JP6746910B2 - Nanofiber molded body and method for producing the same - Google Patents

Description

The present invention relates to a fine nanofiber molded article having excellent three-dimensional molding accuracy and a method for producing the nanofiber molded article.

A fibrous filler may be used for the resin composition and its molded product used as various materials in order to improve the strength.
For example, Patent Document 1 discloses a carbon fiber composite sheet in which three-dimensional random mat-like carbon fibers are impregnated with a silicone-based elastomer resin.
Attempts have also been made to mold the fibers themselves made of polymers. For example, Patent Document 2 discloses a method for producing a three-dimensional structure using polymer nanofibers by an electrospinning method, which has a predetermined three-dimensional shape with a high voltage applied between a nozzle and a collector. The target base material having the polymer nanofibers is disposed in the space between the nozzle and the collector, and the liquid polymer nanofiber raw material is discharged from the nozzle toward the collector, so that the target base material has the polymer nanofibers. A method of manufacturing a three-dimensional structure is disclosed that deposits

JP, 2007-291204, A JP, 2011-214168, A

When a three-dimensional molded body is manufactured by secondary processing of a composite sheet having a two-dimensional shape as in Patent Document 1, the number of processing steps is increased, and it is impossible to form a complicated three-dimensional shape. Further, as in Patent Document 2 described above, a technique for manufacturing a three-dimensional molded body in one step has been proposed, but the process is complicated, and thus there is a limit to improvement in productivity. Further, in the electrospinning method, the fiber diameter is limited to about 1 μm due to the clogging of the nozzle, the viscosity of the material to be extruded, and the like, and the three-dimensional molded body also had to have a certain size. For example, in Patent Document 2, a cylindrical shape having a length of 3 cm, an inner diameter of 2 mm and a thickness of 70 μm or (Patent Document 2, paragraph [0049]), a cylindrical shape having a length of 2.6 cm, an inner diameter of 1.5 mm and a thickness of 70 μm is used. It was only disclosed (Patent Document 2, paragraph [0068]).
As described above, in the prior art, it was not possible to manufacture a fine three-dimensional molded body having a maximum value of less than 1 mm among the dimensions constituting the three-dimensional shape.
Then, this invention makes it a subject to propose the novel three-dimensional molded object which is a fine three-dimensional molded object which consists of nanofibers, and has a dimension of less than 1 mm.

The present inventor, as a result of intensive studies in view of the above problems, has found that the following problems can be solved by the following methods.
That is, the present invention relates to the following [1] to [7].
[1] A three-dimensional shaped article containing 80% by mass or more of nanofibers, and the maximum diameter of the bottom surface (X-axis or Y-axis) when the maximum diameter of the article is the height (Z-axis). ) Is less than 1.0 mm, the maximum diameter height (Z axis) of the molded article is less than 1.0 mm, and either of the following (1) or (2) is satisfied. Molded body.
(1) The maximum diameter (X axis or Y axis) of the bottom surface is 20 μm or more.
(2) The cross-sectional diameter of the nanofiber is 1000 nm or less, and the aspect ratio is 120 or more.
[2] The shaped body has a pyramidal shape or a conical shape, one side of the bottom surface of the pyramid shaped body or the diameter of the bottom surface of the conical shaped body is less than 1.0 mm, and the height of the shaped body is high. Are each less than 1.0 mm and satisfy either of the following (1) or (2).
(1) One side of the bottom surface of the pyramidal shaped body or the diameter of the bottom surface of the conical shaped body is 20 μm or more.
(2) The cross-sectional diameter of the nanofiber is 1000 nm or less, and the aspect ratio is 120 or more.
[3] The molded body has a needle shape, the outer diameter of the inlet is less than 1.0 mm, and the height of the molded body is less than 1.0 mm, and either of the following (1) or (2) The nanofiber molded product according to the above [1], which satisfies the following:
(1) The outer diameter of the inlet is 20 μm or more.
(2) The cross-sectional diameter of the nanofiber is 1000 nm or less, and the aspect ratio is 120 or more.
[4] The molded body has a prismatic or cylindrical shape, one side of the bottom surface of the prismatic molded body or the diameter of the bottom surface of the cylindrical molded body is less than 1.0 mm, and the height of the molded body is high. Are each less than 1.0 mm and satisfy either of the following (1) or (2).
(1) One side of the bottom surface of the prismatic shaped body or the diameter of the bottom surface of the columnar shaped body is 20 μm or more.
(2) The cross-sectional diameter of the nanofiber is 1000 nm or less, and the aspect ratio is 120 or more.
[5] A nanofiber composite molded body having a plurality of nanofiber molded bodies according to the above [1].
[6] Molding step of molding a mold having recesses, nanofiber filling step of injecting a suspension containing nanofibers into the recesses, drying step of drying the suspension, and molding of the dried filler. A method for producing a nanofiber molded body, which has a releasing step of releasing from a mold.
[7] In the method for producing a nanofiber molded body according to the above [6], a nanofiber composite molded body is formed that simultaneously forms a plurality of nanofiber molded bodies by forming a mold having a plurality of recesses on the surface. Production method.

