Process for the continuous production of (meth)acrylic polyol esters

Abstract

The application discloses a kind of continuous production (methyl) polyol methacrylate method, to provide the continuous production method of (methyl) polyol methacrylate of esterification reaction rate fast, raw material conversion rate high, target product selectivity high, product purity high;The method is by using non-traditional reaction rectification equipment, using solid acid catalyst and packing mixed packing rectification column catalytic reaction, under the condition of reduced pressure continuous reaction rectification, overhead discharge recovery low boiling point reaction raw material or obtain high-purity (methyl) polyol methacrylate product, after the discharge of column, high-purity (methyl) polyol methacrylate product or raw material is obtained by reduced pressure rectification;Belong to fine chemical technology field.

Description

Technical Field

[0001] This invention belongs to the field of continuous production of (meth)acrylic acid polyol esters, specifically relating to a method for continuous production of (meth)acrylic acid polyol esters, and the method for continuously obtaining (meth)acrylic acid polyol ester products. Background Technology

[0002] (Meth)acrylate polyol esters are an important chemical raw material. Due to the presence of a series of functional groups in their molecules, including active C=C, -OH, carboxyl derivatives, and long-side ester chain monomers, they can be used as polymerizing monomers to form various polymers through homopolymerization and copolymerization. Their structure determines that the polymers produced possess excellent weather resistance, UV resistance, water resistance, and heat resistance, making them mainly used in a wide range of fields such as polymerization modification, adhesives, inks, and coatings.

[0003] Currently, the main methods for preparing (meth)acrylic acid polyol esters, both domestically and internationally, include direct esterification and transesterification. Direct esterification is further divided into solvent esterification and melt esterification. Solvent esterification involves adding an organic solvent to the reaction system as a dehydrating agent, allowing it to form an azeotrope with the water generated during the reaction, continuously carrying the water out of the system and promoting the reaction towards the product. Catalysts and polymerization inhibitors are often added to the reaction system. This method has advantages such as fast reaction rate, high selectivity, and easy removal of generated water. However, it requires the addition of toxic organic solvents such as toluene as dehydrating agents, making subsequent product purification difficult. Melt esterification is a synthesis method that does not add a dehydrating agent to the direct esterification reaction. Compared with other methods, this method can reduce the amount of catalyst and polymerization inhibitor used while shortening the reaction time, obtaining higher yields and purer products. From the perspectives of yield, product purity, and economy, melt esterification is superior. The transesterification method involves exchanging lower (meth)acrylate polyol esters with higher polyols to produce higher (meth)acrylate polyol esters. In this method, the methanol produced after transesterification forms a low-boiling-point azeotrope with the lower (meth)acrylate polyol ester. Although the azeotrope can carry methanol out of the reaction system and promote the forward reaction, it is difficult to separate methanol from the azeotrope afterward, and a lower (meth)acrylate polyol ester with a stoichiometric ratio of several times is required during the reaction.

[0004] CN101891613A discloses a method for preparing hydroxyethyl methacrylate: a flask equipped with a stirrer, thermometer, and reflux condenser is placed in a water bath, and ferric oxide is added as a catalyst, hydroquinone as a polymerization inhibitor, and methacrylic acid. The water bath is heated to 80-85°C, and the air in the reaction flask is replaced with nitrogen. After the ferric oxide is completely dissolved in the methacrylic acid, ethylene oxide is introduced and the gas is introduced for 4 hours. After the gas is introduced, the reaction continues for 1 hour. Then the reactants are transferred to a criterion distillation flask, and an appropriate amount of hydroquinone is added for vacuum distillation. The fraction collected at 82-85°C is the finished product. This method for continuous production of hydroxyethyl methacrylate carries the risk of explosion if the air is not completely removed.

[0005] CN100349852C discloses a method for preparing (meth)acrylic acid higher fatty polyol esters. In the presence of at least one polymerization inhibitor and azeotropic agent, (meth)acrylic acid and higher fatty polyols (dodecyl polyols or higher) are used as raw materials, and the (meth)acrylic acid higher fatty polyol esters are directly synthesized by esterification under the action of an acidic catalyst. After the esterification reaction, the reaction product undergoes post-treatment, followed by vacuum distillation to remove excess azeotropic agent and water. The product purity is greater than 98%, acidity is less than 0.03%, and color is less than 100 (APHA). The method provided by this invention is simple to operate, has a high yield, and produces high-quality products, making it suitable for industrial production. However, this method consumes a large amount of azeotropic agent during industrial production. Toluene and other similar agents are commonly used industrially, which can lead to difficulties in subsequent separation and impurities in the product.

