Novel Polyols for All-Water-Blown Open-Cell Rigid Polyurethane Foam

HCFC-141b and Cyclopentane have been widely used as blowing agents for rigid polyurethane foam market in Japan. In the Japanese rigid polyurethane industry, HCFC-141b is very useful but considered to be the transitional blowing agent which will phase out by 2003 because of its Ozone Depletion Potential(ODP). Therefore, Hydrocarbons (HCs), Hydrofluorocarbons (HFCs) and Water are considered to be the alternatives and the new technologies for replacement have been investigated. These alternatives are all ODP free but have some serious problems respectively in the applications. Hydrocarbons, e.g. cyclo-pentane, is restricted to use only in inflammable place because of its flammability and is now used only in the appliance market. HFC-245fa, typical alternative in HFCs, is non-flammable and reported the foams blown with it have equivalent thermal conductivity to HCFC-141b blown foams, but has higher vapor pressure than that of HCFC-141b. In rigid urethane market, especially in construction market, water is considered to be the ultimate blowing agent, because of its ODP free, non-flammability, non-toxicity and easy to handle at ambient temperature. But all water blown foams have several problems to put practical use. unstable in dimensional stability high surface friability The reason of dimensional unstability is that the higher diffusion rate of CO2 to the out-side of the cell than that of air to the inside of the cell and the internal pressure of the cell decreases and foam shrinkage occurres. In order to keep dimensional stability, one of the technologies is to open the cell to diffuse CO2 and air easily. The reason of foam friability is caused by too much urea bonds contained in the matrix, formed by the reaction of H2O and Isocyanates. The key technologies to develop all-water-blown foam are thought to rupture the cell membrane to introduce flexible-bond or / and toughness-bond in the urea rich polyurethane matrix. Under these circumstances, the development of open cell technology and its applications technology for board 136 and Pour-In-Place (PIP) has been just started. But current technology can not yet solve these problems. The most important technology is to control rupturing the cell membrane under the optimum H2O level. At the optimum H2O level, water consumption efficiency becomes high and we can get both open cell and non-friable foam even at low density. In this paper, we introduce a series of novel polyols for all water blown open cell foam, WB-4500, WB4550 and WB-4600, to solve these problems. WB-4500 is designed for rapid reaction rate and suitable for 20kg/m3 density foam in the board foam market. WB-4550 is designed for higher reactivity rate than WB-4500 and suitable for lower than 20kg/m3 density foam in the board foam market. WB-4600 is designed for mild reactivity rate and makes dimensional stability foam at low molded density without foam surface friability in PIP molding.