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

Abstract

The invention discloses a method for improving the bonding performance of HMMM resin by using methylal, comprising the following steps: S1, raw material preparation: preparing 9.36-12.48 mol of methanol, 0.408-4.08 mol of a catalyst aid and 0.408-0.816 mol of hexamethylol melamine; S2, preparing the HMMM resin: S2-1, sequentially adding methanol, the catalyst aid and the hexamethylol melamine into a 1000 mL reactor with a stirrer and a reflux condenser, heating up under alkaline conditions to evaporate the remaining methylal, methanol and water, and performing reduced pressure distillation to obtain the HMMM resin; the method promotes the reaction of methylal with water to generate hexamethoxymethyl melamine by the composite action of the catalyst aid A and the catalyst aid B, thereby improving the water absorption effect of the methylal solution; at the same time, the magnetic cobalt oxide can be fully mixed with the methanol during the magnetic cation exchange resin, further accelerating the etherification reaction, improving the etherification effect, thereby effectively improving the bonding performance of the HMMM resin.

Description

Technical Field

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

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

[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. In the etherification reaction of methanol and hexahydroxymethyl melamine to prepare HMMM resin, methylal is added at the same time (methylal is a compound generated by 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 to the formation of etherification products, and the reduction of water can also reduce the condensation polymerization between molecules. The above method for preparing HMMM resin can improve the bonding properties of HMMM resin to a certain extent, but the improvement effect is limited. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a method for improving the bonding performance of HMMM resin by using methylal.

[0005] The technical solution of the present invention is: a method for improving the bonding performance of HMMM resin by methylal, comprising the following steps:

[0006] S1. Raw material preparation

[0007] Prepare 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; the catalyst promoter includes a catalyst promoter A and a catalyst promoter B; wherein the catalyst promoter A includes 5-10% of ammonium trifluoromethanesulfonate, 1-3% of hydrogenated rosin toluene and the remainder of a mixed solution in terms of mass percentage; the mixed solution is prepared from methylal solution: anhydrous ethanol in a volume ratio of 1:1-2; the catalyst promoter B is composed of the catalyst promoter A and magnetic cobalt oxide accounting for 3.5-5% of the mass ratio of the catalyst promoter A;

[0008] S2. Preparation of HMMM resin

[0009] S2-1, adding methanol, catalyst promoter and hexamethylolmelamine in sequence into a 1000 mL reaction kettle equipped with a stirrer and a reflux condenser;

[0010] S2-2, heating the reactor to 45-55°C, keeping the temperature and stirring for 40-50min after the material in the reactor becomes transparent, then adding alkali solution to adjust the pH to 8-9, heating to evaporate the remaining methylal, methanol and water, and starting the vacuum system and continuing to heat when the temperature reaches 85-95°C, stirring and keeping the temperature for 25-35min when the temperature reaches 105-115°C, then cooling to 85-95°C and filtering, and distilling under reduced pressure to obtain HMMM resin;

[0011] Description: Ammonium trifluoromethanesulfonate can effectively promote the reaction of methylal and water to generate 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 generate 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, improving the etherification effect and thus improving the viscosity of the HMMM resin.

[0012] Furthermore, in step S2-1, the step of adding methanol, catalyst promoter and hexahydroxymethylmelamine is:

[0013] S2-1-1, adding 1 / 4-3 / 4 of methanol and hexamethylolmelamine to a reaction kettle, and adding a catalyst aid A accounting for 5-5.5% of the mass of hexamethylolmelamine;

[0014] 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;

[0015] 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 the viscosity of HMMM resin.

[0016] Furthermore, in step S1, the preparation method of the catalyst promoter A is:

[0017] 1) Add hydrogenated rosin toluene and ammonium trifluoromethanesulfonate into a stirring kettle, and disperse them under vacuum at 95-105° C. for 2-2.5 hours to obtain a premix for standby use;

[0018] 2) purifying the methylal solution for 2-3 hours until the purity is 99.1-99.9%, then mixing the methylal solution and anhydrous ethanol according to a proportion to obtain a mixed solution for standby use;

[0019] 3) The mixed solution obtained in step 2) is first added to a reactor, and the premix obtained in step 1) is treated with an atomizer to a particle size of 2-3 μm, and then the premix is ​​introduced into the reactor at a rate of 30-50 mL / min at a temperature of 55-60° C. for 50-60 min, and the temperature is raised to 75-80° C., and then the premix is ​​continued to be introduced for 30-40 min. During the introduction process, the mixture is stirred and mixed at a speed of 120-150 r / min, and finally the temperature is lowered to 20-25° C. to obtain a catalytic promoter A.

