Method for preparing cocoons for silk reeling

Abstract

To provide a novel method for boiling cocoons without having to apply high-temperature heat treatment to a silk yarn, and which does not require a basic solution.SOLUTION: The method for preparing a silk reeling cocoon comprises: a contact step for making the cocoon contact an organic solvent and / or an organic acid; and an infiltration step for making water infiltrate into a cocoon layer and a cocoon cavity after the contact step.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for preparing a cocoon for reeling, the cocoon for reeling prepared thereby, and a method for producing raw silk. [Background technology]

[0002] The use of biological materials has attracted more attention as genetic manipulation and genomic information have become easier to use, and is currently expanding. Research and development into such materials is being actively conducted not only in the development of pharmaceuticals using cells, but also in the field of materials.

[0003] Silk thread, which is one of the biological materials, is an ideal material as the basis for developing new materials from the viewpoints of its strength, texture, manufacturing method, processing method, etc. In fact, many studies have been conducted to impart new functions to silk thread (Patent Document 1 and Non-Patent Document 1).

[0004] Conventional silk manufacturing methods include several steps involving heating, such as drying, boiling cocoons, and degumming. In recent years, attempts have been made to add various proteins to silk threads using recombinant gene technology in order to impart new functions to the silk threads. However, problems have arisen in that the added proteins are thermally denatured during the heating process, causing them to lose their functions. There is an increasing need to develop new methods that do not inactivate the added proteins.

[0005] Cocoon boiling is a process in which cocoons are boiled to make it easier to pull out the thread (cord). Conventionally, this process required boiling the cocoons in hot water. The present inventors have developed a method of treating cocoons at a low temperature of about 60°C using a basic solution as a method that can be carried out at a relatively low temperature that does not denature proteins (Patent Document 2). This method has the problem that it is not suitable for proteins that are easily denatured in a basic environment because it exposes the cocoons to a basic environment for a relatively long period of time. Therefore, there has been a demand for the development of a method that can be carried out at a lower temperature without inactivating the added functional protein. [Prior art documents] [Patent documents]

[0006]

Patent Document 1

Patent Document 2

Non-Patent Document

[0007]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] An object of the present invention is to provide a novel cocoon cooking method that does not require high-temperature heat treatment of silk thread and does not require a basic solution.

Means for Solving the Problems

[0009] The present inventors conducted intensive studies to solve the above problems. As a result, by bringing cocoons into contact with an organic solvent or an organic acid, it was found that it is possible to prepare cocoons that can be reeled at a temperature lower than that of the conventionally developed methods, particularly at room temperature, without denaturing the proteins added to the silk thread. Furthermore, when this method was applied to silk thread containing a functional region, it was revealed that the activity of the functional region was maintained. In addition, as a result of the treatment with an organic solvent or an organic acid significantly promoting water penetration, it was found that even when cooking cocoons at a conventional temperature using ordinary cocoons, the same effect can be obtained in a shorter time than before. The present invention is based on the above novel findings and provides the following.

[0010] (1) A method for preparing cocoons for reeling, comprising a contact step of bringing cocoons into contact with an organic solvent and / or an organic acid, and a penetration step of allowing water to penetrate into the cocoon layer and the cocoon cavity after the contact. (2) The preparation method according to (1), further comprising a removal step of removing the organic solvent and / or organic acid before the penetration step. (3) The preparation method according to (1) or (2), wherein the penetration step is performed by an immersion method. (4) The preparation method according to (1) or (2), wherein the penetration step includes a step of reducing the pressure inside the cocoon cavity to reduce the pressure inside the cocoon cavity. (5) The preparation method according to (4), wherein the penetration step is performed by a method selected from the group consisting of a low-temperature decompression method, a cocoon boiling and cooling method, and a touch steaming method. (6) The preparation method according to any one of (1) to (5), wherein the organic solvent includes one or more organic solvents selected from the group consisting of lower alcohols, acetone, N,N-dimethylformamide, acetonitrile, and ethyl acetate. (7) The preparation method according to any one of (1) to (6), wherein the organic acid includes acetic acid and / or propionic acid. (8) A cocoon for reeling prepared by the preparation method according to any one of (1) to (7). (9) A method for producing raw silk, comprising a reeling step of performing reeling on a cocoon for reeling obtained by the preparation method according to any one of (1) to (7), and a reeling step of performing reeling based on the thread end obtained in the reeling step.

Advantages of the Invention

[0011] According to the present invention, a cocoon for reeling can be prepared at a temperature at which the protein does not denature. According to the present invention, a cocoon for reeling can be prepared in a short time. Further, according to the production method of the present invention, raw silk can be produced from the prepared cocoon for reeling.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

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Figure 5

Embodiments for Carrying out the Invention

[0013] 1. Method for Preparing Cocoons for Reeling 1-1. Overview The first aspect of the present invention is a method for preparing cocoons for reeling. The method of this aspect includes a contact step and a penetration step as essential steps. According to the method of this aspect, cocoons for reeling can be prepared at a lower temperature or in a shorter time.

[0014] 1-2. Definitions "Reeling" refers to the process of producing raw silk by drawing silk from the silk opening of a reeled cocoon. In this specification, "cocoon" refers to an object composed of a cocoon layer, an adult, a pupa, a molted shell, and / or a larva. The cocoon in this specification includes cocoons made by any silk-producing insect as long as the cocoon layer is composed of silk.

[0015] In this specification, "reeling cocoon" refers to a cocoon processed so that the silk opening can be easily drawn out by reeling. Usually, the reeling cocoon has a structure in which the cocoon cavity is filled with water and the cocoon itself cannot be pulled up during reeling.

[0016] In this specification, "cocoon cavity" refers to the space inside the cocoon, that is, the pupal chamber. For example, in the case of a silkworm cocoon, it means the space in which the silkworm larva, pupa, or adult is housed.

[0017] In this specification, "cocoon layer" refers to the wall part of the cocoon composed of silk. "Reeling" refers to the process of searching for and drawing out the silk opening from the cocoon. Usually, it is carried out with a reeling broom or the like, but the reeling in this specification includes any process in which the silk opening is drawn out from the reeling cocoon regardless of the means.

[0018] In this specification, "silk opening" refers to the end of the silk that has become free from the cocoon. In this specification, "silk" refers to silk derived from silk-producing insects, and refers to protein-based silk made by silk-producing insect larvae or adults for the purpose of building nests, moving, fixing, making cocoons, capturing food, etc. The silk in this specification includes silk derived from any silk-producing insect.