Since the molded product of the present invention is a three-dimensional molded product containing 80% by mass or more of nanofibers, it can have excellent physical properties such as mechanical strength.
According to the molded article of the present invention, it is possible to realize a filter that captures ultra-small molecules and a nano-level surface shape, and it is possible to provide a needle shape having a size that does not reach a pain point as an array applied to living tissue.
Further, according to the method for producing a molded product of the present invention, it is possible to mold a three-dimensional shape without performing secondary processing, so that the productivity of the nanofiber molded product can be improved.
Furthermore, the step of filling the mold having the concave portion with the suspension containing nanofibers, the step of removing the air from the filled suspension, the step of drying the filled suspension, and the molding of the dried filling material By having a step of releasing from, the molding of a fine three-dimensional shape is realized.

It is a conceptual diagram (perspective view) showing one embodiment of the nanofiber molded body of the present invention. It is a conceptual diagram (perspective view) showing one embodiment of the nanofiber molded body of the present invention. It is a conceptual diagram (cross section) which shows one Embodiment of the nanofiber molded object of this invention. It is a conceptual diagram (perspective view) showing one embodiment of the nanofiber molded body of the present invention. It is a conceptual diagram (perspective view) showing one embodiment of the nanofiber molded body of the present invention. It is a conceptual diagram (cross-sectional view) showing one embodiment of the nanofiber composite molded article of the present invention. It is a conceptual diagram (perspective view) showing one embodiment of the nanofiber composite molded body of the present invention. 1 is a digital microscope photograph of the molded body 1 obtained in Example 1. 6 is a digital microscope photograph of a molded body 2 obtained in Example 2. 5 is a digital microscope photograph of a molded body 3 obtained in Example 3. 5 is a digital microscope photograph of a molded body 4 obtained in Comparative Example 1.

Modes for carrying out the present invention will be described. However, the present invention is not limited to the embodiments described below.
The present invention is a three-dimensional shaped article containing 80% by mass or more of nanofibers, and the maximum diameter of the bottom surface (X axis or Y axis) when the maximum diameter of the article is the height (Z axis). (Axis) is less than 1.0 mm, the maximum diameter height (Z axis) of the molded body is less than 1.0 mm, and the requirement (1) or (2) below is satisfied. ..
(1) The maximum diameter (X axis or Y axis) of the bottom surface is 20 μm or more.
(2) The cross-sectional diameter of the nanofiber is 1000 nm or less, and the aspect ratio is 120 or more.

<Nanofiber molding>
The nanofiber molded product of the present invention contains 80% by mass or more of nanofibers. That is, in the present invention, it is essential that the nanofibers are contained in an amount of 80% by mass or more of the constituent material of the molded body, preferably 90% by mass or more, and more preferably 95% by mass or more, It is more preferable that the molded body is composed of only nanofibers. Therefore, when nanofibers are used as an auxiliary element for strengthening other substances, for example, molded articles and the like composed of a composition made of fiber-reinforced resin are excluded from the scope of the present invention.
Further, the nanofiber molded product of the present invention may contain a binder resin other than nanofibers, but the content of the binder resin is preferably less than 10% by mass of the constituent material of the molded product, and 5% by mass. % Is more preferable, and it is further preferable that the binder resin is not contained.
Since the nanofiber molded product of the present invention is made of nanofibers, it has excellent strength. In particular, it is preferable because it can have a strength higher than the Young's modulus of the epidermis in human skin. Therefore, as will be described later, the microneedle has a puncture property (puncture force) required when used as a microneedle, and can be effectively used.

The nanofiber molded article of the present invention has a maximum diameter of the bottom surface (X axis or Y axis) of less than 1.0 mm when the maximum diameter of the molded article is defined as height (Z axis). The maximum diameter height (Z axis) is less than 1.0 mm.
Here, the maximum diameter means the length of the longest part of the molded body, and for example, when the shape is conical and the height is the largest, the height is the maximum diameter. When the maximum diameter is taken as the height (Z axis), the maximum diameter of the bottom surface indicates the diameter of the circle that is the bottom surface.
Further, for example, in the case of a quadrangular pyramid, when the maximum diameter is set to the height (Z axis), the larger one of the X axis and the Y axis of the bottom surface becomes the maximum diameter of the bottom surface.
The nanofiber molded product of the present invention can be manufactured by further satisfying the following requirement (1). That is,
(1) The maximum diameter of the bottom surface (X axis or Y axis) is 20 μm or more.

