A method for preparing odor-removing sanitary napkins

Abstract

This invention discloses a method for preparing odor-removing sanitary napkins. The invention comprises a surface layer, a core layer, and a bottom membrane. The surface layer consists of an antibacterial and deodorizing layer and an anti-backflow layer. The core layer is composed of AB60SX deodorizing SAP and OC deodorizing wood pulp, wherein the ratio of deodorizing SAP to deodorizing wood pulp is 1:5-2:5. The bottom membrane is a deodorizing and breathable membrane, which is made of: 50-75 parts base material; 10-25 parts breathable filler; 5-15 parts β-cyclodextrin; and 0.5-2 parts crosslinking agent. This invention designs an antibacterial and deodorizing surface layer combined with an antibacterial core and a deodorizing and breathable bottom membrane. The surface layer uses a highly biosafe, all-plant-based antibacterial oil agent to inhibit the growth and reproduction of microorganisms, thus preventing the generation of odor sources. The bottom membrane is made by casting and stretching a special deodorizing inorganic breathable material. When odor molecules pass through the breathable pores of the bottom membrane, they are captured. The internal antibacterial core inhibits odor sources, and the bottom and surface layers absorb the emitted odors, thereby achieving long-term prevention of odor generation.

Description

Technical Field

[0001] This invention relates to a method for preparing an odor-removing sanitary napkin. Background Technology

[0002] Sanitary napkins are hygiene products designed for women during menstruation. Because menstrual blood has a distinctive odor, especially for middle-aged and older women or those with gynecological conditions, the odor is particularly strong. Therefore, in addition to basic absorbency, some women also need to eliminate the odor. Currently, deodorizing sanitary napkins on the market mainly rely on fragrance molecules to mask the odor and on antibacterial and bacteriostatic ingredients in the contact layer. Masking the odor with fragrance molecules is only a temporary solution; the safety of the fragrance and the pleasantness of the mixed scent are often insufficient to satisfy most consumers. Furthermore, traditional cationic bactericides used in sanitary napkins can cause a hemolytic effect with menstrual blood, resulting in a darkening appearance. Additionally, the hydrophilic oil agents in the surface layer are mostly anionic / nonionic systems, leading to compatibility issues. Moreover, traditional cationic bactericides have low biocompatibility, causing damage to the skin and mucous membranes when used in the surface layer. Moreover, this method of deodorization has a short duration, generally around 8-12 hours. After a longer period, an odor will be emitted, which can affect the surrounding air quality when disposed of in indoor trash cans. Summary of the Invention

[0003] To overcome the above-mentioned defects, the purpose of this invention is to provide a method for preparing an odor-removing sanitary napkin with an odor-removing time of more than 72 hours.

[0004] To achieve the above objectives, the present invention provides a method for preparing an odor-removing sanitary napkin, wherein the sanitary napkin comprises a surface layer, a core layer, and a bottom film; wherein,

[0005] The surface layer consists of an antibacterial and deodorizing layer and an anti-backflow layer; wherein, the antibacterial and deodorizing layer is made of ES fiber treated with plant antibacterial oil and polypropylene deodorizing fiber bonded together by hot air; wherein, the plant antibacterial oil comprises the following raw materials in parts by weight: wetting agent 15-30 parts; penetrant 15-25 parts; emulsifier 10-15 parts; plant antibacterial agent VLC 2-8 parts; cosolvent 5-15 parts;

[0006] The polypropylene deodorizing fiber is prepared by the following method: Preparation of acid-washed activated carbon containing plant antibacterial agent: The plant antibacterial agent and 30 mg of propylene glycol are mixed and dispersed in 15 ml of deionized water with ultrasonic assistance. Then, 135 mg of acid-washed activated carbon with a particle size of 0.025-0.050 mm is stirred and reacted at 60 °C overnight. After the reaction stops, the mixture is filtered to remove unreacted propylene glycol and plant antibacterial agent. The filtrate is placed in a dialysis bag with a molar mass of 1000 and the dialysis bag is immersed in water for dialysis for 5 h. Finally, the retained solution is placed in an Erlenmeyer flask and freeze-dried for 24 h to obtain the inclusion product.