[0019] In this specification, "silk-producing insect" refers to a general term for insects that have silk glands and can spin silk. Usually, it refers to species that can spin silk for the purpose of building nests, making cocoons, or moving during the larval stage.

[0020] In this specification, "raw silk" refers to silk from which cocoons have been reeled and in which adhesive substances such as sericin remain. The raw silk in this specification includes not only simply reeled silk but also combined silk and / or twisted silk.

[0021] In this specification, the "organic solvent" refers to an organic compound that is in a liquid form at normal temperature and pressure.

[0022] In this specification, the "lower alcohol" refers to an organic compound having 4 or fewer carbon atoms and having a hydroxy group and its derivatives. The lower alcohols in this specification include both straight-chain lower alcohols with an unbranched carbon chain and branched-chain lower alcohols with a branched carbon chain.

[0023] In this specification, the "organic acid" refers to an organic compound that can donate a proton to another compound. The organic acid in this specification mainly refers to an acidic organic solvent that is liquid at normal temperature and pressure.

[0024] "Contact" means that one substance physically touches another substance directly. "Penetration" means that a liquid existing outside a substance or space moves inside through the surface of the substance or the structure surrounding the space. For example, "penetrating into the cocoon layer" means that the liquid outside the cocoon soaks into the cocoon layer, and "penetrating into the cocoon cavity" means that the liquid outside the cocoon moves into the cocoon cavity through the cocoon layer.

[0025] "Removal" means causing at least a part of a specific substance contained in a structure to be lost from the structure. The removal in this specification includes both actively removing a specific substance and passively removing it by placing it in a situation where the specific substance can be lost.

[0026] In this specification, "immersion" means immersing part or all of the target substance in a liquid. In this specification, "reducing pressure" means reducing the atmospheric pressure or vapor pressure. The reduction of pressure in this specification includes both directly reducing the atmospheric pressure or vapor pressure and indirectly reducing them due to temperature changes or the like.

[0027] 1-3. Structure The method of this aspect includes a contacting step and a penetration step as essential steps, and includes a drying step, a removing step, and a washing step as optional steps.

[0028] 1-3-1. Drying Step The "drying step" is an optional step and is a step of drying the cocoon and / or the pupa in the cocoon cavity to prepare a dried cocoon.

[0029] This step is usually carried out for the purpose of killing the pupa in the cocoon cavity and / or long-term preservation. Therefore, the necessity of this step can be determined by considering conditions such as the cocoon to be used and the necessity of preservation. For example, when using a cocoon that does not contain a pupa in the cocoon cavity or when not storing, this step may not be performed.

[0030] The drying method used in this step is not particularly limited. For example, a method used for drying raw cocoons of silkworms can be used. Specifically, for example, air-heat drying such as hot air drying, natural drying such as sun drying, drying by infrared rays, vacuum drying using a vacuum pump or the like in a container to degas and evaporate, freeze drying in which moisture is vaporized while frozen, air drying method using warm air or cold air, dehumidifying drying method using a dehumidifying agent or the like, drying by electromagnetic waves or a combination thereof, etc. can be mentioned. Any method can be carried out manually or automatically using a machine or the like.

[0031] Additional treatment can be performed on the cocoon along with drying. For example, when performing natural drying, the cocoon may be frozen or refrigerated before and after that.

[0032] 1-3-2. Contacting Step The "contacting step" is an essential step and is a step of bringing the cocoon into contact with an organic solvent and / or an organic acid (hereinafter, in this specification, often collectively referred to as "organic solvent etc."). When performing the drying step, this step can be carried out thereafter.

[0033] <Cocoon> The cocoon used in this step is not particularly limited. For example, it can be arbitrarily selected according to the origin insect, its composition, and the purpose.

[0034] The silkworm from which the cocoon is derived is not particularly limited, but preferably a species belonging to the order Lepidoptera that can spin a large amount of silk. For example, species belonging to the family Bombycidae, Saturniidae, Brahmaeidae, Eupterotidae, Lasiocampidae, Psychidae, Archtiidae, Noctuidae, etc. are preferred as the silkworms in this specification. Species belonging to the genera Bombyx, Samia, Antheraea, Saturnia, Attacus, Rhodinia, specifically, Bombyx mori (domestic silkworm: hereinafter, in this specification, both the larvae and adults of the domestic silkworm are collectively referred to as "domestic silkworm"), Bombyx mandarina, Samia cynthia (including Samia cynthia ricini and hybrids of Samia cynthia and Samia cynthia ricini), Antheraea yamamai, Antheraea pernyi (tussah silkworm), Saturnia japonica, Actias gnoma, etc. are particularly preferred. In addition, their recombinants and mutants obtained by genome editing, etc. can be used. The cocoon used in this method may be derived from a single individual, or a mixture derived from multiple individuals or multiple species.

[0035] When using a cocoon derived from a recombinant, the cocoon may be composed of recombinant silk.

[0036] In this specification, "recombinant silk" refers to silk in which a genetic recombination operation has been performed on the gene of the silk component. Recombinant silk includes not only silk in which sericin or fibroin constituting the silk has been genetically modified, but also silk in which the internal structure has changed by genetic recombination, silk in which the properties have changed by genetic recombination, etc. Recombinant silk can contain, for example, a functional region.

[0037] As used herein, the "functional region" refers to a protein region introduced into silk by genetic recombination to impart a desired function. In this specification, silk into which a functional region has been introduced is referred to as "functional silk" or the like. "Functionally possible" means that the functional region exhibits activity.

[0038] The types of functional regions are not particularly limited and include any protein or a portion thereof. For example, binding proteins such as enzymes, antibodies, receptors, ligands, etc., neuropeptides, hormones, fluorescent proteins, luminescent proteins, and portions thereof can be mentioned.

[0039] For example, fluorescent proteins include GFP, DsRed, TurboRFP and their variants, and various fluorescent proteins having other origins such as azami green.

[0040] The number and types of functional regions are not particularly limited. The silk used in the present invention can contain, for example, one or more of one type of functional region, or a plurality of a plurality of types of functional regions. When a single molecule contains a plurality of functional regions, their arrangement is also not particularly limited. For example, one or a plurality of types of functional regions can be linked to each other at the same position or dispersed and introduced at different positions.

