Method for improving adhesion performance of HMMM resin by means of methylal

Abstract

Disclosed is a method for improving the adhesion performance of an HMMM resin by means of methylal. The method comprises the following steps: S1, raw material preparation: preparing 9.36-12.48 mol of methanol, 0.408-4.08 mol of a catalyst promoter and 0.408-0.816 mol of hexamethylol melamine; and S2, preparing an HMMM resin: S2-1, sequentially adding methanol, the catalyst promoter and hexamethylol melamine into a 1000 mL reaction kettle with a stirrer and a reflux condenser, performing heating under alkaline conditions to evaporate off the residual methylal, methanol and water, and performing reduced pressure distillation to obtain the HMMM resin. According to the present invention, the reaction of methylal with water to generate hexamethoxymethyl melamine is promoted by the combined action of a catalyst promoter A and a catalyst promoter B, thereby improving the water absorption effect of the methylal solution; moreover, a magnetic cobalt oxide can be fully mixed with methanol when a magnetic cation exchange resin is used, further accelerating the etherification reaction, and improving the etherification effect, and thereby effectively improving the adhesion performance of an HMMM resin.

Description

A method for improving the bonding properties of HMMM resin by methylal Technical Field

[0001] The present invention relates to the technical field of resin preparation, and in particular to a method for improving the adhesive properties of HMMM resin by using methylal. Background Art

[0002] HMMM resin is the abbreviation for hexamethoxymethyl melamine formaldehyde resin, also known as 560 resin. HMMM resin appears as a colorless or light yellow, transparent, viscous liquid with excellent heat resistance, water resistance, and good compatibility with resins. HMMM resin is low in toxicity and can be used as a crosslinker in water-based acrylic and water-based epoxy resin adhesives to improve the adhesive's water resistance and heat resistance. In addition, HMMM resin can also be used to prepare coatings, crosslinking agents, amino resins, and other materials.

[0003] 0003. As the main adhesive of rubber, it is used in combination with a methylene acceptor to bond rubber to skeleton materials such as steel wire. When methanol and hexahydroxymethyl melamine are used to react to prepare HMMM resin through etherification, methylal is added at the same time (methylal refers to a compound generated by the dehydration of formaldehyde and methanol, which can "absorb" the water generated in the etherification reaction and has no other effect on the etherification reaction itself). Through the balanced reaction between the added methylal and methanol, formaldehyde and water, the free water generated in the etherification reaction system is reduced, so that the etherification reaction proceeds in a direction that is favorable for the formation of etherification products, and the reduction of water can also reduce the condensation between molecules. The above method for preparing HMMM resin can improve the adhesive properties of HMMM resin to a certain extent, but the improvement effect is limited. Technical issues

[0004] The methods for preparing HMMM resin in the prior art are not effective in improving the adhesive properties of the HMMM resin. Technical Solutions

[0005] To solve the above technical problems, the present invention provides a method for improving the bonding performance of HMMM resin by using methylal.

[0006] 0006. The technical solution of the present invention is: a method for improving the bonding performance of HMMM resin by methylal, comprising the following steps:

[0007] 0007.S1, Raw material preparation

[0008] 0008. Prepare 9.36-12.48 mol of methanol, 0.408-4.08 mol of a catalyst promoter, and 0.408-0.816 mol of hexamethylolmelamine; the catalyst promoter includes a catalyst promoter A and a catalyst promoter B; wherein the catalyst promoter A comprises, by mass percentage, 5-10% of ammonium trifluoromethanesulfonate, 1-3% of hydrogenated rosin toluene, and the remainder of a mixed solution; the mixed solution is prepared from a methylal solution and anhydrous ethanol in a volume ratio of 1:1-2; the catalyst promoter B is composed of the catalyst promoter A and 3.5-5% by mass of the catalyst promoter A in magnetic cobalt oxide;

[0009] 0009.S2. Preparation of HMMM resin

[0010] 0010.S2-1. Add methanol, catalyst promoter and hexamethylolmelamine in sequence into a 1000 mL reactor equipped with a stirrer and a reflux condenser;

[0011] 0011.S2-2. Heat the reactor to 45-55°C. After the contents become transparent, keep the mixture warm and continue stirring for 40-50 minutes. Then, add alkali solution to adjust the pH to 8-9. Heat the mixture to remove the remaining methylal, methanol, and water. When the temperature reaches 85-95°C, start the vacuum system and continue heating. When the temperature reaches 105-115°C, continue stirring and keep the mixture warm for 25-35 minutes. Then, cool the mixture to 85-95°C, filter, and distill under reduced pressure to obtain HMMM resin.

[0012] 0012. Description: Ammonium trifluoromethanesulfonate can effectively promote the reaction of methylal and water to form hexamethoxymethylmelamine in the etherification reaction, thereby improving the water absorption effect of the methylal solution, and can reduce the influence of trifluoromethanesulfonic acid on the etherification reaction without affecting the water absorption efficiency of methylal; hydrogenated rosin toluene has a certain solubility and stability, which can promote the process of methylal and water reacting to form hexamethoxymethylmelamine, thereby improving the water absorption effect of the methylal solution; and the magnetic cobalt oxide contained in the catalyst aid B can be fully mixed with methanol and other organic matter during the magnetic cation exchange resin, further accelerating the etherification reaction, enhancing the etherification effect and thus improving the viscosity of the HMMM resin.

[0013] 0013. Further, in step S2-1, the step of adding the methanol, the catalyst aid and the hexamethylolmelamine is:

[0014] 0014.S2-1-1. Add 1 / 4-3 / 4 of methanol and hexamethylolmelamine to the reactor, and add catalytic aid A accounting for 5-5.5% of the mass of hexamethylolmelamine;

[0015] 0015.S2-1-2. Raise the temperature of the reactor to 35-40°C, continue to add 1 / 4-3 / 4 of methanol and the remaining amount of catalyst promoter A, keep warm for 25-30 minutes and stir to mix, then raise the temperature to 60-70°C, add the remaining amount of methanol and the entire amount of catalyst promoter B, keep warm for 35-50 minutes and stir to mix;

[0016] 0016. Note: First adding the catalyst A in the above proportion and then adding methanol and catalyst B after heating can make the magnetic cobalt oxide better dispersed in methylal, further improve the etherification effect, and thus improve the effect of methylal on improving the viscosity of HMMM resin.

