JP5926696B2 - Method for producing porous film - Google Patents

Description

The present invention relates to a manufacturing method of porous fill-time.

  Various uses such as cell culture substrates, wound dressings, adhesion-preventing membranes, and hemostatic agents have been studied for porous films made from hydrophobic polymers. These studies focus on the fact that the fine structure of the porous film has effects such as improvement of cell culture efficiency and adhesion to living bodies. In such an application, a film surface (hereinafter referred to as a porous surface) on which a large number of pores of the porous film are formed may be brought into contact with cells collected from a living body, or the porous surface may be brought into contact with the inside or outside of the body. Assumed.

  A porous film as an adhesion preventing film is disclosed as a biodegradable film having a honeycomb structure of Patent Document 1, for example. For example, Patent Document 2 proposes a porous anti-adhesive agent composed of a copolymer of lactic acid and caprolactone.

International Publication No. 2004/088944 JP 2000-197693 A

  However, when a porous film is used as a cell culture substrate, cell culture efficiency may decrease. In addition, when the porous film is adhered inside or outside the living body, inflammation may occur at the adhered site.

The present invention does not reduce the culture efficiency of the cell, and an object thereof is to provide a manufacturing method of inhibiting inflammation porous fill beam in the adhesive part of the living body.

  In the method for producing a porous film of the present invention, a casting film forming step of casting a solution in which a hydrophobic polymer is dissolved in a solvent to form a casting film, and a plurality of holes are formed on one film surface. A film forming process for forming a porous film from a cast film, and a low molecular weight material in the porous film by removing a low molecular weight material having a molecular weight of 500 or less from at least one of a hydrophobic polymer, a cast film, and a porous film. And a removal step of suppressing the content of the slag to 5% by mass or less.

  The removing step is preferably a step of immersing the porous film in at least one of water and alcohol.

  The porous film is formed with a plurality of holes arranged side by side along one film surface, and has a honeycomb structure when the film surface is viewed from the vertical direction. It is preferable to have a step of forming water droplets, and an evaporation step of forming a porous film by evaporating the solvent and water droplets from the cast film.

According to the manufacturing method of the present onset Ming porous film, without reducing the culture efficiency of the cell, it is possible to produce a porous film having inflammation in the adhesive part of the living body is suppressed.

It is a top view of a porous film. It is sectional drawing which follows the II-II line of FIG. It is sectional drawing which follows the III-III line of FIG. It is a manufacturing process of a porous film. It is explanatory drawing of how to obtain | require the content rate of the low molecular weight substance by GPC. It is a manufacturing process of a porous film. It is a top view of a porous film. It is sectional drawing which follows the VV line of FIG. It is a manufacturing process of a porous film. It is a microscope picture of the obtained porous film. It is a graph of the molecular weight distribution of the porous film manufactured in the Example. It is a microscope picture of the obtained porous film. It is a graph of the molecular weight distribution of the porous film manufactured by the comparative example.

As shown in FIGS. 1 to 3, the porous film (hereinafter referred to as a film) 10 has a plurality of holes 11 arranged side by side along one film surface 10 a, and the film is viewed from the direction perpendicular to the film surface 10 a. When 10 is seen, it has a honeycomb structure. With the honeycomb structure, the shape of the opening of the hole 11 when the film 10 is viewed from the film surface 10a does not have to be strictly a hexagon, and may be a circle as shown in FIG. In addition, the shape of the opening of the hole 11 may be, for example, a rounded substantially hexagonal shape or a substantially octagonal shape depending on the density of the holes per unit area of the film surface 10a or the distance between adjacent holes. The honeycomb structure includes such an embodiment.

  In the film 10 shown in FIG.2 and FIG.3, each hole 11 is formed as a hollow in one film surface 10a, and does not penetrate in the thickness direction. However, the present invention is not limited to this aspect. For example, each hole 11 may be formed penetrating in the thickness direction from one film surface 10a to the other film surface 10b.

  In the film 10 shown in FIG.2 and FIG.3, the partition 13 exists between the adjacent hole 11 and the hole 11, and each hole 11 is independent. However, depending on the size, density, and the like when water droplets are formed in the casting film by the dew condensation method as described below, there is no partition wall 13 and a communication path along the film surface may be formed inside the film. is there.