The shape of the molded article of the present invention is not particularly limited, and can be appropriately designed according to the application and specifications. For example, as shown in the perspective view of FIG. In this case, it is important that one side of the bottom surface of the pyramidal shaped body is 20 μm or more and less than 1.0 mm, and the height of the shaped body is 20 μm or more and less than 1.0 mm. By controlling the content within this range, it is possible to obtain a molded product that effectively functions for the purposes described below. Here, the pyramid shape refers to a polygonal pyramid shape such as a triangular pyramid or a quadrangular pyramid.
Further, as shown in FIG. 2(a), it may have a conical shape. In this case, it is important that the diameter of the bottom surface of the conical shaped body is 20 μm or more and less than 1.0 mm, and the height of the shaped body is 20 μm or more and less than 1.0 mm. By controlling within this range, it is possible to obtain a molded body that effectively functions for the application described later, like the pyramidal shape.
Here, both the pyramid shape and the conical shape generally have vertices (see FIG. 1A and FIG. 2A), but in the present application, it is not always necessary to have vertices, and for example, a surface It may be (upper surface). Specifically, the shape whose sectional view is shown in FIG. 1B is also classified into a pyramid shape, and the shape whose perspective view is shown in FIG. 2B is also classified into a conical shape.

Further, as one aspect of the three-dimensional shape of the molded product made of the nanofiber of the present invention, there is a molded product having a needle shape. The needle shape in the present invention is a shape as illustrated in FIGS. 3(a) to 3(e), and the outer diameter indicating the diameter of the inlet cross section constituting the molded body is 20 μm or more and less than 1.0 mm. It is important that the height of the molded product is 20 μm or more and less than 1.0 mm. With such a shape, a molded body that effectively functions for the use described later can be obtained.

Further, the molded product of the present invention may have a prismatic shape, as shown in FIG. In this case, one side of the bottom surface of the prismatic shaped body is 20 μm or more and less than 1.0 mm, and the height of the shaped body is 20 μm or more and less than 1.0 mm. Further, the molded body of the present invention may have a columnar shape as shown in FIG. In this case, the diameter of the bottom surface of the cylindrical molded body is 20 μm or more and less than 1.0 mm, and the height of the molded body is 20 μm or more and less than 1.0 mm.

The inner surface of the nanofiber molded body of the present invention may have a hollow structure or a solid structure. In the case of a hollow structure, for example, there is an advantage that a large amount of a solution or the like can be contained inside, and in the case of a solid structure, the solution or the like can be impregnated and the strength of the nanofiber molded body can be further increased. There is an advantage that. Therefore, whether to have a hollow structure or a solid structure is appropriately determined according to the application.

The nanofiber molded product of the present invention can be manufactured by satisfying the following requirement (2). That is,
(2) The cross-sectional diameter of the nanofibers is 1000 nm or less and the aspect ratio is 120 or more.
When the requirement (2) is satisfied, the above requirement (1) does not necessarily have to be satisfied. The nanofiber will be described in detail below.

<Nanofiber>
The cross-sectional diameter (number average diameter) of the nanofibers of the present invention is preferably 1000 nm or less, more preferably 1 nm to 1000 nm, further preferably 1 to 500 nm, and further preferably 2 to 100 nm. Particularly preferred. When the cross-sectional diameter (number average diameter) of the nanofibers is within the above range, the following aspect ratio is satisfied, and handling properties during molding and penetrability during use are improved. In particular, the higher the aspect ratio, the better the releasability and transferability during molding, which is preferable. Therefore, it is preferable to use nanofibers having a larger aspect ratio as the shape to be molded is finer.
When the nanofiber has a non-circular cross section, the term cross-sectional diameter (number average diameter) as used in this specification refers to the maximum cross-sectional dimension.

The length of the nanofibers is preferably 0.1 to 2000 μm, more preferably 0.1 to 1000 μm for the reason of moldability.
Further, the nanofiber used in the present invention preferably has an aspect ratio of 20 or more, more preferably 80 or more, particularly preferably 100 or more, further 120 or more, 200 or more because it can withstand the peeling force at the time of release. Is more preferable, and 300 or more is extremely preferable. As described above as the requirement (2), the nanofiber molded article of the present invention has a nanofiber aspect ratio of 120 or more, even if the nanofiber of the present invention does not satisfy the requirement (1). Can be molded. Further, it is preferable that both the requirement (1) and the requirement (2) are satisfied from the viewpoint of handling property at the time of molding (releasability and transferability at the time of molding), permeability at the time of use, and the like.
On the other hand, from the viewpoint of maintaining the strength in the height direction of the molded body, the aspect ratio is preferably 10,000 or less, more preferably 3000 or less, and particularly preferably 1000 or less.

Further, as described above, the nanofiber molded body of the present invention is preferably a molded body composed only of nanofibers containing no binder resin or the like. Therefore, the nanofiber used in the present invention is preferably composed of a water-insoluble substance because it can be easily molded with only the fiber. Examples of the water-insoluble substance include cellulose, polylactic acid, carbon, and ceramics.

