JP2010070700A - Porous film and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To continuously produce a porous film whose pore arrangement pitches are irregular. <P>SOLUTION: A method for producing the porous film includes: a process for casting a solution comprising an organic solvent and an amphipathic compound on a casting belt 51 to form a cast film 22; a process for dew-condensing to form fine water drops on the cast film 22 in a condition of 3°C≤ΔT≤30°C in the first area 44, wherein ΔT is a value obtained by subtracting the surface temperature TS of the cast film 22 from the dew point TD on the periphery of the cast film 22; a process for growing the fine water drops, immediately after the dew-condensing process, in a condition of 0°C<ΔT≤10°C in the second area 45 so as to bring them into a state of being approximately most densely packed; a process for evaporating a part of the fine water drops in a condition of -3°C<ΔT≤3°C in the third area 46 to reduce the sizes of the fine water drops, thereby moderating the approximately most packed state to make the pore arrangement pitches irregular; a process for evaporating the solvent from the cast film 22 in the fourth area 47; and a process for evaporating the fine water drops from the cast film 22 in a condition of TD<TS in the fifth area 48. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a porous film and a method for producing the same.

  In recent years, in the optical field and the electronic field, there have been increasing demands for higher integration, higher information density, and higher definition of image information. Therefore, it is strongly required to form a finer structure (fine pattern structure) (fine patterning) for films used in these fields. In research in the field of regenerative medicine, a membrane having a fine structure on the surface is effective as a material for cell culture (see, for example, Patent Document 1).

  Various methods such as vapor deposition using a mask, photochemical reaction and photolithographic technique using a polymerization reaction, and laser ablation technique have been put to practical use for fine patterning of a film.

It is also known that a film having a micron-scale honeycomb structure can be obtained by casting a dilute solution of a predetermined polymer under high humidity (for example, see Patent Document 2). A film produced by such a method is said to be a self-assembled film because of the formation behavior of the fine pattern. Other methods for producing a self-assembled film are also proposed in Patent Documents 3 to 6. Further, a film having such a honeycomb structure containing functional fine particles is used as an optical and electronic material. For example, this film is used as a display device by containing a light emitting material body in the film (see, for example, Patent Document 5). Further, the method described in Patent Document 6 regulates the water droplet formation conditions and the water droplet growth conditions, thereby continuously or intermittently producing a porous film having a uniform pore size and shape and pore formation density.
JP 2001-157574 A JP 2002-335949 A JP 2003-151766 A JP 2002-347107 A JP 2003-128832 A JP 2007-291367 A

  As described above, conventionally, the size and pitch of each hole is constant, and the purpose is to manufacture a porous film having a honeycomb structure in which each hole has a close-packed structure. Therefore, the size and pitch of each hole are constant. The manufacturing conditions were optimized so as to be.

  By the way, in the porous film, the size and pitch of the holes are not uniform, and those with poor hole arrangement regularity were also found to be effective in different fields of use. For example, when it is used as an antireflection film, a glaring interference color is observed when the hole arrangement regularity is good, whereas a glare feeling is suppressed when the hole arrangement regularity is inferior. There is an effect. In addition, when cells are cultured, the culture efficiency may be higher in a porous film having randomness than in a porous film having good alignment regularity.

  However, as described above, the conventional manufacturing method aims at a honeycomb structure in which each hole has a close-packed structure, and even if these manufacturing methods are applied as they are, a porous film having poor hole arrangement regularity is obtained. There is a problem that it cannot be manufactured.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a porous film having randomness by relaxing the arrangement regularity of the pores and a production method capable of stably producing the porous film.

  The method for producing a film of the present invention includes a casting step in which a solution containing an organic solvent, an amphiphilic compound having a hydrophilic group and a hydrophobic group, and a polymer compound is cast on a support to form a cast film; When the humidified air is sent to the film and the value obtained by subtracting the surface temperature TS (unit: ° C) of the cast film from the dew point TD (unit: ° C) around the cast film is ΔT, the condition is ΔT> 0. Water droplets are formed by condensation on the cast film, and the water drops are grown and disposed in the cast film, and after the water droplet formation / growth process, the cast film Sending the humidified air, after the sequence irregularity imparting step, the sequence irregularity imparting step of imparting sequence irregularity to the water droplets of the cast film under the condition of −3 ° C. <ΔT <3 ° C., Dew point TD and temperature TS TD <qualify for TS and having a water droplet evaporation step of evaporating the water droplets from the cast film.

The arrangement irregularity imparting step is performed in such a manner that the wind speed V of the humidified air is in a range of 0 (m / s) <V <1.0 (m / s). Further, the water droplet formation / growth step and the arrangement irregularity imparting step are characterized in that the coverage by the water droplets per unit area of the cast film is in the range of 60% to 95%. Further, the water droplet formation / growth step and the arrangement irregularity imparting step are characterized in that the diameter of the water droplets is in the range of 0.1 μm to 100 μm. The water droplet formation / growth step is performed immediately after the water droplet formation step and the water droplet formation step in which condensation is formed on the cast film under the condition of 3 ° C. ≦ ΔT ≦ 30 ° C. by blowing the humidified air. And a water droplet growth step of growing the water droplets under the condition of 0 ° C. <ΔT ≦ 10 ° C. and evaporating the organic solvent from the cast film by blowing the humidified air. The arrangement irregularity imparting step is performed in a state where the viscosity of the cast film is 1 × 10 ⁻³ Pa · s or more and 1 Pa · s or less, and the time for placing the cast film is 30 seconds or more and 20 minutes or less. Features.

