An Aluminum Electrolytic Capacitor Working Electrolyte Additives Preparation And Research

Polyethylene glycol carboxylic ester is a kind of multi-purpose macromolecule polymer. It has the widespread application in the chemical industry. In this dissertation, the most superior synthesis craft of polyethylene glycol 400 succinic acid ester (PEGS) was systematic researched. The physical and chemical properties and structure of PEGS obtained were tested and characterized. The influence of PEGS on the property of working electrolyte were investigated . Subsequently, we studied the application of PEGS in aluminum electrolytic capacitor. The main content of the article are as follows.Under the condition of no catalysis and negative pressure, PEGS was synthesised by using the solvent direct esterification law and PEG(400) and succinic acid as raw material. The factors such as raction temperature, raction time and raction negative pressure on the esterification were investigated. Through the esterification rate, the acid value and mean molecular weight of product, the acid glycol molar ratio of raction was determined. The results show that the esterification rate of raction reached 98.81% at the best condition of raction temperature was 160℃, raction time was 4 h, raction negative pressure was 15 KPa, acid glycol molar ratio was 3:2.Using NDJ-1 rotary viscosimeter, KF-ⅡMicro moisture apparatus, HG/T 2708-1995, FT-IR and TG, the physical and chemical properties and structure of PEGS were tested and analyzed. The results show that the two terminals of synthesized PEGS are carboxyl groups, its viscosity is 120 mPa·s, water content is 0.83%, acid value is 103.5mg KOH/g. The thermostability of PEGS is quite good with the temperature of its 1.4%weight loss is 185℃,and PEGS has not been degraded completely until the temperature reaches to 430℃or so. The PEGS is applicable to the working electrolyte for aluminum electrolytic capacitor, the operating temperature of which is lower than 150℃.Adding the synthesized PEGS to the working electrolyte for aluminum electrolytic capacitor, the influence of the addition and the pH value of prepared PEGS on the sparking voltage, electric conductivity of the working electrolyte for aluminum electrolytic capacitor were investigated. The results show that the PEGS can improve the sparking of the working electrolyte, and can also restrain the electric conductivity reduction effectively. With mass fraction of 3% addition, the sparking voltage of the working electrolyte can be increased by 45V at most, the electric conductivity only be deceased about 100×10^-6S/cm. The best pH value of PEGS as additive is 6.0.With appling the working electrolyte which contains the synthesized PEGS in the aluminum electrolytic capacitor, we research its capacitance, leakage current, loss tangent, life and other properties by length of life test. The results show that, after adding the PEGS, the capacitance and leakage current of aluminum electrolytic capacitor is small, as well as the rate of chang of capacitance and leakage current reduces. The synthesized PEGS can enhance the aluminum electrolytic capacitor's thermostability and lengthen it's life. Under 35℃of room temperature, the aluminum electrolytic capacitor's life may amount to for 140 years.