Furthermore, the nanofibers are preferably biocompatible substances. By using a biocompatible substance, even if a damaged molded body remains in the body, it does not adversely affect the human body. Examples of such materials include inorganic compounds such as Mg compounds and Ti compounds; polysaccharides such as chitin, chitosan, cellulose and hyaluronic acid; other biopolymer compounds such as maltose and dextran; polylactic acid and polyglycol. Examples thereof include synthetic organic polymer compounds such as acids, polylactic acid glycolic acid copolymers, polycitric acid, and polymalic acid. Alumina fibers (alumina nanofibers) are also preferably used, and some of the alumina are also biocompatible substances.
As described above, the nanofiber used in the present invention is more preferably a water-insoluble substance and a biocompatible substance. Nanofibers, which are water-insoluble substances and biocompatible substances, include, for example, cellulose, polylactic acid, some chitins, chitosans, and alumina fibers.
These nanofibers can be appropriately selected depending on the application. For example, alumina nanofibers are two-dimensionally or three-dimensionally oriented by self-assembly by drying, so that a formed product of the nanofibers can be formed. When it is used for microneedles with improved barrier properties, it is particularly preferable because it has advantages such as an antioxidation effect of a drug solution and an increased puncture strength in the depth direction.

In the nanofiber molded body of the present invention, it is preferable that the sectional thickness T ¹ near the bottom surface and the sectional thickness T ² near the apex have a relationship of T ¹ ≦T ² . With such a structure, the strength of the tip can be improved. In order to obtain the above relationship of T ¹ ≦T ² , it can be achieved by dispensing a suspension containing nanofibers described below and repeating the steps of filling and drying.
Here, the vicinity of the bottom surface means an area from the bottom surface to 10% of the height with respect to the height of the nanofiber molded body, and the vicinity of the apex means an area from the apex to 10% of the height. Further, the apex means the apex when the nanofiber molded body has a pyramidal shape, a conical shape, or the like, but when the apex does not exist and forms a surface, as described above, Refers to the upper surface.

<Nanofiber composite molded body>
The nanofiber composite molded body of the present invention has a plurality of the above nanofiber molded bodies. The schematic view (cross-sectional view) is illustrated in FIGS. A sheet-shaped composite molded body can be preferably used as a microneedle patch. For example, as shown in the perspective view of FIG. 7, a disk-shaped microneedle patch in which a nanofiber molded body is provided in a circular shape. Are exemplified.

<Manufacturing method of nanofiber molded body>
The method for producing a nanofiber molded body of the present invention includes a molding step, a nanofiber filling step, a drying step, and a mold releasing step.

(Molding process)
The mold forming step in the present invention is a step of forming a mold having a recess. The mold used for producing the nanofiber molded product of the present invention may be of various types, regardless of its shape, material, etc., but in the releasing step described later, the transfer of the nanofiber molded product of the present invention is performed. From the viewpoint of improving the property, it is desirable that the base material of the mold has a shape and material that has a smooth surface and easily releases the filling substance. Therefore, the shape of the mold base material is preferably a flat surface, a plate shape such as a curved plate shape, or a disk shape, and a shape having a smooth surface. The material of the mold base material includes resins and metals, but polyolefin resins, fluorine resins, silicone resins and the like are preferable, and silicone resins are particularly preferable.

In the present invention, it is essential to form a recess for obtaining the desired shape of the nanofiber molded body, and the shape is the same as the above-mentioned nanofiber molded body of the present invention. That is, it is preferable to form a recess having an outer diameter of less than 1.0 mm, a depth of less than 1.0 mm, and an outer diameter of 20 μm or more. Details will be described later.
As a specific method of forming the concave portion, a concave portion that matches the shape of the target nanofiber molded body is formed on the mold base material by using a method such as mechanical processing or laser processing. In particular, a method of cutting a plate-shaped base material made of a silicone resin by the above-mentioned method or the like is preferable in terms of easiness of processing.
Further, depending on the shape of the concave portion, it is possible to manufacture it by a photolithography method. For example, when a needle shape is manufactured, it can be manufactured by the MEMS (Micro Electro Mechanical Systems) technology described below. More specifically, the following method is used.
(A) An etching mask material such as a silicon oxide film is formed on the surface of a Si substrate, which is a base material. The thickness of the silicon oxide film is determined from the alkaline aqueous solution species used in the etching process, the temperature, and the etching amount.
(B) The mask pattern shape is transferred to the mask material by the photolithography technique. For example, a photosensitive resin is applied to the surface of the Si substrate, and the mask pattern is transferred to the photosensitive resin using ultraviolet rays. The silicon oxide film is etched with a hydrofluoric acid buffer solution based on the photosensitive resin pattern, and the mask patterning is transferred to the silicon oxide film as an etching mask material.
(C) A Si mold is created by selectively removing the Si substrate with an alkaline aqueous solution based on the etching mask pattern formed on the surface of the Si substrate.
Although crystal anisotropic etching is used in the above case, molds of various shapes can be produced by changing the plane orientation of the single crystal substrate and the shape of the etching mask.