  In the porous film of the present invention, the diameter D1 of the micropores is 0.1 μm or more and 100 μm or less, and the coverage per unit area of the micropores is in the range of 60% or more and 95% or less. The center-to-center distance (pitch) P1 varies with the average diameter D1 of the micropores within a range of k1 · D1 <P1 <k2 · D1 (k1 = 1.05, k2 = 4). The arrangement of the micropores is irregular.

  According to the method for producing a film of the present invention, it is possible to relax the arrangement regularity of the holes and stably produce a porous film having randomness. Further, according to the film having randomness in which the pore arrangement regularity of the present invention is relaxed, when it is used as an optical film such as an antireflection film, there is no glare on the film surface, and when it is used as a cell culture film. Depending on the cells, the culture efficiency can be increased.

  As shown in FIG. 1, the film manufacturing process 10 includes a casting process 12, a water droplet formation / growth process 14, an array irregularity imparting process 15, and a water droplet evaporation process 16. Through this process, the porous film 17 is obtained.

  In the casting step 12, a solution described later is cast (cast) on the support 21 (see FIG. 2) to form a cast film 22. Casting includes a method of spreading a solution on a stationary support and a method of spreading the solution on a traveling support, and a method of flowing the solution out of a casting die, and any method can be used in the present invention. The former is generally suitable for producing a variety of products with a small amount of production, that is, the case of producing a small variety of products, and the latter is generally suitable for mass production. In the latter method, when the solution is continuously discharged, a long porous film can be formed, and the solution is intermittently discharged, that is, the flow from the casting die is repeatedly turned on and off for a predetermined time. And a plurality of porous films having a predetermined length can be produced continuously.

  In the water droplet formation / growth step 14, first, as shown in FIGS. 2A and 2B, dew condensation is caused on the cast film 22 by blowing humidified air to the cast film 22. The water droplet 25 generated at this time is very small and cannot be recognized with the naked eye. Next, the water droplet 25 is grown slowly. The purpose of this water droplet growth is to combine a plurality of extremely small water droplets generated by condensation to enlarge the water droplets. However, depending on the temperature of the cast film 22 and the conditions around the cast film 22, There may be a phenomenon in which each small water droplet becomes a nucleus and grows larger. The solvent 26 contained in the cast film 22 is evaporated at least either during or after the water droplet growth. As a result, the water droplet 25 enters the cast film 22 as shown in FIG. Instead of the water droplet 25, other droplets may be used.

Then, when the water droplets 25 are in a substantially close-packed state, as shown in FIG. 2D, in the arrangement irregularity imparting step 15, a part of the water droplets 25 is evaporated, thereby reducing the water droplet size. Thus, it is possible to relax the substantially close-packed state and make the pitches p1 between the water droplets uneven.
Therefore, in this state, in the subsequent water droplet drying step, the porous film 17 having the uneven pitch P1 between the holes is obtained as shown in FIG.

In the arrangement irregularity imparting step 15, the cast film has a viscosity of 1 × 10 ⁻³ Pa · s or more and 1 Pa · s or less, and the time for placing the cast film in the third area is 30 seconds or more and 20 minutes or less. To do. If the viscosity of the cast film exceeds 1 Pa · s, the fluidity is low, so that the water droplets are fixed and it becomes difficult to make the arrangement irregular. If the time for which the cast film is placed in the third area is less than 30 seconds, the irregularization becomes insufficient, and if it exceeds 20 minutes, the water droplets that serve as the mold may disappear.

  In the water droplet evaporation step 16, the water droplet 25 in the cast film 22 is evaporated as water vapor 27 as shown in FIG. When the solvent 26 remains in the cast film 22, the conditions are such that the water droplet 25 is evaporated after the solvent 26 is evaporated as much as possible. In this way, the porous film 17 can be formed on the support 21. If the support 21 is unnecessary when used, the porous film 17 may be peeled off after or during the formation.

  In FIG. 3 showing the outline of the porous film of the present invention, the porous film 17 peeled off from the support 21 (see FIG. 2) has a large number of densely formed holes. The holes 31 are formed inside the porous film 17 as shown in FIG. The holes 31 are substantially circular, and the pitches P1 of the holes are not uniform. As shown in (B), the hole 31 may be formed so as to penetrate both surfaces of the porous film 17 or may be formed as a depression on one side, although not shown. In addition, the hole 31 and the dent may communicate with each other, or may be arranged independently without communicating.

  Although the thickness of the porous film 17 manufactured by this invention is not specifically limited, For example, when manufacturing the porous film 17 whose thickness L1 is 0.05 micrometer or more and 100 micrometers or less, or the diameter D1 of the hole 31 is 0.00. This is particularly effective when the porous film 17 is manufactured in such a manner that the distance P1 between the centers of the adjacent holes 31 is not less than 0.1 μm and not more than 100 μm.

  The hole diameter D1 varies in the range of 0.1 to 100 μm, and the pitch P1 varies in the range of 0.1 to 400 μm. The variation amount is preferably ± 25% or less, more preferably ± 15% with respect to the average value of the pore diameter D1. Further, the numerical range of the pitch P1 is preferably ± 25% or less, more preferably ± 15% with respect to the average value of the pitch P1.

  Hereinafter, the manufacturing method of the porous film 17 of this invention is demonstrated. The porous film 17 includes a polymer compound and an amphiphilic compound. Amphiphilic compounds have hydrophilicity and lipophilicity, and specifically are compounds having a hydrophilic group and a hydrophobic group. When the polymer compound has amphiphilic properties, the polymer compound and other amphiphilic compounds may not be used in combination. Moreover, when using a high molecular compound which cannot be said to have amphiphilicity, it is preferable to use a high molecular compound and an amphiphilic compound in combination.

  Although the high molecular compound as a main component of the porous film 17 can be determined according to a use etc., that whose number average molecular weight (Mn) is 10,000-10,000,000 is preferable, 50, What is 000-1,000,000 is more preferable.

