Silk fibroin molding base and manufacturing method

Abstract

The present disclosure provides a fibroin molding element that can be easily molded without the hassle of lamination, and a molding element that is mainly composed of silk fibroin and has a bulk density of 0.70 g / cm. 3 ~1.20g / cm 3 The present invention provides a method for producing a fibroin molded article, characterized by:

Description

[Technical Field]

[0001] [Technical field]

[0002] The present disclosure relates to a silk fibroin molding element and a method for producing the same. [Background technology]

[0003] [Background technology]

[0004] International Patent Application Publication No. 2017 / 047503 provides a molded body obtained by filling a mold with a powder of a protein containing a natural spider silk protein, which is silk fibroin, or a polypeptide derived from a natural spider silk protein, and then heating and pressurizing it. Summary of the Invention

[0005] [Disclosure Summary]

[0006] When silk fibroin powder is used as a base material for molding, it tends to scatter and adhere to the surrounding area, which makes it difficult to fill a stable amount into a mold, resulting in inconsistent filling amounts and unstable dimensions of the molded product.If the filling amount is insufficient, the silk fibroin will not be pressurized within the mold, resulting in an insufficient transfer of the mold's surface shape and a decrease in the strength of the molded product.

[0007] The present disclosure provides a silk fibroin molding material that can be stably molded, and a method for producing a silk fibroin molded product.

[0008] Specifically, in the present disclosure, a bulk density of approximately 0.70 g / cm 3 ~1.20g / cm 3 The present invention provides a molding element comprising silk fibroin as a main component. In one aspect, the element has a thickness of about 100 μm or more. In another aspect, the element has a β-sheet content of less than about 10% and / or a water content of about 2 to about 15%.

[0009] In a further aspect, the element may have a cylindrical, polygonal, spherical, or hemispherical shape. In yet another aspect, the element may contain silk fibroin as a main component and have a bulk density of approximately 0.70 g / cm. 3 ~Approximately 1.20g / cm 3 In a further aspect, the set of elements includes a package made of paper, resin, rubber, or metal.

[0010] In yet another embodiment, an aqueous solution of silk fibroin containing less than 10 g of silk fibroin is dispensed, and the solution is freeze-dried to obtain a freeze-dried product having a bulk density of approximately 0.70 g / cm. 3 ~Approximately 1.20g / cm 3 and then applying heat and pressure to the compressed body.

[0011] In another embodiment of the molding method, the amount of solids in the dispensed aqueous solution is the same as or 1 / N of the weight of the molded body.

[0012] According to the present disclosure, silk fibroin has a bulk density of approximately 0.70 g / cm 3 ~Approximately 1.20g / cm 3 Since the silk fibroin is compressed to a constant density, scattering and adhesion to the surrounding area are suppressed compared to silk fibroin powder, and the amount of filling into the mold is constant. Furthermore, since the filling amount is constant, the dimensions of the molded product are also constant, improving the transferability of the mold shape to the molded product and suppressing a decrease in the mechanical strength of the molded product.

[0013] These and other embodiments, objects, features, and advantages of the present disclosure will become apparent from the following detailed description of exemplary embodiments of the present disclosure, read in conjunction with the accompanying drawings and the appended claims. [Brief explanation of the drawings]

[0014] [Brief description of the drawing]

[0015] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate various embodiments, objects, features, and advantages of the present disclosure.

[0016] [Figure 1] FIG. 1 is a schematic diagram of a mold for molding silk fibroin.

[0017] [Figure 2] FIG. 1 shows a block for freeze-drying.

[0018] [Figure 3A] , and [Figure 3B] FIG. 3 is a diagram showing a cross section of the freeze-drying block of FIG. 2.

[0019] [Figure 4] FIG. 1 is a diagram showing the components of the process for obtaining a silk fibroin molding body.

[0020] Throughout the drawings, the same reference numerals and characters, unless otherwise stated, are used to denote like features, elements, components, or portions of the illustrated embodiments. Moreover, while the present disclosure will now be described in detail with reference to the drawings, it is done so in connection with the exemplary embodiments for purposes of illustration. It is intended that changes and modifications can be made to the exemplary embodiments described without departing from the true scope and spirit of the present disclosure, as defined by the appended claims. Furthermore, each described embodiment can be manufactured or used in combination with any other described embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0021] Detailed Description of the Embodiments

[0022] This disclosure describes several embodiments and relies on patents, patent applications, and other references for details known to those skilled in the art. Accordingly, when a patent, patent application, or other reference is cited or repeated herein, it should be understood that it is incorporated herein by reference in its entirety for all purposes, not just as provided herein.