[0007] Preparation of polypropylene deodorizing fiber: 0.5-5 parts of silane and 72-85 parts of acid-washed activated carbon combined with plant antibacterial agent are thoroughly mixed, and then 15-20 parts of anhydrous ethanol are added and stirred for 30 minutes to form mixture A. This mixture is poured into the raw material tank of a plasma vacuum coating machine, and plasma chemical vapor deposition is performed on the polypropylene fiber. The argon flow rate is set to 100 ml / min, the radio frequency power is 240 W, the radio frequency mode is continuous wave, the vacuum degree is 9 Pa, the raw material evaporation temperature is 100℃, and the feed flow rate is 0.02-0.06 ml / min to obtain deodorizing fiber.

[0008] The core layer is composed of AB60SX deodorizing SAP and OC deodorizing wood pulp, wherein the ratio of deodorizing SAP to deodorizing wood pulp is 1:5-2:5;

[0009] The bottom membrane is an odor-absorbing and breathable bottom membrane, which is made of base material: 50-75 parts; breathable filler: 10-2 parts; β-cyclodextrin: 5-15 parts; crosslinking agent: 0.5-2 parts;

[0010] Furthermore, the method for preparing the plant-based antibacterial oil includes the following steps:

[0011] Weigh the plant antibacterial agent into the reaction vessel and stir at room temperature for 30 minutes before use;

[0012] Weigh the wetting agent and penetrant into the reaction vessel, heat to 65°C, and stir rapidly for 20 minutes;

[0013] Weigh out the emulsifier and cosolvent, add them to the reaction vessel under stirring, and start cooling after stirring for 15 minutes.

[0014] After the temperature drops to 45℃, slowly pour in the prepared plant antibacterial agent and synergist, and continue stirring for 30 minutes to obtain the final product.

[0015] Furthermore, the plant-based antibacterial oil agent comprises the following raw materials in parts by weight: it also includes 2-15 parts of other synergistic adjuvants.

[0016] Furthermore, the wetting agent is one or a combination of the following raw materials: alkyl alcohol polyoxyethylene ether, polyethylene glycol laurate, isomeric alcohol polyether, and polyether silicone oil;

[0017] The penetrant is one or a combination of the following raw materials: dioctyl sulfonate salt, potassium phosphate salt;

[0018] The emulsifier is one or a combination of the following raw materials: polyoxyethylene dehydrated sorbitan monooleate, dehydrated sorbitan monooleate.

[0019] Furthermore, the masterbatch for the deodorizing and breathable bottom membrane is made using the following method:

[0020] The air-permeable filler and β-cyclodextrin were pulverized to the specified particle size and then mixed evenly.

[0021] Add 5% glycerol and mix quickly and thoroughly again before use;

[0022] The base material, the mixed deodorizing and breathable filler, the crosslinking agent, and other additives are added to a high-efficiency mixer in sequence. After mixing evenly, the mixture is placed in the feeding port of a twin-screw extruder. The temperature is set to 150-165℃, and the mixture is extruded, sliced, and granulated to obtain the final product.

[0023] Furthermore, the method for preparing the plant-based antibacterial oil includes the following steps:

[0024] Weigh the plant antibacterial agent VLC into a reaction vessel and stir at room temperature for 30 minutes before use.

[0025] Weigh the wetting agent and penetrant into the reaction vessel, heat to 65°C, and stir rapidly for 20 minutes;

[0026] Weigh out the emulsifier and cosolvent, add them to the reaction vessel under stirring, and start cooling after stirring for 15 minutes.

[0027] After the temperature drops to 45℃, slowly pour in the prepared plant antibacterial agent and synergist, and continue stirring for 30 minutes to obtain the final product.

[0028] Furthermore, the particle size of the breathable filler is 0.5-1 mm, and the particle size of the β-cyclodextrin is 0.1-0.3 mm.

[0029] Furthermore, the anti-backflow layer is a hot-air nonwoven fabric.

