Nonwoven fabric for atomizing core and its preparation method

Abstract

This application discloses a nonwoven fabric for an atomizing core and its preparation method. The nonwoven fabric for the atomizing core includes a lower fiber layer, a middle fiber layer, and an upper fiber layer stacked together. The upper fiber layer comprises, by weight, 30-40 parts of a first polyimide fiber and 60-70 parts of pure cotton fiber. The middle fiber layer comprises, by weight, 10-50 parts of a second polyimide fiber, 20-40 parts of pure cotton fiber, and 30-50 parts of viscose fiber. The lower fiber layer comprises, by weight, 100 parts of viscose fiber. The fineness of the first polyimide fiber is greater than that of the second polyimide fiber. The beneficial effect of this application is that it provides a nonwoven fabric for an atomizing core that combines heat resistance and oil-wicking properties, and its preparation method.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of atomization cores, in particular to a non-woven fabric for an atomization core and a preparation method thereof. BACKGROUND

[0002] One of the core components of an electronic atomization device is an atomization core, which generally includes two parts of a liquid guiding element and a heating element; wherein the liquid guiding element is used to guide the liquid aerosol substrate; the heating element is used to heat and atomize the liquid aerosol substrate to form an aerosol when powered. Currently, there are two types of oil guiding cotton used in atomization cores: one is a cotton core material represented by cellulose fiber, and the other is porous oil guiding ceramic. Although the porous oil guiding ceramic has excellent heat resistance, its liquid guiding rate is limited, and its application range is small and its cost is high. Therefore, cotton core is still the mainstream liquid guiding material for atomization cores.

[0003] The cotton core material is mainly a non-woven fabric obtained by a hydroentangling process using natural cotton fiber, natural hemp fiber, viscose fiber and other cellulose fiber materials. In actual use, these cellulose fibers will gradually hydrolyze and degrade under wet and hot conditions. With the extension of the atomization time, the cellulose fibers will gradually carbonize, and carbon will be produced on the heating element, resulting in a worse taste of the atomization core and eventually a burnt core. Therefore, the service life of the atomization core with traditional cotton core material is short, and it needs to be replaced frequently. These drawbacks greatly limit the development of electronic atomization devices.

[0004] In order to increase the heat resistance of the oil guiding cotton of the atomization core and prolong the service life of the atomization core, the heat resistance of the oil guiding cotton can be improved by adding heat-resistant fiber materials. However, if only heat-resistant materials are simply and directly added, the oil guiding ability of the oil guiding cotton will be severely weakened, and insufficient oil guiding ability will cause dry burning and burnt core problems. In this case, the service life of the atomization core is even shorter.

[0005] There is currently no cotton core solution to solve the above problems. SUMMARY

[0006] Therefore, the present application provides a non-woven fabric for an atomization core and a preparation method thereof, aiming to improve the problem that the existing cotton core material cannot balance heat resistance and oil guiding performance.

[0007] The present application is implemented in the following manner. A non-woven fabric for an atomization core includes a lower fiber layer, a middle fiber layer and an upper fiber layer stacked together.

[0008] The upper fiber layer includes the following components by mass fraction: 30-40 parts of first polyimide fiber, and 60-70 parts of pure cotton fiber.

[0009] The middle fiber layer includes the following components by mass fraction: 10-50 parts of second polyimide fiber, 20-40 parts of pure cotton fiber, and 30-50 parts of viscose fiber.

[0010] The lower fiber layer comprises the following components by mass fraction: viscose fiber 100 parts;

[0011] The fineness of the first polyimide fiber is greater than the fineness of the second polyimide fiber.

[0012] Optionally, in some embodiments of the present application, the first polyimide fiber is a thick denier polyimide fiber, and the second polyimide fiber is a fine denier polyimide fiber.

[0013] And / or the first polyimide fiber is a shaped cross-section polyimide fiber, and the second polyimide fiber is a shaped cross-section polyimide fiber.

[0014] Optionally, in some embodiments of the present application, the first polyimide fiber is obtained by surface modification treatment of a first fiber raw material, and / or the second polyimide fiber is obtained by surface modification treatment of a second fiber raw material.

[0015] Wherein, the first fiber raw material is a thick denier polyimide fiber, and the second fiber raw material is a fine denier polyimide fiber.

