extent. After curing, it is easy to deform, resulting in a decrease in adhesion and affecting the service life of the photocurable material.

[0003] Tetrahydrofurfuryl acrylate has a five-membered ring of tetrahydrofuran in its structure, so it has good compatibility with other chemicals, and has strong dissolution permeability to general plastics and a small volume shrinkage after solidification. In addition, its initial raw material is furfural, which can be extracted from various agricultural and sideline products, such as corn cobs, oats and wheat bran, sawdust, etc., and has good reproducibility and environmental protection, meeting the requirements of sustainable development. However, tetrahydrofuran acrylate has extremely strong permeability, so it is more irritating to the skin and has a certain taste. In addition, tetrahydrofuran acrylate also has the problem of poor alkali resistance, and is prone to saponification reaction with alkali, so it is often necessary to carry out redistillation in industrial mass production to obtain colorless or low-chroma tetrahydrofuran acrylate.

[0004] Another acrylate that is widely used in the light-curable ink industry is Cyclic Trimethylol-propane Formal Acrylate (CTFA, CAS No. 66492-51-1). CTFA is a monofunctional acrylate with the characteristics of low viscosity, low surface tension, low volatility, low odor, low shrinkage, good adhesion, high hardness, and good chemical resistance. This monomer has a high tolerance to alkali and is not easy to produce saponification reaction with alkali. It is widely used in coatings, plastics, metals, wood, inks, paper varnishes and other fields. However, Cyclic Trimethylol-propane Formal Acrylate still has high permeability and is highly irritating to the skin. Summary of the invention

[0005] In order to solve the above technical problems, the present application provides an acrylate and a preparation method thereof.

[0006] In the first aspect, the present application provides an acrylate, which adopts the following technical solution: An acrylate, the structural formula of the acrylate is shown in Formula I and Formula II, wherein Formula I is The formula II is Wherein R=H or CH3.

[0007] By adopting the above technical scheme, the (meth) acrylate of the present application structural formula I and formula II has a strong tolerance to alkali, is not easy to saponify with alkali, and can use a large amount of alkali to decolorize in the alkali washing process to obtain a finished product with low chroma, does not need to be distilled, and simplifies the production process. In addition, the five-membered ring and six-membered ring structure contained in the molecular structure of the two can suppress the shrinkage degree of the volume after solidification, so that it has a lower volume shrinkage rate and higher adhesion. Moreover, the tetrahydrofuran ring fragment contained in the molecular structure of the two can further improve the adhesion of acrylate or methacrylate to the substrate. At the same time, the acrylate or methacrylate of the present application structural formula I and formula II also has the characteristics of low permeability, low skin irritation and light taste, which greatly broadens the application scene of (meth) acrylate.

[0008] In a second aspect, the present application provides a method for preparing acrylic acid ester, which adopts the following technical scheme: A method for preparing an acrylic acid ester having a structural formula of Formula I comprises the following steps: First, furfural is hydrogenated to obtain tetrahydrofurfural, and then, under the protection of inert gas, tetrahydrofurfural and trimethylolpropane are azeotropically dehydrated under the action of an acid catalyst. When the reaction water output reaches the theoretical water output, tetrahydrofurfural trimethylolpropane is obtained. Subsequently, tetrahydrofurfural trimethylolpropane is azeotropically dehydrated with acrylic acid or methacrylic acid in the presence of oxygen and a polymerization inhibitor. When the reaction water output reaches the theoretical water output and the acid value changes by ≤1.0 mgKOH / g per hour, the reaction is stopped. After post-treatment, an acrylic ester with a structural formula of Formula I is obtained. The reaction formula of the process is as follows:

[0009] A method for preparing an acrylic acid ester having a structural formula of Formula I comprises the following steps: Under the protection of inert gas, furfural and trimethylolpropane are first azeotropically dehydrated under the action of an acid catalyst, and when the reaction water output reaches the theoretical water output, furfural trimethylolpropane is obtained, and then the furfural trimethylolpropane is hydrogenated under high pressure under the condition of palladium / carbon as a catalyst to obtain tetrahydrofurfural trimethylolpropane, and then tetrahydrofurfural trimethylolpropane is azeotropically dehydrated with acrylic acid or methacrylic acid in the presence of oxygen and a polymerization inhibitor, and the reaction is stopped when the reaction water output reaches the theoretical water output and the acid value changes by ≤1.0 mgKOH / g per hour, and then after post-treatment, an acrylic ester with the structural formula of formula I is obtained; the reaction formula of the process is as follows:

