JP6651757B2 - Composite and method for producing the same - Google Patents

Description

  The present invention relates to a composite including a porous fibroin body and a nonwoven fabric made of thermoplastic resin fibers, and a method for producing the same.

Porous materials that can be produced using biological substances such as proteins and saccharides are used in cosmetics and esthetic fields for the purpose of moisturizing and the like by use in an aesthetic salon or an individual, and also a wound dressing material, Support for cell culture support (scaffolding material) and tissue regeneration support in microbiological fields such as medical sustained-release carriers, disposable diapers, sanitary products, etc., tissue engineering, regenerative medicine engineering, etc. It is also expected to be applied in a wide range of industrial fields, such as the water purification field that can be used as a body.
As a biological substance constituting these porous bodies, saccharides such as cellulose and chitin, and proteins such as collagen, keratin, and silk fibroin are known.

Among these biological materials, collagen has been used most as a protein, but it has become very difficult to use bovine collagen after the occurrence of the BSE problem. Keratin can be obtained from wool, feathers, etc., but has problems in stable supply of raw materials and in price, and is difficult to industrially use. On the other hand, silk fibroin can be expected to be supplied stably from the viewpoint of obtaining raw materials, and its price is also stable, so that it can be easily used industrially.
In addition, silk fibroin has a long track record of being used as a surgical suture in addition to clothing, and is currently used as an additive in foods and cosmetics. It is sufficiently applicable to the fields of use of the porous body as described above.

There are several reports on the method of producing a silk fibroin porous material. For example, a method has been proposed in which a silk fibroin aqueous solution is rapidly frozen, then immersed in a crystallization solvent, and melting and crystallization proceed simultaneously to produce a porous fibroin body (Patent Document 1). However, this method requires the use of a large amount of an organic solvent as a crystallization solvent, and furthermore, the possibility that the solvent remains cannot be denied, and there is a problem in use in the above-mentioned application fields such as the medical field.
Also, a method for producing a porous silk fibroin body in which the pH of an aqueous solution of silk fibroin is maintained at 6 or less to cause gelation or the aqueous solution is gelled by adding a large amount of a poor solvent, and the obtained gel is freeze-dried. Has been proposed (Patent Document 2). However, since a solvent is used, there is a problem similar to that of Patent Document 1, and the porous body obtained by this method does not have sufficient strength.
Furthermore, there has been proposed a method of producing a porous silk fibroin body by maintaining a frozen state for a long time after freezing an aqueous solution of silk fibroin (Patent Document 3). However, when the present inventors performed additional testing of the method described in Patent Document 3, it was considered that a porous body was not obtained, and there was a problem in reproducibility.

On the other hand, there has been reported a method for reliably and easily obtaining a high-strength porous silk fibroin body in comparison with the above-described method for producing a porous silk fibroin body (Patent Document 4 and Non-Patent Document 1). Patent Literature 4 and Non-Patent Literature 1 have a high water content and a high mechanical strength by adding a small amount of a water-soluble organic solvent to an aqueous solution of silk fibroin, followed by freezing for a certain period of time, followed by thawing. It is disclosed that an excellent hydrogel can be produced.
Further, in Patent Document 5, after adding a small amount of an aliphatic carboxylic acid to an aqueous solution of silk fibroin, freezing for a certain period of time, and then thawing, the method described in Patent Document 4 and Non-patent Document 1 is further improved. A production method for obtaining a high-strength porous silk fibroin body has been proposed.

JP-A-8-41097 Japanese Patent Publication No. 6-94518 JP 2006-249115 A Japanese Patent No. 3412014 International Publication No. 2010/116994

Biomacromolecules, 6, 3100-3106 (2005)

Skin care materials such as face masks, eye masks, etc., which are required to be easy to handle in a thin state, wound dressing materials that are expected to be applied to the human body, such as fingers and knees, handling and embedding during cell culture In applications such as scaffold materials for regenerative medicine that require strength after planting, even a porous body produced by the production method described in Patent Document 5 has insufficient strength.
As a method for improving the strength of the porous body, there is also a method for improving the strength of the silk fibroin porous body itself.However, according to this method, the structure and texture of the silk fibroin are often changed, and According to the study of the present inventors, it has been found that there is a problem that a dramatic improvement in strength cannot be expected even by this method.

  Therefore, in the present invention, a fibroin porous body having excellent mechanical strength such as tearing strength and adhesive force between members constituting a composite without impairing the advantages of texture such as softness and softness of the fibroin porous body. An object of the present invention is to provide a composite containing the same and a method for producing the same.

