Preparation method and application of antibacterial and mildew-proof agent for spinning

Abstract

The invention discloses a preparation method and application of an antibacterial and mildew-proof agent for spinning and relates to the field of home textiles. The preparation method of the antibacterial and mildew-proof agent for spinning comprises the following steps: step 1, heating and refluxing theanine powder, a loading material and absolute ethyl alcohol, and evaporating a solvent to dryness to obtain a loaded antibacterial agent material; step 2, grinding and crushing the supported antibacterial agent material to obtain a primary product of the antibacterial and mildew-proof agent for the second time; step 3, uniformly mixing the primary antibacterial and mildew-proof agent product, nano zinc oxide powder, IPBC and an adhesive to obtain a mixture; step 4, ball-milling the mixture and silicon dioxide sol to obtain a ball-milled mixture; step 5, mixing the ball-milled mixture and a polyvinyl alcohol aqueous solution, and then adding a cross-linking agent and a defoaming agent to obtain an injection molding material; and step 6, curing, sintering, cooling, grinding and crushing the injection molding material to obtain the antibacterial and mildew-proof agent for spinning. The composite flocculus using the antibacterial and mildew-proof agent for spinning not only is antibacterial and mildew-proof, but also has excellent heat retention property and air permeability.

Description

Technical Field

[0001] The present invention relates to the field of home textiles, and in particular to antibacterial and mildew-proof agents. Background Art

[0002] Although the common cotton wadding sheets in the current market have good warmth retention and comfort, they are prone to breeding bacteria and molds during long-term use and storage, resulting in the generation of odors and affecting the hygienic performance, warmth retention performance and service life of the products. Summary of the Invention

[0003] The purpose of the present invention is to provide a preparation method of an antibacterial and mildew-proof agent for textiles to prepare an antibacterial and mildew-proof agent for textiles.

[0004] The purpose of the present invention is also to provide a preparation method of antibacterial and mildew-proof cotton fibers to prepare antibacterial and mildew-proof cotton fibers.

[0005] The purpose of the present invention is also to provide a preparation method of an antibacterial and mildew-proof cotton wadding sheet to prepare a cotton wadding sheet that can solve the above problems.

[0006] The purpose of the present invention is also to provide a preparation method of a composite wadding sheet with an air sandwich to prepare a composite wadding sheet that can solve the above problems.

[0007] The technical problems solved by the present invention can be achieved by the following technical solutions:

[0008] A preparation method of an antibacterial and mildew-proof agent for textiles, characterized by including the following steps:

[0009] Step 1, after mixing the theanine powder and the loading material evenly, adding absolute ethanol to fully infiltrate, then heating under reflux for 24 h - 48 h, and then evaporating the solvent to obtain a loaded antibacterial agent material;

[0010] Step 2, after grinding and pulverizing the loaded antibacterial agent material, heating it to 200°C - 230°C for the first time and holding for 2 h - 4 h, and then heating it to 380°C - 400°C for the second time and holding for 5 h - 8 h to obtain a preliminary product of the antibacterial and mildew-proof agent;

[0011] Step 3, mixing the preliminary product of the antibacterial and mildew-proof agent, nano-zinc oxide powder, IPBC, and binder evenly to obtain a mixture;

[0012] Step 4, putting the mixture and silica sol into a ball mill and ball milling for 5 h - 8 h to obtain a ball-milled mixture;

[0013] Step 5: Mix the ball-milled mixture and the polyvinyl alcohol aqueous solution, mechanically stir at a speed of 500 r / min - 1000 r / min for 20 min - 30 min, then add a cross-linking agent, mechanically stir at a speed of 1200 r / min - 1500 r / min for 15 min - 30 min, then add an antifoaming agent, and mechanically stir at a uniform speed for 8 min - 10 min. After removing the air in the mixture under negative pressure, a casting material is obtained.

[0014] Step 6: Inject the casting material into a mold, dry it at 90°C - 100°C to cure the casting material into a block; then, transfer it to an electric resistance furnace, heat it to 300°C - 320°C in a nitrogen atmosphere and sinter for 4 h - 5 h; then, after cooling to room temperature, take it out and grind it to obtain an antibacterial and mildew-proof agent for textiles.

[0015] Preferably, in Step 1, the loading material is diatomite powder with a particle size of 10 μm - 20 μm.