[0041] The functional region to be used can be appropriately selected according to its properties and the like. For example, in the case of a fluorescent protein, azami green has a higher quantum yield than GFP, and stronger fluorescence can be obtained from excitation light of the same intensity. However, in particular, monomeric azami green has properties inferior to GFP with respect to pH stability (Karasawa et al., J. Biol. Chem. 278(36): 34167-71 (2003)).

[0042] The functional region used in the method of the present invention may be a protein or a portion thereof that is easily thermally denatured and / or easily denatured under basic conditions.

[0043] The origin of the functional region is not particularly limited. For example, it may be derived from an endogenous gene of the silkworm or an exogenous gene.

[0044] As used herein, the term "exogenous gene" refers to any gene introduced from the outside. The exogenous genes in this specification include both natural genes and artificial genes. In the case of exogenous genes, the organism from which they are derived is not particularly limited. The types of exogenous genes are not particularly limited. For example, they may be genes not derived from silk, genes derived from silk, or genes that are combinations of them.

[0045] The method of introducing the gene is not particularly limited. It can be introduced using gene recombination techniques known in the art.

[0046] The treatment pre-applied to the cocoon used in this step is not particularly limited. Specifically, for example, the cocoon produced by the silkworm can be used as it is or can be optionally treated prior to this step and then used. Specifically, for example, either raw cocoons or dried cocoons obtained by drying raw cocoons can be used.

[0047] The treatment applied to the silk before this method is not particularly limited, but when the purpose is not to perform high-temperature heat treatment, it is preferable that this step does not include treatment at a high temperature (for example, 80 °C or higher).

[0048] <such as organic solvents> The temperature of the organic solvent or the like is not particularly limited. For example, it can be a temperature equal to or higher than the melting point or equal to or lower than the boiling point of the organic solvent or the like to be used. Specifically, for example, it can be -120°C or higher, -100°C or higher, -90°C or higher, -80°C or higher, -50°C or higher, -30°C or higher, -20°C or higher, -10°C or higher, -5°C or higher, -2°C or higher, -1°C or higher, 0°C or higher, 3°C or higher, 5°C or higher, 10°C or higher, 12°C or higher, 15°C or higher, 17°C or higher, 18°C or higher, 19°C or higher, 20°C or higher, 23°C or higher, 24°C or higher, or 25°C or higher. Also, the specific upper limit of the temperature is, for example, 100°C or lower, 90°C or lower, 80°C or lower, 79°C or lower, 75°C or lower, 70°C or lower, 65°C or lower, 60°C or lower, 55°C or lower, 50°C or lower, 45°C or lower, 40°C or lower, 37°C or lower, 35°C or lower, 33°C or lower, 31°C or lower, or 30°C or lower. The temperature only needs to be generally within the above temperature range during the period of this process and does not need to be kept constant. If necessary, the temperature can be adjusted using refrigeration means, refrigeration means, heat preservation means, heating means, and / or heating means known in the art.

[0049] The type of the organic solvent or the like is not particularly limited. Any water-soluble or water-insoluble organic solvent or the like can be used.

[0050] In this specification, "water-soluble" refers to the property that the solubility in water at one atmosphere and 20°C is greater than a certain value. The solubility of the water-soluble organic solvent or the like is not particularly limited, but for example, it is greater than 8000 mg / L. Specifically, for example, it is 8500 mg / L or higher, 9000 mg / L or higher, 9500 mg / L or higher, 10000 mg / L or higher, 15000 mg / L or higher, 20000 mg / L or higher, 25000 mg / L or higher, 30000 mg / L or higher, 50000 mg / L or higher, 100000 mg / L or higher, 250000 mg / L or higher, 500000 mg / L or higher, or 1000000 mg / L. "Water-insoluble" refers to the property of not being water-soluble.

[0051] Examples of the water-soluble organic solvents include, but are not limited to, lower alcohols, acetone, N,N-dimethylformamide, acetonitrile, carboxylic acid derivatives such as ethyl acetate and formamide, polyhydric alcohols such as ethylene glycol and glycerin, other alcohols such as diethylene glycol, alcohol derivatives such as alcohol ethers and alcohol ether esters, sulfoxides such as dimethyl sulfoxide, polyethers, and lactones.

[0052] Examples of the water-insoluble organic solvents include, but are not limited to, chloroform, isoamyl alcohol (also called isopentyl alcohol), and aromatic compounds such as xylene, benzene, hexane, and toluene.

[0053] In addition, as the organic solvent or the like, for example, a low surface tension solvent may be used. The low surface tension solvent refers to an organic solvent or the like having a surface tension smaller than that of pure water. Since the surface tension of pure water is 72.75 mN / m at 20°C, the surface tension of the low surface tension solvent may be less than 72.75 mN / m (20°C). Specifically, for example, those having a surface tension at 20°C of less than 72.75 mN / m, less than 70 mN / m, less than 65 mN / m, less than 60 mN / m, less than 55 mN / m, less than 50 mN / m, less than 45 mN / m, less than 40 mN / m, or less than 38 mN / m can be used.

[0054] Examples of the organic acids include carboxylic acids including aliphatic carboxylic acids such as formic acid, acetic acid, and propionic acid, and aromatic carboxylic acids such as benzoic acid and salicylic acid, sulfonic acids such as methanesulfonic acid, and acidic alcohols such as phenol and enol.

[0055] The organic solvent etc. does not have to be a pure substance. For example, an inorganic compound such as water and / or a mixture with other organic solvents etc. can be used. In that case, the concentration of the organic solvent etc. is not particularly limited. For example, it is 20% by volume or more, 30% by volume or more, 40% by volume or more, 45% by volume or more, 50% by volume or more, 55% by volume or more, 59% by volume or more, 60% by volume or more, 61% by volume or more, 64% by volume or more, 65% by volume or more, 66% by volume or more, 69% by volume or more, 70% by volume or more, 71% by volume or more, 74% by volume or more, 75% by volume or more, 76% by volume or more, 79% by volume or more, 80% by volume or more, 81% by volume or more, 90% by volume or more, or 99.5% by volume or more with respect to the total volume of the mixture. The concentration only needs to be generally within the above range during this step and does not have to be kept constant. Also, for example, even if an organic solvent etc. or other components are added during this step, or the solution is replaced, it is acceptable.

