Synthesis and Formulation Example of Polyvinyl Acetate Emulsion Adhesive (2)
(4) Polyvinyl acetate emulsion synthesis operation method Preparation of polyvinyl acetate emulsion can be synthesized by chemical method and short irradiation method. The size of the emulsion particles obtained by irradiation method is not uniform, and the equipment requirements are high, so it is generally not used. method. Only the chemical method is introduced here. The chemical method has two modes of intermittent operation and continuous operation. The following describes the specific manufacturing processes.
1 continuous emulsion polymerization
a. Measure deionized water and polyvinyl alcohol (PVA) into a dissolution vessel, pass steam through the jacket of the dissolution vessel, raise the temperature to 80~85°C, stir and dissolve for 4~6h, completely dissolve the PVA, Duplicate 10% (mass) PVA solution.
b. After the 10% (mass) PVA solution was filtered, it was put into the polymerization tank together with the OP-10. Stir and stir to make it fully mixed, and then put vinyl acetate (about 1/7 of the total amount) and 10% (mass) of potassium persulfate solution (about 2/5 of the total) in the metering tank into the polymerization tank. Stir and emulsify for 30 minutes.
c. Pass the steam into the jacket of the polymerizer, raise the temperature of the material in the kettle to 60-65°C, and stop heating. At this point, the polymerization reaction begins. Because the reaction is exothermic, the temperature in the kettle rises automatically, reaching 75~85°C. At this point, reflux occurs in the reflux condenser. When the reflux is reduced, it starts to flow through the metering tank to the polymerization reactor. Ethyl acetate was added, and potassium persulfate solution was added dropwise through the metering tank [4% to 5% (by mass) of potassium persulfate per hour]. The control of the dropping rate kept the polymerization temperature at 78~80°C, and the dropping was completed in about 8 hours.
d. After the monomers are added, add all remaining potassium persulfate solution to terminate the reaction chain. After all the materials are added, the temperature is automatically raised to 90-95°C and incubated for 30 minutes.
e. Cool the product to 50 °C with cold water in the jacket of the polymerizer. Add the required amount of sodium bicarbonate solution and DBP additive through the metering tank, mix thoroughly, and filter and discharge.
7 batch emulsion polymerization
a. Add PVA and water to the dissolution vessel and raise the temperature to 80~85°C. Dissolve and stir for 2 h to make a 10% (mass) PvA solution.
b. The PVA aqueous solution is filtered and put into a polymerization tank, and OP-10 and the base monomer vinyl acetate [about 14% (mass) of the total monomer and 10% (mass) of ammonium persulfate aqueous solution] are added. 40% (mass) of total volume]. Close the feed hole and open the cooling water. The temperature is raised to about 65°C within 30mm. When the lens drops, the heating is stopped and the temperature rises to 75-85°C.
c. When the reflux is normal, vinyl acetate monomer is added dropwise (about 8-9 hours). Add 4% to 5% by mass of ammonium persulfate per hour, and control the uniform polymerization by adjusting the addition rate. The reaction temperature is controlled at 75-80°C and can be adjusted by the amount of monomer added.
d. After adding the monomers, add the remaining ammonium persulfate. The temperature of the liquid material rises to 90-95°C, and the temperature is kept for 30 minutes. Cool to below 50°C and add 10% (mass) sodium bicarbonate solution.
2 Polyvinyl acetate emulsion adhesive formulation example
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