Preparation method of acrylic acid series hydroxyalkyl ester

Abstract

The invention relates to the technical field of fine chemical engineering, in particular to a preparation method of acrylic acid series hydroxyalkyl ester, the acrylic acid series hydroxyalkyl ester is prepared according to the following reaction formula: # imgabs0 #, in which R1 is H or CH3 or CH3CH2, R2 is H or CH3 or CH3CH2; m is the polymerization degree of alkylene oxide, and m is an integer value of 1-50; the device specifically comprises five preparation units, namely a pre-preparation unit, a primary continuous reaction unit, a refining unit, a secondary polymerization unit and a comprehensive treatment unit. According to the preparation method of the acrylic acid series hydroxyalkyl ester, no solid waste or liquid waste is generated in the preparation process, green preparation of the acrylic acid series hydroxyalkyl ester can be achieved, the preparation process is safe and reliable, and the obtained product is high in quality.

Description

Technical Field

[0001] The present invention relates to the technical field of fine chemical engineering, and particularly to a preparation method of acrylic hydroxyalkyl ester. Background Art

[0002] Currently, the preparation of acrylic hydroxyalkyl ester is mainly obtained by two methods: addition polymerization of acrylic monomer and alkylene oxide or esterification of acrylic monomer and low molecular weight diol. The addition reaction follows the batch kettle stirring / circulation process, with violent reactions, and the reaction heat is extremely easy to accumulate and cause danger, and a large amount of by-product polymers are disposed of as waste. Due to the relatively high polymerization temperature in the esterification reaction, the unsaturated double bonds of acrylic monomers are easily damaged, affecting the quality of the final product.

[0003] Therefore, from the perspectives of reducing the safety risks and comprehensive utilization of by-products in the reaction process, as well as reducing costs and improving product quality, it is necessary to develop a new preparation method. Summary of the Invention

[0004] The present invention provides a preparation method of acrylic hydroxyalkyl ester to solve the above technical deficiencies, effectively improving the product quality and reducing the risks and operating costs in the production process.

[0005] The present invention discloses a preparation method of acrylic hydroxyalkyl ester, and the preparation is as follows in the reaction formula:

[0006]

[0007] Wherein: R 1 is H or CH 3 or CH 3 CH 2 , R 2 is H or CH 3 or CH 3 CH 2 ; m is the polymerization degree of alkylene oxide, and m is an integer value from 1 to 50.

[0008] It includes a total of five preparation units: a pre-preparation unit, a primary continuous reaction unit, a refining unit, a secondary polymerization unit, and a comprehensive treatment unit.

[0009] The pre-preparation unit includes multiple sets of parallel premixing kettles. The top of the premixing kettle is provided with an acrylic initiator feed port, a catalyst dosing port, an inhibitor dosing port, a nitrogen gas port, and a vacuum port, and the vacuum pipeline is connected to an organic matter separation device.

[0010] The primary continuous reaction unit is composed of a continuous flow microchannel reactor, which includes a preheating section, a reaction section, and a maintaining section. The material inlet of the preheating section is connected to the bottom of the premixing kettle through a delivery pump, and the reaction section is provided with independent feed channels for ethylene oxide and propylene oxide.

[0011] The refining unit includes a vacuum buffer tank, an absorption tower, a concentration tower, a distillation column, and a polybuffer tank. The vacuum buffer tank consists of two parallel negative-pressure storage tanks. The feed inlet in the lateral normal direction of the vacuum buffer tank is connected to the outlet of the continuous flow microchannel reactor. A nitrogen pipeline is provided at the top of the vacuum buffer tank. The material outlet at the top of the vacuum buffer tank is connected to the absorption tower. The bottom of the vacuum buffer tank is connected to the feed pipeline of the first distillation column;

[0012] The absorption tower is an acid absorption tower. The bottom outlet of the absorption tower feeds the concentration tower through a feed pump;

[0013] The bottom of the first distillation column is connected to the feed inlet of the second distillation column through a pipeline. The bottom of the second distillation column is connected to the feed inlets of the polybuffer tank and the third distillation column respectively through pipelines;

[0014] The secondary polymerization unit consists of an alkylation kettle. Feed inlets for ethylene oxide and propylene oxide are provided at the top of the alkylation kettle. The polybuffer tank is connected to the alkylation kettle. The alkylation kettle is provided with inlets for polymerization inhibitor and catalyst;

[0015] The comprehensive treatment unit consists of a multi-functional polymerization kettle. The bottom of the alkylation kettle is connected to the multi-functional polymerization kettle through a transfer pump. The concentration tower is connected to the multi-functional polymerization kettle through a pipeline. The organic matter separation equipment is connected to the multi-functional polymerization kettle.