[0056] In this step, the organic solvent etc. only needs to have at least a part of it in a liquid state. It is not necessary for all of the organic solvent etc. to be maintained in a liquid form during this step. For example, a part of it may be vaporized or solidified during this step. For example, in the case of a pure substance that is not in a liquid form but can become a liquid by mixing with other substances, it may be preferable to use it as a mixture.

[0057] The organic solvent etc. used in the present invention can contain any other components as necessary. Specifically, for example, buffer agents, pH adjusters, surfactants, chelating agents, etc. can be mentioned.

[0058] The liquid amount of the organic solvent etc. is not particularly limited. For example, when the contact is carried out by immersion, in terms of the bath ratio indicating the volume of the entire liquid with respect to the weight of the cocoon layer being 1, it is usually used at a bath ratio of 1:0.5 or more, 1:1 or more, 1:1.5 or more, 1:2 or more, 1:5 or more, or 1:10 or more.

[0059] The conditions such as temperature of the organic solvent etc. can be appropriately selected according to the purpose and the properties of the silk threads constituting the cocoon etc. For example, the temperature of the organic solvent etc. may be determined by the physical properties such as the boiling point and melting point of the organic solvent etc. used. Also, the conditions may be selected according to the purpose. For example, when the purpose is not to perform heat treatment, an organic solvent etc. at a temperature of less than 80°C, less than 60°C, normal temperature (15°C or more and less than 40°C) or at or below normal temperature can be used. When the purpose is to shorten the time, an organic solvent etc. at a high temperature can be used.

[0060] The organic solvent etc. used in this step may be prepared before this step or may be prepared simultaneously with this step. Specifically, for example, components may be added and / or updated during this step.

[0061] <Contact> The method is not particularly limited as long as the solid (cocoon) and the liquid (organic solvent etc.) can be in direct contact with each other. In this step, since both components are brought into contact, a method suitable for the contact between the solid and the liquid is preferred. Specifically, for example, the cocoon can be immersed in the organic solvent etc., or they can be sprayed, injected or applied to the cocoon or a combination thereof to bring them into contact.

[0062] For the contact, for example, known methods used in the cocoon boiling or scouring of silkworm cocoons can be used. Specific methods include manual methods, for example, immersing the cocoon as it is, hanging it on something, or putting it in a bag etc. and immersing it in the liquid, or using a machine to inject the liquid etc. The methods of hanging, putting in a bag etc., and injecting can be carried out according to the methods used in scouring such as the hanging scouring method, the bag scouring method and the injection scouring method respectively. The "hanging scouring method" is a method of immersing a fabric or silk thread in a liquid in a pot while hanging it on a pole or rod passed over or in the pot, and is divided into the pole scouring method, the rod scouring method etc. according to what is used. The "bag scouring method" is a method of putting cocoons or silk threads in a bag such as a cotton bag and immersing it in the liquid. The "injection scouring method" is a method of injecting a liquid onto silk threads by a machine.

[0063] When using the method of immersion, it is not necessary for the whole cocoon to be under the liquid surface at once. For example, by means of repositioning, mixing, rotation, etc., as long as the whole cocoon comes into contact with an organic solvent or the like as a result. Even when using a method other than immersion, it is preferable to perform an operation such that the whole cocoon can come into contact with an organic solvent or the like by repositioning or rotating the cocoon, etc.

[0064] The contact time is not particularly limited as long as the organic solvent or the like can penetrate into the cocoon layer. For example, it can be determined in relation to the temperature and properties of the organic solvent or the like. Generally, the lower the temperature, the longer the time, and the higher the temperature, the shorter the time. Specifically, for example, it is 1 second or more, 3 seconds or more, 5 seconds or more, 6 seconds or more, 9 seconds or more, 10 seconds or more, 11 seconds or more, 15 seconds or more, 20 seconds or more, 25 seconds or more, or 30 seconds or more. In this step, the organic solvent or the like can penetrate into the cocoon cavity.

[0065] The contact can be carried out multiple times. In that case, the composition, contact time, temperature, etc. of the organic solvent or the like may be changed for each contact, or those used in the previous contact may be used as they are.

[0066] 1-3-3. Removal step The "removal step" is an optional step and is a step of removing the organic solvent and / or organic acid from the cocoon layer. This step can be carried out after the contact step.

[0067] The necessity of this step can be determined by considering conditions such as the type and concentration of the organic solvent or the like used in the contact step. Usually, it is carried out when a water-insoluble organic solvent or the like is used in the contact step. Even when an organic solvent or the like containing a water-insoluble organic solvent or the like is used in the contact step, for example, depending on its type, or when the organic solvent or the like contains a water-soluble organic solvent or the like or a surfactant, this step may not be necessary.

[0068] The removal method used in this step is not particularly limited. For example, it can be carried out by drying, dropping, centrifugation, suction, blowing, or a combination thereof, etc.

[0069] When drying, the method is not particularly limited. For example, the method described above can be used in a drying process such as under reduced pressure.

[0070] When dripping, any method can be used as long as it allows the organic solvent or the like to drop off according to gravity, and the method is not particularly limited. For example, the cocoons can be left stationary to allow the organic solvent or the like to drop off. At this time, stimuli such as rotation or vibration may be applied to the cocoons.

[0071] When centrifuging, any method can be used as long as it allows the organic solvent or the like to drop off by utilizing centrifugal force, and the method is not particularly limited. For example, it can be carried out manually or automatically using a centrifuge or the like.

[0072] When sucking, the method is not particularly limited. For example, it can be carried out manually by breathing or using a syringe, or by using a suction machine or the like.

[0073] When blowing air, any method can be used as long as it allows the organic solvent or the like to drop off by utilizing wind pressure, and the method is not particularly limited. For example, it can be carried out manually by breathing or using a fan, or by using a blower or the like.

[0074] This step can be carried out multiple times. In that case, the methods and conditions used may be the same each time or may vary each time.

[0075] 1-3-4. Washing step The "washing step" is an optional step and is a step of washing the cocoons by bringing the silk thread into contact with water, an aqueous solution, or another organic solvent or the like. This step can be carried out after the contact step. Also, when performing the removal step, it can be carried out simultaneously with or after the removal step. In particular, when the present method includes a plurality of steps, this step can be carried out between each of the steps. For example, when performing the drying step, this step may be carried out between the drying step and the contact step and / or after the contact step. When the contact step is carried out multiple times, this step may be carried out between each contact.

[0076] The cleaning liquid used in this process is not particularly limited. For example, surfactants, water-soluble or volatile organic solvents such as toluene, benzene, and ethanol, and water can be used.