[0010] Preferably, the post-treatment is specifically as follows: firstly, an alkaline solution is used to remove excess acid in the system, and then an inhibitor is added to perform reduced pressure distillation to obtain an acrylate having a structural formula of Formula I.

[0011] Through the above technical scheme, the present application adopts two routes to synthesize the acrylic ester of the structural formula I, one of which is: furfural is selectively hydrogenated to only the unsaturated double bonds of the furan five-membered ring through the catalyst to obtain tetrahydrofurfural, and then the tetrahydrofurfural is mixed with trimethylolpropane, and an appropriate amount of p-toluenesulfonic acid is added as an acid catalyst, cyclohexane is added as a solvent, and under the protection of an inert gas, heating is performed for azeotropic dehydration, and when the reaction water output reaches the theoretical water output, the crude product of tetrahydrofurfural trimethylolpropane can be obtained. Then, at a temperature not higher than 60° C., tetrahydrofurfural trimethylolpropane and acrylic acid or methacrylic acid are mixed in a reaction bottle, 4-methoxyphenol is added as a polymerization inhibitor, cyclohexane is added as a solvent, and then an appropriate amount of air is introduced, and the temperature is raised for azeotropic dehydration. When the reaction water output reaches the theoretical water output and the acid value changes by ≤1.0 mgKOH / g per hour, the reaction is stopped, and then an aqueous sodium hydroxide solution is used to remove excess acid in the system, and then an appropriate amount of 4-methoxyphenol is added for reduced pressure distillation to remove and recover the solvent, thereby obtaining an acrylic acid ester with the structural formula of Formula I.

[0012] Another route is: firstly, furfural is directly subjected to a dehydration condensation reaction with trimethylolpropane to obtain furfural trimethylolpropane acetal, and the specific reaction process is the same as the first route, and then the furfural trimethylolpropane acetal is subjected to high pressure hydrogenation under the condition of palladium / carbon as a catalyst. Those skilled in the art can also select nickel as a catalyst according to common knowledge to obtain a crude tetrahydrofurfural trimethylolpropane acetal. Subsequently, an acrylate having a structural formula of formula I is prepared in the same manner as the first route.

[0013] When the raw material is acrylic acid, that is, R=H, the final acrylic ester obtained is tetrahydrofurfural trimethylolpropane acrylate; when the raw material is methacrylic acid, that is, R=CH3, the final acrylic ester obtained is tetrahydrofurfural trimethylolpropane methacrylate.

[0014] The above two pathways adopted in this application both use furfural as raw material. Furfural mainly comes from plant materials rich in pentosans, such as corn cobs, oat hulls, cottonseed hulls, bagasse, rice husks, etc. It has good renewability and environmental protection, and meets the requirements of sustainable development.

[0015] A method for preparing an acrylic acid ester having a structural formula of formula II comprises the following steps: Under the protection of inert gas, tetrahydrofuran-3-acetal and trimethylolpropane are first subjected to azeotropic dehydration under the action of an acid catalyst, and when the reaction water output reaches the theoretical water output, tetrahydrofuran-3-acetal trimethylolpropane is obtained, and then tetrahydrofuran-3-acetal trimethylolpropane is subjected to azeotropic dehydration with acrylic acid or methacrylic acid in the presence of oxygen and a polymerization inhibitor, and the reaction is stopped when the reaction water output reaches the theoretical water output and the acid value changes by ≤1.0 mgKOH / g per hour, and then after post-treatment, an acrylic acid ester with a structural formula of formula II is obtained; the reaction formula of the process is as follows:

[0016] Preferably, the post-treatment is specifically as follows: firstly, an alkaline solution is used to remove excess acid in the system, and then an inhibitor is added to perform reduced pressure distillation to obtain an acrylate having a structural formula of Formula II.

