| 摘要 |
PROBLEM TO BE SOLVED: To perfectly prevent the leakage of a synthetic resin foaming soln. by using a cylindrical hollow rubbery elastic air tube having airtightness as a plug and sensing air to the air tube under pressure. SOLUTION: In a method for producing a heat insulating panel from hard polyurethane foam, a synthetic resin foaming soln. is injected in a mold and, thereafter, an air tube 3 is inserted into an injection hole 4. Generally, the diameter of the air tube 7 is 70-90% of the diameter of the injection hole 4. A cock valve 5a is changed over by a three-way cock 5 to send air and the inserted air tube 3 is expanded to be closely brought into contact with the injection port 4 to perfectly prevent the leakage of the synthetic resin foaming soln. Therefore, the injection hole 4 can be sealed by one-action operation and, since foam does not enter the injection hole 4, cleaning work after molding is unnecessary. |