[0016] The catalyst added to the premixing kettle is one or more of potassium hydroxide, sodium hydroxide, sodium methoxide, triethylamine, tributylamine, and triphenyl phosphite. The polymerization inhibitor is one or more of hydroquinone, 2,6-di-tert-butyl-p-cresol, phenothiazine, and p-methoxyphenol. The temperature of the premixing kettle is 20 - 40°C.

[0017] The temperature of the preheating section of the continuous flow microchannel reactor is 40 - 65°C, the reaction section temperature is 65 - 90°C, the reaction pressure is 0.05 MPa - 0.3 MPa, the temperature of the maintaining section is 80 - 90°C, and the residence time in the maintaining section is 60 - 240 min; in the primary continuous reaction unit, the molar ratio of the acrylic acid-based monomer to ethylene oxide or propylene oxide is 1:1.2 - 2.0.

[0018] In the refining unit, the temperature of the buffer tank is 30 - 60°C, and the pressure is -0.05 - 0.05 MPa; the absorption tower is an acid absorption tower, using concentrated sulfuric acid as a catalyst and water as an absorbent, with the operating temperature of the absorption tower being 40 - 90°C and at atmospheric pressure; the operating temperature of the concentration tower is 95 - 115°C, and the operating pressure is -0.08 - 0.02 MPa; the first distillation column operates under negative pressure, with the top temperature being 80 - 105°C, the second distillation column operates under negative pressure, with the top temperature being 110 - 125°C, and the third distillation column operates under negative pressure, with the top temperature being 130 - 145°C.

[0019] In the alkylation kettle of the secondary polymerization unit, the reaction temperature is 120 - 160°C, and the operating pressure is 0.05 - 0.4 MPa.

[0020] The multifunctional polymerization kettle in the comprehensive treatment unit is used for esterification synthesis of acrylic hydroxyalkyl esters, for end-capping modification of acrylic hydroxyalkyl esters, and for synthesis of polycarboxylic acid mother liquor.

[0021] When the multifunctional polymerization kettle in the comprehensive treatment unit is used for esterification synthesis of acrylic hydroxyalkyl esters, the by-product ethylene glycol, oligomeric polyethylene glycol or propylene glycol, and oligomeric polypropylene glycol concentrates concentrated in the concentration tower, as well as the heavy components of the third distillation column, are fed into the multifunctional polymerization kettle, and solution polymerization is completed by dropping acrylic monomers to obtain an aqueous solution of acrylic hydroxyalkyl esters; a polymerization inhibitor needs to be added before esterification, and the dosage is 0.3 - 5‰ of the total dry basis active substances; p-toluenesulfonic acid is selected as the catalyst, and the dosage is 0.5 - 3% of the total dry basis active substances, with the esterification temperature being 120 - 180°C and the reaction time being 2 - 4 h.

[0022] When the multifunctional polymerization kettle in the comprehensive treatment unit is used for end-capping modification of acrylic hydroxyalkyl esters, the acrylic hydroxyalkyl esters synthesized in the alkylation kettle are sent to the multifunctional polymerization kettle by a transfer pump, and end-capping reaction is carried out by dropping an end-capping agent to obtain end-capped derivatives of acrylic hydroxyalkyl esters. The end-capping agent is one or more of methyl chloride, acetic anhydride, and benzyl chloride. The reaction temperature is 10 - 90°C, and the reaction time is 2 - 8 h. In this reaction, a catalyst of sodium hydroxide or potassium hydroxide solution with a mass fraction of 30 - 50% is selected, and the dosage is 0.5 - 5% of the total solid content of the reaction substrate.