[0006] CN107056613A discloses a method for preparing low-carbon polyol esters of acrylic acid from coal pyrolysis gas, comprising the following steps: cooling high-temperature coal pyrolysis gas through an oil-gas separation heat exchanger; removing dust solids from the coal pyrolysis gas after oil-gas separation; removing sulfur and oxygen impurities from the dried tail gas; further purifying the deoxygenated and desulfurized coal pyrolysis gas to remove hydrogen and methane gas, obtaining purified CO gas; removing moisture from the dust-removed tail gas; pressurizing the dried purified CO gas to the reaction pressure; using the pressurized CO gas as a carbonylation feedstock, reacting it with acetylene and low-carbon polyols in a reactor via a catalyst to generate low-carbon polyol esters of acrylic acid. This method utilizes a large amount of carbon monoxide gas from the coal pyrolysis gas to obtain low-carbon polyol ester products of acrylic acid. However, the production process of this method is overly complex, and subsequent product separation and purification are difficult.

[0007] CN108586237A discloses a method for preparing neopentyl glycol dimethacrylate. In the presence of a catalyst, p-toluenesulfonic acid, and an azeotropic dehydrating agent, neopentyl glycol and methacrylic acid are reacted at 78–92°C for 4–7 hours to synthesize neopentyl glycol dimethacrylate. The molar ratio of methacrylic acid to neopentyl glycol is 2.15:1. The amount of hexane as the azeotropic dehydrating agent is 45% of the total mass of the reactants, the catalyst is 4% of the total mass of the reactants, and the phenothiazine as the polymerization inhibitor is 0.1% of the total mass of the reactants. This method uses a large amount of azeotropic agent in the production of neopentyl glycol dimethacrylate, and the subsequent separation of the dehydrating agent is difficult.

[0008] Most published papers and patents on the preparation of (meth)acrylate polyol esters involve the intermittent reaction of (meth)acrylate and the corresponding polyol under the combined action of a dehydrating agent, catalyst, and polymerization inhibitor. This method consumes a significant amount of catalyst and polymerization inhibitor, and the dehydrating agent used is typically a toxic organic reagent such as toluene, leading to difficulties in subsequent separation and resulting in impure (meth)acrylate polyol esters. Currently, there are few methods for continuous production of (meth)acrylate polyol esters because continuous production suffers from unstable catalyst activity and an unstable reaction process, hence the limited reports on continuous production methods. Summary of the Invention

[0009] The present invention aims to provide a method for the continuous production of (meth)acrylic acid polyol esters with high raw material conversion rate, high target product selectivity, fast reaction efficiency, high product purity.

[0010] This invention discloses a method for continuous production of (meth)acrylate polyol esters, comprising the following steps:

[0011] Pretreatment: The raw material is preheated, the polymerization inhibitor is added to the raw material to dissolve, and stirred evenly. The solid acid catalyst and packing material are mixed evenly and then packed into the distillation column.

[0012] reaction:

[0013] The corresponding (meth)acrylic acid polyol esters are produced using polyols and (meth)acrylic acid as raw materials; or polyols and (meth)acrylic acid low carbon alcohol esters as raw materials; or (meth)acrylic acid polyol monoesters and (meth)acrylic acid as raw materials.

[0014] The reaction process utilizes non-traditional reactive distillation equipment, and the reactive distillation esterification reaction is carried out by controlling conditions such as feed rate, reaction temperature, system pressure, air volume and reflux ratio.

[0015] Post-processing: The condensate at the top of the column is subjected to vacuum distillation to remove water or low-boiling-point products. The remaining distillate is the desired product or unreacted raw material. If it is raw material, it is returned to continue the reaction. If it is product, it can be collected. The liquid collected in the bottom of the column is subjected to vacuum distillation to separate the raw material or product. If it is raw material, it is returned to continue the reaction. If it is product, it can be collected.

[0016] Furthermore, in the above-described continuous production method of (meth)acrylic acid polyol esters, the (meth)acrylic acid is acrylic acid or methacrylic acid.

