Study Of Producing Of Glass Fiber Flexible Insulating Sleeve With UV-curing Technology

Glass fiber flexible insulating sleeve is a basic industrial product but with the pressure totechnological innovation, energy conservation and emission reduction. UV curing coating hasthe nature of environmental, energy-saving and energy-efficient properties, hopefully willreplace the traditional insulating varnish. However, to reduce the viscosity of the UV formulation,amounts of reactive diluent would be added to the formulation in the sacrifice of the propertiesof the film. Hyperbranched polymers, a novel type of polymers, with unique physical andchemical properties, such as low viscosity, good rheological property and numerous activeterminal groups, maybe can solve this problem.Firstly, the effect of commercialized UV-curable hyperbranched polymers (CN2302andCN2303) on UV formulations was researched, the result showed that adding20w%of thehyperbranched polymers to the formulation had contributed to the reduction of the viscosity,improved withstand voltage from18.21kV/mm to28.22kV/mm and29.22kV/mm, increasedhardness of the UV-cured film from3H to7H, increased the UV-curing contents or gel contenthigher than90%from73.2%. However, excess amounts of HPs would lead to the brittle of thefilm, the flexibility decreased from degree7to degree2. So, it is necessary to enhance theflexibility of the hyperbranched polymers on the basis of maintaining its UV-curable property.Secondly, hyperbranched poly(ester-amide)s (HPs) with terminal hydroxyl was synthesizedbased on succinic anhydride and diisopropanol amine, and then was modified by terminalmodifying agent with unsaturated group, exp. oleic acid, crylic acid and eleostearic acid，toincorporate unsaturated bond and flexible chains. The synthesis process was monitored bydeterminnation of acid value and hydroxyl value; the modifing process and properties of the HPsbefore and after modification were tesed by FT-IR, GPC-RI-MALLS. The results indicated thatthe Mn of the HPs with terminal hydroxyl was3.717×103g/mol, oleic acid value was252mgKOH/g, each HP molecule approximately had16.4hydroxyl groups. The HPs with terminalhydroxyl can be modified with varying amount of oleic acid, after modification, the productscan’t be UV-cured. Besides, said HPs with terminal hydroxyl modified by crylic acid oreleostearic acid didn’t show UV-curable probablity. Then, to improve UV photoactivity of the product, maleic anhydride and diisopropanolamine was used to synthesize unsaturated hyperbranched poly(ester-amide)s (UHPs) withterminal hydroxyl, oleic acid, crylic acid and eleostearic acid were used as modifier. Theinstruments mentioned above were applied to monitor and test the UHPs before and aftermodification. The result showed that Mn of the UHPs with terminal hydroxyl was3.486×103g/mol, oleic acid value was210.1mgKOH/g, each HPs approximately had13hydroxyl groups.UHPs modified with crylic acid had UV-curable property, the gel rate of its UV-curing film was93.2%, but the film was brittle, flexibility testing was degree1, hardness was5H. The UHPswith terminal hydroxyl modified by long chain modifiers with saturated bond, such as oleic acid,eleostearic acid, didn’t show obvious UV-curable property.At last, through the redesign of the UV-curing device, introduction of the heating coatingunit and semielliptic single-light source to several-sleeve system, the problems such as highviscosity，low UV curing efficiency could be solved, the product-UV curing glass fiber flexibleinsulating sleeve was successfully produced. The product passed the test of CEMT, its bendingproperty surpassed the demand of GB/T7113.2-2005, breakdown voltage at room temperature(23℃) could reach8.2kV, twice higher than the requiring.