JP4776986B2 - Sterilized filter media and sterile filter - Google Patents

Description

  The present invention relates to a sterilizing filter medium and a sterilizing filter including the sterilizing filter medium.

  Sterilization is a process for achieving sterility, that is, a process for killing or removing all microorganisms, and one of the sterilization methods is a filtration method. This filtration method is a method of removing microorganisms present in an object to be sterilized by filtration, and is applied to a gas or a liquid to which a heating method or an irradiation method cannot be applied. In this filtration method, membranes such as nitrocellulose, cellulose acetate, polyethersulfone, polysulfone, and polycarbonate have been used as filtration media (Non-patent Document 1). However, since these filter media are membranes, the filtration mechanism is surface filtration, so they are clogged immediately and have a short service life. In addition, these membranes are fragile, so they tend to break when processed into syringe filters, cartridge filters, etc., many membranes have problems with heat resistance, and there are cases where high-pressure steam sterilization (autoclave) may not be possible, Many membranes have problems with chemical resistance, and there is a problem that sterilized materials are limited (for example, nitrocellulose dissolves in alcohol).

“13th revised Japanese Pharmacopoeia Manual”, Yodogawa Shoten, 1996, p. B-885, p. B-890-892

  The present invention has been made in view of the above points. The first object of the present invention is to provide a sterilizing filter medium and a sterilizing filter which are not easily clogged and have a long service life. Another object is to provide a sterilizing filter medium and a sterilizing filter that are excellent in performance.

The invention according to claim 1 of the present invention, the average fiber diameter basis weight produced by 'electrostatic spinning is 5g / m ² ~35g / m ² is provided with the following ultrafine fibrous aggregate layer 170nm Sterile filter media characterized by. "

  The invention according to claim 2 of the present invention is "the sterile filter medium according to claim 1, wherein the average fiber diameter of the ultrafine fiber assembly layer is 150 nm or less."

  The invention according to claim 3 of the present invention is "the sterile filter medium according to claim 1 or 2, further comprising a non-ultrafine fiber assembly layer having an average fiber diameter exceeding 170 nm." is there.

  The invention according to claim 4 of the present invention is as follows: “The non-fine fiber aggregate layer is composed of a non-fine fiber aggregate layer produced by an electrospinning method”. . "

  The invention according to claim 5 of the present invention is "a sterilizing filter provided with the sterilizing filter medium according to any one of claims 1 to 4."

Since the sterilizing filter medium according to claim 1 of the present invention includes the ultrafine fiber assembly layer, the sterilized filter medium has a long service life because it can be filtered through the depth direction instead of surface filtration. The basis weight is 5g / m ² ~35g / m ² a is an average fiber diameter of 170nm or less of the ultrafine fibrous aggregate is filtered Brevundimonas.diminuta the smallest bacteria, it was confirmed that it is possible to substantially remove. Therefore, it can be used as a sterilizing filter material for objects to be sterilized in the food and beverage fields. In addition, it can be set as the sterilization filter material excellent in chemical resistance and heat resistance by selecting suitably the resin at the time of spinning an ultrafine fiber by the electrostatic spinning method.
Furthermore, since the fiber assembly layer is provided, there is flexibility, and damage is unlikely to occur when processing into a syringe filter or a cartridge filter.

  The sterilized filter medium according to claim 2 of the present invention is provided with an ultrafine fiber aggregate having an average fiber diameter of 150 nm or less, and the ultrafine fiber aggregate is filtered to completely remove Brerevundimonas.diminuta. did. Therefore, it can also be used as a sterile filter material for sterilized products in the pharmaceutical field.

  Since the sterile filter medium according to claim 3 of the present invention also includes a non-ultrafine fiber assembly layer having an average fiber diameter of more than 170 nm, clogging is less likely to occur and the service life is further increased.

  Since the sterile filter medium according to claim 4 of the present invention is composed of the non-fine fiber assembly layer produced by the electrostatic spinning method, by appropriately selecting a resin for spinning the non-fine fiber by the electrostatic spinning method. Since a non-fine fiber aggregate excellent in chemical resistance and heat resistance can be formed, it can be a sterile filter medium excellent in chemical resistance and heat resistance as a whole.

  Since the sterilization filter concerning Claim 5 of this invention is equipped with the said sterilization filter material, it is a sterilization filter which has a long use life, is hard to be damaged, and is excellent in heat resistance and chemical resistance.

