Manufacturing method of functional sheet

Abstract

To provide a production method of a functional sheet, capable of producing a functional sheet having high moisture retention.SOLUTION: A production method of a functional sheet comprises a step of forming a mixture by mixing cellulose obtained from cotton and a powder containing sericin, a step of forming a web by depositing the mixture, a step of imparting moisture to the web, and a step of compressing and heating the web with the imparted moisture.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for producing a functional sheet. [Background technology]

[0002] A functional sheet containing sericin has been known for some time. The functional sheet containing sericin has excellent moisture retention properties and is therefore suitable for use in the fields of cosmetics, medicine, and the like.

[0003] For example, Patent Document 1 describes a method for producing skin paper containing sericin produced from silk, in which pulp and hemp are bleached, suspended in water, and an aqueous sericin solution is added to adjust the straining water, which is then removed using a papermaking machine and dried to produce paper. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-50397 Summary of the Invention [Problem to be solved by the invention]

[0005] However, even if sericin is dissolved in water and used to make paper as described in Patent Document 1, most of the sericin will flow out rather than remaining in the fibers because it is easily soluble in water. Therefore, the sheet produced by the method described in Patent Document 1 may not have sufficient moisture retention. [Means for solving the problem]

[0006] One aspect of the method for producing a functional sheet according to the present invention is to A step of mixing cellulose obtained from cotton and a powder containing sericin to form a mixture; depositing the mixture to form a web; adding moisture to the web; applying pressure and heat to the moistened web; Includes. [Brief description of the drawings]

[0007] [Figure 1] 4 is a flowchart for explaining a method for producing a functional sheet according to the present embodiment. [Diagram 2] FIG. 1 is a diagram illustrating a sheet manufacturing apparatus according to an embodiment of the present invention. [Diagram 3] 1 is a table showing the relationship between sericin content and moisture content. [Figure 4] Graph showing the relationship between sericin content and moisture content. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Preferred embodiments of the present invention will be described in detail below with reference to the drawings. Note that the embodiments described below do not unduly limit the contents of the present invention described in the claims. In addition, not all of the configurations described below are necessarily essential components of the present invention.

[0009] 1. Functional Sheet First, the functional sheet according to the present embodiment will be described. The functional sheet according to the present embodiment contains cellulose and a powder containing sericin. Furthermore, the powder may be a powder of silk thread or may contain fibroin. Each component of the functional sheet according to the present embodiment will be described in order below.

[0010] 1.1. Cellulose The cellulose contained in the functional sheet is obtained from cotton. The cellulose may be composed of cotton obtained from cotton. The functional sheet contains cellulose obtained from cotton, and thus has a good feel to the touch. The cellulose contained in the functional sheet is in a fibrous form. The cellulose fibers may be subjected to various surface treatments.

[0011] 1.2. Sericin The sericin contained in the functional sheet is derived from, for example, domesticated silkworms and wild silkworms. Examples of domesticated silkworms and wild silkworms include, for example, mulberry, kanbouju, usubakuwako, indianikuwako, tensan, sakusan, tasar silkworm, muga silkworm, eri silkworm, rederi silkworm, kususan, yonakuni silkworm, cecrobia, cricula, shinjusan, omizuao, usudabiga, rothschild yamamayuga, borosera, marukareha, gonometa, bakipasa, anaphe, hybrids thereof, and genetically modified silkworms. It is particularly preferable that sericin is derived from domesticated silkworms, and the sericin cocoon varieties sericin hope, naked pupa (Nd), and sericin silkworm (Nd-s) are advantageous in that sericin can be efficiently obtained.

[0012] In the functional sheet, the cellulose fibers are bound by sericin. Sericin is a binder for binding the multiple cellulose fibers contained in the functional sheet. Here, "cellulose fibers are bound by sericin" refers to a state in which sericin is disposed between the cellulose fibers, and the cellulose fibers are difficult to separate from each other through the sericin.

