Silkworm feed and method for producing silk thread

Abstract

The present disclosure provides a silkworm feed containing carbon black.

Description

Silkworm feed and silk production method

[0001] This disclosure relates to silkworm feed and a method for producing silk.

[0002] Natural materials are used in a wide range of industrial fields, including the textile industry and the medical field, due to their excellent physical properties and environmental compatibility. In particular, silk thread produced by silkworms (Bombyx mori) is one of the natural protein-derived materials, and its industrial value is highly recognized because it combines excellent mechanical properties with the potential for mass production.

[0003] Conventionally, various studies have been conducted to improve the functionality of silk threads. For example, methods such as feeding silkworms with feed supplemented with carbon nanotubes or graphene (Non-Patent Document 1) and methods for creating silkworms capable of producing high-strength silk threads through crossbreeding or genetic modification technology (Non-Patent Documents 2-3) have been reported.

[0004] However, the method described in Non-Patent Document 1 makes mass production of silk difficult due to the high production costs of carbon nanotubes and graphene. Furthermore, there are concerns about the toxicity of these substances, and their effects on silkworm cocooning rates and the fineness and whiteness of raw silk have not yet been clarified.

[0005] On the other hand, the methods described in Non-Patent Document 2 or Non-Patent Document 3 require the application of genetic modification technology to obtain raw silk with the desired fineness, whiteness, and high strength, which presents the problem of requiring considerable effort and expense.

[0006] Nano Lett. 2016, 16, 6695.J.Silk Sci. Tech. Jpn 29, 51-57(2021)Biological sample analysis Vol.37, No3 (2014)

[0007] This disclosure is made to solve the above-mentioned problems and aims to provide silkworm feed and a method for producing silk thread.

[0008] One aspect of the present disclosure is a silkworm feed containing carbon black. Another aspect of the present disclosure is a method for producing silk, comprising feeding a substance containing carbon black to silkworms.

[0009] According to this disclosure, a silkworm feed and a method for producing silk thread can be provided.

[0010] Figure 1 shows the cocooning rate of silkworms fed a diet containing 1% by mass of Ketjenblack and a control group fed a diet without carbon material.

[0011] The following describes non-limiting embodiments of this disclosure. This disclosure is not limited to the embodiments described below.

[0012] <Silkworm Feed> In one embodiment of the present disclosure, a silkworm feed containing carbon black may be provided. By feeding silkworms the silkworm feed of the embodiment, the cocooning rate of the silkworms can be increased, and silk threads with low fineness and high strength can be obtained. Furthermore, by feeding silkworms the silkworm feed of the embodiment, cocoon threads and raw silk with high whiteness can be obtained.

[0013] In this disclosure, "silkworm" refers to the larva of the silkworm moth (Bombyx mori). The silkworm may be wild-type, mutant, or genetically modified. Furthermore, the silkworms in this disclosure include individuals of various strains widely used for sericulture both in Japan and abroad, such as Gunma 200.

[0014] In this disclosure, “carbon black” means, as understood by those skilled in the art, a carbon material containing fine carbon particles, or a carbon material having a similar structure, produced by incomplete combustion or thermal decomposition of carbon-containing raw materials (e.g., petroleum products or natural gas). These carbon particles typically have a particle size of 10 nm to 500 nm and mainly have an amorphous structure and a partially graphite-like structure, and 10 nm 2 / g~1500m 2It is understood by those skilled in the art that carbon black has a specific surface area of ​​1 / g. The particle size of carbon black can be evaluated using transmission electron microscopy (TEM) images. Specifically, for each primary particle observed on the TEM, the size of each primary particle is determined by a predetermined measurement method such as the ferret diameter or projected area diameter. Then, the measurement results of 100 or more randomly selected primary particles are statistically processed, and the representative value (e.g., arithmetic mean) can be used as the particle size of carbon black. Here, primary particles refer to basic particles that can be independently identified in TEM observation, and are distinguished from aggregates formed by the fusion of multiple primary particles or agglomerates formed by these particles bound together by weak bonds. The surface area of ​​carbon black can be measured by methods known to those skilled in the art, such as adsorption methods including nitrogen adsorption.