[0017] Through the above technical solution, the acrylic acid ester with the structural formula of formula II is an isomer of formula I, and has the same excellent properties as formula I. The synthesis method of the acrylic ester with the structural formula of formula II of the present application is as follows: tetrahydrofuran-3-acetal is used as the starting reaction raw material and mixed with trimethylolpropane, and an appropriate amount of p-toluenesulfonic acid is added as an acid catalyst, cyclohexane is added as a solvent, and heated under the protection of an inert gas for azeotropic dehydration. When the reaction water output reaches the theoretical water output, a crude tetrahydrofurfural trimethylolpropane product can be obtained. The crude tetrahydrofurfural trimethylolpropane product is mixed with acrylic acid or methacrylic acid in a reaction bottle at a temperature not higher than 60° C., 4-methoxyphenol is added as a polymerization inhibitor, cyclohexane is added as a solvent, and then an appropriate amount of air is introduced, and the temperature is raised for azeotropic dehydration. When the reaction reaches the theoretical water output and the acid value changes by ≤1.0 mgKOH / g per hour, the reaction is stopped, and then an aqueous sodium hydroxide solution is used to remove excess acid in the system, and then an appropriate amount of 4-methoxyphenol is added to carry out reduced pressure distillation to remove and recover the solvent, thereby obtaining an acrylic ester with the structural formula of formula II.

[0018] When the raw material is acrylic acid, that is, R=H, the final acrylic ester obtained is tetrahydrofuran-3-acetal trimethylolpropane acrylate; when the raw material is methacrylic acid, that is, R=CH3, the final acrylic ester obtained is tetrahydrofuran-3-acetal trimethylolpropane methacrylate.

[0019] In summary, this application has the following beneficial technical effects: 1. The acrylic acid esters of the structural formulas I and II of the present application have strong tolerance to alkali and are not easy to undergo saponification reaction with alkali. In the alkali washing process of the post-treatment, a large amount of alkali can be used for decolorization to obtain a low-color finished product without the need for distillation, thereby simplifying the production process; 2. The acrylates of the structural formulas of Formula I and Formula II of the present application have a low volume shrinkage rate after curing, almost no deformation, and high adhesion to the substrate; 3. The acrylates of formula I and formula II of the present application have the characteristics of low permeability, low skin irritation and light taste, and can be widely used in many occasions; 4. The acrylic ester of the present application with the structural formula I is prepared from furfural, a bio-based raw material, and has good renewability and environmental protection, meeting the requirements of sustainable development. DETAILED DESCRIPTION

[0020] The present application is further described in detail below with reference to the embodiments.

[0021] The raw materials used in this application are all commercially available products, specifically: Furfural, CAS No. 98-01-1, purchased from Shandong Qiyun Chemical Technology Co., Ltd.; Trimethylolpropane, CAS No. 77-99-6, purchased from Shandong Tonglan Chemical Co., Ltd.; p-Toluenesulfonic acid, CAS No. 104-15-4, purchased from Jinan Yucai Chemical Co., Ltd.; Acrylic acid, CAS No. 79-10-7, purchased from Shandong Luying Chemical Co., Ltd.; 4-Methoxyphenol, CAS No. 150-76-5, was purchased from Panhua Chemical (Shanghai) Co., Ltd., model inhibitor MEHQ; cyclohexane, CAS No. 110-82-7, was purchased from Shandong Feihong New Materials Co., Ltd.

[0022] In the specific embodiments of the present application, the preparation of acrylate is described by taking acrylic acid as a raw material as an example. Those skilled in the art only need to replace acrylic acid with methacrylic acid to obtain methacrylate.

[0023] In the specific embodiments of the present application, only one route for preparing the acrylic ester of structural formula I is used for illustration. Those skilled in the art can conventionally select the timing of hydrogenation and adopt another method to prepare the acrylic ester of structural formula I.