The shape of the recess is the same as the three-dimensional shape of the target nanofiber molded body, and examples thereof include a polygonal pyramid such as a cone and a triangular pyramid, a cylinder, and a polygonal prism such as a triangular prism. The inlet shape of the recess may be rectangular or circular, and the outlet shape of the recess may be, for example, a shape with a sharp tip such as a columnar shape or a prismatic shape. It doesn't have to be. Further, the three-dimensional shape formed by the recess may be a shape in which two or more solids are combined, such as a shape in which a cone is stacked on a cylinder.

Further, the three-dimensional shape of the recess may have a hole at the tip. In order to improve transferability and releasability of the molded body described later, the three-dimensional shape of the recess is a shape that penetrates through the mold, and the outer diameter of the outlet is smaller than the outer diameter of the inlet. Those having a shape are preferable.
From the viewpoint of releasability, the outer diameter of the inlet of the recess of the mold needs to be 20 μm or more, more preferably 30 μm or more, and particularly preferably 40 μm or more. Further, the outlet diameter is 0 in the case where the recess of the mold does not penetrate. From the viewpoint of venting air, which will be described later, the outlet diameter is preferably 1 to 100 μm.

Further, by providing a plurality of recesses on the smooth surface of the mold base material, the nanofiber molded product of the present invention can be efficiently obtained. The three-dimensional shape formed by the plurality of recesses may be regularly arranged on one surface of the mold substrate or may be irregularly arranged. Further, the three-dimensional shape formed by the plurality of recesses may be arranged at a plurality of locations on one plane of the mold base material in a biased manner, and for example, may be arranged in a grid or concentric circles.
The mold used in the present invention can be further subjected to a sterilization treatment, a sterilization treatment and the like. As a result, it can be effectively used as an application requiring biocompatibility, such as pharmaceutical preparations and cosmetics.

(Nanofiber filling process)
The nanofiber filling step is a step of injecting a suspension containing nanofibers into the recesses obtained by the molding step. Here, the suspension containing nanofibers is not particularly limited as long as it contains the above-mentioned nanofibers, and a commercially available suspension may be used.
Since the suspension is filled in the mold and then dried, it is preferable that the nanofibers be diluted with a highly volatile solvent. The solvent used is not particularly limited, but may be water, an aqueous acid solution, an aqueous base solution, or the like. Particularly, water is preferable because of environmental consideration and skin irritation when it remains after drying. Further, the content of nanofibers in the suspension is preferably 50% by mass or less, more preferably 10% by mass or less, and particularly preferably 5% by mass or less, for the reason of transferability. On the other hand, from the viewpoint of moldability, it is preferably 0.1% by mass or more, more preferably 0.5% by mass or more.

The suspension containing the nanofibers is poured into the mold having the concave portions in the shape of the nanofiber molded body, which is manufactured as described above. At this time, it is preferable to evacuate air from the inside of the concave portion of the mold in order to fill the suspension up to the tip of the concave portion.
From the viewpoint of effectively bleeding air from the inside of the concave portion of the mold, the concave portion of the mold preferably has a penetrating shape with an outlet diameter of 1 to 100 μm.
The method of removing air is not particularly limited, and examples thereof include an air pressing method from the upper surface of the concave portion of the mold, a depressurizing method from the lower surface of the concave portion of the mold, and a method of using centrifugal force. At this time, from the viewpoint of effectively bleeding air, it is preferable that the outer diameter of the outlet of the three-dimensional shape formed in the concave portion of the mold is processed to be smaller than the outer diameter of the inlet. Thereby, the suspension can be prevented from flowing out from the outlet side of the mold recess, and only the air can be effectively removed.

Further, it is preferable that the suspension containing the nanofibers is dispensed at once and poured into a plurality of times in a divided manner. When dispensing, it is preferable to repeat the filling step and the suspension drying step described below twice or more.
By such dispensing, it is possible to increase the thickness and strength of the nanofiber molded body, prevent mold release defects, and improve transfer moldability and productivity.

In particular, when the molded body of the present invention has a pyramidal shape, a conical shape, and a needle shape, the suspension is dispensed, and the molded body is filled with a plurality of times and dried, as described above. The relationship between the cross-sectional thickness T ¹ near the bottom surface and the cross-sectional thickness T ² near the apex is T ¹ ≦T ² , and the strength of the tip can be improved.
Further, it is preferable to have a step of placing the adherend on the surface of the suspension after the suspension is filled and before the drying step. According to this, since the adherend is integrated with the nanofibers, it is possible to improve the transferability of the nanofiber molded body in the releasing step described later. When the filling step or the drying step is repeated twice or more, it is preferable to have a step of placing the adherend before the final drying step.
The adherend is not particularly limited in shape, material, etc., and is appropriately determined depending on the application, and examples thereof include tape, plate material, gauze and the like.