[0030] This invention treats the surface layer of ES fibers with the highly biosafe plant-based antibacterial agent VLC, inhibiting the growth and reproduction of microorganisms and preventing further odor generation. It also solves the problem of traditional cationic bactericides causing hemolysis upon contact with menstrual blood, leading to a darkening of the surface. Furthermore, it uses acid-washed activated carbon to prepare deodorizing fibers, which adsorb odors and have bactericidal effects, effectively preventing odors from emanating from the surface layer. The acid-washed activated carbon has a larger specific surface area, enabling it to adsorb odor molecules without participating in absorption during liquid penetration into the fibers, and it does not affect the fiber's softness.

[0031] Using AB60SX deodorizing SAP and OC deodorizing wood pulp, which have good deodorizing and absorption functions, as the core layer, it effectively prevents the menstrual blood absorbed by the core from producing odors and achieves internal inhibition of odor sources.

[0032] The bottom membrane is made of a special deodorizing inorganic breathable material that is cast and stretched. When odor molecules pass through the breathable holes of the bottom membrane, they are captured, achieving the dual function of internally inhibiting odor sources and bottomly adsorbing and releasing malodors.

[0033] Overall, this invention can largely prevent the occurrence of odors through antibacterial treatment of the surface layer and core layer; and by using effective odor adsorption treatment in both the surface layer and bottom film layer, it can prevent the emission of odors to the maximum extent, thereby preventing the generation and emission of odors in the sanitary napkin as a whole, and thus passing the test for more than 72 hours. Detailed Implementation

[0034] The embodiments of the present invention will now be described in detail.

[0035] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the indicated orientation or positional relationship, and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0036] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0037] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0038] The present invention aims to provide a method for preparing odor-removing sanitary napkins. The present invention achieves an odor-removing effect of more than 72 hours by subjecting the sanitary napkin, including the surface layer, core layer and bottom film, to antibacterial or deodorizing treatment.

[0039] The surface layer consists of an antibacterial and deodorizing layer and an anti-backflow layer. The antibacterial and deodorizing layer is made of ES fiber treated with plant antibacterial oil and polypropylene deodorizing fiber bonded together by hot air. The anti-backflow layer is ordinary hot air non-woven fabric. Adding the anti-backflow layer can better prevent menstrual blood from backflowing and affecting the ability of polypropylene deodorizing fiber to absorb odors.

[0040] The plant-based antibacterial oil agent comprises the following raw materials in parts by weight:

[0041] Wetting agent 15-30 parts; penetrant 15-25 parts; emulsifier 10-15 parts; plant antibacterial agent VLC 2-8 parts;

[0042] 5-15 parts of co-solvent;

[0043] VLC, a plant-based antibacterial agent, is produced by Guangzhou Aizhuo Biotechnology Co., Ltd. VLC antibacterial agent.

[0044] The polypropylene deodorizing fiber is prepared by the following method: Preparation of acid-washed activated carbon containing plant antibacterial agent: The plant antibacterial agent and 30 mg of propylene glycol are mixed and dispersed in 15 ml of deionized water with ultrasonic assistance. Then, 13 mg of acid-washed activated carbon is added and stirred at 60 °C overnight. After the reaction stops, the mixture is filtered to remove unreacted propylene glycol and plant antibacterial agent. The filtrate is placed in a dialysis bag with a molar mass of 1000 and the dialysis bag is immersed in water for dialysis for 5 h. Finally, the retained solution is placed in an Erlenmeyer flask and freeze-dried for 24 h to obtain the inclusion product.

[0045] Preparation of polypropylene deodorizing fiber: 0.5-5 parts of silane and 72-85 parts of acid-washed activated carbon combined with plant antibacterial agent are thoroughly mixed, and then 15-20 parts of anhydrous ethanol are added and stirred for 30 minutes to form mixture A. This mixture is poured into the raw material tank of a plasma vacuum coating machine, and plasma chemical vapor deposition is performed on the polypropylene fiber. The argon flow rate is set to 100 ml / min, the radio frequency power is 240 W, the radio frequency mode is continuous wave, the vacuum degree is 9 Pa, the raw material evaporation temperature is 100℃, and the feed flow rate is 0.02-0.06 ml / min to obtain deodorizing fiber.