[0023] When the multifunctional polymerization kettle of the comprehensive treatment unit is used to synthesize the polycarboxylic acid mother liquor, the aqueous solution of acrylic hydroxyalkyl ester obtained by esterification synthesis and the functional additives are put into the multifunctional polymerization kettle to synthesize the polycarboxylic acid mother liquor. The functional additives include macromonomer, initiator, chain transfer agent, functional monomer and water. The macromonomer is one or more of HPEG, TPEG, VPEG, EPEG and GPEG; the initiator is selected from one or more of 10-30% hydrogen peroxide, ammonium persulfate and Rongalite; the chain transfer agent is selected from one or more of mercaptoacetic acid, mercaptopropionic acid, mercaptoethanol and sodium methallylsulfonate; the functional monomer is one or more of 1-methylallyl acetate, 2-methylallyl acetate, acrylic mono-polyhydroxyalkyl ester, acrylic di-polyhydroxyalkyl ester, acrylic acid, methacrylic acid and acrylamide; the molar ratio of the macromonomer to the functional monomer is 1:2.5-4.5; the synthesis temperature is 15-60 °C, the reaction time is 0.5-4 h, and the aging time is 0.5-2 h.

[0024] The preparation method of an acrylic hydroxyalkyl ester obtained by the present invention generates no solid waste or liquid waste during the preparation process, can realize the green preparation of the acrylic hydroxyalkyl ester, the preparation process is safe and reliable, and the obtained product has high quality. Brief Description of the Drawings

[0025] Figure 1 It is the preparation flow chart of the present invention. Detailed Embodiments

[0026] To further illustrate the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following combines the drawings and preferred embodiments to detail the specific embodiments, structures, features and effects according to the present invention as follows.

[0027] Example 1:

[0028] As Figure 1 shown, the present invention discloses a preparation method of an acrylic hydroxyalkyl ester. The first step: using acrylic acid monomer as the raw material, carrying out ring-opening polymerization with ethylene oxide, as shown in Formula 2:

[0029]

[0030] n is the polymerization degree of ethylene oxide, n = 1-5.

[0031] The molar ratio of acrylic acid to ethylene oxide is 1:1.2-1.5, and the catalyst is preferably triethylamine. The ratio of the catalyst to the total mass of acrylic acid and ethylene oxide is 3-15:1000. The inhibitor can be preferably p-methoxyphenol. The ratio of the inhibitor to the total mass of acrylic acid and ethylene oxide is 1-15:10000.

[0032] Put acrylic acid and polymerization inhibitor into the first premixing kettle in sequence, start stirring, and control the temperature at 20 - 40°C. After mixing for 20 min, add triethylamine, continue stirring for 15 - 20 min, and at the same time start the vacuum system. The escaped light components are centrally collected by the organic matter separation equipment and reserved. To ensure the continuous operation of the subsequent process sections, the second and third premixing kettles should also repeat the above operations.

[0033] Under the protection of nitrogen, the uniformly mixed material enters the preheating section of the continuous flow microchannel reactor. The temperature of the preheating section is controlled at 45 - 60°C, and the temperature at the outlet of the preheating section is 60 - 65°C.

[0034] The material continues to enter the reaction section of the continuous flow microchannel reactor, and ethylene oxide is introduced. The mixing ratio of ethylene oxide and the material is realized by the built-in automatic control system. The operating temperature of the reaction section is 65 - 80°C, the residence time is 60 - 90 s, and the reaction pressure is 0.05 - 0.25 MPa.

[0035] The operating temperature of the maintenance section of the continuous flow microchannel reactor is 80 - 85°C, and the residence time is 60 - 100 s.

[0036] The reaction material enters the pressure reducing buffer tank. The operating temperature of the pressure reducing buffer tank is 30 - 60°C, and the operating pressure is -0.05 MPa to 0.05 MPa. Nitrogen is introduced into the gas distribution plate placed inside the tank body for bubbling, and at the same time vacuum is pumped. The tail gas enters the absorption tower, and the operating temperature of the absorption tower is 40 - 80°C.

[0037] The material stripped in the pressure reducing buffer tank enters the first distillation column, and the top temperature is 80 - 95°C. The overhead product is hydroxyethyl acrylate. The bottom fraction enters the second distillation column, and the top temperature is 100 - 120°C. The overhead product is dihydroxyethyl acrylate. The bottom fraction enters the third distillation column, and the top temperature is 130 - 140°C. The overhead product is polyhydroxyethyl acrylate with a degree of polymerization of 3 - 6. The bottom heavy components enter the bottom product collection tank for collection.

[0038] Step 2: The addition of polyhydroxyethyl acrylate and ethylene oxide / propylene oxide is as shown in Formula 3:

[0039]

[0041] n is the degree of polymerization of ethylene oxide, n = 1 - 5; i is the addition number of ethylene oxide, i = 5 - 10; j is the addition number of propylene oxide, j = 0 - 3; q is the ethylene oxide addition degree of the propylene oxide - capped product of polyhydroxyethyl acrylate, q = n + i.

