Method for synthesizing water-soluble UV monomer without washing

Abstract

The invention relates to the technical field of chemical engineering, in particular to a method for synthesizing a water-soluble UV monomer without washing. The method comprises the following steps: polyethylene glycol polyol, acrylic acid, a catalyst and a polymerization inhibitor are mixed in a solvent, heating reflux is performed for a reaction, and in the reaction process, the solvent and water generated by the reaction are azeotropic to take out water; and after the reaction is finished, adding a neutralizing drying agent into the system, reducing the acid value of the system to below 0.5 mgKOH / g, then adding an adsorbent, filtering, desolventizing under negative pressure, and filtering to obtain the water-soluble UV monomer. By adopting the neutralizing drying agent and the adsorbent, the preparation of the water-soluble UV monomer by direct dry cleaning and neutralizing is realized, and the non-environment-friendly behaviors such as a large amount of wastewater generated by washing with water, alkali and water in the traditional process are avoided. The quality of the synthesized UV reactive diluent can reach the industrial standard, the yield is higher, the recovered solvent can be recycled, the UV reactive diluent is more environment-friendly, energy-saving and efficient, the production cost is reduced, and the UV reactive diluent has a wide market application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of chemical engineering, and in particular to a method for synthesizing a water-soluble UV monomer without washing. Background Art

[0002] Ultraviolet (UV) and electron beam (EB) energy-cured coatings offer excellent appearance, durability, reduced volatile organic compound (VOC) emissions, while facilitating increased productivity and lower costs of curing liquids to solids.

[0003] Monomers are important components of UV and EB curing coatings. They can dissolve and dilute oligomers to adjust the viscosity of the system and improve construction performance; participate in polymerization and curing film formation to adjust the light curing speed; and affect various properties of the cured film such as wear resistance, hardness, flexibility, adhesion, etc.

[0004] Water-soluble monomers can form a mixture with water, which is easy to emulsify under the action of emulsifiers to form emulsions. Compared with non-water-soluble monomers, water-soluble monomers have the following advantages: conventional pure water can be used as the continuous phase, and expensive organic solvents are not required as the dispersed phase, which saves energy and reduces emissions; the particles formed during the polymerization process are uniform in size and have good dispersibility in the emulsion; there will be no problems of organic solvent volatilization and pollution during the production process, which is environmentally friendly.

[0005] At present, most of the UV monomers in the domestic and foreign markets are produced by direct esterification. After the esterification reaction, the products are finally obtained after water washing, alkali washing, extraction, water washing, vacuum removal of solvents, and filtration. The production of 1 ton of monomer products generates about 1.5-2.5 tons of wastewater, the wastewater treatment cost is high, and a large amount of acrylic acid raw materials are consumed, which cannot meet environmental protection requirements.

[0006] At the same time, due to the hydrophilicity or water solubility of the water-soluble UV monomer, the water-soluble UV monomer will dissolve in water during the water washing process, resulting in a very low yield. In order to increase the yield, saturated salt water is needed for washing, which not only increases the production cost, but also generates a large amount of salt-containing wastewater, greatly increasing the production cost and reducing the yield. Summary of the invention

[0007] In view of this, the technical problem to be solved by the present invention is to provide a method for synthesizing water-soluble UV monomers without water washing, thereby avoiding the steps of a large number of water washing, alkali washing and then water washing in the traditional process and reducing the amount of waste water.

[0008] To achieve the above object, the present invention provides a method for synthesizing a water-soluble UV monomer without washing, comprising the following steps:

[0009] Mixing polyethylene glycol polyol, acrylic acid, a catalyst and a polymerization inhibitor in a solvent, heating and refluxing to react, during which the solvent and water generated by the reaction azeotropically remove the water;

[0010] After the reaction is completed, a neutralizing desiccant is added to the system to reduce the acid value of the system to below 0.5 mgKOH / g, and then an adsorbent is added for filtration. After negative pressure desolventization and filtration, a water-soluble UV monomer is obtained.

[0011] Optionally, the polyethylene glycol polyol is selected from one or more of methoxy polyethylene glycol, polyethylene glycol, ethoxylated bisphenol A, and ethoxylated trimethylolpropane.