[0017] 0017. Further, in step S1, the preparation method of the catalyst aid A is:

[0018] 0018.1) Add hydrogenated rosin toluene and ammonium trifluoromethanesulfonate to a stirred tank and disperse under vacuum at 95-105°C for 2-2.5 hours to obtain a premix, which is set aside.

[0019] 0019.2) Purifying the methylal solution for 2-3 hours to a purity of 99.1-99.9%, then mixing the methylal solution with anhydrous ethanol in a suitable proportion to obtain a mixed solution for later use;

[0020] 0020.3) The mixed solution obtained in step 2) is first added to the reactor, and the premix obtained in step 1) is treated with an atomizer to a particle size of 2-3 μm. The premix is ​​then introduced into the reactor at a rate of 30-50 mL / min at a temperature of 55-60°C for 50-60 minutes. The temperature is raised to 75-80°C, and then the premix is ​​continued to be introduced for 30-40 minutes. During the introduction process, the mixture is stirred and mixed at a speed of 120-150 r / min. Finally, the temperature is lowered to 20-25°C to obtain catalytic aid A.

[0021] 0021. Description: Dispersing hydrogenated rosin toluene and ammonium trifluoromethanesulfonate under vacuum before atomizing can effectively promote the uniform dispersion of the premix and improve its quality and stability. Atomization can increase the surface area of ​​the material, improve the reaction rate and adsorption performance, and is also beneficial to the uniform dispersion and stability of the material. Purifying the methylal solution and then preparing the catalyst A can further enhance the promoting effect of methylal on the etherification reaction. At the same time, ammonium trifluoromethanesulfonate also has the acidity of trifluoromethanesulfonic acid and has a smaller inhibitory effect on the etherification reaction, which effectively provides an acidic environment in the preparation process of HMMM resin, reduces the additional addition of acid solution, and reduces the preparation cost.

[0022] 0022. Furthermore, in step 2), the purification method is as follows: mixing the methylal solution and the impurity remover in a mass ratio of 7-10:25-35 and stirring at 55-60°C for 25-35 minutes, then standing for 1-1.5 hours, ultrasonically adsorbing the upper layer of the standing liquid using an adsorbent at an ultrasonic frequency of 35-40kHz and an ultrasonic power of 700-800W, then cooling the standing liquid to 20-25°C, further separating and removing impurities from the upper layer, and distilling the bottom mixed liquid at room temperature and pressure using a distillation tower to obtain a purified methylal solution; the ultrasonic adsorption time is 15-20 minutes; the operating pressure of the distillation tower is 100-110kPa; the adsorbent is selected from any one of molecular sieves and activated carbon;

[0023] 0023. Note: The above steps can efficiently purify the methylal solution, thereby effectively improving the performance of methylal itself and further improving the promoting effect of methylal on the bonding performance of HMMM resin.

[0024] 0024. Furthermore, the impurity remover comprises, by mass percentage, 20-25% of oxalic acid, 5-10% of composite gel and the balance of ammonium oxalate;

[0025] 0025. Description: The impurity remover with the above ingredients can effectively remove impurities in the methylal solution while having little impact on the performance of the methylal.

[0026] 0026. Furthermore, the composite gel is a modified composite gel obtained after modification; the preparation method of the modified composite gel is:

[0027] 0027. Using 10% hydrochloric acid to adjust the pH to 2-3, sodium methyl silicate and hydrogel are mixed in a reactor at a molar ratio of 1:1.5-3 and subjected to polymerization reaction to obtain a precursor solution; ethanol and deionized water are prepared in sequence at a mass ratio of precursor solution: ethanol: deionized water of 2.5-4.5:5-7:5-7 and added to the reactor, heated to 85-90°C, stirred at this temperature for 25-35 minutes, and then aged at 20-25°C for 2-3 days; finally, the obtained mixture is vacuum dried to obtain a modified composite gel; wherein the drying temperature is 50-60°C and the drying time is 1-2 hours;

[0028] 0028. Description: Hydrogel is an extremely hydrophilic three-dimensional network structure gel that swells rapidly in water and can retain a large volume of water in this swollen state without dissolving. Therefore, it has strong water absorption performance. Polymerizing silicic acid molecules with hydrogel to generate a copolymer containing both silicic acid and hydrogel segments can enable the composite gel to have the ability to absorb water while having the effect of removing impurities, thereby further improving the water absorption effect and achieving the purpose of improving the bonding performance of HMMM resin.

[0029] 0029. Further, the ammonium trifluoromethanesulfonate is modified to obtain modified ammonium trifluoromethanesulfonate;

[0030] 0030. The modified ammonium trifluoromethanesulfonate is prepared by mixing benzenesulfonic acid crystals: plasticizer: ammonium trifluoromethanesulfonate: polyvinyl alcohol in a mass ratio of 1-1.2:0.4-0.6:2-3:3-5;

[0031] The modified ammonium trifluoromethanesulfonate is prepared by drying benzenesulfonic acid crystals in an oven at 40-45°C, then mixing the dried benzenesulfonic acid crystals with a plasticizer and heating the mixture to a molten state to obtain a mixed solution M; and preparing ammonium trifluoromethanesulfonate and polyvinyl alcohol in a certain proportion and mixing them to obtain a mixed solution N.

[0032] 0032. The mixed liquid M is extruded into particles with a particle size of 1-3 μm by an extruder, and the particles are placed in a cooling device at a temperature of -5 to 5°C to cool and shape them. Finally, the mixed liquid N is sprayed on the surface of the particles, stirred evenly, and placed in a room temperature dryer to dry for later use;

[0033] 0033. Description: The above method can effectively increase the specific surface area of ​​the modified ammonium trifluoromethanesulfonate by first plasticizing the benzenesulfonic acid crystals and then spraying ammonium trifluoromethanesulfonate on the surface of the benzenesulfonic acid particles, further enhancing the promoting effect of the modified ammonium trifluoromethanesulfonate in the etherification process of methylal, thereby enhancing the absorption capacity of the water generated in the etherification reaction, reducing the free water generated in the etherification reaction system, and significantly improving the performance of the HMMM resin.

