PURPOSE: To prepare a urethane-based water-proofing material having high safety and excellent heat stability and weatherability, by using a pitch as a dispersing agent in a urethane-based composition composed of a urethane prepolymer, a curing agent, a CO2 gas-absorbing agent, and a dispersing agent.
CONSTITUTION: The title composition is prepared by compounding (A) (pref. 25W50% of) a urethane prepolymer [pref. containing 2W7wt% of isocyanate group (-NCO group)], with (B) (pref. 50W75% of) a curing composition containing (a) 3W20% of a curing agent (e.g. polyether polyol), (b) 5W50% of a CO2 gas- absorbing agent (e.g. Ca(OH)2), and (c) 5W50% of a dispersing agent (pref. a hard pitch such as coal tar pitch). The components (a) to (c) are mixed together before compounding to the (A) component.
USE: Protection of building walls, such as concrete wall, mortar wall, etc. exposed to rain.
ITOU TOSHIHIKO
TANUMA TSUNEO
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