  There is no restriction | limiting in particular as said hydrophobic polymer, According to the objective, it can select suitably according to the objective, For example, vinyl polymer (For example, polyethylene, polypropylene, polystyrene, polyacrylate, polymethacrylate, polyacrylamide) , Polymethacrylamide, polyvinyl chloride, polyvinylidene chloride, polyvinylidene fluoride, polyhexafluoropropene, polyvinyl ether, polyvinyl carbazole, polyvinyl acetate, polyvinyl carbazole, polytetrafluoroethylene, etc., polyester (eg, polyethylene terephthalate, polyethylene) Naphthalate, polyethylene succinate, polybutylene succinate, polylactic acid, etc.), polylactone (eg polycaprolactone, etc.), polyamide or poly Imides (such as nylon and polyamic acid), polyurethane, polyurea, polybutadiene, polycarbonate, polyaromatics, polysulfone, polyethersulfone, polysiloxane derivatives, cellulose acylate (triacetyl cellulose, cellulose acetate propionate, cellulose acetate) Butyrate). From the viewpoints of solubility, optical physical properties, electrical physical properties, film strength, elasticity, etc., these may be homopolymers as necessary, or may take the form of copolymers or polymer blends. In addition, you may use these polymers as a mixture of 2 or more types of polymers as needed. For use in optical applications, for example, cellulose acylate and cyclic polyolefin are preferred.

  An example of the polymer compound having amphiphilic properties is polyacrylamide. Other amphiphilic polymer compounds include polyacrylamide as a main chain skeleton, a dodecyl group as a lipophilic side chain, a carboxyl group as a hydrophilic side chain, and a polyethylene glycol / polypropylene glycol block copolymer. The lipophilic side chain is a non-polar linear group such as an alkylene group or a phenylene group, and has a hydrophilic group such as a polar group or an ionic dissociation group to the end, excluding a linking group such as an ester group or an amide group. A structure that does not branch is preferable. For example, when using an alkylene group, the lipophilic side chain preferably comprises 5 or more methylene units. The hydrophilic side chain preferably has a structure having a polar part, an ionic dissociation group, or a hydrophilic part such as an oxyethylene group at the terminal via a linking part such as an alkylene group.

  As an amphiphilic compound used by mixing with a polymer compound, an oligomer such as a dimer or trimer, or a polymer compound is used in addition to many monomers such as commercially available surfactants. be able to. By mixing the amphiphilic compound with the polymer compound, water droplets are easily formed on the exposed surface of the cast film. Further, by controlling the dispersion state with respect to the polymer compound, the position where water droplets are formed can be more easily controlled. When a polymer compound and an amphiphilic compound are used in combination, water droplets are formed when the ratio of the weight of the amphiphilic compound to the weight of the polymer compound is in the range of 0.1% to 20%. Therefore, it is easy to obtain a film having uniform holes. If the ratio of the weight of the amphiphilic compound to the weight of the polymer compound is less than 0.1%, there is almost no effect of adding the amphiphilic compound, and the formed water droplets are unstable and non-uniform in size. There is a case. On the other hand, when the ratio of the weight of the amphiphilic compound having a low molecular weight to the weight of the polymer compound is larger than 20%, the strength of the porous film may be lowered.

  The amphiphilic compound to be mixed with the polymer compound preferably has (number of hydrophilic groups) :( number of hydrophobic groups) of 0.1: 9.9 to 4.5: 5.5. Thereby, finer water droplets can be formed more densely on the cast film 22. When (the number of hydrophilic groups): (the number of hydrophobic groups) is not included in the above range, the pore sizes vary greatly. Specifically, {(standard deviation of pore diameter) / (pore size (Average value)} × 100 The pore diameter variation coefficient (unit:%) may be 10% or more. In addition, when (number of hydrophilic groups) :( number of hydrophobic groups) is not included in the above range, the regularity of the pore arrangement may be disturbed.

  It is preferable to use two or more kinds of amphiphilic compounds which are different from each other, since the formation position of the water droplet and the size of the water droplet can be controlled. Moreover, the same effect can be acquired also about a high molecular compound by using 2 or more types of compounds which are mutually different.

  The solvent used as the solvent of the solution is not particularly limited as long as it is hydrophobic and can dissolve the polymer compound. Examples include aromatic hydrocarbons (eg, benzene, toluene, etc.), halogenated hydrocarbons (eg, dichloromethane, chlorobenzene, carbon tetrachloride, 1-bromopropane, etc.), cyclohexane, ketones (eg, acetone, methyl ethyl ketone, etc.) , Esters (eg, methyl acetate, ethyl acetate, propyl acetate, etc.) and ethers (eg, tetrahydrofuran, methyl cellosolve, etc.). Among these, a plurality of compounds may be used in combination as a solvent. Moreover, you may use what added hydrophilic solvents, such as alcohol and ketones, about 20% or less to the simple substance or mixture of these compounds.

  By using two or more different compounds as the solvent and changing the ratio as appropriate, the formation speed of the water droplets, the depth of penetration of the water droplets into the cast film 22 and the like can be controlled.

  About a solution, it is preferable that a high molecular compound shall be 0.02 weight part or more and 20 weight part or less with respect to 100 weight part of organic solvents. Thereby, a high-quality porous film can be manufactured with high productivity. When the polymer compound is less than 0.02 parts by weight with respect to 100 parts by weight of the organic solvent, the solvent ratio in the solution is too large, and the time required for evaporation becomes long. If it exceeds 50%, water droplets generated by condensation cannot deform the solution in the cast film, so that a porous film having uneven irregularities may be formed.