  With the structure in which a plurality of holes 11 are formed along one film surface 10a as described above, the film 10 adheres to a predetermined part of a cell or a living body. This adhesive action is due to the retention of cells and biological water in the holes 11 by capillary force.

  The diameter D of the hole 11 is preferably in the range of 100 nm to 20 μm. Thereby, adhesion to a cell or a living body becomes more reliable. Therefore, the film 10 stays more reliably at a predetermined site to be adhered, and the cells to be cultured survive and proliferate without being detached from the film 10. The diameter D is preferably in the range of 300 nm to 10 μm from the viewpoint of adhesive strength. More desirably, it is in the range of 500 nm to 5 μm. When the film 10 is made of a biodegradable polymer, the film 10 stays more securely at a predetermined site to be bonded for a certain period of time.

  The thickness T10 of the film 10 is generally in the range of 0.5 μm to 30 μm. Further, the depth L10 of the hole 11 is generally in the range of 0.3 μm to 20 μm.

  The film 10 is composed of a hydrophobic polymer. As the hydrophobic polymer, polylactic acid, polycaprolactone, polyglycolic acid, polydioxanone, polyhydroxybutyrate, polybutadiene, polyurethane, polystyrene, polymethyl methacrylate, and a copolymer containing these are preferable.

  Many polymers include monomers that have a molecular weight distribution and that were not polymerized when produced, and oligomers that did not have a high degree of polymerization. In addition, other components used in the reaction to be generated and impurities may be mixed. The film 10 has a content of a low molecular weight substance (hereinafter referred to as a low molecular weight substance) having a molecular weight of more than 0 and 500 or less, and is suppressed to 5% by mass at most. That is, in the film 10, when the mass of the film 10 is X (g) and the mass of the low molecular weight substance is Y (g), the value obtained by (Y / X) × 100 is 5 or less. Thereby, even if the film 10 adhere | attaches on a biological body, the inflammation of the predetermined site | part (henceforth an adhesion site | part) of the adhere | attached biological body is suppressed. Further, even when the film 10 is used as a base material for culturing cells, the cell culture is not inhibited and the culture efficiency does not decrease.

  A living body contains water, and when a cell and a film are brought into contact with each other or when a film is stuck inside or outside the living body, the film comes into contact with water. In addition, a porous film having a large number of holes has a very large specific surface area compared to a so-called flat film in which the holes 11 are not formed and both film surfaces are flat. For this reason, when a conventional porous film is brought into contact with cells or inside or outside a living body, a low molecular substance that is easily dissolved in water is more easily dissolved than a flat film, and the dissolved low molecular substance is recognized as a foreign substance from the living body. As a result, it shows toxicity to the cells to be cultured and suppresses cell growth, or inflammation occurs at the adhesion site. On the other hand, in the film 10, the content rate of the low molecular substance is suppressed to a predetermined value or less. For this reason, the cells can be cultured without decreasing efficiency, proliferate more efficiently, do not cause inflammation at the adhesion site of the living body, or can be suppressed very mildly even if inflammation occurs.

  It should be noted that the degree of inflammation at the adhesion site when the porous film is adhered to a living body and the degree of decrease in cell culture efficiency when the same porous film is used for cell culture are mutually related. . For example, a porous film with mild inflammation occurring at an adhesion site is unlikely to reduce cell culture efficiency. In addition, a porous film in which inflammation is not observed at the adhesion site tends to maintain or improve cell culture efficiency. Therefore, in evaluating the porous film, if the presence or absence of inflammation at the adhesion site and the degree of inflammation generated are evaluated, the culture efficiency when the porous film is used as a cell culture substrate can be determined. Moreover, if the culture efficiency when a porous film is used as a cell culture substrate is evaluated, the presence or absence of inflammation when the same porous film is adhered to a living body and the degree of inflammation occurring can be understood.

  The effects of suppressing and improving cell culture efficiency and suppressing inflammation at the adhesion site are particularly remarkable when the diameter D of the hole 11 is in the range of 100 nm to 20 μm.

