Manufacturing of moldings using compositions for molding containing pyrolyzable wastewater substances and fibroin

Abstract

To provide a manufacturing method for improving the molding flowability when obtaining molded parts containing protein, as well as a method for manufacturing molded parts with improved protein moldability.SOLUTION: A manufacturing method of a compact, including heating a composition for molding containing a pyrolytic wastewater substance that decomposes by pyrolysis to produce water molecules and fibroin, and pressurizing the composition for molding while pyrolyzing the pyrolytic wastewater substance.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] [Technical Field]

[0002] The present invention relates to a method for manufacturing a molded body containing fibroin.

Background Art

[0003] [Background Art]

[0004] Efforts have been made to process various products using hydrophilic fibroin.

[0005] Since fibroin has high hydrophilicity and strong intermolecular bond strength due to hydrogen bonds, intermolecular bonding may occur when heat or pressure is applied in the molding process, and the fluidity of the protein may decrease. Therefore, relatively high pressure is usually required.

[0006] International Publication No. 2019054503 provides a molding method for molding a protein at a relatively low pressure by adding a solvent such as water to improve fluidity.

[0007] However, it is difficult to uniformly mix a small amount of solvent and protein, and in regions where they are not sufficiently mixed, the shape transferability at low pressure may be insufficient. Also, since the molding and curing speed of the protein is non-uniform in-plane, the pressure propagation becomes non-uniform, and the shape transferability may become insufficient. On the other hand, when the amount of solvent is increased, the fluidity of the protein is improved at low pressure. However, due to the rapid heat of vaporization of water generated by the molding heat of the protein, heat may be taken away, and it may not be possible to obtain a molded body of the desired shape without the protein flowing.

[0008] An object of the present invention is to improve the molding fluidity when obtaining a molded part containing a protein.

Summary of the Invention

[0009] [Summary of the Invention]

[0010] The present disclosure relates to a manufacturing method including a process of heating a composition for molding, which includes a pyrolytic water substance decomposed by pyrolysis to generate water molecules and fibroin, and a process of pressure molding while subjecting the pyrolytic water substance to pyrolysis.

[0011] These and other embodiments, objects, features, and advantages of the present disclosure will become apparent when taken in conjunction with the accompanying drawings and the claims provided, upon reading the following detailed description of the exemplary embodiments of the present disclosure.

Brief Description of the Drawings

[0012] [Brief Description of the Drawings]

[0013] The accompanying drawings incorporated herein and forming a part of the specification illustrate various embodiments, objects, features, and advantages of the present disclosure.

[0014]

Figure 1

[0015]

Figure 2A

Figure 2B

Figure 2C

Figure 2D

[0016]

Figure 3

[0017]

Figure 4

[0018] Throughout the figures, unless otherwise specified, the same reference numerals and characters are used to represent features, elements, components, or parts of the illustrated embodiments. Further, although the disclosure of the subject matter is described in detail herein with reference to the figures, it is done so in relation to exemplary embodiments. It is intended that changes and modifications can be made to the described exemplary embodiments without departing from the true scope and spirit of the subject matter disclosed by the appended claims.

Embodiments for Carrying Out the Invention

[0019] [Embodiments for Carrying Out the Invention]

[0020] This disclosure has several embodiments and relies on patents, patent applications, and other references that are known in detail in the relevant technical field. Therefore, when a patent, patent application, or other reference is cited or repeated in this specification, it should be understood that it is incorporated by reference in its entirety for all purposes, as if the proposition described therein were set forth in full.

[0021] [Composition for Molding]

[0022] The composition for molding of the present disclosure contains a pyrolyzable drainage substance. As used herein, a pyrolyzable drainage substance means a compound that is a solid at or below normal temperature but decomposes (pyrolyzes) upon heating and contains water molecules in the decomposition products. Here, normal temperature is, for example, 27°C. By mixing the pyrolyzable drainage substance with a molding element (e.g., a protein-containing powder) and compression molding it, the pyrolyzable drainage substance decomposes due to the heat generated during molding. When the protein absorbs the moisture generated at this time, the fluidity of the protein is improved. That is, the viscosity of the composition can be reduced.

[0023] An exemplary process for obtaining a composition for forming is described in Figure 3. In step S11, the aqueous solution is prepared as otherwise described in the present disclosure above. In step S12, a thermally decomposable drainage substance is added to the aqueous solution as described above. In step S13, water is removed from the aqueous solution containing the thermally decomposable drainage substance as described above. Subsequently, the dry sheet of the composition obtained from step S13 can be pulverized into a powder.

