Synthesis Of Waterborne Polyurethane Material Based On Poly(Propylene Carbonate)

Waterborne polyurethane (WPU) is a kind of polyurethane material using water as dispersion medium. It not only has excellent comprehensive performance, but also has the characteristics of environmental friendly and safely. Therefore, waterborne polyurethane material has attracted more and more attention. At present, the main polyols material for the synthesis of waterborne polyurethane is polyether and polyester polyols. However, WPU based on polyether polyols has poor mechanic strength and WPU based on polyester polyols has poor hydrolysis resistance. WPU based on PTMEG and PCDL has excellent comprehensive properties, however they are too expensive for large-scale application.Poly(propylene carbonate) polyols (PPC) can be produced by the copolymerization of propylene oxide and CO2 using double metal cyanide catalyst(DMC). This method supplies a new method for preparing aliphatic polycarbonate polyols with low cost and excellent properties. In this paper, characteristic of PPC based on a new kind of DMC, which was developed by our team, is studied in detail. WPU based on this PPC is prepared, factors, which influenced the properties of WPU, is explored in this paper and based on this WPU with excellent mechanic and strength hydrolysis resistance is obtained. The results were listed as follows:1.PPC, which can be prepared by copolymerization of propylene oxide and CO2, is a random copolymer and it has excellent thermal stability. TGA shows initial decomposition temperature of PPC is 279 ℃ and thermal decomposition temperature decreases slightly with the increase of COO content in PPC.2. PPC has poor crystallinity and it is rather viscous syrupy liquid under normal temperature. Glass transition temperature and viscosity increase with COO content in PPC increasing.3. Hydroxyl value of PPC can be accurately measured by 1-Methylimidazole- Acetic anhydride -DMF method4. PPCWPU was prepared by pre-polymerization method and influence factors were studies in this paper. Results show that the perfect synthesis condition is:reaction temperature,70-80℃, reaction time,3-4h, the amount of catalyst,0.7%, isocyanate index value,1.5, dosage of DMPA,5%.5. Initial thermal decomposition temperature, tested by TGA and DSC method, of PPCWPU was 271 ℃ and glass transition temperature, tested by TGA method, was-17.9 ℃. XRD and DSC show that PPCWPU has poor crystallinity comparing to PBAWPU and PCDLWPU, but better than PPGWPU. DSC also shows that it has an obvious peak at 40℃, which is similar to PCDLWPU and PBAWPU.6. PPCWPU has excellent mechanical properties, mechanical strength increased and elongation at break decreased with the increase of COO content. When COO content of PPC is 24%(mole), PPCWPU has similar elongation at break and two times tensile strength comparing to PPGWPU. When COO content of PPC is 31%(mole), PPCWPU has similar tensile strength and much higher elongation at break comparing to PBAWPU.7. By product of PC in PPC has no obvious effect on the stability of one component polyurethane adhesive. But when calcium carbonate or other alkaline substances was added to the one-component polyurethane adhesive, the viscosity raised rapidly under 80℃ condition. PC would decompose and release CO2 under alkaline conditions, which affected the storage and transportation of WPU.