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that the object can be solved by the following invention.
That is, the present invention provides the following [1] to [7].
[1] A composite comprising a porous fibroin body and a non-woven fabric made of thermoplastic resin fibers, wherein the porous body and the non-woven fabric are joined by a thermoplastic resin constituting the thermoplastic resin fibers. body.
[2] The composite according to the above [1], wherein the thermoplastic resin is a polyurethane.
[3] The composite of the above-mentioned [1] or [2], wherein the basis weight of the nonwoven fabric constituted by the thermoplastic resin fibers is 10 to 100 g / m ² .
[4] The composite according to any one of [1] to [3], wherein the thermoplastic resin fiber has a fiber diameter of 1 to 50 μm.
[5] The complex according to any one of [1] to [4], wherein the porous fibroin body contains glycerin.
[6] The method for producing a composite according to any one of [1] to [5], wherein thermoplastic resin fibers fibrillated by a melt spinning method are accumulated on a fibroin porous body, A method for producing a composite, comprising forming a nonwoven fabric composed of the thermoplastic resin fibers on a substrate.
[7] The method for producing a composite according to the above [6], wherein the melt spinning method is a melt blow method.

  ADVANTAGE OF THE INVENTION According to this invention, the fibroin porous body which is excellent in the mechanical strength, such as tearing strength, and the adhesive force between the members which comprise a composite body, without impairing the merit of the texture, such as softness and softness of a fibroin porous body. And a method for producing the same.

It is a schematic diagram which shows the cross-section of the composite of this invention. 4 is an infrared spectrum of the silk fibroin porous material used in Example 1. It is a mimetic diagram showing a manufacturing method of a composite by a melt blow device. 3 is a scanning electron micrograph of a cross-sectional structure of the composite manufactured in Example 1.

[Composite]
The composite of the present invention includes a fibroin porous body and a non-woven fabric made of thermoplastic resin fibers, and the porous body and the non-woven fabric are joined by a thermoplastic resin constituting the thermoplastic resin fibers. Complex.
In addition, in this specification, a fibroin porous body may be simply called a "porous body." In addition, a nonwoven fabric composed of thermoplastic resin fibers may be referred to as a “thermoplastic nonwoven fabric”.

FIG. 1 is a schematic diagram showing an example of the structure of the composite of the present invention, and shows a composite 10 in which a thermoplastic resin nonwoven fabric 11 and a fibroin porous body 12 are joined.
In the composite 10, a part of the thermoplastic resin fiber constituting the thermoplastic resin nonwoven fabric 11 is melted and joined to the fibroin porous body 12.
That is, the composite of the present invention is a thermoplastic resin in which the porous layer and the thermoplastic nonwoven fabric are one of the layers constituting the composite without using a separate adhesive. Thus, the use of different materials can be reduced, and excellent bonding strength can be obtained without impairing the advantages of the excellent fibrin porous material such as excellent flexibility and texture.
Further, the composite of the present invention, by applying a thermoplastic resin nonwoven fabric as a reinforcing layer of the fibroin porous body, while securing superior flexibility than a composite using a known film material or the like as the reinforcing layer. Further, it can be suitably used in applications requiring performance such as air permeability and water permeability.

<Fibroin porous material>
The fibroin porous body is not particularly limited as long as it is a porous body composed of fibroin.
The fibroin porous body may be produced by any known method, but in consideration of mechanical strength, texture, reproducibility during production, etc., a small amount of a water-soluble organic solvent and It is preferable to prepare by a technique of adding at least one selected from acids, freezing for a certain period of time, and then thawing.
In this specification, at least one selected from the group consisting of the water-soluble organic solvent and the aliphatic carboxylic acid may be referred to as an “additive”.

  Examples of the fibroin used for the fibroin porous body include natural silkworms such as domestic silkworms, wild silkworms, and natural silkworms, and silk fibroin produced from transgenic silkworms and the like, and the production method thereof is not particularly limited. Among these, those produced from silkworm cocoons are particularly preferred in view of the simplicity of the production process.

Hereinafter, silk fibroin, which is preferable as fibroin, will be described as an example.
There is no particular limitation on the method of dissolving silk fibroin in water.For example, since silk fibroin has low solubility in water, after dissolving silk fibroin in a high-concentration aqueous solution of lithium bromide, desalting by dialysis is performed. The method of obtaining is suitably mentioned. As a method for adjusting the concentration of silk fibroin in the aqueous solution of silk fibroin, a method involving concentration by air drying is simple and preferable.