[0034] 0034. Further, the plasticizer is any one of epoxy vegetable oil, trimethoxysilane, and polyethylene glycol;

[0035] 0035. Note: The above plasticizer can promote the melting of benzenesulfonic acid crystals, thereby improving the preparation efficiency of particles.

[0036] 0036. Further, the alkali solution is any one of a sodium hydroxide solution with a mass fraction of 10-15% and a potassium hydroxide solution with a mass fraction of 10-15%;

[0037] 0037. Note: The above-mentioned alkali solution will not produce any harmful substances during use and will not pollute the environment; it can efficiently change the pH value and further improve the treatment effect. Beneficial effects

[0038] (1) The present invention promotes the reaction of methylal with water to generate hexamethoxymethyl melamine through catalytic aids A and B, thereby improving the water absorption effect of the methylal solution. At the same time, the magnetic cobalt oxide can be fully mixed with methanol during the magnetic cation exchange resin, further accelerating the etherification reaction and enhancing the etherification effect, thereby effectively improving the bonding properties of the HMMM resin.

[0039] 0039. (2) The present invention prepares a modified composite gel by utilizing the polymerization reaction of silica molecules and hydrogel, so that the modified composite gel has the effect of removing impurities from the methylal solution and at the same time utilizes the three-dimensional network structure of the hydrogel to rapidly swell in water and has strong water absorption performance in this swollen state, further enhancing the promoting effect on the etherification reaction, thereby improving the adhesion performance of the HMMM resin.

[0040] 0040. (3) The present invention plasticizes benzenesulfonic acid crystals and then sprays ammonium trifluoromethanesulfonate on the surface of benzenesulfonic acid particles, which can effectively increase the specific surface area of ​​modified ammonium trifluoromethanesulfonate, further enhancing the role of modified ammonium trifluoromethanesulfonate in promoting the etherification of methylal. In addition, the use of benzenesulfonic acid crystals as a carrier can provide a strong acidic environment, which helps to increase the activity of polyvinyl alcohol, thereby promoting the diffusion of ammonium trifluoromethanesulfonate and significantly improving the bonding performance of HMMM resin. Best Mode for Carrying Out the Invention

[0041] Example 19: A method for improving the adhesive properties of HMMM resin by using methylal, comprising the following steps:

[0042] 0042.S1, Raw material preparation

[0043] Prepare 10.92 mol of methanol, 2.03 mol of a catalyst promoter, and 0.627 mol of hexamethylolmelamine; the catalyst promoter comprises catalyst promoter A and catalyst promoter B; wherein catalyst promoter A comprises, by mass percentage, 7% ammonium trifluoromethanesulfonate, 2% hydrogenated rosin toluene, and the remainder a mixed solution; the mixed solution is prepared from a methylal solution and anhydrous ethanol in a volume ratio of 1:1.5; catalyst promoter B comprises catalyst promoter A and 4.3% magnetic cobalt oxide, which accounts for 4.3% of catalyst promoter A by mass;

[0044] 0044. In step S1, the preparation method of the catalyst aid A is:

[0045] 0045.1) Add hydrogenated rosin toluene and modified ammonium trifluoromethanesulfonate to a stirred tank and disperse under vacuum at 100°C for 2.3 hours to obtain a premix, which is set aside.

[0046] 0046.2) Purifying the methylal solution for 2.5 hours to a purity of 99.5%, then mixing the methylal solution with anhydrous ethanol in a suitable proportion to obtain a mixed solution for later use;

[0047] 0047.3) The mixed solution obtained in step 2) was first added to a reactor, and the premix obtained in step 1) was atomized using an atomizer to a particle size of 2.5 μm. The premix was then introduced into the reactor at a rate of 40 mL / min at 58°C for 55 minutes. The temperature was raised to 78°C and continued to be introduced for 35 minutes. During the addition, the mixture was stirred at a rate of 135 rpm. Finally, the temperature was lowered to 23°C to obtain catalytic promoter A.

[0048] 0048.S2. Preparation of HMMM resin

[0049] 0049.S2-1. Add methanol, catalyst promoter, and hexamethylolmelamine sequentially into a 1000 mL reactor equipped with a stirrer and a reflux condenser;

[0050] 0050. The steps of adding methanol, catalyst promoter and hexamethylolmelamine are as follows:

[0051] 0051.S2-1-1. Add 2 / 4 of methanol and hexamethylolmelamine to the reactor, and add catalytic aid A in an amount of 5.3% by weight of the hexamethylolmelamine;

[0052] 0052.S2-1-2. Raise the temperature of the reactor to 37°C, add 1 / 4 of the methanol and the remaining amount of catalyst promoter A, keep warm for 28 minutes and stir to mix thoroughly. Then, raise the temperature to 60-70°C, add the remaining amount of methanol and the entire amount of catalyst promoter B, keep warm for 43 minutes and stir to mix thoroughly.

[0053] 0053.S2-2. Heat the reactor to 50°C. After the contents become transparent, insulate and continue stirring for 45 minutes. Then, add alkali solution to adjust the pH to 8.5. Heat and evaporate the remaining methylal, methanol, and water. When the temperature reaches 90°C, start the vacuum system and continue heating. When the temperature reaches 110°C, continue stirring and insulate for 30 minutes. Then, cool to 90°C, filter, and distill under reduced pressure to obtain HMMM resin.

