Research On IPDI And HMDI Type All Water-based Polyurethane Flexible Foams

Currently the main raw material for preparing polyurethane foam is polyetherpolyol and aromatic diisocyanate, where the aromatic isocyanate is mainly chosentoluene diisocyanate (TDI) and4,4’-diphenylmethane diisocyanate (MDI). Thestructure of the benzene ring of the aromatic isocyanates result polyurethane foamtending to yellow and having greater toxicity, which influencesthe use ofpolyurethane foam.Using fat(cyclo) aliphatic isocyanates instead of aromatic isocyanates cansignificantly improve the polyurethane foam inadequate such as easy yellowing andtoxicity. However, foam preparation process is more complex due to the low fat(cyclo)aliphatic isocyanate activity, which leads to less research on this issue. In this paper,we select pure water as blowing agen to study isophorone diisocyanate (IPDI) anddicyclohexyl methane diisocyanate (HMDI)all water-based soft polyurethane foamformulations reaction conditions, the formulation and foam propertiest.Firstly, we research and analysis different processes of the prepolymerpreparation methods: one step and two-step prepolymer prepolymer process.Based onthe measured free isocyanate root content, one step prepolymer method lasts3h, thefirst step of thetwo-step prepolymer methodlasts3h, and the second step of thetwo-stepprepolymer method1h or15s to foam. Depending on the water-addingmethed, it is divided intotwo foam ways of mixed with water foaming process andseparate water foaming process.Dependingd on different prepolymer conditions and foaming modes, we studytheeffects of tin amine catalyst, water, isocyanate type, cell opener, chain extenderand the like factorson the foam. By measuring the apparent density, scanning electronmicroscopy performed to calculate the bubble aperture and opening rate of the bubble,we analysis and testing to get the optimal preparation methods and formulations. IPDIprecedes HMDI, and when polyether in an amount of30g, the isocyanate index1.015,the optimum formula of mixed with water foaming process is DBU0.096g, stannous octoate0.14g, water0.8-1g, silicone0.31g, sodium ethylhexanoate0.2g and cellopeners0.75g. We use excess water in separate water foaming process formulations,and the optimal formulation is DBU0.5g, stannous octoate0.05g, water6g, theamount of silicone oil, sodium ethylhexanoate and cell opener is ditto. Foam preparedby separate water foaming process is very delicate.Finally we summarize the foam defects and problems during foaming, such ashollow, shrinkage, serious side leather, coarse,foam powder, yellowing, foamviscosity, foam smoke, and analysis thereasons and improvedmethods.