Study On Preparation And Properities Of Two-component Polyurethane For Repairing Rubber

As one of the six synthetic materials in the world today,polyurethane(PU)has good mechanical properties,andthe materials and products are widely used in national production and life.Two-component polyurethane repair adhesive is a type of polyurethane material,the existence of urethane or urea groups in its macromolecular segments,bring it the characteristics of good toughness,low temperature resistance,wear resistance,good adhesion to the substrate interface,etc.But under the conditions of long-term heat and ultraviolet radiation,the repaired areas of the conveyer belt areliabletodeteriorate,the polyurethanefilms may become stiff,the heat resistance and hydrolytic resistanceperformance may become bad.These shortcomings limit the applicationrange of repair adhesive.Therefore,through the exploration of synthetic technology of polyurethane repair adhesives by the selection of raw materials and the analysis of fillers,etc,this paper aims to obtain a two-component polyurethane repair adhesive with excellent hydrolysis resistance,aging resistance,and high temperature resistance,thereby expanding its application field.In the third chapter,the synthetic process of polyurethane was explored firstly,afterdetermination of the process parameters,aromatic MDI-100 was used as isocyanate,and polycarbonate diol(PCDL)and polycaprolactone diol(PCL)polyol were used respectively as the soft segments for the preparation of the polyester type polyurethane repair adhesive.At first,the optimum synthesis reaction temperature was determined by di-n-butylamine method to be 75?,the reaction time was 2.5 h,and the r value(-NCO :-OH)in the prepolymer was 4.After the synthesis process was confirmed,the effects of isocyanate index,curing time and catalyst addition on the properties of the two-component polyurethane repair adhesive were investigated.The results showed that the mechanical properties of the repaired polyester polyurethane adhesive were the best when the isocyanate index R was 1.10.TheT-type peel strengths of PCDL-type and PCL-type repair adhesives have the maximum value of 7.8 k N/m and 7.2 k N/m respectively;and the maximum shear strengths were 8.6 MPa and 7.8 MPa,when the coating ratio of prepolymer and curing agent(A/B mass ratio)is 3.5:1.Based on the R=1.10 test formulation,the hydrolysis resistance and high temperature resistance test of the repair adhesive showed that the PCDL polyurethane was superior to the PCL adhesive;longer curing time may contributed to better properties of the repair adhesive,and the repair adhesive would completely cured after 48 hours of curing.The addition of the catalyst would accelerate the curing speed,but it might damage the adhesive properties of the repair adhesive.Based on the previous experiments,the fourth chapter synthesized a polyether polyurethane repair adhesive with excellent overall performance.The effect of silica addition on its performance was studied,and the hydrolysis resistance of polyether polyurethane repair adhesive was studied comparing with the polyester-based polyurethane repair adhesive.The results showed when the amount of white carbon black was 6%,the maximum tensile strength of the repair adhesive was 18.9MPa,the maximum peel strength and tensile shear strength were 7.4k N/m and 8.1MPa respectively,and the bonding failure mode was cohesive,and the stability of heat resistance is also improved obviously.The hydrolysis resistance test showed that the polyether type polyurethane repair adhesive had a comparative excellent water resistance,while compared with the polyester repair glue in same conditions,the adhesive properties and water resistance of polyether type polyurethane repair adhesive were a bit poor.The polyester-based aliphatic polyurethane repair adhesives synthesized with IPDI and PCDL as raw materials,have relatively stable adhesive properties,excellent hydrolysis resistance and high temperature resistance.The yellowing resistance test of aliphatic and aromatic polyurethane repair adhesives showed that the aliphatic polyurethane repair adhesive had better yellowing resistance than the others.