JP2020044499A - Filter membrane and filtration method using the filter membrane - Google Patents

Abstract

To provide a filter membrane which has sufficient strength, has good wettability and prevents deformation and breakage even when a fragile and easy-to-deform component such as a blood cell and a gelatinous material is an object to be filtered, and has both high separation capability and high filtration speed.SOLUTION: The filter membrane has a plurality of through holes formed therein and selectively separates a specific material in a treatment medium from other material by using the through holes, in which the filter membrane is composed of a first layer having a first surface on a side to which the treatment medium is supplied and a second layer having a second surface on a side opposite to the first surface, the second layer has a large number of mutually parallel groove parts formed therein at a fixed interval, the first layer is thicker than the second layer, the first layer has a plurality of mutually isolated recesses formed, the recesses being formed of a curve which is larger than an interval of at least two neighboring groove parts and is closed in plan view, and, at portions where the groove parts and the recesses mutually overlap, there are through holes formed communicating the groove parts and the recesses.SELECTED DRAWING: Figure 1

Description

The present invention relates to a filter membrane and a filtration method using the filter membrane.

In recent years, with the rapid development of the economy, air pollution generated by people's economic activities has been gradually deteriorating, and in particular, air pollution has been caused by exhaust gas generated from automobiles and factories, which has a negative effect on human health. Is given. Therefore, various filters for removing pollutants from polluted air have been studied.

In addition, various studies have been made on filters for preventing viruses, bacteria, and the like contained in air that affect health from entering the human body. On the other hand, on the other hand, research is also being conducted on a filter that selectively filters only a specific component from constituent components of cells in a living body and obtains only the specific component.

As a filter capable of separating a specific component of such cells, Patent Document 1 discloses a membrane filter having a one-stroke structure in plan view, and Patent Document 2 discloses a membrane filter having a reinforcing portion. It has been disclosed.

In the above-mentioned filter, in order to realize a high aperture ratio, a reinforcing layer is not provided, or a reinforcing portion and a projection structure are combined to achieve both separation performance and membrane strength.

JP 2018-89592 A JP 2018-89593 A

However, in the membrane filters disclosed in Patent Documents 1 and 2 described above, there is a problem that the strength of the filter film is reduced in order to realize a filter having a sufficiently high aperture ratio.

The present invention has been made in view of the above-described problems, and has a sufficient strength, even when a brittle, easily deformable component such as blood cells or a gel-like component is to be filtered, An object of the present invention is to provide a filter membrane having good wettability, hardly causing deformation and tear, and having both high separation ability and high filtration speed, and a filtration method using the filter membrane.

The filter membrane of the present invention for solving the above-mentioned object is a filter membrane that selectively separates a specific material in a processing medium from other materials,
The filter membrane includes a first layer having a first surface that is a side to which the processing medium is supplied, and a second layer having a second surface opposite to the first surface.
In the second layer, a number of parallel grooves are formed at regular intervals.
The first layer is thicker than the second layer, and the first layer has a plurality of recesses which are at least larger than an interval between two adjacent grooves, have a closed curve in plan view, and are isolated from each other. ,
A through-hole communicating the groove and the recess is formed in a portion where the groove and the recess overlap each other.

In the filter membrane of the present invention, the first layer has a closed curve in plan view, and a plurality of recesses isolated from each other are formed. The wall of the recess is formed of a curved surface, and is larger than the object to be filtered. Therefore, the object to be filtered, which is a specific material in the target processing medium, is easily accommodated in the concave portion without being damaged, and the through-hole has an elongated shape due to the groove formed in the first layer. Therefore, even when a fragile and easily deformable substance such as a blood cell or gel is used as a filtration target, breakage or deformation hardly occurs, and filtration can be performed without damaging the filtration target. Therefore, for example, blood cell separation can be performed while suppressing hemolysis of red blood cells.

The through-hole has an elongated shape, and a groove is formed in the second layer, so that the object to be filtered that has passed through the through-hole formed in the concave portion of the first layer covers the entire area of the second layer. Easy to spread and good filtration efficiency.

Further, since the through-hole has an elongated shape, the aperture ratio can be increased, and a high separation capability and a high filtration speed can be realized.

Further, since the through-hole has an elongated shape, even if the through-hole is partially closed, it is difficult to completely close the through-hole, and the filtering ability can be maintained.

Further, since the thick first layer portion (rib portion) exists continuously over the entire filter film, it has high mechanical strength while having flexibility, has self-supporting properties, and has other properties. Even if the filter membrane is not supported by a support or the like, the shape can be maintained by the filter membrane alone, and the filter membrane does not cause irreversible aggregation in a lump. Further, the filter film can be prevented from being damaged due to a temperature change or a pressure during use of the filter due to the above characteristics.

The filter membrane of the present invention can be used as a filter membrane for removing clean air, gas, liquid, and the like by removing dust, viruses, bacteria, and the like present in air and gas and liquid of a specific component. Conversely, it can also be used as a filter membrane for selectively filtering and separating only particles of a specific size, viruses, bacteria, cells, etc. present in air or gas and liquid of a specific component. In particular, it can be suitably used as a filter membrane for separating solids such as cells and red blood cells from a body fluid.

In the filter membrane of the present invention, the shape of the concave portion formed in the first layer in a plan view is preferably a circle, an ellipse, or a racetrack shape.
In the filter membrane of the present invention, when the planar shape of the concave portion formed in the first layer is a circle, an ellipse, or a racetrack shape, the wall between the first surface and the bottom of the concave portion is formed. The portion is formed of a smooth curved surface, and even when red blood cells enter the recess, hemolysis or the like is less likely to occur.

In the filter membrane of the present invention, it is desirable that the shape of the groove in a plan view is a long and narrow rectangle having a predetermined width.
In the filter membrane of the present invention, when the shape of the groove in a plan view is an elongated rectangle having a predetermined width, the through-hole can be made elongated, and the various effects described above can be produced.