[0077] This process can be carried out multiple times. In that case, the composition and temperature of the liquid used may be the same each time or may vary each time.

[0078] 1-3-5. Penetration Process The "penetration process" is an essential process and is a process of allowing water or an aqueous solution to penetrate into the cocoon layer and the cocoon cavity after contact. This process can be carried out simultaneously with or after the contact process, and when performing the removal process, it can be carried out simultaneously with or after the removal process.

[0079] The composition of the aqueous solution used in this process is not particularly limited. For example, the aqueous solution can contain any other components as necessary. Specifically, for example, alkali agents such as sodium carbonate, sodium bicarbonate, and calcium carbonate, acid solutions such as citric acid, acetic acid, and propionic acid, metal ions, buffers, pH adjusters, surfactants, and chelating agents can be mentioned. The water used for cocoon boiling in silkworm cocoons may also be used.

[0080] The temperature of the water and the aqueous solution used in this process is not particularly limited. For example, water at the temperatures exemplified for organic solvents, etc. (including cold water (less than 15°C), normal temperature water (15°C or more and less than 40°C), warm water (40°C or more and less than 80°C), and hot water (80°C or more)) can be used. The temperature of the hot water is not particularly limited, but for example, it is 80°C or more, 85°C or more, 90°C or more, 93°C or more, or 95°C or more.

[0081] The method used in this process is not particularly limited. For example, the method commonly used for boiling silkworm cocoons can be used. For example, this process can be carried out by the immersion method. In this method, the cocoons are immersed in water for a certain period of time. The time at this time is not particularly limited. For example, it can be carried out for 30 seconds or more, 1 minute or more, 1 minute 30 seconds or more, 2 minutes or more, 5 minutes or more, 6 minutes or more, 8 minutes or more, 10 minutes or more, 15 minutes or more, 20 minutes or more, 30 minutes or more, 40 minutes or more, 50 minutes or more, 60 minutes or more, or 90 minutes or more. Other conditions, etc., shall conform to the details described for the immersion in the contact process.

[0082] This process may include a step of reducing the pressure inside the cocoon. In this step, the pressure inside the cocoon is reduced. Since the pressure reduction in this step is carried out for the purpose of assisting the penetration of water into the cocoon, the method used and the degree of pressure reduction are not particularly limited as long as the purpose is achieved.

[0083] Specific methods include, for example, the pressure reduction method, the cooling method, and the contact steaming method, etc. The pressure reduction method is a method of reducing the air pressure in the space containing the cocoons while the cocoons are immersed in water or an aqueous solution. In this method, usually, the pressure is reduced during immersion, and after maintaining the reduced pressure state for a certain period of time, the pressure is restored to atmospheric pressure. In particular, the pressure reduction method carried out using cold water, normal temperature water, or warm water is called the low-temperature pressure reduction method, and the pressure reduction method carried out using hot water is called the high-temperature pressure reduction method.

[0084] The means for changing the air pressure is not particularly limited. For example, methods such as degassing and / or supplying air to the space containing the cocoons (inside a container or in a room, etc.), or methods for changing the volume of the space (especially inside a container), etc. can be mentioned. Commercially available pressure reducers, etc. may be used.

[0085] The degree of pressure reduction is not particularly limited. Usually, it is reduced to a low vacuum (about 10 5 Pa to 10 2 Pa). For example, the gauge pressure indicating the strength of pressure reduction may be -50 mmHg or less, specifically, -750 mmHg to -50 mmHg, -700 mmHg to -100 mmHg, -650 mmHg to -200 mmHg, or -600 mmHg to -300 mmHg.

[0086] The time for maintaining the reduced pressure state is not particularly limited. For example, it can be maintained for the time exemplified in the dipping method.

[0087] After maintaining the reduced pressure state, the pressure is restored to normal atmospheric pressure (e.g., one atmosphere). At this time, it is preferable to restore the pressure at a low speed, but it is not limited thereto. Specifically, for example, the pressure restoration is performed over 1 second or more, 2 seconds or more, 5 seconds or more, 10 seconds or more, 30 seconds or more, 40 seconds or more, 1 minute or more, or 2 minutes or more.

[0088] The cooling method is a method of changing the temperature of the water used for dipping. In this method, after the first dipping in relatively hot water, the second dipping in relatively cold water is performed.

[0089] The temperature difference between the first and second dips is not particularly limited, but for example, it can be changed by 10 °C or more, 15 °C or more, 20 °C or more, 25 °C or more, 30 °C or more, or 35 °C or more. The temperature of each dip is not particularly limited, but for example, it can be appropriately selected from the water temperatures exemplified in this step. In this specification, the method of using hot water for the first dip is called the cocoon boiling and cooling method, and the method of using water at a temperature below warm water for the first dip is called the low-temperature cooling method. For example, as the cocoon boiling and cooling method, hot water can be used for the first dip and warm water can be used for the second dip. The temperature of the hot water used in the cocoon boiling and cooling method can be, for example, 90 °C or more or 95 °C or more.

[0090] The time for performing the first and second dips is not particularly limited. For example, it can be performed for the time exemplified in the dipping method, but according to the method of the present invention, the same effect can be obtained in a shorter time than usual. Therefore, each dip can be sufficiently performed for, for example, 5 minutes or less, 3 minutes or less, 2 minutes or less, or 1 minute 30 seconds or less. The times of the first and second dips may be the same or different from each other. For example, the first dip can be performed longer than the second dip.

[0091] The steaming method is a method of applying high-temperature steam to cocoons instead of the first immersion in the cooling method. The temperature of the steam may be, for example, the temperature of the hot water used in the cooling method.

[0092] Other conditions such as the temperature difference shall conform to the cooling method. This step may be carried out using a known machine such as a cocoon boiling machine.

[0093] The method and conditions to be used can be appropriately selected in consideration of the purpose, the properties of the silk threads constituting the cocoons, or the equipment, etc. For example, when the purpose is not to perform heat treatment, the low-temperature decompression method or the low-temperature cooling method can be used, and when the purpose is to shorten the cocoon boiling time, the high-temperature decompression method, the cocoon boiling cooling method, or the steaming method can be used.

[0094] This step can be carried out multiple times. In that case, it may be carried out under the same method and conditions, or the method and conditions used each time may be changed.