[0020] Description: Dispersing hydrogenated rosin toluene and ammonium trifluoromethanesulfonate under vacuum and then atomizing can effectively promote the uniform dispersion of the premix and improve its quality and stability. Atomizing 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.

[0021] Further, in step 2), the purification method is: according to the mass ratio of methylal solution: impurity remover of 7-10:25-35, the mixture is stirred at 55-60°C for 25-35min, and then allowed to stand for 1-1.5h, and the upper layer of the standing liquid is subjected to ultrasonic adsorption treatment using an adsorbent under the conditions of an ultrasonic frequency of 35-40kHz and an ultrasonic power of 700-800W, and then the standing liquid is cooled to 20-25°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 15-20min; the operating pressure of the distillation tower is 100-110kPa; the adsorbent is selected from any one of molecular sieves and activated carbon;

[0022] 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.

[0023] Furthermore, the impurity remover comprises, by mass percentage, 20-25% of oxalic acid, 5-10% of composite gel and the balance of ammonium oxalate;

[0024] Description: The impurity remover with the above ingredients can effectively remove impurities in the methylal solution while having little effect on the performance of the methylal.

[0025] Furthermore, the composite gel is a modified composite gel obtained after modification; the preparation method of the modified composite gel is:

[0026] 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 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 1-2h;

[0027] Description: Hydrogel is an extremely hydrophilic three-dimensional network structure gel, which swells rapidly in water and can retain a large volume of water without dissolving in this swollen state, so it has strong water absorption performance. Polymerizing silicate molecules with hydrogel to generate copolymers containing both silicate and hydrogel segments can make the composite gel have water absorption performance while having impurity removal effect, thereby further improving the water absorption effect and achieving the purpose of improving the bonding performance of HMMM resin.

[0028] Further, the ammonium trifluoromethanesulfonate is modified to obtain modified ammonium trifluoromethanesulfonate;

[0029] 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;

[0030] The preparation method of the modified ammonium trifluoromethanesulfonate is as follows: firstly, benzenesulfonic acid crystals are placed in an oven at a temperature of 40-45° 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; the ammonium trifluoromethanesulfonate and polyvinyl alcohol are prepared in proportion and mixed to obtain a mixed liquid N;

[0031] 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 for cooling and shaping, and finally the mixed liquid N is sprayed on the surface of the particles, stirred evenly, and placed in a normal temperature dryer for drying for later use;

[0032] Description: The above method can effectively increase the specific surface area of ​​modified ammonium trifluoromethanesulfonate by first plasticizing benzenesulfonic acid crystals and then spraying ammonium trifluoromethanesulfonate on the surface of benzenesulfonic acid particles, further enhancing the promoting effect of modified ammonium trifluoromethanesulfonate in the process of etherification of methylal, thereby enhancing the absorption capacity of water generated in the etherification reaction, reducing the free water generated in the etherification reaction system, and significantly improving the performance of HMMM resin.

[0033] Furthermore, the plasticizer is any one of epoxy vegetable oil, trimethoxysilane, and polyethylene glycol;

[0034] Note: The above plasticizer can promote the melting of benzenesulfonic acid crystals, thereby improving the preparation efficiency of particles.

[0035] Furthermore, 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%;

[0036] Note: The above-mentioned alkali solution will not produce harmful substances during use and will not pollute the environment; it can efficiently change the pH value and further improve the treatment effect.

[0037] The beneficial effects of the present invention are:

[0038] (1) The present invention promotes the reaction of methylal with water to generate hexamethoxymethyl melamine through the catalyst 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 improving the etherification effect, thereby effectively improving the bonding performance of the HMMM resin.

[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 utilizes the three-dimensional network structure of the hydrogel to rapidly swell in water and have strong water absorption performance in this swollen state, thereby further enhancing the promoting effect on the etherification reaction, thereby improving the bonding performance of the HMMM resin.

[0040] (3) The present invention can effectively increase the specific surface area of ​​modified ammonium trifluoromethanesulfonate by plasticizing benzenesulfonic acid crystals and then spraying ammonium trifluoromethanesulfonate on the surface of benzenesulfonic acid particles, further enhancing the promoting effect of modified ammonium trifluoromethanesulfonate in the process of etherification of methylal, and using benzenesulfonic acid crystals as a carrier can provide a strong 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 HMMM resin. DETAILED DESCRIPTION

[0041] The present invention is further described in detail below in conjunction with specific implementation methods to better reflect the advantages of the present invention.