In the filter membrane of the present invention, it is desirable that the depth of the groove in the portion where the through hole communicating with the concave portion is not formed is deeper than the depth of the groove in the portion where the through hole communicating with the concave portion is formed. .
In the filter membrane of the present invention, if the depth of the groove in the portion where the through hole communicating with the concave portion is not formed is deeper than the depth of the groove in the portion where the through hole communicating with the concave portion is formed, The elasticity of the membrane is improved, and the filter membrane is less likely to be broken.

In the filter membrane of the present invention, it is preferable that the recess formed in the first layer has a through-hole communicating with three or more adjacent grooves.
In the filter membrane of the present invention, when the recess formed in the first layer is formed with through holes communicating with three or more grooves adjacent to each other, three or more through holes are formed in one recess. Since the holes are formed, the aperture ratio can be further increased, and a high separation capability and a high filtration rate can be realized.

In the filter membrane of the present invention, it is desirable that the filter membrane is made of the same material as a whole and is integrally formed.
When the filter membrane of the present invention is made of the same material as a whole and is integrally formed, layer separation occurs as in the case where a filter membrane is formed by bonding two layers, which has been conventionally performed. In addition, they have more excellent mechanical properties and are less likely to cause variations in pore area and pore diameter. Therefore, when used in applications such as inspections and experiments, data with good reproducibility can be obtained.

In the filter membrane of the present invention, the width of the groove is set so as to gradually decrease as it approaches the bottom of the groove from the second surface, and the recess is configured to approach the bottom of the recess from the first surface. It is desirable that the cross-sectional area parallel to the first surface be set so as to gradually decrease.
In the filter membrane of the present invention, the width of the groove is set to gradually decrease as approaching the bottom from the second surface, and the recess is parallel to the first surface as approaching the bottom from the first surface. If the cross-sectional area is set so as to become gradually smaller, the opening is less likely to be blocked by the non-filtration target substance, so that the filtration step can proceed efficiently and data with good reproducibility can be obtained.

In the shape of the cross section perpendicular to the second surface including the groove of the filter membrane of the present invention, the angle formed by the wall surface of the groove and the second surface is preferably 43 to 80 °.
In the shape of the cross section perpendicular to the second surface including the groove portion of the filter membrane of the present invention, when the angle between the wall surface of the groove portion and the second surface is 43 to 80 °, Since the area of the cross section parallel to the two surfaces is formed so as to become larger as approaching the second surface, the liquid contained in the object to be filtered is easily discharged, and the filtration step can proceed efficiently.

In the shape of the cross section perpendicular to the first surface including the concave portion of the filter membrane of the present invention, it is preferable that the angle formed by the wall surface of the concave portion and the first surface is 43 to 80 °.
In the shape of a cross section perpendicular to the first surface including the concave portion of the filter membrane of the present invention, when the angle between the wall surface of the concave portion and the first surface is 43 to 80 °, Since the area of the cross section parallel to one surface is formed so as to become larger as approaching the first surface, the filter membrane is less likely to be clogged with a substance not to be filtered, and the filtration is performed continuously for a long time. Thus, the filtration step can be efficiently completed.

In the filter membrane of the present invention, the width of the bottom of the groove is 0.1 to 2.0 μm, and the width of the second surface portion of the protrusion separating the two grooves is 0.5 to 5.0 μm. Desirably. More preferably, the width of the bottom of the groove is 0.3 to 0.7 μm, and the width of the second surface portion of the protrusion separating the two grooves is 1.0 to 3.0 μm.
In the filter membrane of the present invention, the width of the bottom of the groove is 0.1 to 2.0 μm, and the width of the second surface portion of the protrusion separating the two grooves is 0.5 to 5.0 μm. It is possible to remove dust, virus, etc. from gas containing very fine dust, virus, etc. Further, fine components in a liquid such as a cell can be selectively separated by filtration.

In the filter membrane of the present invention, the width of the longest portion at the bottom of the concave portion is preferably from 2.0 to 20.0 μm, more preferably from 5.0 to 10.0 μm.
In the filter membrane of the present invention, when the width of the longest portion at the bottom of the concave portion is 2.0 to 20.0 μm, it becomes possible to have a plurality of through holes inside the concave portion, and the aperture ratio is reduced. It can be set high, and high separation capacity and high filtration rate can be realized.

In the filter membrane of the present invention, the ratio of the total area (a ₁ ) of the portion corresponding to the first surface of the concave portion to the total area (A) of the filter membrane in a plan view is 10.0 to 50.0. %, More preferably 15.0 to 30.0%.
In the filter membrane of the present invention, the ratio of the total area (a ₁ ) of the portion corresponding to the first surface of the concave portion to the total area (A) of the filter membrane in a plan view is 10.0 to 50.0%. In this case, the area of the concave portion per unit area becomes sufficiently large, and the area of the portion where the filtration of the through hole is performed can be increased, so that the filtration can be performed efficiently.

In the filter membrane of the present invention, the total thickness of the first layer and the second layer is desirably 15 μm or less.
In the filter membrane of the present invention, when the total thickness of the first layer and the second layer is as thin as 15 μm or less, the object to be filtered easily passes, and the filtration can be performed efficiently and quickly.

The filtration method of the present invention is a filtration method using the filter membrane, wherein the treatment medium containing the specific component to be filtered first contacts the first surface of the filter membrane. It is characterized in that it is supplied to a filter membrane.

According to the filtration method of the present invention, the treatment medium containing the specific material to be filtered is supplied to the filter membrane such that the treatment medium first contacts the first surface of the filter membrane. The object to be filtered inside firstly has a closed curve in a plan view, is easily accommodated without damaging a concave portion larger than a plurality of objects to be filtered isolated from each other, and subsequently passes through an elongated through hole. As a result, even when a fragile, easily deformable substance such as a blood cell or gel is used as the filtration target, tearing or deformation hardly occurs, and the target specific component is not damaged. Can be filtered. Therefore, for example, blood cell separation can be performed while suppressing hemolysis of red blood cells.

In addition, since the through-hole has an elongated shape, the aperture ratio can be increased, and the filtration method of the present invention can achieve high separation capability and high filtration speed.

