| 摘要 |
PROBLEM TO BE SOLVED: To provide a foaming starting pressure measuring method, with which the foaming starring pressure of a mixture of an arbitrary resin and a foaming agent can be accurately measured. SOLUTION: In a flow passage, through which a mixture formed by melting the foaming agent is a thermoplastic resin passes when the mixture in homogeneous phase, prepared by heating and melting the thermoplastic resin and the foaming agent melted so as to melt the foaming agent in the thermoplastic resin under pressure is extruded in a lower pressure part, a first means for detecting the foaming starting position due to the absence and presence of the development of bubbles in the flow passage, a second means for controlling the foaming starting position at the desired position in the flow passage and a third means for measuring the pressures at 1 or 2 or more points in the flow passage are provided so as to measure the foaming starting pressure of the mixture prepared by melting the foaming agent in the thermoplastic resin by utilizing the foaming starting position measured by the first means and the pressures at 1 or 2 or more points in the flow passage measured by the third means under the state that the foaming starting position is controlled at the desired position in the flow passage by the second means. |