  The concentration of silk fibroin in the aqueous solution of silk fibroin is preferably 0.5 to 40 wt / vol%, more preferably 1 to 20 wt / vol%, More preferably, it is 10 wt / vol%. When the concentration of silk fibroin is within the above range, a porous body having an excellent texture tends to be obtained.

There is no particular limitation on the water-soluble organic solvent to be added as an additive, but it is preferable to use one having excellent safety for the human body. Specific examples include ethanol, acetone, dimethyl sulfoxide and the like.
The aliphatic carboxylic acids to be added as additives are not particularly limited as long as they are organic acids having at least one carboxy group in the molecule, and include, for example, monocarboxylic acids, dicarboxylic acids, and tricarboxylic acids.
Further, as the aliphatic carboxylic acids, aliphatic carboxylic acids having 1 to 6 carbon atoms are preferable, and aliphatic carboxylic acids having 2 to 5 carbon atoms are more preferable. These aliphatic carboxylic acids may be saturated aliphatic carboxylic acids or unsaturated aliphatic carboxylic acids.
Specific examples of such aliphatic carboxylic acids include monocarboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, lactic acid, acrylic acid, and 2-butenoic acid; oxalic acid, malonic acid, succinic acid, and maleic acid. Dicarboxylic acid and the like are preferred, and acetic acid, lactic acid, and succinic acid are more preferred in consideration of safety to the human body. These additives can be used alone or in combination of two or more.

  The content of the additive in the aqueous silk fibroin solution is preferably 0.01 to 18% by volume, more preferably 0.1 to 5% by volume, and 0.5 to 3% by volume. Is more preferred. When the content of the additive is within the above range, the solution does not gel, and a silk fibroin porous material having sufficient strength tends to be produced.

The freezing of the aqueous solution of silk fibroin is preferably performed by pouring a solution obtained by adding an additive to the aqueous solution of silk fibroin into a mold or a container, and placing the container in a liquid-cooled low-temperature constant temperature bath.
The freezing temperature is not particularly limited as long as the silk fibroin aqueous solution to which the additive is added is frozen, but is preferably about -1 to -40 ° C, more preferably about -5 to -40 ° C, and -10 to- 30 ° C. is more preferred. The freezing time is preferably 2 hours or more, more preferably 4 hours or more, so that the aqueous solution of silk fibroin to which the additive has been added is sufficiently frozen and the frozen state can be maintained for a certain time. In the freezing step, it is preferable to maintain the temperature at -10 to -30C for 30 minutes to 100 hours in order to form the porous body with good reproducibility.

  Here, the aqueous solution of silk fibroin to which the additive has been added may be frozen at a stretch by lowering to a freezing temperature. preferable. For example, the silk fibroin aqueous solution to which the additive is added is temporarily held at about −2 to −10 ° C. for about 1 to 5 hours, and then is cooled to the above-mentioned freezing temperature and frozen, so that the silk fibroin porous material having a uniform structure is obtained. Can be obtained.

  After the silk fibroin aqueous solution is frozen by the above method, the frozen silk fibroin aqueous solution is thawed to obtain a silk fibroin porous body. The melting method is not particularly limited, and includes spontaneous melting and storage in a thermostat.

  The additive remains in the porous silk fibroin obtained as described above. The remaining additives may be left as they are or may be removed depending on the application. As a method for removing the additive from the porous silk fibroin, for example, a simple method of immersing the porous silk fibroin in pure water to remove the additive can be mentioned.

The silk fibroin porous body thus obtained is in a state of absorbing water. In the case where use of the dried silk fibroin porous body is required in the production method of the present invention, the above-mentioned water-absorbed silk fibroin porous body may be dried.
The method for drying the silk fibroin porous body is not particularly limited, but lyophilization is preferred from the viewpoint of suppressing shrinkage. In the case of freeze drying, if the drying is completed without completely sublimating the water, the remaining ice melts and turns into water, and the pores are crushed by the effect of the surface tension. Drying is preferred.
The dried silk fibroin porous body (hereinafter also referred to as “dried silk fibroin porous body”) dried as described above does not substantially contain moisture. Since the silk fibroin porous body is obtained by freezing and thawing an aqueous solution of silk fibroin, it is usually in a state where moisture or the like is present in the pores. The state of the ordinary porous silk fibroin body differs from that of the dried porous silk fibroin body in the amount of water or the like existing in the pores.