FIG. 1A is a plan view schematically showing an example of the filter film of the present invention, and FIG. 1B is a cross-sectional view of the filter film shown in FIG. FIG. 1C is a bottom view of the filter film shown in FIG. FIG. 2 is an enlarged cross-sectional view obtained by enlarging the cross-sectional view taken along the line AA shown in FIG. FIGS. 3A to 3C are cross-sectional views schematically showing a second-layer master mold manufacturing step in one example of the method for manufacturing a filter film of the present invention. FIGS. 4A to 4C are cross-sectional views schematically showing a second-layer master mold manufacturing process in another example of the method for manufacturing a filter film of the present invention. FIGS. 5A to 5D are cross-sectional views schematically showing a transfer mold manufacturing process in an example of the method for manufacturing a filter film of the present invention. FIGS. 6A to 6C are cross-sectional views schematically showing a first-layer mirror image mold manufacturing step and a photosensitive resin layer forming step of the present invention. FIGS. 7A to 7D are cross-sectional views schematically illustrating a groove forming step, a first-layer mirror image mold and a second-layer mirror image mold peeling step, and a residual film removing step.

(Detailed description of the invention)
Hereinafter, the filter membrane of the present invention will be described in detail.
The filter membrane of the present invention is a filter membrane for selectively separating a specific material in a processing medium from other materials, and the filter membrane has a first surface on which the processing medium is supplied. A first layer having a first surface and a second layer having a second surface opposite to the first surface. The second layer has a plurality of mutually parallel grooves formed at regular intervals. The first layer is thicker than the second layer, and the first layer has at least a distance between two adjacent groove portions, is formed of a closed curve in a plan view, and has a plurality of concave portions isolated from each other, A through-hole communicating the groove and the recess is formed in a portion where the groove and the recess overlap each other.

The filter membrane of the present invention can be used as a filter membrane for removing clean air, gas, liquid, and the like, by removing dust, viruses, bacteria, and the like present in air and gas and liquid of a specific component. Conversely, it can also be used as a filter membrane for selectively filtering and separating only cells such as particles of a specific size, viruses, bacteria, blood cells, etc. present in air or gas and liquid of a specific component. .

An example of the shape, structure, and the like of the above-described filter film of the present invention will be described in further detail.
FIG. 1A is a plan view schematically showing an example of the filter film of the present invention, and FIG. 1B is a cross-sectional view of the filter film shown in FIG. FIG. 1C is a bottom view of the filter film shown in FIG.

The filter membrane 10 of the present invention shown in FIGS. 1A to 1C includes a first layer 11 having a first surface 11a to which a processing medium is supplied, and a second layer 11 opposite to the first surface 11a. And a second layer 12 having a surface 12a. The second layer 12 has a large number of parallel grooves 12b formed at regular intervals. The first layer 11 is thicker than the second layer 12, the first layer 11 is formed with a plurality of recesses 11 b which are larger than the interval between two adjacent grooves 12 b, are circular in plan view, and are isolated from each other, In a portion where the groove portion 12b and the concave portion 11b overlap each other, a through hole 13 that connects the groove portion 12b and the concave portion 11b is formed.

As shown in FIGS. 1A to 1C, the filter membrane 10 of the present invention has a plurality of through-holes 13 communicating between the groove 12b and the recess 11b. It can be used as a filter membrane that selectively separates certain substances in the processing medium from other substances.

Although the filter film of the present invention can be conceptually divided into two layers, a first layer and a second layer, the filter film itself is made of the same material as a whole and is integrally formed. Is desirable.
If the filter film is made of the same material as a whole and is integrally formed, there is no possibility of causing a layer separation as in the case where the two layers are bonded, and it is more excellent in the mechanical properties and the two layers Are disadvantageous when stacking, that is, the variation in pore area and pore diameter hardly occurs. Therefore, when used in applications such as inspections and experiments, data with good reproducibility can be obtained.

Further, in the filter membrane of the present invention, the first layer is thicker than the second layer, the concave portion is present in isolation, and the first layer itself is continuous, and thus has autonomy. That is, since the portion including the continuous first layer having a large thickness exists over the entire filter membrane, it has high mechanical strength while having flexibility, has self-supporting properties, and has other supports and the like. Even if the filter membrane is not supported, the shape can be maintained with the filter membrane alone, and the filter membrane does not cause irreversible aggregation in a lump. Further, the filter film can be prevented from being damaged due to a temperature change or a pressure during use of the filter due to the above characteristics.

Further, the through-hole has an elongated shape, and a groove is formed in the second layer. Therefore, the object to be filtered that has passed through the through-hole formed in the concave portion of the first layer is formed in the second layer. Easy to spread over the whole area and good filtration efficiency.

Further, since the through-hole has an elongated shape, the aperture ratio can be increased, and a high separation capability and a high filtration speed can be realized.

Further, since the through-hole has an elongated shape, even if the through-hole is partially closed, it is difficult to completely close the through-hole, and the filtering ability can be maintained.

Examples of the resin material constituting the filter membrane of the present invention include a silicone resin, an acrylic resin, a polyimide resin, a phenol resin, and a silica hybrid composite. Since the resin has high flexibility, it has excellent mechanical properties, and it is easy to secure the self-sustainability of the filter membrane. In addition, at the time of filtration, a specific material to be filtered permeates a processed portion such as a groove and a through hole of the filter membrane by a capillary phenomenon. It is desirable to be hydrophilic. The method for manufacturing the filter membrane of the present invention will be described later in detail.
As a resin material constituting the filter membrane of the present invention, a negative silicone resin, an acrylic resin, a polyimide resin, a phenol resin, or the like can be used. When these resins are used, by irradiating light such as ultraviolet light, the irradiated part is cured, and the part not irradiated with ultraviolet light by a mask or the like has solubility in a solvent and is dissolved by a developer. , Can be removed.
As the resin material constituting the filter film of the present invention, a positive photosensitive resin may be used. Whether to use a negative resin or a positive photosensitive resin may be determined according to the accuracy of the filter film to be formed.