  The effects of suppressing and improving the cell culture efficiency and suppressing inflammation at the adhesion site are particularly remarkable when the hydrophobic polymer is biodegradable. Among the hydrophobic polymers, those that are biodegradable polymers are preferably polylactic acid, polycaprolactone, polyglycolic acid, polydioxanone, polyhydroxybutyrate, and copolymers containing these. In addition, the biodegradable polymer generally has not only biodegradability as a property that is degraded by microorganisms but also properties such as hydrolyzability and bioabsorbability that are unrelated to microorganisms. In the present invention, the biodegradable polymer is not used for utilizing biodegradability involving microorganisms, but is degradable (for example, hydrolyzable) other than biodegradable, soluble in water, Used to take advantage of properties such as ease of absorption.

  The film 10 may contain an amphiphilic compound. As the amphiphilic compound, a phospholipid is preferable.

  The manufacturing method of the film 10 is as follows, for example. As shown in FIG. 4, a film manufacturing process 20 as a first embodiment for manufacturing the film 10 includes a first removal process 21, a solution preparation process 22, a cast film forming process 23, and a film forming process 24. And a second removal step 25.

  The first removal step 21 is a purification step of a hydrophobic polymer that removes low-molecular substances from the hydrophobic polymer 27 that forms the film 10. As a method for removing the low molecular weight substance from the hydrophobic polymer 27, any of known purification methods for polymers may be used, and a reprecipitation method is preferable. This is because the hydrophobic polymer to be purified is literally hydrophobic, and many of the low-molecular substances that inhibit cell culture and cause inflammation at the adhesion site dissolve in water as described above.

  As is well known, the reprecipitation method is a method of purifying a polymer by reprecipitation. The hydrophobic polymer 27 is dissolved in a solvent, and a precipitant is added to this solution to form a precipitate again. This dissolution and precipitation generation may be repeated. As the precipitating agent, water, alcohol or the like may be used. By this reprecipitation method, the low-molecular substance is removed from the hydrophobic polymer 27. By removing the low molecular substance from the hydrophobic polymer 27 that is the raw material in the first removal step 21, the film 10 obtained from the hydrophobic polymer 27 has a low content of the low molecular substance.

  The solution preparation step 22 is a step of preparing a solution 29 for forming the film 10. In this embodiment, the hydrophobic polymer 27 from which the low molecular weight material has been removed by the first removal step 21 is dissolved in the solvent 28 to obtain a solution 29.

  The cast film forming step 23 is a step of forming the cast film 34 by spreading and spreading the solution 29 on the support. It is preferable that the temperature of the support is adjusted in advance, and the temperature is also adjusted while the casting film 34 is formed.

  The film forming process 24 includes a water droplet forming process 32 and an evaporation process 33. The water droplet forming step 32 is a step of forming water droplets by condensation on the film surface of the casting film 34. The water droplets are formed by cooling the support so that the temperature is lower than the temperature of the atmosphere around the casting film 34. However, from the viewpoint of aligning the timing of the generation of a plurality of water droplets or uniforming the size of the formed water droplets, the humidification was performed while adjusting the temperature of the support so that the support was maintained at a predetermined temperature. A gas (for example, air) is preferably supplied onto the casting membrane 34.

  The evaporation step 33 is a step of evaporating the solvent 28 and the water droplets formed in the water droplet formation step 32. Since the holes 11 are formed by forming a water droplet as a mold, the solvent 28 is evaporated earlier than the water droplet so that the water droplet sinks into the casting film 34. For this purpose, it is preferable to use a solvent 28 having a higher evaporation rate than water. However, the timing at which the water droplets start to evaporate may not be after all the solvent 28 has been evaporated. Moreover, as long as the formed holes 11 are maintained, some solvent 28 may remain in the casting film 34 after the evaporation of the water droplets is completed, and the remaining solvent 28 does not evaporate the water droplets. It may evaporate after completion. Thus, the film formation process 24 is a process of a dew condensation method that is well known as a method for producing a porous film.

  The film 10 obtained after finishing the evaporation step 33 is subjected to the second removal step 25. The second removal step 25 is a purification step of the film 10 that removes low molecular substances from the film 10. As a method for removing the low molecular weight substance from the film 10, a method of immersing the film 10 in a hydrophilic liquid is preferable. This is because the film 10 is composed of the hydrophobic polymer 27, and many of the low-molecular substances that inhibit cell culture and cause inflammation at the adhesion site dissolve in water as described above. As the hydrophilic liquid, water and alcohol are preferable. Not only a single substance of water and alcohol but also a mixture of water and alcohol or a mixture of plural kinds of alcohols may be used.