[0023] The silk fibroin molding material of this embodiment contains silk fibroin and has a bulk density of 0.70 g / cm 3 ~1.20g / cm 3 The range is as follows: A molding element (molding element) is an element used when molding a functional solid material whose main raw material is silk fibroin into a desired shape.

[0024] The protein composition can be used as a base for a molded body to form the protein molded body of this embodiment. 3 ~1.20g / cm 3 By adjusting the thickness within this range, the silk fibroin molding element has an appropriate strength and weight, which prevents scattering and adhesion.

[0025] Below, we will explain silk fibroin, adjusting bulk density, and molding.

[0026] [Silk fibroin]

[0027] Silk fibroin is a fibrous protein that can be extracted from cocoons and / or nests. Silk fibroin can be extracted, for example, by the method described in WO2006 / 101223.

[0028] Silk fibroin is generally characterized by a high proportion of glycine, alanine, serine, and tyrosine. Examples of silk fibroin include silk fibroin derived from organisms classified into the order Lepidoptera, Hymenoptera, or Araneae. Silk fibroin may also be obtained by genetic engineering.

[0029] In addition, additives may be added to silk fibroin within the range that does not impair its properties.

[0030] [Bulk density adjustment]

[0031] If the bulk density is low, the tableting strength will be low, and the tablet will break down when put into the mold and will easily scatter around. Therefore, the bulk density should be 0.70 g / cm 3 More than 0.90g / cm 3 or more, or 1.00 g / cm 3 On the other hand, if the bulk density is high, the surface transferability deteriorates during molding, so the bulk density should be 1.20 g / cm 3 Must be less than 1.10g / cm 3 There are no particular limitations on the method for adjusting the bulk density of silk fibroin, but examples include a method of adjusting the bulk density by pulverizing and compressing silk fibroin powder, and a method of drying an aqueous silk fibroin solution before it is produced as a powder or in which the powder has been redissolved to prepare a silk fibroin porous body with a low bulk density, and then compressing this to a desired bulk density to obtain a molding element.

[0032] The former method of adjusting the bulk density will be explained.

[0033] Silk fibroin loses bulk density when pulverized to a smaller particle size, so the bulk density can be adjusted by controlling the pulverized particle size. A jet mill, pin mill, hammer mill, or the like can be used for pulverization. Silk fibroin increases bulk density when compressed. The bulk density can be adjusted by controlling the pressure during compression. A compression molding machine or tablet press can be used for compression.

[0034] Next, the latter bulk density adjustment method will be described.

[0035] The method for dissolving silk fibroin in water is not particularly limited. For example, since silk fibroin has low solubility in water, a method in which silk fibroin is dissolved in a highly concentrated aqueous solution of lithium bromide and then desalted by dialysis to prepare a silk fibroin aqueous solution can be exemplified.

[0036] The method for drying the silk fibroin aqueous solution is not particularly limited as long as it can remove the solvent without decomposing the silk fibroin, and examples include air drying, heat drying, vacuum drying, spray drying, and freeze-drying. The advantage of freeze-drying is that the solution is frozen at a low temperature and the solvent is removed by sublimation, thereby suppressing the decomposition of the silk fibroin. For example, one method for forming silk fibroin involves dispensing an aqueous silk fibroin solution containing less than 10 g of silk fibroin, freeze-drying the solution, and then pulverizing the solution to form a silk fibroin having a bulk density of approximately 0.70 g / cm. 3 ~Approximately 1.20g / cm 3The freeze-dried product is then compressed and heated under pressure until the resulting freeze-dried product is lyophilized. This process can utilize blocks 31 and 32, as shown in FIG. 2. Block 31 can be used to freeze-dry a single portion of the fibroin aqueous solution, while block 32 can be used to freeze-dry multiple portions of the silk fibroin aqueous solution simultaneously. The through-holes 33 in each of the blocks 31 and 32 are configured to receive single or multiple portions of the fibroin aqueous solution before freezing. Cross-sectional views of the blocks 31 and 32 are provided in FIGS. 3A and 3B. In FIG. 3A, the blocks 31 and 32 include through-holes 33 into which the silk fibroin aqueous solution 21 is injected. A member 34 serves as a stopper at one end of the through-hole 33, retaining the silk fibroin aqueous solution within the through-hole 33. In FIG. 3B, freeze-drying is performed, resulting in the freeze-dried silk fibroin 22 remaining within the through-holes 33 of the blocks 31 and 32. The member 34 remains at one end of the through-hole 33 as a stopper. 4 shows the molding process for obtaining a molding element. Freeze-dried silk fibroin 22 is poured into a mold 35 having through-holes and a member 36 for holding the poured material inside the through-holes. The freeze-dried silk fibroin 22 is compressed with a piston 37 to adjust the bulk density of the poured material, thereby obtaining a molding element 24. The pressure during compression is not limited, but may be, for example, 30 MPa.