[0016] And / or the first fiber raw material is a shaped cross-section polyimide fiber, and the second fiber raw material is a shaped cross-section polyimide fiber.

[0017] Optionally, in some embodiments of the present application, the viscose fiber is a fine denier viscose fiber.

[0018] Optionally, in some embodiments of the present application, the length of the first polyimide fiber ranges from 38-60mm, and the fineness of the first polyimide fiber ranges from 2.2-6.0dtex.

[0019] The length of the second polyimide fiber ranges from 38-60mm, and the fineness of the second polyimide fiber ranges from 0.9-1.3dtex.

[0020] The length of the viscose fiber ranges from 18-60mm, and the fineness of the viscose fiber ranges from 0.5-3.8dtex.

[0021] The length of the pure cotton fiber ranges from 18-38mm, and the fineness of the pure cotton fiber ranges from 0.5-3.8dtex.

[0022] Optionally, in some embodiments of the present application, the thickness ratio of the upper fiber layer ranges from 40%-50%, the thickness ratio of the middle fiber layer ranges from 25%-30%, and the thickness ratio of the lower fiber layer ranges from 25%-30%, based on the overall thickness of the non-woven fabric.

[0023] Optionally, in some embodiments of the present application, the upper fiber layer accounts for 20-40% of the total mass of the non-woven fabric, the middle fiber layer accounts for 20-40% of the total mass of the non-woven fabric, and the lower fiber layer accounts for 20-40% of the total mass of the non-woven fabric.

[0024] The porosity of the upper fiber layer is 85-95%, the porosity of the middle fiber layer is 80-90%, and the porosity of the lower fiber layer is 75-85%.

[0025] Optionally, in some embodiments of the present application, the total mass of the non-woven fabric for the atomizing core is 60-150 g / m 2 , and the total thickness of the non-woven fabric for the atomizing core is 0.4-1.2 mm.

[0026] Correspondingly, the present application also provides a preparation method of the above-mentioned non-woven fabric for the atomizing core, comprising the following steps:

[0027] Mix the first polyimide fiber and the pure cotton fiber according to a proportion, and perform carding and web laying to obtain an upper uniform fiber web;

[0028] Mix the second polyimide fiber, the pure cotton fiber and the viscose fiber according to a proportion, and perform carding and web laying to obtain a middle uniform fiber web;

[0029] Card and lay the viscose fiber to obtain a lower uniform fiber web;

[0030] Perform reinforcement treatment on the whole of the upper uniform fiber web, the middle uniform fiber web and the lower uniform fiber web to obtain the non-woven fabric for the atomizing core.

[0031] Optionally, in some embodiments of the present application, the reinforcement treatment on the whole of the upper uniform fiber web, the middle uniform fiber web and the lower uniform fiber web comprises the following steps:

[0032] Place the upper uniform fiber web, the middle uniform fiber web and the lower uniform fiber web in order from top to bottom, and complete preliminary compounding by hot rolling to obtain a three-layer fiber web composite material;

[0033] Perform pre-punching treatment on the three-layer fiber web composite material;

[0034] Perform multi-pass forward and reverse hydroentanglement on the three-layer fiber web composite material after the pre-punching treatment, and dry the three-layer fiber web composite material to obtain the non-woven fabric;

[0035] The pre-piercing water pressure of the pre-piercing treatment is 1-10 bar, the water jet pressure of the multi-pass forward and reverse water jet is 20-50 bar, the water jet pressure of the multi-pass forward and reverse water jet is gradually increased, the jet time of the water jet pressure of the forward and reverse water jet is 0.5-15 min, and the linear speed of the forward and reverse water jet is 30-100 m / min.

[0036] The application has the beneficial effect of providing a non-woven fabric for an atomizing core with heat resistance and oil guiding performance and a preparation method thereof.