  The sterilization in the sterile filter medium of the present invention means that the bacteria removal performance LRV described in the examples is 7 or more, and preferably 8 or more.

  In order to have such sterilization performance, the sterilizing filter medium of the present invention includes an ultrafine fiber aggregate layer having an average fiber diameter of 170 nm or less. The smaller the average fiber diameter of the ultrafine fiber assembly layer, the better the sterilization performance. Therefore, the average fiber diameter is more preferably 150 nm or less. In addition, although the minimum of an average fiber diameter is not specifically limited, When manufactured by the electrospinning method, generally 50 nm is a limit.

  “Fiber diameter” in the present invention means the diameter in the cross section of the fiber obtained by measuring from the electron micrograph of the cut surface in the thickness direction of the ultrafine fiber assembly layer, and the cross-sectional shape is non-circular The diameter of a circle having the same area as the cross section is regarded as the fiber diameter. The “average fiber diameter” refers to an arithmetic average value of fiber diameters of 50 or more fibers selected at random.

  The ultrafine fibers constituting the ultrafine fiber assembly layer of the present invention can be short fibers, but are preferably continuous fibers so that the ultrafine fibers are not easily dropped. In addition, when manufactured by the electrospinning method, it is generally a continuous fiber.

  The ultrafine fiber assembly layer of the present invention is produced by an electrospinning method. Therefore, by appropriately selecting a resin at the time of electrostatic spinning, a sterilizing filter medium having excellent heat resistance and excellent chemical resistance that is not affected by an object to be sterilized can be obtained. This electrostatic spinning method is a conventionally known method, and is a method of drawing and fiberizing by applying an electric field to a spinning solution supplied from a nozzle or the like.

  More specifically, first, a spinning solution is prepared. This spinning solution is a solution in which an ultrafine fiber constituent material is dissolved. For example, polyethylene glycol, partially saponified polyvinyl alcohol, fully saponified polyvinyl alcohol, polyvinyl pyrrolidone, polylactic acid, polyglycolic acid, polyacrylonitrile, polystyrene, polyamide, a solution in which an organic polymer such as polyolefin such as polyethylene or polypropylene is dissolved, or A spinnable sol solution obtained by hydrolyzing a metal alkoxide can be used. Spinning solutions in which materials other than those exemplified above are dissolved can also be used, and spinning solutions in which two or more kinds of materials including those other than those exemplified are dissolved can also be used.

  The solvent of the spinning solution varies depending on the ultrafine fiber constituent material and is not particularly limited. For example, water, acetone, methanol, ethanol, ethanol, propanol, isopropanol, toluene, benzene, cyclohexane, cyclohexanone, tetrahydrofuran, dimethyl sulfoxide, 1 , 4-dioxane, carbon tetrachloride, methylene chloride, chloroform, pyridine, trichloroethane, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, ethylene carbonate, diethyl carbonate, propylene carbonate, acetonitrile And so on. Solvents other than those exemplified above can also be used, and mixed solutions using two or more solvents including solvents other than those exemplified can also be used.

  Such a spinning solution is supplied to the nozzle and discharged from the nozzle, and an electric field is applied to the discharged spinning solution to form ultrafine fibers. The extrusion direction of the spinning solution is not particularly limited, but it is preferable that the discharge direction from the nozzle does not coincide with the action direction of gravity so that the spinning solution does not easily drop. In particular, it is preferable to discharge the spinning solution in a direction opposite to the direction of gravity or in a direction perpendicular to the direction of gravity.

  The diameter of the nozzle for discharging the spinning solution is preferably about 0.1 to 2 mm so that the average fiber diameter of the ultrafine fibers can be 170 nm or less.

  The nozzle may be made of metal or non-metal. If the nozzle is made of metal, the nozzle can be used as one electrode. If the nozzle is made of non-metal, an electric field is applied to the discharged spinning solution by installing an electrode inside the nozzle. Can do.

