A kind of bacterial cellulose dry film and its preparation method and application

Abstract

The invention provides a bacterial cellulose dry film as well as a preparation method and application thereof. The preparation method comprises the following steps of: pretreating a bacterial cellulose wet film; and performing gradient negative pressure heating molding to obtain the bacterial cellulose dry film. A gradient negative pressure is adopted to ensure that fibers cannot be flocculated, and the water in the wet film is removed as quickly as possible through heat transmission. The result shows that when the whole wet film is in a gradient negative pressure state, the atmospheric pressure on every part of the wet film is uniform and constant to provide a stable and uniform negative pressure environment for the wet film, and a continuous and stable heating temperature ensures rapid shaping of the wet film and the flatness and pressed density of the wet film after shaping. Due to a pumping action, the diffusion rate of the water in the wet film is increased, thereby promoting thermal circulation and greatly improving the heat treatment efficiency. The prepared dry film is good in uniformity and flatness, good in transparency, good in property of attaching to a skin when applied in the medical field, is stable in product quality, is easy to store, is light and thin, is convenient to pack and transport, and can be widely applied to various products with high added values.

Description

technical field [0001] The invention belongs to the field of cellulose dry film preparation, in particular to a bacterial cellulose dry film and its preparation method and application. Background technique [0002] Bacterial Cellulose (BC), a natural cellulose produced by microbial fermentation, has unique characteristics such as high purity, high Young's modulus, high crystallinity, strong water holding capacity, and good biocompatibility. Medical, food, textile, cosmetics, audio, papermaking, environmental protection, chemical industry, aerospace, national defense and other fields have a wide range of applications. Especially in the increasingly prominent contradiction between world population growth and limited arable land, as well as the increasing shortage of resources, bacterial cellulose, as a new type of biological material with a wide range of uses, has epoch-making significance and broad development prospects. [0003] The initial cellulose film produced by biolog...

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Problems solved by technology

[0004] The existing cellulose dry film preparation technology is still in the stage of laboratory exploration. There are three drying methods: heat drying, freeze drying, and vacuum drying, so as to dry the cellulose wet film into a dry film; High water content, sudden and rapid heat loss, uneven heating inside and outside the film, so the fiber flocculation is serious, the uniformity is poor, and the cellulose in contact with the heat source appears local paste and white circles; the edge of the film is curled and the surface is wrinkled

The method of vacuum drying has high equipment investment cost, slow dehydration rate, and serious loss of fine fibers. Generally, retention and drainage agents are added, which leads to high production costs, reduced purity of cellulose membrane, and cellulose’s unique natural network structure. Change; freeze-drying technology also has high equipment investment cost, the obtained dry film is too fluffy, the film surface flatness is poor, and the light transmittance of the product is low, so the application area is greatly limited. Combining the above-mentioned existing wet film drying methods, there are Due to many shortcomings such as high equipment investment, complex process, high production cost, and poor uniformity and permeability of the film, the preparation technology of cellulose dry film is the technical bottleneck of the large-scale and industrial promotion of cellulose. There is an urgent need for a simple and efficient , High-quality dry film production technology

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