[0042] Example 1: A method for improving the bonding performance of HMMM resin by methylal, comprising the following steps:

[0043] S1. Raw material preparation

[0044] Prepare 10.92 mol of methanol, 2.03 mol of catalyst promoter and 0.627 mol of hexamethylol melamine; the catalyst promoter is composed of catalyst promoter A and catalyst promoter B; wherein the catalyst promoter A comprises 7% of ammonium trifluoromethanesulfonate, 2% of hydrogenated rosin toluene and the remainder of a mixed solution by mass percentage; the mixed solution is prepared from methylal solution: anhydrous ethanol in a volume ratio of 1:1.5; the catalyst promoter B is composed of catalyst promoter A and magnetic cobalt oxide accounting for 4.3% of the mass ratio of the catalyst promoter A;

[0045] In step S1, the preparation method of the catalyst promoter A is:

[0046] 1) Add hydrogenated rosin toluene and ammonium trifluoromethanesulfonate into a stirring kettle, and disperse them under vacuum at 100° C. for 2.3 h to obtain a premix for standby use;

[0047] 2) purifying the methylal solution for 2.5 hours until the purity is 99.5%, then mixing the methylal solution and anhydrous ethanol according to a proportion to obtain a mixed solution for standby use;

[0048] 3) adding the mixed solution obtained in step 2) into a reactor, and using an atomizer to atomize the premix obtained in step 1) to a particle size of 2.5 μm, and then introducing the premix into the reactor at a rate of 40 mL / min at a temperature of 58° C. for 55 min, raising the temperature to 78° C., and then continuing to introduce the premix for 35 min. During the introduction process, stirring and mixing at a speed of 135 r / min, and finally cooling to 23° C., a catalyst promoter A is obtained;

[0049] S2. Preparation of HMMM resin

[0050] S2-1, adding methanol, catalyst promoter and hexamethylolmelamine in sequence into a 1000 mL reaction kettle equipped with a stirrer and a reflux condenser;

[0051] The steps of adding methanol, catalyst promoter and hexamethylolmelamine are as follows:

[0052] S2-1-1, adding 2 / 4 of methanol and hexahydroxymethyl melamine to a reaction kettle, and adding a catalyst aid A accounting for 5.3% of the mass of hexahydroxymethyl melamine;

[0053] 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 the 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 the catalyst promoter B, keep warm for 43 minutes and stir to mix;

[0054] S2-2, the reactor was heated to 50 ° C, and the materials in the reactor were kept warm and stirred for 45 minutes after they became transparent, and 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 the temperature reached 110 ° C, stirring and heat preservation were continued for 30 minutes, and then cooled to 90 ° C and filtered, and distilled under reduced pressure to obtain HMMM resin;

[0055] 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 30min, and then allowed to stand for 1.3h, and the upper layer of the standing liquid is subjected to ultrasonic adsorption treatment by an adsorbent under the conditions of an ultrasonic frequency of 37kHz and an ultrasonic power of 750W, and then the standing liquid is cooled to 22°C, and the upper impurities are further separated and removed, and the bottom mixed liquid is distilled at room temperature and pressure by a distillation tower to obtain a purified methylal solution; the ultrasonic adsorption time is 18min; the operating pressure of the distillation tower is 105kPa; the adsorbent is activated carbon; the impurity remover includes 23% oxalic acid, 7% composite gel and the remainder ammonium oxalate according to mass percentage;

[0056] The composite gel is a modified composite gel obtained after modification; the preparation method of the modified composite gel is as follows:

[0057] The pH value was adjusted to 2.5 using hydrochloric acid with 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 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 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.

[0058] Example 2: Different from Example 1, in step S1, 9.36 mol of methanol, 0.408 mol of catalyst promoter and 0.408 mol of hexahydroxymethylmelamine are prepared.

[0059] Example 3: Different from Example 1, in step S1, 12.48 mol of methanol, 4.08 mol of catalyst promoter and 0.816 mol of hexahydroxymethylmelamine are prepared.

[0060] Example 4: Different from Example 1, in step S1, the catalyst promoter A includes 5% ammonium trifluoromethanesulfonate, 1% hydrogenated rosin toluene and the remainder mixed liquid in terms of mass percentage; the mixed liquid is prepared from methylal solution: anhydrous ethanol in a volume ratio of 1:1.

