Quantitative deterioration diagnosis of the motion-picture film by NMR spectroscopy

西谷, 拓哉, 城所, 学, 矢島, 仁, 高橋, 圭子, Nishitani, Takuya, Kidokoro, Gaku, Yajima, Hitoshi, Takahashi, Keiko

アセチルセルロースをモデル物質の逐次アセチル置換基数に対応するグルコース基由来、アセチル基由来プロトンの理論個数を算出し、平均置換度 DS との相関をグラフ化して検量線を作成した。重合度 100 のセルロースモデル物質の相関曲線でも置換度検量線として用いることが出来る事が判明した。非フィルム試料 TAC、ACl の NMR スペクトル測定結果および溶媒試験により被験フィルム 3 mg をDMSO-d6に溶解させ、60℃で、グルコース基由来シグナル範囲(5.6～2.8 ppm)とアセチル基由来シグナル範囲(2.2～1.7 ppm)の積分比を検量線にてDSを算出すると平均アセチル化度が算出でき、劣化早期診断が出来る事が判明した。さらにフィルム可塑剤も同時に定性定量可能である。本研究では到達出来なかったが、復元の予備データとしても有用である。以上 NMR によりビネガーシンドロームの定量的診断法を確立した。

Vinegar syndrome is a term used to describe the chemical phenomenon that occurs during the deterioration of cellulose acetate (CA) base motion-picture film, the symptoms of which are a vinegar odor, film shrinkage, embrittlement, buckling of the gelatin emulsion, and the formation of a white precipitate on the film surface. Cellulose triacetate (TAC), which contains no free hydroxyl groups (DS = 3.0) is a typical CA derivative and is used as the base material for photographic films, motionpicture films, and microfilms since the 1920s as a replacement for the unstable and highly flammable cellulose nitrate base film. Although standard storage conditions for TAC base films have been established over recent decades, chemical analysis of the degradation products have not been clarified, and no specific diagnostic technique has been developed. We focused on the complete chemical analysis of the films. We attempted to identify the additives and the structure of films based on results from nuclear magnetic resonance (NMR) spectroscopy. The average of degree of substitution (DS) can be decided using only 3 mg of film using NMR method under high temperature in dimethyl sulfoxide solution.

Quantitative deterioration diagnosis of the motion-picture film by NMR spectroscopy

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