Preparation And Properties Of Latent Curing One-component Polyurea

Polyurea material has high abrasion resistance,good anti-seepage effect,low water absorption and excellent mechanical properties,which are widely used in waterproof in construction and water conservancy projects.Because the traditional one-component polyurea is based on the principle of moisture curing,it is easy to generate bubbles during curing.In order to solve this problem,a latent-curable one-component poly urea was synthesized.In this paper,the polyure was synthesized based on polytetrahydrofuran ether glycol(PTMPG),toluene diisocyanate(TDI)and oxazolidine-based latent curing agent(BHD-808),which was synthesized by the prepolymer method with high strength,hydrolysis resistance and heat resistance to meets the actual needs.The effect of proportion of combined polyether polyol,isocyanate type,isocyanate index(R value),NCO content and NaYF4 modification on the structure and performance of latent curing type one-component polyure was evaluated through infrared,curing time,crosslink density,room temperature water absorption,mechanical properties,hydrolysis resistance,and heat resistance test.The concludeds are as follows:(1)By screening polyols,isocyanates,latent curing agent types and adjusting poly urea parameters(R value and NCO content),a series of one-component polyureas were prepared.The final determination of PTMPG,TDI and BHD-808 as the main raw materials,when the R value is 0.95,NCO content is 7%,the performance of the latent curing type one-component polyurea material is the best Better.At this time,a crosslink density of the latent curing type one-component polyurea is 1.7×10-3 mol·cm-3,a water absorption rate is 3.98%,a tensile strength is 32.1 MPa,an elongation at break is 210%,the hardness is 80 Shao A,the bonding strength is 7.3 MPa,the tensile strength retention rate is 52.63%after soaking in water of 70? for 28 days,and the tensile strength retention rate is 61.71%after soaking in 0.1 mol/L NaOH solution of 70? for 28 days.(2)Compared with pure polyurea materials,the mechanical properties,hydrophobic properties and heat resistance of NaYF4/polyurea composite materials are improved,and it has the fluorescent properties that pure polyurea materials do not.And as the content of NaYF4 in the composite increases,the tensile strength,elongation at break,water contact angle,fluorescence intensity and heat resistance of the polyurea increased gradually.When the content of NaYF4 was 0.8%,the tensile strength of NaYF4/polyurea composites increased by 99.3%,the elongation at break increased by 25.3%,and the contact angle reached 90°.