[0017] Furthermore, in the above-mentioned continuous production method of (meth)acrylate polyol esters, the polyol is ethylene glycol, polyethylene glycol, propylene glycol, glycerol, pentaerythritol, or sorbitol.

[0018] Furthermore, in the above-mentioned continuous production method of (meth)acrylic acid polyol esters, the polyol feed rate is 1-100 kg / h.

[0019] Furthermore, in the above-mentioned continuous production method of (meth)acrylate polyol esters, the polymerization inhibitor is one or more combinations of hydroquinone, p-hydroxyanisole, phenothiazine, diethylhydroxylamine, trinitrobenzene, m-dinitrobenzene, m-nitrochlorobenzene, nitrobenzene, sodium nitrite, and CuSO4 / NaHSO4, and its dosage is 0.05% to 2% of the raw material mass.

[0020] Furthermore, in the above-mentioned continuous production method of (meth)acrylic acid polyol esters, the air flow rate through the reboiler is 5-100 L / h.

[0021] Furthermore, in the above-mentioned continuous production method of (meth)acrylic acid polyol esters, the solid acid catalyst is packed into the distillation column, and the ratio of V (solid acid):V (packing material) is 1:100 to 10:1.

[0022] Furthermore, in the above-mentioned continuous production method of (meth)acrylic acid polyol esters, the non-traditional reactive distillation equipment relies on a heated distillation column to provide heat for the esterification reaction, the reboiler is not heated, the pressure of the reactive distillation system is 5-100 kPa, and the temperature of the distillation column is 60-240°C.

[0023] Furthermore, in the above-mentioned continuous production method of (meth)acrylic acid polyol esters, the reflux ratio at the top of the reactive distillation equipment is 10:1 to 10:10.

[0024] Furthermore, in the above-mentioned continuous production method of (meth)acrylate polyol esters, (meth)acrylate alcohol esters with C4 to C6 carbon atoms are condensed at the top of the column, while (meth)acrylate alcohol esters with more than C7 carbon atoms are collected at the bottom of the column.

[0025] The continuous production method for (meth)acrylate polyol esters described in this invention has the following technical advantages compared with existing methods:

[0026] (1) The reaction uses solid acid as a catalyst. The catalyst and packing are uniformly mixed and packed into a distillation column, avoiding the catalyst separation step required by traditional catalyst post-processing.

[0027] (2) The melt esterification method is adopted, which does not require the addition of toxic water-removing agents such as toluene, and high-purity products can be easily obtained in the future.

[0028] (3) The molten esterification reaction is carried out under negative pressure, which promptly removes the low-boiling-point substances generated by the reaction from the system, promotes the forward reaction, and improves the conversion rate of raw materials.

[0029] (4) By adding reactants in a timely manner, transferring the condensate at the top of the tower and the liquid collected in the bottom of the tower, continuous production can be achieved.

[0030] (5) The technical solution provided by the present invention introduces air into the reaction process, which effectively increases the contact time between the raw materials and the solid acid catalyst, improves the catalytic efficiency, and the air, together with the polymerization inhibitor, enhances the polymerization inhibition effect.

[0031] (6) The technical solution provided by the present invention effectively controls the polymerization of unsaturated substances in the reaction process by regulating the temperature of the distillation column of the reaction distillation equipment, thereby improving the reaction efficiency. Attached Figure Description

[0032] Figure 1 This is the content detection spectrum of 4-(meth)acrylate hydroxybutyl ester in Example 1 of the present invention.

[0033] Figure 2 This is a spectrum of the mixture composition at the start of the reaction in Example 2 of the present invention.

[0034] Figure 3 This is a spectrum of the composition of the mixture after reaction in Example 2 of the present invention.

[0035] Figure 4 This is the content detection spectrum of butylene di(meth)acrylate in Example 2 of the present invention.

[0036] Figure 5 This is the detection spectrum of neopentyl glycol di(meth)acrylate in Example 3 of the present invention.

[0037] Figure 6 This is the content detection spectrum of ethylene glycol di(meth)acrylate in Example 4 of the present invention.

