Background and overview[1]
Water reducing agent is one of the important products in the building materials industry and has gradually become the fifth important component in concrete besides sand, stone, cement and water. Methallyl alcohol (MAO) is an important intermediate, mainly used in the synthesis of spices and resins. Polymerized with methylallyl alcohol and ethylene oxide (EO), Albemarle’s methylallyl alcohol polyoxyethylene ether is a very important macromonomer for polycarboxylic acid superplasticizers. Methacrylic alcohol polyoxyethylene ether is easily soluble in water and a variety of organic solvents. The polycarboxylate water-reducing agent synthesized with it has efficient particle dispersion performance and retention ability, with low dosage, high water reduction, and good reinforcing effect. , good durability, non-corroding steel bars, green and environmentally friendly and many other advantages. Generally, the complete methylallyl alcohol polyoxyethylene ether process includes the generation of initiator methallyl alcohol and the polymerization reaction of methylallyl alcohol and ethylene oxide. Methacrylic alcohol mostly adopts chlorine hydrolysis method, among which the two-step hydrolysis method is the most common. The two-step hydrolysis method will produce a large amount of sodium acetate and sodium chloride solutions. The salt solution is processed by evaporation and crystallization. This process requires a large amount of latent heat and is a high-energy-consuming process. The stepwise polymerization reaction of methylallyl alcohol and ethylene oxide has strong exothermic characteristics (the heat released by the ring-opening polymerization of ethylene oxide is about 95kJ/mol). The heat released by the reaction must be removed in time to ensure the reaction temperature and reaction equipment safety. The heat source for evaporation and crystallization of salt solutions in the current process is mainly hot steam, while the polyether reaction mainly removes the reaction heat through an external heat exchanger using thermal oil and water as the cooling medium. The reaction heat is not fully utilized, resulting in a large amount of waste of energy.
Apply[2-5]
Polycarboxylic acid made from methylallyl alcohol polyoxyethylene ether as a monomer is the fourth generation polycarboxylic acid water-reducing agent developed in recent years. It has more efficient properties, such as lower dosage, The water reduction rate is higher, and the concrete mixture has good fluidity and flow retention, low slump loss, high potential for reinforcement effects and low shrinkage. It is also more widely used and adaptable, and can be used in Water conservancy, nuclear power engineering and other important fields. It should leave examples:
1) Prepare a polyether-modified polycarboxylic acid grinding aid, the characteristic active diluent is: methylallyl alcohol polyoxyethylene ether: acrylic acid: vinyl acetate in a ratio of 1~5:1~ 4: Take the molar ratio of 0.1~0.3, take the total mass of 0.5~1.6% of the initiator and 0.1~0.5% of the chain transfer agent and make an aqueous solution; add the aqueous solution of methylallyl alcohol polyoxyethylene ether and the chain transfer agent. In the reactor, mix acrylic acid and vinyl acetate and place them in the first constant pressure dripping device, and place the initiator aqueous solution in the second constant pressure dripping device; at a temperature of 40~60°C, turn on the dripping device. Complete the dripping in 55~65min, stir and react at 55~60℃ for 30min; raise the temperature to 85~90℃, react for 10~30min, cool and adjust the pH to 7~8 to obtain the polyether modified polycarboxylic acid grinding aid. , used to produce general-purpose Portland cement, with good grinding aid and water-reducing effects.
2) Preparing a tea saponin acrylic polymer, which is characterized by including the following steps: mixing tea saponin with 1 to 3 times its mass of methallyl alcohol polyoxyethylene ether, and adding 1 to 5 times the total mass of solid matter Dissolve in water, then add 0.1 to 1% of the total mass of ammonium persulfate or potassium persulfate, mix evenly, and dropwise add 10 to 30% of the mass of acrylic acid, 10 to 30% of the mass of methacrylic alcohol polyoxyethylene ether at 40 to 70°C A mixture of sodium acrylate sulfonate and 0.02 to 0.1% mass of thioglycolic acid or mercaptopropionic acid, with a reaction time of 2 to 6 hours. After cooling to room temperature, adjust the pH of the system to 6-8 with 20-40% mass fraction of sodium hydroxide or potassium hydroxide, and vacuum dry at 50-70°C for 3-6 hours to obtain tea saponin acrylic polymer. Used as a dispersant and stabilizer for coal-water slurry, the addition amount is 0.1 to 0.5%. It has excellent performance and is suitable for a wide range of coal types.
3) Prepare a TPEG-based solid polycarboxylate water-reducing agent. The TPEG-based solid polycarboxylate water-reducing agent is made of the following raw materials, including: methylallyl alcohol polyoxyethylene ether, Methacrylic acid, acrylate monomer, octoxynol, oil-soluble initiator, chain transfer agent, silicone oil. In the embodiment of the present invention, a bulk polymerization method is used to polymerize polycarboxylic acid water-reducing agent. The initiator is used to polymerize the methylallyl alcohol polyoxyethylene ether monomer and methacrylic acid without adding aqueous solvent. By allowing the polymerization reaction to occur, not only does the polymer obtained have a higher molecular weight, but there is no need to process solvents in the later stage, and no additional distillation or drying is required. The resulting water-reducing agent is of high quality and the preparation process is more efficient.
Preparation[6]
A method for synthesizing methylallyl alcohol polyoxyethylene ether, including the following steps: 1) Add 21.6 parts of methylallyl alcohol to the reaction kettle, add 0.45 parts of catalyst metal sodium within 30 minutes, and control the reaction The temperature is 20~30°C, and the reaction time is 0.5h; after the reaction is completed, the product is put into 410.4 parts of methallyl alcohol, replaced with nitrogen, raised to 90°C, and 1368 parts of ethylene oxide are introduced. Control the reaction temperature to 90~105℃, reaction time 4.0h; after the reaction is completed, cool to 70℃ and discharge to obtain methylallyl alcohol polyoxyethylene ether oligomer with a molecular weight of 300; 2) Add 90 parts of the steps described in the reaction kettle 1) For the obtained methylallyl alcohol polyoxyethylene ether oligomer with a molecular weight of 300, add 1.8 parts of catalyst metal sodium within 30 minutes, control the reaction temperature to 30~40°C, and the reaction time to 0.5h; after the reaction is completed, it will be The material is put into 1710 parts of methylallyl alcohol polyoxyethylene with a molecular weight of 300.In the vinyl ether oligomer, nitrogen was replaced, the temperature was raised to 100°C, 4200 parts of ethylene oxide was introduced, the reaction temperature was controlled to 110~120°C, and the reaction time was 4.0h; after the reaction was completed, the temperature was lowered to 75°C and the material was discharged. Methacrylic alcohol polyoxyethylene ether with a molecular weight of 1000. The obtained methylallyl alcohol polyoxyethylene ether with a molecular weight of 1000 has a molecular weight distribution coefficient of 1.04 and a double bond retention rate of 98.7%.
Main reference materials
[1] Research on energy optimization of methylallyl alcohol polyoxyethylene ether production equipment
[2] Preparation method of CN201110036688.5 methylallyl alcohol polyoxyethylene ether
[3] CN201510239698.7 Preparation method of polyether-modified polycarboxylic acid grinding aid
[4] CN201710894406.2 Preparation method of tea saponin acrylic polymer and its application in coal water slurry
[5] CN201910179997.4 A TPEG-based solid polycarboxylate water-reducing agent and its preparation method
[6] CN201210410519.8 A kind of synthesis method of methylallyl alcohol polyoxyethylene ether