[0046] The surface deodorizing non-woven fabric is made of the above-mentioned antibacterial ES fiber and the above-mentioned polypropylene deodorizing fiber bonded together by hot air, with an addition ratio of 2:1. The ES fiber is the outer layer component, which is polyethylene and has a low melting point, serving as a hot adhesive. Polypropylene is the main skeleton component. The preparation temperature is 110℃-115℃, the melting point of polyethylene. The two types of fibers are arranged alternately in a honeycomb pattern to fully exert the antibacterial and deodorizing efficiency.

[0047] The core layer is composed of Sumitomo Seika's AB60SX deodorized SAP and International Paper's OC deodorized wood pulp, wherein the ratio of deodorized SAP to deodorized wood pulp is 1:5 to 2:5 of AB60SX; for example, 0.5g of AB60SX SAP and 2.5g of IP OC wood pulp.

[0048] The bottom membrane is an odor-removing and breathable bottom membrane, which is made of base material: 50-75 parts; breathable filler: 10-2 parts; β-cyclodextrin: 5-15 parts; crosslinking agent: 0.5-2 parts.

[0049] The above-mentioned plant antibacterial oil is composed of plant antibacterial agents and multi-lipophilic agents. The plant antibacterial agent accounts for 2-8% of the mass, which has a good antibacterial effect and does not affect the hydrophilic properties of the oil. The multi-lipophilic agent is selected from oil types with strong fiber adhesion, which can effectively improve the antibacterial efficiency.

[0050] This oil acts on the outer layer of ES fibers, primarily composed of PE material. PE has an interfacial tension of approximately 27-36 mN / m, exhibiting superhydrophobic interfacial properties. Therefore, both the antibacterial agent and the oil require superior wettability and film-forming ability at the interface. Increasing the EO number increases the HLB value of the oil, coating it with hydrophobic groups, which reduces the adsorption capacity of the antibacterial agent on PE, making it difficult to form an antibacterial hydrophilic film. Conversely, decreasing the EO number reduces surface tension, resulting in an excessively large droplet contact angle and poor wettability. Furthermore, excessively short alkyl chains affect the dispersibility of the antibacterial agent in the formulation, while excessively long chains increase hydrophobicity, leading to decreased wettability. Therefore, the required alkyl chain length after mixing is between 10-13, the EO number is between 5-8, and the HLB value after emulsification of the plant-based antibacterial agent and the base oil is between 10-13.

[0051] This plant-based antibacterial agent has high compatibility with oil-based formulations. The following basic oil-based formulations include, but are not limited to, the specific names mentioned. Specific solutions are as follows:

[0052] ES fiber hot air plant antibacterial oil agent (parts by weight): Wetting agent (15-30 parts): alkyl alcohol polyoxyethylene ether, polyethylene glycol laurate, isomeric alcohol polyether, polyether silicone oil, etc.; Penetrant (15-25 parts): sulfonated dioctyl succinate, potassium phosphate, etc.; Emulsifier (10-15 parts): polyoxyethylene dehydrated sorbitan monooleate, dehydrated sorbitan monooleate, etc.; Plant antibacterial agent VLC (2-8 parts); Cosolvent (5-15 parts): propylene glycol, butanediol, 1,2-ethylene glycol, etc.; Other synergistic additives (2-15 parts): amino acid derivatives, ethylhexylglycerin, etc. Production process: Weigh the raw materials of the plant antibacterial agent into a reaction vessel and stir at room temperature for 30 minutes. Separately weigh the raw materials of the wetting agent and penetrant into the reaction vessel, heat to 65°C and stir rapidly for 20 minutes. Weigh the raw materials of the emulsifier and cosolvent and add them under stirring. After stirring for 15 minutes, start cooling. After the temperature drops to 45°C, slowly pour in the prepared plant antibacterial agent and synergistic adjuvant, and continue stirring for 30 minutes to obtain the final product.

