Medical dialysis paper must meet a number of criteria

Compared with non-woven fabrics, medical dialysis paper is cheaper and easier to use. It can be heat sealed or glue sealed with PE, PP and other membrane materials, and is often used as sterilization packaging materials for medical devices in the medical packaging industry. At present, the main sterilization methods for sterilization packaging materials in China are ETO ethylene oxide sterilization method and high temperature wet and hot steam method. Therefore, medical dialysis paper is required to have a certain air permeability, and a small pore size, so as to block bacteria and dust, but allows ethylene oxide gas or steam through.

There are many factors affecting the permeability of paper, such as raw materials, pulping process (such as pulping concentration, pulping power, pulping degree, etc.), paper making process such as pressing pressure, drying method, calenishing, etc. At the same time, the sterilization packaging of medical instruments should also have the characteristics of complete sealing, protecting the contents of the package, fixation of the contents of the package, anti-sting and anti-friction, etc. Therefore, the physical performance indexes of medical dialysis paper, such as tensile strength and burst resistance, should meet the requirements of ISO11607, EN868 series and GB19633.

The beating degree and ratio of conifer wood pulp and broadleaf wood pulp have an important effect on the air permeability of medical dialysis paper. Medical dialysis paper should meet many indicators such as: vertical and horizontal tearing degree ≥550mN, longitudinal tensile >4.40kN/m, transverse tensile >2.20kN/m, air permeability >3.4μm/Pa? S, Maximum pore size ≤50μm, Medical device sterilization package without paper hair when opened. The large number of short fibers and fine fibers will cause the unclean stripping when the sterilization packaging of medical instruments is opened, so it is necessary to control the dosage of broad-leaved wood pulp when making, so as to improve the performance of paper in all aspects.

PAE has an important effect on the breathability of medical dialysis paper. Some medical sterilization packages need to be sterilized by high-pressure steam before use, which requires medical dialysis paper to have a certain wet strength. Wet strength agent can be added in production, and PAE is the most widely used wet strength agent at present.

The dry strength agent has an important effect on the breathability of medical dialysis paper. Medical sterilization equipment packaging in the production, transportation and use of the process must have a certain strength of mechanical properties. The commonly used dry strength agent is mainly anion, cationic starch, cationic polyacrylamide, zwitterionic polyacrylamide or graft copolymer.

Sizing has an important effect on the breathability of medical dialysis paper. The sterilized packaging products are required to have no paper hair when opened, and the peeling structure should be continuous and uniform, and no contamination of medical devices after opening. Therefore, it is necessary to ensure moderate heat sealing strength (0.80~8.00N/15mm), and further improve the internal bonding strength and surface properties of medical dialysis paper. Surface sizing is one of the commonly used methods to improve the surface properties.

Polishing has an important effect on the breathability of medical dialysis paper. The maximum equivalent pore size has a great influence on the bacteriological performance of medical sterilized packaging materials. In ISO11607, EN868 series and GB19633 standards, it is proposed that the average pore size of 10 pieces of paper is less than or equal to 35μm, and any one piece should not be more than or equal to 50μm. Calendering can improve the surface properties of the paper, reduce the thickness of the paper, reduce the pore size of the paper, and reduce the permeability of dialysis paper.

conclusion

The air permeability is an important index of medical dialysis paper, and the sterilization package of medical equipment needs to have certain air permeability during the sterilization process.the experiment shows that in the production process of medical dialysis paper, the pulping degree, ratio, wet strength agent, tensile strength agent and sizing agent all have an effect. Low needle and width beating degree, higher ratio of broad-leaved wood pulp, appropriate sizing type and lower pressure-pressure can improve the air permeability of paper. However, as medical dialysis paper is used as the packaging material of medical instruments, its bacteria-resistance and mechanical properties are also important indicators, which should be comprehensively considered in the actual production. When the beating degree of coniferous wood pulp is 22°SR, the beating degree of broad-leaved wood pulp is 25°SR, the ratio of needle width is 75%:25%, the dosage of PAE is 1.0%, no tensile strength agent is added, and the sizing agent is 1:1 mixture of PVA and cationic starch, the aging time is 30min, and the pressure of 3kg/cm is pressed, the dialysis paper prepared has good mechanical properties. The permeability of the paper is 5.1μm/Pa? S, the maximum equivalent pore diameter <15μm.