Common knowledge of coating: esterification process of alkyd resin

It is suggested that the esterification process of alkyd resin produced by fatty acid method or alcoholysis method is dehydration by solvent method Because the most basic chemical reaction of alkyd resin is esterification, the water produced in the reaction must be removed in time, so that the esterification can be carried out in depth In the melting process, inert gas is continuously introduced to help stirring, discharge the water vapor generated by esterification reaction and prevent reaction oxidation The solvent method uses organic solvent as azeotropic liquid to help esterification, In the esterification stage, 3% - 5% solvent (mainly xylene) was added When fatty acid is used to produce alkyd resin, polybasic acid is used Shenyang steel structure fireproof coating construction expert punde Building Fire Engineering Co., Ltd Recommended introduction: since its establishment, Shenyang punde Construction Fire Engineering Co., Ltd has cultivated a group of professional construction teams with excellent equipment, rich experience and serious responsibility with advanced and scientific management methods and strict engineering quality assurance and after-sales service system It has undertaken a number of fire system installation projects, which has been praised by customers Every idea and special requirement of you will be fully considered by us and fully realized in the construction technology, which will become the cornerstone of our successful long-term development We are looking forward to your invitation, to provide you with quality services and high-quality technical support! All construction coatings have passed ISO9001 Paint Home News: fatty acid method or alcoholysis method to produce alkyd resin esterification process is to use solvent dehydration Because the most basic chemical reaction of alkyd resin is esterification, the water produced in the reaction must be removed in time, so that the esterification can be carried out in depth In the melting process, inert gas is continuously introduced to help stirring, discharge the water vapor generated by esterification reaction and prevent reaction oxidation In the solvent method, the organic solvent is used as azeotropic liquid to help esterification, and 3% - 5% solvent (mainly xylene) is added in the esterification stage In the process of producing alkyd resin by fatty acid, the solvent is added into polyacid, polyol and fatty acid simultaneously, and the esterification is carried out by heating up, and azeotropic dehydration is carried out The alkyd resin produced by alcoholysis method is to add reflux xylene after the completion of alcoholysis reaction and addition of aniline The reaction temperature of solvent method is easy to control, which can be adjusted by increasing or decreasing the solvent Table 1 Relation between dosage and boiling point solvent dosage /% boiling point / ℃ xylene 3251-260 xylene 4246-251 xylene 7204-210 solvent method is used to produce alkyd resin A steam heated fractionation column is installed on the reactor, and a filler is installed in the column This equipment is good for formula containing low boiling point components, such as benzoic acid (boiling point 249 ℃), glycol (boiling point 198 ℃), if there is no fractionation column, the loss will be too large The two advantages are advantageous to the separation of solvent and water, and speeding up the esterification reaction When the column is heated with steam, the esterified water can be evaporated out, while other alcohols, acids and some solvents can be recycled Note that the temperature of xylene returned to the reactor through the condenser should not be too high, because the solubility of water in xylene will increase at a higher temperature Table 2 solubility temperature of water in xylene / ℃ 25 40 55 70 solubility / (g / 100ml) 0.018 0.06 0.090 0.118 Table 3 solubility temperature of phthalic anhydride in xylene / ℃ 10 25 40 55 70 solubility / (g / 100ml) 0.88 1.50 2.60 4.25 5.85 if more water is brought back to the reactor, it is not conducive to the esterification In the later stage of esterification, the effluent was very little, and xylene brought back to water would prolong the reaction time On the contrary, low temperature will reduce the solubility of phthalic anhydride in xylene, which may cause the condenser to be blocked (Table 3) The xylene returned to the reactor shall be controlled at 25-40 ℃, and the water generated from the reaction shall be collected and measured to understand the extent of esterification The improvement of esterification process of alkyd resin: the traditional process is steam pipe → condenser → water separator → reactor If the improved process is adopted, the temperature of xylene returning to the reactor is 110-125 ℃, which is higher than the azeotropic temperature of xylene water 92 ℃ Due to the high temperature of xylene returned to the reactor, there is little or no water in it, which not only saves energy, but also shortens the dehydration time According to the calculation of the test device, the diesel fuel saving rate of the whole esterification process is 47.3%, the diesel fuel saving rate of the whole alcoholysis and esterification process is 23.6%, and the diesel fuel saving rate of each ton of alkyd resin is 14.2kg Although the input of the packing tower is large at one time, the energy saving effect is obvious, which is worth popularizing Compared with melting method, solvent method has the following advantages ① The resin color is lighter and more uniform, ② the yield is higher, because there is no loss of benzoic acid and polyol, the proportion of polyol and polyol remains basically the same ③ The esterification temperature is relatively low and the esterification reaction cycle is relatively short ④ The temperature is easy to control ⑤ The reactor is easy to clean Home of coatings is specialized in coatings, diatom mud, paint coating, coating technology, fire retardant coating news and coating, diatom mud, paint coating, coating technology, fire retardant coating decoration knowledge and decoration renderings,