[0038] Figure 7 This is a structural diagram of the non-traditional reactive distillation equipment used in this invention;

[0039] Figure 8 This is a structural diagram of the non-traditional reactive distillation equipment used in this invention;

[0040] Figure 9 This is a control block diagram of the non-traditional reactive distillation equipment used in this invention. Detailed Implementation

[0041] The claims of the present invention will be further described in detail below with reference to specific embodiments, but this does not constitute any limitation on the present invention.

[0042] Example 1

[0043] This embodiment provides a continuous production method for 4-(meth)acrylate hydroxybutyl ester.

[0044] The packing material was uniformly packed with a ratio of V (perfluorosulfonic acid ion exchange resin):V (θ-ring packing) = 1:10. Using (meth)acrylic acid and 1,4-butanediol as raw materials, 1% phenothiazine was dissolved in the raw materials by weight. The (meth)acrylic acid and 1,4-butanediol were preheated to 90°C. The reaction section of the distillation column in the reactive distillation equipment was controlled at 90°C, the top condensing temperature at 13°C, the reflux ratio at 10:5, the system pressure at 80 kPa, and 20 L / h of air was introduced into the reboiler. The feed rate of 1,4-butanediol was controlled at 5 kg / h at the top inlet and 10 kg / h at the bottom inlet of (meth)acrylic acid. Quantitative analysis of the materials before and after the reaction was performed by gas chromatography, yielding a 98% conversion rate of 1,4-butanediol.

[0045] The condensate from the top of the column is transferred to a vacuum distillation unit. The condensate is a mixed solution of water from the esterification reaction and unreacted (meth)acrylic acid. The vacuum distillation system is controlled at 4–5 kPa and 60–65 °C. The water from the esterification reaction is distilled off, and the remaining liquid is (meth)acrylic acid. This (meth)acrylic acid is added to the lower feed inlet storage tank to continue its reaction. The bottom liquid is then transferred to a vacuum rectification unit. The bottom liquid is a mixed solution of 4-(meth)acrylic acid hydroxybutyl ester and phenothiazine. The vacuum rectification system is controlled at 2–3 kPa and 110–115 °C to obtain 4-(meth)acrylic acid hydroxybutyl ester. Figure 1 As shown in the GC spectrum, the hydroxybutyl 4-(meth)acrylate obtained by distillation has a content of 99.01%.

[0046] Example 2

[0047] This embodiment provides a continuous production method for butylene di(meth)acrylate.

[0048] The filler is V(Al2O3 / SO4) 2-The packing ratio of 4-hydroxybutyl 4-methacrylate (4-hydroxybutyl methacrylate) was uniformly packed with a ratio of V(θ ring packing) = 1:10. 0.5% polymerization inhibitor was dissolved in the raw materials, and the ratio of m(p-hydroxyanisole) to m(hydroquinone) was 1:1. The 4-hydroxybutyl 4-methacrylate and p-hydroxybutyl 4-methacrylate were preheated to 100°C. The reaction section of the distillation column was maintained at 100°C, the top condensing temperature at 13°C, the reflux ratio at 10:5, the system pressure at 70 kPa, and 30 L / h of air was introduced into the reboiler. The feed rate of 4-hydroxybutyl 4-methacrylate was controlled at 2 kg / h at the top inlet and 1.5 kg / h at the bottom inlet of 4-hydroxybutyl 4-methacrylate. Quantitative analysis of the materials before and after the reaction was performed using gas chromatography. The conversion rate of 4-hydroxybutyl 4-methacrylate was 98%. The proportions of each component in the mixture before and after the reaction were adjusted from... Figure 2 , Figure 3 It can be seen that the proportion of hydroxybutyl methacrylate in the mixture decreased from 26.29% at the beginning of the reaction to 1.44% after the reaction. Quantitative analysis by internal standard method showed that the conversion rate of hydroxybutyl methacrylate was about 98%, indicating that under the above conditions, hydroxybutyl methacrylate was basically completely reacted.

[0049] The condensate from the top of the distillation column is transferred to a vacuum distillation unit. The condensate is a mixture of water from the esterification reaction and unreacted (meth)acrylic acid. The vacuum distillation system is maintained at a pressure of 4–5 kPa and a temperature of 60–65 °C. The water from the esterification reaction is distilled off, leaving (meth)acrylic acid in the bottom container. This (meth)acrylic acid is added to the lower feed inlet storage tank to continue its reaction. The bottom liquid is then transferred to a vacuum rectification unit. The bottom liquid is a mixture of hydroxybutyl 4-(meth)acrylate, p-hydroxyanisole, and hydroquinone. The vacuum rectification system is maintained at a pressure of 2–3 kPa and a temperature of 125–130 °C to obtain butylene di(meth)acrylate with a purity of 98%. Figure 4 It can be seen that the content of butylene di(meth)acrylate is as high as 98%.