  The film 10 after dipping is dried by applying wind or the like.

  The second removal step 25 removes the low molecular weight material that is not removed in the first removal step 21, and the content of the low molecular weight material in the film 10 is 5% by mass or less. However, when the content of the low molecular weight substance does not become 5% by mass or less, or when the content is further reduced, the second removal step 25 may be repeated or the first removal step 21 may be repeated. Good.

  In the first embodiment, both the first removal step 21 and the second removal step 25 are performed to remove the low molecular weight material, but the low molecular weight material in the film 10 obtained by only one of them is removed. The content may be 5% by mass, and in this case, only one of them may be used.

  The content rate of the low molecular substance in the film 10 is calculated | required by GPC (Gel permeation Chromatography, gel permeation chromatography), for example. Specifically, it is calculated as follows. When the obtained film 10 is graphed by obtaining the molecular weight distribution using commercially available GPC, a curve as shown in FIG. 5 is obtained, for example. In FIG. 5, the vertical axis represents the spectrum intensity, and the horizontal axis represents the molecular weight. In FIG. 5, the horizontal axis is a logarithmic display. The area SA is obtained for the area A surrounded by the curve and the horizontal axis. In FIG. 5, the area A is hatched with diagonal lines. Further, an area SB is obtained for an area B surrounded by a curve having a molecular weight in the range of 0 to 500 and the horizontal axis. In FIG. 5, the area B is hatched with dots. The content (mass%) of the low molecular weight substance is determined by (SB / SA) × 100.

  Moreover, even if the content rate of a low molecular substance is previously made into 5 mass% or less by the said method, the content rate of a low molecular substance increases and exceeds 10 mass% by the process until it uses it. It is assumed that In such a treatment, it is preferable to set conditions so that the content of the low-molecular substance is maintained at 5% by mass or less.

  An example of treatment that may increase the content of low-molecular substances is electron beam sterilization. Electron beam sterilization is a process of sterilizing the film 10 by irradiating the film 10 with an electron beam. Since electron beam sterilization damages organic matter, when the hydrophobic polymer is organic matter, the molecular chain of the hydrophobic polymer is cleaved by electron beam irradiation and the molecular weight is 500 or less. May be generated. Therefore, in the electron beam sterilization, it is preferable to set the electron beam dose to a value lower than a conventionally set value. Thereby, the new production | generation of a low molecular substance is suppressed and the content rate of the low molecular substance in the film 10 is maintained at 5 mass% or less.

  In addition, depending on the conditions, the film 10 may be hydrolyzed during the initial stage of use, and a low-molecular substance may be generated. Therefore, in order to reduce the hydrolysis rate in the initial stage of use, the temperature of the environment where the film 10 is arranged is set to a lower temperature than before, or the area where the film 10 is arranged is sealed. It is preferable to block excessive supply of moisture or remove moisture. Thereby, the content rate of the low molecular substance in the film 10 is maintained at 5 mass% or less.

  As described above, it is preferable to use the film 10 in a state where the content of the low molecular substance in the film 10 is maintained at 5% by mass or less to suppress the generation of the low molecular substance in the initial stage of use. That is, after the film 10 is manufactured, it is preferable to suppress new generation of low-molecular substances.

  In said 1st embodiment, the film 10 obtained by finishing the film formation process 24, ie, finishing the evaporation process 33, is used for the 2nd removal process 25. FIG. However, the manufacturing method of the film 10 is not restricted to said aspect. For example, the film 10 is manufactured also by the film manufacturing process 40 of FIG. A film manufacturing process 40 as a second embodiment for manufacturing the film 10 includes a first removal process 21, a solution preparation process 22, a cast film forming process 23, and a film forming process 41. In addition, in the film manufacturing process 40 of FIG. 6, the same code | symbol as FIG. 4 is attached | subjected about the process common in the film manufacturing process 20 of FIG. 4, and description is abbreviate | omitted.

