Silkworm cocoon waste revitalization: regenerated fibers using higher-molecular-weight fibroin achieve high strength and toughness

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K12305
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 64030:Environmental materials and recycle technology-related
• Research Institution: Shinshu University
• Principal Investigator: Yazawa Kenjiro 信州大学, 学術研究院繊維学系, 准教授 (70726596)
• Co-Investigator(Kenkyū-buntansha): 後藤 康夫 信州大学, 学術研究院繊維学系, 教授 (60262698)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: シルク / カイコ / 再生絹糸 / 溶液紡糸 / 野蚕 / クモ / 重鎖 / 軽鎖

Outline of Final Research Achievements

It is still difficult to produce silk artificially in a bulk-scale, and to develop recycling technology for silk is required. Solution spinning is one of the techniques for produce regenerated silk fibers. However, the problem is that the physical properties of the regenerated silk fibers are lower than those of natural silk fibers. In this study, we extracted the high molecular weight component, namely H chains, from silkworm silk fibroin and produced regenerated silk fibers consisting of H chains. We also produced regenerated silk fibers derived from wild silkworm fibroins. The obtained fibers presented the same strength as natural fibers, and the Young's modulus was 1.8 times higher, and the toughness was 1.2 times higher. Based on structural analysis, it was found that the silk molecular chains in the regenerated silk fibers were not completely oriented in the fiber axis direction even after post-stretching, and some crystals were aligned orthogonal to the fiber axis direction.

Free Research Field

タンパク質性繊維

Academic Significance and Societal Importance of the Research Achievements

生体由来の廃棄タンパク質から高機能な繊維を産み出す技術開発は、持続可能な開発目標の観点で重要である。カイコが産生する繭には、汚れや穴のある屑繭が一定量含まれる。また不要となった大量の絹の古着には、タンパク質原料としての活路が求められている。このような未利用絹は、精製してシルクフィブロインを回収した後、適当な溶媒に溶解し紡糸することで、再生絹糸として蘇らせることが可能である。しかし、再生繊維の力学物性は天然絹糸よりも劣ってしまう問題があった。本研究では、天然絹糸と同等の強度を持つ再生絹糸を創製し、タンパク質性繊維の工業的利用に貢献できると期待される。