[0050] Example 3

[0051] This embodiment provides a continuous production method for neopentyl glycol di(meth)acrylate.

[0052] The packing material is V(SO4) 2-The packing ratio of Fe2O to V(θ ring packing) was uniformly packed at 1:10. Using (meth)acrylic acid and neopentyl glycol as raw materials, 0.5% hydroquinone was dissolved in the raw materials. The (meth)acrylic acid and neopentyl glycol were preheated to 110°C. The reaction section of the distillation column in the reactive distillation equipment was controlled at 110°C, the top condensing temperature at 15°C, the reflux ratio at 10:8, the system pressure at 80 kPa, and 30 L / h of air was introduced into the reboiler. The feed rate of neopentyl glycol was controlled at 2 kg / h at the top inlet and 2 kg / h at the bottom inlet of (meth)acrylic acid. Quantitative analysis of the materials before and after the reaction was performed by gas chromatography, yielding a neopentyl glycol conversion rate of 98.4%.

[0053] The condensate from the top of the distillation column is transferred to a vacuum distillation unit. The condensate is a mixture of water from the esterification reaction and unreacted (meth)acrylic acid. The vacuum distillation system is maintained at a pressure of 4–5 kPa and a temperature of 60–65 °C. The water from the esterification reaction is distilled off, leaving (meth)acrylic acid in the bottom container. This (meth)acrylic acid is added to the lower feed inlet storage tank to continue its reaction. The bottom liquid is then transferred to a vacuum rectification unit. The bottom liquid is a mixture of neopentyl glycol di(meth)acrylic acid and hydroquinone. The vacuum rectification system is maintained at a pressure of 2–3 kPa and a temperature of 130–135 °C to obtain neopentyl glycol di(meth)acrylic acid with a purity of 98%. Figure 5 It can be seen that the content of neopentyl glycol di(meth)acrylate is as high as 98%.

[0054] Example 4

[0055] This embodiment provides a continuous production method for ethylene glycol di(meth)acrylate.

[0056] The packing material was uniformly packed with a ratio of V (mesoporous phenolic resin polymer-based solid acid catalyst) to V (θ-ring packing) of 1:10. Methyl methacrylate and ethylene glycol were used as raw materials. 0.5% p-hydroxyanisole was dissolved in the raw materials by weight. The methyl methacrylate and ethylene glycol were preheated to 70°C. The reaction section of the distillation column in the reactive distillation equipment was maintained at 75°C, the top condensing temperature at 13°C, the reflux ratio at 10:8, the system pressure at 80 kPa, and 10 L / h of air was introduced into the reboiler. The feed rate was controlled at 1 kg / h for ethylene glycol at the top inlet and 5 kg / h for methyl methacrylate at the bottom inlet. Quantitative analysis of the materials before and after the reaction was performed using gas chromatography, showing a 98.8% conversion rate of ethylene glycol.

[0057] The condensate from the top of the distillation column is transferred to a vacuum distillation unit. The condensate is a mixed solution of methanol and methyl methacrylate produced by the transesterification reaction. The vacuum distillation system is controlled at a pressure of 2–3 kPa and a temperature of 50–55 °C. The methanol produced by the transesterification reaction is distilled off, and the remaining liquid is methyl methacrylate. The methyl methacrylate is added to the lower feed inlet storage tank to continue its reaction. The bottom liquid is then transferred to a vacuum rectification unit. The bottom liquid is a mixed solution of ethylene glycol dimethacrylate and p-hydroxyanisole. The vacuum rectification system is controlled at a pressure of 2–3 kPa and a temperature of 105–110 °C to obtain ethylene glycol dimethacrylate with a purity of 98%. Figure 6 It can be seen that the content of ethylene glycol di(meth)acrylate is as high as 98%.