[0012] The present invention has no particular limitation on the above-mentioned catalyst, and it can be a general catalyst suitable for the present reaction, including but not limited to one or more of metal inorganic salts and Lewis acids. The metal inorganic salt can be selected from one or more of sodium hydrogen sulfate monohydrate, ammonium ferric disulfate dodecahydrate, etc. The Lewis acid can be selected from one or more of ferric chloride hexahydrate, tin dichloride dihydrate, etc.

[0013] The present invention has no particular limitation on the above-mentioned polymerization inhibitor, which can be a general polymerization inhibitor suitable for the present reaction, including but not limited to p-hydroxyanisole.

[0014] The present invention has no particular limitation on the above-mentioned solvent, and it can be any general water-miscible solvent suitable for the present reaction, including but not limited to one or more of cyclohexane, n-heptane, toluene, etc.

[0015] The molar ratio of the total amount of hydroxyl groups in the polyethylene glycol polyol to the acrylic acid is preferably 1:(1.1-1.3).

[0016] That is, when the polyethylene glycol polyol is a monofunctional polyol, the molar ratio of the polyethylene glycol polyol to acrylic acid is preferably 1:1.1-1:1.3; when the polyethylene glycol polyol is a difunctional polyol, the molar ratio of the polyethylene glycol polyol to acrylic acid is preferably 1:2.2-2.4; when the polyethylene glycol polyol is a trifunctional polyol, the molar ratio of the polyethylene glycol polyol to acrylic acid is preferably 1:3.3-3.6. The proportion of the catalyst in the theoretical finished product is preferably 0.03%-0.07%; the content of the inhibitor is preferably between 300ppm-600ppm of the theoretical finished product.

[0017] The present invention does not limit the temperature of the reflux reaction, which is determined according to the boiling point of the solvent, and is generally 80-100°C. In some specific embodiments of the present invention, the reaction is started at 80°C for reflux reaction, and the reaction system is controlled not to exceed 96°C or not to exceed 97°C to avoid the occurrence of side reactions.

[0018] The present invention does not limit the time for the above reflux reaction. The reaction is considered complete when no water flows out of the system. Preferably, the reaction is continued for half an hour after no water flows out and then stopped.

[0019] The above reaction was carried out in an air atmosphere.

[0020] During the reaction, the solvent and the water generated by the reaction are azeotropic, and the esterification water is taken out. After the reaction is completed, the acid value is tested, and if it is qualified, it is transferred to the water washing kettle for the deacidification process.

[0021] Specifically, the acid value of the system is tested, the amount of the neutralizing desiccant to be used is calculated, and the neutralizing desiccant is used to reduce the acid value of the system to below 0.5 mgKOH / g.

[0022] The test results show that reducing the acid value of the system to below 0.5 mgKOH / g can ensure that the acid value of the monomer is within a reasonable range and avoid acid corrosion due to high acid value during construction.

[0023] The present invention has no particular limitation on the neutralizing desiccant, which may be an alkaline compound well known to those skilled in the art, including but not limited to one or more of sodium bicarbonate, sodium carbonate, potassium bicarbonate, potassium carbonate, and the like.

[0024] Then add adsorbent to the system for filtration to remove salt substances and micropolymers in the system.

[0025] The adsorbent is preferably one or more of adsorption-type magnesium aluminum silicate, diatomaceous earth, activated carbon, silica gel, alumina, polyacrylamide, calcium-based bentonite, and the like.

[0026] The amount of the adsorbent added is preferably 2%-5% of the mass of the finished product.

[0027] Then, the solution is desolventized under negative pressure and filtered to obtain the water-soluble UV monomer, i.e. the finished product of UV active diluent.

[0028] The present invention has no particular limitation on the negative pressure desolvation method, which may be a method well known to those skilled in the art. The present invention may be carried out in a thin film evaporator or a kettle distiller.

[0029] In some specific embodiments of the present invention, the method specifically comprises the following steps:

[0030] Mix polyethylene glycol polyol, acrylic acid, catalyst, inhibitor and solvent in an esterification kettle and heat to reflux. After the reaction is completed, cool down to below 25°C with cooling water, transfer all materials to a dry cleaning kettle, test the acid value of the system, and calculate the weight of the added dry neutralizer. Stir in the kettle, ventilate, slowly add dry neutralizer, and after standing for a period of time, all materials enter a closed filter containing an adsorbent, and after filtration, enter a desolventizing buffer tank, use negative pressure for desolventizing, and after the solvent is removed, use a filter press to filter the finished product, and package it after passing the test.

