Supercritical extraction with carbon dioxide and ethylene of poly(vinyl butyral) and dioctyl phthalate from multilayer ceramic capacitors

Supercritical extraction with carbon dioxide and ethylene at 35–75 °C and 10–40 MPa was used to remove binder and plasticizer from multilayer ceramic capacitors (MLCs) having BaTiO3 as the dielectric and Pt as the electrode material. The organic phase consisted of poly(vinyl butyral) (PVB) and dioctyl phthalate (DOP) in the weight ratio of 55:45 present as 10% initial body weight. With supercritical CO2 or C2H4 at 75 °C and 40 MPa, 50.2 and 41.4% by weight of the total organic phase, respectively, were extracted from the MLC substrates in 3 h. Use of methanol as an entrainer at the same conditions led to almost no change in extraction in CO2 and to 50% extraction in C2H4. When films of PVB and DOP (without BaTiO3 and Pt) were subjected to the same extraction conditions with methanol, 63.4% of the organic phase was removed in supercritical C2H4 as compared to 52.6% in supercritical CO2. Evidence is also presented for interactions between DOP and PVB and BaTiO3. The degree of swelling of DOP+PVB films in both the supercritical solvents was also examined as a function of temperature and pressure.