Development of a process for making thin-filament cellulosic fibers

Abstract

This articles examines the production of thin-filament cellulosic (viscose) filament fibers for making a filter-material that can efficiently remove leukocytes from blood and its components. The main requirements for the fibers were formulated on the basis of preliminary studies. Equipment was chosen, an existing AVK-0.6 unit was rebuilt, and a process was developed for producing the fibers. The process includes the stages of fiber formation, regeneration, and washing. Processes were also developed for forming tows from the filament fibers and cutting the tows into fibers 4-6 mm long. The fibers have been used to create a filter-material for filtering leukocytes from blood and its components.A process for making thin-filament cellulosic (viscose) fibers has been developed to create a Russian-made filtering material that can efficiently remove leukocytes from blood and other transfusion media.Leukocytes are known to be the principal means by which viral infections are transmitted. Agents that cause illness generally become attached to the cellular components of blood -leukocytes -or end up inside those components [1,2]. Providing patients with transfusions of leukocyte-free blood plasma, erythrocytes, or thrombocytes reduces the risk of infection by pathogens a hundred-fold.According to international requirements in the Guide to the Preparation, Use, and Quality Assurance of Blood Components (Council of Europe Press, 15th edition, 2009) and the Engineering Standard on the Safety Requirements for Blood and Its Products [3], the number of leukocytes remaining in a dose of any component of blood should not exceed 1·10 6 . Since some leukocytes have dimensions ≥ 7 μm -which is comparable to the 7-8 μm dimensions of erythrocytes -the problem of separating cells of nearly the same size in order to remove cells of one type (leukocytes) while allowing cells of another type (erythrocytes) to pass through the filter is very complex.After reviewing the patent literature, the best foreign-made blood-filtering materials, and the results of laboratory studies, we chose to a method of making filtering material that employs technology used in the production of paper. We also determined the main requirements for the fibrous components of the product. The most important requirements for the fibers used in the composition are that they be small in diameter, hydrophilic, and easily separated in an aqueous medium without forming floccules.An analysis of the properties of the chemical fibers produced in the nations of the CIS (Commonwealth of Independent States) during the period 2002-2007 showed that cellulose-hydrate fibers are the fibers best-suited for making filtering materials by the technology employed in paper production. These fibers have properties similar to those of natural cellulose fibers but absorb less water.In the process of formulating the technology, we came up with the following requirements for the cellulosehydrate fibers:-low linear density (no higher than 0.042 tex, which corresponds to a fiber diameter of 4.8 μm...