[0054] 0054. In step 2), the purification method is as follows: methylal solution: impurity remover in a mass ratio of 8:30 is mixed and stirred at 58° C. for 30 minutes, followed by standing for 1.3 hours. The upper layer of the standing solution is subjected to ultrasonic adsorption treatment using an adsorbent at an ultrasonic frequency of 37 kHz and an ultrasonic power of 750 W. The standing solution is then cooled to 22° C., the upper layer of impurities is further separated and removed, and the bottom mixed solution is distilled at room temperature and pressure using a distillation tower to obtain a purified methylal solution. The ultrasonic adsorption time is 18 minutes. The operating pressure of the distillation tower is 105 kPa. The adsorbent is activated carbon. The impurity remover comprises, by mass percentage, 23% oxalic acid, 7% composite gel, and the remainder ammonium oxalate.

[0055] 0055. The composite gel is a modified composite gel obtained after modification; the preparation method of the modified composite gel is:

[0056] 0056. The pH value was adjusted to 2.5 using hydrochloric acid having a mass concentration of 10%, and sodium methyl silicate and hydrogel were mixed in a reactor at a molar ratio of 1:2.2 and subjected to polymerization reaction to obtain a precursor solution; ethanol and deionized water were prepared in sequence at a mass ratio of precursor solution: ethanol: deionized water of 3.5:6:6 and added to the reactor, heated to 87°C, kept warm and stirred for 30 minutes, and then aged at 23°C for 2.5 days; finally, the mixed solution obtained above was vacuum dried to obtain a modified composite gel; wherein, the drying temperature was 55°C and the drying time was 1.5 hours.

[0057] 0057. Among them, the modified ammonium trifluoromethanesulfonate is prepared by mixing benzenesulfonic acid crystals: plasticizer: ammonium trifluoromethanesulfonate: polyvinyl alcohol in a mass ratio of 1.1:0.5:2.5:4;

[0058] 0058. The preparation method of modified ammonium trifluoromethanesulfonate is as follows: first, benzenesulfonic acid crystals are placed in an oven at a temperature of 43°C for drying, and then the dried benzenesulfonic acid crystals are mixed with a plasticizer and heated to a molten state to obtain a mixed liquid M; ammonium trifluoromethanesulfonate and polyvinyl alcohol are prepared in proportion, and mixed to obtain a mixed liquid N; the mixed liquid M is extruded into particles with a particle size of 1-3 μm through an extruder, and the particles are placed in a cooling device at a temperature of 0°C for cooling and shaping.

[0059] 0059. Extrude the mixed liquid M into particles with a particle size of 1-3 μm through an extruder, place the particles in a cooling device at a temperature of -5°C to cool and shape, and finally spray the mixed liquid N on the surface of the above particles, stir evenly, and place them in a room temperature dryer to dry for later use. Modes for Carrying Out the Invention

[0060] The present invention will be further described in detail below in conjunction with specific implementation methods to better demonstrate the advantages of the present invention.

[0061] Example 1: A method for improving the adhesive properties of HMMM resin by methylal, comprising the following steps:

[0062] S1. Raw material preparation

[0063] Prepare 10.92 mol of methanol, 2.03 mol of a catalyst promoter, and 0.627 mol of hexamethylolmelamine; the catalyst promoter consists of a catalyst promoter A and a catalyst promoter B; wherein the catalyst promoter A comprises, by mass percentage, 7% ammonium trifluoromethanesulfonate, 2% hydrogenated rosin toluene, and the remainder of a mixed solution; the mixed solution is prepared from a methylal solution and anhydrous ethanol in a volume ratio of 1:1.5; the catalyst promoter B consists of a catalyst promoter A and a magnetic cobalt oxide accounting for 4.3% of the mass ratio of the catalyst promoter A;

[0064] In step S1, the preparation method of the catalyst promoter A is:

[0065] 1) Add hydrogenated rosin toluene and ammonium trifluoromethanesulfonate to a stirred tank and disperse in a vacuum at 100°C for 2.3 hours to obtain a premix, which is then set aside.

[0066] 2) Purifying the methylal solution for 2.5 hours to a purity of 99.5%, then mixing the methylal solution and anhydrous ethanol in proportion to obtain a mixed solution for later use;

[0067] 3) The mixed solution obtained in step 2) was first added to a reactor, and the premix obtained in step 1) was atomized using an atomizer to a particle size of 2.5 μm. The premix was then introduced into the reactor at a rate of 40 mL / min at 58° C. for 55 minutes. The temperature was raised to 78° C. and then continued to be introduced for 35 minutes. During the introduction, the mixture was stirred at a rate of 135 rpm. Finally, the temperature was lowered to 23° C. to obtain catalytic promoter A.

[0068] S2. Preparation of HMMM resin

[0069] S2-1, methanol, catalyst promoter and hexamethylolmelamine were added sequentially into a 1000 mL reactor equipped with a stirrer and a reflux condenser;

[0070] The steps for adding methanol, catalyst promoter and hexamethylolmelamine are as follows:

[0071] S2-1-1. Add 2 / 4 of methanol and hexamethylolmelamine to the reactor, and add catalytic aid A accounting for 5.3% of the mass of hexamethylolmelamine;

[0072] S2-1-2. Raise the temperature of the reactor to 37°C, continue to add 1 / 4 of the methanol and the remaining amount of catalyst promoter A, keep warm for 28 minutes and stir to mix, then raise the temperature to 60-70°C, add the remaining amount of methanol and the entire amount of catalyst promoter B, keep warm for 43 minutes and stir to mix;

[0073] S2-2, the reactor was heated to 50 ° C. After the material in the reactor became transparent, the temperature was kept warm and stirring was continued for 45 minutes, then alkali solution was added to adjust the pH to 8.5, and the remaining methylal, methanol and water were evaporated by heating. When the temperature reached 90 ° C., the vacuum system was started and the temperature was continued to be raised. When it reached 110 ° C., stirring was continued and the temperature was kept warm for 30 minutes, and then cooled to 90 ° C. and filtered, and distilled under reduced pressure to obtain HMMM resin;