The silicone resin is a combination of tetrafunctional tetraalkoxysilane as a main component and trialkoxysilane, and finally, a three-dimensional structure of SiO is formed in the resin. Further, the silicone resin can be cured by using a catalyst or by heating. As described above, when the silicone resin is used as the resin film, the resin film has a three-dimensional structure of SiO, and thus is hard and has excellent wear resistance.

The acrylic resin is composed of a polyfunctional monomer / monofunctional monomer / polymer system, and the degree of crosslinking is controlled by the type and amount of the polyfunctional monomer. Examples of the polyfunctional monomer include polyol acrylate, polyester acrylate, urethane acrylate, epoxy acrylate, and the like. As described above, when an acrylic resin is used as the resin film, the resin film can be cured by ultraviolet rays in a short time.

The silica hybrid composite is a combination of inorganic fine particles such as silica sol or the above-described three-dimensional structure of SiO using a silicone resin and an acrylic resin or other resin used for forming a hard coat layer. By combining a resin having a radically polymerizable acryloyl group (AC), methacryloyl group (MAC), or cationically polymerizable oxetanyl group (OX), the resin can be cured by light such as ultraviolet light.

In the filter membrane of the present invention, the shape of the concave portion formed in the first layer as viewed in plan is preferably a circle, an ellipse, or a racetrack shape.
In the filter membrane of the present invention, when the planar shape of the concave portion formed in the first layer is a circle, an ellipse, or a racetrack shape, the wall between the first surface and the bottom of the concave portion is formed. The portion is formed of a smooth curved surface, and even when red blood cells enter the recess, hemolysis or the like is less likely to occur. It is more desirable that the shape of the concave portion in plan view be circular. This is because the concave portion can be easily formed.

In the filter membrane of the present invention, it is preferable that the recess formed in the first layer has a through-hole communicating with three or more adjacent grooves.
In the filter membrane of the present invention, when the recess formed in the first layer is formed with through holes communicating with three or more grooves adjacent to each other, three or more through holes are formed in one recess. Since the holes are formed, the aperture ratio can be further increased, and a high separation capability and a high filtration rate can be realized.

FIG. 2 is an enlarged cross-sectional view obtained by enlarging the cross-sectional view taken along the line AA shown in FIG.
As shown in FIG. 2, in the shape of the cross section perpendicular to the first surface 11 a including the concave portion 11 b of the filter membrane 10 of the present invention, the angle α between the wall surface 11 c of the concave portion 11 b and the first surface 11 a is 43 to Preferably, it is 80 °.
In the shape of the cross section perpendicular to the first surface 11a including the concave portion 11b of the filter membrane 10 of the present invention, if the angle α between the wall surface 11c of the concave portion 11b and the first surface 11a is 43 to 80 °, the concave portion 11b Since the area of the cross section parallel to the first surface 11a is formed so as to become larger as approaching the first surface 11a, the filter membrane is hardly clogged with the substance not to be filtered, and the filtration is performed continuously for a long time. The filtration step can be efficiently completed.

As shown in FIG. 2, the depth D2 of the groove 12b in the portion where the through hole 13 communicating with the recess 11b is not formed is equal to the depth of the groove 12b in the portion where the through hole 13 communicating with the recess 11b is formed. Is desirably deeper than the depth D1.
If the depth D2 of the groove 12b in the portion where the through hole 13 communicating with the recess 11b is not formed is deeper than the depth D1 of the groove 12b in the portion where the through hole 13 communicating with the recess 11b is formed, The elasticity of the filter film is improved, and the filter film is less likely to be broken.

In the filter membrane of the present invention, the width of the longest portion at the bottom of the concave portion is preferably from 2.0 to 20.0 μm, more preferably from 5.0 to 10.0 μm.
In the filter membrane of the present invention, when the width of the longest portion at the bottom of the concave portion is 2.0 to 20.0 μm, it becomes possible to have a plurality of through holes inside the concave portion, and the aperture ratio is reduced. It can be set high, and high separation capacity and high filtration rate can be realized.

In the filter membrane of the present invention, if the width of the longest portion at the bottom of the concave portion is less than 2.0 μm, it becomes difficult to have a plurality of through holes inside the concave portion, and the aperture ratio is set high. It becomes difficult. On the other hand, when the width of the longest portion at the bottom of the concave portion exceeds 20.0 μm, the ratio of the area of the thin portion increases, and the mechanical strength of the filter membrane becomes insufficient.

In the filter membrane of the present invention, the width of the groove is set so as to gradually decrease as it approaches the bottom of the groove from the second surface, and the recess is configured to approach the bottom of the recess from the first surface. It is desirable that the cross-sectional area parallel to the first surface be set so as to gradually decrease.
In the filter membrane of the present invention, the width of the groove is set to gradually decrease as approaching the bottom from the second surface, and the recess is parallel to the first surface as approaching the bottom from the first surface. If the cross-sectional area is set so as to become gradually smaller, the opening is less likely to be blocked by the non-filtration target substance, so that the filtration step can proceed efficiently and data with good reproducibility can be obtained.

As shown in FIG. 2, in the shape of a cross section perpendicular to the second surface 12 a including the groove 12 b of the filter membrane 10 of the present invention, the angle β formed between the wall surface 12 c of the groove 12 and the second surface 12 a is 43 to 43. Preferably, it is 80 °.
In the shape of the cross section perpendicular to the second surface 12a including the groove 12b of the filter membrane 10 of the present invention, if the angle β between the wall surface 12c of the groove 12 and the second surface 12a is 43 to 80 °, the groove 12b Since the area of the cross section parallel to the second surface 12a is formed so as to become larger as approaching the second surface 12a, the liquid contained in the object to be filtered is easily discharged, and the filtration step can be efficiently performed. it can.

In the filter membrane of the present invention, the ratio of the total area (a ₁ ) of the portion corresponding to the first surface of the concave portion to the total area (A) of the filter membrane in a plan view is 10.0 to 50.0. %, More preferably 15.0 to 30.0%.