[0024] Example 1 A method for preparing tetrahydrofurfural trimethylolpropane acrylate comprises the following steps: 1.5 mol of furfural is hydrogenated to obtain tetrahydrofurfural, and then the tetrahydrofurfural is mixed with 1.5 mol of trimethylolpropane, and 0.0375 mol of p-toluenesulfonic acid and 205 g of cyclohexane are added to the system, and nitrogen is introduced at a flow rate of 20 mL / min, and the temperature is raised to 68° C. and azeotropically dehydrated for 7 hours, and the reaction is stopped when the reaction water output reaches 33 g (satisfying the requirement of ≥29.7 g) to obtain a crude tetrahydrofurfural trimethylolpropane; Subsequently, at a temperature not higher than 60 ℃, crude tetrahydrofurfural trimethylolpropane and 1.575mol acrylic acid are mixed, 0.338g of 4-methoxyphenol and 30g of cyclohexane are added to the system simultaneously, and air is passed through with a flow velocity of 60mL / min, and after being heated to 75 ℃ of azeotropic dehydration for 15 hours, the reaction water yield reaches 28g (satisfying the requirement of ≥27g) and the acid value changes by ≤1.0mgKOH / g per hour, and the reaction is stopped, and 75g of sodium hydroxide aqueous solution whose concentration is 15wt% is added to the system to remove excessive acid, and then 0.05g of 4-methoxyphenol is added to carry out underpressure distillation, and finally 357.21g of tetrahydrofurfural trimethylolpropane acrylate is obtained, and the yield is 88.28%.

[0025] Example 2 A method for preparing tetrahydrofuran-3-acetal trimethylolpropane acrylate comprises the following steps: 1.5 mol of tetrahydrofuran-3-acetal and 1.5 mol of trimethylolpropane were mixed, and 0.0375 mol of p-toluenesulfonic acid and 205 g of cyclohexane were added to the system, and nitrogen was introduced at a flow rate of 20 mL / min. After heating to 68° C. and azeotropic dehydration for 6 hours, the reaction was stopped when the reaction water output reached 32.5 g (satisfying the requirement of ≥29.7 g) to obtain crude tetrahydrofuran-3-acetal trimethylolpropane; Subsequently, at a temperature not higher than 60° C., the crude tetrahydrofuran-3-acetal trimethylolpropane and 1.575 mol of acrylic acid were mixed, 0.338 g of 4-methoxyphenol and 30 g of cyclohexane were added to the system, and air was introduced at a flow rate of 60 mL / min. After being heated to 74° C. for azeotropic dehydration for 15 hours, the reaction water yield reached 27.5 g (satisfying the requirement of ≥27 g) and the acid value changed by ≤1.0 mgKOH / g per hour. The reaction was stopped, 75 g of a 15 wt % aqueous sodium hydroxide solution was added to the system to remove excess acid, and then 0.05 g of 4-methoxyphenol was added for reduced pressure distillation to finally obtain 353.91 g of tetrahydrofuran-3-acetal trimethylolpropane acrylate in a yield of 87.4%.

[0026] Performance Testing 1. The acrylate prepared in the above embodiment was tested for relevant properties. The specific test results are shown in Table 1.

[0027] 2. The acrylates, tetrahydrofuran acrylate (THFA) and cyclotrimethylolpropane methyl acrylate (CTFA) prepared in the above examples were subjected to plastic material permeability tests, sodium hydroxide tolerance tests and taste tests. The specific test results are shown in Tables 2-4; wherein tetrahydrofuran acrylate (THFA) and cyclotrimethylolpropane methyl acrylate (CTFA) are both products of Shanxi Jinchuan Synthetic Materials Co., Ltd.; The test method of plastic material permeability is as follows: take one drop of tetrahydrofuran acrylate (THFA), cyclotrimethylolpropane formal acrylate (CTFA) and the acrylate prepared in the above embodiment and drop them on different types of plastic sheets, and then wipe the sheet with paper after 1 hour or 24 hours to observe the surface condition of the sheet; The test method for sodium hydroxide tolerance is as follows: 50 g of tetrahydrofuran acrylate (THFA), cyclotrimethylolpropane formal acrylate (CTFA) and the acrylate prepared in the above embodiment are respectively mixed with 50 g of toluene, and after being completely dissolved, they are respectively added to a 250 mL separatory funnel, and then 20 g of 20 wt % sodium hydroxide is added to each separatory funnel, and the mixture is vigorously mixed and shaken for 5 minutes, and then allowed to stand for 2 hours, and the pH value of the water layer is respectively tested. The pH value of the water layer ≤7.0 indicates that the acrylic acid undergoes saponification reaction with the sodium hydroxide, and the pH value of the water layer >7.0 indicates that the acrylic acid has strong tolerance to sodium hydroxide; The test method of the taste test is: take equal amounts of tetrahydrofuran acrylate (THFA), cyclotrimethylolpropane formal acrylate (CTFA) and the acrylate prepared in the above examples, and smell them directly with the nose.