  The film forming process 41 includes a water droplet forming process 32 and an evaporation process 42. Similarly to the film forming step 24, the film forming step 41 includes a step of a condensation method that is well known as a method for producing a porous film. That is, the evaporation step 42 includes a step of evaporating the solvent 28 and the water droplets formed in the water droplet formation step 32. The evaporation step 42 further includes a third removal step 44.

  The third removal step 44 is a purification step of the casting film 34 that removes low-molecular substances from the casting film 34. As a method for removing low molecular weight substances from the casting film 34, a method of immersing the casting film 34 in a hydrophilic liquid is preferable. The third removal step 44 is performed on the casting film 34 in which the water droplets have been evaporated and the holes 11 are formed, and the casting film 34 used for the third removal step 44 is formed even when immersed in a liquid. As long as the formed holes 11 are maintained, some solvent 28 may remain. The cast film 34 that has been immersed in the liquid is dried by applying air or the like. In addition, when the solvent 28 evaporates with the immersed liquid by drying in the third removal step 44, it is not necessary to separately perform drying for evaporating the solvent 28. If the solvent 28 does not evaporate due to the drying in the third removal step 44, the solvent 28 is evaporated after the third removal step 44 is finished. The dried casting film 34 is peeled off from the support, and the film 10 is obtained.

  From the viewpoint of removing low-molecular substances more reliably and efficiently, it is preferable to immerse the film 10 peeled off from the support in the liquid as in the first embodiment. However, depending on the thickness and porosity of the film 10, the film 10 peeled off from the support may be difficult to handle. In such a case, as in the second embodiment, the casting film 34 may be immersed in the liquid together with the support without being peeled off from the support.

  In the second embodiment, both the first removal step 21 and the third removal step 44 are performed to remove the low molecular weight substance, but the low molecular weight substance in the film 10 obtained by only one of them is removed. The content may be 5% by mass, and in this case, only one of them may be used.

  In addition, when making the content rate of a low molecular substance still lower, it is good to perform the 2nd removal process 25 after the film formation process 41. FIG.

  Although the film 10 has a honeycomb structure in which holes 11 are regularly formed along one film surface 10a, the present invention is not limited to this aspect. For example, like the film 50 shown in FIG.7 and FIG.8, although several hole 51a-51h is formed along one film surface 50a, this invention also includes what does not have regularity in the arrangement | sequence. Of the holes 51a to 51f formed in one film surface 50a, the one that penetrates the other film surface 50b like the hole 51c does not penetrate like the holes 51a, 51b, 51d, 51e, 51f. There may be things. In addition, voids 52 a and 52 b that are not open on any of the film surfaces 50 a and 50 b may be formed inside the film 50. Furthermore, there may be no partition between the hole 51a and the gap 52a or the hole (not shown), and the hole 51a and the gap 52a or the hole (not shown) may be formed continuously with each other. As described above, the present invention includes not only the arrangement of the holes but also the film having irregularities in the shape and size of the holes and having voids that are not open on any film surface.

  The range of the thickness T50 of the film 50 and the diameter D of the holes 51a to 51h is the same as the thickness T10 and the diameter D of the film 10.

  Since the content rate of the low molecular substance in the film 50, the material which comprises the film 50, etc. are the same as that of the film 10, description is abbreviate | omitted.

  The manufacturing method of the film 50 is as follows. As shown in FIG. 9, the film manufacturing process 60 for manufacturing the film 50 includes a first removal process 21, a solution preparation process 22, a film formation process 63, and a second removal process 25. In addition, in the film manufacturing process 60 of FIG. 9, the same code | symbol as FIG. 4 is attached | subjected about the process common in the film manufacturing process 20 of FIG. 4, and description is abbreviate | omitted.

  In this embodiment, the solution preparation step 22 is a solution 69 in which the hydrophilic polymer 67 and the hydrophobic polymer 27 from which the low molecular weight material has been removed by the first removal step 21 are dissolved in the solvent 68.

  The hydrophilic polymer 67 is preferably polyethylene glycol (PEG), polyvinyl alcohol (PVA), polyethylene oxide (PEO), a copolymer of these with a hydrophobic polymer (polylactic acid or the like), or the like. As the solvent 68, both the hydrophobic polymer 27 and the hydrophilic polymer 67 are soluble. When both the hydrophobic polymer 27 and the hydrophilic polymer 67 are not soluble in a single substance, a mixture may be used.