[0058] As can be seen from the above embodiments:

[0059] (1) Selecting a suitable solid acid catalyst and packing material and mixing them evenly to fill the distillation column can avoid the subsequent catalyst separation process;

[0060] (2) By using reactive distillation equipment, reaction separation can be integrated, reducing the investment in separation equipment;

[0061] (3) The pressure reduction of the reactive distillation system can promptly transfer water or low-boiling-point products generated during esterification or transesterification reactions, thereby increasing the conversion rate of raw materials.

[0062] (4) Timely replenishment of the raw materials in the storage tank and transfer of the condensate at the top of the tower and the liquid collected at the bottom of the tower can realize the continuity of the entire reaction process.

[0063] To enable those skilled in the art to better implement this application, the technical solutions provided in this application are described below.

[0064] Reference Figures 7 to 9 As shown, the non-traditional reactive distillation equipment used in the above embodiments includes a distillation column B as described in Embodiment 1, comprising a hollow column body 1, both ends of which are open, and a heating module 2 for heating the column body 1.

[0065] In this embodiment, the column 1 includes an upper distillation column 11 and a lower distillation column 12 connected to each other. A tubular reaction section 13 is arranged between the upper distillation column 11 and the lower distillation column 12. The outer wall of the tubular reaction section 13 is provided with multiple heat source inlets 22 and a heat source outlet 23. During the reaction, heat transfer oil enters the tubular reaction section 13 through the heat source inlets 22 to heat the materials in the tubular reaction section 13. Because multiple heat source inlets 22 are provided, it is ensured that each material is heated evenly during the reaction process, avoiding local accumulation that would affect the reaction efficiency and product yield.

[0066] In practical applications, the two ends of the column 1 are connected to the tower head and the tower bottom, respectively. The column 1 is equipped with a heating module 2, which can improve the reaction efficiency of the material in the column 1, thereby avoiding the accumulation of too much unreacted material in the tower bottom.

[0067] Preferably, in order to ensure that the temperature supplied by the heat transfer oil is insufficient to ensure the temperature required for the reaction at a low temperature, the heating module 2 further includes a heating ring 21 disposed on the column 1. The heating ring 21 can be tubular and filled with hot steam or hot water to achieve the heating of the column 1.

[0068] The heating module 2 can also be a ring-shaped sleeve structure that carries hot steam or hot water, or it can be an electric heating structure, etc. This embodiment does not limit this.

[0069] In this embodiment, both the upper distillation column 11 and the lower distillation column 12 are provided with feed nozzles A. The upper distillation column 11, the lower distillation column 12 are provided with an insulation layer (not shown in the figure) on their exterior. The insulation layer is disposed outside the heating ring 21. There are two heating rings 21 respectively disposed on the upper distillation column 11 and the lower distillation column 12.

[0070] The tubular reaction section 13 includes multiple tubes arranged along the length of the column 1, and the tubes are filled with θ-ring packing.

[0071] The upper distillation column is connected to a gas condensation unit 3, the lower distillation column is connected to a column bottom 4, the column bottom 4 is connected to a first storage unit 5, the gas condensation unit 3 is connected to a second storage unit 6, and the upper and lower distillation columns are fed through a feeding unit 7 respectively; a reboiler C is provided on the column bottom 4.

[0072] In practical applications, the reboiler 4 is heated by the reboiler C, and the feed is added to the distillation column B by the feeding unit 7. The gas generated by the reaction distillation is processed by the gas condensation unit 3 and then output to the second storage unit 6. The liquid in the reboiler 4 is output to the first storage unit 5, so that the distillation device can realize continuous reaction.

[0073] Both the upper and lower distillation columns are equipped with heating rings to improve reaction efficiency.

[0074] Specifically, the first storage unit 5 includes a first temporary storage tank 52 connected to the bottom of the tower 4 via a first conveying pipe 51; the second storage unit 6 includes a plurality of second temporary storage tanks 62 connected to the gas condensation unit 3 via a second conveying pipe 61.

[0075] Both the input and output ends of the first temporary storage tank 52 and the second temporary storage tank 62 are equipped with valves E.

[0076] In this embodiment, the gas condensation unit 3 includes a column head 31 connected to the upper distillation column and the second storage unit 6, and a first condensation assembly 32 extending into the column head 31. The first condensation assembly 32 is connected to a low-temperature circulating water bath 33, and the second delivery pipe 61 is connected to the column head 31.