[0013] The content of sericin in the functional sheet is, for example, 10% by mass or more and 90% by mass or less, preferably 12.5% ​​by mass or more and 80% by mass or less, and more preferably 20% by mass or more and 50% by mass or less. If the content of sericin in the functional sheet is 10% by mass or more, the moisture retention of the functional sheet can be improved. If the content of sericin in the functional sheet is 90% by mass or less, the deterioration of the feel of the functional sheet can be suppressed.

[0014] The presence of sericin in the functional sheet can be confirmed by, for example, infrared absorption and SEM-EDX (Scanning Electron Microscope-Energy Dispersive X-ray Detector). The content of sericin in the functional sheet can be measured by, for example, hot water extraction, infrared absorption, nuclear magnetic resonance (NMR), X-ray diffraction, and mass spectrometry (MALDI-TOF-MS).

[0015] 1.3. Fibroin The fibroin contained in the functional sheet, like sericin, is derived from, for example, domesticated silkworms and wild silkworms. Domesticated silkworms contain sericin and fibroin. The mass ratio of sericin to fibroin in domesticated silkworms is about 3:7. Fibroin is wrapped around sericin. That is, sericin is present so as to cover fibroin. When the functional sheet contains fibroin, sericin can bond cellulose fibers together via fibroin. This can improve the tensile strength of the functional sheet.

[0016] The inclusion of fibroin in the functional sheet can be confirmed by, for example, infrared absorption spectrometry and SEM-EDX. The content of fibroin in the functional sheet can be measured by, for example, infrared absorption spectrometry, nuclear magnetic resonance spectrometry (NMR), X-ray diffraction, and mass spectrometry (MALDI-TOF-MS).

[0017] 1.4. Shape and uses of functional sheets Because the functional sheet has high moisture retention, it is suitable for use in the fields of cosmetics, medicine, etc. For example, when the functional sheet is used in the field of cosmetics, lotion is applied to the functional sheet, and the functional sheet with the lotion applied thereto is brought into contact with the skin.

[0018] The thickness of the functional sheet is, for example, 0.05 mm or more and 5.0 mm or less. The density of the functional sheet is, for example, 0.5 g / cm 3 More than 1.0g / cm 3 or less, preferably 0.7 g / cm 3 More than 0.9g / cm 3 The following is the result.

[0019] 1.5. Other Additives The fibrous sheet may contain additives other than cellulose fiber, sericin, and fibroin. Examples of additives contained in the fibrous sheet include fillers such as talc and calcium carbonate, paper strength agents such as starch and polyvinyl alcohol (PVA), fluorescent whitening agents, flame retardants, fragrances, antistatic agents, ultraviolet absorbing agents, colorants, aggregation inhibitors, and preservatives.

[0020] 2. Manufacturing method of functional sheets Next, a method for producing a functional sheet according to the present embodiment will be described with reference to the drawings. Fig. 1 is a flow chart for explaining the method for producing a functional sheet according to the present embodiment.

[0021] The method for producing a functional sheet according to the present embodiment includes a mixture forming step (step S1), a web forming step (step S2), a moisture providing step (step S3), and a pressurizing and heating step (step S4), as shown in Fig. 1. Each step will be described below in order.

[0022] 2.1. Mixture formation process In the mixture forming step, cellulose obtained from cotton is mixed with a powder containing sericin to form a mixture. The mixing method is not particularly limited. For example, cellulose fibers and fibroin powder wrapped with sericin can be obtained by defibrating cotton obtained from cotton and cocoon balls, and the mixture is formed by mixing them. The cotton obtained from cotton and the cocoon balls may be defibrated at the same time. This makes it possible to omit a separate step of mixing cellulose fibers and fibroin powder wrapped with sericin. The cotton obtained from cotton and the cocoon balls may be defibrated separately, and the cellulose fibers and fibroin powder wrapped with sericin may be mixed after the defibrating step.