  After the spinning solution is discharged from such a nozzle, an electric field is applied to the discharged spinning solution to draw it into ultrafine fibers. This electric field varies depending on the average fiber diameter of the ultrafine fibers, the distance between the nozzle and the collector for collecting the ultrafine fibers, the solvent of the spinning solution, the viscosity of the spinning solution, and the like. In order to make an average fiber diameter 170 nm or less, it is preferable that it is 0.2-5 kV / cm. If the electric field to be applied is large, the average fiber diameter of the ultrafine fibers tends to decrease as the electric field value increases, but if it exceeds 5 kV / cm, air breakdown tends to occur, which is not preferable. Moreover, if it is less than 0.2 kV / cm, it is difficult to form a fiber shape.

  By applying an electric field to the spinning solution discharged as described above, an electrostatic charge is accumulated in the spinning solution, and is electrically pulled and stretched by an electrode (described later) on the collector side to form an ultrafine fiber. Since the fibers are electrically stretched, the speed of the fibers is accelerated by the electric field as the fibers approach the collector, resulting in ultrafine fibers having a smaller average fiber diameter. In addition, it is thought that it becomes thin by evaporation of the solvent, the electrostatic density is increased, it is split by the electric repulsive force, and it becomes an ultrafine fiber having a smaller average fiber diameter.

  Such an electric field is generated, for example, by providing a potential difference between the nozzle (the nozzle itself in the case of a metal nozzle, or the electrode inside the nozzle in the case of a non-metallic nozzle such as glass or resin) and the collector. , Can act. For example, a potential difference can be provided by applying a voltage to the nozzle and grounding the collector, and conversely, a potential difference can be provided by applying a voltage to the collector and grounding the nozzle. The apparatus for applying the voltage is not particularly limited, but a DC high voltage generator can be used, and a Van de Graf electromotive machine can also be used. The applied voltage is not particularly limited as long as the electric field intensity can be set as described above, but is preferably about 5 to 50 KV.

  Note that the polarity of the applied voltage may be either positive or negative. However, it is preferable to make the nozzle side have a positive potential so that the expansion of the ultrafine fibers can be suppressed, an ultrafine fiber assembly layer having a small pore diameter and a narrow pore diameter distribution can be formed. In particular, it is preferable that the counter electrode on the collector side is grounded, the nozzle side is applied positively, and the nozzle side has a positive potential so that corona discharge during voltage application can be easily suppressed.

  Subsequently, the ultrafine fibers that have been made into fibers can be accumulated on the collecting body to form an ultrafine fiber assembly layer. The collector is not particularly limited as long as it can collect ultrafine fibers, and is made of, for example, a conductive material such as metal or carbon, or a non-conductive material such as an organic polymer. Nonwoven fabric, woven fabric, knitted fabric, net, flat plate, drum, or belt can be used. In some cases, a liquid such as water or an organic solvent can be used as a collector.

As described above, when the collector is used as the other electrode, the collector is preferably made of a conductive material (for example, made of metal) having a volume resistance of 10 ⁹ Ω or less. On the other hand, when the conductive material is disposed as the counter electrode behind the collector as viewed from the nozzle side, the collector does not necessarily need to be a conductive material. As in the latter case, when the counter electrode is disposed behind the collector, the collector and the counter electrode may be in contact with each other or may be separated from each other.

Such ultrafine fibrous aggregate layer basis weight and thickness of not particularly limited, the basis weight is preferably from ^{5g / m 2 ~35g / m 2} , is 15g / ^{m 2} ~25g / m 2 Is more preferable. The thickness is preferably 50 μm to 500 μm, and more preferably 100 μm to 300 μm.

  The sterilizing filter medium of the present invention is provided with the above-described ultrafine fiber aggregate layer, but when further provided with a non-fine fiber aggregate layer having an average fiber diameter exceeding 170 nm, Since a certain amount of microorganisms can be filtered and removed by clogging, clogging is further less likely to occur, and the service life is further increased, which is a preferred embodiment.

  As described above, the non-fine fiber assembly layer has an average fiber diameter of preferably 200 nm to 800 nm, and more preferably 400 nm to 600 nm so that a certain amount of microorganisms can be filtered and removed.

  The non-fine fibers constituting the non-fine fiber assembly layer can be short fibers, but are preferably continuous fibers so that the non-fine fibers are not easily dropped.