[0016] Preferably, in Step 5, the polyvinyl alcohol aqueous solution is a polyvinyl alcohol aqueous solution with a mass concentration of 10%.

[0017] Preferably, in Step 1, the mass ratio of the theanine powder to the diatomite powder is 1 - 3:1, and the absolute ethanol accounts for 10% - 30% of the total mass; in Step 3, the mass ratio of the preliminary product of the antibacterial and mildew-proof agent, nano-zinc oxide powder, IPBC, and binder is 5:1 - 2:2 - 1:2; in Step 4, the mass ratio of the mixture to the silica sol is 2:3; in Step 5, the polyvinyl alcohol aqueous solution with a mass concentration of 10% accounts for 5% - 10% of the total mass; the cross-linking agent accounts for 1% of the total mass, and the antifoaming agent accounts for 0.1% - 0.5% of the total mass.

[0018] A method for preparing antibacterial and mildew-proof cotton fibers, characterized in that an antibacterial and mildew-proof agent for textiles is added to raw cotton fibers to obtain antibacterial and mildew-proof cotton fibers.

[0019] Specifically, it includes the following steps:

[0020] Step a: Immerse the raw cotton fibers in an aqueous solution containing cellulase, hemicellulase, and pectinase, and perform an oscillation treatment. At the same time, heat it to 45°C at a heating rate of 5°C / min and keep it warm for 3 h - 4 h.

[0021] Step b: Rinse the raw cotton fibers treated in Step a with hot water at 40°C - 50°C.

[0022] Step c, adding acid and water to the rinsed lint cotton fiber, adjusting the pH value to 5.5-7.5, adding an aqueous solution containing 5g / L-8g / L of an antibacterial and mildew-proof agent for textile use, controlling the bath ratio at 1:6, shaking and impregnating for 15min-20min, and then dehydrating to obtain antibacterial and mildew-proof cotton fiber.

[0023] Preferably, in step a, the weight of cellulase is 1%-3% of the weight of the lint fiber, the weight of hemicellulase is 1%-3% of the weight of the lint fiber, and the weight of pectinase is 1%-2% of the weight of the lint fiber.

[0024] Preferably, a refining agent is further added to the aqueous solution in step a, and the refining agent is one or more of sodium dodecylbenzene sulfonate, sodium secondary alkyl sulfonate, nonylphenol polyoxyethylene ether, and isomeric alcohol ether carboxylates.

[0025] The method for preparing the antibacterial and mildew-proof cotton wool sheet is characterized by comprising the following steps: opening and combing the antibacterial and mildew-proof cotton fibers to obtain the antibacterial and mildew-proof cotton wool sheet.

[0026] The preparation method of the composite flakes with air interlayers is characterized by comprising the following steps: ① preliminarily opening the antibacterial and mildew-proof cotton fiber, theanine lyocell fiber, PCM viscose fiber, and low-melting-point fiber through a wool blending machine, and then finely opening the fibers until the fibers are broken into a loose state;

[0027] Step ②, the antibacterial and mildew-proof cotton fiber, theanine lyocell fiber and low-melting-point fiber treated in step ① are put into a mixer and fully mixed to obtain an upper layer material; at the same time, the PCM viscose fiber and the antibacterial and mildew-proof cotton fiber treated in step ① are put into a mixer and fully mixed to obtain a lower layer material;

[0028] Step ③, use a carding machine to card the upper layer of material, and then cross-lay the fiber web with α as the laying angle to form an upper layer of flakes; at the same time, use a carding machine to card the lower layer of material, and then continuously fold, pile and lay the fiber web to form a lower layer of flakes;

[0029] Step ④: Place the upper flake layer on the lower flake layer, and then melt-bond the two layers of fiber web at the contact surface to obtain a composite flake with an air interlayer.

[0030] Beneficial effects:

[0031] 1. Highly effective antibacterial and mildew-proof performance: The present invention uses a specific preparation process to effectively load and combine theanine, PCM (phase change material) and antibacterial and mildew-proof agents into the fiber, so that the final composite flake product has significant antibacterial and mildew-proof performance. This performance improvement not only helps to extend the service life of the product, but also effectively prevents the growth of bacteria and mildew, providing users with a healthier and safer use environment.