[0024] Regarding the decomposition of the thermally decomposable drainage substance, in TGA measurement, when heated at a heating rate of 10 °C / min from 30 °C, the weight loss amount can be less than 1 part by weight at 50 °C. In the case of a higher decomposition rate, thermal decomposition can proceed even at room temperature. Also, the thermal decomposition start temperature (T1 (°C)) of the thermally decomposable drainage substance can be set to be less than the protein decomposition start temperature. When the thermal decomposition start temperature of the thermally decomposable drainage substance is higher than that, in order to generate moisture from the thermally decomposable drainage substance, it is necessary to raise the forming temperature to near the protein decomposition start temperature, and there is a risk that the protein will deteriorate during forming. Here, the deterioration of the protein means that the covalent bond of the molecular chain constituting the protein is broken and the molecular weight decreases. When protein deterioration occurs, the mechanical strength and the like of the formed part obtained after forming decrease, and the integrity as a formed part is impaired. Usually, the start temperature of protein decomposition is said to be around 200 °C, and this thermally decomposable drainage substance can complete decomposition at 180 °C or lower.

[0025] It is possible to confirm the start temperature of protein decomposition by thermogravimetric analysis (TGA). First, the sample is heated to 120 °C at a heating rate of 10 °C / min under atmospheric pressure, then held for 30 minutes to remove the influence of moisture, and further heated to 400 °C at a heating rate of 1 °C / min. In the weight loss graph obtained at this time, the intersection of the straight line extending the straight line on the high temperature side when the weight is stable at 120 °C and the tangent line at the inflection point of the weight loss during decomposition is taken as the decomposition start temperature.

[0026] Whether the decomposition temperature of the pyrolyzable drainage substance is completed below 180°C can be confirmed by the TGA of the pyrolyzable drainage substance itself. Specifically, in the TGA measurement, when the sample is heated from 30°C to 500°C at a heating rate of 10°C per minute, the weight loss rate below 180°C is compared with the weight loss rate above 180°C. If the latter is negligibly small, it can be said that the decomposition is completed at 180°C. The decomposition rate at the completion of this decomposition is set to 100%. Separately, by heating from 30°C to 100°C or 150°C, setting to a constant temperature, and measuring the time until the decomposition rate reaches 100%, it can be used as an indicator for the temperature and time conditions of processing such as molding.

[0027] The amount of water released from the pyrolyzable drainage substance can be calculated based on the molecular structure and decomposition reaction formula. It can also be confirmed by decomposing the solid by heating it above the decomposition temperature in the flask of the distillation apparatus, cooling the generated water vapor, and collecting the amount of the collected water droplets. In the case of pyrolyzable drainage substances such as ammonium carbonate and ammonium bicarbonate that do not contain solids in the decomposition product, it can also be confirmed by heating in a sealed container, cooling, removing the generated gas and decomposing it, and then examining the weight increase of the entire container.

[0028] The pyrolyzable water-discharging substance is not particularly limited as long as it can release water molecules by pyrolysis. Examples include bicarbonates such as sodium bicarbonate, potassium bicarbonate, and ammonium bicarbonate, and ammonium carbonate. These exemplary substances can be used alone or in any combination as the pyrolyzable water-discharging substance. These carbonates can also release water molecules when releasing carbon dioxide, and can improve the fluidity of proteins. Among these, ammonium bicarbonate and ammonium carbonate can be used because almost all components evaporate during pyrolysis, making it difficult for them to remain in the molded parts, thereby reducing the influence on the properties of the molded parts. Furthermore, based on the fact that the greater the weight of water (Pw) released during pyrolysis compared to the weight of the pyrolyzable water-discharging substance, the greater the effect on the fluidity of the protein during molding, ammonium bicarbonate and ammonium carbonate can also be used.

[0029] The pyrolyzable water-discharging substance can be mixed with the protein in any proportion, but the water generated by pyrolysis can also be captured (absorbed) by the protein. Therefore, although the composition for molding of the present disclosure may contain a third component such as an additive, the protein content of the composition for molding excluding the pyrolyzable water-discharging substance should be 50 parts by weight or more so that the properties of the protein itself are not impaired after molding.

[0030] Fibroin can be used as the protein. Among the materials called fibroin, in particular, bio-based polymer materials composed of amino acids such as silk fibroin purified from silkworm cocoons, hornet silk produced by wasp larvae, and spider silk produced from spider webs are particularly useful due to their strong hydrophilicity. One or a mixture of multiple types among these may be used.

[0031] The molecular weight of this protein can be 30 kDa or more and 300 kDa or less. If the molecular weight of the protein is less than 30 kDa, the mechanical strength of the molded part may decrease, which is not preferable. Also, if the molecular weight of the protein is greater than 300 kDa, the viscosity of the material itself becomes too high, so the fluid effect by water becomes small, which is not desirable.