  In the cast film forming step 23, the solution 69 is flowed down and spread on the support to form the cast film 74.

  The film forming process 63 includes a drying process 72 and a dissolving process 73. The drying process 72 is a process of drying the casting film 74. Drying is performed by blowing gas on the casting film 74 or the like. If the temperature is such that the hydrophobic polymer 27 and the hydrophilic polymer 67 do not melt, the gas may be heated to a high temperature, and this high temperature air may be blown onto the casting film 74.

  The dissolution step 73 is a step of dissolving and removing the hydrophilic polymer 67 of the dried casting film 74. In the melting step 73, for example, the casting film 74 is immersed in a water tank containing hot water. The temperature of the hot water is set to a temperature at which the hydrophobic polymer 27 does not melt. When the casting film 74 is immersed in hot water, the hydrophilic polymer 67 is dissolved in the hot water, and the hydrophilic polymer 67 is removed from the casting film 74. The holes 51a to 51h are formed using the hydrophilic polymer 67 as a mold. The method of forming a porous film by dissolving and removing the hydrophilic polymer from the casting membrane containing the hydrophobic polymer and the hydrophilic polymer in this manner is hereinafter referred to as a water extraction method. In the dissolving step 73, after removing the hydrophilic polymer 67, the cast film 74 is dried and peeled off from the support. Drying is performed by applying air to the casting film 74 or the like.

  The film 50 obtained after finishing the dissolution step 33 is subjected to the second removal step 25.

  In this embodiment, both the first removal step 21 and the second removal step 25 are performed to remove the low molecular weight material. However, the low molecular weight material in the film 50 obtained by only one of them is removed. The content may be 5% by mass, and in this case, only one of them may be used.

  Further, in the same manner as in the above-described second embodiment for producing the film 10, instead of at least one of the first removal step 21 and the second removal step 25, the low-molecular substance is removed from the casting film 74. You may implement the 3rd removal process 44 (refer FIG. 6) as a refinement | purification process of the cast film 74. FIG. In addition to the first removal step 21 and the second removal step 25, a third removal step 44 may be performed.

  Examples of the present invention will be described below. Details will be described in Example 1, and Examples 2 to 3 and Comparative Examples 1 to 2 and Reference Example for the present invention will be described only for conditions different from those of Example 1. .

  The film 10 was manufactured by the film manufacturing process 20. However, the 1st removal process 21 in the film manufacturing process 20 was not implemented. In the solution preparation step 22, the hydrophobic polymer 27, the solvent 28, and the amphiphilic compound were provided, and the hydrophobic polymer 27 and the amphiphilic compound were dissolved in the solvent 28. The hydrophobic polymer 27 is polylactic acid (PLLA (product number 719854), manufactured by Sigma-Aldrich Japan), the solvent 28 is chloroform, and the amphiphilic compound is phospholipid (dioleoylphosphatidylethanolamine (DOPE); NOF Co., Ltd., COATSOME ME-8181). The concentration of the hydrophobic polymer 27 in the solution 29 was 1% by mass.

  The solution 29 was cast on a cooled glass plate as a support to form a cast film 34. The cast film 34 was dried while supplying the humidified air to the cast film 34, thereby dew condensation was formed on the surface of the cast film 34 to form water droplets. Finally, the solvent 28 and the water droplets were evaporated. In order to evaporate the water droplets, the air to be blown was switched from humidified to dry. By this film forming step 24, the film 10 having a honeycomb structure in which the holes 11 are arranged along the film surface 10a was formed. Thus, since the film 10 was formed by the dew condensation method in this example, it is described as “the dew condensation method” in the “film formation method” column of Table 1. The film 10 obtained by the film forming step 24 had a uniform pore diameter, and the average pore diameter (average pore diameter) was about 3 μm.