[0077] The column head 31 includes an outlet section connected to the upper distillation column and a condenser section connected to the outlet section. The first condenser assembly 32 extends into the condenser section. The lower part of the condenser section and the outlet section is also provided with a reflux pipe and other structures connecting the condenser section and the outlet section. The product generated by the reactive distillation is condensed by the first condenser assembly 32. A portion of the condensate is returned to the distillation column B as reflux liquid from the reflux pipe, and the remaining condensate is the product, that is, the part output to the second temporary storage tank 62. The second delivery pipe 61 is connected to the bottom of the condenser section.

[0078] The first delivery pipe 51 is also equipped with a second condensation component D, which is connected to the low-temperature circulating water bath 33 to further condense the liquid obtained by reactive distillation and ensure product quality.

[0079] In this embodiment, the feeding unit 7 includes a first feeding tank 72 connected to the feeding nozzle of the upper distillation column through a first feeding pipe 71, and a second feeding tank 74 connected to the feeding nozzle of the lower distillation column through a second feeding pipe 73. The first feeding pipe 71 and the second feeding pipe 73 are each equipped with a feeding pump 75 and a valve E.

[0080] It also includes an air compressor feeding module 8, which is connected to the first feeding tank 72, the second feeding tank 74, the first temporary storage tank 52, the second temporary storage tank 62, and the tower head 31 through an air supply pipe 81.

[0081] The air-compressed feeding module 8 works in conjunction with the feeding pump 75 to transport materials in the first feeding tank 72 and the second feeding tank 74, ensuring the normal operation of the work.

[0082] At the same time, it also ensures the output of materials in the first temporary storage tank 52, the second temporary storage tank 62, and the tower head 31. The gas supply pipe 81 is connected to the top of the condenser section of the tower head 31.

[0083] Specifically, the compressed air feeding module 8 includes a vacuum pump 82 and a vacuum buffer tank 83 connected to the vacuum pump 82. The air supply pipe 81 is connected to the vacuum buffer tank 83. The output and input ends of the vacuum buffer tank 83 are also equipped with valves E. The vacuum buffer tank 83 also has a pressure relief pipe, which is also equipped with a valve E.

[0084] Preferably, heat exchange components F are provided on the first feed pipe 71 and the second feed pipe 73. The heat exchange components F are connected to a high-temperature circulating water bath G, so that the materials output from the first feed tank 72 and the second feed tank 74 are at a temperature close to that inside the distillation column B, thus ensuring the stability of the distillation system.

[0085] Preferably, it further includes a control module 9, which includes a controller 91, a control motherboard 92 disposed within the controller 91, and a touch screen 93 disposed on the controller 91;

[0086] The control module 9 also includes a temperature sensor 94 installed in the upper distillation column, lower distillation column, reboiler 4, reboiler C, column head 31, first condenser assembly 32, second condenser assembly D, and heat exchange assembly F, as well as a pressure sensor 95 installed in the vacuum buffer tank 83.

[0087] The column head 31 is also equipped with a reflux ratio device 96 located at the output end. That is, the reflux ratio device 96 is located at the output end of the condenser to ensure the separation effect of the distillation process.

[0088] The temperature sensor 94, pressure sensor 95, low-temperature circulating water bath 33, high-temperature circulating water bath G, heating ring, reboiler C, feed pump 75, vacuum pump 82, reflux ratio device 96, and touch screen 93 are all electrically connected to the control main board 92.

[0089] Temperature data of the corresponding device is detected by temperature sensor 94, and pressure data in vacuum buffer tank 83 is detected by pressure sensor 95. The two types of data are transmitted to control motherboard 92. After processing by control motherboard 92, temperature and pressure information are displayed on touch screen 93, which can realize real-time monitoring of temperature and pressure parameters.

[0090] The controller 91 is also equipped with a control button group 97 for controlling the operation of the low temperature circulating water bath 33, the high temperature circulating water bath G, the heating ring, the reboiler C, the feed pump 75, the vacuum pump 82, and the reflux ratio device 96.