[0023] By using powdered sericin, the amount of sericin added can be easily handled. Furthermore, the mechanism for applying sericin can be simplified, allowing the device to be made more compact. Furthermore, the sericin content in the functional sheet can be increased compared to when an aqueous sericin solution is used. The powder containing sericin does not have to be a powder obtained by defibrating cocoons, and may be, for example, a powder consisting only of powdered sericin.

[0024] The particle size of the powdered sericin is, for example, 5 μm or more and 1000 μm or less. If the particle size of sericin is 5 μm or more, powdered sericin can be easily obtained. If the particle size of sericin is 1000 μm or less, sericin can be prevented from forming lumps, and the tensile strength of the functional sheet can be improved. Note that "particle size" refers to the volume average particle size, and can be measured, for example, using a particle size distribution measuring device "Nanotrac Wave II-EX150" manufactured by MicrotracBEL.

[0025] 2.2. Web forming process In the web forming step, the mixture formed in the mixture forming step is deposited to form a web. The deposition method is not particularly limited. The web has a lower density than the functional sheet and is in a state where the pressurizing and heating step has not been performed. The web is formed, for example, by dropping the mixture through a sieve and depositing the mixture on a mesh belt.

[0026] 2.3. Moisture addition process In the moisture imparting step, moisture is imparted to the web formed in the web forming step. Specifically, in the moisture imparting step, water is imparted to the web. The method of imparting moisture is not particularly limited. When moisture at room temperature is imparted, sericin does not have adhesive properties, but when heated in a moisture-imparted state, sericin softens and exhibits adhesive properties, and can bond a plurality of cellulose fibers. As the water, general tap water or the like can be used, but pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, and distilled water, as well as ultrapure water from which ionic impurities have been removed, can also be used.

[0027] In the moisture imparting step, the amount of moisture imparted is, for example, 30% by mass or more and 200% by mass or less, and preferably 50% by mass or more and 150% by mass or less, based on the web. If the amount of moisture imparted is 30% by mass or more, sericin can have sufficient adhesiveness. If the amount of moisture imparted is 200% by mass or less, it is possible to prevent sericin from flowing out due to excessive moisture.

[0028] In the moisture imparting step, for example, moisture is imparted to the web in the form of steam or liquid. This makes it easy to impart a small amount of moisture as needed. When moisture is imparted in the form of liquid, water may be sprayed.

[0029] 2.4. Pressurization and heating process In the pressurizing and heating step, the web to which moisture has been added in the moisture adding step is pressurized and heated. By heating the web to which moisture has been added, the sericin softens and develops adhesiveness, thereby binding multiple cellulose fibers together. The moisture added in the moisture adding step evaporates due to the heat in the pressurizing and heating step.

[0030] In the pressurizing and heating step, for example, the web is pressurized and heated by a heat press or a roller. In the pressurizing and heating step, the web may be pressurized and then heated, or the web may be pressurized and heated simultaneously. If the web is pressurized and heated simultaneously, the process can be simplified.

[0031] In the pressurizing and heating step, the mixture is pressurized at a pressure of, for example, 5 Pa to 200 MPa, preferably 10 MPa to 100 MPa, thereby making it possible to form a functional sheet that is pleasant to the touch.

[0032] In the pressurizing and heating step, the mixture is heated at a temperature of, for example, 40° C. to 100° C., preferably 50° C. to 90° C. Heating at a temperature of 40° C. or higher can cause the sericin to develop adhesiveness. Heating at a temperature of 100° C. or lower can reduce the power consumption of the device.

[0033] 2.5. Other processes The method for producing a functional sheet according to the present embodiment may include steps other than the steps described above. Examples of steps included in the method for producing a functional sheet according to the present embodiment include a step of selecting cellulose fibers using a sieve, and a step of cutting the functional sheet to a predetermined size after the pressurizing and heating step.