  The non-fine fiber assembly layer is not particularly limited as long as it is composed of non-fine fibers having an average fiber diameter as described above. For example, the non-fine fiber aggregate layer is manufactured by an electrospinning method or manufactured by a melt blow method. And those obtained by gathering ultrafine fibers obtained by removing sea components of the sea-island type composite fibers. Among these, the non-fine fiber aggregate layer manufactured by the electrospinning method forms a non-fine fiber aggregate excellent in chemical resistance and heat resistance by appropriately selecting a resin in the same manner as the ultra-fine fiber aggregate layer. Therefore, the sterilizing filter medium having excellent chemical resistance and heat resistance as a whole can be obtained, which is preferable. The method for producing a non-fine fiber assembly by electrostatic spinning is basically the same as the method for producing an ultrafine fiber assembly. For example, by increasing the concentration of the spinning solution, the average fiber diameter is 170 nm. A non-fine fiber assembly exceeding 50 can be obtained.

Non ultrafine fibrous aggregate layer basis weight and thickness of the present invention is not particularly limited, the basis weight is preferably from ^{5g / m 2 ~35g / m 2} , at 15g / ^{m 2} ~25g / m 2 More preferably. The thickness is preferably 50 μm to 500 μm, and more preferably 100 μm to 300 μm.

  Further, when the non-fine fiber assembly layer is provided, the ultra-fine fiber assembly layer and the non-fine fiber assembly layer do not need to be one layer each, and one or both of the layers are two or more layers. There may be. In addition, the non-fine fiber assembly layer may or may not be bonded to the non-fine fiber assembly layer, but the non-fine fiber assembly layer and the ultra-fine fiber assembly layer are not separated. It is preferable that it is couple | bonded with. This is to prevent deterioration in processability when processing into a syringe filter or a cartridge filter. As a method for bonding the non-fine fiber assembly layer and the ultra-fine fiber assembly layer in this way, for example, a method of heating and pressurizing at a temperature at which the ultra-fine fiber and the non-fine fiber are not formed into a film can be exemplified.

Incidentally, if a ultrafine fibrous aggregate layer and the non-ultrafine fibrous aggregate layer is preferably the basis weight of the sterile filtered material is ^{10g / m 2 ~70g / m 2} , 20g / m 2 ~50g / m ² is more preferable. The thickness is preferably 100 μm to 700 μm, and more preferably 200 μm to 500 μm.

  Since the sterilizing filter of the present invention includes the sterilizing filter material as described above, it has a long service life and is excellent in heat resistance and chemical resistance. Further, since the sterilized filter medium is provided with the ultrafine fiber aggregate layer, it can be manufactured with good workability without being damaged at the time of filter processing as in a conventional membrane.

  The sterilization filter of the present invention can be, for example, a syringe filter or a cartridge filter. The former syringe filter is used for relatively small amount filtration, and the latter cartridge filter is used for large capacity filtration. More specifically, the syringe filter is formed by sandwiching the above-described sterile filter material having a disk shape with a diameter of 13 mm to 47 mm between a pair of top-shaped plastic moldings having grooves through which an object to be sterilized flows. It is a filter welded with a piece-shaped plastic molding. On the other hand, the cartridge filter may be a depth type in which the above-described sterile filter material is wound in multiple layers around the core material, or a pleat type in which the above-mentioned sterile filter material is wound in a zigzag shape around the core material. it can. In addition, a syringe filter is connected to a syringe or a tube, and a plunger of the syringe is pushed, or a tube is connected to a pump and used under pressure. The cartridge filter is used in a special container called a housing, and only the cartridge filter is replaced with an unused cartridge filter when the life is exhausted.

  Examples of the present invention will be described below, but the present invention is not limited to the following examples.

Example 1
(Formation of ultrafine fiber assembly layer)
A spinning solution having a concentration of 8 mass% in which polyacrylonitrile having a number average molecular weight of 150,000 was dissolved in dimethylformamide was prepared.

  Further, a polytetrafluoroethylene tube was connected to the syringe, and a stainless steel nozzle having an inner diameter of 0.6 mm was attached to the tip of the tube to obtain a spinning device. Next, a high voltage power source was connected to the nozzle. Furthermore, a drum (collector, grounding) having a stainless steel thin plate with conductive fluorine processing on the surface was installed at a position 10 cm away from the nozzle.