In addition, at the time of freeze-drying, it is possible to immerse the silk fibroin porous body in an aqueous glycerin solution in advance or to use glycerin as an additive to be mixed with the aqueous solution of silk fibroin, thereby preventing cracks during drying and being flexible after drying. It is preferable because a complex can be obtained.
In this case, the blending amount of glycerin in the aqueous glycerin solution in which the porous silk fibroin body is immersed is based on the case where the mass of the silk fibroin in the aqueous silk fibroin solution to which the additive used at the time of forming the silk fibroin porous body is added is 1. , 0.25 to 2.5, more preferably 0.38 to 1.9, and even more preferably 0.38 to 1.2. By setting the amount of glycerin in this range, a porous material having good texture and no cracks can be obtained. The dried silk fibroin porous body thus obtained is characterized by containing glycerin even after drying.

The content of glycerin in the dried silk fibroin porous material is preferably from 20 to 70% by mass, more preferably from 25 to 60% by mass, and even more preferably from 30 to 50% by mass. By setting the content of glycerin in the porous body within this range, appropriate flexibility can be imparted to the dried silk fibroin porous body.
The content (% by mass) of glycerin in the dried silk fibroin porous material can be determined by the method described in Examples.

The silk fibroin porous body can be formed into a sheet-like, block-like, tubular, or other suitable shape by appropriately selecting a container into which the silk fibroin aqueous solution containing the additive is poured. A compound having a flat surface is preferable because it can be easily combined with the compound.
Further, the internal structure and hardness of the silk fibroin porous body can be adjusted by adjusting the type of the silk fibroin and the additive used as the raw material, the amount of the additive, and the like.
In this way, gel, sheet, block, etc., silk fibroin porous bodies having various hardnesses can be obtained.

  The average pore diameter of the silk fibroin porous material used in the present invention is preferably from 1 to 500 µm, more preferably from 5 to 300 µm, even more preferably from 10 to 100 µm. When the average pore diameter is within the above range, the feel tends to be good. Also, considering the use as a cell culture support (scaffolding material) for regenerative medicine, cells tend to easily enter pores. The average pore diameter of the silk fibroin porous body can be measured by the method described in Examples.

  The porosity of the porous silk fibroin used in the present invention is preferably from 80 to 99%, more preferably from 90 to 99%, and even more preferably from 94 to 98%. When the porosity is within the above range, the feel tends to be good, and the porous layer is excellent in strength and easy to handle. The porosity of the porous silk fibroin can be measured by the method described in the examples.

  Above, the preferred silk fibroin has been described as an example of fibroin, but a fibroin porous body can be obtained by a similar method using other fibroin, and the porous body can be used in the present invention. is there.

  The size and thickness of the fibroin porous body of the composite of the present invention are not particularly limited, and those having an appropriate size and thickness depending on the application may be used. For example, in the case of a skin care member such as a face mask or an eye mask, it is preferable to use one having a thickness of about 0.2 to 1 mm.

<Thermoplastic resin nonwoven fabric>
The thermoplastic resin nonwoven fabric used in the present invention can be used without particular limitation as long as it is a nonwoven fabric composed of thermoplastic resin fibers.

  The thermoplastic resin constituting the thermoplastic resin fiber is not particularly limited as long as the thermoplastic resin nonwoven fabric and the fibroin porous body can be joined. For example, a (meth) acrylate such as a poly (meth) acrylic ester may be used. ) Acrylic resins; polyvinyl acetal such as polyvinyl butyral (butyral resin); polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polyolefin resins such as polyethylene and polypropylene; styrene resins such as polystyrene and α-methylstyrene; polyoxymethylene Acetal resins such as polyolefin thermoplastic elastomer, polystyrene thermoplastic elastomer, polydiene thermoplastic elastomer, polyurethane thermoplastic elastomer, polyester thermoplastic elastomer, fluorine Thermoplastic elastomers such as fatty thermoplastic elastomers; vinyl chloride resins, polyurethane resins, fluorine resins such as ethylene-tetrafluoroethylene copolymers, polyamides, polyimides, polylactic acids, polycarbonates, polyvinyl acetal resins, liquid crystalline polyester resins, etc. Is mentioned. Among them, those which do not have water solubility are preferable in consideration of use, and polyolefin resins and polyurethane resins are preferable in consideration of form stability, and polylactic acid is also preferable in consideration of biocompatibility.