[0034] 2.6. Effects The method for producing a functional sheet according to the present embodiment includes the steps of mixing cellulose obtained from cotton with a powder containing sericin to form a mixture, piling the mixture to form a web, adding moisture to the web, and pressurizing and heating the web to which moisture has been added. Therefore, compared to the case where sericin is dissolved in water and paper is made by dissolving it in water, sericin is less likely to dissolve and flow out, and the content of sericin in the functional sheet can be increased. Therefore, the moisture retention can be improved. Furthermore, by using cellulose obtained from cotton, the moisture retention can be further improved and a functional sheet with a pleasant texture can be produced. Thus, the functional sheet produced by the method for producing a functional sheet according to the present embodiment is highly moisture retaining and pleasant to the touch, and is therefore particularly effective for cosmetic applications.

[0035] In the method for producing a functional sheet according to the present embodiment, the powder is a powder of cocoon filaments. Therefore, the powder obtained by directly defibrating the cocoon filaments can be used as the powder containing sericin.

[0036] In the method for producing a functional sheet according to the present embodiment, the powder contains fibroin covered with sericin, and therefore, the cellulose fibers are bonded to each other via the fibroin covered with sericin, so that a functional sheet with high tensile strength can be produced.

[0037] In the method for producing a functional sheet according to the present embodiment, the content of sericin in the functional sheet is 10% by mass or more, so that a functional sheet with a high content of sericin can be produced.

[0038] In the method for producing a functional sheet according to the present embodiment, the amount of moisture added in the moisture-adding step is 200% by mass or less based on the web, which can prevent sericin from flowing out due to excessive moisture.

[0039] In the method for producing a functional sheet according to the present embodiment, in the step of adding moisture, moisture is added in the form of water vapor or liquid. This makes it easy to add only a small amount of moisture as needed. In addition, sericin is less likely to dissolve in water and flow out, so the sericin content in the functional sheet can be increased. Therefore, a functional sheet with high moisture retention can be produced.

[0040] 3. Sheet manufacturing equipment Next, the sheet manufacturing apparatus according to the present embodiment will be described with reference to the drawings. Fig. 2 is a schematic diagram of the sheet manufacturing apparatus 100 according to the present embodiment. The above-described method for manufacturing a functional sheet according to the present embodiment is carried out by using the sheet manufacturing apparatus 100, for example.

[0041] As shown in FIG. 2, the sheet manufacturing apparatus 100 includes, for example, a supply section 10, a coarse crushing section 12, a defibrating section 20, a sorting section 40, a first web forming section 45, a rotating body 49, a mixing section 50, a deposition section 60, a second web forming section 70, a moisture imparting section 78, a sheet forming section 80, and a cutting section 90.

[0042] The supply unit 10 supplies the raw material to the crushing unit 12. The supply unit 10 is, for example, an automatic supply unit for continuously supplying the raw material to the crushing unit 12. The raw material supplied by the supply unit 10 is cotton obtained from cotton bolls.

[0043] The crushing unit 12 cuts the raw material supplied by the supply unit 10 into small pieces in air, such as the atmosphere. The small pieces have a shape and size of, for example, several centimeters square. In the example shown in the figure, the crushing unit 12 has crushing blades 14, which can cut the input raw material. For example, a shredder is used as the crushing unit 12. The raw material cut by the crushing unit 12 is received in a hopper 1 and then transferred to the defibrating unit 20 via a pipe 2.

[0044] The defibrating unit 20 forms defibrated material by defibrating the raw material cut by the crushing unit 12. As a result, the raw cotton material is in a state where the cellulose fibers are untangled into individual strands.