  As for the solution, the higher the viscosity, the worse the mobility of water droplets generated by dew condensation, and the lower the viscosity, the water droplets combine and coalesce and the pore size tends to be non-uniform. And if this viscosity is made into the range of 0.1 mPa * s or more and 50 mPa * s or less, the porous film with a more uniform hole can be manufactured. Therefore, in order to obtain a substantially close-packed state of water droplets having a desired pore diameter and arrangement within a certain range, it is preferable to set the viscosity range. When the viscosity of the solution is less than 0.1 mPa · s, arbitrary water droplets are connected, and it becomes difficult to control the pore diameter and arrangement within a desired range. On the other hand, if it is greater than 50 mPa · s, water droplets do not sink into the film and a porous film cannot be formed. In addition, the arrangement of the water droplets is disturbed, and the water droplets cannot be formed.

  In FIG. 4 which shows the outline of the manufacturing apparatus 41 of a porous film, before sending the solution 42 to the film manufacturing equipment 41, it has filtered beforehand, and can prevent mixing of the foreign material to the porous film 17 by this. Filtration is preferably performed a plurality of times. For example, when the filtration is performed twice, the upstream filtration device (not shown) is provided with a filter having an absolute filtration accuracy (absolute filtration pore diameter) larger than the pore diameter of the porous film 17, The filtration device (not shown) is preferably provided with a filter having an absolute filtration accuracy smaller than the gap of the porous film 17.

  The casting step 12, the water droplet formation / growth step 14, the arrangement irregularity imparting step 15, and the water droplet evaporation step 16 are all performed in the casting chamber 43. The solvent that has become a gas in the casting chamber 43 is recovered by a recovery device (not shown) and then regenerated by a regeneration device (not shown) provided outside the casting chamber 43 for reuse. The

  In the present embodiment, the partition 43a is provided in the casting chamber 43, so that the first to fifth areas 44 to 48 are divided into five rooms. In the first area 44, the casting die 56 and water droplets are formed. The blower suction unit 61 includes a blower suction unit 63, 64 for water droplet growth in the second area, a blower suction unit 65 for providing array irregularity in the third area, and solvent evaporation and evaporation in the fifth area 48. Air-blowing suction units 71 to 74 for evaporating water droplets are respectively arranged. Although the fourth area 47 is not provided with a blast suction unit, a blast suction unit for solvent evaporation may also be arranged in the fourth area 47. Note that the number of divisions of the area is not limited to that in the illustrated example, but may be a plurality.

  A casting belt 51 used as a support is stretched around rollers 52 and 53, and a casting die 56 is provided above the casting belt 51. At least one of the rollers 52 and 53 is rotated by a driving device (not shown), whereby the casting belt 51 continuously runs. In addition, the temperature of the rollers 52 and 53 is adjusted by the temperature controller 54, and the temperature of the casting belt 51 in contact with the rollers 52 and 53 is controlled.

Casting belt 51 has a thermal conductivity k and a thickness L is preferably not satisfy those ^{100W / (m 2 · K)} ≦ k / L ≦ 100000W / (m 2 · K). The thickness L is preferably 0.05 mm or more and 10 mm or less. This enables faster and more precise temperature control. In particular, such a casting belt 51 is effective when the ambient air condition control of the cast film 22 cannot be changed instantaneously.

  Further, a flat plate member or a flexible sheet (flexible sheet) as a second support is arranged on the casting belt 51, and a cast film is formed on the second support. Also good. On the other hand, it is preferable to use a flat plate member or a flexible sheet instead of the casting belt 51, each of which includes a Peltier module. By arranging these flat plate members and flexible sheets on members that are temperature-controllable and have a horizontal surface, the temperature can be controlled with high accuracy for each flat plate member or each flexible sheet.

  In the first area 44, when the solution 42 flows out from the casting die 56, the cast film 22 is formed on the casting belt 51. A blower suction unit 61 is provided above the traveling path of the cast film 22. The blower suction unit 61 has a blower port 61a for letting humid air in the vicinity of the cast film 22 and an intake port 61b for sucking and exhausting gas around the cast film 22, and the temperature, dew point, and humidity of the wind in the blower system. A wind controller (not shown) for independently controlling the wind speed and the suction force in the intake system. The air outlet 61a is provided with a filter for maintaining the dustiness, that is, the cleanliness of the humidified air. A plurality of blower suction units 61 may be provided side by side in the running direction of the casting belt 51.

Here, when the dew point (first dew point) of the wind from the air outlet 61a is TD1, the value obtained by TD1-TS is the first temperature difference ΔT1. At least one of the surface temperature TS and the first dew point TD1 is controlled so that the first temperature difference ΔT1 satisfies the following formula (1). The surface temperature TS of the cast film 22 can be measured by providing non-contact temperature measuring means such as a commercially available infrared thermometer in the vicinity of the cast film 22. If the first temperature difference ΔT1 is less than 3 ° C., water droplets are less likely to be generated. On the other hand, if the first temperature difference ΔT1 is greater than 30 ° C., water droplets are abruptly generated and the size of the water droplets is uneven. Or water droplets may be two-dimensional, that is, three-dimensionally overlapped without being arranged in a plane. In the first area 44, the first temperature difference ΔT1 is preferably changed from a large value to a small value. Thereby, the generation speed of the water droplets and the size of the generated water droplets can be controlled, and the two-dimensional water droplets having a uniform diameter in the surface direction of the cast film 22 can be formed.
3 ° C. ≦ ΔT1 ≦ 30 ° C. (1)

  In the first area 44, the surface temperature TS of the cast film 22 is controlled by the casting belt 51 and the temperature control plate 60 disposed facing the casting belt 51, but controlled by either one. May be. Further, the first dew point TD1 is controlled by controlling the condition of the humidified air emitted from the blower suction unit 61.