(Drying process)
The drying step is not limited as long as it volatilizes the solvent component contained in the nanofiber suspension, and a known drying method can be adopted. For example, there are methods such as an oven (hot air dryer) and natural drying (no wind, normal temperature).
At this time, it is preferable to dry at a temperature of 80° C. or lower for the reason of improving the production efficiency and being applicable to a molded body that requires molding at a low temperature. More specifically, the temperature is preferably 20 to 80°C, more preferably 20 to 50°C.
The drying time is appropriately adjusted according to the size and shape of the nanofiber molded product, and usually about 5 seconds to 20 minutes is preferable.

In the method for producing a nanofiber molded body of the present invention, since it is not necessary to perform high-temperature treatment conventionally performed by etching with a chemical agent or using a resin, as described above, only the low-temperature treatment for volatilizing the solvent is performed. A molded product can be obtained through.
When the steps from filling to drying are repeated a plurality of times, in the final drying step, the releasability can be enhanced by setting the drying time sufficiently long.

(Release process)
After completing the filling process or the drying process, the nanofiber molded body, which is the dried filling material, is released from the concave portion of the mold. At this time, the nanofiber molded body is released at a speed and strength at which it is not destroyed.
The nanofiber molded product of the present invention may be subjected to a cutting process, a through-hole forming process, or the like after the releasing step in order to obtain a desired three-dimensional shape.

<Method of manufacturing nanofiber composite molded body>
A nanofiber composite molded body can be manufactured using the method for manufacturing a nanofiber molded body described above. That is, a nanofiber composite molded body having a plurality of nanofiber molded bodies of the present invention can be formed by forming a plurality of concave portions on one surface of the mold base material. Here, by forming the concave portion into an inverted conical shape such as a needle shape, a molded body in which a plurality of needle shapes are arranged, such as a microneedle patch, can be obtained.
In particular, by forming a nanofiber composite molded body in which a plurality of recesses are regularly arranged, the nanofiber composite molded body can be used as it is as a microneedle patch, so that the productivity is extremely high. That is, the nanofiber composite molded body of the present invention is effective as a microneedle patch.

<Applications of nanofiber moldings>
The nanofiber molded body of the present invention can be used for various purposes as a molded body alone or as a composite having a plurality of molded bodies.
Among them, the nanofiber molded body of the present invention is needle-shaped, and when applied to a microneedle patch consisting of a plurality of molded bodies, the nanofiber molded body of the present invention has excellent physical properties such as strength. , Preferably used.

When the molded product of the nanofiber of the present invention is used as a microneedle patch, a through hole may be formed inside the microneedle or in the vicinity of the microneedle. By providing the through-hole, it can be suitably used for a device having a structure for collecting/supplying a body fluid/medicine solution through the through-hole.
For example, when using microneedles for the purpose of transdermal administration, it is desirable that the cross-sectional diameter (number average diameter) of the through-hole be several μm to several hundreds μm and the length be several tens to several hundreds μm. .. Furthermore, the nanofiber molded product of the present invention is preferably a composite of molded products formed in a hollow shape from the viewpoint of enhancing the liquid-feeding property of the medicinal component and increasing the liquid-feeding amount.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples without departing from the scope of the invention. The various measurements and evaluations in the examples were carried out by the following methods.

<Transferability>
Using a digital microscope (“VHX-600” manufactured by KEYENCE), the shape of each product (sample) after mold release was evaluated as follows.
◯: A shape similar to the shape of the concave portion of the mold was transferred.
X: The tip was broken or the nanofibers were projected, so that a shape greatly different from the ridgeline of the concave portion of the mold was formed.

Example 1
(1) Molding A flat sheet base material made of silicone resin was fixed with a double-sided tape. The double-sided tape was attached to the side opposite to the processed surface on which the recess was formed. Next, using a high-speed universal AI CNC drill (machining center) "Robodrill α-T14iFa" manufactured by FANUC, recesses were formed in the flat surface portion of the sheet base material fixed under the following conditions.
Cutting conditions: Chamfer drill SVMA030-090
Operating conditions: rotation speed 10000 rpm, cutting feed rate 5 mm/min, holding pressure 3,000 sec,
Recessed shape: conical (tapered) with through holes. The entrance diameter (the diameter of the bottom of the cone) is 800 μm, the exit diameter of the through hole is 10 μm, and the depth of the recess is 300 μm.
A total of 25 recesses 5×5 in length and width were formed on the same plane of one sheet base material.