[0045] The defibrator unit 20 performs defibration in a dry manner. Here, the term "dry manner" refers to performing defibration and other processes in air, such as in the atmosphere, rather than in a liquid. For example, an impeller mill is used as the defibrator unit 20. The defibrator unit 20 has a function of generating an airflow that sucks in the raw material and discharges the defibrated material. This allows the defibrator unit 20 to suck in the raw material together with the airflow from the inlet 22 using the airflow it generates, defibrate the raw material, and transport the defibrated material to the outlet 24. The defibrated material that has passed through the defibrator unit 20 is transferred to the sorting unit 40 via the pipe 3. The airflow for transporting the defibrated material from the defibrator unit 20 to the sorting unit 40 may be the airflow generated by the defibrator unit 20, or an airflow generating device such as a blower may be provided and the airflow may be used.

[0046] The sorting unit 40 introduces the defibrated material defibrated by the defibration unit 20 from an inlet 42 and sorts it according to the length of the cellulose fibers. The sorting unit 40 has, for example, a drum unit 41 and a housing unit 43 that houses the drum unit 41. For example, a sieve is used as the drum unit 41. The drum unit 41 has a net and can separate cellulose fibers smaller than the mesh size of the net, i.e., a first sorted material that passes through the net, from cellulose fibers larger than the mesh size of the net, undefibrated pieces, and lumps, i.e., a second sorted material that does not pass through the net. For example, the first sorted material is transferred to the deposition unit 60 via a pipe 7. The second sorted material is returned to the defibration unit 20 from a discharge port 44 via a pipe 8. Specifically, the drum unit 41 is a cylindrical sieve that is rotated by a motor. The mesh of the drum portion 41 may be, for example, a wire mesh, an expanded metal made by stretching a metal plate with slits, or a punched metal made by forming holes in a metal plate using a press or the like.

[0047] The first web forming unit 45 conveys the first sorted material that has passed through the sorting unit 40 to the pipe 7. The first web forming unit 45 has, for example, a mesh belt 46, a tension roller 47, and a suction mechanism 48.

[0048] The suction mechanism 48 can suck the first sorted material, which has passed through the openings of the sorting unit 40 and been dispersed in the air, onto the mesh belt 46. The first sorted material is deposited on the moving mesh belt 46 to form a web V. The basic configurations of the mesh belt 46, the tension roller 47, and the suction mechanism 48 are similar to those of the mesh belt 72, the tension roller 74, and the suction mechanism 76 of the second web forming unit 70, which will be described later.

[0049] The web V is formed into a soft and puffy state containing a lot of air by passing through the screening unit 40 and the first web forming unit 45. The web V accumulated on the mesh belt 46 is input into the pipe 7 and transported to the accumulation unit 60.

[0050] The rotating body 49 can cut the web V. In the illustrated example, the rotating body 49 has a base 49a and protrusions 49b protruding from the base 49a. The protrusions 49b have, for example, a plate-like shape. In the illustrated example, four protrusions 49b are provided, and the four protrusions 49b are provided at equal intervals. By rotating the base 49a in the direction R, the protrusions 49b can rotate around the base 49a as an axis. By cutting the web V with the rotating body 49, for example, it is possible to reduce the fluctuation in the amount of defibrated material supplied per unit time to the deposition section 60.

[0051] The rotating body 49 is provided in the vicinity of the first web forming section 45. In the illustrated example, the rotating body 49 is provided in the vicinity of the tension roller 47a located downstream in the path of the web V. The rotating body 49 is provided in a position where the protrusions 49b can contact the web V but do not contact the mesh belt 46 on which the web V is deposited. This makes it possible to prevent the mesh belt 46 from being worn by the protrusions 49b. The shortest distance between the protrusions 49b and the mesh belt 46 is, for example, 0.05 mm or more and 0.5 mm or less. This is the distance at which the web V can be cut without damaging the mesh belt 46.

[0052] The mixing section 50 mixes the first sorted material that has passed through the sorting section 40 with a powder containing sericin. The mixing section 50 has, for example, a powder supplying section 52 that supplies the powder containing sericin, a pipe 54 that transports the first sorted material and the powder, and a blower 56. In the example shown in the figure, the powder is supplied from the powder supplying section 52 to the pipe 54 via a hopper 9. The pipe 54 is continuous with the pipe 7.