  A second removal step 25 was performed on the formed film 10. The liquid in which the film 10 is immersed is a mixture of ethanol and water. The ethanol concentration in this mixture is 50% by weight. The immersion time was 4 hours. The film 10 was taken out from the liquid and dried. The obtained film 10 had a substantially uniform pore size and an average pore size of about 3 μm. A photomicrograph of the film 10 viewed from the direction perpendicular to the one film surface 10a is shown in FIG. The thickness T10 of the film 10 is described in the “thickness” column (unit: μm) in Table 1.

  The content ratio of the low-molecular substance in the film 10 was determined using GPC both before and after the second removal step 25. A graph of molecular weight distribution obtained by GPC is shown in FIG. The obtained low molecular weight content (unit: mass%) is shown in the “before the second removal step” column of Table 1 for the film 10 before the second removal step 25, and after the second removal step 25. The film 10 is shown in the column “After the second removal step” in Table 1.

About the film 10 which finished the 2nd removal process, the presence or absence of generation | occurrence | production of inflammation in a biological body, and the grade of inflammation were evaluated with the following method. The film 10 was cut into a size of 3 cm × 3 cm to obtain an evaluation sample. The rabbit was laparotomized and an evaluation sample was attached to the outer surface of the intestinal tract. The incised part was closed, and the abdomen was opened again two weeks later. The adhesion site | part of the intestinal tract was observed visually, and the presence or absence and the degree of inflammation were evaluated. The evaluation criteria are as follows. The evaluation results are shown in the “Evaluation results” column of Table 1. The evaluation sample was lost.
A: The adhesion site was not changed compared with the site where the evaluation sample was not adhered, and inflammation was not confirmed.
B: The adhesion site was thin and reddish, but the inflammation was mild.
C: Strong inflammation was observed at the adhesion site.

  The film 50 was manufactured by the film manufacturing process 60. However, the 1st removal process 21 in the film manufacturing process 60 was not implemented. In the solution preparation step 22, the hydrophobic polymer 27, the hydrophilic polymer 67 and the solvent 68 were provided, and the hydrophobic polymer 27 and the hydrophilic polymer 67 were dissolved in the solvent 68. Hydrophobic polymer 27 is polylactic acid (PLLA (product number 719854), manufactured by Sigma-Aldrich Japan), hydrophilic polymer 67 is polyethylene glycol (PEG 6000, manufactured by Wako Pure Chemical Industries, Ltd.), and solvent 68 is Chloroform. The mass of the hydrophobic polymer 27: The mass of the hydrophilic polymer 67 was 40:60. The concentration of the polymer (hydrophobic polymer 27 and hydrophilic polymer 67) in the solution 69 was 5% by mass.

  A cast film 74 was formed by casting the solution 69 on a glass plate as a support that was at room temperature without cooling. The casting film 74 was dried while supplying dried air to the casting film 74, and the drying process 72 was performed to evaporate the solvent 68. The cast film in which the solvent 68 was evaporated was subjected to the dissolution step 73 and immersed in hot water at 80 ° C. for 30 minutes, and PEG was selectively extracted from the cast film and removed. The cast film from which PEG was removed was dried. By this film forming step 63, the film 50 in which the holes 51a to 51h are randomly arranged was formed. Thus, in this example, since the film 50 was formed by the water extraction method, “Water extraction method” is described in the “Film formation method” column of Table 1.

  A second removal step 25 was performed on the formed film 50. The liquid in which the film 10 is immersed is water. The immersion time was 12 hours. The film 50 was taken out from the liquid and dried. The obtained film 50 had a pore diameter in the range of about 500 nm to 3 μm and was non-uniform. FIG. 12 shows a photomicrograph of the film 50 viewed from the direction perpendicular to the one film surface 50a. The thickness T50 of the obtained film 50 is described in the “thickness” column (unit: μm) in Table 1.

  Similar to Example 1, the content of the low molecular weight material in the film 50 was determined using GPC both before and after the second removal step 25. Table 1 shows the content of each low-molecular substance. Further, the presence or absence of inflammation in the living body and the degree of inflammation were evaluated in the same manner as in Example 1 for the film 50 after the second removal step 25. The evaluation results are shown in Table 1.

  A second removal step 25 was performed on the formed film 10. The liquid in which the film 10 is immersed is physiological saline. The immersion time was 1 hour. The film 10 was taken out from the liquid and dried. Other conditions are the same as those in the first embodiment. The obtained film 10 had a substantially uniform pore size and an average pore size of about 3 μm. The thickness T10 of the film 10 is described in the “thickness” column (unit: μm) in Table 1.