[0015] The silkworm feed in this embodiment may be mulberry leaves or artificial feed for silkworms. Preferably, the mulberry leaves are those that have been cultivated, harvested, washed, dried, and preserved in a manner known to those skilled in the art to be suitable for silkworm rearing. The artificial feed may be a feed containing one or more of the following: mulberry leaf powder, soybean powder, rice bran, starch, cellulose, vitamins, or minerals. As the silkworm feed in this embodiment, commercially available hot water-based feed or artificial feed such as paste feed like Kuwanohana (registered trademark) can be used. The artificial feed may be adjusted to a nutritional composition appropriate to the growth stage of the silkworms. The artificial feed may contain additives such as antioxidants, preservatives, and antibacterial agents.

[0016] The silkworm feed of the embodiment contains carbon black. When the silkworm feed of the embodiment uses mulberry leaves as a base material, carbon black can be added, for example, by spraying it onto the mulberry leaves as an aqueous dispersion. When artificial feed is used as a base material, the silkworm feed of the embodiment can be produced by mixing carbon black with a base feed such as a commercially available artificial feed. In this case, a dispersant or surfactant may be added as appropriate to suppress the aggregation of carbon black and obtain a more homogeneous dispersion.

[0017] In the silkworm feed of the embodiment, carbon black may be present in an amount of 0.001% to 10% by mass, 0.01% to 5% by mass, or 0.1% to 2% by mass relative to the total mass of the silkworm feed. In the silkworm feed of the embodiment, it is preferable that carbon black be present in an amount of 0.5% to 1.5% by mass relative to the total mass of the silkworm feed.

[0018] In the silkworm feed of the embodiment, carbon black may include conductive carbon black. In this disclosure, "conductive carbon black" refers to an insulating substrate such as resin (e.g., 1.0 × 10 8 Ω・cm or more, 1.0×10 9 Ω・cm or more, 1.0×10 10 Ω·cm or greater, or 1.0 × 10⁻⁶ 11 A carbon black that imparts conductivity to a substrate (with a conductivity of Ω·cm or more), and the internal resistivity of one or more types of insulating substrates to which it is added is 1.0 × 10 5 This refers to carbon black capable of having a resistivity of Ω·cm or less. Conductive carbon black preferably has an internal resistivity of 1.0 × 10⁻⁶ of the insulating substrate. 3 This is a carbon black with a conductivity of Ω·cm or less, more preferably 1.0Ω·cm or less. Conductive carbon black is widely used in the chemical industry and is readily available at low cost. By using conductive carbon black, it is possible to produce silk yarn with excellent properties without using expensive carbon materials such as carbon nanotubes or graphene.

[0019] The conductive carbon black in the embodiment is not particularly limited, and various commercially available conductive carbon blacks can be appropriately selected and used. Examples of conductive carbon blacks include Ketjenblack®, Vulcan®, Acetylene Black, and Black Pearls®. Among these, examples of Ketjenblack include Ketjenblack EC300J, Carbon ECP, Ketjenblack EC600JD, Carbon ECP600JD, and Lionite® CB. Examples of Vulcan include Vulcan XC-72, Vulcan XC-72R, Vulcan P, and Vulcan XC. Examples of acetylene black include Denka Black (registered trademark) Li-100, Denka Black Li-250, Denka Black Li-400, Denka Black Li-435, Acetylene Black 50%-03, Acetylene Black 75%-03, Acetylene Black 100%-03, Acetylene Black Granular-03, and HS-100. Examples of Black Pearls include Black Pearls 880, Black Pearls 1300, and Black Pearls 2000. In the silkworm feed of the embodiment, carbon black may include one or more selected from the group consisting of Ketjenblack, Vulcan, acetylene black, and Black Pearls.

[0020] The silkworm feed according to the embodiment may be substantially free from carbon nanotubes and graphene. In the present disclosure, the phrase "substantially free from carbon nanotubes and graphene" means that the silkworm feed contains no carbon nanotubes or graphene at all, or even if either of them is contained therein, it is contained only in an amount that does not significantly affect the strength, fineness and whiteness of silk produced by silkworms that ingest the silkworm feed. The properties of such silk can be evaluated by methods known to those skilled in the art. In the silkworm feed according to the embodiment, "substantially free from carbon nanotubes and graphene" may mean that the content of carbon nanotubes, graphene, or the total content thereof is 0.0001% by mass or less, 0.00001% by mass or less, or 0.000001% by mass or less based on the total mass of the feed.