In the filter membrane of the present invention, the ratio of the total area (a ₁ ) of the portion corresponding to the first surface of the concave portion to the total area (A) of the filter membrane in a plan view is 10.0 to 50.0%. In this case, the area of the concave portion per unit area becomes sufficiently large, and the area of the portion where the filtration of the through hole is performed can be increased, so that the filtration can be performed efficiently.

In the filter membrane of the present invention, the ratio of the total area (a ₁ ) of the portion corresponding to the first surface of the concave portion to the total area (A) of the filter membrane when viewed in a plan view is less than 10.0%. In addition, the area of the concave portion per unit area is too small, so that the area of the portion for filtering the through-hole cannot be made large, and it becomes difficult to perform the filtering efficiently. On the other hand, when the ratio of the total area (a ₁ ) of the portion corresponding to the first surface of the concave portion to the total area (A) of the filter film in a plan view exceeds 50.0%, The ratio of the area of the concave portion becomes too high, and the mechanical strength is reduced.

In the filter membrane of the present invention, it is desirable that the shape of the groove formed in the second layer is an elongated rectangle having a predetermined width.
In the filter membrane of the present invention, when the shape of the groove in a plan view is an elongated rectangle having a predetermined width, the through hole can be formed in an elongated shape, and various effects of the present invention can be produced.

In the filter membrane of the present invention, the groove is formed in a continuous shape, and the shape of the groove in plan view preferably has a one-stroke shape.
In the filter membrane of the present invention, the groove is formed in a continuous shape, and when the shape of the groove in a plan view has a single-stroke shape in a plan view, a convex portion formed between adjacent grooves is formed. Since the filter film is directed in various directions, the filter film has more excellent mechanical characteristics.

In the filter membrane of the present invention, the width of the bottom of the groove is 0.1 to 2.0 μm, and the width of the second surface portion of the protrusion separating the two grooves is 0.5 to 5.0 μm. Desirably. More preferably, the width of the bottom of the groove is 0.3 to 0.7 μm, and the width of the second surface portion of the protrusion separating the two grooves is 1.0 to 3.0 μm.
In the filter membrane of the present invention, the width of the bottom of the groove is 0.1 to 2.0 μm, and the width of the second surface portion of the protrusion separating the two grooves is 0.5 to 5.0 μm. It is possible to remove dust, virus, etc. from gas containing very fine dust, virus, etc. Further, fine components in a liquid such as a cell can be selectively separated by filtration.

In the filter membrane of the present invention, if the width of the bottom of the groove is less than 0.1 μm, the width of the through-hole is too narrow, and the filtration itself is possible, but the time required for the filtration is increased, and Not suitable for above. On the other hand, if the width of the bottom of the groove exceeds 2.0 μm, the width of the bottom of the groove is too wide, so that it becomes difficult to selectively separate cells and the like by filtration.

In the filter membrane of the present invention, when the width of the second surface portion of the projection separating the two grooves is less than 0.5 μm, the grooves are too close to each other, the width of the projection is reduced, and the strength of the filter membrane is reduced. Will decrease. On the other hand, if the width of the second surface portion of the protrusion that separates the two grooves exceeds 5.0 μm, the grooves are too far from each other, so that the density of through holes per unit area decreases and the filtration efficiency deteriorates.

In the filter membrane of the present invention, the total thickness of the first layer and the second layer is desirably 15 μm or less.
In the filter membrane of the present invention, when the total thickness of the first layer and the second layer is as thin as 15 μm or less, the object to be filtered easily passes, and the filtration can be performed efficiently and quickly.

Next, a filtration method using the filter membrane of the present invention will be described.
The filtration method of the present invention is a filtration method using the filter membrane, wherein the treatment medium containing the specific component to be filtered first contacts the first surface of the filter membrane. It is characterized in that it is supplied to a filter membrane.
Since the filter membrane used in the present invention has been sufficiently described, a detailed description thereof will be omitted here. However, as described above, when filtering, the specific material to be filtered is formed by the grooves of the filter membrane. The resin material forming the filter membrane is desirably hydrophilic because the processed part such as the through hole penetrates by capillary action.

According to the filtration method of the present invention, the treatment medium containing the specific material to be filtered is supplied to the filter membrane such that the treatment medium first contacts the first surface of the filter membrane. The object to be filtered inside firstly has a closed curve in a plan view, is easily accommodated without damaging a concave portion larger than a plurality of objects to be filtered isolated from each other, and subsequently passes through an elongated through hole. As a result, even when a fragile, easily deformable substance such as a blood cell or gel is used as the filtration target, tearing or deformation hardly occurs, and the target specific component is not damaged. Can be filtered. Therefore, for example, blood cell separation can be performed while suppressing hemolysis of red blood cells.

In addition, since the through-hole has an elongated shape, the aperture ratio can be increased, and the filtration method of the present invention can achieve high separation capability and high filtration speed.

Further, since the through-hole has an elongated shape, even if the through-hole is partially closed, it is difficult to completely close the through-hole, and the filtering ability can be maintained.

Next, a method for manufacturing a filter membrane of the present invention will be described.
The method for producing the filter membrane of the present invention is not particularly limited. For example, the filter membrane of the present invention can be formed by performing the following steps.

(1) First, as a second layer master mold manufacturing step, a second layer master mold having the same configuration as the second layer of the filter film of the present invention is manufactured to form a groove in the second layer.
(2) Next, as a transfer mold preparation step, a transparent thermoplastic resin film is heat-laminated on the second layer master mold prepared in the above step, and the irregular shape of the master mold is transferred and then peeled off. A transparent second layer mirror image mold is made.

(3) Next, as a first-layer mirror image mold manufacturing step, a first-layer mirror image mold having a shape in which the irregularities of the first layer are transferred onto a support plate made of Si or the like is manufactured.
(4) Next, as a photosensitive resin layer forming step, a coating liquid in which a negative photosensitive resin is dissolved in a solvent or the like is prepared, and the coating liquid is applied on the first layer mirror image mold and dried. The thickest portion becomes the thickness of the first layer and the second layer, and a photosensitive resin layer for a filter film having a concave portion is formed.