[0074] In step 2), the purification method is as follows: according to the mass ratio of methylal solution: impurity remover of 8:30, the mixture is stirred at 58° C. for 30 minutes, and then allowed to stand for 1.3 hours. The upper layer of the standing liquid is subjected to ultrasonic adsorption treatment using an adsorbent at an ultrasonic frequency of 37 kHz and an ultrasonic power of 750 W. The standing liquid is then cooled to 22° C., the upper impurities are further separated and removed, and the bottom mixed liquid is distilled at room temperature and pressure using a distillation tower to obtain a purified methylal solution; the ultrasonic adsorption time is 18 minutes; the operating pressure of the distillation tower is 105 kPa; the adsorbent is activated carbon; and the impurity remover comprises, by mass percentage, 23% oxalic acid, 7% composite gel, and the remainder ammonium oxalate;

[0075] The composite gel is a modified composite gel obtained after modification treatment; the preparation method of the modified composite gel is:

[0076] The pH value was adjusted to 2.5 using 10% hydrochloric acid, and sodium methyl silicate and hydrogel were mixed in a reactor at a molar ratio of 1:2.2 and subjected to polymerization reaction to obtain a precursor solution; ethanol and deionized water were prepared in sequence according to a mass ratio of precursor solution: ethanol: deionized water of 3.5:6:6 and added to the reactor, heated to 87°C, kept warm and stirred for 30 minutes, and then aged at 23°C for 2.5 days; finally, the obtained mixed solution was vacuum dried to obtain a modified composite gel; wherein the drying temperature was 55°C and the drying time was 1.5 hours.

[0077] Example 2: The difference from Example 1 is that in step S1, 9.36 mol of methanol, 0.408 mol of catalyst promoter and 0.408 mol of hexahydroxymethylmelamine are prepared.

[0078] Example 3: The difference from Example 1 is that in step S1, 12.48 mol of methanol, 4.08 mol of catalyst promoter and 0.816 mol of hexahydroxymethylmelamine are prepared.

[0079] Example 4: Different from Example 1, in step S1, the catalyst aid A includes 5% ammonium trifluoromethanesulfonate, 1% hydrogenated rosin toluene and the remainder mixed solution in terms of mass percentage; the mixed solution is prepared by methylal solution: anhydrous ethanol in a volume ratio of 1:1.

[0080] Example 5: Different from Example 1, in step S1, the catalyst aid A includes 10% ammonium trifluoromethanesulfonate, 3% hydrogenated rosin toluene and the remainder mixed solution in terms of mass percentage; the mixed solution is prepared by methylal solution: anhydrous ethanol in a volume ratio of 1:2.

[0081] Example 6: Different from Example 1, in step S1, the preparation method of the catalyst aid A is:

[0082] 1) Add hydrogenated rosin toluene and ammonium trifluoromethanesulfonate to a stirred tank and disperse in a vacuum at 95°C for 2.5 hours to obtain a premix, which is then set aside.

[0083] 2) Purifying the methylal solution for 2 hours to a purity of 99.1%, then mixing the methylal solution and anhydrous ethanol in proportion to obtain a mixed solution for later use;

[0084] 3) The mixed solution obtained in step 2) was first added to a reactor, and the premix obtained in step 1) was atomized using an atomizer to a particle size of 2-3 μm. The premix was then introduced into the reactor at a rate of 50 mL / min at 55°C for 50 minutes. The temperature was raised to 75°C and then continued to be introduced for 40 minutes. During the introduction process, the mixture was stirred at a rate of 120 r / min. Finally, the temperature was lowered to 20°C to obtain catalytic aid A.

[0085] Example 7: Different from Example 1, in step S1, the preparation method of the catalyst aid A is:

[0086] 1) Add hydrogenated rosin toluene and ammonium trifluoromethanesulfonate to a stirred tank and disperse in a vacuum at 95°C for 2.5 hours to obtain a premix, which is then set aside.

[0087] 2) Purifying the methylal solution for 2 hours to a purity of 99.9%, then mixing the methylal solution and anhydrous ethanol in proportion to obtain a mixed solution for later use;

[0088] 3) The mixed solution obtained in step 2) was first added to a reactor, and the premix obtained in step 1) was atomized using an atomizer to a particle size of 2-3 μm. The premix was then introduced into the reactor at a rate of 50 mL / min at 60°C for 60 minutes. The temperature was raised to 80°C and then continued to be introduced for 30 minutes. During the introduction process, the mixture was stirred at a rate of 150 r / min. Finally, the temperature was lowered to 25°C to obtain catalytic aid A.

[0089] Example 8: The difference from Example 1 is that in step 2), the purification method is as follows: according to the mass ratio of methylal solution: impurity remover of 7:25, the mixture is stirred at 55°C for 35 minutes, and then allowed to stand for 1 hour. The upper layer of the standing liquid is ultrasonically adsorbed by an adsorbent at an ultrasonic frequency of 35kHz and an ultrasonic power of 700W, and then the standing liquid is cooled to 20°C, the upper impurities are further separated and removed, and the bottom mixed liquid is distilled at room temperature and pressure using a distillation tower to obtain a purified methylal solution; the ultrasonic adsorption time is 15 minutes; and the operating pressure of the distillation tower is 100kPa.

[0090] Example 9: The difference from Example 1 is that in step 2), the purification method is as follows: according to the mass ratio of methylal solution: impurity remover of 10:35, the mixture is stirred at 60°C for 25 minutes, and then allowed to stand for 1.5 hours. The upper layer of the standing liquid is ultrasonically adsorbed by an adsorbent at an ultrasonic frequency of 40kHz and an ultrasonic power of 800W, and then the standing liquid is cooled to 25°C, the upper impurities are further separated and removed, and the bottom mixed liquid is distilled at room temperature and pressure using a distillation tower to obtain a purified methylal solution; the ultrasonic adsorption time is 20 minutes; and the operating pressure of the distillation tower is 110kPa.

[0091] Example 10: Different from Example 1, in step 2), the impurity remover comprises, by mass percentage, 20% oxalic acid, 5% composite gel and the balance ammonium oxalate.

[0092] Example 11: Different from Example 1, in step 2), the impurity remover comprises, by mass percentage, 25% oxalic acid, 10% composite gel and the balance ammonium oxalate.