[0021] The silkworm feed according to the embodiment may be substantially free from carbon nanotubes, graphene and graphite. As understood by those skilled in the art, "graphite" in this embodiment refers to sp 2This refers to a crystalline substance having a layered structure composed of bonded carbon atoms. Note that the graphite-like structure contained in carbon black is not included in "graphite" in this embodiment due to its low and incomplete crystallinity. "Containing substantially no carbon nanotubes, graphene, and graphite" means that the silkworm feed contains no carbon nanotubes, graphene, or graphite at all, or, if any of these are present, only in amounts that do not significantly affect the strength, fineness, and whiteness of the silk produced by silkworms consuming the feed. The properties of these silks can be evaluated by methods known to those skilled in the art. In the silkworm feed of this embodiment, "containing substantially no carbon nanotubes, graphene, and graphite" may mean that the content of carbon nanotubes, graphene, graphite, or the sum thereof is 0.0001% by mass or less, 0.00001% by mass or less, or 0.000001% by mass or less relative to the total mass of the feed.

[0022] <Method for Manufacturing Silk Yarn> In one embodiment of the present disclosure, a method for manufacturing silk yarn may be provided, which includes feeding a substance containing carbon black to silkworms. The elements of this embodiment (carbon black, silkworms, silkworm feed, etc.) may be described in the <Silkworm Feed> section.

[0023] In this disclosure, "silk yarn" includes yarn based on fibroin fibers obtained from cocoons formed by silkworms, and includes raw silk obtained through general silk production processes (such as boiling cocoons and reeling), as well as yarn obtained by processing such as scouring, dyeing, and twisting. The silk yarn (cocoon yarn) itself extruded by silkworms is also included in "silk yarn" in this disclosure. Furthermore, these silk yarns that have undergone weaving processes and are incorporated into fabrics, for example as warp and / or weft yarns, are also included in "silk yarn" in this disclosure. In this disclosure, any silk yarn produced from cocoons or yarn extruded by silkworms is treated as "silk yarn" regardless of its form, the details of the manufacturing process, and its final use. The silk yarn manufacturing method of the embodiment may be a raw silk manufacturing method.

[0024] The silk production method of the embodiment includes feeding silkworms a substance containing carbon black. The substance containing carbon black in the embodiment may be a substrate in which carbon black is dispersed. Examples of substrates include mulberry leaves, artificial feed, solids such as soy flour, rice bran, and cellulose powder that are raw materials for artificial feed, or aqueous media containing a thickener or gelling agent (e.g., agarose gel). In the silk production method of the embodiment, the substance containing carbon black may include silkworm feed containing carbon black.

[0025] To improve the palatability of a substance to silkworms, an extract of mulberry leaves can be added to a substance containing carbon black. Mulberry leaf extract is obtained by extracting mulberry leaves with a solvent such as ethanol, and it is known to those skilled in the art that it contains components that promote silkworm feeding. Furthermore, the physical properties of the substance containing carbon black can be adjusted to suit the feeding characteristics of silkworms. For example, by adding an appropriate amount of a gelling agent such as gelatin, agar, or carboxymethylcellulose, it is possible to adjust the texture to one that silkworms prefer.

[0026] Substances containing carbon black can be prepared in various physical forms, such as solid, gel, or paste. When using mulberry leaves, carbon black powder can be dispersed in water and sprayed onto the leaves as a dispersion. In the case of gel or paste-like substances, a method of mixing the carbon black dispersion with a gel or paste-like substrate or a method of solidifying the carbon black dispersion with a gelling agent can be employed. In this case, a dispersant or surfactant may be added as appropriate to suppress the aggregation of carbon black and obtain a more homogeneous dispersion.

[0027] The method for producing silk thread according to the embodiment may include producing silk thread using silkworms fed with carbon black. The method for producing silk thread according to the embodiment may include causing silkworms to spin cocoons to produce cocoons, and producing silk thread using the cocoons. Cocoons can be obtained by having silkworms ingest feed supplemented with a substance containing carbon black and causing the silkworms to spin cocoons. The obtained cocoons can be subjected to a drying step and a cocoon cooking step according to conventional methods, and then taken out as raw silk through a reeling step. In these production steps, methods widely known to those skilled in the art for ordinary raw silk production can be applied.

[0028] Furthermore, the obtained raw silk can be subjected to processing steps such as a washing step, a degreasing step, a dyeing step, and a twisting step as post-processes if necessary. It can also be formed into a woven fabric through a weaving step. Conventional methods well known to those skilled in the art can also be applied to these post-processes. Processing conditions in each step can be appropriately set by those skilled in the art according to the use of the obtained silk thread or the required properties.

[0029] In the method for producing silk thread according to the embodiment, the carbon black may include conductive carbon black. Furthermore, in the method for producing silk thread according to the embodiment, the carbon black may include one or more selected from the group consisting of Ketjenblack, Vulcan, acetylene black, and Black Pearls. The description in the <Silkworm Feed> section can be applied to these carbon blacks.