[0032] [Method for manufacturing a composition for molding]

[0033] This manufacturing method consists of a process of preparing an aqueous protein solution, a process of mixing a thermally decomposable drainage substance into the aqueous protein solution, a process of removing moisture from the mixed aqueous solution, and a process of treating it as a composition for molding. Hereinafter, each process will be described.

[0034] An exemplary process for molding a powder is provided in FIG. 4. In step S21, the composition prepared as described in this specification is put into a mold. In step S22, this composition is compressed with a piston during heating.

[0035] [Process for preparing an aqueous protein solution]

[0036] The aqueous protein solution can be produced, for example, by the process for producing a silkworm silk aqueous solution described in International Publication No. 2006 / 101223 or the process for producing a spider silk aqueous solution described in U.S. Patent No. 5245012. By using these, an aqueous solution in which a hydrophilic protein is uniformly dissolved can be obtained. If the viscosity of the aqueous solution is high, the thermally decomposable drainage substance mixed in the next process is difficult to be uniformly mixed. Therefore, the protein concentration in the aqueous solution can be 2 parts by weight or more and 30 parts by weight or less. The weight concentration of the protein can be determined by TGA. Specifically, the weight concentration of the protein is measured by heating 20 - 100 mg of the well-stirred aqueous solution at a heating rate of 10 °C per minute from 30 °C to 120 °C. Next, it is held at 120 °C for 30 minutes to evaporate the moisture and complete the measurement. The ratio of the final weight to the weight at the start of the measurement is taken as the weight concentration of the protein.

[0037] [Mixing treatment of pyrolyzable drainage substances]

[0038] Next, the protein aqueous solution prepared by the above process is mixed with a substance that generates moisture during pyrolysis (pyrolyzable drainage substance). By dissolving both the protein and the pyrolyzable drainage substance in water, the pyrolyzable drainage substance can be uniformly dispersed in the aqueous solution. In the next process, by removing moisture from this aqueous solution, mixing unevenness is reduced, so that both the protein and the pyrolytic drainage material can be dissolved in moisture.

[0039] [Dehydration treatment]

[0040] In this process, a dried body of the mixture is produced by removing moisture from the aqueous solution prepared in the previous process. As a method for removing moisture, methods such as freeze-drying, spray-drying, vacuum-drying, vibration-drying, drum-drying, air-drying, etc. can be used, and these can be combined. Among these, freeze-drying, which has a small effect of heat on the mixture, or spray-drying in which the solution is heated for a short time, can have further advantages.

[0041] When using the freeze-drying method, the freezing temperature is not particularly limited as long as the aqueous solution freezes. However, since the freezing point of an aqueous solution in which a solute is dissolved is lower than that of water, the freezing temperature can be -10°C or lower, or -20°C or lower. The temperature during vacuum drying after freezing can be 20°C or lower so as to have less impact on the thermally decomposable drainage substances, or it can be 10°C or lower or 0°C. On the other hand, since the lower the drying temperature, the more time it takes for dehydration, drying can be carried out at -20°C or higher, or -15°C or higher. In a sufficiently frozen sample, there is no problem as long as the pressure is 600 Pa or lower, which is the pressure at the triple point of water. However, if the sample partially liquefies due to temperature unevenness and the aqueous solution foams, the pressure can be 100 Pa or lower, or 50 Pa or lower. When the temperature of the dried product after removing moisture reaches 10°C or higher, the vacuum can be released. If it is lower than this, condensation occurs inside the sample and the dried product absorbs moisture, which may cause gelation of proteins and the like, so this is not desirable.

[0042] When using spray drying, the protein concentration of the aqueous solution may be adjusted in advance to make spraying easier. By adjusting the air pressure and flow rate of the spray, the time for which the thermally decomposable drainage substances are exposed to heat can be shortened as much as possible. When the heating of the device during spraying leads to heating of the thermally decomposable drainage substances, spraying can be carried out while cooling the periphery of the device with a cooling device or the like.

[0043] [Processing process of the composition for molding]

[0044] The composition obtained by removing moisture can be used as it is as a composition for molding, or it can also be processed into various forms and used as a composition for molding. The processing process is not particularly limited, and examples include pelletization, sheeting, powdering, and flaking. For example, a bulk dried product after freeze-drying can be pulverized using a jet mill, hammer mill, ball mill, pin mill, etc. to produce a powdery composition for molding. Further, after pulverization, classification can be performed to obtain a powdery material with a uniform particle size. Furthermore, a pellet-like material can be obtained by cutting the flake-like material extruded in a strand shape and pressing the flake-like material into a shape such as a cylinder at room temperature.

[0045] The effective weight fraction x of the thermally decomposable drainage substance in the composition for molding can be determined from the following formula.