[0042] The molar ratio of polyhydroxyethyl acrylate to ethylene oxide and propylene oxide is 1:5 to 10:0 to 3. The catalyst can preferably be powdered high-purity potassium hydroxide. The ratio of the catalyst to the total mass of the reactants is 0.5 to 5:100. The polymerization inhibitor can preferably be hydroquinone. The ratio of the polymerization inhibitor to the total mass of the reactants is 0.5 to 3:1000.

[0043] Put the polyhydroxyethyl acrylate taken out from the third distillation column into the alkylation kettle, and successively add the catalyst and the polymerization inhibitor, and displace with nitrogen for 2 to 5 times. Start the circulation system, mix for 15 to 30 minutes, heat up to 80 to 105 °C, dehydrate under vacuum for 10 to 20 minutes, continue to heat up to 110 °C, add ethylene oxide to the alkylation kettle, the reaction temperature is 110 to 140 °C, the reaction pressure is 0.05 to 0.2 MPa, after adding, age for 15 to 20 minutes, then add propylene oxide, the reaction temperature is 110 to 135 °C, the reaction pressure is 0.05 to 0.3 MPa, after adding, age for 20 to 30 minutes to obtain the polyhydroxyethyl acrylate propylene oxide end-capped product.

[0044] Step 3: Synthesize the polycarboxylic acid mother liquor from the polyhydroxyethyl acrylate propylene oxide end-capped product, as shown in Formula 4:

[0045]

[0046] x, y, z, and w are the molar ratios of the polyhydroxyethyl acrylate propylene oxide end-capped product, HPEG, acrylic acid, and 1-methylallyl acetate, and x:y:z:w = 1 to 3:10:35 to 42:2 to 8.

[0047] The initiator is selected as 27.5% hydrogen peroxide, and the addition amount is 2 to 5% of the total amount of the bottom material; the reducing agent is selected as Rongalite, and the addition amount is 2 to 3.5% of the total amount of the bottom material; the chain transfer agent is selected as mercaptopropionic acid, and the addition amount is 1 to 2.5% of the total amount of the bottom material. The synthesis temperature is 30 to 60 °C, the reaction time is 2 to 4 hours, and the aging time is 1 hour.

[0048] The obtained polycarboxylic acid mother liquor can be used as a concrete admixture, or can be dried to form a powder and used as a cement grinding aid, a water reducer for ceramics or refractory materials, etc.

[0049] Example 2:

[0050] As Figure 1 shown, the present invention discloses a preparation method of a hydroxyalkyl acrylate of the acrylic acid series.

[0051] Step 1: Using methacrylic acid monomer as the raw material, carry out ring-opening polymerization with ethylene oxide, as shown in Formula 5:

[0052]

[0053] n is the degree of polymerization of ethylene oxide, and n = 1 to 5.

[0054] The molar ratio of methacrylic acid to ethylene oxide is 1:1.2 - 1.8, and the catalyst can preferably be triethylamine. The ratio of the catalyst to the total mass of methacrylic acid and ethylene oxide is 3 - 20:1000. The inhibitor can preferably be hydroquinone. The ratio of the inhibitor to the total mass of methacrylic acid and ethylene oxide is 1 - 20:10000.

[0055] Put methacrylic acid and the inhibitor into the first premixing kettle in sequence, start stirring, and control the temperature at 20 - 40°C. After mixing for 20 min, add triethylamine and continue stirring for 15 - 20 min, and at the same time start the vacuum system. The escaped light components are centrally collected by the organic matter separation equipment and reserved. To ensure the continuous operation of the subsequent process sections, the second premixing kettle and the third premixing kettle should also repeat the above operations.

[0056] The uniformly mixed material enters the preheating section of the continuous flow microchannel reactor under the protection of nitrogen. The temperature of the preheating section is controlled at 45 - 60°C, and the temperature at the outlet of the preheating section is 60 - 65°C.

[0057] The material continues to enter the reaction section of the continuous flow microchannel reactor, and ethylene oxide is introduced. The mixing ratio of ethylene oxide to the material is realized by the built-in automatic control system. The operating temperature of the reaction section is 70 - 90°C, the residence time is 60 - 90 s, and the reaction pressure is 0.05 - 0.25 MPa.

[0058] The operating temperature of the continuous flow microchannel reactor maintenance section is 80 - 90°C, and the residence time is 60 - 100 s.