[0037] More specifically, some embodiments of the application can produce the following specific beneficial effects: through the laminated arrangement of the lower fiber layer, the middle fiber layer and the upper fiber layer, the upper fiber layer is blended with first polyamide-imide fibers and pure cotton fibers, the middle fiber layer is blended with second polyamide fibers, pure cotton fibers and viscose fibers, and the lower layer is viscose fiber, and since the fineness of the first polyamide fiber is greater than that of the second polyamide fiber, the heat resistance of the first polyamide fiber is better than that of the second polyamide fiber. Based on the material collocation of each layer, the heat resistance of the non-woven fabric gradually decreases from the upper fiber layer to the lower fiber layer, and the oil guiding performance gradually increases from the upper fiber layer to the lower fiber layer, so that the non-woven fabric of the application has excellent heat resistance and oil guiding performance, avoids weakening the oil guiding performance of the non-woven fabric after adding polyamide fibers, and can prolong the service life of the atomizing core when applied to the atomizing core. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0039] Figure 1 is a main step schematic block diagram of a preparation method of a non-woven fabric for an atomizing core provided by the application. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the application will be described clearly and completely with reference to the drawings of the embodiments of the application. Obviously, the described embodiments are only some embodiments of the application, not all embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application. In addition, it should be understood that the specific embodiments described herein are only used to illustrate and explain the application, and are not used to limit the application.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application. As used in this description, the singular forms "a", "an", and "the" include plural references unless the context clearly dictates otherwise. The term "and / or" includes any and all combinations of one or more of the associated listed items.

[0042] In the present application, the orientation words such as "upper" and "lower" are used in the actual use or working state of the device, and the specific direction of the drawing surface in the drawing is referred to as "upper" and "lower"; and "inner" and "outer" are referred to the outline of the device. In addition, in the description of the present application, the term "includes" means "includes but is not limited to". The terms first, second, third, etc. are only used as a label and do not impose a numerical requirement or establish an order.

[0043] In the present application, "and / or" describes the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B, which can represent the following cases: A exists alone, A and B exist together, and B exists alone. Wherein A and B can be singular or plural.

[0044] In the present application, "at least one" means one or more, and "multiple" means two or more. "One or more", "at least one of the following" or the like means any combination of these items, including any combination of single item or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can represent a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, wherein a, b, and c can be single or multiple.

[0045] Various embodiments of the present application can exist in the form of a range; it should be understood that the description in the form of a range is only for the convenience and brevity, and should not be understood as a hard limit on the scope of the present application; therefore, it should be considered that the described range has been specifically disclosed all possible sub-ranges and single values within the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. In addition, whenever a numerical range is indicated in the present application, it refers to any cited number (fraction or integer) within the indicated range.

[0046] The technical solutions of the present application are as follows:

[0047] In a first aspect, the embodiments of the present application provide a non-woven fabric for an atomizing core, comprising a lower fiber layer, a middle fiber layer and an upper fiber layer which are stacked.

[0048] Specifically, the upper fiber layer comprises the following components in mass fraction: 30-40 parts of first polyimide fibers, and 60-70 parts of pure cotton fibers.

[0049] The middle fiber layer comprises the following components in mass fraction: 10-50 parts of second polyimide fibers, 20-40 parts of pure cotton fibers, and 30-50 parts of viscose fibers.

[0050] The lower fiber layer comprises the following components in mass fraction: 100 parts of viscose fibers.

[0051] The fineness of the first polyimide fibers is greater than that of the second polyimide fibers.

[0052] It can be understood that, when the non-woven fabric of the present application is applied to the atomizing core, the upper fiber layer is the high-temperature heating side that contacts the heating body of the atomizing core.

[0053] With the above scheme, by stacking the lower fiber layer, the middle fiber layer and the upper fiber layer, the upper fiber layer is blended with first polyimide fibers and pure cotton fibers, the middle fiber layer is blended with second polyimide fibers, pure cotton fibers and viscose fibers, and the lower layer is viscose fibers. Moreover, the fineness of the first polyimide fibers is greater than that of the second polyimide fibers, so that the heat resistance of the first polyimide fibers is better than that of the second polyimide fibers. Based on the material matching of the above layers, the heat resistance of the non-woven fabric gradually decreases from the upper fiber layer to the lower fiber layer, and the oil guiding performance gradually increases from the upper fiber layer to the lower fiber layer. Therefore, the non-woven fabric of the present application has excellent heat resistance and oil guiding performance, and avoids weakening the oil guiding performance of the non-woven fabric after adding polyimide fibers. When applied to the atomizing core, the service life of the atomizing core can be prolonged.