[0031] Compared with the prior art, the present invention provides a method for synthesizing a water-soluble UV monomer without washing, comprising the following steps: mixing polyethylene glycol polyol, acrylic acid, a catalyst and an inhibitor in a solvent, heating and refluxing to react, during the reaction, the solvent and the water generated by the reaction are azeotropically taken out of the water; after the reaction is completed, a neutralizing desiccant is added to the system to reduce the acid value of the system to less than 0.5 mgKOH / g, then an adsorbent is added for filtration, and a water-soluble UV monomer is obtained after negative pressure desolventizing and filtration.

[0032] The present invention realizes direct dry cleaning and neutralization to prepare water-soluble UV monomers by adopting neutralizing desiccants and adsorbents, avoiding the environmentally unfriendly behaviors such as large-scale salt water washing, alkali washing, and then salt water washing in the traditional process, which generates a large amount of waste water. The synthesized UV active diluent can meet the industry standard in quality and has a high yield, and the recovered solvent can be recycled. This new treatment method can avoid the traditional energy-consuming methods such as salt water washing, alkali washing, and then salt water washing, and obtain high-quality UV active diluent, which is more environmentally friendly, energy-saving, and efficient, and reduces production costs, and has a wide market application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The present invention provides a flow chart for the non-washing synthesis of water-soluble UV monomers. DETAILED DESCRIPTION

[0034] In order to further illustrate the present invention, the following is a detailed description in conjunction with the embodiments. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the invention.

[0035] All raw materials of the present invention have no particular limitation on their sources, and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0036] Example 1 Monofunctional water-washable UV monomer MPEG350A (methoxy polyethylene glycol (350) acrylate)

[0037] 1. Synthesis process:

[0038] Accurately weigh 1050g of methoxypolyethylene glycol 350, 0.4g of p-hydroxyanisole, 300g of cyclohexane, 240g of acrylic acid, and 42g of sodium hydrogen sulfate tetrahydrate, add them into the esterification kettle, start stirring, ventilate, slowly heat to 80°C and start reflux, and finally the reaction temperature can reach 100°C; until no water flows out, react for another half an hour, and cool down.

[0039] 2. Dry cleaning process:

[0040] Put the monomer mixture obtained by the above esterification reaction into a dry cleaning bottle with stirring and ventilation functions, weigh it, test the acid value, and calculate the amount of neutralizer (sodium bicarbonate or sodium carbonate) added. Stir, ventilate, use cooling water to cool down the material temperature in the dry cleaning bottle to below 25°C, and slowly add the neutralizer. Let it stand for half an hour, use a tank pressure filter, add diatomaceous earth, activated carbon, calcium-based bentonite and other adsorbents, filter out the sodium salt, and filter out the material for desolventizing.

[0041] 3. Desolventizing process:

[0042] Ventilate, stir, slowly raise the temperature to desolventize, the recovered solvent can be used next time. After no more solvent comes out, take samples for testing, and filter if the residual solvent and water content are qualified.

[0043] 1115 g of product was obtained with a yield of 92%, a residual solvent of 330 ppm, an acid value of 0.36 mgKOH / g, a color number of 30 APHA, and a viscosity of 23 cps / 25°C.

[0044] Example 2 Bifunctional water-washable UV monomer PEG (600) DA (polyethylene glycol 600 diacrylate)

[0045] 1. Synthesis process:

[0046] Accurately weigh 1200g of polyethylene glycol 600, 0.5g of p-hydroxyanisole, 300g of cyclohexane, 320g of acrylic acid, and 53g of ferric chloride hexahydrate, add them into the esterification kettle, start stirring, ventilate, slowly heat to 80°C and start reflux, and finally the reaction temperature can reach 100°C; until no water flows out, react for another half an hour, and cool down.

[0047] 2. Dry cleaning process:

[0048] Put the monomer mixture obtained by the above esterification reaction into a dry cleaning bottle with stirring and ventilation functions, weigh it, test the acid value, and calculate the amount of neutralizer (sodium bicarbonate or sodium carbonate) added. Stir, ventilate, use cooling water to cool down the material temperature in the dry cleaning bottle to below 25°C, and slowly add the neutralizer. Let it stand for half an hour, use a tank pressure filter, add diatomaceous earth, activated carbon, calcium-based bentonite and other adsorbents, filter out the sodium salt, and filter out the material for desolventizing.