[0059] The reaction material enters the pressure reduction buffer tank. The operating temperature of the pressure reduction buffer tank is 30 - 60°C, and the operating pressure is -0.05 MPa - 0.05 MPa. Nitrogen is introduced into the gas distribution plate placed inside the tank body for bubbling, and at the same time, vacuum is pumped. The tail gas enters the absorption tower, and the operating temperature of the absorption tower is 50 - 90°C.

[0060] The material after stripping in the pressure reduction buffer tank enters the first distillation column, and the top temperature is 80 - 95°C. The overhead product is 2-hydroxyethyl methacrylate. The bottom fraction enters the second distillation column, and the top temperature is 100 - 120°C. The overhead product is bis(2-hydroxyethyl) methacrylate. The bottom fraction enters the third distillation column, and the top temperature is 130 - 140°C. The overhead product is poly(2-hydroxyethyl) methacrylate with a degree of polymerization of 3 - 6. The bottom heavy components enter the bottom product collection tank for collection.

[0061] Step 2: The addition of poly(2-hydroxyethyl) methacrylate and ethylene oxide / propylene oxide is as shown in Equation 6:

[0062]

[0063] n is the degree of polymerization of ethylene oxide, n = 1 - 5; i is the number of ethylene oxide additions, i = 5 - 10; j is the number of propylene oxide additions, j = 0 - 3; q is the degree of ethylene oxide addition of the polyhydroxyethyl methacrylate propylene oxide-capped product, q = n + i.

[0064] The molar ratio of polyhydroxyethyl methacrylate to ethylene oxide and propylene oxide is 1:5 - 10:1 - 3. The catalyst can preferably be powdered high-purity potassium hydroxide. The ratio of the catalyst to the total mass of the reactants is 0.5 - 5:100. The inhibitor can preferably be hydroquinone. The ratio of the inhibitor to the total mass of the reactants is 0.5 - 3:1000.

[0065] Put the polyhydroxyethyl methacrylate taken out from the third distillation column into the alkylation kettle, add the catalyst and inhibitor in sequence, and displace with nitrogen 2 - 5 times. Start the circulation system and mix for 15 - 30 min. Heat up to 80 - 105 °C and dehydrate under vacuum for 10 - 20 min. Continue to heat up to 110 °C, and add the ethylene oxide and propylene oxide mixture mixed by the pipeline mixer to the alkylation kettle. The reaction temperature is 110 - 150 °C, the reaction pressure is 0.05 - 0.3 MPa. After adding, cure for 20 - 60 min to obtain polyhydroxyethyl methacrylate hydroxypropyl ester.

[0066] Step 3: Synthesize the polycarboxylic acid mother liquor from polyhydroxyethyl methacrylate hydroxypropyl ester, as shown in Formula 7:

[0067]

[0068] x, y, z, w are the molar ratios of polyhydroxyethyl methacrylate hydroxypropyl ester, HPEG, acrylic acid, and 1-methylallyl acetate, x:y:z:w = 1 - 4:10:35 - 42:2 - 6.

[0069] The initiator is selected as 27.5% hydrogen peroxide, and the addition amount is 2 - 5% of the total amount of the bottom material; the reducing agent is selected as Rongalite, and the addition amount is 2 - 3.5% of the total amount of the bottom material; the chain transfer agent is selected as mercaptopropionic acid, and the addition amount is 1 - 2.5% of the total amount of the bottom material. The synthesis temperature is 30 - 60 °C, the reaction time is 2 - 4 h, and the curing time is 1 h.

[0070] The obtained polycarboxylic acid mother liquor can be used as a concrete admixture, or can be dried to form a powder and used as a cement grinding aid, a water reducing agent for ceramics or refractory materials, etc.

[0071] Example 3:

[0072] As Figure 1 shown, the present invention discloses a preparation method of an acrylic hydroxyalkyl ester,

[0073] Step 1: Using methacrylic acid monomer as the raw material, carry out ring-opening polymerization with ethylene oxide, as shown in Formula 8:

[0074]

[0075] n is the degree of polymerization of ethylene oxide, and n = 1 - 5.

[0076] The molar ratio of methacrylic acid to ethylene oxide is 1:1.2 - 1.8, and triethylamine can be preferably used as the catalyst. The ratio of the catalyst to the total mass of methacrylic acid and ethylene oxide is 3 - 20:1000. Hydroquinone can be preferably used as the inhibitor. The ratio of the inhibitor to the total mass of methacrylic acid and ethylene oxide is 1 - 20:10000.

