Fabrication of Silk Resin Sheets Using a Hot-Rolling Equipment

Abstract

We attempted to fabricate silk resin sheets from silk powder using a hot-rolling equipment for continuous production. Silk powder was mixed with water, wrapped in a packaging material, and then passed through the nip between the heated rollers. Pulp sheet was suitable for the packaging material, while no resinification was observed using PETF sheet and aluminum foil as the packaging material. The resinification area increased with increasing temperature on the roll surface from 100 °C up to 150 °C under the condition of the water addition and rolling reduction ratio at 20 mass% and 70 %, respectively. The resinification area reached 90 % at more than 60 % of the rolling reduction ratio under the 20 mass% of water addition and 130 °C of the roll surface temperature. X-ray analysis showed that all the silk resin sheets consisted of silk II crystal structure. In addition, the broadening of FT-IR absorption peaks may be attributed to the formation of random-coil structure and Silk I. The bending strength of the silk resin sheet by the three-point bending test became lower with an increase in the rolling reduction ratio. The bending strength of the silk resin sheet exceeded 100 MPa at 40 % of the rolling reduction ratio, which was almost equivalent to that of the silk compact fabricated by pulse electric current sintering reported previously.