[0049] 3. Desolventizing process:

[0050] Ventilate, stir, slowly raise the temperature to desolventize, the recovered solvent can be used next time. After no more solvent comes out, take samples for testing, and filter if the residual solvent and water content are qualified.

[0051] 1117 g of product was obtained with a yield of 93%, a residual solvent of 420 ppm, an acid value of 0.33 mgKOH / g, a color number of 28 APHA, and a viscosity of 93 cps / 25°C.

[0052] Example 3 Bifunctional water-washable UV monomer BPA30EODA (30-ethoxylated bisphenol A diacrylate)

[0053] 1. Synthesis process:

[0054] Accurately weigh 1548g 30-ethoxylated bisphenol A, 0.3g p-hydroxyanisole, 400g cyclohexane, 172g acrylic acid, and 66g ferric chloride hexahydrate, add them into the esterification kettle, start stirring, ventilate, slowly heat to 80°C and start reflux, and finally the reaction temperature can reach 97°C; until no water flows out, react for another half an hour, and cool down.

[0055] 2. Dry cleaning process:

[0056] Put the monomer mixture obtained by the above esterification reaction into a dry cleaning bottle with stirring and ventilation functions, weigh it, test the acid value, and calculate the amount of neutralizer (sodium bicarbonate or sodium carbonate) added. Stir, ventilate, use cooling water to cool down the material temperature in the dry cleaning bottle to below 25°C, and slowly add the neutralizer. Let it stand for half an hour, use a tank pressure filter, add diatomaceous earth, activated carbon, calcium-based bentonite and other adsorbents, filter out the sodium salt, and filter out the material for desolventizing.

[0057] 3. Desolventizing process:

[0058] Ventilate, stir, slowly raise the temperature to desolventize, the recovered solvent can be used next time. After no more solvent comes out, take samples for testing, and filter if the residual solvent and water content are qualified.

[0059] 1540 g of product was obtained with a yield of 93%, a residual solvent of 310 ppm, an acid value of 0.33 mgKOH / g, a color number of 35 APHA, and a viscosity of 630 cps / 25°C.

[0060] Example 4 Multifunctional water-washable UV reactive diluent TMP15EOTA (15-ethoxylated trimethylolpropane triacrylate)

[0061] 1. Synthesis process:

[0062] Accurately weigh 956 g of 15-ethoxylated trimethylolpropane, 0.4 g of p-hydroxyanisole, 300 g of cyclohexane, 244 g of acrylic acid, and 58 g of ferric chloride hexahydrate, add them into an esterification kettle, start stirring, ventilate, slowly heat to 80°C and start reflux. The final esterification temperature does not exceed 97°C. After no water flows out of the reaction, extend the esterification for half an hour.

[0063] 2. Dry cleaning process:

[0064] Put the monomer mixture obtained by the above esterification reaction into a dry cleaning bottle with stirring and ventilation functions, weigh it, test the acid value, and calculate the amount of neutralizer (sodium bicarbonate or sodium carbonate) added. Stir, ventilate, use cooling water to cool down the material temperature in the dry cleaning bottle to below 25°C, and slowly add the neutralizer. Let it stand for half an hour, use a tank pressure filter, add diatomaceous earth, activated carbon, calcium-based bentonite and other adsorbents, filter out the sodium salt, and filter out the material for desolventizing.

[0065] 3. Desolventizing process:

[0066] Ventilate, stir, slowly raise the temperature to desolventize, the recovered solvent can be used next time. After no more solvent comes out, take samples for testing, and filter if the residual solvent and water content are qualified.

[0067] 908 g of product was obtained with a yield of 95%, a residual solvent of 270 ppm, an acid value of 0.4 mgKOH / (mg / g), a color number of 31 APHA, and a viscosity of 145 cps / 25°C.

[0068] Example 5 PEG400DA (polyethylene glycol 400 diacrylate)

[0069] 1. Synthesis process:

[0070] Accurately weigh 12000Kg PEG400, 6Kg p-hydroxyanisole, 2500Kg cyclohexane, 3760Kg acrylic acid, and 470Kg ferric chloride hexahydrate, add them into the esterification kettle, start stirring, ventilate, slowly heat to 78°C and start reflux, and finally maintain the temperature at 96°C. After 11 hours of reaction, no water flows out, extend the esterification for half an hour, and cool down.