[0077] Charge methacrylic acid and the inhibitor into the first premixing kettle in sequence, start stirring, and control the temperature at 20 - 40°C. After mixing for 20 min, add triethylamine, continue stirring for 15 - 20 min, and at the same time start the vacuum system. The escaped light components are centrally collected by the organic matter separation equipment and reserved. To ensure the continuous operation of the subsequent sections, the second premixing kettle and the third premixing kettle should also repeat the above operations.

[0078] Under the protection of nitrogen, the uniformly mixed material enters the preheating section of the continuous flow microchannel reactor. The temperature of the preheating section is controlled at 45 - 60°C, and the temperature at the outlet of the preheating section is 60 - 65°C.

[0079] The material continues to enter the reaction section of the continuous flow microchannel reactor, and ethylene oxide is introduced. The mixing ratio of ethylene oxide and the material is realized by the built-in automatic control system. The operating temperature of the reaction section is 70 - 90°C, the residence time is 60 - 90 s, and the reaction pressure is 0.05 - 0.30 MPa.

[0080] The operating temperature of the maintenance section of the continuous flow microchannel reactor is 80 - 90°C, and the residence time is 60 - 100 s.

[0081] The reaction material enters the pressure reduction buffer tank. The operating temperature of the pressure reduction buffer tank is 30 - 60°C, and the operating pressure is -0.05 MPa - 0.05 MPa. Nitrogen is introduced into the gas distribution plate placed inside the tank body for bubbling, and at the same time, vacuum is pumped. The tail gas enters the absorption tower, and the operating temperature of the absorption tower is 60 - 90°C.

[0082] The material stripped in the pressure reduction buffer tank enters the first distillation column, and the top temperature is 80 - 95°C. The overhead product is hydroxyethyl methacrylate. The bottom fraction enters the second distillation column, and the top temperature is 100 - 120°C. The overhead product is dihydroxyethyl methacrylate. The bottom fraction enters the third distillation column, and the top temperature is 130 - 140°C. The overhead product is polyhydroxyethyl methacrylate with a degree of polymerization of 3 - 6. The bottom heavy components enter the bottom collection tank for collection.

[0083] Step 2: The addition of polyhydroxyethyl methacrylate and ethylene oxide / propylene oxide is as shown in Formula 9:

[0084]

[0085] n is the degree of polymerization of ethylene oxide, n = 1 - 5; i is the number of ethylene oxide additions, i = 5 - 10; j is the number of propylene oxide additions, j = 0 - 3; q is the degree of ethylene oxide addition of the propylene oxide-capped product of polyhydroxyethyl methacrylate, q = n + i.

[0086] The molar ratio of polyhydroxyethyl methacrylate to ethylene oxide and propylene oxide is 1:5 - 10:1 - 3. The catalyst can preferably be powdered high-purity potassium hydroxide. The ratio of the catalyst to the total mass of the reactants is 0.5 - 5:100. The inhibitor can preferably be hydroquinone. The ratio of the inhibitor to the total mass of the reactants is 0.5 - 3:1000.

[0087] Put the polyhydroxyethyl methacrylate taken out from the third distillation column into the alkylation kettle, add the catalyst and inhibitor in sequence, and displace with nitrogen for 2 - 5 times. Start the circulation system and mix for 15 - 30 min. Heat up to 80 - 105 °C and dehydrate under vacuum for 10 - 20 min. Continue to heat up to 110 °C, add ethylene oxide to the alkylation kettle, with the reaction temperature of 110 - 140 °C and the reaction pressure of 0.05 - 0.2 MPa. After adding, age for 15 - 20 min, then add propylene oxide, with the reaction temperature of 110 - 135 °C and the reaction pressure of 0.05 - 0.3 MPa. After adding, age for 20 - 30 min to obtain the propylene oxide-capped product of polyhydroxyethyl methacrylate.

[0088] Step 3: Synthesize the polycarboxylic acid mother liquor from polyhydroxyethyl methacrylate hydroxypropyl ester, as shown in Formula 10:

[0089]

[0090] x, y, z, and w are the molar ratios of polyhydroxyethyl methacrylate hydroxypropyl ester, HPEG, acrylic acid, and 1-methylallyl acetate, x:y:z:w = 1 - 3:10:35 - 42:2 - 9.