[0046] PABH = (1 - x) × PAB + x × PH

[0047] That is,

[0048] x = (PABH - PAB) / (PH - PAB) ··· (1)

[0049] Here, PABH is the weight change rate of the composition for molding when heat-dried. PAB is the weight change rate of the composition (protein and third component only) from which pyrolyzable drainage substances are removed from the composition for molding when heat-dried, and PH is the weight change rate of the pyrolyzable drainage substances themselves when heat-dried. If PAB and PH are measured in advance, x can be obtained using Equation (1). For example, in a composition consisting only of a protein with a decomposition start temperature of 200°C and a pyrolyzable drainage substance with a decomposition end temperature of 150°C, without using a third component, when each is heated to 150°C by TGA, PAB and PH can be determined from the weight before and after measurement. Also, when measuring the mixed composition for molding under the same temperature conditions, PABH can be obtained and x can be determined. Also, if the weight ratio after drying the protein is defined as PA, the effective solvent weight ratio y with respect to the weight of the protein can be calculated by the following Equation (2).

[0050] y = x × Pw / PA ··· (2)

[0051] [Molding method for the composition for molding]

[0052] The molding of the composition for molding of the present disclosure can be carried out while decomposing the contained pyrolyzable drainage substances by heat and pressure. Regarding the molding temperature and molding time, based on the decomposition time of the pyrolyzable drainage substances investigated in advance, molding at a higher temperature and for a longer time than that can be executed. Molding at a temperature lower than this may be disadvantageous because substances that generate moisture during pyrolysis are not sufficiently decomposed. Also, molding below the protein degradation start temperature is desired. Furthermore, in order to promote the integration of the molded parts, an appropriate molding time can be selected so that the protein crystallization rate becomes 50% or more.

[0053] The molding method is not particularly limited, and various molding methods such as injection molding, extrusion molding, and compression molding can be used.

[0054] The forming pressure can be 300 MPa or less, and can be 100 MPa or less, similar to the pressure used for forming ordinary thermoplastic resins. Pressures exceeding 300 MPa are not desirable because the equipment load increases in proportion to the size of the formed parts, and the equipment investment cost increases. Also, in order to perform shape transfer, forming can be carried out at 10 MPa or more.

[0055] [Measurement Method of Crystallization Ratio of Formed Parts]

[0056] Regarding the crystallization ratio of the formed parts, refer to the method described in Nature Materials 19, 102 - 108 (2020) and determine it according to the following explanation. Specifically, first, in the range of 1580 cm-1 to 1720 cm-1, measure the infrared absorption spectrum of the surface of the formed parts every 1 cm-1. Calculate the linear function passing through the values of 1580 cm-1 and 1720 cm-1 of the obtained spectrum, set it as the baseline, and subtract it from the measured values. The obtained spectrum is regarded as the sum of the four spectra obtained from the random coil, beta sheet I, beta sheet II, and beta turn, and this is called the effective spectrum.

[0057] On the other hand, the spectrum obtained from the random coil can be approximated by a variable having a peak center between 1645 cm-1 and 1655 cm-1, and the spectra obtained from beta sheet I, beta sheet II, and beta turn can be approximated by the sum of Gaussian functions having peak centers with fixed values of 1620, 1698, and 1685 cm-1, respectively. In the four Gaussian functions, obtain the sum of the peak intensities and deviations of the Gaussian functions as variables, and make this a composite spectrum having nine variables.

[0058] In the range of 1580 cm-1 to 1720 cm-1, the absolute value of the difference between the effective spectrum and the composite spectrum is obtained for each 1 cm-1, and the sum is obtained, which is taken as the spectral error. The error rate is the spectral error with respect to the integral value of the effective spectrum, and the nine variables of the composite spectrum are fitted so that the error rate becomes small. It is assumed that the spectrum converges when the error rate after fitting is 3% or less, and the four spectra constituting the composite spectrum are regarded as the spectra of each actual component. Finally, as the crystallization rate in the present disclosure, the sum of the integral values of the three spectra derived from beta-sheet I, beta-sheet II, and beta-turn with respect to the integral value of the effective spectrum in the range of 1580 cm-1 to 1720 cm-1 is calculated. Since the crystallization rate (total of beta-sheet I, beta-sheet II, and beta-turn) in the case of silk fibroin is less than 20% in the dry state before thermoforming and is considered to be 50% or more after thermoforming, it can be determined that the formed part has strength when the crystallization rate in the present disclosure exceeds 50%.

[0059] Fitting can be performed using software attached to the infrared absorption spectrum measuring device, graph analysis software, a solver add-in in Microsoft Excel software, etc.