  Similar to Example 1, the content of the low molecular weight material in the film 50 was determined using GPC both before and after the second removal step 25. Table 1 shows the content of each low-molecular substance. Further, the presence or absence of inflammation in the living body and the degree of inflammation were evaluated in the same manner as in Example 1 for the film 50 after the second removal step 25. The evaluation results are shown in Table 1.

  The hydrophobic polymer 27 of Example 1 was replaced with polylactic acid (PLLA (product number 81273) Mw = 152000, manufactured by Sigma-Aldrich Japan), and the solution in which the film 10 was immersed in the second removal step 25 was added to physiological saline. Replaced. The time immersed in the liquid was 1 hour. The film 10 was taken out from the liquid and dried. Other conditions are the same as those in the first embodiment. The obtained film 10 had a substantially uniform pore size and an average pore size of about 3 μm. The thickness T10 of the film 10 is described in the “thickness” column (unit: μm) in Table 1.

  Similar to Example 1, the content of the low molecular weight material in the film 10 was determined using GPC both before and after the second removal step 25. Table 1 shows the content of each low-molecular substance. Further, the film 10 after the second removal step 25 was evaluated in the same manner as in Example 1 for the presence or absence of inflammation in the living body and the degree of inflammation. The evaluation results are shown in Table 1.

[Comparative Example 1]
A film was formed by the film forming step 24. The second removal step 25 was not performed on this film. Other conditions are the same as those in the first embodiment. The thickness of the obtained film is shown in Table 1.

  About the film formed by the film formation process 24, the content rate of the low molecular substance was calculated | required using GPC. A graph of molecular weight distribution obtained by GPC is shown in FIG. In this comparative example, since the second removal step was not performed, the obtained low-molecular-weight substance content is shown in the “Before the second removal step” column of Table 1, and the “After the second removal step” column is “− ".

  An evaluation sample was cut out from the film formed in the film forming step 24. For this evaluation sample, the presence or absence of inflammation in the living body and the degree of inflammation were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

[Reference example]
The hydrophobic polymer 27 was subjected to the solution preparation step 22 without going through the first removal step. In the solution preparation step, the hydrophobic polymer 27 was dissolved in the solvent 28 to prepare a solution 29. In preparing the solution 29, no amphiphilic compound was used. The concentration of the hydrophobic polymer in the hydrophobic polymer 27, the solvent 28, and the solution 29 is the same as in Example 1.

  The solution 29 was cast on a glass plate of a support that was at room temperature without cooling to form a cast film. A flat film was formed by supplying dehumidified dry air to the cast film. The second removal step 25 was not performed on this film. The thickness of the obtained flat film is shown in Table 1.

  About the formed flat film, the content rate of the low molecular substance was calculated | required using GPC. In this reference example, since the second removal step was not performed, the obtained low-molecular-weight substance content is shown in the “Before the second removal step” column of Table 1, and the “After the second removal step” column is “− ".

  An evaluation sample was cut out from the formed flat film. For this evaluation sample, the presence or absence of inflammation in the living body and the degree of inflammation were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

10, 50 porous film 11, 51a-51h hole 52 gap

Claims (3)

A casting film forming step of casting a solution in which a hydrophobic polymer is dissolved in a solvent to form a casting film;
A film forming step of forming a porous film having a plurality of holes formed on one film surface from the cast film;
A low molecular substance having a molecular weight of 500 or less is removed from at least one of the hydrophobic polymer, the cast film, and the porous film, so that the content of the low molecular substance in the porous film is 5% by mass or less. A method for producing a porous film, comprising: a removing step to suppress. The method for producing a porous film according to claim 1 , wherein in the removing step, the porous film is immersed in at least one of water and alcohol. The porous film has a plurality of holes formed side by side along one film surface, and has a honeycomb structure when the film surface is viewed from the vertical direction,
The film forming step includes
Forming water droplets by condensation on the cast film;
Method for producing a porous film according to claim 1 or 2, wherein the having the evaporation step to the porous film by evaporating the solvent and water droplets from said casting film.