(5) Next, as the groove portion forming step, the second layer mirror image mold is pressed against the photosensitive resin layer for the filter film formed on the support plate, and then the photosensitive resin layer for the filter film is irradiated with ultraviolet rays. The layer is cured, and a groove having the same shape as the second layer is formed in the cured photosensitive resin layer for a filter film on the support plate.
(6) Next, as a first-layer mirror image mold and a second-layer mirror image mold peeling step, the second-layer mirror image mold is peeled from the cured photosensitive resin layer for the filter film in which the groove is formed. By peeling off the single-layer mirror image mold, a cured photosensitive resin layer for a filter film having a groove formed in the second layer and a recess formed in the first layer is produced.
(7) Lastly, as a residual film removing step, by irradiating the cured photosensitive resin for a filter film with an anisotropic plasma or the like, a portion where a groove portion and a concave portion where a very thin film remains is overlapped. Is removed, and the depth of the groove in the portion where the through hole communicating with the recess is not formed is made deeper than the depth of the groove in the portion where the through hole communicating with the recess is formed. .

The above steps (1) and (2) and the above steps (3) and (4) are steps that are not related to each other, and therefore either one may be the first. Further, the steps (1) and (2) and the steps (3) and (4) may be performed in parallel.

According to the above-described method for manufacturing a filter membrane of the present invention, a final filter membrane can be manufactured through the above-described steps, so that a filter membrane having a configuration such as a shape of an opening portion as designed can be manufactured with good reproducibility. can do.

Hereinafter, each step will be described in detail.
(1) Second-layer master mold manufacturing step In manufacturing the filter film of the present invention, the same as the second layer of the filter film of the present invention is performed as a master mold manufacturing step in order to form a groove in the second layer. The second layer master mold having the above structure is manufactured.

The method for producing the master mold is not particularly limited, but a method for producing a resin-made master mold on the base portion by using a photolithography and / or etching technique can be adopted.

FIGS. 3A to 3C are cross-sectional views schematically showing a second-layer master mold manufacturing step in one example of the method for manufacturing a filter film of the present invention. In the manufacturing method shown in FIGS. 3A to 3C, a master mold made of silicon or glass is manufactured.

In the second layer master mold manufacturing step, first, using a photolithography method, etching is performed so that the surface of the substrate 21 made of silicon or glass is exposed in plan view to expose the substrate surface 21a in the shape of a groove. A resist layer 25 is formed (see FIG. 3A).
The material of the glass is not particularly limited, and for example, general-purpose glass such as soda glass, and heat-resistant glass such as quartz glass and Tempax can be used.

Next, the base surface 21a is brought into contact with the etching gas for a predetermined time to form the groove 23 in the base 21 (see FIG. 3B). Next, the etching resist layer 25 is peeled off (see FIG. 3C), and the manufacturing process of the second layer master mold 20 in which the grooves 23 are formed in the base material 21 is completed.

Although silicon or glass is used in the second layer master mold manufacturing step, a resin master mold may be manufactured.
In this case, the resin that forms the master mold is not particularly limited, but the same resin material that forms the filter film of the present invention can be used. Examples of the resin material include a silicone resin, an acrylic resin, a phenol resin, a polyimide resin, and a silica hybrid composite. Since the resin has high flexibility, it has excellent mechanical properties, and is hardly worn even when the mirror image mold is manufactured many times.

These silicone-based resins, acrylic-based resins, phenolic resins, polyimide resins, and silica hybrid composites have been described in detail in the description of the resin material constituting the filter membrane of the present invention, and thus description thereof is omitted here. In the following processing, a negative photosensitive resin is used as the above resin, but a positive photosensitive resin may be used if necessary.

FIGS. 4A to 4C are cross-sectional views schematically showing a second-layer master mold manufacturing process in another example of the method for manufacturing a filter film of the present invention.
In this case, after preparing a coating solution in which the above resin is dissolved in a solvent or the like, the coating solution is applied on the base 36 and dried to form a coating layer 31 '(see FIG. 4A). . After the coating layer is dried and cured to form a cured resin layer 31, a glass plate patterned so as to expose a surface portion 31a corresponding to a portion other than the groove portion is provided as a mask 35 and irradiated with ultraviolet rays (FIG. 4). (B)). A lamp or the like is used as a light source for exposure.
The material of the base is not particularly limited, and examples thereof include thermosetting resins such as bismaleimide triazine resin, epoxy resin and silicone resin, metals such as silicon, and ceramics such as alumina and glass.

Next, the cured resin layer 31 is brought into contact with the developing solution for a predetermined time to dissolve and remove a groove portion other than the portion including the cured resin layer surface 31a to form a groove portion 33 (see FIG. 4C). Then, the manufacturing process of the second layer master mold 30 in which the groove 23 is formed in the cured resin layer 31 is completed.

(2) Transfer Mold Production Step FIGS. 5A to 5D are cross-sectional views schematically showing a transfer mold production step in an example of the method for producing a filter film of the present invention.
In the transfer mold manufacturing step of the present invention, the second layer master mold 20 (see FIG. 5 (a)) having the groove 23 formed in the second layer master mold manufacturing step shown in FIGS. Using a transparent thermoplastic resin film 41 ′ (see FIG. 5B), the thermoplastic resin film 41 ′ is thermally laminated to transfer the unevenness of the second layer master mold 20 (see FIG. 5C). ), And by peeling after cooling, a transparent second-layer mirror image mold 40 is produced (see FIG. 5D).

Examples of the material of the transparent thermoplastic resin film include cycloolefin polymer, polyvinyl chloride (PVC), polycarbonate (PC) resin, polyamide resin, acrylic resin such as polymethyl methacrylate resin, and polystyrene resin.
In the above process, the second layer mirror image mold 40 was produced by thermally laminating a transparent thermoplastic resin film 41 ′. However, a liquid resin is applied on the master mold 20 and cured by heating or the like. Then, by peeling off, a mirror image mold may be manufactured. According to this method, the second layer mirror image mold can be manufactured using a thermosetting resin such as a silicone resin.