[0060] [Shape Transferability Evaluation Method]

[0061] The shape transferability can be evaluated by the Ra of the surface of the molded body when the resin is pressed against a flat mold with a surface roughness Ra (arithmetic mean roughness) of 4 μm. When the Ra of the surface of the molded part is greater than 3 μm, it can be said that the shape transferability is high and the fluidity of the protein is also high. If Ra is 3 μm or less, it can be determined that the transfer rate is low. Note that Ra can be measured by a contact measurement method using a tactile needle or a non-contact measurement method using a laser or light.

[0062] [Examples]

[0063] [Example 1]

[0064] [Step 1: Step of preparing an aqueous protein solution]

[0065] In this step, an aqueous protein solution composed of silk fibroin, a protein derived from animals, was prepared.

[0066] First, the silkworm cocoons were washed with water, then boiled in a 0.02 mol / L aqueous sodium carbonate solution for 30 minutes for degumming. The degummed silk threads were poured into a 9.3 mol / L aqueous LiBr solution and dissolved by stirring at 60°C for 4 hours. Desalting was performed using a 30 / 32 cellulose tube (fractionation molecular weight 12,000 - 14,000) manufactured by Sekisui Chemical Co., Ltd. After further dilution with pure water, it was confirmed by visual inspection that the aqueous solution was uniform without precipitation. This aqueous solution was used as the aqueous protein solution. Thermal analysis of 73.157 mg of the aqueous solution was performed using TGA (TGA 8000 manufactured by PerkinElmer). After heating from 30°C to 120°C at a heating rate of 10°C / min, continuous heating at 120°C for 30 minutes, it became 4.511 mg. From this, it was found that the weight concentration of the protein was 6.17%. Then, it was further heated to 400°C at a heating rate of 1°C / min, and the decomposition start temperature was determined from the weight loss curve. The decomposition start temperature was 185°C. Furthermore, the molecular weight of the protein was measured by SDS-PAGE. For the detailed procedure of SDS-PAGE, the procedure disclosed in L S Wray et al., "J Biomed Mater Res B Appl Biomater", October 2011, 99(1), pages 89 - 101 was used. The molecular weight obtained by this method was 155 kDa.

[0067] [Step 2: Step of mixing pyrolyzable drainage substances]

[0068] In this step, ammonium bicarbonate was selected as the pyrolyzable drainage substance, and a mixed solution with the aqueous protein solution was prepared.

[0069] First, to confirm the temperature suitable for thermal decomposition, 7.108 mg of ammonium bicarbonate (special grade, manufactured by Kishida Chemical Co., Ltd.) was heated from 30°C to 100°C at a heating rate of 10°C / min using TGA 8000, then held at 100°C for 30 minutes, and the weight loss was measured. As a result, it was first revealed that the weight decreased by 0.75 parts by weight at 50°C. Thereby, it was confirmed that ammonium bicarbonate is almost stable at room temperature. After that, after starting to maintain at 100°C, the sample weight became zero in 2 minutes and 35 seconds. Thereby, it was confirmed that it is a material that completely gasifies when heated at 100°C or higher for 3 minutes or more.

[0070] Also, 5.3 g of ammonium bicarbonate was placed in a glass container, sealed, heated at 100°C for 30 minutes, then returned to room temperature, the seal was removed, and the generated gas was removed. As a result, a water film at the bottom of the container could be confirmed, and the container weight increased by 1.2 g. Thus, the weight percentage of available water (Pw) from ammonium bicarbonate was 22.1 parts by weight, and it was confirmed that this was consistent with the calculated value from the molecular formula.

[0071] Ammonium bicarbonate was mixed and stirred so that it would be 6 parts by weight with respect to the protein whose weight concentration was measured in the previous step. One hour after mixing, the mixed aqueous solution was visually confirmed, but no precipitation was observed and it was homogeneous.

[0072] [Step 3: Dehydration step]

[0073] In this step, water was removed from the aqueous solution.

[0074] In Step 2, the solution mixed with ammonium bicarbonate and the protein aqueous solution not mixed with ammonium bicarbonate obtained in Step 1 were each spread on separate trays to a thickness of 5 mm. After that, the trays were placed on the shelves in a freeze dryer (manufactured by Tokyo Rika Kikai Co., Ltd., model number FD-550P) and cooled to -30°C. After 3 hours, after visually confirming the freezing, the pressure was reduced to -6°C at 30 Pa to start dehydration. After 24 hours, the sample temperature was raised to 15°C, the pressure was released, and a sheet-like dried product was taken out. After one week of aging, the two types of sheets remained visually in the same state, and no gelation or the like occurred.

[0075] [Step 4: Step for confirming the composition for molding]

[0076] Based on the thermal decomposition results of Step 2, the molding temperature and molding time in the next step were assumed to be 120°C and 5 minutes, respectively.

