JPH0443690B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a medical hollow fiber membrane. Porous hollow fiber membranes made of high molecular weight polymers have selective permeation performance, and are used in a variety of applications by taking advantage of this property. A wide variety of hollow fiber membranes are available by changing the raw material composition, method of forming the hollow fiber membrane, post-treatment method, etc. under conditions depending on the purpose of use. Among these, there has been a remarkable expansion into the medical field, and the production of hollow fiber membranes for artificial dialysis is steadily increasing, partly because there are many patients with renal diseases who need them.
On the other hand, hollow fiber membranes intended for the medical field must be given sufficient consideration in terms of health and safety from manufacture to delivery to users. Specially used as a cleaning agent in hollow fiber membrane manufacturing methods, in which a polymer compound is dissolved in a solvent to form a spinning dope, this spinning dope is extruded together with a core solution from a spinning nozzle, coagulated, and then washed to remove the solvent. In some cases, chemicals or water containing impurities are used, but in these cases, the chemicals and impurities remain in the hollow fiber membrane, making it extremely unsuitable for use as a medical hollow fiber membrane. Furthermore, the use of water containing bacteria is also undesirable as it results in bacteria adhering to the hollow fiber membrane. Bacteria are usually present everywhere and can easily be introduced into the hollow fiber membrane manufacturing process with the slightest carelessness, and the average generation time of bacteria varies depending on the type, but ranges from several tens of minutes to several hours. This means that once contaminated, bacteria can easily multiply.
The manufacturing of medical devices is normally carried out in clean rooms, but even so, we cannot be optimistic. Usually, medical hollow fibers are made into modules and undergo a sterilization process to increase safety before being delivered to the user. If the hollow fibers contain bacteria before the module is made, viable bacteria can be eliminated in the sterilization process, but there is a risk that they may still contain, for example, virogien (a pyrogenic substance). The inventors of the present invention have discovered the present invention as a result of intensive studies on means for obtaining medical hollow fiber membranes that are free from adhesion of bacteria. That is, the present invention provides a method for manufacturing hollow fiber membranes for medical use, in which a polymer compound is dissolved in a solvent to form a spinning dope, and this spinning dope is extruded from a spinning nozzle together with a core solution, coagulated, and then washed to remove the solvent from the spinning dope. This method is characterized in that the washing process is divided into multiple stages, and sterile water is used as the washing water, and the washing water is made to flow in a direction opposite to the direction in which the hollow fiber membrane runs. The sterile water used in the present invention is water that has been tested and passed by the membrane filter method of the sterility test method of the Japanese Pharmacopoeia. The polymer compounds used in the present invention are not particularly limited, and include cellulose esters such as cellulose diacetate and cellulose triacetate; cuprammonium cellulose; polyacrylonitrile; polymethyl methacrylate; polyethylene; and vinyl acetate copolymer. ; polyvinyl alcohol; polypropylene and the like. These polymer compounds are dissolved in a suitable solvent to prepare a spinning stock solution. Then, this spinning dope is spun out from an annular spinning hole, passed through the air as required, and then solidified. The coagulated hollow fiber is then washed to remove the solvent and produce a medical hollow fiber membrane. An important point in the present invention is that sterile water is used as the washing water during such washing. By employing such a method, a hollow fiber membrane containing no bacteria could be produced. This washing step may be carried out in a single bath or in a bath divided into multiple stages, but preferably a multi-stage divided method (several stages to more than ten stages) is preferred because it increases the cleaning efficiency. In this multistage division, fresh sterile water flows down into each independent bath to treat the hollow fiber membranes. In addition, it is preferable to provide an ultraviolet sterilizing lamp in the cleaning process in order to prevent the proliferation of viable bacteria that may have been contaminated. Such washing water is caused to flow down in the direction opposite to the direction in which the hollow fiber membrane runs. In this way, when producing medical hollow fiber membranes, by using sterile water as the washing water, hollow fiber membranes with sufficient consideration given to the safety and hygiene aspects of sterile conditions can be created, which can greatly contribute to the medical field. . Examples of the present invention will be described below, but the present invention is not limited in any way by these Examples. Examples 1 to 3 and Comparative Examples 1 to 2 30 parts by weight of cellulose acetate, 49 parts by weight of dimethylformamide, 200 parts by weight of polyethylene glycol
A spinning stock solution was prepared by stirring and dissolving 21 parts by weight at 85° C. for 2 hours. This spinning stock solution was left standing at 85° C. for 2 hours to defoam. Spinning was carried out using an annular orifice nozzle. On the other hand, liquid paraffin was supplied as a core liquid. The hollow stock solution exiting the annular orifice is
cm in air, then introduced into a coagulation bath to coagulate, and then rinsed with water. For this cleaning, follow the 3 steps below.
Sterile water was adjusted each time on the street and flowed down in the opposite direction to the direction of travel of the hollow fiber membrane. After that, it was wound into a bobbin shape. Example 1 The canal for the cleaning process was divided into three sections and sterile water was introduced at the end of each section. Example 2 The canals of each of the three stages of the multi-stage canal were made independent, and sterile water was introduced into the rearmost part of each canal. Example 3 Same as Example 2, but each canal was further irradiated with an ultraviolet germicidal lamp. For comparison, we also considered an example in which ion-exchanged water was used instead of sterile water. Comparative Example 1 Same as Example 1, but using ion exchange water instead of sterile water. Comparative Example 2 Same as Example 2, but using ion exchange water instead of sterile water. The results of the above Examples and Comparative Examples over time are summarized in Table 1.

【table】

【table】

[Table] From the above results, it can be seen that when producing medical hollow fiber membranes, if sterile water is used as the washing water, hollow fiber membranes suitable for medical use without any retention state can be produced.

Claims (1)

[Claims] 1. In a medical hollow fiber membrane manufacturing method in which a polymer compound is dissolved in a solvent to obtain a spinning solution, this spinning solution is extruded from a spinning nozzle together with a core liquid, solidified, and then washed to remove the solvent from the spinning solution. A method for manufacturing a medical hollow fiber membrane, characterized in that the process is divided into multiple stages, and sterile water is used as the washing water, and the water is allowed to flow down in a direction opposite to the direction in which the hollow fiber membrane runs.