| The sensitive film is an important carrier of art information and archives,which is extremely valuable in modern cultural heritage.The acetyl cellulose serving as film base has been widely used in the making of film in the 40s to the late 90s of the last century.They account for a considerable proportion in various types of image files.The hydrolysis of acetyl cellulose film base generating acetic acid syndrome has been found in 1985,and this phenomenon is widely popular in the world.After the acetic acid syndrome,the physical,chemical properties,and sound quality of film have been affected significantly.They mainly include that acetic acid gas releasing,surface crystal overlaying,film distortion,the image layer liquefying,the whole film bonding into blocks,the film acidification and severe embrittlement.The existence of these phenomena lead to the film beyond repair and digitization,as well as the rate of acetic acid syndrome cannot be slowed down.It has become a technical problem of archives industry security.The whole dissertation mainly includes the following five sections:1.In chapter one,the basic structure of sensitive film and its main diseases are introduced briefly.The forming reasons of acetic acid syndrome and it effect on the film is summarized.The domestic and foreign research progress on protection and restoration for acetate cellulose film that has occurred the acetic acid syndrome.The research background and content of this dissertation are listed.2.In chapter two,the mechanical strength,dimensional stability,pH,image layer surface morphology,hydrophilic,and glossiness change of acetate cellulose film base material are determined before and after acetic acid syndrome.The results show that the surface of film base releases plasticizer,acidity decrease,hydrophilic reinforcing,dimensional stability and mechanical strength severe drops after film cohere.The film does not engage with projector gear and leads to the unregularly screenings and digitization.The changes of structures and properties of acetate cellulose film before and after acidity cohere are investigated by using SEM,XRD,IR and TG technologies.The results show that the thermal stability and crystal integrity of base material are reduced,and the number of hydroxyl group is increased while the carbonyl group is decreased.This is because that the base of three acetate cellulose occurs through a deacetylation reaction,which leads to the arrangement of cellulose molecules becoming loose,and the intermolecular force becoming weaker.The problem of acidification and hardening of acetate cellulose film leads to the film not opening because of acetic acid syndrome.In this article,a new method of cohere film uncovering based on cryopreservation and gasification process of liquid nitrogen is studied.We also test the change of image layer and base material of cellulose acetate film before and after nondestructive uncovering.3.In chapter three,the problems of film serious acidification,body fragile,acetic acid syndrome acceleration,image layer deterioration leads to the unavailable and digitization of film.We develop a membrane deacidification method to protect the acetic acid syndrome film.The protection of acid acetic film by the way of film deacidification,the film appearance,surface drying time,hardness,adhesion and acidity serve as technical indicators to screen the film-forming and depickling materials,and to optimize the best ratio.The results show that the repairing solution is covered on the surface of the film,uniform particles,smooth,good light transmission the clear and complete image after the protection.The scanning effect of film is not affected after the restoration,and the original image of recorded film is restored.The tensile strength and folding endurance have different degrees of improvement after coating protective agent,which can effectively improve the mechanical strength of the original film,and increase the feasibility of screenings and digital scanning of acetate cellulose film.The contact angle between film emulsion layer and base layer is increased remarkably,the hydrophobicity of film is enhanced,and the hydrolysis of the base and image layer is suppressed after coating protective agent.The durability and acid fastness of the composite films are evaluated by using the XRD,IR,and TG technologies.It can be found that the surface morphology,hydrophilicity,glossiness,crystal structure,thermal stability,pH,dimensional stability and mechanical strength have minor change after aging,whereas the durability and acid fastness improve significantly after coating protective agent.4.In chapter four,the film bubble is generated between film base and emulsion layer,and its position without regularity.A part of bubbles grow on the image information and fill with plasticizer,which lead to serious cover of precious image information and develop an apparent form of film acetic acid syndrome.The questions about the film bubble diameter of 0.1?1 mm and its generated between film base and emulsion layer are difficult to repair by conventional methods.The micro repair,silver needle puncture,and optical filling are integrated to develop an effective method to repair the film bubble.The micron bubble repair system is used to locate the position of bubble accurately,and the plasticizer is cleaned in the bubble.In order to solve the problems such as the dilution and unclear of image data and handwriting after cleaning,we study the filling agent in the film bubble.The permeation time and filling liquid effect are selected as the main parameters to screen the kinds and concentrations of components in the process of filling.The results show that the high boiling point,nonvolatile liquid stabilizer phosphoric acid two benzyl isooctyl phosphite,sebacic acid ester and ethyl cellulose consist of the mixed solution can effectively remove the scattering interface of bubble inside.The original image information and handwriting are clearly displayed,so as to achieve better repair effect and better durability.5.In chapter five,the surface of 728 microfilms resulting from Republican period in the China Second Historical Archives cover large crystals and bubbles,which destroy image information seriously.Film base distortion,severe embrittlement,irrealizable use and digitization exist in the above microfilms,which belong to the performance of acetic acid syndrome.On the basis of the present situation and kinds of film diseases,we carried out the cleaning of the film surface,the distortion of the film body,the bubble repair of film emulsion layer surface,and the depickling reinforce of the film body,respectively.The restored film has clear image information,good mechanical performance,normal use and digitization,and the repaired film is stored in the durable collection box made by ourselves.Through experimental investigation on the diseases of film archives in the Guangxi Zhuang Autonomous Region Archives Bureau,it is found that the main occurrence of acetic acid syndrome is that they cause the whole film cohere,severe embrittlement,and irrealizable digitization.The nondestructive key technology of film cohere is adopted to take off adhesive film by liquid nitrogen.The restored film is further performed the deacidification and strengthening,and the repaired film is stored in the durable collection box made by ourselves.The 253 acetic acid syndrome color films resulting from Fujian Provincial Archives Bureau are uncovered,cleaned,shape restoration,deacidification and strengthening and durable collection... |
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