Next, the spinning solution is put into the syringe, and discharged using a microfeeder in a direction perpendicular to the acting direction of weight (discharge amount: 2.0 g / hour), and the drum is driven at a constant speed (surface speed: 0. 0). While rotating at 9 m / min), a voltage of +22 KV is applied to the nozzle from the high-voltage power source, and an electric field is applied to the discharged spinning solution to form ultrafine fibers, and continuous ultrafine fibers are formed on the stainless steel thin plate of the drum. By accumulating, an ultrafine fiber aggregate layer having an average fiber diameter of 160 nm, a basis weight of 21 g / m ² and a thickness of 127 μm was formed. The formation of the ultrafine fiber assembly layer, that is, electrostatic spinning was performed in an environment where the relative humidity of the spinning space was 30%. When forming the ultrafine fiber assembly layer, the nozzle is reciprocally swung at a constant speed (moving speed: 2.5 cm / min) in the direction perpendicular to the rotation direction of the drum to enhance the dispersibility of the ultrafine fibers. The uniformity of the ultrafine fiber assembly layer was improved. Thus, the ultrafine fibers were not in a bundled state, but the individual ultrafine fibers were uniformly dispersed.

(Formation of fine fiber assembly layer)
The use of a 16 mass% spinning solution in which polyacrylonitrile having a number average molecular weight of 500,000 was dissolved in dimethylformamide, the applied voltage from the high voltage power source to the nozzle was set to +16 KV, and the discharge amount from the nozzle was 2. A non-fine fiber aggregate layer having an average fiber diameter of 790 nm, a basis weight of 19 g / m ² , and a thickness of 131 μm was formed in the same manner as the ultrafine fiber aggregate layer except that the amount was 5 g / hour. The non-fine fibers were continuous fibers, and were not in a bundle state, but were in a state where the individual non-fine fibers were uniformly dispersed.

(Manufacture of sterile filter media)
After laminating the non-fine fiber assembly layer on the ultrafine fiber assembly layer, using a roller press machine (Asahi Textile Machine Industry Co., Ltd., JR-1000LTS), temperature 130 ° C., gauge pressure 4.9 kPa, The resultant was integrated by heating and pressing under conditions of 60 seconds to produce a sterile filter medium having a basis weight of 40 g / m ² and a thickness of 207 μm.

  Next, a syringe filter was produced using this sterile filter medium. This syringe filter can be manufactured without damaging the sterile filter medium, and the sterile filter medium has excellent processability.

(Example 2)
(Formation of ultrafine fiber assembly layer)
The preparation of a 6 mass% spinning solution in which polyacrylonitrile having a number average molecular weight of 500,000 was dissolved in dimethylformamide, the application voltage from the high voltage power source to the nozzle was set to +24 KV, and the discharge amount from the nozzle was 1. An ultrafine fiber assembly layer having an average fiber diameter of 130 nm, a basis weight of 16 g / m ² , and a thickness of 108 μm was formed in the same manner as in Example 1 except that the amount was changed to 5 g / hour. The ultrafine fibers were continuous fibers, and the ultrafine fibers were not in a bundle state, but the individual ultrafine fibers were in a uniformly dispersed state.

(Formation of non-fine fiber assembly layer)
A non-fine fiber aggregate layer having an average fiber diameter of 790 nm, a basis weight of 19 g / m ² , and a thickness of 131 μm was formed in exactly the same manner as the formation of the non-fine fiber aggregate layer of Example 1. The non-fine fibers were continuous fibers, and were not in a bundle state, but were in a state where the individual non-fine fibers were uniformly dispersed.

(Manufacture of sterile filter media)
In the same manner as in Example 1, a sterile filter medium having a basis weight of 35 g / m ² and a thickness of 213 μm was produced.

  Next, a syringe filter was produced using this sterile filter medium. This syringe filter can be manufactured without damaging the sterile filter medium, and the sterile filter medium has excellent processability.

(Example 3)
One ultrafine fiber assembly layer formed in exactly the same manner as in Example 1 was used as a sterile filter medium. Next, a syringe filter was produced using this sterile filter medium. This syringe filter can be manufactured without damaging the sterile filter medium, and the sterile filter medium has excellent processability.

Example 4
One ultrafine fiber assembly layer formed in exactly the same manner as in Example 2 was used as a sterile filter medium. Next, a syringe filter was produced using this sterile filter medium. This syringe filter can be manufactured without damaging the sterile filter medium, and the sterile filter medium has excellent processability.