[0032] 2. Excellent warmth retention and breathability: The theanine lyocell fiber and PCM viscose fiber in the composite batting have good moisture absorption and breathability. At the same time, the PCM material can absorb or release heat when the temperature changes, providing continuous warmth retention effect. The addition of the low-melting-point fiber enhances the binding force between the fiber webs, making the entire batting structure more stable and the warmth retention performance more prominent. The cross-laying technology further improves the breathability and structural stability of the batting.

[0033] 3. Environmental protection and sustainability: The fiber raw materials used in the present invention, such as theanine lyocell fiber, PCM viscose fiber and antibacterial and mildew-proof cotton fiber, etc., are all environmentally friendly materials, and harmful chemical emissions are reduced during the preparation process, meeting the green and environmental protection concepts of modern society. In addition, these materials are also renewable, contributing to the sustainable development of the textile industry. Detailed implementation manners

[0034] In order to make the technical means, creative features, achieved purposes and effects of the present invention easy to understand, the present invention will be further elaborated below.

[0035] A preparation method of an antibacterial and mildew-proof agent for textiles, characterized by comprising the following steps:

[0036] Step 1, after uniformly mixing the theanine powder with the loading material (preferably, mechanically stirring at a speed of 500 - 1000 r / min for 30 - 60 min to mix evenly), adding absolute ethanol to fully infiltrate, and then heating under reflux for 24 h - 48 h (the purpose is to effectively load the antibacterial agent on the carrier), and then evaporating the solvent to obtain the supported antibacterial agent material. The loading material can be diatomite powder, silica, activated carbon, etc. Preferably, it is diatomite powder with a particle size of 10 μm - 20 μm. The mass ratio of the theanine powder to the diatomite powder is 1 - 3:1. Preferably, the absolute ethanol accounts for 10% - 30% of the total mass.

[0037] Step 2, after grinding and pulverizing the supported antibacterial agent material, heating it to 200°C - 230°C for the first time and holding for 2 h - 4 h, and then heating it to 380°C - 400°C for the second time and holding for 5 h - 8 h to obtain the preliminary product of the antibacterial and mildew-proof agent. The present invention can effectively enhance the stability of the material by the two-step heating method.

[0038] Step 3: Uniformly mix the preliminary product of the antibacterial and mildew-proof agent, nano-zinc oxide powder, IPBC (IPBC, full name: n-butyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, appearance: white crystalline powder, an organic compound, mainly used as a broad-spectrum, highly efficient bactericidal, antiseptic, and mildew-proof agent), and the binder to obtain a mixed material. Preferably, the mass ratio of the preliminary product of the antibacterial and mildew-proof agent, nano-zinc oxide powder, IPBC, and the binder is 5:1 - 2:2 - 1:2.

[0039] Step 4: Put the mixed material and silica sol into a ball mill and ball mill for 5h - 8h to obtain a ball-milled mixed material. Preferably, the mass ratio of the mixed material to silica sol is 2:3; the ball-milling medium is preferably alloy balls or steel balls with a diameter between 20mm - 100mm. The mass ratio of the ball-milling medium, the mixed material, and silica sol is 5:2:3. Ball milling can make each component fully dispersed and uniformly mixed.

[0040] Step 5: Mix the ball-milled mixed material with an aqueous solution of polyvinyl alcohol, mechanically stir at a speed of 500r / min - 1000r / min for 20min - 30min, then add a cross-linking agent, mechanically stir at a speed of 1200r / min - 1500r / min for 15min - 30min, then add an antifoaming agent, and uniformly mechanically stir for 8min - 10min. After removing the air in the mixed material under negative pressure, an injection molding material is obtained. Preferably, the aqueous solution of polyvinyl alcohol is an aqueous solution of polyvinyl alcohol with a mass concentration of 10%. The aqueous solution of polyvinyl alcohol with a mass concentration of 10% accounts for 5% - 10% of the total mass; the mass ratio of the cross-linking agent to the total mass is 1%, and the mass ratio of the total mass of the antifoaming agent to the total mass is 0.1% - 0.5%.