[0061] 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 liquid in terms of mass percentage; the mixed liquid is prepared from methylal solution: anhydrous ethanol in a volume ratio of 1:2.

[0062] Example 6: Different from Example 1, in step S1, the preparation method of the catalyst promoter A is:

[0063] 1) Add hydrogenated rosin toluene and ammonium trifluoromethanesulfonate into a stirring kettle, and disperse them under vacuum at 95° C. for 2.5 hours to obtain a premix for standby use;

[0064] 2) purifying the methylal solution for 2 hours until the purity is 99.1%, then mixing the methylal solution and anhydrous ethanol according to a proportion to obtain a mixed solution for standby use;

[0065] 3) The mixed solution obtained in step 2) is first added to the reactor, and the premix obtained in step 1) is atomized by an atomizer to a particle size of 2-3 μm, and then the premix is ​​introduced into the reactor at a rate of 50 mL / min at a temperature of 55° C. for 50 min, the temperature is raised to 75° C., and then the introduction is continued for 40 min. During the introduction process, the mixture is stirred and mixed at a speed of 120 r / min, and finally the temperature is lowered to 20° C. to obtain catalytic aid A.

[0066] Embodiment 7: Different from Embodiment 1, in step S1, the preparation method of the catalyst promoter A is:

[0067] 1) Add hydrogenated rosin toluene and ammonium trifluoromethanesulfonate into a stirring kettle, and disperse them under vacuum at 95° C. for 2.5 hours to obtain a premix for standby use;

[0068] 2) purifying the methylal solution for 2 hours until the purity is 99.9%, then mixing the methylal solution and anhydrous ethanol according to a proportion to obtain a mixed solution for standby use;

[0069] 3) The mixed solution obtained in step 2) is first added to the reactor, and the premix obtained in step 1) is atomized by an atomizer to a particle size of 2-3 μm, and then the premix is ​​introduced into the reactor at a rate of 50 mL / min at a temperature of 60° C. for 60 min, and the temperature is raised to 80° C., and then the introduction is continued for 30 min. During the introduction process, the mixture is stirred and mixed at a speed of 150 r / min, and finally the temperature is lowered to 25° C. to obtain catalytic aid A.

[0070] Embodiment 8: The difference from Embodiment 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 min, and then allowed to stand for 1 h. The upper layer of the standing liquid is subjected to ultrasonic adsorption by an adsorbent at an ultrasonic frequency of 35 kHz and an ultrasonic power of 700 W, 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 by a distillation tower to obtain a purified methylal solution; the ultrasonic adsorption time is 15 min; and the operating pressure of the distillation tower is 100 kPa.

[0071] Embodiment 9: The difference from Embodiment 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 min, and then allowed to stand for 1.5 h, and the upper layer of the standing liquid is ultrasonically adsorbed by an adsorbent at an ultrasonic frequency of 40 kHz and an ultrasonic power of 800 W, 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 by a distillation tower to obtain a purified methylal solution; the ultrasonic adsorption time is 20 min; and the operating pressure of the distillation tower is 110 kPa.

[0072] Example 10: Different from Example 1, in step 2), the impurity remover comprises, by mass percentage, 20% oxalic acid, 5% composite gel and the remainder ammonium oxalate.

[0073] Example 11: Different from Example 1, in step 2), the impurity remover comprises, by mass percentage, 25% oxalic acid, 10% composite gel and the remainder ammonium oxalate.

[0074] Example 12: Different from Example 1, in step S2-1, the steps of adding methanol, catalyst promoter and hexahydroxymethylmelamine are:

[0075] S2-1-1, adding 1 / 4 of methanol and hexamethylolmelamine to a reaction kettle, and adding a catalyst aid A accounting for 5% of the mass of hexamethylolmelamine;

[0076] 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 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 B, keep warm for 50 minutes and stir to mix.

[0077] Example 13: Different from Example 1, in step S2-1, the steps of adding methanol, catalyst promoter and hexahydroxymethylmelamine are as follows:

[0078] S2-1-1, adding 2 / 4 of methanol and hexamethylolmelamine to a reaction kettle, and adding a catalyst aid A accounting for 5.5% of the mass of hexamethylolmelamine;

[0079] 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 the catalyst 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 the catalyst B, keep warm for 35 minutes and stir to mix.