[0095] The method and conditions used in the method of the present invention may be determined in relation to, for example, the reeling efficiency (the ratio of cocoons that can be reeled), the unraveling rate (the number of cocoons per cut), or the water absorption amount, etc. For example, it may be determined so that the reeling efficiency is 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 85% or more, 90% or more, 95% or more, or 100%. Also, for example, it may be determined so that the unraveling rate is 80% or more.

[0096] The water absorption amount per cocoon varies depending on the cocoons used, but usually, it may be 1 g or more, 1.1 g or more, 1.2 g or more, 1.3 g or more, or 1.4 g or more, or compared with the case where the same penetration process is carried out on cocoons not treated with an organic solvent, etc., for example, it may be 1.05 times or more, 1.06 times or more, 1.075 times or more, 1.1 times or more, 1.15 times or more, 1.2 times or more, 1.3 times or more, 1.4 times or more, 1.5 times or more, or 1.6 times or more.

[0097] 1-4. Effects By the method of this embodiment, cocoons for reeling can be prepared at low temperatures or in a short time. These cocoons for reeling can be directly reeled after finding the end of the cocoon filament. In addition, cocoons for reeling that retain the activity of functional regions that are easily heat-denatured and / or easily denatured under basic conditions can be obtained. Furthermore, according to the method of this embodiment, the normal cocoon cooking equipment can be used as it is to cook the cocoons in a shorter time. Therefore, the method of the present invention can be used for various purposes, for example, to reduce the load on silk yarn, to shorten the time, or to reduce the silk reeling cost, etc.

[0098] Also, by the method of this embodiment, cocoons that can be directly reeled after finding the end of the cocoon filament can be obtained. For example, cocoons prepared without performing the penetration step of this method can be stored or provided as cocoons for pre-penetration before reeling. In this case, by performing the penetration step on the stored or provided cocoons for pre-penetration before reeling, cocoons for reeling can be prepared and used for reeling.

[0099] 2. Method for manufacturing raw silk 2-1. Overview The second embodiment of the present invention is a method for manufacturing raw silk. The method of this embodiment includes a cocoon end-finding step and a reeling step as essential steps. According to the method of this embodiment, raw silk can be manufactured from the cocoons for reeling prepared in the first embodiment.

[0100] 2-2. Configuration The method of this embodiment includes a cocoon end-finding step and a reeling step as essential steps.

[0101] 2-2-1. Cocoon end-finding step The "cocoon end-finding step" is an essential step and is a step of finding the end of the cocoon filament in the cocoons for reeling obtained in the first embodiment.

[0102] Since the cocoons for reeling have been described in detail in the first embodiment, the description here is omitted. The methods and conditions used in this process are not particularly limited. For example, the methods commonly used for reeling silk cocoons can be used. For example, it may be carried out by rubbing the surface of the cocoon in the water in which the cocoon is soaked during reeling (hereinafter often referred to as "reeling water" in this specification) with a reeling broom or the like. Unless a large amount of water in the cocoon cavity is lost, it is not necessarily required to carry out this process with the reeling cocoon immersed in water. Also, the method of rubbing the cocoon surface is not particularly limited as long as the silk end can be drawn out.

[0103] The temperature and composition of the reeling water are not particularly limited. For example, the reeling water commonly used for normal reeling of silkworm cocoons may be used, or those exemplified in the section on penetration in the first aspect may be used. For example, when this method is carried out continuously with the method described in the first aspect, the water used for penetration may be used directly as the reeling water, or the water used in this process may be exchanged or its composition changed after this process and then used in the reeling process.

[0104] 2-2-2. Reeling process The "reeling process" is an essential process and is a process of reeling based on the silk end obtained in the reeling process. This process can be carried out simultaneously with or after the reeling process.

[0105] Among the silk ends drawn out in the reeling process, any silk end can be selected for reeling. For example, similar to the selection of silk in the normal silk reeling method of silkworm cocoons, it may be carried out by continuing the operation of further drawing out the silk end until one silk end remains.

[0106] The method used in this process is not particularly limited. For example, the methods commonly used for reeling silkworm cocoons can be used. Also, since the main purpose of this process is to produce raw silk from cocoons, any method that can draw silk from cocoons can be used in this process.

[0107] This process may be carried out manually by hand-reeling or sitting-reeling, or the fineness may be controlled by constant-strand reeling using a sitting-reeling machine or a multi-strand reeling machine, or constant-denier reeling using an automatic reeling machine.

[0108] As necessary, it is possible to address defects in the yarn such as knotting, or to perform fineness control such as doubling and / or twisting. These methods are known in the art and are not particularly limited.

[0109] This method may be carried out as a series of steps using an automatic reeling machine capable of continuously performing skein winding and reeling.

[0110] 2-3. Uses of Raw Silk Any product can be manufactured from the raw silk obtained by the method of this embodiment and / or the degummed silk obtained by degumming the raw silk. Specifically, for example, non-woven fabrics, fillers, surgical sutures, woven fabrics, knitted fabrics, strings for musical instruments, etc. can be mentioned.

[0111] At that time, it may contain any other fiber material, etc. Although not particularly limited, specifically, for example, natural fibers including other animal fibers such as wool and plant fibers such as cotton, semi-synthetic fibers such as acetate, regenerated fibers such as rayon, synthetic fibers such as polyester, or inorganic fibers such as glass fibers can be mentioned.

[0112] The use of the product is not particularly limited. For example, when the reeling cocoons used in the method of this embodiment are prepared at a low temperature, even if the silk yarn contains a functional region where thermal denaturation is likely to occur, raw silk retaining its activity can be obtained by the method of this embodiment. In that case, it may be used for applications where the functional region can exhibit its function.

[0113] By performing the method of the first embodiment at a low temperature and degumming it by a degumming method that can be carried out at a low temperature after the method of this embodiment, even when the silk yarn contains a functional region where thermal denaturation is likely to occur, a degummed silk containing a functional region that can function can be obtained. As the degumming method used in this case, any known method can be used.

Examples

[0114] <Example 1. Improvement of Skein Winding Efficiency by Organic Solvent Treatment> (Purpose) Examine the effect of treatment with organic solvents on the efficiency of reeling cocoons.

[0115] (Method) As samples, dry cocoons of Bombyx mori of Gunma 200 were used. The organic solvent treatment was carried out by immersing the cocoons in an organic solvent of the following composition for 30 seconds.

