METHOD FOR PREPARING POLYIMIDE MATERIALS Russian patent published in 2005 - IPC

FIELD: polymers, chemical technology.

SUBSTANCE: invention relates to a method for preparing polyimide materials. Method involves heating polyamidoacid solution and the imidization process is carried out in regimen of step-by-step increase of temperature followed by keeping. Heating is carried out by effect of ultra-high frequency radiation with power Pi value of that is adjusted at each step as a measured value and determined by the following dependence: P_{i min} = (λ_p x m_i + C_p x (M - ) x ▵T_i)/t_i wherein I is an ordinal number of step; i = 1 ...... N; N - number of steps; λ_p - heat of phase transfer of solvent, J/kg; m_i - solvent mass evaporated at 1-th step, kg; C_p - specific heat of base, J/kg x °C; M - base mass at initial step of imidization, kg; ▵T_i = T_i - T₀ wherein T_i - keeping temperature at i-th step, °C; T_o - temperature of base before onset of imidization process, °C; t_i - keeping time at i-th step, c. The imidization process is terminated additionally by UV-irradiation at wavelength λ = 240-400 nm. Invention provides reducing the imidization process period and to reduce cost of polyimide materials. Polyimide materials can be used in aviation, automobile manufacture, ship building, building industry and in manufacturing strength fire-resistant polyimide materials as films, foam plastics, powders.

EFFECT: improved preparing method.

2 cl, 4 tbl, 3 ex