[0077] After heating ammonium bicarbonate alone, the protein sheet without ammonium bicarbonate obtained in Step 3 and the protein sheet containing ammonium bicarbonate with a heating rate of 60°C / min were heated from 30°C to 120°C / min, held at a temperature of 120°C / min for 3 minutes, and then the weight change was measured using TGA. After analyzing the measurement results, the weight ratios after measurement were 0.0, 0.915, and 0.866, respectively. These values were used as PH, PAB, and PABH in Equation (1). From this, the proportion x of ammonium bicarbonate could be calculated to be 5.4 parts by weight.

[0078] [Step 5: Step for molding]

[0079] In this step, the protein sheet containing ammonium bicarbonate obtained in Step 4 was molded using a mold with a rough surface.

[0080] First, 1 cm² of the lower piston 1 having a rough surface 2 was prepared. When the surface roughness was measured non - contact using a 10×LT objective lens set on OPTELICS HYBRID+ manufactured by Lasertec Corporation, Ra was 4.0 μm. Using this piston 1 as the lower mold, it was assembled with a piston guide 4 having a 1 cm² prismatic through - hole as shown in Fig. 1 and a piston 3 of 1 cm² without surface roughening as the upper mold, and a compressed body mixed with a thermally decomposable drainage substance 5 (composition for molding) was placed in the mold.

[0081] The mold was set in a mold compression molding machine (VN02 - 2020C manufactured by Mikado Technos Co., Ltd.) whose press plate was pre - heated to 120°C in advance, and the mold was heated and compressed with a load of 10 kN, and the molding pressure was set to 100 MPa. After 5 minutes, the load was released and air - cooled. When it was cooled to 40°C, the mold was disassembled and the molded body was taken out.

[0082] [Step 6: Step for evaluating the crystallization rate]

[0083] In order to calculate the crystallization rate of the molded body from the infrared absorption spectrum, the infrared absorption spectrum of the surface of the molded part was measured by the ATR method using an FT - IR / NIR spectrometer Frontier manufactured by PerkinElmer. When this spectrum was measured by the crystallization rate measurement method and the crystallization rate was obtained, it was 52.1%, and it was confirmed that the crystallization rate was progressing.

[0084] [Step 7: Step for evaluating the shape transferability]

[0085] When the surface roughness of the molded body was measured, Ra was 3.4 μm, and it was confirmed that the transfer was sufficient.

[0086] [Example 2]

[0087] In Step 2 of Example 1, a process similar to Example 1 was carried out, except that an aqueous solution was prepared such that ammonium bicarbonate was 20 parts by weight relative to the protein. The percentage x of ammonium bicarbonate in the composition obtained in Step 4, the water content in the composition for molding, the crystallization rate of the molded part, and the Ra of the surface of the molded part were as shown in the table provided in FIGS. 2A - D.

[0088] [Example 3]

[0089] In Step 2 of Example 1, a process similar to Example 1 was carried out, except that an aqueous solution was prepared such that ammonium bicarbonate was 100 parts by weight relative to the protein. The percentage x of ammonium bicarbonate in the composition for molding, the crystallization rate of the molded part, and the Ra of the surface of the molded part were as shown in the table provided in FIGS. 2A - D.

[0090] [Comparative Example 1]

[0091] Using the dry protein obtained in Step 3 of Example 1 without mixing ammonium bicarbonate, the molding process of Step 5 was carried out. The Ra of the surface in the case of the obtained molded part was as shown in the table provided in FIGS. 2A - D.

[0092] [Example 4]

[0093] After preparing an aqueous protein solution in the same manner as in Step 1 of Example 1, sodium bicarbonate was selected as the pyrolyzable drainage substance in Step 2. Using TGA8000, 9.176 mg of sodium bicarbonate (special grade, manufactured by Kishida Chemical Co., Ltd.) was heated from 30 °C to 150 °C at a heating rate of 10 °C per minute, maintained at 150 °C for 30 minutes, and finally the weight loss from 150 °C to 400 °C was measured at a heating rate of 10 °C per minute. As a result of the measurement, the weight loss at 50 °C was 0.67 parts by weight, and it was confirmed that it was stable at room temperature. Furthermore, it became clear that the sample weight became stable in 3 minutes and 27 seconds after starting to maintain at 150 °C. After that, the weight was stable up to 400 °C, and the final weight was 62.9% of the initial weight. This was almost consistent with the 63.1% residual amount of sodium carbonate assumed in the decomposition reaction formula, and it was confirmed that it was a substance that completed decomposition at 150 °C or higher for 5 minutes or more. Thus, the weight percentage (Pw) of available water from sodium bicarbonate was set to 10.7 parts by weight according to the decomposition reaction formula.

[0094] Sodium bicarbonate was mixed and stirred to be 10 parts by weight with respect to the protein, and its weight concentration was measured in the previous step. One hour after mixing, the liquid mixture was visually confirmed, and no precipitation was observed and it was homogeneous.

