Preparation And Modification Of The Heat And Hydrolysis Resistant Polyurethane Adhesive

Reaction of polyurethane adhesive with active hydrogen containing materials such as paper,wood,metal,glass,rubber and so on bring excellent chemical bond strength,which is widely used in construction,military,aerospace,industrial manufacturing,medicine,textiles and other fields.However,it is easy to reduce the mechanical properties,the heat resistance and hydrolysis resistance is insufficient at high temperature,moisture and other special circumstances.In this paper,the properties of polyurethane are improved from the aspects of raw material,process angle,and modified chain segment,which makes the performance of polyurethane adhesive be better and the application be more extensive.The polyurethane adhesive was modified from its constitution,the ratio of raw material to curing agent,soft and hard segment.And the preparing recipe and technological conditions were optimized.The resultant polyurethane was characterized by Fourier transform infrared spectroscopy(FT-IR),thermogravimetric analysis(TGA)and contact angle.The performances such as peel strength,water absorption,water resistance and heat resistance were tested.The effect of its constitution,the ratio of raw material to curing agent,various modifiers and their content on the properties of polyurethane materials were investigated in detail.The optimized formulation of raw materials is obtained by experiment: 149.91 g diethylene alcohol,343.32 g neopentyl glycol,389.53 g 1,6-hexanediol,87.69 g ethylene glycol,456.36 g benzene dicarboxylic acid,195.58 g terephthalic acid,555.58 g sebacic acid,172.05 g adipic acid,0.5g tetra ISO propyl titanate.The optimal ratio of the main agent and curing agent is 5:1,and the R=1.65;The best curing time and curing temperature is 48 h and 55? respectively.First,the phthalic anhydride was used as polymerization material to modify the soft segment.Second,the modified polyurethane was synthesized by the polyester polyol and modified isocyanate,which was prepared with silicone and isocyanate.Third,the polyurethane was modified when organic fluorine was used as blocking agent which reacted with some of prepolymer termination of isocyanate end groups.Successfully modifiers into the polyurethane main molecular chain,and the optimal addition amount of MNPOP,phthalic anhydride,silicone oil,is 3%,10%,1.5% respectively.Results from the study show that,the heat resistance and hydrolysis resistance of the modified polyurethane adhesive were improved on the basis of maintaining the original mechanical strength.