Study on the permeability of medical dialysis paper

Compared with non-woven fabric, medical dialysis paper has the characteristics of low price and easy to use. It can be heat sealed or glue sealed with PE, PP and other membrane materials, and is often used as the packaging material of medical devices in the medical packaging industry. At present, the domestic packaging materials are mainly ETO ethylene oxide method and high temperature wet steam method, so the medical dialysis paper is required to have a certain permeability, and has a small pore size, so as to block bacteria and dust, but allow ethylene oxide gas or steam through.

There are many factors that affect the permeability of paper, such as raw materials, beating process (such as beating concentration, beating power, beating degree, etc.), and papermaking process (such as pressing pressure, drying mode, pressing light, etc.). At the same time, the packaging of medical devices should also have the characteristics of complete sealing, protecting the contents of the package, fixing the contents of the package, anti-puncture and anti-friction, so the physical properties of medical dialysis paper such as tensile strength and break resistance should meet the requirements of ISO11607, EN868 series and GB19633 standards.

The beating degree and ratio of coniferous wood pulp and broadleaf wood pulp have important influence on the permeability of medical dialysis paper. Medical dialysis paper needs to meet many indicators such as: longitudinal tear ≥550mN, longitudinal tensile resistance > 4.40kN/m, transverse tensile resistance > 2.20kN/m, breathability > 3.4 mu m/Pa? s, aperture ≤50μm, medical device packaging when opened without paper hair. The large number of short fibers and small fibers will cause the uncleanly peeling of medical device packaging when opened. Therefore, it is necessary to control the dosage of broadleaf wood pulp in the process of copying, so as to improve the performance of the paper in all aspects.

PAE has an important influence on the permeability of medical dialysis paper. Some medical packaging needs to pass through high pressure steam before use, which requires medical dialysis paper to have a certain wet strength. Wet strength agent can be added in the production, and PAE is a widely used wet strength agent at present.

Dry strength agent has an important influence on the permeability of medical dialysis paper. The packaging of medical devices should have certain mechanical strength in the process of production, transportation and use. The commonly used dry strength agents are anion and cationic starch, cationic polyacrylamide, zwitterionic polyacrylamide or graft copolymer.

Sizing has an important effect on the permeability of medical dialysis paper. It is required that the packaging products have no paper hair when opened, and the peeling structure should be continuous and uniform, and do not pollute the medical devices after opening. Therefore, it is necessary to ensure moderate thermal sealing strength (0.80~8.00N/15mm), and further improve the internal binding strength and surface properties of medical dialysis paper. Surface sizing is one of the commonly used methods to improve surface properties.

The pressure gloss has an important effect on the permeability of medical dialysis paper. The equivalent pore size has a great influence on the bacteriological performance of medical packaging materials. ISO11607, EN868 series and GB19633 standards all propose that the average pore size of 10 pieces of paper is less than or equal to 35μm, and any piece should not be more than or equal to 50μm. Embossing can improve the surface properties of the paper, reduce the paper thickness, reduce the paper aperture, reduce the permeability of dialysis paper.

conclusion

Air permeability is an important index of medical dialysis paper, and it is necessary to have a certain air permeability in the process of medical device packaging. The experiment shows that the beating degree, ratio, wet strength agent, tensile strength agent and sizing agent of the slurry will affect the production of medical dialysis paper. Low needle and wide beating degree, high proportion of broadleaf wood pulp, appropriate sizing type and low pressure can improve the permeability of the paper. However, as medical dialysis paper is used as the packaging material of medical devices, its bacteriological resistance and mechanical properties are also important indicators, which need to be comprehensively considered in the actual production. When the beating degree of coniferous wood pulp is 22°SR, the beating degree of broadleaf wood pulp is 25°SR, the ratio of needle width to width is 75%:25%, the dosage of PAE is 1.0%, no tensile strength agent is added, and the sizing agent is 1:1 combination of PVA and cationic starch, ripening for 30min, and pressing light under 3kg/cm pressure, the prepared dialysis paper has good mechanical properties. The permeability of the paper is 5.1μm/Pa? s, equivalent aperture < 15 microns.