[0095] After performing the same process as in Step 3 of Example 1, the percentage c of sodium bicarbonate was calculated in Step 4. Step 5 was carried out with the molding temperature set at 170 °C, and when the Ra of the surface of the obtained molded part was measured, it was as shown in the table shown in FIGS. 2(a) to (D).

[0096] [Example 5]

[0097] The same process as in Example 4 was carried out except that sodium bicarbonate was mixed and stirred to be 100 parts by weight with respect to the protein. The Ra of the surface of the obtained molded part was as shown in the table provided in FIGS. 2A to D.

[0098] [Comparative Example 2]

[0099] To 1.9 g of the dried protein obtained in the dehydration step of Step 3 of Example 1, to which ammonium bicarbonate was not mixed, 0.2 g of water was added at room temperature. Since the amount of water was very small, the dried protein had a non-uniform wetting pattern and water could not be uniformly applied. This mixture was poured into a mold and molded in the same manner as in Step 5 of Example 1. The Ra of the surface of the obtained molded part was as shown in the table provided in FIGS. 2A to 2D.

[0100] [Comparative Example 3]

[0101] To 1.4 g of the dried protein obtained in the dehydration step of Step 3 of Example 1, to which ammonium hydrogen carbonate was not mixed, 0.5 g of water was added at room temperature. When it was mixed with a stirring rod, an adhesive gelatinous mixture was obtained. This mixture was poured into a mold and molded in the same manner as in Step 5 of Example 1. The Ra of the surface of the obtained molded part was as shown in the table provided in FIGS. 2A to 2D.

[0102] [Comparative Example 4]

[0103] To 1.4 g of the dried protein obtained in the dehydration step of Step 3 of Example 1, to which ammonium bicarbonate was not mixed, 0.5 g of water was added at room temperature. Ethanol seemed to be mixed with the protein in the visual inspection. This mixture was poured into a mold and molded in the same manner as in Step 5 of Example 1, but the molded body was brittle. This may be due to the removal of water required for crystallization from the surface by ethanol.

[0104] [Example 6]

[0105] In this example, high-molecular-weight silkworm silk was used. Specifically, by shortening the boiling purification time in Step 1 of Example 1, an aqueous protein solution with a weight concentration of 6.21% composed of silk fibroin with a molecular weight of 201 kDa was prepared.

[0106] [Example 7]

[0107] By adding starch to the aqueous solution prepared in Step 1 of Example 1, a liquid mixture of protein and starch was prepared. Specifically, using a 1 wt% aqueous starch solution (manufactured by Kishida Chemical Co., Ltd., production type 910-00564), mixing and stirring were performed so that the starch content was 100 parts by weight with respect to the protein. Steps 2 to 7 were performed in the same manner as in Example 2. The Ra of the surface of the obtained molded part was as shown in the table provided in FIGS. 2A to D.

[0108] [Example 8]

[0109] In this example, an aqueous protein solution composed of hornet silk was prepared.

[0110] In Step 1, first, cocoons collected from a wasp nest were cut into pieces about 5 mm in size, and impurities were removed to the extent that they could be visually confirmed. The cocoon pieces were placed in a 9 mol / L aqueous LiBr solution and stirred at 40 °C for 1 hour to dissolve the cocoon pieces. The stirred aqueous LiBr solution was centrifuged to separate and remove impurities, which were insoluble components.

[0111] Next, the aqueous LiBr solution from which impurities had been removed was placed in a 30 / 32 cellulose tube (fractionation molecular weight 12,000 to 14,000) manufactured by Sekisui Chemical Co., Ltd. and dialyzed in distilled water at room temperature for 4 days to remove LiBr. When the obtained protein concentration and fractionation molecular weight were confirmed, they were 6.51 parts by weight and 45 kDa, respectively.

[0112] From Step 2 onwards, the steps were carried out in the same manner as in Example 2 to produce a molded part, and the Ra of the surface of the obtained molded part was made as shown in the table shown in FIGS. 2(a) to (D).

[0113] [Definitions]

[0114] In this description, specific details are set forth in order to provide a thorough understanding of the disclosed examples. In other instances, well-known methods, procedures, components, and circuits are not described in detail so as not to unnecessarily extend the present disclosure.

[0115] When an element or a part is referred to in this specification as being "on," "to," "connected to," or "coupled to" another element or part, it should be understood that it may be directly on, directly to, directly connected to, or directly coupled to the other element or part, or intervening elements or parts may be present. In contrast, when an element is referred to as being "directly on," "directly connected to," or "directly coupled to" another element or component, no intervening elements or components are present. When used, the term "and / or" includes any and all combinations of one or more of the associated listed items, as so provided.