[0091] In this embodiment, the liquid in the first temporary storage tank 83 can be manually removed and analyzed. Based on the parameter information collected by the temperature sensor 94 and the pressure sensor 95, as well as the analysis results of the liquid in the first temporary storage tank 83, the operation of the low-temperature circulating water bath 33, the high-temperature circulating water bath G, the heating ring, the reboiler C, the feed pump 75, the vacuum pump 82, and the reflux ratio device 96 can be controlled through the touch control screen and the control button group 97. This allows for real-time regulation of the temperature of each component of the device and the pressure of the vacuum buffer tank 83.

[0092] The low-temperature circulating water bath 33 is equipped with a refrigeration component, the high-temperature circulating water bath G is equipped with a heating component, and the low-temperature circulating water bath 33 and the high-temperature circulating water bath G are also equipped with a circulation pump. The refrigeration component, the heating component, and the circulation pump are electrically connected to the control main board 92.

[0093] The reboiler C is also equipped with a feed pipe for adding materials into the reboiler C, and the feed pipe is also equipped with a valve E; the valve E is a plug valve.

[0094] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for the continuous production of (meth)acrylic polyol esters, characterized in that, Includes the following steps: Pretreatment: The raw material is preheated, the polymerization inhibitor is added to the raw material to dissolve, and stirred evenly. The solid acid catalyst and packing material are mixed evenly and then packed into the distillation column. reaction: The corresponding (meth)acrylic acid polyol ester is produced using polyols and (meth)acrylic acid as raw materials; or polyols and (meth)acrylic acid low carbon alcohol esters as raw materials; or (meth)acrylic acid polyol monoesters and (meth)acrylic acid as raw materials, and air is introduced into the bottom of the column; The reaction process utilizes unconventional reactive distillation equipment, and the reactive distillation esterification reaction is carried out by controlling the feed rate, reaction temperature, system pressure, air volume, reflux ratio, and conditions. Post-processing: The condensate at the top of the column is subjected to vacuum distillation to remove water or low-boiling-point products. The remaining distillate is the desired product or unreacted raw material. If it is raw material, it is returned to continue the reaction. If it is product, it can be collected. The liquid collected in the bottom of the column is subjected to vacuum distillation to separate the raw material or product. If it is raw material, it is returned to continue the reaction. If it is product, it can be collected. The solid acid catalyst is a perfluorosulfonic acid ion exchange resin, Al2O3 / SO4 2- , SO4 2- / Fe2O or a mesoporous phenol resin polymer-based solid acid catalyst; The aforementioned non-traditional reactive distillation equipment relies on a heated distillation column to provide heat for the esterification reaction, while the reboiler is not heated. The pressure of the reactive distillation system is 5–100 kPa, and the temperature of the distillation column is 60–240 °C.

2. The method of continuously producing (meth)acrylic polyol esters according to claim 1, characterized in that: The (meth)acrylic acid mentioned is acrylic acid or methacrylic acid.

3. The method of continuously producing (meth)acrylic polyol esters according to claim 1, characterized in that: The polyol is ethylene glycol, propylene glycol, glycerol, pentaerythritol, or sorbitol.

4. The method of continuously producing (meth)acrylic polyol esters according to claim 1, characterized in that: The feed rate of the polyol is 1-100 kg / h.

5. The method of continuously producing (meth)acrylic polyol esters according to claim 1, characterized in that: The polymerization inhibitor is one or more of hydroquinone, p-hydroxyanisole, phenothiazine, diethylhydroxylamine, trinitrobenzene, m-dinitrobenzene, m-nitrochlorobenzene, nitrobenzene, and sodium nitrite, and its dosage is 0.05% to 2% of the raw material mass.

6. The method of continuously producing (meth)acrylic polyol esters according to claim 1, characterized in that: The air flow rate through the tower bottom is 5-100 L / h.

7. The method of continuously producing (meth)acrylic polyol esters according to claim 1, characterized in that: The solid acid catalyst is packed into a distillation column, with V (solid acid):V (packing material) = 1:100 to 10:

1.

8. The method of continuously producing (meth)acrylic polyol esters according to claim 1, characterized in that: The reflux ratio at the top of the reactive distillation equipment is 10:1 to 10:

10.

9. The method of continuously producing (meth)acrylic polyol esters according to claim 1, characterized in that: (Meth)acrylates with C4 to C6 carbon atoms are condensed at the top of the column, while (meth)acrylates with more than C7 carbon atoms are collected at the bottom of the column.

Images