The temperature of the heat lamination is preferably from 80 to 200C, and the time of the heat lamination is preferably from 0.5 to 5 minutes.

(3) First Layer Mirror Image Mold Manufacturing Step FIGS. 6A to 6C are cross-sectional views schematically showing the first layer mirror image mold manufacturing step and the photosensitive resin layer forming step of the present invention.
In the first-layer mirror image mold manufacturing process, a mask 55 is placed on the surface of the cured resin layer 51 formed on a support plate 56 made of silicon or the like, similarly to the method shown in FIGS. Irradiation of ultraviolet light onto the portion where the concave portion is to be formed by the transfer (see FIG. 6A), and then etching of the portion other than the above-described portion where the concave portion is formed, thereby transferring the unevenness of the first layer. The first-layer mirror image mold 50 made of resin described above is formed on the support plate 56 (see FIG. 6B).

In the method shown in FIGS. 6A and 6B, resin is used. However, as in the method shown in FIGS. 3A to 3C, selective etching or the like is performed using silicon. A first-layer mirror image mold having the shape shown in FIG.

(4) Photosensitive resin layer forming step In the photosensitive resin layer forming step, a coating liquid in which a negative photosensitive resin is dissolved in a solvent or the like is prepared, and the coating liquid is applied on the first layer mirror image mold 50. Then, the thickest portion becomes the thickness of the first layer and the second layer, and the photosensitive resin layer 61 ′ for the filter film having the concave portion is formed (see FIG. 6C).

(5) Groove forming step FIGS. 7A to 7D schematically show a groove forming step, a first-layer mirror image mold and a second-layer mirror image mold peeling step, and a residual film removing step. It is sectional drawing.
In the groove forming step, the second layer mirror image mold 40 produced in the transfer mold producing step is pressed against the photosensitive resin layer for the filter film formed on the support plate 56, and then the filter film is irradiated with ultraviolet rays. The photosensitive resin layer for curing is cured to form a cured photosensitive resin layer 61 for filter film having a groove 63 having the same shape as the second layer on the support plate 56 (see FIG. 7A).

(6) First Layer Mirror Image Mold and Second Layer Mirror Image Mold Peeling Step In the first layer mirror image mold and the second layer mirror image mold peeling step, the groove 63 is formed by peeling the second layer mirror image mold 40. The cured photosensitive resin layer 61 for a filter film is formed (see FIG. 7B). Further, by removing the first-layer mirror image mold 50, a groove 63 is formed in the second layer, and a concave portion is formed in the first layer. The cured photosensitive resin layer 61 for a filter film having the 61b formed thereon is formed (see FIG. 7C).

(7) Residual film removing step In the residual film removing step, an extremely thin film remains by irradiating the cured photosensitive resin for the filter film with anisotropic plasma or the like, so that the groove 63 and the recess 61b overlap. The removed portion is removed to form a through-hole 66, and the depth of the groove 63 in a portion where the through-hole 66 communicating with the recess 61b is not formed is formed with the through-hole 66 communicating with the recess 61b. The depth is greater than the depth of the groove 63 (see FIG. 7D), and the filter film 60 of the present invention is completed.

(Example)
Hereinafter, examples that more specifically disclose the present invention will be described. Note that the present invention is not limited to only these examples.

(Example 1)
(1) Second Layer Master Mold Production Step First, an etching resist layer is formed on the surface of the silicon base material 21 using a photolithography technique so that the base material surface 21a in the form of a groove is exposed when viewed in a plan view. 25 were formed (see FIG. 3A).

Next, the substrate surface 21a is brought into contact with an etching gas for a predetermined time to form a groove 23 in the substrate 21 (see FIG. 3B), and then the etching resist layer 25 is peeled off (FIG. c)), the second layer master mold 20 in which the groove 23 was formed in the base material 21 was produced.

(2) Transfer Mold Production Step In the transfer mold production step, a transparent heat made of a cycloolefin polymer is applied to the second layer master mold 20 (see FIG. 5A) produced in the second layer master mold production step. Using the thermoplastic resin film 41 ′ (see FIG. 5B), the thermoplastic resin film 41 ′ is thermally laminated to transfer the uneven shape of the second layer master mold (see FIG. 5C), and then peeled off. Thus, a second-layer mirror image mold 40 was produced (see FIG. 5D).

(3) First Layer Mirror Image Mold Production Step In the first layer mirror image mold production step, a coating solution obtained by dissolving a negative photosensitive polyimide resin in a solvent is applied onto a support plate 56 made of silicon or the like. A mask 55 made of a glass plate was placed on the surface of the cured resin layer 51 formed by curing, and a portion to be a concave portion was irradiated with ultraviolet rays (see FIG. 6A). Thereafter, the first layer mirror image mold 50 made of resin in which the irregularities of the first layer of the filter film of the present invention have been transferred is supported by contacting a developing solution and etching the portions other than the portions that become the concave portions. It was produced on a plate 56 (see FIG. 6B).

(4) Photosensitive Resin Layer Forming Step In the photosensitive resin layer forming step, a coating solution in which a negative photosensitive polyimide resin is dissolved in a solvent is prepared, and the coating solution is applied on the first layer mirror image mold 50. Then, a photosensitive resin layer 61 'for a filter film having a thickness to be a first layer and a second layer was formed (see FIG. 6C).

(5) Groove Forming Step In the groove forming step, the second layer mirror image mold 40 produced in the transfer mold producing step is pressed against the photosensitive resin layer for the filter film formed on the support plate 56, and then ultraviolet rays are applied. Irradiation cures the photosensitive resin layer for a filter film to form a cured photosensitive resin layer 61 for a filter film having a groove 63 having the same shape as the second layer on the support plate 56 (see FIG. 7A). .

(6) First Layer Mirror Image Mold and Second Layer Mirror Image Mold Peeling Step In the first layer mirror image mold and the second layer mirror image mold peeling step, the second layer mirror image mold 40 is peeled to have a groove 63. The cured photosensitive resin layer 61 for the filter film is formed (see FIG. 7B). Further, by removing the first layer mirror image mold 50, a groove 63 is formed in the second layer, and the concave portion 61b is formed in the first layer. Was formed as the cured photosensitive resin layer 61 for the filter film (see FIG. 7C).