(Comparative Example 1)
(Formation of non-fine fiber assembly layer A)
1. A 12 mass% spinning solution having polyacrylonitrile with a number average molecular weight of 500,000 dissolved in dimethylformamide was prepared, the applied voltage from the high voltage power source to the nozzle was set to +20 KV, and the discharge amount from the nozzle was 2. A non-fine fiber assembly layer A having an average fiber diameter of 210 nm, a basis weight of 20 g / m ² and a thickness of 117 μm was formed in the same manner as in Example 1 except that the amount was changed to 5 g / hour. The non-fine fibers were continuous fibers, and the non-fine fibers were not in a bundle state, but the individual non-fine fibers were in a uniformly dispersed state.

(Formation of non-fine fiber assembly layer B)
A non-fine fiber aggregate layer B having an average fiber diameter of 790 nm, a basis weight of 19 g / m ² , and a thickness of 131 μm was formed in exactly the same manner as the formation of the non-fine fiber aggregate layer of Example 1. The non-fine fibers were continuous fibers, and were not in a bundle state, but were in a state where the individual non-fine fibers were uniformly dispersed.

(Manufacture of filter media)
A filter medium having a basis weight of 38 g / m ² and a thickness of 214 μm was produced in exactly the same manner as in Example 1.

  Next, a syringe filter was manufactured using this filter medium.

(Comparative Example 2)
A commercially available syringe filter (manufactured by Sartorius Co., Ltd., “Minisart”, filter medium: cellulose acetate membrane, effective filtration area 5.3 cm ² , pore size 0.2 μm) was prepared.

(Bacteria removal performance)
According to JIS K3835-1990 "Testing method for bacteria capture performance of microfiltration membrane elements and modules", the bacteria removal performance of the syringe filters of Examples 1-4 and Comparative Examples 1-2 was examined. That is, the indicator bacterium Brevundimonas.diminuta was adjusted to a concentration of 4.91 × 10 ⁷ or more (the effective filtration area of the tested syringe filter was 4.91 cm ² , and the concentration per unit area was 10 ⁷ or more. The bacterial solution was pressure filtered at 100 KPa to obtain a filtrate until the syringe filter was clogged with bacteria and could not be filtered. The number of bacteria before and after filtration was measured, and the bacteria removal performance LRV was calculated from the following formula. The results are shown in Table 1.
LRV = log ₁₀ A / B (A: the number of bacteria before filtration, B: the number of bacteria after filtration, and when the number of bacteria after filtration is 0, 1 is used for B and is displayed as LRV ≧ log ₁₀ A / B)

(Filtration life)
The indicator bacterium Brevundimonas.diminuta was adjusted to a concentration of 10 ⁷ or more per 1 cm ² of the filter medium, the bacterial solution was filtered under pressure at 100 KPa, and the amount of filtration until the filter medium was clogged with bacteria and could not be filtered was measured. . The greater the amount of filtration, the longer the filtration life. The results are shown in Table 1.

As is clear from the results in Table 1, the filter media of the examples of the present invention were sterilizable with an LRV value of 7 or more. In addition, the filtration media of Examples 3 and 4 had a longer filtration life and a longer life than the conventional membrane, although the effective filtration area was smaller than that of the conventional membrane (Comparative Example 1). Furthermore, as is clear from the comparison between Examples 1 and 2 and Examples 3 and 4, the non-fine fiber assembly layer was provided, which resulted in a longer filtration life and a longer life. On the other hand, the filter material of Comparative Example 1 having an average fiber diameter exceeding 170 nm had an LRV value of 4.44 and was hardly able to filter Brerevundimonas.diminuta.

Claims (5)

Produced by electrostatic spinning, sterile filtering material, characterized in that the average fiber diameter basis weight is 5g / m ² ~35g / m ² is provided with the following ultrafine fibrous aggregate layer 170 nm. The sterilized filter medium according to claim 1, wherein an average fiber diameter of the ultrafine fiber aggregate layer is 150 nm or less. The sterile filter medium according to claim 1 or 2, further comprising a non-ultrafine fiber aggregate layer having an average fiber diameter exceeding 170 nm. The sterilizing filter medium according to claim 3, wherein the non-fine fiber assembly layer is a non-fine fiber assembly layer produced by an electrostatic spinning method. The sterilization filter provided with the sterilization filter material in any one of Claims 1-4.