(2) Filling of nanofibers and drying of suspension As a suspension containing nanofibers, "BiNFi-s Sfo-20002" manufactured by SUGINO Machine Limited (chitin: diameter 2 to 20 nm, aspect ratio: 100, long) About 5 μm, 2.2 wt%, viscosity: 3040 mPa·s, solvent: water).
The recess of the mold was filled with the suspension. The suspension was divided into four portions, dispensed, and each time it was filled once, the step of removing air and the step of drying were performed, and the next filling was performed again.
The step of removing air was performed by depressurizing the bottom so that the suspension completely filled the outlet of the recess. In addition, in the step of drying the suspension after removing the air, using a hot air dryer, the first to third drying conditions are 40° C. for 15 seconds, and the last one is performed at 40° C. for 15 minutes. The suspension was dried completely.

(3) Demolding After completion of the filling step or the drying step, the nanofiber molded body formed in the recess is demolded from the mold at a speed that does not destroy it, and 25 molded bodies 1 (5×5 in length and width) are formed in a composite molding. Got the body The molded body 1 was a molded body having a hollow structure having a bottom surface shape equivalent to the inlet shape of the concave portion of the mold and an upper surface shape equivalent to the outlet shape of the concave portion of the mold. FIG. 8 shows a digital microscope photograph.

Example 2
(1) Molding In Example 1, instead of the high-speed universal AI CNC drill, a picosecond laser processing machine (“DUETTINO” manufactured by Time-Bandwidth Co.) was used to form the recesses. Similarly, a mold having a recess was formed. Specifically, the flat portion of the sheet substrate was irradiated with a picosecond laser at a pulse energy of 100 μJ for 0.5 second to form a recess in the flat portion of the sheet base material.
Recessed shape: conical (tapered) with through holes. The entrance diameter (the diameter of the bottom of the cone) is 40 μm, the exit diameter of the through hole is 20 μm, and the depth of the recess is 300 μm.
A total of 25 recesses 5×5 in length and width were formed on the same plane of one sheet base material.
(2) Filling of nanofibers and drying of suspension As a suspension containing nanofibers, "F-1000" manufactured by Kawaken Fine Chemicals Co., Ltd. (alumina nanofiber: diameter 4 nm, length 1400 nm, aspect ratio 350, concentration) The nanofibers were filled and the suspension was dried in the same manner as in Example 1 except that 4.5 to 5 wt%, viscosity: 10 to 500 mPa·s, solvent: water) were used.
(3) Demolding In the same manner as in Example 1, a composite molded body including 25 molded bodies 2 (5×5 in length and width) was obtained. The molded body 2 was a molded body having a hollow structure having a bottom surface shape equivalent to the inlet shape of the concave portion of the mold and an upper surface shape equivalent to the outlet shape of the concave portion of the mold. FIG. 9 shows a digital microscope photograph.

Example 3
(1) Molding In the same manner as in Example 2, a recess was formed in the flat surface portion of the sheet base material.
Recessed shape: conical (tapered) with through holes. The entrance diameter (the diameter of the bottom of the cone) is 100 μm, the exit diameter of the through hole is 40 μm, and the depth of the recess is 100 μm.
A total of 9 recesses were formed in the same plane of one sheet base material, 3×3 in length and width.
(2) Filling of Nanofibers and Drying of Suspensions As a suspension containing nanofibers, "15B06CNF-1BBB" (viscosity: 605cPa, solvent: water) manufactured by Chuetsu Pulp Co., Ltd. was used. In the same manner as in 1, filling of nanofibers and drying of the suspension were performed.
(3) Releasing In the same manner as in Example 1, a composite molded body having 9 molded bodies 3 (3×3 in length and width) was obtained. The molded body 3 was a molded body having a hollow structure having a bottom surface shape equivalent to the entrance shape of the recess of the mold and an upper surface shape equivalent to the exit shape of the recess of the mold. FIG. 10 shows a digital microscope photograph.

Comparative Example 1
In Example 1, the same as in Example 1 except that the inlet diameter of the recess (the diameter of the bottom surface of the cone) was 15 μm and the outlet diameter of the through hole was 9 μm (the recess depth is 300 μm and Similarly, a (sample) of the molded body 4 was prepared, but the tip was broken or partly broken during releasing, and the transferability was insufficient. FIG. 11 shows an electron micrograph.
The height of the molded body 4 was 55 μm, and it can be seen that the tip was broken during the mold release.

According to the present invention, a fine molded body made of nanofibers can be obtained.
Further, since the molded product of the present invention has a fine three-dimensional shape and is excellent in transferability, it can be used for a filter that captures ultra-small molecules, a biological tissue having a nano-level surface shape, or the like. It can be applied to various industries such as healthcare, environment, energy, etc.
According to the manufacturing method of the present invention, it is possible to mold a three-dimensional shape without secondary processing, and it is possible to improve the productivity of the nanofiber molded body.