(7) Residual film removing step Finally, as a residual film removing step, the anisotropic plasma is irradiated to the cured photosensitive resin for a filter film, so that a very thin film remains, and the groove 63 and the concave 61b are left. The overlapped portion is removed, a through hole 66 is formed, and the depth of the groove 63 in a portion where the through hole 66 communicating with the recess 61b is not formed is changed to a through hole 66 communicating with the recess 61b. The depth of the groove portion 63 is larger than the depth of the groove portion 63 (see FIG. 7D). The filter film 60 having the concave portion 61b in the first layer, the groove portion 63 in the second layer, and the through-hole 66 is provided. Was completed.
In the formed filter film, the width d of the through hole was 0.5 μm.

(Example 2)
(1) Second layer master mold preparation step After a negative photosensitive polyimide resin is dissolved in a solvent to prepare a coating solution, the coating solution is coated on a base portion 36 made of bismaleimide triazine resin, and dried. Then, a coating layer 31 'was formed (see FIG. 4A). After this coating layer was dried and cured to form a cured resin layer 31, a glass plate 35, which was patterned so that the surface portion 31a corresponding to the portion other than the groove portion was exposed, was set as a mask and irradiated with ultraviolet rays (FIG. 4). (B)).

Next, the cured resin layer 31 is brought into contact with the developing solution for a predetermined time to dissolve and remove a portion to be a groove other than a portion including the surface of the cured resin layer, thereby forming a groove 33 (see FIG. 4C). A second layer master mold 30 in which the groove 23 was formed in the cured resin layer 31 was produced.

Thereafter, in the same manner as in Example 1, (2) a transfer mold forming step, (3) a first-layer mirror image mold forming step, (4) a photosensitive resin layer forming step, (5) a groove forming step, (6) A first layer mirror image mold and second layer mirror image mold peeling step and (7) a residual film removing step are performed to form a groove 63 in the second layer, a recess 61b in the first layer, and a through hole. Thus, the filter membrane 60 of the present invention provided with the filter 66 was completed. Also in this filter film 60, the depth of the groove 63 in the portion where the through hole 66 communicating with the recess 61b is not formed is larger than the depth of the groove 63 in the portion where the through hole 66 communicating with the recess 61b is formed. It was deep.
In the formed filter film, the width d of the through hole was 0.5 μm.

Reference Signs List 10 filter film 11 first layer 11a first surface 11b, 61b recess 11c wall surface 12 second layer 12a second surface 12b groove 12c wall surface 13 through hole 20 second layer master mold 21 base material 21a base material surface 23, 33, 63 Groove portion 25 Etching resist layer 31 Hardened resin layer 31 'Coating layer 31a Surface portion 35 Mask 36 Base portion 40 Second layer mirror image mold 41' Thermoplastic resin film 50 First layer mirror image mold 55 Mask 56 Support plate 61 Filter film Cured photosensitive resin layer 61 'Photosensitive resin layer 66 for filter film Through hole

Claims (14)

A filter membrane that selectively separates a specific material in a processing medium from other materials,
The filter membrane includes a first layer having a first surface on a side to which the processing medium is supplied, and a second layer having a second surface opposite to the first surface,
A large number of parallel grooves are formed at regular intervals in the second layer,
The first layer is thicker than the second layer, and the first layer has a plurality of recesses which are at least larger than an interval between two adjacent grooves, have a closed curve in a plan view, and are isolated from each other. ,
A filter membrane, wherein a through-hole communicating the groove and the recess is formed in a portion where the groove and the recess overlap each other. The filter membrane according to claim 1, wherein a shape of the concave portion formed in the first layer in a plan view is a circle, an ellipse, or a racetrack shape. The filter membrane according to claim 1, wherein the shape of the groove in a plan view is an elongated rectangle having a predetermined width. 4. The groove according to claim 1, wherein a depth of the groove in a portion where the through hole communicating with the concave is not formed is greater than a depth of the groove in a portion where the through hole communicating with the concave is formed. 5. 3. The filter membrane according to item 1. The filter membrane according to any one of claims 1 to 4, wherein the recess formed in the first layer has a through-hole communicating with three or more grooves adjacent to each other. The filter membrane according to any one of claims 1 to 5, wherein the filter membrane is entirely made of the same material and is integrally formed. The groove is set so that its width gradually decreases as it approaches the bottom of the groove from the second surface, and the recess is parallel to the first surface as it approaches the bottom of the recess from the first surface. The filter membrane according to any one of claims 1 to 6, wherein the cross-sectional area is set to be gradually reduced. In the shape of a cross section perpendicular to the second surface including the groove,
The filter membrane according to any one of claims 1 to 7, wherein an angle between a wall surface of the groove and the second surface is 43 to 80 °. In the shape of a cross section perpendicular to the first surface including the recess,
The filter membrane according to any one of claims 1 to 8, wherein an angle between the wall surface of the concave portion and the first surface is 43 to 80 °. 10. The width of the bottom of the groove is 0.1 to 2.0 [mu] m, and the width of the second surface portion of the protrusion separating the two grooves is 0.5 to 5.0 [mu] m. A filter membrane according to any one of the preceding claims. The filter membrane according to any one of claims 1 to 10, wherein a width of a longest portion of a bottom of the concave portion is 2.0 to 20.0 µm. The filter membrane according to claim 1, wherein a total thickness of the first layer and the second layer is 15 μm or less. The ratio of the total area (a ₁ ) of the portion corresponding to the first surface of the concave portion to the total area (A) of the filter film when viewed in a plan view is 10.0 to 50.0%. 13. The filter membrane according to any one of 12 above. A filtration method using the filter membrane according to any one of claims 1 to 13,
A filtering method, comprising: supplying a processing medium to a filter membrane such that a processing medium containing a specific material to be filtered first contacts the first surface of the filter membrane.

Images