The fiber diameter of the thermoplastic resin fiber constituting the thermoplastic resin nonwoven fabric is not particularly limited, but in applications where the texture of the reinforcing layer is regarded as important, it is preferable that the average fiber diameter be 1 to 50 μm. , 1 to 30 μm, and more preferably 1 to 20 μm. Thermoplastic nonwoven fabrics having an average fiber diameter in this range tend to have excellent texture.
The average fiber diameter of the thermoplastic resin fibers can be obtained by measuring the width (diameter) of 30 fibers of the thermoplastic resin fibers present at an arbitrary position of the thermoplastic resin nonwoven fabric using an electron microscope (300 times). It can be measured by averaging the values of the respective measurement results.
The thermoplastic resin fiber having the above average fiber diameter can be easily obtained, for example, by forming a nonwoven fabric by a melt blow method.

The size and thickness of the thermoplastic resin non-woven fabric are not particularly limited, and those having an appropriate size and thickness may be used according to the application, but the strength, mass, flexibility, and the like of the obtained composite are considered. Then, it is preferable to use one having an appropriate thickness. Specifically, the thickness of the thermoplastic resin nonwoven fabric is preferably from 1 to 1000 μm, more preferably from 10 to 700 μm, and still more preferably from 50 to 500 μm.
The basis weight of the thermoplastic resin nonwoven fabric, from the same viewpoint, is preferably from 10 to 100 g / ^{m 2,} more preferably from 20 to 70 g / ^{m 2,} further preferably 20 to 50 g / ^{m 2} .

In the present invention, the thermoplastic resin nonwoven fabric may be provided so as to be bonded to at least one surface of the porous fibroin body, and may be provided to be bonded to both surfaces of the porous fibroin body. When the thermoplastic resin nonwoven fabric is provided on both sides of the fibroin porous body, the types and shapes of the thermoplastic resin fibers forming the thermoplastic resin nonwoven fabric may be the same or different, and the use of the composite May be appropriately selected according to the conditions.
Also, after forming a thermoplastic resin nonwoven fabric on both surfaces of the fibroin porous material, the obtained composite is sliced at the fibroin porous material portion to have a thermoplastic resin nonwoven fabric on one surface of the fibroin porous material. A complex can be obtained.

  In the composite of the present invention, the thermoplastic resin for bonding the fibroin porous body and the thermoplastic resin nonwoven fabric is a thermoplastic resin constituting the thermoplastic resin fibers. The bonding form between the fibroin porous body and the thermoplastic resin nonwoven fabric is not particularly limited, but it is preferable that a part of the thermoplastic resin nonwoven fabric in contact with the fibroin porous body is melted and joined to the fibroin porous body.

The tear strength of the composite of the present invention is not particularly limited as long as it has handleability and durability according to the application, but is preferably 250 to 5000 N / m, and more preferably 300 to 2500 N / m. More preferably, it is still more preferably 400 to 2000 N / m. When the tear strength is within the above range, the feel is good, the use feeling does not deteriorate due to the difficulty in bending, and it can be suitably used in various applications.
Here, the tear strength is a value obtained by dividing the median value of the tearing force of the composite by the thickness (m) of the composite. More specifically, it can be measured by the method described in Examples.

[Method for producing composite]
In the method for producing a composite of the present invention, a thermoplastic resin fiber fibrillated by a melt spinning method is accumulated on a fibroin porous body to form a nonwoven fabric composed of the thermoplastic resin fiber on the fibroin porous body. How to
The type, form, production method, and the like of the fibroin porous body and the thermoplastic resin fiber used in the production method of the present invention are the same as those in the composite of the present invention, and the preferred embodiments are also the same.
As a method for forming such a nonwoven fabric, a conventionally known method can be applied, and examples thereof include a spun bond method and a melt blow method, and from the viewpoint of mechanical strength and productivity of the obtained composite, Melt blowing is preferred.
Melt blow method is a method in which a molten thermoplastic resin is blown out in a fibrous form by a high-temperature and high-speed air flow from a die having many fine spinning nozzles and air nozzles, and the fibrous-stretched thermoplastic resin is placed on a conveyor. This is a method of manufacturing a nonwoven fabric by accumulating the fibers during the entanglement and causing entanglement and fusion of the fibers.

Next, a method for producing the composite of the present invention by a melt blow method will be described.
FIG. 3 is a schematic diagram illustrating a melt blow device 30 that can be used in the manufacturing method of the present invention.
First, the fibroin porous body 36 is arranged on the mesh conveyor 33. The porous fibroin body 36 on the mesh conveyor 33 is sent in the traveling direction 39 and is fixed to the mesh conveyor 33 by the suction chuck 37.
On the other hand, the melted thermoplastic resin 31 is supplied to a melt blow die 38 having a number of spinning nozzles and air nozzles, and is spun from the spinning nozzles by hot air 32. At this time, the molten thermoplastic resin 31 is rapidly thinned and fiberized by the hot air 32, and is blown off onto the fibroin porous body 36 by the high-speed airflow, and the thermoplastic resin nonwoven fabric is formed on the fibroin porous body 36. 34 are formed. The composite 35 formed in this manner is sequentially wound by a winding roller for winding the composite.