[0028] 3. The volume shrinkage and adhesion of the acrylates, tetrahydrofuran acrylate (THFA) and cyclotrimethylolpropane formal acrylate (CTFA) prepared in the above embodiments were measured after curing, and the test results are shown in Table 5; wherein, the method for measuring the volume shrinkage is as follows: 20 g of the acrylates prepared in Examples 1-2 were taken as samples, and then 0.4 g of TPO (CAS No. 75980-60-8, the substance is specifically (2,4,6-trimethylbenzoyl) diphenylphosphine oxide, which is a high-efficiency photoinitiator, purchased from Gansu Qingyu Company) was added to each sample, and then irradiated with 395 nm LED ultraviolet light (10 W) for 5 minutes, and then allowed to stand for 30 minutes, and then the volume shrinkage before and after light curing was measured using 20° C. water and a 100 mL specific gravity cup; The adhesion test method is as follows: the acrylate prepared in Example 1-2 is mixed with AgiSyn 230A2 (a trade name produced by Costron, Germany, and the substance is specifically aliphatic hexafunctional polyurethane) and TPO, and the mass percentage of acrylate, AgiSyn 230A2 and TPO is 70:30:3. After stirring evenly, apply it on the ABS+PC board with a 3c coating rod and coat it with 100W / cm 2 After drying with UV LED 365nm and standing for half an hour, refer to the cross-cut method in GB / T 9286-2021 and measure with a cross-cut knife and 3M 600 adhesion test tape.

[0029] Table 1 Acrylate test results project Example 1 Example 2 Gas Spectrum Purity (GC, %) 84.66 83.32 MEHQ content (ppm) 240 245 Viscosity(cps) 240 216 Acid value (mgKOH / g) 0.08 0.09 Chroma (α) 20 28 Specific gravity (g / mL) 1.125 1.124 Refractive index (nD) 1.4709 1.4708 Turbidity(NYU) 0 0 Table 2 Plastic material permeability test results Table 3 Sodium hydroxide tolerance test results project pH value of water layer Tolerance Tetrahydrofuran acrylate 6-7 Intolerance Cyclotrimethylolpropane formal acrylate 13 Tolerance Example 1 13 Tolerance Example 2 13 Tolerance Table 4 Taste test results project odor Tetrahydrofuran acrylate Pungent smell Cyclotrimethylolpropane formal acrylate light Example 1 light Example 2 light Table 5 Volume shrinkage and adhesion test results project Volume shrinkage (%) Adhesion(MPa) Tetrahydrofuran acrylate 6.24 5B Cyclotrimethylolpropane formal acrylate 10.55 5B Example 1 9.95 5B Example 2 9.96 5B Data Analysis: As can be seen from Tables 1-5, the yield and purity of the acrylate obtained in Examples 1-2 of the present application are high, there are fewer by-products, and the tolerance to alkali is strong, it is not easy to undergo saponification reaction with alkali, and a large amount of alkali can be used for decolorization in the post-processing process of the preparation to obtain a low-chroma product without distillation. And the permeability of the acrylate obtained in Examples 1-2 of the present application to different plastic materials is lower than that of tetrahydrofuran acrylate and cyclotrimethylolpropane formal acrylate, and the irritation to the skin is low, and the taste is small. Moreover, the acrylate obtained in Examples 1-2 of the present application has a small volume shrinkage rate after photocuring, almost no deformation occurs, and the adhesion to the substrate is high, and it can be widely used in many occasions. In addition, the acrylate obtained in Example 1 of the present application is obtained via a bio-based raw material such as furfural, has good renewability and environmental protection, and meets the requirements of sustainable development.