[0030] In the method for producing silk thread according to the embodiment, the substance containing carbon black may be a substance containing carbon black that does not contain a substantial amount of carbon nanotubes and graphene. Here, the description in the <Silkworm Feed> section can be applied to the statement "does not contain a substantial amount of carbon nanotubes and graphene".

[0031] In one embodiment of the present disclosure, a method for producing silk yarn with increased whiteness may be provided, comprising feeding silkworms a substance containing carbon black. Here, "increased whiteness" may mean that the whiteness is greater than that of silk yarn produced from control silkworms that are not fed a substance containing carbon black.

[0032] One embodiment of the present disclosure is a method for producing silk yarn with increased strength, comprising feeding a substance containing carbon black to silkworms. Herein, "increased strength" may mean that the strength is greater than that of silk yarn produced from control silkworms that are not fed a substance containing carbon black.

[0033] Examples of the present disclosure are described below, but the present disclosure is not limited to the examples described below. Also, although the following examples are based on typical drying and reeling conditions, this does not mean that the present disclosure is limited to specific drying and reeling conditions.

[0034] Silkworms were fed a diet containing Ketjenblack EC600JD (manufactured by Lion Specialty Chemicals, Inc.; hereinafter simply referred to as "Ketjenblack" in this example), a conductive carbon black, and the properties of the resulting cocoon silk and reeled raw silk were evaluated. After pupation, the cocoons were dried in stages from 115°C to 60°C, and the reeling conditions were set to a boiling temperature of 40-90°C and a reeling speed of approximately 52 m / min.

[0035] For the measurement of fineness, a fineness yarn (raw silk measured to 500 cm) was first prepared. The prepared fineness yarn was left to stand for more than 24 hours in an environment of 20°C and 65% humidity, and then weighed using an electronic balance to determine the fineness (d: denier). The fineness value was calculated from the average value obtained from 10 measurements.

[0036] Strength was measured using a Tensilon universal material tester RTF-1250 manufactured by A&D Co., Ltd., installed in an environment of 20°C and 65% humidity. The gripping distance used for measurement was 200 mm, and the stretching speed was 200 mm / min. The test was performed 20 times, and the strength value was calculated from the average value obtained from these measurements.

[0037] In this embodiment, "elongation" means elongation at break (gf / d) unless otherwise specified.

[0038] The whiteness of the cocoons and raw silk was measured using a Konica Minolta CM-3700A, light source: D 65 The following was used. The whiteness of the cocoons was measured three times each, and the whiteness of the raw silk was calculated from the average value obtained from five measurements of raw silk wrapped around a white cardboard board.

[0039] In the experiment, silkworms were divided into two groups. One group was fed a commercially available feed (mulberry leaf feed) supplemented with 1% by mass of Ketjenblack, while the other control group was fed only feed that did not contain carbon material. When the cocooning rate was measured for each group, the cocooning rate of the silkworms fed the feed containing Ketjenblack was significantly higher than that of the control group (Figure 1).

[0040] Next, the properties of the reeled raw silk were evaluated. Statistical analysis was performed using the t-test to assess significant differences compared to the control group.

[0041] Measurements of the fineness of raw silk reeled from 10 cocoons revealed that silkworms fed with feed containing Ketcheblack produced finer (thinner) threads (Table 1). While not intended to limit the mechanism of the effect, it is presumed that the production of finer (thinner) threads is due to the thinning of the silk glands in silkworms that consumed feed containing a large amount of Ketcheblack.

[0042] Furthermore, when the physical properties (strength) of the raw silk were measured, the raw silk from silkworms fed with feed containing Ketcheblack showed higher strength than that of the control group (Table 2). Although this is not intended to limit the mechanism by which the effect is obtained, it is presumed that the reason why the raw silk obtained from silkworms fed with feed containing Ketcheblack showed higher strength than that of the control group is that the addition of Ketcheblack changed the crystallinity and / or amino acid composition of the proteins constituting the raw silk, thereby improving its physical strength.

[0043] Regarding the visual characteristics of cocoons and reeled raw silk, colorimetric tests were conducted using the computer color matching method, L * a * b * Brightness (L) * (value) and color value (a * value, b * The value was evaluated. In addition, the whiteness (W value) was also evaluated based on these results. * The higher the value, the brighter it becomes. * The value indicates that the color becomes more reddish as the positive value increases, and the color becomes more greenish as the negative value increases. Also, b * It is known that a larger positive value results in a more yellowish tint, while a larger negative value results in a more bluish tint.