[0053] In the mixing section 50, an air flow is generated by a blower 56, and the first sorted material and the powder containing sericin can be transported while being mixed in the pipe 54. The mechanism for mixing the first sorted material and the powder is not particularly limited, and may be one that uses a blade that rotates at high speed to mix, or one that utilizes the rotation of a container such as a V-type mixer.

[0054] 2 or a disk feeder (not shown) is used as the powder supplying unit 52. The powder supplied from the powder supplying unit 52 may contain fibroin in addition to sericin.

[0055] The additives supplied from the powder supply unit 52 may include, in addition to sericin and fibroin that bind the cellulose fibers, a colorant for coloring the cellulose fibers, an aggregation inhibitor for inhibiting aggregation of the cellulose fibers and aggregation of the resin, and a flame retardant for making the cellulose fibers, etc., less flammable, depending on the type of functional sheet to be manufactured. The mixture that has passed through the mixing unit 50 is transferred to the deposition unit 60 via a pipe 54.

[0056] The deposition section 60 introduces the mixture that has passed through the mixing section 50 from an inlet 62, loosens the tangled mixture, and causes it to fall while being dispersed in the air.

[0057] The deposition unit 60 has, for example, a drum unit 61 and a housing unit 63 that houses the drum unit 61. A rotating cylindrical sieve is used as the drum unit 61. The drum unit 61 has a mesh and causes cellulose fibers or particles that are contained in the mixture that has passed through the mixing unit 50 and are smaller than the size of the mesh openings to fall. The configuration of the drum unit 61 is the same as that of the drum unit 41, for example.

[0058] The "sieve" of the drum unit 61 does not have to have the function of separating out a specific object. In other words, the "sieve" used as the drum unit 61 means one equipped with a net, and the drum unit 61 may allow all of the mixture introduced into the drum unit 61 to fall.

[0059] The mixture that has passed through the deposition unit 60 is deposited in the second web forming unit 70 to form a web W. The second web forming unit 70 has, for example, a mesh belt 72, a tension roller 74, and a suction mechanism 76.

[0060] The mixture that has passed through the openings of the deposition section 60 is deposited on the mesh belt 72. The mesh belt 72 is stretched by tension rollers 74, and is configured to prevent the mixture from passing through but allow air to pass through. The mesh belt 72 moves as the tension rollers 74 rotate. As the mesh belt 72 moves continuously, the mixture that has passed through the deposition section 60 continuously falls and accumulates, forming a web W on the mesh belt 72.

[0061] The suction mechanism 76 is provided below the mesh belt 72. The suction mechanism 76 can generate a downward airflow. The suction mechanism 76 can suck the mixture dispersed in the air by the deposition unit 60 onto the mesh belt 72. This can increase the discharge speed from the deposition unit 60. Furthermore, the suction mechanism 76 can form a downflow in the falling path of the mixture, preventing the cellulose fibers from becoming entangled during the fall. By passing through the deposition unit 60 and the second web forming unit 70, a web W that contains a lot of air and is soft and puffy is formed.

[0062] The moisture applying unit 78 applies water to the web W on the mesh belt 72. The moisture applying unit 78 is not particularly limited as long as it can apply moisture, and may be, for example, a spray. Then, the web W is transported to the sheet forming unit 80.

[0063] The sheet forming unit 80 pressurizes and heats the moisture-added web W to form a functional sheet S. The sheet forming unit 80 has a pressurizing unit 82 that pressurizes the web W, and a heating unit 84 that heats the web W pressurized by the pressurizing unit 82.

[0064] The pressure unit 82 is formed of, for example, a pair of calender rollers 85, and applies pressure to the web W. When the web W is pressed, its thickness decreases and the density of the web W increases.