[0093] Example 12: Different from Example 1, in step S2-1, the steps of adding methanol, catalyst promoter and hexahydroxymethylmelamine are as follows:

[0094] S2-1-1. Add 1 / 4 of methanol and hexamethylolmelamine to the reactor, and add catalytic aid A accounting for 5% of the mass of hexamethylolmelamine;

[0095] S2-1-2. Raise the temperature of the reactor to 35°C, continue to add 2 / 4 of the methanol and the remaining amount of catalyst promoter A, keep warm for 25 minutes and stir to mix, then raise the temperature to 60°C, add the remaining amount of methanol and the entire amount of catalyst promoter B, keep warm for 50 minutes and stir to mix.

[0096] Example 13: Different from Example 1, in step S2-1, the steps of adding methanol, catalyst promoter and hexamethylolmelamine are as follows:

[0097] S2-1-1. Add 2 / 4 of methanol and hexamethylolmelamine to the reactor, and add catalytic aid A accounting for 5.5% of the mass of hexamethylolmelamine;

[0098] S2-1-2. Raise the temperature of the reactor to 40°C, continue to add 1 / 4 of the methanol and the remaining amount of catalyst promoter A, keep warm for 30 minutes and stir to mix, then raise the temperature to 70°C, add the remaining amount of methanol and the entire amount of catalyst promoter B, keep warm for 35 minutes and stir to mix.

[0099] Example 14: The difference from Example 1 is that in step S2-2, the reactor is heated to 45°C, and after the material in the reactor becomes transparent, it is kept warm and stirred for 50 minutes. Then, alkali solution is added to adjust the pH to 8, and the temperature is increased to remove the remaining methylal, methanol and water. When the temperature reaches 85°C, the vacuum system is started and the temperature is continued to be increased. When it reaches 105°C, stirring and keeping warm are continued for 35 minutes. Then, it is cooled to 85°C and filtered, and distilled under reduced pressure to obtain HMMM resin.

[0100] Example 15: Different from Example 1, in step S2-2, the reactor is heated to 55°C, and after the material in the reactor becomes transparent, it is kept warm and stirred for 40 minutes. Then, alkali solution is added to adjust the pH to 9, and the temperature is increased to evaporate the remaining methylal, methanol and water. When the temperature reaches 95°C, the vacuum system is started and the temperature is continued to be increased. When the temperature reaches 115°C, stirring and keeping warm are continued for 25 minutes. Then, it is cooled to 95°C and filtered, and distilled under reduced pressure to obtain HMMM resin.

[0101] Example 16: Different from Example 1, the preparation method of the modified composite gel is:

[0102] The pH value was adjusted to 2 using 10% hydrochloric acid, and sodium methyl silicate and hydrogel were mixed in a reactor at a molar ratio of 1:1.5 and subjected to polymerization reaction to obtain a precursor solution; ethanol and deionized water were prepared in sequence according to a mass ratio of precursor solution: ethanol: deionized water of 2.5:5:5 and added to the reactor, heated to 85°C, kept warm and stirred for 35 minutes, and then aged at 20°C for 3 days; finally, the obtained mixed solution was vacuum dried to obtain a modified composite gel; wherein the drying temperature was 50°C and the drying time was 2 hours.

[0103] Example 17: Different from Example 1, the preparation method of the modified composite gel is:

[0104] The pH value was adjusted to 3 using 10% hydrochloric acid, and sodium methyl silicate and hydrogel were mixed in a reactor at a molar ratio of 1:3 and subjected to polymerization reaction to obtain a precursor solution; ethanol and deionized water were prepared in sequence according to a mass ratio of precursor solution: ethanol: deionized water of 4.5:7:7 and added to the reactor, heated to 90°C, kept warm and stirred for 25 minutes, and then aged at 25°C for 2 days; finally, the obtained mixed solution was vacuum dried to obtain a modified composite gel; wherein the drying temperature was 60°C and the drying time was 1 hour.

[0105] Example 18: The difference from Example 1 is that ammonium trifluoromethanesulfonate is modified to obtain modified ammonium trifluoromethanesulfonate;

[0106] The modified ammonium trifluoromethanesulfonate is prepared by mixing benzenesulfonic acid crystals, plasticizer, ammonium trifluoromethanesulfonate and polyvinyl alcohol in a mass ratio of 1:0.4:2:3.

[0107] The preparation method of modified ammonium trifluoromethanesulfonate comprises: first drying benzenesulfonic acid crystals in an oven at a temperature of 40°C, then mixing the dried benzenesulfonic acid crystals with a plasticizer and heating them to a molten state to obtain a mixed solution M; preparing ammonium trifluoromethanesulfonate and polyvinyl alcohol in a certain proportion and mixing them to obtain a mixed solution N;

[0108] The mixed liquid M is extruded into particles with a particle size of 1-3 μm through an extruder, and the particles are placed in a cooling device at a temperature of -5°C to cool and shape. Finally, the mixed liquid N is sprayed on the surface of the above particles, stirred evenly, and placed in a room temperature dryer to dry for use.

[0109] Example 19: Different from Example 18, the modified ammonium trifluoromethanesulfonate is prepared by mixing benzenesulfonic acid crystals: plasticizer: ammonium trifluoromethanesulfonate: polyvinyl alcohol in a mass ratio of 1.1:0.5:2.5:4;

[0110] The preparation method of modified ammonium trifluoromethanesulfonate is as follows: first, benzenesulfonic acid crystals are placed in an oven at a temperature of 43°C for drying, a mixed liquid M is extruded into particles with a particle size of 1-3 μm through an extruder, and the particles are placed in a cooling device at a temperature of 0°C for cooling and shaping.

[0111] Example 20: Different from Example 18, the modified ammonium trifluoromethanesulfonate is prepared by mixing benzenesulfonic acid crystals: plasticizer: ammonium trifluoromethanesulfonate: polyvinyl alcohol in a mass ratio of 1.2:0.6:3:5;

[0112] The preparation method of ammonium trifluoromethanesulfonate is as follows: first, benzenesulfonic acid crystals are placed in an oven at a temperature of 45° C. for drying; a mixed liquid M is extruded into particles with a particle size of 1-3 μm by an extruder; and the particles are placed in a cooling device at a temperature of 5° C. for cooling and setting.

