commonly referred to as "yellowing." Yellowing is one of the characteristics of aging a4 paper. (Five) a4 paper variant of. a4 paper produced in wet deformation and permanent deformation under wet and dry conditions. deformability a4 paper to print adversely. Generally, a4 paper deformation rate of the fiber and paper types and paper production related. Rag pulp grades deformation small, large chemical wood pulp paper create deformation unbleached chemical pulp is more easily deformed than bleached chemical pulp. Second, the aging of a4 paper archives in archives and use the process of gradually happening a4 paper archives irreversible change in appearance, structure and properties of the various aspects, known as "aging" or "deterioration." a4 paper aging concrete in three aspects, namely, color, strength decreases and changes chemical properties. 1. Item a4 paper acidic hydrolysis of cellulose. A4 paper archives departments at all levels of the majority of the existing archives containing acid. Acid is the most important factor causing the aging archives a4 paper even chalking. Because the archive acid catalyzed hydrolysis of cellulose degradation. Archive acid from: ① paper production process, such as mechanical papermaking cooking liquor, bleach, especially rosin sizing to a4 paper brought acid; ② acid gases in the air and dust in the acidic substances are Item adsorbed; ③ writing, printing on the archival a4 paper handwriting acid-containing material; ④ After Item mildew, fungi secrete organic acids, such as oxalic acid, citric acid; ⑤ cellulose, hemicellulose, especially wood Su produce acidic substances during oxidation or hydrolysis. 2. Item a4 paper enzymatic degradation of cellulose. When the records storage relative humidity, mildew on the archive easily. A4 paper archives after yellow mildew, stains little mechanical strength sharp decline in life seriously damaged archives. This metamorphism archives, mainly secreted by fungal cells in a variety of metabolic processes caused by enzymes, the most important is the cellulase. Cellulase is a specialized so-insoluble cellulose hydrolysis to biocatalyst soluble sugars. Cellulase violent catalysis can within three months of the a4 paper cellulose destroyed 10% to 60%. Experiments show that mildew after a4 paper archives firmness by 50% in five days, even if the long-term without turning i
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