[0041] Step 6: Inject the injection molding material into a mold and dry it at 90°C - 100°C to cure the injection molding material into a block. The mold can be placed in a vacuum oven and dried using the vacuum oven. Then, transfer it to an electric resistance furnace and heat it up to 300°C - 320°C in a nitrogen atmosphere and sinter for 4h - 5h. This step can form a firm bond between the components of the antibacterial and mildew-proof agent. Then, after cooling to room temperature, take it out and grind it to obtain an antibacterial and mildew-proof agent for textiles.

[0042] Method for preparing antibacterial and mildew-proof cotton fibers: Add the antibacterial and mildew-proof agent for textiles to raw cotton fibers to obtain antibacterial and mildew-proof cotton fibers.

[0043] Specifically, it includes the following steps: Step a, immerse the lint fiber in an aqueous solution containing cellulase, hemicellulase, and pectinase, and perform oscillating treatment. At the same time, heat it to 45°C at a heating rate of 5°C / min and keep it warm for 3H - 4H. Preferably, the weight of cellulase is 1% - 3% of the weight of the lint fiber, the weight of hemicellulase is 1% - 3% of the weight of the lint fiber, and the weight of pectinase is 1% - 2% of the weight of the lint fiber. The amount of water is sufficient to immerse the lint fiber. This step aims to effectively remove the impurities and grease on the surface of the lint fiber through the combined action of the refined enzymes, control the loss of cotton fiber as much as possible, and improve its fiber structure, laying a good foundation for subsequent treatment. A refining agent can be added to the aqueous solution. Preferably, the refining agent is one or more of sodium dodecylbenzenesulfonate, secondary alkyl sulfonate, nonylphenol polyoxyethylene ether, and isomeric alcohol ether carboxylate. Alternatively, the lint fiber after step 2 treatment can be added to an aqueous solution containing a refining agent for further treatment. To further improve the removal degree of impurities and grease on the surface of the lint fiber and improve the performance of the lint fiber to facilitate the subsequent steps.

[0044] Step b, rinse the lint fiber treated in step a with hot water at 40°C - 50°C. Preferably, rinse it in a cleaning device for 5min - 10min, drain the residual liquid, and circulate several times until the color of the residual liquid after rinsing is close to clear, indicating that the impurities and unreacted chemicals on the fiber surface have been fully removed. Subsequently, press and drain the lint fiber to ensure that the excess water is effectively drained.

[0045] Step c, add acid and water to the rinsed lint fiber. Preferably, the acid for adjusting the pH is one or more of citric acid, acetic acid, and oxalic acid. This helps to stabilize the chemical properties of the fiber and create favorable conditions for subsequent antibacterial and mildew-proof treatment. After adjusting the pH value to 5.5 - 7.5, add an aqueous solution containing 5g / L - 8g / L of textile antibacterial and mildew-proof agent, control the bath ratio at 1:6 (i.e., the ratio of lint fiber to treatment liquid), perform oscillating impregnation for 15min - 20min, and then perform dehydration treatment to obtain antibacterial and mildew-proof cotton fiber. This step aims to endow the lint fiber with high antibacterial and mildew-proof performance through the penetration of the antibacterial and mildew-proof agent. During dehydration treatment, preferably, the dehydrated lint fiber is sent into the inlet of a tower-type cotton dryer through a conveyor belt, and try to distribute it evenly during loading. There is a flipping device in the drying tower to ensure that the lint fiber can be continuously flipped and moved during the drying process. The flipping rate is set at 30rpm - 50rpm, the maximum single drying volume of the drying tower is 1000kg of dry cotton, and the drying temperature is set at 80°C - 100°C until the moisture content of the lint fiber reaches 6.5% - 8%.

[0046] A method for preparing an antibacterial and mildew-proof cotton flake, characterized by including the following steps: performing carding treatment on the antibacterial and mildew-proof cotton fiber to obtain an antibacterial and mildew-proof cotton flake.

[0047] The preparation method of a composite flake with an air interlayer is characterized in that it comprises the following steps: Step ① Preliminary opening of antibacterial and mildew-proof cotton fiber, theanine lyocell fiber, PCM viscose fiber, and low-melting point fiber by a wool blending machine, followed by fine opening treatment until the fibers are broken up into a loose state.