[0080] Example 14: Different from Example 1, 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, and then alkali solution is added to adjust the pH to 8, and the temperature is raised to evaporate the remaining methylal, methanol and water. When the temperature reaches 85°C, the vacuum system is started and the temperature is continued to be raised. When the temperature reaches 105°C, stirring and keeping warm are continued for 35 minutes, and then it is cooled to 85°C and filtered, and distilled under reduced pressure to obtain HMMM resin.

[0081] 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, and then alkali solution is added to adjust the pH to 9, and the temperature is raised 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 raised. When the temperature reaches 115°C, it is continued to be stirred and kept warm for 25 minutes, and then cooled to 95°C and filtered, and distilled under reduced pressure to obtain HMMM resin.

[0082] Example 16: Different from Example 1, the preparation method of the modified composite gel is:

[0083] 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 at a mass ratio of 2.5:5:5 of precursor solution: ethanol: deionized water 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 mixed solution obtained above was vacuum dried to obtain a modified composite gel; wherein the drying temperature was 50°C and the drying time was 2 hours.

[0084] Example 17: Different from Example 1, the preparation method of the modified composite gel is:

[0085] The pH value was adjusted to 3 using hydrochloric acid with a mass concentration of 10%, 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 mixed solution obtained above was vacuum dried to obtain a modified composite gel; wherein the drying temperature was 60°C and the drying time was 1 hour.

[0086] Embodiment 18: The difference from Embodiment 1 is that ammonium trifluoromethanesulfonate is modified to obtain modified ammonium trifluoromethanesulfonate;

[0087] The modified ammonium trifluoromethanesulfonate is prepared by mixing benzenesulfonic acid crystals: plasticizer: ammonium trifluoromethanesulfonate: polyvinyl alcohol in a mass ratio of 1:0.4:2:3;

[0088] The preparation method of modified ammonium trifluoromethanesulfonate is as follows: firstly, benzenesulfonic acid crystals are placed in an oven at a temperature of 40°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 according to a proportion, and mixed to obtain a mixed liquid N;

[0089] 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°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 normal temperature dryer to dry for use.

[0090] 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;

[0091] 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 by an extruder, and the particles are placed in a cooling device at a temperature of 0° C. for cooling and shaping.

[0092] 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;

[0093] 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 shaping.

[0094] Experimental Example: For the HMMM resin prepared in each embodiment, 5 samples of each embodiment were taken, and 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 exploration is as follows:

[0095] 1. Explore the influence of catalyst composition and proportion on the bonding performance of HMMM resin

[0096] Table 1 Performance of HMMM resins prepared in Examples 1-11, 16-18 and Comparative Examples 1-2

[0097]

[0098] Comparative Example 1: Different from Example 1, the premix is ​​not atomized in step 3).

[0099] 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.

[0100] Conclusion: From the data of Examples 1-3 in Table 1, it can be seen that the content of the catalyst promoter has little effect on the bonding performance of the prepared HMMM resin. From the data of Examples 1 and 4-5, it can be seen 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; and hydrogenated rosin toluene can improve the water absorption performance 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 an excessive amount of hydrogenated rosin toluene may affect the stability of methylal, thereby reducing the promoting effect of methylal on the etherification reaction;

[0101] 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.

[0102] From the data comparison of Example 1, Examples 8-11, Examples 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 Examples 16-18 modify the composite gel in the impurity remover component 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 bonding performance of the HMMM resin prepared in Example 17 reaches the best.

[0103] 2. Investigate the effect of the preparation process of HMMM resin on the bonding properties of HMMM resin

[0104] Table 2 Properties of HMMM resin prepared in Examples 1, 12-15 and Comparative Example 3

[0105]

[0106]

[0107] 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 hexahydroxymethylmelamine.

[0108] Conclusion: From the data comparison of Example 1, Examples 12-13 and Control Example 4 in Table 2, it can be obtained that adding catalytic aid A and catalytic aid B into the reactor step by step further enhances the effect of catalytic aid 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 obtained that the parameters for preparing HMMM resin within the range of right 1 have little effect on the bonding of HMMM resin.