[0091] The initiator is selected as 30% hydrogen peroxide, and the addition amount is 2 - 5% of the total amount of the bottom material; the reducing agent is selected as Rongalite, and the addition amount is 2 - 3.5% of the total amount of the bottom material; the chain transfer agent is selected as mercaptopropionic acid, and the addition amount is 1 - 2.5% of the total amount of the bottom material. The synthesis temperature is 30 - 60 °C, the reaction time is 2 - 4 h, age for 1 h, add 30% NaOH solution for neutralization, the addition amount of the alkali solution is 8 - 12% of the total feeding amount, and neutralize for 15 - 20 min.

[0092] The obtained polycarboxylic acid mother liquor can be used as a concrete admixture, or can be dried to form a powder and used as a cement grinding aid, a water reducer for ceramics or refractory materials, etc.

[0093] The above are only the preferred embodiments of the present invention and do not impose any formal restrictions on the present invention. Although the present invention has been disclosed above in the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments by using the above-disclosed technical content within the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention, any simplification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing hydroxyalkyl acrylate, characterized in that: Prepared as the following reaction formula: Wherein: R1 is H or CH3 or CH3CH2, R2 is H or CH3 or CH3CH2; m is the degree of polymerization of alkylene oxide, and m is an integer value of 1-50.

2. The method for preparing a hydroxyalkyl acrylate according to claim 1, characterized in that: It includes five preparation units, namely, pre-preparation unit, primary continuous reaction unit, refining unit, secondary polymerization unit and comprehensive treatment unit; The pre-preparation unit comprises a plurality of parallel pre-mixing kettles, the top of which is provided with an acrylic acid initiator feed port, a catalyst feed port, an inhibitor feed port, a nitrogen pipe port and a vacuum pipe port, and the vacuum pipe port is connected to the organic separation equipment; The primary continuous reaction unit is composed of a continuous flow microchannel reactor, which includes a preheating section, a reaction section and a maintenance section. The material inlet of the preheating section is connected to the bottom of the premixing kettle through a delivery pump, and the reaction section is provided with independent feed channels for ethylene oxide and propylene oxide; The refining unit includes a vacuum buffer tank, an absorption tower, a concentration tower, a distillation tower, and a polymer buffer tank. The vacuum buffer tank is two sets of negative pressure storage tanks connected in parallel. The feed inlet in the lateral normal direction of the vacuum buffer tank is connected to the discharge port of the continuous flow microchannel reactor. A nitrogen pipeline is provided on the top of the vacuum buffer tank. The material outlet on the top of the vacuum buffer tank is connected to the absorption tower. The bottom of the vacuum buffer tank is connected to the feed pipeline of the first distillation tower. The absorption tower is an acid absorption tower, and the bottom discharge port of the absorption tower supplies materials to the concentration tower through a feed pump; The bottom of the first distillation tower is connected to the feed inlet of the second distillation tower through a pipeline, and the bottom of the second distillation tower is connected to the polymer buffer tank and the feed inlet of the third distillation tower through pipelines respectively; The secondary polymerization unit is composed of an alkylation kettle, the top of which is provided with feed ports for ethylene oxide and propylene oxide, a polymerization buffer tank is connected to the alkylation kettle, and the alkylation kettle is provided with ports for feeding a polymerization inhibitor and a catalyst; The comprehensive treatment unit is composed of a multifunctional polymerization kettle, the bottom of the alkylation kettle is connected to the multifunctional polymerization kettle through a delivery pump, the concentration tower is connected to the multifunctional polymerization kettle through a pipeline, and the organic separation equipment is connected to the multifunctional polymerization kettle.

3. The method for preparing a hydroxyalkyl acrylate according to claim 2, characterized in that: The catalyst added to the premixing kettle is one or more of potassium hydroxide, sodium hydroxide, sodium methoxide, triethylamine, tributylamine, and triphenyl phosphite; the inhibitor is one or more of hydroquinone, 2,6-di-tert-butyl-p-cresol, phenothiazine, and p-hydroxyanisole; and the temperature of the premixing kettle is 20-40°C.

4. The method for preparing a hydroxyalkyl acrylate according to claim 2, characterized in that: The preheating section temperature of the continuous flow microchannel reactor is 40-65°C, the reaction section temperature is 65-90°C, the reaction pressure is 0.05-0.3MPa, the maintaining section temperature is 80-90°C, and the residence time of the maintaining section is 60-240min; in the primary continuous reaction unit, the molar ratio of acrylic acid monomer to ethylene oxide or propylene oxide is 1:1.2-2.