Various conditions of the melt blowing method may be appropriately adjusted in consideration of the type of the thermoplastic resin, the fiber diameter of the thermoplastic resin fiber, the basis weight of the thermoplastic resin nonwoven fabric, and the like, but may be appropriately adjusted, for example, under the following conditions. it can.
The melting temperature of the thermoplastic resin is, for example, 100 to 250 ° C, and preferably 150 to 250 ° C.
The discharge speed of the thermoplastic resin is, for example, 10 to 500 (g / min), and preferably 30 to 300 (g / min).
The moving speed of the mesh conveyor is, for example, 0.1 to 60 (m / min), and preferably 0.1 to 10 (m / min).
The wind speed of the hot air is, for example, 0.5 to 20 (m / sec), and preferably 1 to 15 (m / sec).
The distance between the spinning nozzle and the compare is, for example, 30 to 200 (cm), and preferably 80 to 150 (cm).

[Use of the composite]
The composite of the present invention and the fibroin porous portion of the composite obtained by the production method of the present invention are excellent in safety, water absorption and the like, and thus can be applied to the field of application to the human body. Since the complex of the present invention has a good touch and a high strength, it can be widely applied to cosmetics and beauty parts. Among them, it is extremely useful as a skin care member such as a face mask and an eye mask because of its features.
In addition, the fibroin porous portion of the composite of the present invention is excellent in safety, cell proliferation, etc., and has high strength as a whole composite, so that it can be suitably used as a scaffold material for regenerative medicine.
Further, the fibroin porous portion of the composite of the present invention is excellent in safety, water absorption and the like, and has high strength as a whole composite, so that it can be suitably used as a wound dressing.
In addition, the present invention can be applied to various industries such as a medical field such as a drug sustained release carrier and an adhesion preventing material, a daily necessity field such as a disposable diaper and a sanitary article, and a support for living microorganisms and bacteria.

  Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

(Evaluation method)
(1) Evaluation of Adhesive Strength With respect to the composites obtained in Examples and Comparative Examples, a portion of the end of the thermoplastic resin non-woven fabric where no silk fibroin porous body was present was picked up with a finger and lifted for 30 seconds to obtain a thermoplastic resin non-woven fabric. The silk fibroin and the porous body of silk fibroin were visually checked for peeling, and evaluated according to the following criteria.
：: There was no peeling at all.
Δ: Almost no peeling occurred.
X: Peeling occurred.
(2) Measurement of tear strength A test piece of a composite obtained by cutting the composite obtained in each of the examples and comparative examples into a size of 100 mm x 15 mm and making a cut of 40 mm in length, and punching into a trouser shape. About, using a universal testing machine (“EZ- (N) S (model number)”, manufactured by Shimadzu Corporation), the load cell is 5 N, the gripper is a tensile test jig, the tearing speed is 200 mm / min, and the initial grip is The median value of the tearing force was measured under the conditions of a tool distance of 40 mm and a room temperature of 22 ° C., and the value was calculated by the following equation.
Tear strength = Median value of tear force (N) / Thickness of test piece (m)
(3) Observation of Cross Section of Composite Using a scanning electron microscope (“Neo Scope JCM-5000”, manufactured by JEOL Ltd.), the cross section of the composite obtained in the example was subjected to high vacuum Pt deposition mode. And an acceleration voltage of 10 kV.
(4) Measurement of Average Fiber Diameter of Thermoplastic Resin Fiber The average fiber diameter of the thermoplastic resin fiber was measured using a scanning electron microscope (“Neo Scope JCM-5000”, manufactured by JEOL Ltd.) (300 times). The measurement was made by measuring the width (diameter) of the 30 thermoplastic resin fibers present at an arbitrary position of the thermoplastic resin nonwoven fabric, and averaging the values of the respective measurement results obtained.