[0030] In summary, the present application combines the advantages of tetrahydrofuran acrylate and cyclotrimethylolpropane formal acrylate to produce an acrylate with light taste, low irritation, strong alkali resistance, low volume shrinkage after curing, and high adhesion. In addition, the acrylate with the structural formula of formula I is made from a bio-based raw material such as furfural, and has good renewability and environmental protection, meeting the requirements of sustainable development.

[0031] The embodiments of this specific implementation method are all preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. Therefore, all equivalent changes made based on the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. An acrylate, characterized in that: The structural formula of the acrylic ester is shown in Formula I and Formula II, wherein Formula I is The formula II is Wherein R=H or CH3.

2. A method for preparing the acrylic acid ester according to claim 1, characterized in that: The preparation method of the acrylic acid ester having the structural formula of Formula I comprises the following steps: First, furfural is hydrogenated to obtain tetrahydrofurfural, and then, under the protection of inert gas, tetrahydrofurfural and trimethylolpropane are azeotropically dehydrated under the action of an acid catalyst. When the reaction water output reaches the theoretical water output, tetrahydrofurfural trimethylolpropane is obtained. Subsequently, tetrahydrofurfural trimethylolpropane is azeotropically dehydrated with acrylic acid or methacrylic acid in the presence of oxygen and a polymerization inhibitor. When the reaction water output reaches the theoretical water output and the acid value changes by ≤1.0 mgKOH / g per hour, the reaction is stopped. After post-treatment, an acrylic ester with a structural formula of Formula I is obtained. The reaction formula of the process is as follows:

3. A method for preparing the acrylic ester according to claim 1, characterized in that: The preparation method of the acrylic acid ester having the structural formula of Formula I comprises the following steps: Under the protection of inert gas, furfural and trimethylolpropane are first azeotropically dehydrated under the action of an acid catalyst, and when the reaction water output reaches the theoretical water output, furfural trimethylolpropane is obtained, and then the furfural trimethylolpropane is hydrogenated under high pressure under the condition of palladium / carbon as a catalyst to obtain tetrahydrofurfural trimethylolpropane, and then tetrahydrofurfural trimethylolpropane is azeotropically dehydrated with acrylic acid or methacrylic acid in the presence of oxygen and a polymerization inhibitor, and the reaction is stopped when the reaction water output reaches the theoretical water output and the acid value changes by ≤1.0 mgKOH / g per hour, and then after post-treatment, an acrylic ester with the structural formula of formula I is obtained; the reaction formula of the process is as follows:

4. The method for preparing an acrylic ester according to claim 2 or 3, characterized in that: The post-treatment is specifically as follows: firstly, an alkaline solution is used to remove excess acid in the system, and then an inhibitor is added to perform reduced pressure distillation to obtain an acrylic acid ester having a structural formula of Formula I.

5. A method for preparing the acrylic ester according to claim 1, characterized in that: The preparation method of the acrylic acid ester having the structural formula II comprises the following steps: Under the protection of inert gas, tetrahydrofuran-3-acetal and trimethylolpropane are first subjected to azeotropic dehydration under the action of an acid catalyst, and when the reaction water output reaches the theoretical water output, tetrahydrofuran-3-acetal trimethylolpropane is obtained, and then tetrahydrofuran-3-acetal trimethylolpropane is subjected to azeotropic dehydration with acrylic acid or methacrylic acid in the presence of oxygen and a polymerization inhibitor, and the reaction is stopped when the reaction water output reaches the theoretical water output and the acid value changes by ≤1.0 mgKOH / g per hour, and then after post-treatment, an acrylic acid ester with a structural formula of formula II is obtained; the reaction formula of the process is as follows:

6. The method for preparing an acrylic ester according to claim 5, characterized in that: The post-treatment is specifically as follows: firstly, an alkaline solution is used to remove excess acid in the system, and then a polymerization inhibitor is added to perform reduced pressure distillation to obtain an acrylate having a structural formula of Formula II.

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