[0116] Spatially relative terms such as "under," "above," "upper," "proximal," "distal," etc. may be used in this specification to facilitate descriptions of the relationship of one element or feature to another element or feature as shown in the various figures. However, it should be understood that spatially relative terms are intended to encompass different orientations of the device during use or operation in addition to the orientation shown in the figures. For example, if the device in the figure is turned over, an element described as "under" or "beneath" another element or feature will be oriented "above" the other element or feature. Thus, relative spatial terms such as "below" can encompass both upward and downward orientations. The device may be in other orientations (rotated 90 degrees or otherwise), and the spatially relative descriptors used in this specification should be interpreted accordingly. Similarly, the relative spatial terms "proximal" and "distal" may also be interchangeable where applicable.

[0117] The term "about" as used in this specification means, for example, within 10%, within 5%, or less. In some embodiments, the term "about" may mean within the measurement error.

[0118] Terms such as first, second, third, etc. may be used herein to describe various elements, components, regions, parts, and / or sections. It should be understood that these elements, components, regions, parts, and / or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, part, or section from other regions, parts, or sections. Thus, a first element, component, region, part, or section discussed below could be termed a second element, component, region, part, or section without departing from the teachings of this specification.

[0119] The terms used in this specification are for the purpose of describing particular embodiments only and are not intended to be limiting. The use of the terms "a", "an", and "the", and similar referents in the context of describing the present disclosure (especially in the context of the following claims), unless otherwise indicated herein or clearly contradicted by the context, should be construed to cover both the singular and the plural forms. The terms "comprising", "having", "includes", "including", and "containing" are to be construed as open-ended terms (i.e., meaning "including, but not limited to") unless specifically stated otherwise. Specifically, when these terms are used in this specification, they specify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof that are not explicitly stated. The recitation of numerical ranges herein is intended, unless otherwise specifically indicated herein, merely as a shorthand way of referring individually to each separate value falling within the range, and each separate value is incorporated into the specification as if it were individually recited herein. For example, if the range 10-15 is disclosed, then 11, 12, 13, and 14 are also disclosed. All methods described herein can be performed in any suitable order, unless otherwise indicated herein or clearly contradicted by the context. The use of any and all examples, or exemplary language (e.g., "such as") provided herein is intended merely to better illuminate the disclosure and does not impose a limitation on the scope of the disclosure unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the disclosure.

[0120] The methods and compositions of the present disclosure can be incorporated in various embodiments, and it will be understood that only a few of these can be disclosed herein. Variations of these embodiments may become apparent to those skilled in the art upon reading the above description. The inventors expect those skilled in the art to employ such appropriate variations, and the inventors intend the disclosure to be practiced otherwise than as particularly described herein. Accordingly, the present disclosure includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Further, any combination of the above elements in all possible variations thereof is included in the disclosure unless otherwise indicated or otherwise clearly contradicted by context.

Claims

1. Heating a molding composition comprising a pyrolyzable drainage material that decomposes by pyrolysis to generate water molecules and fibroin; applying pressure to mold the composition while pyrolyzing the pyrolyzable wastewater material; A method for producing a molded body, comprising the steps of:

2. The method for producing a molded body according to claim 1 , wherein the crystallization rate of the fibroin in the molded body is 50% or more.

3. The method for producing a molded body according to claim 1, wherein the molding temperature in the molding process is T1 or more and T1+100°C or less, and the initiation temperature of the thermal decomposition of the thermally decomposable wastewater material is T1.

4. The method for producing a molded body according to claim 1 , wherein a molding pressure in the molding process is from 10 MPa to 300 MPa.

5. Obtaining an aqueous solution in which the thermally decomposable wastewater material and fibroin are dissolved; obtaining said composition by removing water as a solvent from said aqueous solution; The method for producing a molded article according to claim 1 , wherein the composition is obtained by a method comprising the steps of:

6. The method for producing a molded article according to claim 5 , wherein a concentration of the fibroin in the aqueous solution is 2 parts by weight or more and 30 parts by weight or less with respect to water as the solvent.

7. The method for producing a molded body according to claim 5 , wherein the water as the solvent is removed from the aqueous solution by freeze-drying or spray-drying.

8. The method for producing a molded body according to claim 1 , wherein the thermally decomposable wastewater material contains at least one of sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, and ammonium carbonate.

9. The method for producing a molded article according to claim 1, wherein the amount of water generated from the pyrolytic wastewater material during pyrolysis is 1 part by weight or more and 50 parts by weight or less relative to the fibroin.

10. The method for producing a molded article according to claim 1, wherein the fibroin comprises silkworm silk and / or a derivative thereof.

11. The method for producing a molded body according to claim 1, wherein the molecular weight of the fibroin is 30 kDa or more and 300 kDa or less.

Images