[0037] In addition to bulk density, the configuration of the silk fibroin molding element will be described from the viewpoint of tablet hardness. The tablet hardness of the silk fibroin molding element may be 10 or more and 130 or less. Within this range, the silk fibroin molding element will not scatter when placed in a mold, and surface transferability will be good, allowing the effects of the present disclosure to be obtained. In a further embodiment, the tablet hardness of the silk fibroin molding element is 20 or more and 120 or less, or 30 or more and 115 or less.

[0038] In one embodiment, the moisture content after drying is about 2 to 15%, which increases the fluidity during fibroin molding and improves surface transferability.

[0039] If the β-sheet structure progresses after drying, the surface transferability deteriorates, and therefore, in one embodiment, the β-sheet ratio is less than 10%.

[0040] Furthermore, when drying, it is desirable to divide the silk fibroin into uniform amounts, or to divide (dispense) into portions (aliquots) into the aqueous solution the amount of silk fibroin required for one molding run, or an amount equivalent to 1 / N (N is an integer) of that amount, and then dry the resulting solution. Generally, measuring a liquid is more accurate than measuring a powder, so dividing the aqueous solution into fixed amounts and drying them allows for more accurate measurement than measuring after drying. To simplify weighing, N can typically be 2, 3, or 5 or less. It is also desirable for the weight of silk fibroin in the aqueous silk fibroin solution after dispensing to be approximately 10 g or less.

[0041] The silk fibroin molding element can be formed into a cylindrical, polygonal, spherical, or hemispherical shape. This is because adjusting the bulk density by compression allows for uniform pressure to be applied to the silk fibroin when obtaining the silk fibroin molding element, thereby maintaining uniform hardness and other properties within the molding element. When uniaxial compression is performed to obtain the silk fibroin molding element, the molding element may have a cylindrical shape. For uniform compression, a certain condition is provided for the height (thickness) of the molding element to be no more than 3 times and no less than 0.1 times the diameter (or width or length). The height (thickness) of the silk fibroin molding element may also be 1 mm or more. This is because if the silk fibroin molding element is too thin, restrictions may be placed on the shape of the product after molding using this element. The thickness of the element may further be 1.5 mm or more, or 2.0 mm or more.

[0042] [Molding]

[0043] A silk fibroin molding material with adjusted bulk density can be placed in a mold and heated and pressurized to obtain a silk fibroin molding product. Figure 1 is a schematic diagram of an example of a mold that can be used to mold silk fibroin. The mold is composed of a temperature-controllable member 3 with a through-hole and upper and lower pistons 1 and 2. The silk fibroin molding material can be placed in member 3 and compressed by moving pistons 1 and 2 up and down to obtain a silk fibroin molding product.

[0044] Heating in the heating and pressurizing step can be carried out at 70°C to 200°C, or 100°C to 150°C. If the temperature is below 70°C, the proteins will not be sufficiently integrated, and the molded body will not have sufficient strength. On the other hand, if the temperature is above 200°C, the proteins will begin to decompose, and there is a risk of a decrease in strength. Pressurizing can be carried out at 10 MPa or higher. If the pressure is below 10 MPa, the proteins will not be sufficiently integrated, and the molded body will not have sufficient strength. Pressurizing may be carried out at 50 MPa or higher.

[0045] After the predetermined pressure is reached, the pressure may be maintained for 0 to 60 minutes, or 10 to 30 minutes. After removal from the mold, the product may be heat-treated at 70 to 150°C. Heat treatment promotes crystallization, improving strength and shape stability.

[0046] [Measurement method]

[0047] The measurement method required for this disclosure will be described below.

[0048] The bulk density was measured using the bead displacement method. Specifically, a pre-weighed amount of quartz sand (0.3-0.5 mm) was placed in a volumetric scale, and then silk fibroin was added to the scale. The bulk density was estimated from the weight of the scale and the increase in volume.

