Patent ID: 7875253

Claim:
A start-up method for a decomposing system for decomposing polyisocyanate residues to polyamine using high temperature and high pressure water, the decomposing system comprising a decomposing tank for allowing the polyisocyanate residues and the high temperature and high pressure water to contact with each other, a water feed pipe connected to the decomposing tank for feeding the high temperature and high pressure water to the decomposing tank, and a residual feed pipe connected to the water feed pipe for feeding the polyisocyanate residues to the decomposing tank together with the high temperature and high pressure water, wherein a solvent is previously filled in a connecting portion of the residual feed pipe with the water feed pipe, then, the high temperature and high pressure water is fed from the water feed pipe to the decomposing tank, then, the solvent is fed from the residual feed pipe to the water feed pipe, first, and then, the polyisocyanate residues are fed thereto.