[0048] Step ②, the antibacterial and mildew-proof cotton fiber, theanine lyocell fiber and low-melting point fiber treated in step ① are put into a mixer and fully mixed to obtain the upper material. Preferably, the mass of the antibacterial and mildew-proof cotton fiber accounts for 50-60%, and the mass of theanine lyocell fiber and low-melting point fiber accounts for 40-50%. At the same time, the PCM viscose fiber treated in step ① and the antibacterial and mildew-proof cotton fiber are put into a mixer and fully mixed to obtain the lower material. Preferably, the mass of PCM viscose fiber accounts for 40-50% and the mass of another part of the antibacterial and mildew-proof cotton fiber accounts for 50-60%.

[0049] Step ③, use a carding machine to card the upper material so that its fibers are arranged in parallel and laid into the first fiber web. Then, the fiber web is laid crosswise at a laying angle of α (preferably 90°<α<150°) to form an upper layer of flakes. The flakes formed in this way have excellent stability and air permeability. At the same time, use a carding machine to card the lower material, and then continuously fold, pile and lay the fiber web to form a lower layer of flakes, so that the lower layer of flakes has a certain thickness and density.

[0050] Step ④, place the upper layer of the flakes on the lower layer of the flakes, and then melt-bond the two layers of fiber webs at the contact surface to obtain a composite flake with an air interlayer. The two layers of fiber webs can be melt-bonded at the contact surface by means of thermal welding technology, such as hot air heating or ultrasonic welding. Through the above steps, high-performance fiber raw materials such as theanine lyocell fiber, PCM viscose fiber and antibacterial and mildew-proof cotton fiber are successfully combined with combing, melt-bonding and other processes to prepare a composite flake product with excellent warmth retention, antibacterial and mildew-proof properties and air permeability.

[0051] The performance test of the composite flakes with air interlayer prepared by the present invention is as follows:

[0052] Test method: The antibacterial property is tested according to GB / T 20944.3-2008 "Evaluation of antibacterial properties of textiles Part 3: Oscillation method". The mildew resistance is tested according to AATCC 30-2012 "Test method for mildew resistance of textiles". The warmth retention is tested according to GB / T 11048-2018 "Determination of thermal resistance and moisture resistance under steady-state conditions of physiological comfort of textiles (evaporative hot plate method)". The breathability is tested according to GB / T5453-1997 "Determination of breathability of textile fabrics".

[0053] Test results:

[0054]

[0055] The foregoing has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and what is described in the above embodiments and the specification is only to illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will also have various changes and improvements, and these changes and improvements fall within the scope of the present invention as claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. Preparation method of antibacterial and mildew-proof agent for textile, characterized in that, It includes the following steps: Step 1: After mixing the theanine powder evenly with the loading material, add absolute ethanol to fully soak it, then heat and reflux for 24 h - 48 h, and then evaporate the solvent to obtain the supported antibacterial material; Step 2: After grinding and crushing the supported antibacterial material, heat it to 200 °C - 230 °C for the first time and keep it warm for 2 h - 4 h, then heat it to 380 °C - 400 °C for the second time and keep it warm for 5 h - 8 h to obtain the preliminary product of the antibacterial and mildew-proof agent; Step 3: Mix the preliminary product of the antibacterial and mildew-proof agent, nano-zinc oxide powder, IPBC, and binder evenly to obtain a mixture; Step 4: Put the mixture and silica sol into a ball mill and ball mill for 5 h - 8 h to obtain a ball-milled mixture; Step 5: Mix the ball-milled mixture with an aqueous solution of polyvinyl alcohol, mechanically stir at a speed of 500 r / min - 1000 r / min for 20 min - 30 min, then add a cross-linking agent, mechanically stir at a speed of 1200 r / min - 1500 r / min for 15 min - 30 min, then add an antifoaming agent, and mechanically stir evenly for 8 min - 10 min. After removing the air in the mixture under negative pressure, obtain the injection molding material; Step 6: Inject the injection molding material into a mold and dry it at 90 °C - 100 °C to cure the injection molding material into a block; then, transfer it to an electric resistance furnace, heat it to 300 °C - 320 °C in a nitrogen atmosphere and sinter for 4 h - 5 h; then, after cooling to room temperature, take it out and grind and crush it to obtain the antibacterial and mildew-proof agent for textiles.

2. The preparation method of the antibacterial and mildew-proof agent for textiles according to claim 1, wherein In Step 1, the loading material is diatomite powder with a particle size of 10 μm - 20 μm.