[0054] As an optional scheme, in an embodiment of the present application, the first polyimide fibers are thick denier polyimide fibers, and the second polyimide fibers are thin denier polyimide fibers.

[0055] As a preferred scheme, the first polyimide fibers are profiled cross-section polyimide fibers, and the second polyimide fibers are profiled cross-section polyimide fibers.

[0056] It can be understood that the profiled cross-section fiber is a polyimide fiber with a special cross-sectional shape (non-circular), which has a triangular, star-shaped, fan-shaped or multi-leaf-shaped cross-sectional shape. Since the profiled cross-section fiber has a larger surface area than the circular cross-section fiber of the same mass, the profiled cross-section fiber has both heat resistance and better oil guiding performance.

[0057] Adopting the above special-shaped cross-section scheme, the oil guiding performance of the first polyimide fiber and the second polyimide fiber is further improved.

[0058] More preferably, the cross-sectional shape of the first polyimide fiber and the second polyimide fiber is trilobal.

[0059] As an optional scheme, in another embodiment of the present application, the first polyimide fiber is obtained by surface modification treatment of a first fiber raw material, and / or the second polyimide fiber is obtained by surface modification treatment of a second fiber raw material.

[0060] By adopting such a scheme, the surface microstructure of the first polyimide fiber and the second polyimide fiber is changed by surface modification treatment, the roughness of the fiber surface is increased, and the oil guiding performance is improved, so that the formed non-woven fabric has heat resistance and improved oil guiding performance.

[0061] As an optional scheme, the surface modification treatment includes one or more of chemical modification treatment and physical modification treatment.

[0062] Specifically, the chemical modification treatment is a specific alkali treatment and acid treatment, and the surface of the fiber raw material is subjected to acid-alkali etching treatment. The fiber raw material is subjected to first etching treatment by an alkaline solution, and second etching treatment by an acidic solution, so that the surface of the first heat-resistant fiber and the second heat-resistant fiber has a discontinuous crack structure, the roughness of the fiber surface is increased, the oil guiding performance is improved, and the oil guiding performance of the formed non-woven fabric is improved. The improvement of the oil guiding rate, on the one hand, improves the atomization efficiency and is beneficial to heat balance in the atomization process, and on the other hand, avoids the problem of dry burning and prolongs the service life of the atomization core.

[0063] The physical modification treatment is plasma treatment or other physical modification treatment. The plasma treatment can increase the chemical groups on the surface of the fiber, increase the roughness of the fiber surface, and improve the oil guiding performance of the fiber and the formed non-woven fabric. In addition, the plasma treatment can further remove the oil on the surface of the fiber raw material, greatly improve the cleanliness of the fiber material surface, and thus bring better taste restoration.

[0064] As a preferred scheme, the first fiber raw material is a thick denier polyimide fiber, and the second fiber raw material is a thin denier polyimide fiber.

[0065] As a further preferred scheme, the first fiber raw material is a special-shaped cross-section polyimide fiber, and the second fiber raw material is a special-shaped cross-section polyimide fiber.

[0066] Adopting the above special-shaped cross-section scheme, the oil guiding performance of the first polyimide fiber and the second polyimide fiber is further improved.

[0067] As an optional solution, in some embodiments, the viscose fiber is fine denier viscose fiber.

[0068] In the present embodiment, by using fine denier viscose fiber for the viscose fiber, the consistency and uniformity of the fiber distribution in the middle fiber layer and the lower fiber layer are improved, and the oil guiding performance is improved.

[0069] As an optional solution, in some embodiments, the length of the first polyimide fiber ranges from 38 mm to 60 mm, and the fineness of the first polyimide fiber ranges from 2.2 dtex to 6.0 dtex.

[0070] The length of the second polyimide fiber ranges from 38 mm to 60 mm, and the fineness of the second polyimide fiber ranges from 0.9 dtex to 1.3 dtex.

[0071] The length of the viscose fiber ranges from 18 mm to 60 mm, and the fineness of the viscose fiber ranges from 0.5 dtex to 3.8 dtex.

[0072] The length of the pure cotton fiber ranges from 18 mm to 38 mm, and the fineness of the pure cotton fiber ranges from 0.5 dtex to 3.8 dtex.

