| 摘要 |
PROBLEM TO BE SOLVED: To obtain a cleaning liquid that has a good cleaning effect on polyurethane resins, particularly polyurethane resin compositions, and is less smelly, less toxic, and excellent in safety by incorporating a specified amount ofγ- butyrolactone. SOLUTION: This cleaning agent for polyurethane resins contains 70 to 100 pts.wt.γ-butyrolactone (GBL) and 30 to 0 pts.wt. water. The mixing ratio of GBL to water is preferably such that 80 to 100 pts.wt. GBL is mixed with 20 to 0 pts.wt. water from the viewpoint of the cleaning effect. If the amount of GBL is less than the lower limit and the amount of water is over the upper limit, the solvency for polyurethane resins and polyurethane resin compositions is lowered considerably and a good cleaning effect cannot be obtained. When the amount of GBL is 90 pts.wt. or less and the amount of water is 10 pts.wt. or more, the resultant cleaning liquid does not have any flashpoint and does not fall in the category of dangerous goods as defined in fire regulations, which is preferable in view of the safety. Since this cleaning liquid is high in penetrability into urethane resins and can cause urethane resins to swell and to be removed, the cleaning liquid can clean and remove urethane resins wherein reactions have proceeded to form gels or prepolymers.
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