[0049] The hardness of the prepared tablets was measured using a load cell type tablet hardness tester (PC-30, Okada Seiko Co., Ltd.).

[0050] The β-sheet ratio was measured using FT-IR (Frontier MIR NIR / Spotlight 400, Perkin Elmer). -1 The absorbance was measured in the range of 1600-1650cm -1 The peak wavelength N was read and the β-sheet ratio was calculated using the formula 1.

[0051] β-sheet ratio (%) = (1641-N) / 20 × 100 Equation 1

[0052] The reason for using Equation 1 is that the peak wavelength is 1641 cm in the amorphous state. -1 and in the fully crystalline state, it is 1621 cm -1 This is because:

[0053] The flexural modulus was measured using an Instron universal testing machine (Model 5582, Instron). The distance between the three-point bending supports was fixed at 27 mm, and the measurement speed was set at 1 mm / min. The flexural modulus was calculated from the displacement (strain) from 0.05 to 0.25%.

[0054] The surface roughness was measured using a surface roughness meter (Surfcorder SE3500, Kosaka Laboratory Co., Ltd.), and the ten-point average roughness Rzjis was measured in accordance with JIS B0601-1994.

[0055] [Example]

[0056] [Example 1]

[0057] After washing the silkworm cocoons, they were boiled in a 0.02 mol / L aqueous sodium carbonate solution for 30 minutes to refine the cocoons. After drying, the refined silk fibroin was placed in a 9.3 mol / L LiBr solution and dissolved by stirring at 60°C for 4 hours. The silk fibroin was desalted using a Sekisui Chemical Co., Ltd. 30 / 32 dialysis flask (molecular weight cutoff: 12,000-14,000). The desalted fibroin solution was diluted with pure water to a concentration of 5%.

[0058] The obtained 5% fibroin aqueous solution was divided into 26.4 ml portions into containers as shown in Figure 2. In Figure 2, reference numerals 31 and 32 respectively indicate blocks for subsequent freeze-drying, and reference numeral 33 indicates a hole into which the silk fibroin aqueous solution was injected.

[0059] The dispensed fibroin solution was freeze-dried using a freeze-dryer (FD-550P) manufactured by Tokyo Rikakikai Co., Ltd. (Fig. 3). Figures 3A and 3B each show a cross-sectional view of the freeze-drying block shown in Fig. 2. Reference numeral 21 denotes the aqueous silk fibroin solution before freeze-drying, and reference numeral 22 denotes the freeze-dried silk fibroin. Reference numeral 34 denotes a member for holding the fibroin solution in place. The freeze-drying conditions were as follows: after freezing at -30°C, the atmosphere was reduced in pressure, and then the temperature was raised to -6°C, and freeze-drying was carried out for 100 hours. The bulk density was measured and found to be 0.03 g / cm. 3 It was.

[0060] Next, one piece of freeze-dried silk fibroin was placed in a mold with a cylindrical through-hole of 5 mm diameter, pressurized at 25°C and 30 MPa, and then removed to obtain a molding element (Figure 4). In Figure 4, reference numerals 35 and 36 indicate molds for obtaining the molding element. Reference numeral 37 indicates a compression piston. Reference numeral 24 indicates the silk fibroin molding element obtained through this process. The same mold as the freeze-drying blocks 31, 32, and 34 may also be used as the mold for obtaining the molding element.

[0061] The bulk density of the obtained molding body was measured and found to be 1.02 g / cm 3 The β-sheet ratio was measured to be 5%. The moisture content was measured to be 7%. The tablet hardness was measured to be 103 N, and a molding element having a good hardness that did not crumble even when held with tweezers or the like was obtained. A plurality of molding elements thus obtained may be placed together in a package and then transferred to the main molding step. The package may be made of paper, resin, rubber, metal, etc.

[0062] The molding element was then molded by heating and pressurizing. A mold was used that had a rectangular prism-shaped through-hole 35 mm long and 15 mm wide. A piston with a surface roughness Rz of 0.2 μm was used. The molding element was placed in a mold that had been pre-heated to 125°C, and pressure was applied at 100 MPa for 30 seconds, and the mold was allowed to cool to 25°C. The silk fibroin molded product was removed from the mold, and the surface roughness of the surface that had come into contact with the piston was measured. It was found to be 2.3 μm, indicating good surface transfer.