[0113] Experimental Example: For the HMMM resin prepared in each embodiment, 5 samples of each embodiment were taken. The viscosity and etherification degree test results of the 5 samples of each embodiment were averaged as the performance measurement results of the embodiment. The specific research is as follows:

[0114] 1. Investigate the effect of catalyst composition and proportion on the bonding performance of HMMM resin

[0115] Table 1 Properties of HMMM resins prepared in Examples 1-11, 16-18 and Comparative Examples 1-2

[0116]

[0117] Comparative Example 1: Different from Example 1, the premix is ​​not atomized in step 3).

[0118] Comparative Example 2: Different from Example 1, in step 2), the purification method is to directly use an impurity remover to remove impurities from the methylal solution.

[0119] Conclusion: It can be seen from the data of Examples 1-3 in Table 1 that the content of the catalyst promoter has little effect on the bonding properties of the prepared HMMM resin. It can be seen from the data of Examples 1 and 4-5 that with the increase in the proportion of ammonium trifluoromethanesulfonate and hydrogenated rosin toluene, the performance of the HMMM resin shows a trend of first increasing and then decreasing, and reaches the best at the ratio of Example 1. It can be seen that in the synthesis process of methylal, an appropriate amount of ammonium trifluoromethanesulfonate can catalyze the formation of methylal and improve the yield and purity of the product, but an excessive amount will have an adverse effect; hydrogenated rosin toluene can improve the water absorption properties of methylal. When hydrogenated rosin toluene is excessive, it will form more microstructures in methylal, increase the water absorption capacity and water absorption rate of methylal, but excessive hydrogenated rosin toluene may affect the stability of methylal, thereby reducing the promoting effect of methylal on the etherification reaction;

[0120] From the data comparison of Example 1, Examples 6-7 and Control Example 1, it can be seen that the catalyst promoter A prepared without atomization treatment in the control example has a smaller promoting effect on the bonding performance of HMMM resin. This is because the hydrogenated rosin toluene and ammonium trifluoromethanesulfonate are first dispersed under vacuum and then atomized, which can effectively promote the uniform dispersion of the premix and improve its quality and stability. The atomization treatment can increase the surface area of ​​the material, improve the reaction rate and adsorption performance, and is also conducive to the uniform dispersion and stability of the material.

[0121] From the data comparison of Examples 1, 8-11, 16-18 and Control Example 2, it can be seen that although the direct treatment of the methylal solution with an impurity remover in Control Example 2 can play a certain impurity removal role, the effect is limited; while in Examples 16-18, the composite gel in the impurity remover component is modified so that the composite gel has the ability to absorb water while having the impurity removal effect, thereby further improving the bonding performance of the HMMM resin. Taking all factors into consideration, the HMMM resin prepared in Example 17 has the best bonding performance.

[0122] Investigate the effect of the preparation process of HMMM resin on the bonding properties of HMMM resin

[0123] Table 2 Properties of HMMM resins prepared in Examples 1, 12-15 and Comparative Example 3

[0124]

[0125] Comparative Example 3: Different from Example 1, in step S2-1, the catalyst promoter A and the catalyst promoter B are directly stirred and mixed with methanol and hexamethylolmelamine.

[0126] Conclusion: From the data comparison of Example 1, Examples 12-13 and Control Example 4 in Table 2, it can be seen that adding catalytic promoter A and catalytic promoter B to the reactor step by step further enhances the effect of catalytic promoter B, so that the magnetic cobalt oxide is better dispersed in methylal, further improves the etherification effect, and thus improves the effect of methylal on the viscosity of HMMM resin; and from the data comparison of Example 1 and Examples 14-15, it can be seen that the parameters for preparing HMMM resin within the range of right 1 have little effect on the bonding of HMMM resin.

[0127] Investigating the effect of ammonium trifluoromethanesulfonate modification on the bonding properties of HMMM resin

[0128] Table 3 Properties of HMMM resins prepared in Example 17 and Examples 18-20

[0129]

[0130] Conclusion: From the data comparison of Examples 17-20 in Table 3, it can be seen that the bonding performance of the HMMM resin prepared in Examples 18-20 is significantly improved compared with Example 17, and the bonding performance of the HMMM resin prepared by Example 19 is the best; this is because by plasticizing the benzenesulfonic acid crystals and then spraying ammonium trifluoromethanesulfonate on the surface of the benzenesulfonic acid particles, the specific surface area of ​​the modified ammonium trifluoromethanesulfonate can be effectively increased, and the promoting effect of the modified ammonium trifluoromethanesulfonate in promoting the etherification of methylal can be further enhanced. In addition, the use of benzenesulfonic acid crystals as a carrier can provide a strongly acidic environment, which helps to improve the activity of polyvinyl alcohol, thereby promoting the diffusion of ammonium trifluoromethanesulfonate and significantly improving the bonding performance of the HMMM resin.

Claims

1. A method for improving the adhesive properties of HMMM resin by using methylal, characterized in that: The following steps are involved: S1. Raw material preparation Prepare 9.36-12.48 mol of methanol, 0.408-4.08 mol of a catalyst promoter, and 0.408-0.816 mol of hexamethylolmelamine; the catalyst promoter is composed of a catalyst promoter A and a catalyst promoter B; wherein the catalyst promoter A comprises, by mass percentage, 5-10% ammonium trifluoromethanesulfonate, 1-3% hydrogenated rosin toluene, and the remainder a mixed solution; the mixed solution is prepared from a methylal solution and anhydrous ethanol in a volume ratio of 1:1-2; the catalyst promoter B is composed of a catalyst promoter A and 3.5-5% by mass of magnetic cobalt oxide of the catalyst promoter A; S2. Preparation of HMMM resin S2-1, methanol, catalyst promoter and hexamethylolmelamine were added sequentially into a 1000 mL reactor equipped with a stirrer and a reflux condenser; S2-2. Heat the reactor to 45-55°C. After the material in the reactor becomes transparent, keep it warm and continue stirring for 40-50 minutes. Then add alkali solution to adjust the pH to 8-9. Heat and evaporate the remaining methylal, methanol and water. When the temperature reaches 85-95°C, start the vacuum system and continue to heat. When the temperature reaches 105-115°C, continue stirring and keeping warm for 25-35 minutes. Then cool to 85-95°C and filter. Distill under reduced pressure to obtain HMMM resin.