3. The preparation method of the antibacterial and mildew-proof agent for textiles according to claim 2, characterized in that, In Step 5, the aqueous solution of polyvinyl alcohol is an aqueous solution of polyvinyl alcohol with a mass concentration of 10%.

4. The preparation method of the antibacterial and mildew-proof agent for textiles according to claim 3, characterized in that, In Step 1, the mass ratio of the theanine powder to the diatomite powder is 1 - 3:1, and the absolute ethanol accounts for 10% - 30% of the total mass; In Step 3, the mass ratio of the preliminary product of the antibacterial and mildew-proof agent, nano-zinc oxide powder, IPBC, and binder is 5:1 - 2:2 - 1:2; In Step 4, the mass ratio of the mixture to the silica sol is 2:3; In Step 5, the aqueous solution of polyvinyl alcohol with a mass concentration of 10% accounts for 5% - 10% of the total mass; the cross-linking agent accounts for 1% of the total mass, and the antifoaming agent accounts for 0.1% - 0.5% of the total mass.

5. Preparation method of antibacterial and mildew-proof cotton fiber, characterized in that, The antibacterial and mildew-proof agent for textiles prepared by the preparation method of the antibacterial and mildew-proof agent for textiles according to any one of claims 1 - 4; add the antibacterial and mildew-proof agent for textiles to the lint fiber to obtain the antibacterial and mildew-proof cotton fiber.

6. The preparation method of the antibacterial and mildew-proof cotton fiber according to claim 5, characterized in that, It includes the following steps: Step a: Immerse the lint fiber in an aqueous solution containing cellulase, hemicellulase, and pectinase, and perform oscillation treatment. At the same time, heat it to 45 °C at a heating rate of 5 °C / min and keep it warm for 3 h - 4 h; Step b: Rinse the lint fiber treated in Step a with hot water at 40 °C - 50 °C. Step c, adding acid and water to the rinsed lint cotton fiber, adjusting the pH value to 5.5-7.5, adding an aqueous solution containing 5g / L-8g / L of an antibacterial and mildew-proof agent for textile use, controlling the bath ratio at 1:6, shaking and impregnating for 15min-20min, and then dehydrating to obtain antibacterial and mildew-proof cotton fiber.

7. The preparation method of the antibacterial and mildew-proof cotton fiber according to claim 6, wherein, In step a, the weight of cellulase is 1%-3% of the weight of the lint fiber, the weight of hemicellulase is 1%-3% of the weight of the lint fiber, and the weight of pectinase is 1%-2% of the weight of the lint fiber.

8. The preparation method of the antibacterial and mildew-proof cotton fiber according to claim 6, wherein A refining agent is also added to the aqueous solution in step a, and the refining agent is one or more of sodium dodecylbenzene sulfonate, sodium secondary alkyl sulfonate, nonylphenol polyoxyethylene ether, and isomeric alcohol ether carboxylates.

9. A method for preparing an antibacterial and mildew-proof cotton wadding sheet, characterized in that, The method comprises the following steps: performing a loosening and combing process on the antibacterial and mildew-proof cotton fibers to obtain antibacterial and mildew-proof cotton flakes.

10. A method for preparing a composite flake with an air interlayer, characterized in that, The method comprises the following steps: ① the antibacterial and mildew-proof cotton fiber, theanine lyocell fiber, PCM viscose fiber and low melting point fiber are respectively subjected to preliminary opening by a wool blending machine, and then subjected to fine opening treatment until the fibers are broken into a loose state; Step ②, the antibacterial and mildew-proof cotton fiber, theanine lyocell fiber and low-melting-point fiber treated in step ① are put into a mixer and fully mixed to obtain an upper layer material; at the same time, the PCM viscose fiber and the antibacterial and mildew-proof cotton fiber treated in step ① are put into a mixer and fully mixed to obtain a lower layer material; Step ③, use a carding machine to card the upper layer of material, and then cross-lay the fiber web with α as the laying angle to form an upper layer of flakes; at the same time, use a carding machine to card the lower layer of material, and then continuously fold, pile and lay the fiber web to form a lower layer of flakes; Step ④: Place the upper flake layer on the lower flake layer, and then melt-bond the two layers of fiber web at the contact surface to obtain a composite flake with an air interlayer.

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