  In the second area 45, two air suction units 63 and 64 are arranged in order along the traveling path of the cast film 22. The upstream air suction unit 63 is located immediately downstream of the air suction unit 61 in the first area 44. This is because the water droplets formed in the first area 44 are uniformly grown. As the first area 44 and the second area 45 are separated from each other, that is, as the time from the formation of the water droplet to the entry into the second area 45 becomes longer, the size of the water droplet when grown is more uneven. End up. The number of the air suction units 63 and 64 is not limited to the number of the present embodiment, that is, 2 and may be 1 or 3 or more. The air suction units 63 and 64 are the same as the air suction unit 61, but are not limited thereto.

  In the second area 45, at least one of the surface temperature TS and the second dew point TD2 is controlled so that the second temperature difference ΔT2 (= TD2-TS) satisfies the following formula (2). The surface temperature TS is mainly controlled by the temperature control plate 60. The temperature control plate 60 has basically the same structure as the temperature control plate 60 in the first area 44, and can change the temperature along the traveling direction of the casting belt 51. Further, the control of the second dew point TD2 is made by the condition control of the humidified air from the air blowing port 63a. In the second area 45, the surface temperature TS of the cast film 22 can be measured by providing a temperature measuring means similar to the above in the vicinity of the cast film 22.

By setting the conditions of the second area 45 in this way, it is possible to grow water droplets slowly and promote the arrangement of the water droplets by capillary force, so that substantially uniform water droplets can be densely formed. When the second temperature difference ΔT2 is 0 ° C. or less, the growth of water droplets is insufficient and does not form a dense state, and the shape and size of the holes and the arrangement of the holes in the porous film may be uneven. . In addition, if the second temperature difference ΔT2 is greater than 10 ° C., water droplets are locally multilayered, that is, three-dimensionally formed, and the shape and size of the holes and the arrangement of the holes in the porous film are not uniform. There is.
0 ° C <ΔT2 ≦ 10 ° C (2)

  It is preferable to evaporate as much solvent from the cast film 22 as possible while growing the water droplets. By setting the surface temperature TS and the second dew point TD2 in the second area 45 within the above ranges, the solvent can be sufficiently evaporated and rapid evaporation can be suppressed. Further, it is preferable to selectively evaporate only the solvent without evaporating the water droplets. Therefore, a solvent having a higher evaporation rate than water droplets under the same temperature and pressure is preferable. This makes it easier for water droplets to enter the cast film 22 as the solvent evaporates.

  In this embodiment, the water droplet formation / growth process is configured by using two areas of the first area 44 and the second area 45 and setting the temperature differences ΔT1 and ΔT2 under different temperature conditions. However, the present invention is not limited to this, and the temperature of the water droplet formation / growth process may be controlled by one temperature difference ΔT1.

  In the third area 46, one blower suction unit 65 is arranged along the traveling path of the cast film 22. The air suction unit 65 is located immediately downstream of the air suction unit 64 in the second area 45. This is because the water droplets are reduced by evaporating a part of the water droplets that are formed in the second area 45 and are close-packed. In addition, the number of the ventilation suction units 65 may be one or more. Moreover, although the ventilation suction unit 65 is made the same as the ventilation suction unit 61, it is not limited to this.

In the third area 46, at least one of the surface temperature TS and the third dew point TD3 is performed in the same manner as in the second area 45 so that the third temperature difference ΔT3 (= TD3-TS) satisfies the following expression (3). Control either one. The surface temperature TS is mainly controlled by the temperature control plate 60. Further, the control of the third dew point TD3 is made by the condition control of the humidified air from the blower port 65a.
−3 ° C. <ΔT3 <3 ° C. (3)

  If ΔT3 is −3 ° C. or lower, water droplets disappear and a porous film cannot be obtained. Conversely, if ΔT3 is + 3 ° C. or higher, the arrangement regularity becomes insufficient. In the third area 46, it is desirable that the surface temperature TS is substantially equal to the third dew point TD3. The wind speed V of the humidified air is in the range of 0 (m / s) <V <1.0 (m / s). Preferably, 0.01 (m / s) <V <0.5 (m / s), and more preferably 0.02 (m / s) <V <0.3 (m / s). . When the wind speed V becomes 0, water droplets disappear and a porous film cannot be obtained. On the other hand, when the wind speed V is 1.0 (m / s) or more, water droplets formed on the solution surface may be disturbed and streaky irregularities may be formed, which is not preferable.

  Here, the substantially close-packed state of water droplets refers to a state one step before the close-packed state. In the close-packed state, the water droplets have the same size, and the distance between the water droplets is also constant, resulting in a six-way close-packed state (honeycomb structure) when viewed from the plane (see FIG. 5A). In the substantially close-packed state, the size of each water droplet is substantially constant, but the pitch of the holes is not uniform, and the close-packed structure is broken. This substantially close-packed state refers to a state where the number of water droplets filled per unit area is 60 to 95% of the close-packed state (see FIG. 5B). By evaporating a part of each water droplet, each water droplet becomes small. In addition, when some of the water droplets evaporate and become smaller, gaps are formed between the water droplets, and the gaps are not uniform, so that the shape of the water droplets changes from a sphere, and the sphere is distorted. Since the movement is caused by the change in the gap, the pitches that are the distances between the water droplets are also uneven.