[0073] More preferably, the length of the pure cotton fiber ranges from 28 mm to 31 mm, and the fineness of the pure cotton fiber ranges from 1.4 dtex to 2.2 dtex.

[0074] The length of the viscose fiber ranges from 38 mm to 51 mm, and the fineness of the viscose fiber ranges from 0.9 dtex to 1.3 dtex.

[0075] As an optional solution, in some embodiments, the thickness ratio of the upper fiber layer ranges from 40% to 50%, the thickness ratio of the middle fiber layer ranges from 25% to 30%, and the thickness ratio of the lower fiber layer ranges from 25% to 30%, based on the overall thickness of the non-woven fabric.

[0076] It can be understood that the thickness ratio of each fiber layer can be controlled by the feeding mass ratio of each layer, that is, the more the feeding, the thicker the corresponding fiber layer.

[0077] Of course, the fineness of the fiber added in the fiber layer also affects the thickness of the fiber layer, for example, under the same feeding mass, the fineness of the first polyimide fiber in the upper fiber layer is greater than the fineness of the second polyimide fiber in the lower fiber layer, and under the same reinforcement process, the upper fiber layer is relatively not easy to be compressed, so that the upper fiber layer presents a more fluffy state, and the thickness is correspondingly greater.

[0078] With the above thickness control scheme, by limiting the upper fiber layer in the non-woven fabric to have a larger thickness ratio, the upper fiber layer obtains better high temperature resistance. At the same time, based on the premise that the first polyimide fiber adopts a coarse denier polyimide fiber and the second polyimide fiber adopts a fine denier polyimide fiber, the loft of the upper fiber layer is higher, the porosity is relatively higher, and the oil storage performance is higher, which ensures sufficient oil supply, thereby reducing the possibility of dry burning and paste core. In addition, under this thickness scheme, the oil guiding effect of the middle fiber layer and the lower fiber layer can be avoided.

[0079] As an optional scheme, the mass ratio of the upper fiber layer is 20%-40%, the mass ratio of the middle fiber layer is 20%-40%, and the mass ratio of the lower fiber layer is 20%-40%.

[0080] The porosity of the upper fiber layer is 85%-95%, the porosity of the middle fiber layer is 80%-90%, and the porosity of the lower fiber layer is 75%-85%.

[0081] It can be understood that the thickness, mass and porosity of each fiber layer in the above non-woven fabric are not independent of each other, but are realized by the material selection, feeding ratio and reinforcement process of each fiber layer.

[0082] With the above thickness, mass and porosity scheme, and in combination with the material selection and ratio of each layer, the non-woven fabric of the present application has excellent heat resistance, improves the attenuation of oil guiding performance and oil storage performance, and improves the comprehensive performance of the non-woven fabric.

[0083] As an optional scheme, in some embodiments, the overall mass of the non-woven fabric for the atomizing core is 60-150 g / m 2 , and the overall thickness of the non-woven fabric for the atomizing core is 0.4-1.2 mm.

[0084] Correspondingly, as shown in Figure 1 , the present application also provides a preparation method of the above non-woven fabric for the atomizing core, comprising the following steps:

[0085] S110: Mix the first polyimide fiber and the pure cotton fiber according to the proportion, and perform carding and laying to obtain an upper uniform fiber web.

[0086] S120: Mix the second polyimide fiber, the pure cotton fiber and the viscose fiber according to the proportion, and perform carding and laying to obtain a middle uniform fiber web.

[0087] S130: Card and lay the viscose fiber to obtain a lower uniform fiber web.

[0088] S140: reinforcing the whole of the upper layer uniform fiber web, the middle layer uniform fiber web and the lower layer uniform fiber web to obtain a non-woven fabric for the atomizing core.

[0089] In some embodiments, step S110 mainly includes the following steps:

[0090] S111: weighing the first polyimide fibers and the pure cotton fibers according to the proportion.

[0091] S112: opening the weighed first polyimide fibers and pure cotton fibers, feeding the opened fibers into a fiber bin, and mixing the first polyimide fibers and the pure cotton fibers thoroughly, and then making the mixed fibers into a uniform fiber web.