2. The method for improving the bonding performance of HMMM resin by using methylal according to claim 1, wherein: In step S2-1, the steps of adding methanol, catalyst promoter and hexamethylolmelamine are as follows: S2-1-1. Add 1 / 4-3 / 4 of methanol and hexamethylolmelamine to the reactor, and add catalytic aid A accounting for 5-5.5% of the mass of hexamethylolmelamine; S2-1-2. Raise the temperature of the reactor to 35-40°C, continue to add 1 / 4-3 / 4 of methanol and the remaining amount of catalyst promoter A, keep warm for 25-30 minutes and stir to mix, then raise the temperature to 60-70°C, add the remaining amount of methanol and the entire amount of catalyst promoter B, keep warm for 35-50 minutes and stir to mix.

3. The method for improving the bonding performance of HMMM resin by using methylal according to claim 1, wherein: In step S1, the preparation method of the catalyst aid A is: 1) Add hydrogenated rosin toluene and ammonium trifluoromethanesulfonate to a stirred tank and disperse under vacuum at 95-105°C for 2-2.5 hours to obtain a premix, which is then set aside. 2) Purifying the methylal solution for 2-3 hours to a purity of 99.1-99.9%, then mixing the methylal solution with anhydrous ethanol in proportion to obtain a mixed solution for later use; 3) The mixed solution obtained in step 2) is first added to a reactor, and the premix obtained in step 1) is atomized using an atomizer to a particle size of 2-3 μm. The premix is ​​then introduced into the reactor at a rate of 30-50 mL / min at a temperature of 55-60° C. for 50-60 minutes. The temperature is raised to 75-80° C. and then continued to be introduced for 30-40 minutes. During the introduction process, the mixture is stirred and mixed at a rate of 120-150 r / min. Finally, the temperature is lowered to 20-25° C. to obtain catalytic promoter A.

4. A method for improving the bonding performance of HMMM resin by using methylal according to claim 3, characterized in that: In step 2), the purification method is as follows: methylal solution: impurity remover are mixed in a mass ratio of 7-10:25-35 and stirred at 55-60°C for 25-35 minutes, then allowed to stand for 1-1.5 hours, and the upper layer of the standing liquid is ultrasonically adsorbed using an adsorbent at an ultrasonic frequency of 35-40kHz and an ultrasonic power of 700-800W. The standing liquid is then cooled to 20-25°C, the upper layer of impurities is further separated and removed, and the bottom mixed liquid is distilled at room temperature and pressure using a distillation tower to obtain a purified methylal solution; the ultrasonic adsorption time is 15-20 minutes; the operating pressure of the distillation tower is 100-110kPa; and the adsorbent is selected from either molecular sieves or activated carbon.

5. A method for improving the bonding performance of HMMM resin by using methylal according to claim 4, characterized in that: The impurity remover comprises, by weight percentage, 20-25% of oxalic acid, 5-10% of composite gel and the balance of ammonium oxalate.

6. A method for improving the adhesive properties of HMMM resin by using methylal according to claim 5, characterized in that: The composite gel is a modified composite gel obtained after modification treatment; the preparation method of the modified composite gel is: The pH value is adjusted to 2-3 using hydrochloric acid with a mass concentration of 10%, and sodium methyl silicate and hydrogel are mixed in a reactor at a molar ratio of 1:1.5-3 and subjected to a polymerization reaction to obtain a precursor solution; ethanol and deionized water are prepared in sequence according to a mass ratio of precursor solution: ethanol: deionized water of 2.5-4.5:5-7:5-7 and added to the reactor, heated to 85-90°C, stirred at this temperature for 25-35 minutes, and then aged at 20-25°C for 2-3 days; finally, the obtained mixed solution is vacuum dried to obtain a modified composite gel; wherein the drying temperature is 50-60°C and the drying time is 1-2 hours.

7. The method for improving the bonding performance of HMMM resin by using methylal according to claim 1, characterized in that: Modifying the ammonium trifluoromethanesulfonate to obtain modified ammonium trifluoromethanesulfonate; The modified ammonium trifluoromethanesulfonate is prepared by mixing benzenesulfonic acid crystals: plasticizer: ammonium trifluoromethanesulfonate: polyvinyl alcohol in a mass ratio of 1-1.2:0.4-0.6:2-3:0.5-0.7; The modified ammonium trifluoromethanesulfonate preparation method comprises: first drying benzenesulfonic acid crystals in an oven at a temperature of 40-45° C., then mixing the dried benzenesulfonic acid crystals with a plasticizer and heating them to a molten state to obtain a mixed liquid M; preparing ammonium trifluoromethanesulfonate and polyvinyl alcohol in a certain proportion, and mixing them to obtain a mixed liquid N; The mixed liquid M is extruded into particles with a particle size of 1-3 μm through an extruder, and the particles are placed in a cooling device at a temperature of -5 to 5°C to cool and shape them. Finally, the mixed liquid N is sprayed on the surface of the above particles, stirred evenly, and placed in a room temperature dryer to dry for use.

8. The method for improving the adhesive properties of HMMM resin by using methylal according to claim 7, wherein: The plasticizer is any one of epoxy vegetable oil, trimethoxysilane and polyethylene glycol.

9. The method for improving the adhesive properties of HMMM resin by using methylal according to claim 1, wherein: The alkali solution is any one of a sodium hydroxide solution with a mass fraction of 10-15% and a potassium hydroxide solution with a mass fraction of 10-15%.