[0053] Specific examples (parts by weight): 20 parts alkyl alcohol polyoxyethylene ether, 16 parts polyethylene glycol laurate, 15 parts isomeric alcohol polyether, 13 parts sulfonated dioctyl succinate, 10 parts polyoxyethylene dehydrated sorbitan monooleate, 8 parts propylene glycol, 3 parts glyceryl caprylate, and 8 parts plant antibacterial agent VLC.

[0054] The aforementioned deodorizing and breathable bottom membrane is formed by mixing calcium carbonate and breathable filler, followed by casting and stretching to create micropores. This invention combines the deodorizing agent and breathable filler with a crosslinking agent. The appropriate ratio of these components can save costs and increase deodorizing efficiency. The particle size of the breathable filler is directly related to the pore diameter; therefore, preferably, the calcium carbonate particle size is between 0.5-1 mm, and the deodorizing agent particle size is between 0.1-0.3 mm. The specific solution is as follows:

[0055] The deodorizing and breathable bottom membrane is made from the following raw materials in parts by weight:

[0056] Base material: 50-75 parts by weight, made of polyethylene + polyolefin elastomer;

[0057] Breathable filler: 10-25 parts by weight, made of calcium carbonate and titanium dioxide;

[0058] Odor remover: 5-15 parts by weight, using cucurbitacin, cyclodextrin, activated carbon, etc.;

[0059] Crosslinking agent: 0.5-2 parts by weight; titanium ester or aluminate ester are used.

[0060] Other additives: 0.5-2 parts by weight; pentaerythritol tetrakis[propionic acid], tris[2,4-di-tert-butylphenyl] phosphite, etc.

[0061] Process: After the breathable filler and deodorizing agent are crushed to the specified particle size, they are mixed evenly. 5% glycerol is added and mixed quickly and evenly again. The base material, the mixed deodorizing and breathable filler, crosslinking agent, and other additives are added to a high-speed mixer in sequence. After mixing evenly, the mixture is placed in the feeding port of a twin-screw extruder. The temperature is set to 150-165℃, and the mixture is extruded, sliced, and granulated to obtain the final product.

[0062] Specific example (mass fraction): Polyethylene 58%, Polyolefin elastomer 12%, Calcium carbonate 12%, Titanium dioxide 5%, Cucurbita 8%, Titanate 1%, Pentaerythritol tetrakis[propionate] 0.6%, Tris[2,4-di-tert-butylphenyl] phosphite 0.3%.

[0063] The test results of the deodorizing ability of the sanitary napkin described in this invention were presented, and compared with the deodorizing ability results of commercially available deodorizing sanitary napkins. The following table shows the results using 20 μL of menstrual blood as the odor source:

[0064] Test results:

[0065]

[0066] In summary, this invention, through its antibacterial and deodorizing surface layer, deodorizing core, and compounded deodorizing and breathable bottom film, can achieve a deodorizing effect of over 72 hours. This meets the needs of special personnel, such as astronauts, security guards on long-term duty, and workers involved in earthquake relief efforts.

[0067] The present invention has been described in detail above, but it is not limited to the embodiments described above. Various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the invention. Many other changes and modifications made without departing from the concept and scope of the invention should be considered within the scope of protection of the present invention.