[0044] The brightness (L) of cocoons and raw silk produced by silkworms that have ingested feed containing Ketjenblack. * (value), color value (a * value, b * When comparing the color values ​​(W value) and whiteness (W value) with the control group, a statistically significant difference was observed. Furthermore, when cocoons extruded by silkworms that ingested feed containing Ketjenblack were evaluated, it was confirmed that the brightness was slightly reduced, redness and yellowness were suppressed, and as a result, the whiteness was significantly improved compared to the control group. Similar results were obtained for raw silk (Tables 3 and 4). To evaluate the color difference between cocoons and reeled raw silk, CIE 1976 (L * a * b * Based on the color space, the color difference (ΔE) from the control area. * The color difference ΔE was calculated. *This was calculated using the following formula. Here, ΔL * is brightness (L * The difference between the values, Δa * is the color value a * The difference between, Δb * This is the color value b * This represents the difference. ΔE * A larger value indicates a greater color difference from the control group. The color difference (ΔE) between the cocoon and raw silk calculated from this formula is shown. * The whiteness values ​​were 3.69 for cocoons and 0.87 for raw silk, showing a significant color difference for cocoons. Although not intended to limit the mechanism by which the effect is obtained, the observed improvement in whiteness is presumed to be due to a change in the content of sericin and fibroin that make up the cocoon threads.

[0045] These results clearly show that silkworms fed a diet containing carbon black exhibit beneficial effects in various aspects, including improved cocoon production rates, reduced silk fiber fineness, increased physical strength, and improved whiteness of both cocoon and raw silk. The above results illustrate that the addition of carbon black to silkworm feed contributes to improving silk quality.

[0046] This disclosure includes the following embodiments: (1) A silkworm feed containing carbon black. (2) The silkworm feed according to claim 1, wherein the carbon black contains conductive carbon black. (3) The silkworm feed according to claim 1 or 2, wherein the carbon black contains one or more selected from the group consisting of Ketjenblack, Vulcan, acetylene black, and Black Pearls. (4) The silkworm feed according to any one of claims 1 to 3, which does not contain carbon nanotubes and graphene in substantial amounts. (5) A method for producing silk, comprising feeding a substance containing carbon black to silkworms. (6) The method for producing silk according to claim 5, wherein the substance containing carbon black contains a silkworm feed containing carbon black. (7) The method for producing silk according to claim 5 or 6, wherein the carbon black contains conductive carbon black. (8) The method for producing silk according to any one of claims 5 to 7, wherein the carbon black contains one or more selected from the group consisting of Ketjenblack, Vulcan, acetylene black, and Black Pearls. (Clause 9) A method for producing silk yarn according to any one of Clauses 5 to 8, wherein the substance containing carbon black does not contain carbon nanotubes and graphene in substantial amounts. (Clause 10) A method for producing a woven fabric, comprising weaving using silk yarn produced by the method for producing silk yarn according to any one of Clauses 5 to 9 as warp and / or weft. (Clause 11) A method for producing silk yarn with increased whiteness, comprising feeding a substance containing carbon black to silkworms. (Clause 12) A method for producing silk yarn with increased strength, comprising feeding a substance containing carbon black to silkworms. (Clause 13) A method according to any one of Clauses 5 to 12, comprising producing silk yarn using the silkworms. (Clause 14) A method according to any one of Clauses 5 to 13, comprising allowing the silkworms to spin cocoons to produce cocoons, and producing silk yarn using the cocoons. (Item 15) A silkworm feed according to any one of items 1 to 4, which does not contain carbon nanotubes, graphene, and graphite in substantial amounts.(Item 16) A method for producing silk yarn according to any one of items 5 to 14, wherein the carbon black-containing material does not contain carbon nanotubes, graphene, and graphite in substantial amounts.

[0047] While this disclosure has been described with reference to several embodiments described above, it is not limited to the examples given in those embodiments. Various modifications can be made to the structure and details of this disclosure within the scope of this disclosure.

Claims

1. Silkworm feed containing carbon black.

2. The silkworm feed according to claim 1, wherein the carbon black includes conductive carbon black.

3. A method for producing silk thread, comprising feeding silkworms a substance containing carbon black.

4. The method for producing silk yarn according to claim 3, wherein the substance containing carbon black includes silkworm feed containing carbon black.

Images