[0065] The heating unit 84 may be, for example, a heating roller, a heat press molding machine, a hot plate, a hot air blower, an infrared heater, or a flash fixing device. In the illustrated example, the heating unit 84 has a pair of heating rollers 86. By configuring the heating unit 84 as the heating rollers 86, the functional sheet S can be formed while continuously conveying the web W, compared to the case where the heating unit 84 is configured as a plate-shaped press device. By being heated by the heating unit 84, the sericin softens and develops adhesiveness, and binds a plurality of cellulose fibers. The moisture applied to the web W is evaporated by the heating of the heating unit 84. The calendar roller 85 and the heating roller 86 are arranged, for example, so that their rotation axes are parallel. The calendar roller 85 can apply a pressure to the web W that is higher than the pressure applied to the web W by the heating roller 86. The number of the calendar rollers 85 and the heating rollers 86 is not particularly limited.

[0066] The cutting unit 90 cuts the functional sheet S formed by the sheet forming unit 80. In the illustrated example, the cutting unit 90 has a first cutting unit 92 that cuts the functional sheet S in a direction intersecting the conveying direction of the functional sheet S, and a second cutting unit 94 that cuts the functional sheet S in a direction parallel to the conveying direction. The second cutting unit 94 cuts the functional sheet S that has passed through the first cutting unit 92, for example.

[0067] In this manner, a single piece of functional sheet S having a predetermined size is formed. The cut single piece of functional sheet S is discharged to a discharge section 96.

[0068] In the method for producing a functional sheet according to the present embodiment described above, the mixture forming step is performed, for example, by using the mixing unit 50. The web forming step is performed, for example, by using the deposition unit 60 and the second web forming unit 70. The moisture imparting step is performed, for example, by using the moisture imparting unit 78. The pressurizing and heating step is performed, for example, by using the sheet forming unit 80.

[0069] In the above, an example has been described in which powder containing sericin is supplied from the powder supply unit 52, but for example, cotton obtained from cotton and cocoon balls may be input as raw materials into the supply unit 10. In this case, cellulose fibers and powder containing sericin can be obtained as the defibrated material. In this case, the powder supply unit 52 does not need to be provided.

[0070] 4. Experimental Example 4.1. Preparation of functional sheet The cotton obtained from cotton and the cocoon balls were defibrated separately. Next, the defibrated cotton and the defibrated cocoon balls were mixed and passed through a sieve with a mesh size of 15 mm square to deposit the mixture to form a web. The web was sprayed with water in an amount equal to the mass of the web using a spray. It was then pressed for 30 seconds at a temperature of 70°C and a pressure of 20 MPa using a hot press to obtain a functional sheet. When the defibrated cocoon balls were subjected to hot water extraction, the sericin content was 25% by mass. The sericin content in the functional sheet was changed by changing the mixing ratio of the defibrated cotton and the defibrated cocoon balls.

[0071] 4.2. Moisture content measurement The moisture content of the functional sheet was measured. Specifically, the functional sheet was left in a container at 25℃ and 100% RH (relative humidity) for 4 hours to absorb moisture. Then, the moisture content of the functional sheet was measured immediately after it was removed from the container. The moisture content was measured using the "MX-50 heat and dry moisture meter" manufactured by A&D Co., Ltd.

[0072] Figure 3 is a table showing the relationship between sericin content and moisture content. Figure 4 is a graph showing the relationship between sericin content and moisture content, plotting the values ​​in the table shown in Figure 3. As shown in Figures 3 and 4, it was found that the higher the sericin content in the functional sheet, the higher the moisture content. In other words, it was found that functional sheets containing a large amount of sericin have high moisture retention.

[0073] The present invention includes configurations that are substantially the same as the configurations described in the embodiments, for example, configurations with the same functions, methods, and results, or configurations with the same purpose and effects. The present invention also includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. The present invention also includes configurations that achieve the same effects as the configurations described in the embodiments, or configurations that can achieve the same purpose. The present invention also includes configurations in which publicly known technology is added to the configurations described in the embodiments.

