| 摘要 |
A method for continuously preparing solvent-free open-cell and closed-cell polyimide foams, firstly, one or a few of dianhydrides dissolve in or suspend in the polyhydric alcohol and form the precursor A. All kinds of additives dissolve in the polyhydric alcohol and form the precursor B. The aromatic isocyanates with different structure mix well and form the precursor C. Finally the three precursors are mixed foaming by one-step, after solidify, the polyimide foams are obtained with advantage performance. The method does not utilize the volatile solvent that does not participate in the reaction, therefore not existing the process of removing the solvent, it can continuously produce with the double-side heat conveyor belt. CO2, the main gas producing in the reaction, causes the system to foam, thus there is no cost on the solvent recovery and it reduces the environment contamination. |
| 主权项 |
1. A method for continuously preparing solvent-free open-cell and closed-cell polyimide foams, the method comprising:(1) preparation of precursors,
preparation of a precursor A: firstly heating polyhydric alcohol and solution polar cosolvent to a temperature of 40° C.±5° C. in a reactor, then adding aromatic dianhydride thereto and mixing them well, then increasing the inner temperature of said reactor to 140° C.˜180° C. and keeping said temperature until said polar cosolvent therein is completely volatilized, and finally the precursor A being obtained; the quality of said aromatic dianhydride added in being 75%˜150% of that of said polyhydric alcohol; preparation of a precursor B: according to mass portion, 100 portions of polyethylene glycol, 20˜200 portions of water, 0.1˜20 portions of catalyst, and 2˜30 portions of surfactant being mixed well, and then said precursor B being obtained; a precursor C being selected from a group consisting of diphenyl-methane-diisocyanate (MDI), toluene diisocyanate (TDI), 1,6-diisocyanatohexane (HDI), isophorone diisocyanate (IPDI), and any combination thereof;(2) foaming,
dynamically mixing said precursor A, said precursor B, and said precursor C in mass ratio 3.1˜11.4:1:6.3˜14.3, at the same time, a foaming agent being added thereto, mixing speed thereof being in a range of 1200˜2500r/min, and said precursor A being heated to a temperature in a range of 40° C.˜50° C. before mixing;(3) solidification,
a material, obtained in the foaming process by the dynamically mixing of said precursor A, said precursor B, said precursor C, and said foaming agent, being injected into a continuous transmission double-side conveyor belt and then solidified to obtain the polyimide foams. |
