Preparation, characterization, and continuous manufacturing of nonflammable colorless and transparent semi-alicyclic polyimide film modified with phenoxy- phosphazene oligomer flame retardant

Abstract

Phenoxy-phosphazene (PPZ) oligomer (Rabitle® FP100) flame retardant (FR) was successfully incorporated into the colorless and transparent semi-alicyclic polyimide (CPI) film matrix derived from 1,2,4,5-cyclohexanetetracarboxylic dianhydride (CHDA) and 4,4′-oxydianiline (ODA) (PI-a, CHDA-ODA). The PPZ FR showed good miscibility with the PI-a matrix with a loading amount of up to 10 wt% in the composite films. PI-b (CHDA-ODA-FP100-5) film maintained good optical properties with the transmittance of 83.9% at the wavelength of 400 nm, the yellow index (b*) of 3.28, and the haze of 2.14%. PI-b film also showed good flame retardancy with the limiting oxygen indices (LOI) of 41.2% and the flammability rating of UL94 VTM-0. In addition, PI-b film exhibited the obviously reduced heat release rate (HRR) and total smoke production (THR) during the cone calorimeter measurement. At last, PI-b showed the glass transition temperature (Tg) and 5% weight loss temperature (T5%) of 325.0 and 404.3 °C, respectively, which was slightly lower than those of the pristine PI-a film (Tg = 346.8 °C; T5% = 431.6 °C). Continuous PI-b films with a length of 1000 m and a width of 1000 mm were successfully obtained on the demonstration production line by optimizing the processing parameters via the modified solvent cast technology. Similar thermal, optical, and flame retardancy properties and obviously improved tensile properties were observed for the mass production of PI-b film.

Keywords

• polymer composites
• semi-alicyclic polyimide
• colorless polyimide film
• flame retardancy
• phosphazene oligomer