[0116] As the organic solvent, aqueous ethanol solutions with ethanol concentrations of 20, 40, 60, 80, and 99.5 vol% were used. As a control, water without ethanol (0 vol% aqueous ethanol solution) was used.

[0117] After the organic solvent treatment, the cocoons were immersed in normal temperature water and left standing for 8 minutes under reduced pressure (gauge pressure: -600 mmHg) to allow water to penetrate into the cocoon cavity. After restoring the pressure to atmospheric pressure over 2 minutes, the surface of the cocoon was rubbed with a reeling brush to draw out the thread end.

[0118] The reeling efficiency was calculated as the ratio of the number of cocoons from which the correct thread end could be drawn out among the cocoons (10 each) used for each condition.

[0119] (Results) The results are shown in Table 1.

[0120]

Table 1

[0121] Table 1 shows the reeling efficiency when each organic solvent was used. The reeling efficiency increased depending on the ethanol concentration. The reeling efficiency was 20% for the 0 vol% control, while it was 60% for the 40 vol% aqueous ethanol solution, 80% for the 60 vol% aqueous ethanol solution, 100% for the 80 vol% aqueous ethanol solution, and 100% for the 99.5 vol% aqueous ethanol solution, showing excellent reeling efficiency.

[0122] When observing the cocoons, in the control group, translucent (where water had penetrated) and non-translucent (white) parts were randomly present in the cocoon layer. On the other hand, in the cocoons treated with organic solvent, it was found that the cocoon layer was translucent throughout and water had penetrated uniformly.

[0123] Furthermore, when reeling silk from the thread ends drawn out by reeling, it was possible to reel more than 450 m of silk thread from any of the reeled cocoons. According to the selection criteria for the water-reeling strain (Dainippon Silk Association Silk Bulletin No. 41 p. 2-3 (2011)), all of them were judged to be reelable.

[0124] Also, the physical properties of raw silk reeled from fresh cocoons of the day-neutral four-way crossbreed Ariake by the same treatment as above were compared with those of raw silk obtained by normal cocoon cooking of dry cocoons of the same variety. As a result, regarding strength, the former was 4.25 ± 0.10 g / d and the latter was 4.29 ± 0.05 g / d, etc., and no significant difference was found in the physical properties of the two.

[0125] From the above, it was found that by organic solvent treatment, it is possible to prepare cocoons that can be reeled and reeled without heating, without affecting the physical properties of raw silk.

[0126] <Example 2. Relationship between water penetration into the cocoon layer and concentration of organic solvent> (Purpose) Examine the effect of organic solvent treatment on water penetration into the cocoon layer and the relationship between the concentration of organic solvent and penetration.

[0127] (Method) Samples and organic solvent treatment were basically carried out in the same manner as in Example 1. The water absorption was calculated for each cocoon by subtracting the weight of the cocoon before organic solvent treatment from the weight of the cocoon after removing the water in the cocoon cavity after recompression. Here, the removal of water in the cocoon cavity was carried out by lifting the cocoon after recompression out of the water and decompressing it again. Experiments were conducted using 10 cocoons under each concentration condition.

[0128] (Result) The results are shown in Fig. 1. Fig. 1 is a graph showing the water absorption of cocoons (cocoon layers) when organic solvent treatment is carried out using ethanol aqueous solutions of different concentrations. The water absorption of the cocoon layer showed a change depending on the ethanol concentration. Compared with the control of 0% by volume, the water absorption increased significantly when a 60% by volume ethanol aqueous solution was used. Furthermore, the water absorption increased further at concentrations of 80% by volume or more, and there was no significant difference in the water absorption between 80% by volume and 99.5% by volume.

[0129] From the above, it was found that the water absorption of the cocoon layer increases by organic solvent treatment and that the increase is concentration-dependent.

[0130] <Example 3. Relationship between water penetration into the cocoon layer and the type of organic solvent, etc.> (Objective) By changing the type of organic solvent, etc. used, the water absorption of the cocoon layer is measured, and the relationship between the type of organic solvent, etc. and penetration is investigated.

[0131] (Method) The treatment with the sample and the organic solvent was basically carried out in the same manner as in Example 2. As the organic solvent, ethanol aqueous solutions of 99.5 - 99.8% by volume, methanol aqueous solutions, and 2-propanol aqueous solutions were used. The experiment was carried out using 10 cocoons under each condition.

[0132] (Result) The results are shown in Fig. 2. Fig. 2 is a graph showing the water absorption of the cocoon layer when organic solvent treatment is carried out using different organic solvents. Good water absorption of 1.4 g / cocoon or more was observed in all cases of using any organic solvent. Also, there was no significant difference in the water absorption depending on the type of solvent.

[0133] In addition, for organic solvents (ethyl acetate, acetone, N,N-dimethylformamide, and acetonitrile) and organic acids (acetic acid and propionic acid), good penetration into the cocoon layer and substitution with water were confirmed in a simple penetration test into the cocoon layer using cocoon pieces.

[0134] Even when chloroform and isopentyl alcohol were used as organic solvents, good penetration of the organic solvents into the cocoon layer was observed, but substitution with water was difficult, and it was necessary to remove them by washing with a water-soluble organic solvent (ethanol) or the like.

[0135] From this, it was found that any organic solvent can promote the penetration of water into the cocoon layer regardless of its type.

[0136] <Example 4. Influence of Exposure to Organic Solvents on Functional Regions in Silk Fibers> (Objective) By exposing cocoons containing functional regions to organic solvents, the influence of the organic solvents on the functional regions was investigated.

[0137] (Method) As samples, dry cocoons obtained from silkworms that spin silk containing green fluorescent protein as a functional region in the fibroin H chain were used. As a control, dry cocoons of a common variety (variety: N137 × 146 denier) that do not contain functional regions were used.

[0138] As the green fluorescent protein, silkworms (background strain GFP: Gunma × 200; Azami Green: N604 × C511) that express fibroin fused with GFP or Azami Green were used.

[0139] An 80% (v / v) ethanol aqueous solution was used as the organic solvent. Exposure to the organic solvent was carried out by immersing the cocoons in an 80% (v / v) ethanol aqueous solution for 30 seconds and then lifting them out and allowing the cocoons to stand for 1 day to dry naturally. Thereby, the cocoons were exposed to ethanol until the ethanol was completely evaporated from the cocoon layer and the cocoon cavity.