[0063] [Example 2]

[0064] A silk fibroin molding element was obtained in the same manner as in Example 1, except that the freeze-dried silk fibroin was pressed at 20 MPa. The bulk density of the obtained molding element was measured and found to be 0.72 g / cm. 3 The β-sheet ratio was measured to be 5%. The moisture content was measured to be 7%. The tablet hardness was measured to be 34 N, and a molding base having a good hardness that did not disintegrate even when held with tweezers or the like was obtained.

[0065] A silk fibroin molded product was obtained by the same procedure as in Example 1. The surface roughness was measured and found to be 2.2 μm, indicating good surface transfer.

[0066] [Comparative example A]

[0067] A silk fibroin molding element was obtained in the same manner as in Example 1, except that the freeze-dried silk fibroin was pressed at 2 MPa. The bulk density of the obtained molding element was measured and found to be 0.50 g / cm. 3 The beta sheet ratio was measured to be 5%. The moisture content was measured to be 7%. The tablet hardness was measured to be 10 N or less. When held with tweezers, the tablet disintegrated into many pieces, making it difficult to handle.

[0068] The collapsed pieces were collected, and a silk fibroin molded product was obtained by the same procedure as in Example 1. The surface roughness was measured and found to be 2.3 μm, indicating good surface transfer.

[0069] [Example 3]

[0070] A silk fibroin molding element was obtained in the same manner as in Example 1, except that the freeze-dried silk fibroin was pressed at 80 MPa. The bulk density of the obtained molding element was measured and found to be 1.20 g / cm. 3 The β-sheet ratio was measured to be 5%. The moisture content was measured to be 7%. The tablet hardness was measured to be 114 N, and a molding base having a good hardness that did not disintegrate even when held with tweezers or the like was obtained.

[0071] A silk fibroin molded product was obtained by the same procedure as in Example 1. The surface roughness was measured and found to be 2.3 μm, indicating good surface transfer.

[0072] [Comparative example B]

[0073] A silk fibroin molding element was obtained in the same manner as in Example 1, except that the freeze-dried silk fibroin was pressed at 120 MPa. The bulk density of the obtained molding element was measured and found to be 1.28 g / cm. 3 The β-sheet ratio was measured to be 5%. The moisture content was measured to be 7%. The tablet hardness was measured to be 132 N, and a molding base having a good hardness that did not disintegrate even when held with tweezers or the like was obtained.

[0074] A silk fibroin molded product was obtained by the same procedure as in Example 1. The surface roughness was measured and found to be 17.2 μm. This is thought to be because the bulk density of the molding element had increased, making it hard, and therefore surface transfer was insufficient.

[0075] [Example 4]

[0076] The freeze-dried silk fibroin was kept in an environment of 100°C for 4 minutes, and then left at 23°C and 50% relative humidity for 48 hours. A silk fibroin molding element was obtained in the same manner as in Example 1, except that it was pressurized at 20 MPa. The bulk density of the obtained molding element was measured and found to be 1.03 g / cm. 3 The β-sheet ratio was measured to be 8%. The moisture content was measured to be 7%. The tablet hardness was measured to be 95N, and a molding base having a good hardness that did not crumble even when held with tweezers or the like was obtained.

[0077] A silk fibroin molded product was obtained by the same procedure as in Example 1. The surface roughness was measured and found to be 2.3 μm, indicating good surface transfer.

[0078] [Example 5]

[0079] The freeze-dried silk fibroin was kept in an environment of 90°C for 3 minutes, and then left at 23°C and 50% relative humidity for 30 minutes. After that, a silk fibroin molding element was obtained in the same manner as in Example 1, except that it was pressed at 20 MPa. The bulk density of the obtained molding element was measured and found to be 1.09 g / cm. 3 The β-sheet ratio was measured to be 5%. The moisture content was measured to be 2%. The tablet hardness was measured to be 75N, and a molding base having a good hardness that did not disintegrate even when held with tweezers or the like was obtained.

[0080] A silk fibroin molded product was obtained by the same procedure as in Example 1. The surface roughness was measured and found to be 2.3 μm, indicating good surface transfer.

[0081] [Example 6]

[0082] The freeze-dried silk fibroin was left at 23°C and a relative humidity of 80% for 12 hours. After that, a silk fibroin molding element was obtained in the same manner as in Example 1, except that it was pressed at 20 MPa. The bulk density of the obtained molding element was measured and found to be 1.12 g / cm. 3The β-sheet ratio was measured to be 5%. The moisture content was measured to be 15%. The tablet hardness was measured to be 89 N, and a molding base having a good hardness that did not crumble even when held with tweezers or the like was obtained.