Claims (18)

A three-dimensional shaped article containing 80% by mass or more of nanofibers, wherein the nanofibers are alumina fibers, and the maximum diameter of the article is the maximum diameter of the bottom surface (Z axis). (X axis or Y axis) is less than 1.0 mm, the maximum diameter height (Z axis) of the molded product is less than 1.0 mm, and either (1) or (2) below is satisfied. Nanofiber molded product characterized by:
(1) The maximum diameter (X axis or Y axis) of the bottom surface is 20 μm or more.
(2) The cross-sectional diameter of the nanofiber is 1000 nm or less, and the aspect ratio is 120 or more. The shaped body has a pyramidal shape or a conical shape, one side of the bottom surface of the pyramid shaped shaped body or the diameter of the bottom surface of the conical shaped body is less than 1.0 mm, and the height of the shaped body is The nanofiber molded product according to claim 1, wherein the nanofiber molded product has a diameter of less than 1.0 mm and satisfies either of the following (1) or (2).
(1) One side of the bottom surface of the pyramidal shaped body or the diameter of the bottom surface of the conical shaped body is 20 μm or more.
(2) The cross-sectional diameter of the nanofiber is 1000 nm or less, and the aspect ratio is 120 or more. The molded body has a needle shape, the outer diameter of the inlet is less than 1.0 mm, the height of the molded body is less than 1.0 mm, and either (1) or (2) below is satisfied. The nanofiber molded body according to claim 1.
(1) The outer diameter of the inlet is 20 μm or more.
(2) The cross-sectional diameter of the nanofiber is 1000 nm or less, and the aspect ratio is 120 or more. The shaped body has a prismatic shape or a cylindrical shape, one side of the bottom surface of the prismatic shaped body or the diameter of the bottom surface of the cylindrical shaped body is less than 1.0 mm, and the height of the shaped body is The nanofiber molded product according to claim 1, wherein the nanofiber molded product has a diameter of less than 1.0 mm and satisfies either of the following (1) or (2).
(1) One side of the bottom surface of the prismatic shaped body or the diameter of the bottom surface of the columnar shaped body is 20 μm or more.
(2) The cross-sectional diameter of the nanofiber is 1000 nm or less, and the aspect ratio is 120 or more. Nanofibers molded article according to any one of claims 1 to 4 which is a hollow structure. Nanofiber composite molding having a plurality of nanofibers molded body according to any one of claims 1-5. A microneedle patch comprising the nanofiber composite molded body according to claim 6 . Molding step of molding a mold having a concave portion, nanofiber filling step of injecting a suspension containing nanofibers into the concave portion, drying step of drying the suspension, releasing the dried filling from the mold The method for producing a nanofiber molded article, which comprises a release step of: The method for producing a nanofiber molded article according to claim 8 , wherein the recess has an outer diameter of 20 μm or more and less than 1.0 mm and a depth of 20 μm or more and less than 1.0 mm. The method for producing a nanofiber molded article according to claim 8 or 9 , wherein the nanofiber has a cross-sectional diameter of 1000 nm or less and an aspect ratio of 120 or more. In the filling step, the suspension containing the nanofibers is dispensed, and the filling step and the drying step are repeated twice or more, to manufacture the nanofiber molded article according to any one of claims 8 to 10. Method. When the concave portion of the mold has a shape that penetrates through the mold and the inlet side of the concave portion is the inlet side of the suspension and the outlet side is opposite to the inlet, the outlet diameter of the concave portion is The method for producing a nanofiber molded body according to any one of claims 8 to 11 , wherein the diameter is smaller than the inlet diameter and the outlet diameter of the recess is 1 to 100 µm. In the filling step, air is evacuated from inside the concave portion of the mold using at least one method selected from an air pressing method from the upper surface of the concave portion of the mold, a depressurizing method from the lower surface of the concave portion of the mold, and a method using centrifugal force. The method for producing the nanofiber molded body according to claim 12 . The drying step the method for producing nanofibers molded body according to any one of claims 8 to 13 carried out at 80 ° C. or lower. The method for producing a nanofiber molded article according to any one of claims 8 to 14 , wherein in the molding step, a recess is formed by cutting a plate-shaped base material made of a silicone resin. The method for producing a nanofiber molded body according to any one of claims 8 to 15 , comprising a step of placing an adherend between the filling step and the drying step. The method for producing a nanofiber molded body according to any one of claims 8 to 16 , wherein a mold having a plurality of recesses is formed on the surface to simultaneously form a plurality of nanofiber molded bodies. Method for producing molded body. 18. The nano according to claim 17 , wherein the recess has an inverted pyramid shape, an inverted cone shape, or a needle shape in which the side on which the suspension is injected is the upper surface of the recess and the opposite side is the vertex of the recess. A method for producing a fiber composite molded body.