  FIG. 5 is a photograph for explaining the state of water droplets in the step of imparting array irregularity, and is a photograph of the dried porous film viewed with an electron microscope. (A) shows a porous film having a hexagonal close-packed structure in which water droplets are dried without performing the sequence irregularity imparting step of the present invention after passing through the close-packed state. Moreover, (B) shows the porous film of the present invention in which the arrangement irregularity imparting step of the present invention is performed in a substantially close-packed state and the sizes and pitches of the respective water droplets are irregular. As is clear from this photograph, in the present invention, the pitch is uneven, and it is presumed that this uneven state is substantially the same pattern before the water droplets are dried.

  In the fifth area 48, four blower suction units 71 to 74 are arranged in order along the traveling path of the cast film 22. The number of blower suction units is not limited to the number of the present embodiment, that is, four, and may be one or more. The air suction units 71 to 74 are the same as the air suction unit 61, but are not limited thereto. In the fifth area 48, the drying of the solvent is promoted in a state in which the evaporation of the water droplets is suppressed, the casting mold solvent is held by the water droplets to evaporate the solvent of the cast film, and then the water droplets are evaporated to form the porous film 17. .

In the fifth area 48, at least one of the surface temperature TS and the fourth dew point TD4 so that the temperature difference ΔT4 (= TD4-TS) obtained by subtracting the surface temperature TS from the fourth dew point TD4 satisfies the following formula (4). Control either one. The surface temperature TS is controlled mainly by the temperature control plate 76. Further, the dew point control is performed by controlling the condition of the dry air from the air blowing port 63a. In the fifth area 48, the surface temperature TS of the cast film 22 can be measured by providing a temperature measuring means similar to the above in the vicinity of the cast film 22. By setting the conditions of the fifth area 48 in this way, it is possible to produce a porous film 17 to which irregularity is imparted by stopping the growth of water droplets and evaporating. If TS ≦ TD4, further condensation may occur on the water droplets and the formed porous structure may be destroyed.
0> ΔT4 (4)

  In the fifth area 48, the main purpose is to evaporate water droplets, but the solvent that could not be evaporated before reaching the fourth area 47 is also evaporated.

  In the water droplet evaporation process in the fifth area 48, a reduced pressure drying device or a so-called 2D nozzle may be used in place of the blower suction units 71 to 74. By performing drying under reduced pressure, it becomes easier to adjust the evaporation rates of the solvent and water droplets, respectively. As a result, the evaporation of the organic solvent and the evaporation of the water droplets can be made better, and the water droplets can be formed inside the cast film 22 better. Therefore, the size and shape are controlled at the position where the water droplets are present. A hole 31 can be formed. The 2D nozzle has an air supply nozzle member that emits air and an exhaust nozzle member that sucks air in the vicinity of the cast film 22. The 2D nozzle is preferably one that can uniformly supply and exhaust air over the entire width of the cast surface. The temperature of the casting belt 51 is preferably gradually increased from the first area 44 to the fifth area 48. Thereby, the solvent can be efficiently evaporated without controlling the evaporation rate and destroying the porous structure. This temperature increase is preferably performed in the range of 0.005 ° C./second or more and 3 ° C./second or less.

  The film manufacturing equipment 41 further includes a peeling roller 57 that supports the porous film 17 peeled off from the casting belt 51 when the cast film 22 is peeled off from the casting belt 51, and the porous film is sent to the next process. . The next step is, for example, a function providing step for applying various functions to the porous film 17, a winding step for winding the porous film 17 into a roll shape, or the like.

  In the present invention, the air blowing speed of the humidified air from the air blowing and suction units 61, 63, 64 is 0.05 m / second or more and 2 m / second relative to the moving speed of the cast film 22, that is, the traveling speed of the casting belt 51. The range is preferably in the following range, more preferably in the range of 0.1 m / sec to 1.5 m / sec, and most preferably in the range of 0.1 m / sec to 1.0 m / sec. If the relative speed is less than 0.05 m / sec, the cast film 22 may be introduced into the fifth area 48 (see FIG. 4) before the water droplets are not provided with non-uniformity. On the other hand, if the relative speed exceeds 2 m / sec, the exposed surface of the cast film 22 may be disturbed, or condensation may not sufficiently proceed.

  In addition, the porous multilayer film which laminated | stacked the porous film and the film which consists of a functional material can be manufactured using the film which consists of various functional materials as a support body.

  Moreover, although the water droplet formation / growth step is configured by continuously performing the water droplet formation step and the water droplet growth step, these steps may be performed separately as two steps. In the water droplet formation step, dew condensation is formed on the cast film under the conditions of 3 ° C. ≦ ΔT ≦ 30 ° C. by blowing humidified air to form water droplets. Immediately after the water droplet formation step, in the water droplet growth step, water droplets are grown under the condition of 0 ° C. <ΔT ≦ 10 ° C. by blowing the humidified air, and the organic solvent is evaporated from the cast film.

  In this embodiment, although the case where the elongate porous film 17 was manufactured by casting the solution 42 continuously was illustrated, this invention is not limited to this. For example, the case where the solution 42 is intermittently cast to sequentially produce sheet-like porous films is also included. FIG. 6 is a schematic diagram of a main part of a film production facility according to another embodiment. In addition, the same code | symbol as FIG. 4 is attached | subjected about the apparatus and member of the same effect | action as FIG.

  A film production facility 81 for producing a sheet-like porous film includes a first area 86 for casting the solution 42 on a support 85 to condense, a second area 87 for growing water droplets to evaporate the solvent, It has the 3rd area 88 which evaporates one part and makes the size and pitch of each water droplet uneven, and the 4th area 89 which evaporates a water droplet.