[0071] 2. Dry cleaning process:

[0072] After the esterification in the esterification kettle is completed, the temperature is lowered to below 50°C and transferred to the dry cleaning kettle. The acid value of the detection system is 35mgKOH / g, which is converted into an acid content of 4.515%. The amount of neutralizer (sodium bicarbonate) added is calculated, stirring is started, cooling water is used to cool the material temperature in the dry cleaning bottle to below 20°C, air is passed, neutralizer is slowly added, stirring for 1 hour, material is discharged from the bottom valve, and a closed filter is used to add diatomaceous earth, magnesium aluminum silicate, calcium-based bentonite and other mixed adsorbents, filter sodium salt, and filter out the material for desolventizing.

[0073] 3. Desolventizing process:

[0074] Using kettle distillation, the recovered solvent can be used next time. At the later stage of desolventization, sampling and testing are carried out. If the residual solvent is less than 500ppn, it is qualified. It is filtered using a plate and frame filter press and packaged after it is clarified and transparent.

[0075] The product was obtained in an amount of 14330 kg with a yield of 94%, an acid value of 0.25 mg KOH / g, a color number of 30 APHA, a residual solvent of 280 ppm, and a viscosity of 56 cps / 25°C.

[0076] illustrate:

[0077] The PEG400DA synthesized by the existing technology is easily soluble in water. According to the traditional production process, it needs to be washed with saturated salt water and high-concentration alkali solution. Due to the neutralization of water washing and alkali washing, part of the finished product will be washed away, and the final yield is generally around 80%. The present invention uses a dry cleaning process, and the yield can reach more than 94%, which is much higher than the yield of the traditional monomer treatment method. The dry cleaning process can not only improve the yield, but also be more environmentally friendly, energy-saving and efficient.

[0078] The above examples show that the preparation method of the aqueous UV active diluent provided by the present invention adopts the dry cleaning process for the first time, which reduces the production cost. In addition to the esterified water (which can be used as the mother liquor of the water reducing agent), there is no wastewater discharge, which is a more environmentally friendly, efficient and energy-saving treatment method. It will bring great changes to the production of aqueous UV active diluents, change the concept of active diluent production with a lot of wastewater, and achieve the purpose of no water washing and alkali washing. It is a new process of energy saving, consumption reduction, environmental protection and high efficiency, which greatly reduces the production cost of monomers and improves market competitiveness.

[0079] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for synthesizing a water-soluble UV monomer without washing, comprising the following steps: Mixing polyethylene glycol polyol, acrylic acid, a catalyst and a polymerization inhibitor in a solvent, heating and refluxing to react, during which the solvent and water generated by the reaction azeotropically remove the water; After the reaction is completed, a neutralizing desiccant is added to the system to reduce the acid value of the system to below 0.5 mgKOH / g, and then an adsorbent is added for filtration. After negative pressure desolventization and filtration, a water-soluble UV monomer is obtained.

2. The method according to claim 1, characterized in that: The polyethylene glycol polyol is selected from one or more of methoxy polyethylene glycol, polyethylene glycol, ethoxylated bisphenol A, and ethoxylated trimethylolpropane.

3. The method according to claim 1, characterized in that: The catalyst is selected from one or more of metal inorganic salts and Lewis acids.

4. The method according to claim 1, characterized in that The polymerization inhibitor is selected from p-hydroxyanisole.

5. The method according to claim 1, characterized in that: The solvent is selected from one or more of cyclohexane, n-heptane and toluene.

6. The method according to claim 1, characterized in that The heating reflux temperature is 80-100°C.

7. The method according to claim 1, characterized in that The neutralizing desiccant is selected from one or more of sodium bicarbonate, sodium carbonate, potassium bicarbonate and potassium carbonate.

8. The method according to claim 1, characterized in that: The adsorbent is selected from one or more of adsorption-type magnesium aluminum silicate, diatomaceous earth, activated carbon, silica gel, alumina, polyacrylamide, and calcium-based bentonite.

9. The method according to claim 1, characterized in that: The molar ratio of the total amount of hydroxyl groups in the polyethylene glycol polyol to the acrylic acid is 1:(1.1-1.3).

Images