0.

5. The method for preparing a hydroxyalkyl acrylate according to claim 2, characterized in that: In the refining unit, the temperature of the buffer tank is 30-60°C and the pressure is -0.05-0.05MPa; the absorption tower is an acid absorption tower, concentrated sulfuric acid is used as a catalyst, water is used as an absorption liquid, and the operating temperature of the absorption tower is 40-90°C and normal pressure; the operating temperature of the concentration tower is 95-115°C and the operating pressure is -0.08-0.02MPa; the first distillation tower is operated at negative pressure, and the tower top temperature is 80-105°C, the second distillation tower is operated at negative pressure, and the tower top temperature is 110-125°C, and the third distillation tower is operated at negative pressure, and the tower top temperature is 130-145°C.

6. The method for preparing a hydroxyalkyl acrylate according to claim 2, characterized in that: The reaction temperature of the alkylation kettle of the secondary polymerization unit is 120-160° C., and the operating pressure is 0.05-0.4 MPa.

7. The method for preparing a hydroxyalkyl acrylate according to claim 2, characterized in that: The multifunctional polymerization kettle of the comprehensive treatment unit is used for esterification synthesis of acrylic acid series hydroxyalkyl ester, for end-capping modification of acrylic acid series hydroxyalkyl ester, and for synthesis of polycarboxylic acid mother liquor.

8. The method for preparing a hydroxyalkyl acrylate according to claim 7, characterized in that: When the multifunctional polymerizer of the comprehensive treatment unit is used for esterification synthesis of acrylic acid hydroxyalkyl ester, the by-product ethylene glycol, oligomeric polyethylene glycol or propylene glycol, oligomeric polypropylene glycol concentrate concentrated in the concentration tower, and the heavy components of the third distillation tower are transported into the multifunctional polymerizer, and the solution polymerization is completed by dropwise adding acrylic acid monomers to obtain an acrylic acid hydroxyalkyl ester aqueous solution; before esterification, an inhibitor needs to be added, and the addition amount is 0.3-5‰ of the total amount of dry active matter; p-toluenesulfonic acid is selected as the catalyst, and the amount used is 0.5-3% of the total amount of dry active matter; the esterification temperature is 120-180°C, and the reaction time is 2-4h.

9. The method for preparing a hydroxyalkyl acrylate according to claim 7, characterized in that: When the multifunctional polymerizer of the comprehensive treatment unit is used for end-capping modification of acrylic acid hydroxyalkyl ester, the acrylic acid hydroxyalkyl ester synthesized in the alkylation reactor is delivered to the multifunctional polymerizer through a delivery pump, and an end-capping reaction is carried out by dripping an end-capping agent to obtain an acrylic acid hydroxyalkyl ester end-capped derivative, wherein the end-capping agent is one or more of methyl chloride, acetic anhydride, and benzyl chloride, the reaction temperature is 10-90° C., the reaction time is 2-8 hours, and the catalyst selected for this reaction is a sodium hydroxide or potassium hydroxide solution with a mass fraction of 30-50%, and the amount used is 0.5-5% of the total solid content of the reaction substrate.

10. The method for preparing a hydroxyalkyl acrylate according to claim 7, characterized in that: When the multifunctional polymerization kettle of the comprehensive treatment unit is used to synthesize polycarboxylic acid mother liquor, the esterified acrylic acid hydroxyalkyl ester aqueous solution and functional additives are put into the multifunctional polymerization kettle to synthesize the polycarboxylic acid mother liquor, the functional additives include macromonomers, initiators, chain transfer agents, functional monomers, and water, the macromonomers are one or more of HPEG, TPEG, VPEG, EPEG, and GPEG; the initiator is one or more of 10-30% hydrogen peroxide, ammonium persulfate, and bleaching powder; the chain transfer agent is one or more of thioglycolic acid, mercaptopropionic acid, mercaptoethanol, and sodium methacrylic acid; the functional monomer is one or more of 1-methylallyl acetate, 2-methylallyl acetate, acrylic acid monopolyhydroxyalkyl ester, acrylic acid dipolyhydroxyalkyl ester, acrylic acid, methacrylic acid, and acrylamide; the molar ratio of the macromonomer to the functional monomer is 1:2.5-4.5; the synthesis temperature is 15-60° C., the reaction time is 0.5-4h, and the aging is 0.5-2h.

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