[0074] The following can be derived from the above-described embodiment.

[0075] One aspect of the method for producing a functional sheet is to A step of mixing cellulose obtained from cotton and a powder containing sericin to form a mixture; depositing the mixture to form a web; adding moisture to the web; applying pressure and heat to the moistened web; Includes.

[0076] According to this method for producing a functional sheet, sericin is less likely to dissolve in water and flow out than when sericin is dissolved in water to make paper, and the content of sericin in the functional sheet can be increased, so that a functional sheet with high moisture retention can be produced.

[0077] In one embodiment of the method for producing a functional sheet, The powder may be silk filament powder.

[0078] According to this method for producing a functional sheet, the powder obtained by directly defibrating the cocoon filaments can be used as the powder containing sericin.

[0079] In one embodiment of the method for producing a functional sheet, The powder may include fibroin wrapped around the sericin.

[0080] According to this method of producing a functional sheet, the cellulose fibers are bonded to each other via the fibroin covered with sericin, so that a functional sheet with high tensile strength can be produced.

[0081] In one embodiment of the method for producing a functional sheet, The content of the sericin in the functional sheet may be 10% by mass or more.

[0082] According to this method for producing a functional sheet, a functional sheet having a high sericin content can be produced.

[0083] In one embodiment of the method for producing a functional sheet, In the step of applying moisture, the amount of moisture applied may be 200% by mass or less with respect to the web.

[0084] According to this method for producing a functional sheet, it is possible to prevent sericin from flowing out due to excessive moisture.

[0085] In one embodiment of the method for producing a functional sheet, In the step of applying moisture, the moisture may be applied in the form of water vapor or liquid.

[0086] According to this method for producing a functional sheet, it is easy to add a small amount of moisture as needed. Also, sericin is less likely to dissolve in water and flow out, so the content of sericin in the functional sheet can be increased. Therefore, a functional sheet with high moisture retention can be produced. [Explanation of symbols]

[0087] Reference Signs List 1...hopper, 2,3,7,8...pipe, 9...hopper, 10...supply section, 12...crushing section, 14...crushing blade, 20...defibration section, 22...inlet, 24...discharge outlet, 40...screening section, 41...drum section, 42...inlet, 43...housing section, 44...discharge outlet, 45...first web forming section, 46...mesh belt, 47,47a...tension roller, 48...suction mechanism, 49...rotating body, 49a...base, 49b...projection, 50...mixing section, 52...powder supply section , 54... pipe, 56... blower, 60... deposition section, 61... drum section, 62... inlet, 63... housing section, 70... second web forming section, 72... mesh belt, 74... tension roller, 76... suction mechanism, 78... moisture adding section, 80... sheet forming section, 82... pressure section, 84... heating section, 85... calendar roller, 86... heating roller, 90... cutting section, 92... first cutting section, 94... second cutting section, 96... discharge section, 100... sheet manufacturing apparatus

Claims

1. Cellulose obtained from cotton is mixed with a powder containing sericin to form a mixture. The process and depositing the mixture to form a web; adding moisture to the web; applying pressure and heat to the moistened web; A method for producing a functional sheet comprising the steps of:

2. In claim 1, The method for producing a functional sheet, wherein the powder is a powder of silk thread.

3. In claim 1 or 2, The method for producing a functional sheet, wherein the powder contains fibroin wrapped around the sericin.

4. In any one of claims 1 to 3, The content of the sericin in the functional sheet is 10% by mass or more. A method for manufacturing the sheet.

5. In any one of claims 1 to 4, In the step of applying moisture, the amount of moisture applied is 200 mass % relative to the web. A method for producing a functional sheet, wherein the content of the polymer in the functional sheet is less than or equal to 10% by weight.

6. In any one of claims 1 to 5, In the step of adding moisture, the moisture is added in the form of water vapor or liquid. A method for manufacturing a functional sheet.

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