  In the first area 86, the solution 42 is cast from the casting die 56 while the support 85 is being conveyed, and a cast film 91 is formed. And the support body 85 in which the cast film | membrane 91 was formed is conveyed downstream by the conveyance belt 92, and a water droplet is formed by dew condensation. Thereafter, the cast film 91 on which water droplets are formed is transported to the second area 87 by the transport belt 92 together with the support body 85. In the second area 87, water droplets grow. Thereafter, the cast film 91 into which water droplets have entered is conveyed to the third area 88, where some of the water droplets are evaporated, and the pitch between the water droplets becomes uneven. Thereafter, the cast film 91 in which the nonuniformity is imparted to each water droplet is conveyed to the fourth area 89, where the water droplet is evaporated. Thus, each process in each area 86-89 is implemented per support body, and a sheet-like porous film can be manufactured by conveying the support body 85 intermittently. In addition, the temperature conditions, air blowing conditions, etc. by the 1st-4th areas 86-89 are performed similarly to 1st Embodiment.

  Further, a cast film having a smaller width can be formed by arranging a plurality of casting dies having a casting width narrower than that of the casting die 56 in the width direction of the support. Furthermore, a plurality of smaller cast films can be formed on the support by intermittently transporting the support in the casting process at shorter time intervals. In addition, a strip-shaped porous film can be produced one after another by dividing the solution outlet of the casting die into a plurality in the width direction and casting the solution 42 intermittently.

  In the above embodiment, the irregularity of the holes is increased, but in addition to this, the holes may be non-uniform in size. In this case, for example, the moisture evaporation from the water droplet 25 is prioritized immediately before the closest packed state. At this time, each water droplet 25 is in a state before the diameter d1 becomes substantially uniform, and the size of the water droplets varies. In this state, priority is given to the evaporation of the water in the water droplets 25 to reduce the size of the water droplets 25, thereby promoting variation in the size of the water droplets 25. Further, when the variation in the size of the water droplets 25 is promoted and the variation in the pitch p1 between the water droplets also varies, each water droplet 25 moves or deforms in the cast film 22 according to the variation. Thereby, the dispersion | variation in the pitch p1 between each water droplet 25 is accelerated | stimulated. As a result of promoting the variation in the diameter d1 of the water droplets 25 and the pitch p1 between the water droplets, the shape, the diameter d1, and the pitch p1 of the water droplets 25 are uneven, and the arrangement regularity is lowered. In this state, in the subsequent water droplet drying step, the porous film 17 in which the size (diameter) D1 of the holes 31 and the pitch P1 between the holes are not uniform as shown in FIG. It is done.

  Hereinafter, although an example of the present invention is given and explained, the present invention is not limited to this. In addition, Example 1 will be described in detail, and for other Examples 2 to 4 and Comparative Examples 1 and 2, only the parts different from the conditions in Example 1 will be described, and the same conditions as in Example 1 will be described. Abbreviated.

[Example 1]
A film having a honeycomb structure in which holes penetrated in the plane direction and the thickness direction of the film and arranged in the plane direction was manufactured. Polycarbonate (Iupilon H-3000 manufactured by Mitsubishi Engineer Plastics Co., Ltd.) as a polymer compound, polyalkylacrylamide as an amphiphilic compound and polymer compound, and dichloromethane as a solvent were prepared. A polyalkylacrylamide having a hydrophilic group number / hydrophobic group number of 2.5 / 7.5 was used. A solution was prepared by dispersing and mixing 2.0 mg / ml of polycarbonate and 0.2 mg / ml of polyalkylacrylamide in a solvent. This solution was cast on the casting belt 51. The viscosity of the solution subjected to casting is 1 mPa · s.

  The cast film 22 sequentially passed through the first to fifth areas 44 to 48 by running the support 21. The conditions of ΔT in each area 44 to 46, 48 were set as shown in Table 1. In Example 1, the temperature difference ΔT1 in the water droplet formation / growth zone (condensation zone) is 8 ° C., the temperature difference ΔT2 in the array irregularity imparting step is 1 ° C., the wind speed is 0.3 m / s, and the zone residence time is 3 minutes. The temperature difference ΔT3 of the drying zone was set to −10 ° C. The obtained porous film had an average pore size of 8.3 μm and a coefficient of variation of 7.2%. In the evaluation of arrangement regularity, it was “X”.

  The arrangement regularity was evaluated by a diffraction experiment by laser scattering. A laser (wavelength: 672 nm, InGaAlP, spot diameter: about 400 μm, manufactured by Sigma Koki Co., Ltd.) was incident perpendicularly to the film surface, and a diffraction spot was projected onto the screen. When the arrangement regularity is high, high-order diffraction spots are confirmed. On the other hand, when the hole diameter is uniform but the arrangement is low, the projected laser light is confirmed as a multiple ring. Therefore, according to the results of the diffraction experiment by laser scattering, when multiple rings are observed (the pore diameters are uniform, but the arrangement regularity is low and the glare feeling is low), it is evaluated as “X” and replaced with the multiple rings. When a diffraction spot was observed (high ordering regularity and a lot of glare), it was evaluated as “Y”, and other cases were evaluated as “Z”.

[Example 2]
Same as Example 1 except that the temperature difference ΔT2 in the condensation zone was 5 ° C., the temperature difference ΔT1 in the sequence irregularity imparting step was 3 ° C., the wind speed was 0.05 m / s, and the residence time in this zone was 5 minutes. Condition. The obtained porous film had an average pore diameter of 5.3 μm and a coefficient of variation of 8.1%. Moreover, it became "X" in the arrangement | sequence regulatory evaluation.

[Example 3]
Example 1 except that the temperature difference ΔT2 in the condensation zone was 10 ° C., the temperature difference ΔT1 in the sequence irregularity imparting step was 0 ° C., the wind speed was 1.0 m / s, and the residence time in this zone was 20 minutes. Condition. The obtained porous film had an average pore diameter of 6.7 μm and a coefficient of variation of 7.3%. In the evaluation of arrangement regularity, it was “X”.