Production Example 1: Production of Silk Fibroin Porous Material (Preparation of Silk Fibroin Aqueous Solution)
The silk fibroin aqueous solution was obtained by dissolving 40 g of a high-pressure scoured cut cocoon (manufactured by Nagasuna Mayon Co., Ltd.) in 400 mL of a 9M lithium bromide aqueous solution, and stirring at room temperature for 24 hours to dissolve. Next, the precipitate was removed by decantation by centrifugation (rotation speed: 12,000 min ^-1 , 5 minutes), and then a dialysis tube (Spectra / Por1 Dialysis Membrane, MWCO 6,000-8,000, Spectrum Laboratories, Inc.), and 5 hours of ultrapure water sampled from an ultrapure water producing apparatus (“PRO-0500 (model number)” and “FPC-0500 (model number)”, manufactured by Organo Corporation) for 12 hours. Was repeated 5 times to obtain an aqueous solution of silk fibroin.
2 mL of the obtained silk fibroin aqueous solution was collected in a polystyrene container, weighed, and then refrigerated freezer (“R-Y370 (model number)”; The mixture was frozen in a freezer of Hitachi, Ltd. for 12 hours, and freeze-dried in a freeze dryer (“FDU-1200 (model number)”, manufactured by Tokyo Rika Kikai Co., Ltd.) for 7 hours. The obtained dried product was taken out from the freeze dryer and weighed within 30 seconds, and the silk fibroin concentration (wt / vol%) in the silk fibroin aqueous solution was quantified from the weight loss.

(Production of porous silk fibroin)
Acetic acid and ultrapure water were added to the silk fibroin aqueous solution whose concentration was measured to prepare a silk fibroin aqueous solution having a silk fibroin concentration of 4 wt / vol% and an acetic acid concentration of 2 vol%. An aluminum container (inside size: 60 mm x 80 mm x 0.4 mm, 60 mm x 80 mm x 0.8 mm, 60 mm x 80 mm x 3 mm) in which the aqueous solution of silk fibroin is affixed with a polytetrafluoroethylene (PTFE) tape on the inner surface. ), Sealed in a low-temperature constant-temperature bath at -5 ° C. (“NCB-3300 (model number), manufactured by Tokyo Rika Kikai Co., Ltd.) and kept for 2 hours. Then, the temperature of the low-temperature constant-temperature bath is increased over 5 hours. The temperature was lowered to −20 ° C., and kept for 5 hours at −20 ° C. The frozen sample was naturally thawed at room temperature and then taken out of the container to obtain a silk fibroin porous material.
The silk fibroin porous body taken out of the container was allowed to stand for 5 days in 10 L of ultrapure water while changing the water every 12 h to remove acetic acid. After removing the acetic acid, the silk fibroin porous material was immersed in 10 L of a 3% by volume glycerin aqueous solution for 3 days, and then frozen in a freezer maintained at -25 ° C for 6 hours. The obtained frozen product was put into a freeze dryer ("FD-550P (model number)", manufactured by Tokyo Rika Kikai Co., Ltd.) and freeze-dried for 3 days. The obtained dried product was used as a dried silk fibroin porous material in the following examples. The porous dried silk fibroin obtained in this manner was soft, had good touch, and had excellent texture.

  When the average pore diameter of the obtained dried silk fibroin porous material was determined, it was found to be 68.3 μm. Here, the average pore diameter was determined by taking five scanning electron micrographs of the porous body, taking five scanning electron micrographs of the porous body produced on different days, and measuring the ten scanning electron micrographs. This is the average value of the pore diameters calculated by performing image processing on an electron micrograph using image analysis software (“ImageJ (trade name)”, manufactured by the National Institutes of Health, USA).

The porosity of the obtained dried silk fibroin porous material was determined to be 96.2%. Here, the porosity is determined by allowing the obtained porous body to stand in pure water for one day to completely absorb water, weighing (wet weight), and freeze-drying to completely remove water in the porous body. It was removed and weighed again (dry weight), assuming that the density of water was 1 g / cm ³ , the density of silk fibroin was 1.2 g / cm ³ , and the density of the water-containing porous silk fibroin was 1 g / cm ^3. It is a value obtained by measuring the porosity of the porous silk fibroin according to the following equation.
Porosity = (wet weight−dry weight / 1.2) / wet weight × 100

Further, whether or not glycerin was contained in the obtained dried silk fibroin porous body was evaluated by total reflection infrared spectroscopy. As an infrared spectrometer, "FTS 6000 SPECTROMETER" (manufactured by Bio-Rad) was used. As a result, as shown in FIG. 2, the obtained porous body has an increased absorption of CO and OH from the scoured silk thread, so that glycerin is contained in the dried silk fibroin porous body. Was found to be included.
In addition, the content (% by mass) of glycerin in the porous dried silk fibroin was determined to be 43.0% by mass.
The content of glycerin in dry silk fibroin porous body C _{G (mass%),} the weight of the dry silk fibroin porous body was introduced glycerin (W _a1), the dry silk fibroin porous body is not installed glycerin since the mass (W _a0), after calculating the dried silk fibroin porous body weight of the introduced glycerin (W _{a1 -W a0),} the mass of dry silk fibroin porous body was introduced glycerin (W _a1) The value was calculated by the following formula.
_CG (% by mass) = [(W _a1 −W _a0 ) / W _a1 ] × 100