[0068] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0069] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing an odor-removing sanitary napkin, characterized in that, The sanitary napkin comprises a surface layer, a core layer, and a bottom film; wherein, The surface layer comprises an antibacterial and deodorizing layer and an anti-backflow layer; wherein the antibacterial and deodorizing layer is made of ES fibers treated with plant antibacterial oil and polypropylene deodorizing fibers bonded together by hot air; wherein the plant antibacterial oil comprises the following raw materials in parts by weight: Wetting agent 15-30 parts; penetrant 15-25 parts; emulsifier 10-15 parts; plant antibacterial agent VLC 2-8 parts; 5-15 parts of co-solvent; The polypropylene deodorizing fiber is prepared by the following method: Preparation of acid-washed activated carbon containing plant antibacterial agent: The plant antibacterial agent and 30 mg of propylene glycol are mixed and dispersed in 15 ml of deionized water with ultrasonic assistance. Then, 135 mg of acid-washed activated carbon with a particle size of 0.025-0.050 mm is stirred and reacted at 60 °C overnight. After the reaction stops, the mixture is filtered to remove unreacted propylene glycol and plant antibacterial agent. The filtrate is placed in a dialysis bag with a molar mass of 1000 and the dialysis bag is immersed in water for dialysis for 5 h. Finally, the retained solution is placed in an Erlenmeyer flask and freeze-dried for 24 h to obtain the inclusion product. Preparation of polypropylene deodorizing fiber: 0.5-5 parts of silane and 72-85 parts of acid-washed activated carbon combined with plant antibacterial agent are thoroughly mixed, and then 15-20 parts of anhydrous ethanol are added and stirred for 30 minutes to form mixture A. This mixture is poured into the raw material tank of a plasma vacuum coating machine, and plasma chemical vapor deposition is performed on the polypropylene fiber. The argon flow rate is set to 100 ml / min, the radio frequency power is 240 W, the radio frequency mode is continuous wave, the vacuum degree is 9 Pa, the raw material evaporation temperature is 100℃, and the feed flow rate is 0.02-0.06 ml / min to obtain deodorizing fiber. The core layer is composed of AB60SX deodorizing SAP and OC deodorizing wood pulp, wherein the ratio of deodorizing SAP to deodorizing wood pulp is 1:5-2:5; The bottom membrane is a deodorizing and breathable bottom membrane, which is made of base material: 50-75 parts; breathable filler: 10-25 parts; β-cyclodextrin: 5-15 parts; crosslinking agent: 0.5-2 parts.

2. The method for preparing the deodorizing sanitary napkin as described in claim 1, characterized in that, The method for preparing the plant-based antibacterial oil includes the following steps: Weigh the plant antibacterial agent into the reaction vessel and stir at room temperature for 30 minutes before use; Weigh the wetting agent and penetrant into the reaction vessel, heat to 65°C, and stir rapidly for 20 minutes; Weigh out the emulsifier and cosolvent, add them to the reaction vessel under stirring, and start cooling after stirring for 15 minutes. After the temperature drops to 45℃, slowly pour in the prepared plant antibacterial agent and synergist, and continue stirring for 30 minutes to obtain the final product.

3. The method for preparing the deodorizing sanitary napkin as described in claim 1, characterized in that, The wetting agent is one or a combination of the following raw materials: alkyl alcohol polyoxyethylene ether, polyethylene glycol laurate, isomeric alcohol polyether, and polyether silicone oil; The penetrant is one or a combination of the following raw materials: dioctyl sulfonate salt, potassium phosphate salt; The emulsifier is one or a combination of the following raw materials: polyoxyethylene dehydrated sorbitan monooleate, dehydrated sorbitan monooleate.

4. The method for preparing the deodorizing sanitary napkin as described in claim 1, characterized in that, The masterbatch for the deodorizing and breathable bottom membrane is made using the following method: The air-permeable filler and β-cyclodextrin were pulverized to the specified particle size and then mixed evenly. Add 5% glycerol and mix quickly and thoroughly again before use; The base material, the mixed deodorizing and breathable filler, the crosslinking agent, and other additives are added to a high-efficiency mixer in sequence. After mixing evenly, the mixture is placed in the feeding port of a twin-screw extruder. The temperature is set to 150-165℃, and the mixture is extruded, sliced, and granulated to obtain the final product.

5. The method for preparing the deodorizing sanitary napkin as described in claim 1, characterized in that, The air-permeable filler has a particle size of 0.5-1 mm, and the β-cyclodextrin has a particle size of 0.1-0.3 mm.

6. The method for preparing the deodorizing sanitary napkin as described in claim 1, characterized in that, The backflow prevention layer is made of hot air nonwoven fabric.

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