[Example 4]
Example 1 except that the temperature difference ΔT2 in the condensation zone was 15 ° C., the temperature difference ΔT1 in the sequence irregularity imparting step was −3 ° C., the wind speed was 0.5 m / s, and the residence time in this zone was 30 seconds. The same conditions were used. The obtained porous film had an average pore diameter of 7.0 μm and a coefficient of variation of 8.1%. Moreover, it became "X" in the arrangement | sequence regulatory evaluation.

[Comparative Example 1]
Same as Example 1 except that the temperature difference ΔT2 in the condensation zone was 8 ° C., the temperature difference ΔT1 in the sequence irregularity imparting step was 5 ° C., the wind speed was 0.2 m / s, and the residence time in this zone was 3 minutes. Condition. The obtained porous film had an average pore size of 8.7 μm and a coefficient of variation of 4.9%. Moreover, it became "Y" in arrangement | sequence regulatory evaluation.

[Comparative Example 2]
Example 1 except that the temperature difference ΔT2 in the condensation zone was 8 ° C., the temperature difference ΔT1 in the sequence irregularity imparting step was −5 ° C., the wind speed was 0.5 m / s, and the residence time in this zone was 30 minutes. The same conditions were used. The obtained porous film had an average pore size of 7.6 μm and a coefficient of variation of 14.0%. Moreover, it became "Z" by arrangement | sequence regulatory evaluation.

  As described above, irregularity can be imparted to the pore arrangement of the porous film by performing the arrangement irregularity imparting step of the present invention. When the porous film thus obtained (see FIG. 5B) is used as an antireflection film, it can suppress a glare feeling as compared with a film having good hole arrangement regularity. Further, when cells are cultured, the culture efficiency can be increased as compared with a porous film having good alignment regularity.

It is process drawing explaining the manufacturing method of the film which concerns on this invention. It is explanatory drawing of the state in which the film which concerns on this invention is formed. (A) is a top view of the film which concerns on this invention, (B) is sectional drawing which follows the bb line of (A). It is the schematic of a film manufacturing equipment. It is an electron micrograph of a porous film, and (A) shows that the water droplets are in the closest packing state in the second area without performing the sequence irregularity imparting step of the present invention, and then the water droplets are evaporated in the fourth area. The resulting porous film having a honeycomb structure is shown, and (B) shows the porous film in which the sizes, shapes, and pitches of the holes are made uneven by the manufacturing method of the present invention. It is the schematic of the film manufacturing apparatus as another embodiment. (A) is a top view of the film in another embodiment which concerns on this invention, (B) is sectional drawing which follows the bb line of (A).

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Film manufacturing process 12 Casting process 14 Water drop formation and growth process 15 Water drop evaporation process 17 Porous film 21 Support body 22 Cast film 25 Water drop 26 Solvent 27 Water vapor 41 Film manufacturing equipment 42 Solution 46-48 First to third areas 51 Casting Belt 61, 63, 64, 71 to 74 Blow suction unit

Claims (7)

A casting step of casting a solution containing an organic solvent, an amphiphilic compound having a hydrophilic group and a hydrophobic group, and a polymer compound on a support to form a cast film;
When the humidified air is sent to the cast film and the value obtained by subtracting the surface temperature TS (unit: ° C) of the cast film from the dew point TD (unit: ° C) around the cast film is ΔT, the condition of ΔT> 0 A water droplet formation / growth step in which condensation is formed on the cast film below to form water droplets, the water droplets are grown and the water droplets are disposed in the cast film,
After passing through the water droplet formation / growth step, humidified air is sent to the cast film, and array irregularity is imparted to the water droplets of the cast film under conditions of −3 ° C. <ΔT <3 ° C. Process,
A water droplet evaporation step in which the dew point TD and the temperature TS satisfy a condition of TD <TS and the water droplets are evaporated from the cast film after the arrangement irregularity imparting step. Production method.   2. The porous film according to claim 1, wherein the arrangement irregularity imparting step is performed in a range of a wind velocity V of the humidified air of 0 (m / s) <V <1.0 (m / s). Manufacturing method.   3. The water droplet formation / growth step and the arrangement irregularity imparting step make the coverage by the water droplets per unit area of the cast film within a range of 60% or more and 95% or less. A method for producing a porous film.   4. The method for producing a porous film according to claim 3, wherein in the water droplet formation / growth step and the arrangement irregularity imparting step, the diameter of the water droplet is set in a range of 0.1 μm to 100 μm. The water droplet formation / growth process includes:
A water droplet forming step of forming water droplets by condensation on the cast film under conditions of 3 ° C. ≦ ΔT ≦ 30 ° C. by blowing the humidified air;
Immediately after the water droplet formation step, the method has a water droplet growth step of growing the water droplets under the condition of 0 ° C. <ΔT ≦ 10 ° C. by blowing the humidified air and evaporating the organic solvent from the cast film. The method for producing a porous film according to any one of claims 1 to 4, wherein: The sequence irregularity imparting step is performed in a state where the viscosity of the cast film is 1 × 10 ⁻³ Pa · s or more and 1 Pa · s or less, and the time for placing the cast film is 30 seconds or more and 20 minutes or less. The method for producing a porous film according to any one of claims 1 to 5, characterized in that:   The diameter D1 of the micropores is 0.1 μm or more and 100 μm or less, the coverage per unit area of the micropores is in the range of 60% or more and 95% or less, and the center-to-center distance with the adjacent one of the micropores (Pitch) P1 varies in the range of k1 · D1 <P1 <k2 · D1 (k1 = 1.05, k2 = 4) with respect to the average diameter D1 of the fine holes, and the arrangement of the fine holes is irregular. A porous film characterized by being made.

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