[0083] A silk fibroin molded product was obtained by the same procedure as in Example 1. The surface roughness was measured and found to be 2.4 μm, indicating good surface transfer.

[0084] [Example 7]

[0085] A silk fibroin molding element was obtained in the same manner as in Example 4, except that the holding time in the 100°C environment was changed from 4 minutes to 7 minutes. The bulk density of the obtained molding element was measured and found to be 1.02 g / cm. 3 The β-sheet ratio was measured to be 13%. The moisture content was measured to be 7%. The tablet hardness was measured to be 68 N, and although deformation was observed when pinched firmly with tweezers, a molding base body with a hardness sufficient to prevent disintegration was obtained.

[0086] A silk fibroin molded product was obtained by the same procedure as in Example 1. The surface roughness was measured and found to be 2.9 μm, indicating good surface transfer.

[0087] [Example 8]

[0088] A silk fibroin molding element was obtained in the same manner as in Example 5, except that the holding time at 90°C was changed from 3 minutes to 5 minutes. The bulk density of the obtained molding element was measured and found to be 1.04 g / cm. 3 The β-sheet ratio was measured to be 5%. The moisture content was measured to be 1%. The tablet hardness was measured to be 47N, and although deformation was observed when pinched firmly with tweezers, a molding base body with a hardness that did not disintegrate was obtained.

[0089] A silk fibroin molded product was obtained by the same procedure as in Example 1. The surface roughness was measured and found to be 4.2 μm, indicating good surface transfer.

[0090] [Example 9]

[0091] The freeze-dried silk fibroin was left at 23°C and a relative humidity of 80% for 24 hours. After that, a silk fibroin molding element was obtained in the same manner as in Example 1, except that it was pressed at 20 MPa. The bulk density of the obtained molding element was measured and found to be 1.02 g / cm. 3 The β-sheet ratio was measured to be 5%. The moisture content was measured to be 17%. The tablet hardness was measured to be 41 N, and a molding base having a good hardness that did not crumble even when held with tweezers or the like was obtained.

[0092] Silk fibroin molded articles were obtained by the same procedure as in Example 1. The surface roughness was measured to be 3.6 μm, indicating good surface transfer. The results of the examples and comparative examples are summarized in Tables 1A and 1B, with X = poor, △ = fair, ○ = good, and ⊚ = excellent. [Table 1] [Table 2]

Claims

1. A molding element having silk fibroin as a main component and having a bulk density of approximately 0.70 g / cm ３ ~1.20 g / cm ３ A molding element characterized by:

2. 2. The molding element according to claim 1, wherein the thickness of the element is 1 mm or more.

3. 3. The molding element according to claim 1, wherein the element has a β-sheet ratio of less than 10%.

4. 4. The molding element according to claim 1, wherein the moisture content of said element is about 2 to about 15%.

5. 5. The molding element according to claim 1, wherein the element has a cylindrical, polygonal prism, spherical, or hemispherical shape.

6. A molding element having silk fibroin as a main component, characterized in that the tablet hardness is 10 or more and 130 or less.

7. 7. The molding element according to claim 6, wherein the tablet hardness is 30 or more and 115 or less.

8. 8. The molding element according to claim 6, wherein the thickness of the element is 1 mm or more.

9. 9. The molding element according to claim 6, wherein the element has a β-sheet ratio of less than 10%.

10. 10. The molding element according to claim 6, wherein the moisture content of the element is 2 to 15%.

11. 11. The molding element according to claim 6, wherein the element has a cylindrical, polygonal prism, spherical, or hemispherical shape.

12. freeze-drying the silk fibroin aqueous solution; Bulk density is 0.7 g / cm ３ ~1.2 g / cm ３ compressing the freeze-dried material until A method for producing a silk fibroin molding element, comprising:

13. The method for producing a silk fibroin molding body according to claim 12, characterized in that the freeze-drying step is carried out using an aqueous silk fibroin solution dispensed so that the solid content concentration is 10 g or less.

14. Bulk density is 0.70 g / cm ３ ~1.20 g / cm ３ Setting a molding element containing silk fibroin as a main component in a mold; and heating and pressurizing the molding element to obtain a silk fibroin molded product.

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