[0140] Also, in some cocoons containing safflower green as a functional region, normal cocoon cooking was performed without organic solvent treatment. As the cocoon cooking treatment, cocoon cooking was carried out by a conventional method using a VP type vacuum cocoon cooking machine (Harada Co., Ltd.).

[0141] The control cocoons, the cocoons without the above exposure treatment, and the treated cocoons were observed under bright field. Also, using a blue LED as the excitation light, the fluorescence of the cocoons was observed in the dark.

[0142] (Results) The results are shown in FIGS. 3 and 4. FIG. 3 is a diagram showing the state of cocoons when cocoons containing safflower green as a functional region are subjected to organic solvent treatment. Regardless of the presence or absence of the exposure treatment to ethanol, the intensity of the observed fluorescence did not change.

[0143] On the other hand, as shown in FIG. 4, compared with the case where no cocoon cooking treatment was performed (the left column in FIG. 4), the fluorescence of safflower green was lost when normal cocoon cooking treatment was performed (the right column in FIG. 4).

[0144] Similarly, when cocoons containing GFP as a functional region were used, no influence by the organic solvent was observed.

[0145] From the above, it was found that even when using cocoons containing a functional region whose activity can be lost by normal cocoon cooking, cocoons that can be reeled without impairing the activity can be prepared.

[0146] <Example 5. Influence on the functional region by organic acid treatment and improvement of reeling efficiency> (Objective) Examine the influence of treatment with organic acid on the functional region in silk thread and the influence on the reeling efficiency of cocoons.

[0147] (Method) As samples, dry cocoons obtained from silkworms that spin silk threads containing azami green as a functional region in the fibroin H chain, and dry cocoons of a common variety (variety: Gunma 200) that do not contain a functional region were used.

[0148] A 99.7% by volume aqueous acetic acid solution was used as the organic acid. In the cocoons containing azami green, treatment was carried out in the same manner as in Example 4 except that a 99.7% by volume aqueous acetic acid solution was used as the organic solvent, and the effect of acetic acid treatment on the cocoons was examined.

[0149] In the cocoons of the common variety (10 pieces), treatment was carried out in the same manner as in Example 1 except that a 99.7% by volume aqueous acetic acid solution was used as the organic solvent, and the reeling efficiency was measured.

[0150] (Results) The results are shown in Fig. 5. Fig. 5 is a diagram showing the state of cocoons when cocoons containing azami green as a functional region are subjected to organic acid treatment using acetic acid. Regardless of the presence or absence of exposure treatment to acetic acid, the observed fluorescence intensity did not change.

[0151] Also, even when organic acid treatment was carried out using acetic acid, an excellent reeling efficiency of 80% was shown.

[0152] From the above, it was found that even when an organic acid such as acetic acid is used as the organic solvent, cocoons that can be reeled without impairing the activity of the functional region can be prepared.

[0153] <Example 6. Shortening of the cocoon boiling time using organic solvent treatment> (Purpose) Examine the effects of organic solvent treatment on the cocoon boiling time, reeling efficiency, and physical properties of the raw silk produced when the cocoon boiling cooling method is carried out after organic solvent treatment.

[0154] (Method) As samples, dry cocoons of Nisshin 137 × Shishin 146 were used. The organic solvent treatment was carried out by immersing the cocoons in an 80% by volume aqueous ethanol solution as the organic solvent for 30 seconds.

[0155] After immersing the cocoons subjected to the organic solvent treatment in hot water heated to 95°C for about 90 seconds, they were transferred to warm water at 60°C and immersed for about 60 seconds to perform the cocoon boiling and cooling method.

[0156] As a control group, cocoons that were not subjected to the organic solvent treatment and were boiled by the conventional method using a VP-type vacuum cocoon boiling machine (Harada Co., Ltd.) were used.

[0157] For the cocoons boiled under each condition, reeling was performed using a reeling broom. The reeling rate was calculated by a reeling test according to the old cocoon inspection method (Cocoon Inspection Office Operation Council, 1984). The physical properties of the raw silk obtained by reeling were measured.

[0158] (Results) The results are shown in Table 2.

[0159]

Table 2

[0160] Table 2 shows the reeling efficiency from cocoons subjected to shortened cocoon boiling using the organic solvent treatment and normal cocoon boiling, and the physical properties of the raw silk produced (reeled) by reeling. In the group using the organic solvent treatment, although the cocoon boiling time was significantly shorter (about 3 minutes compared to about 15 minutes usually), there was no significant difference in the reeling efficiency such as the reeling rate and the length of cocoon filaments compared to normal cocoon boiling. Also, there was no difference in the physical properties such as the strength and elongation of the reeled raw silk depending on the cocoon boiling method.

[0161] From this, it was found that by the organic solvent treatment, it is possible to perform cocoon boiling in a significantly shorter time without impairing the reeling efficiency and the physical properties of the raw silk.

Claims

1. A method for preparing cocoons for reeling, comprising: a contacting step of contacting cocoons with an organic solvent and / or an organic acid having a concentration of 45% by volume or more, and an infiltration step of infiltrating water or an aqueous solution into the contacted cocoon layer and the cocoon cavity after the contacting step and, the temperature of the organic solvent and / or the organic acid is 65°C or lower, the temperature of the water or the aqueous solution is 65°C or lower, not including high-temperature heat treatment at 80°C or higher, said preparation method.

2. The preparation method according to claim 1, further comprising a removing step of removing the organic solvent and / or the organic acid before the infiltration step.

3. The preparation method according to claim 1 or 2, wherein the infiltration step is performed by an immersion method.

4. The preparation method according to claim 1 or 2, wherein the infiltration step includes a step of reducing the pressure inside the cocoon cavity to reduce the pressure inside the cocoon cavity.

5. The preparation method according to claim 4, wherein the infiltration step is performed by a low-temperature decompression method and / or a low-temperature cooling method.

6. The organic solvent includes one or more organic solvents selected from the group consisting of lower alcohols, acetone, N,N-dimethylformamide, acetonitrile, and ethyl acetate. The preparation method according to any one of claims 1 to 5.

7. The organic acid includes acetic acid and / or propionic acid. The preparation method according to any one of claims 1 to 6.

8. Cocoons for reeling prepared by the preparation method according to any one of claims 1 to 7.

9. A method for producing raw silk, comprising: a reeling-off step of performing reeling-off on the cocoons for reeling obtained by the preparation method according to any one of claims 1 to 7, and a reeling step of performing reeling based on the thread end obtained in the reeling-off step including said production method.

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