Fabrication of hydroxylated boron nitride printing pastes and their application in low-temperature thermal transfer printing on polyester substrates

Thermal transfer printing of polyester requires high temperature. Sodium hydroxide (NaOH) was used to modify boron nitride (BN) through exfoliation under high temperature conditions, resulting in the formation of BNOH, which creates a better thermal conductivity pathway by changing the morphology and size of BN. This modified BNOH was introduced into the preparation of new thermal transfer printing pastes for polyester fabrics, which can effectively reduce the energy consumption and improve the color yield of the printed fabrics. The results showed that the thermal conductivity of F-PVA/BNOH films, prepared by blending polyvinyl alcohol with BNOH, was 2.279 W·m -1 ·K -1 , which was 17.4 % higher than that of F-PVA/BN films when the filler content reached 8 %. Meanwhile, the viscosity of P-PVA/BNOH paste was 383 mPa·s, which was 31.3 % lower compared with that of P-PVA/BN paste. The K/S value of the fabrics printed with P-PVA/BNOH paste was higher than those printed with P-PVA/BN and P-PVA, and P-PVA/BNOH paste could reduce the transfer temperature by about 10 °C and the transfer time by at least 15 s. The optimal process conditions for thermal transfer printing are 8 % BNOH content, a transfer temperature of 190 °C and a transfer time of 40 s. The change rate of line width in the three colors remained below 9 %, and the color fastness of the printed fabrics was not affected. The development of new paste reduces the printing temperature and improves the overall printing effect of polyester fabrics, which is in line with the eco-friendly principle of green production and environmental protection.