Example 1
Using the melt-blowing apparatus 30 having the structure shown in FIG. 3, while fixing the silk fibroin porous body 36 placed on the mesh conveyor 33 with the suction chuck 37, the spinning nozzle installed on the upper part of the suction chuck 37 shown in Table 1 The fibers 31 made of the thermoplastic resin shown were discharged, and a nonwoven fabric was formed on the porous silk fibroin body 36 to obtain a composite 35. The obtained composite 35 was evaluated for adhesion by the method described above. Table 1 shows the conditions of melt blowing and the evaluation results of the adhesiveness.

Examples 2 to 4
Example 2 Example 2 was repeated in the same manner as in Example 1 except that the type of the thermoplastic resin, the melting temperature, the hot air wind speed, and the distance between the spinning nozzle and the mesh conveyor were changed as shown in Table 1. ~ 4 composites were prepared. Table 1 shows the conditions of melt blowing and the evaluation results of the adhesiveness.

The types of the thermoplastic resins described in Table 1 are as follows.
a: Polyurethane (“ET385-10MS Clear”, manufactured by BASF Japan Ltd.)
b: Polylactic acid ("Ingeo Grade 6201D", manufactured by Nature Works Japan Co., Ltd.)

  From Table 1, it can be seen that the composites of the present invention obtained in Examples 1 to 4 have excellent adhesion between the porous silk fibroin body and the thermoplastic resin fiber.

  Furthermore, the structure of the cross section obtained by cutting the composite prepared in Example 2 with a surgical knife so that the blade passes from the thermoplastic resin nonwoven fabric side to the porous layer side was observed using a scanning electron microscope. . Using a scanning electron microscope, “Neo Scope JCM-5000” manufactured by JEOL Ltd., measurement was performed in a high vacuum Pt deposition mode at an acceleration voltage of 10 kV. FIG. 4 shows a scanning electron micrograph of a cross section of the observed composite. From FIG. 4, it was found that a thermoplastic resin nonwoven fabric was formed on the silk fibroin porous body.

Next, in order to evaluate the mechanical strength of the composite, the tear strength of the composite obtained in Example 1 was measured by the method described above.
As Comparative Example 1, the tear strength of the porous silk fibroin produced in Production Example 1 was measured under the same conditions. Table 2 shows the results.

  From Table 2, it can be seen that the composite of the present invention obtained in Example 1 has better tear strength than the porous body of Comparative Example 1 having no thermoplastic resin nonwoven fabric.

DESCRIPTION OF SYMBOLS 10 Composite 11 Thermoplastic resin nonwoven fabric 12 Fibroin porous material 30 Mesh blow device 31 Melted thermoplastic resin 32 Hot air 33 Mesh conveyor 34 Thermoplastic resin nonwoven fabric 35 Composite of the present invention 36 Fibroin porous material 37 Suction chuck 38 Mesh Blowing die 39 Propagation direction 41 of mesh conveyor 41 Thermoplastic nonwoven fabric 42 Porous silk fibroin

Claims (6)

And fibroin porous body, and a formed non-woven fabric of thermoplastic resin fibers, and the porous body and the nonwoven fabric, Ri Na joined by thermoplastic resin constituting the thermoplastic resin fibers, the heat A composite , wherein the plastic resin is polyurethane . Basis weight of the formed nonwoven by the thermoplastic resin fiber is 10 to 100 g / ^{m 2,} the composite body according to claim 1. 3. The composite according to claim 1, wherein the thermoplastic resin fiber has a fiber diameter of 1 to 50 μm. 4. The complex according to any one of claims 1 to 3 , wherein the fibroin porous body contains glycerin. The method for producing a composite according to any one of claims 1 to 4 , wherein thermoplastic resin fibers fiberized by a melt spinning method are accumulated on the fibroin porous body, and the fibrin porous body is formed on the fibroin porous body. A method for producing a composite, wherein a nonwoven fabric composed of the thermoplastic resin fibers is formed. The method for producing a composite according to claim 5 , wherein the melt spinning method is a melt blow method.