[0109] 3. Investigate the effect of ammonium trifluoromethanesulfonate modification on the bonding properties of HMMM resin

[0110] Table 3 Performance of HMMM resin prepared in Example 17 and Examples 18-20

[0111]

[0112] Conclusion: From the data comparison of Examples 17-20 in Table 3, it can be obtained that the bonding performance of the HMMM resin prepared in Examples 18-20 is significantly improved compared with that in 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 modified ammonium trifluoromethanesulfonate can further enhance the promoting effect of methylal in the etherification process, and the use of benzenesulfonic acid crystals as a carrier can provide a strong 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 bonding performance of HMMM resin by 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 hexamethylol melamine; 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% 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: anhydrous ethanol in a volume ratio of 1:1-2; the catalyst promoter B is composed of a catalyst promoter A and magnetic cobalt oxide accounting for 3.5-5% of the mass ratio of the catalyst promoter A; In step S1, the preparation method of the catalyst promoter A is: 1) Add hydrogenated rosin toluene and ammonium trifluoromethanesulfonate into a stirring kettle, and disperse them under vacuum at 95-105° C. for 2-2.5 hours to obtain a premix for standby use; 2) purifying the methylal solution for 2-3 hours until the purity is 99.1-99.9%, then mixing the methylal solution and anhydrous ethanol according to a proportion to obtain a mixed solution for standby use; 3) adding the mixed solution obtained in step 2) into a reactor, and using an atomizer to atomize the premix obtained in step 1) to a particle size of 2-3 μm, and then introducing the premix into the reactor at a rate of 30-50 mL / min at a temperature of 55-60° C. for 50-60 min, heating to 75-80° C., and then continuing to introduce for 30-40 min. During the introduction, stirring and mixing at a speed of 120-150 r / min, and finally cooling to 20-25° C., a catalyst promoter A is obtained; In step 2), the purification method is as follows: according to the mass ratio of methylal solution to impurity remover of 7-10:25-35, the mixture is stirred at 55-60°C for 25-35min, and then allowed to stand for 1-1.5h, and the upper layer of the standing liquid is subjected to ultrasonic adsorption treatment using an adsorbent under the conditions of an ultrasonic frequency of 35-40kHz and an ultrasonic power of 700-800W, and then the standing liquid is cooled to 20-25°C, and 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 15-20min; the operating pressure of the distillation tower is 100-110kPa; the adsorbent is selected from any one of molecular sieves and activated carbon; S2. Preparation of HMMM resin S2-1, adding methanol, catalyst promoter and hexamethylolmelamine in sequence into a 1000 mL reaction kettle equipped with a stirrer and a reflux condenser; S2-2, heat the reactor to 45-55°C, keep warm and continue stirring for 40-50 minutes after the materials in the reactor are transparent, then add alkali solution to adjust the pH to 8-9, heat and evaporate the remaining methylal, methanol and water, start the vacuum system and continue to heat when the temperature reaches 85-95°C, continue to stir and keep warm for 25-35 minutes when the temperature reaches 105-115°C, then cool to 85-95°C and filter, and distill under reduced pressure to obtain HMMM resin.

2. A method for improving the bonding performance of HMMM resin by methylal according to claim 1, characterized in that: In step S2-1, the steps of adding methanol, catalyst promoter and hexahydroxymethylmelamine are: S2-1-1, adding 1 / 4-3 / 4 of methanol and hexamethylolmelamine to a reaction kettle, and adding a catalyst 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 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 B, keep warm for 35-50 minutes and stir to mix.

3. A method for improving the bonding performance of HMMM resin by methylal according to claim 1, characterized in that: The impurity remover comprises, by mass percentage, 20-25% of oxalic acid, 5-10% of composite gel and the balance of ammonium oxalate.

4. A method for improving the bonding performance of HMMM resin by methylal as claimed in claim 3, characterized in that: The composite gel is a modified composite gel obtained after modification; 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 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 1-2h.

5. A method for improving the bonding performance of HMMM resin by 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 preparation method of the modified ammonium trifluoromethanesulfonate is as follows: firstly, benzenesulfonic acid crystals are placed in an oven at a temperature of 40-45° 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; the 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 by an extruder, and the particles are placed in a cooling device at a temperature of -5 to 5°C for cooling and shaping. Finally, the mixed liquid N is sprayed on the surface of the particles, stirred evenly, and placed in a normal temperature dryer for drying for later use.

6. A method for improving the bonding performance of HMMM resin by methylal as claimed in claim 5, characterized in that: The plasticizer is any one of epoxy vegetable oil, trimethoxysilane and polyethylene glycol.

7. A method for improving the bonding performance of HMMM resin by methylal according to claim 1, characterized in that: 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%.

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