[0092] S113: entering a carding process, the carding process adopts a two-card-one-lay production line, and the fiber webs output by two carding machines are simultaneously fed into a cross-laying machine to be laid to obtain an upper layer uniform fiber web.

[0093] In some embodiments, step S120 mainly includes the following steps:

[0094] S121: weighing the second polyimide fibers, the pure cotton fibers and the viscose fibers according to the proportion.

[0095] S122: opening the weighed second polyimide fibers, the pure cotton fibers and the viscose fibers, feeding the opened fibers into a fiber bin, and mixing the second polyimide fibers, the pure cotton fibers and the viscose fibers thoroughly, and then making the mixed fibers into a uniform fiber web.

[0096] S123: entering a carding process, the carding process adopts a two-card-one-lay production line, and the fiber webs output by two carding machines are simultaneously fed into a cross-laying machine to be laid to obtain a middle layer uniform fiber web.

[0097] In some embodiments, step S130 mainly includes the following steps:

[0098] S131: weighing a certain amount of viscose fibers.

[0099] S132: opening the weighed viscose fibers, feeding the opened fibers into a fiber bin, and mixing the fibers thoroughly, and then making the mixed fibers into a uniform fiber web.

[0100] S133: entering a carding process, the carding process adopts a two-card-one-lay production line, and the fiber webs output by two carding machines are simultaneously fed into a cross-laying machine to be laid to obtain a lower layer uniform fiber web.

[0101] As an optional solution, in some embodiments, step S140 mainly includes the following steps:

[0102] S141: sequentially place the upper uniform web, the middle uniform web and the lower uniform web from top to bottom, and perform a hot rolling process to obtain a three-layer web composite material.

[0103] Specifically, in step S141, the temperature of the hot rolling process is in the range of 120-160°C.

[0104] S142: pre-punching the three-layer web composite material.

[0105] Specifically, in step S142, the pre-punching water pressure is in the range of 1-10 bar.

[0106] S143: multi-pass forward and reverse hydroentanglement of the pre-punched three-layer web composite material and drying to obtain a non-woven fabric.

[0107] As an optional solution, in step S143, the hydroentanglement pressure of the multi-pass forward and reverse hydroentanglement is in the range of 20-50 bar, and the hydroentanglement pressure gradually increases, the jet time of the forward and reverse hydroentanglement pressure is 0.5-15 min, the linear speed of the hydroentanglement treatment is in the range of 30-100 m / min, and the drying temperature is in the range of 100-140°C.

[0108] Using such hydroentanglement treatment parameters, the dispersion and combination of different fibers are controlled, so that the formed non-woven fabric has better uniformity, and the combination of each fiber layer is better.

[0109] As a specific solution, the multi-pass forward and reverse hydroentanglement includes 7 passes of forward and reverse hydroentanglement, four forward and three reverse (forward-reverse-forward-reverse-forward-reverse-forward), corresponding to the order of forward and reverse hydroentanglement, the hydroentanglement pressure is 20 bar, 20 bar, 30 bar, 30 bar, 35 bar, 35 bar and 35 bar, respectively.

[0110] Using the above hydroentanglement solution, by reducing the single-pass hydroentanglement pressure and gradually increasing the multi-pass hydroentanglement pressure, the non-woven fabric as a whole has a smooth surface and a soft and fluffy effect.

[0111] As another optional solution, the hydroentanglement pressures of adjacent passes of forward and reverse hydroentanglement are different, for example, the upper fiber layer is directly opposite the hydroentanglement head during forward hydroentanglement, and the lower fiber layer is directly opposite the hydroentanglement head during reverse hydroentanglement, the hydroentanglement pressure of forward hydroentanglement is controlled to be less than that of reverse hydroentanglement, so that the upper fiber layer has greater fluffiness, thereby having higher porosity, improving heat resistance and oil storage performance.

[0112] As an optional solution, in some embodiments, before step S110, the preparation method further comprises the following steps:

[0113] A first fiber raw material is subjected to surface modification treatment to obtain first polyimide fibers, and a second fiber raw material is subjected to surface modification treatment to obtain second polyimide fibers.

[0114] As a specific solution, the surface modification treatment mainly includes the following steps:

[0115] S101: An alkaline solution is prepared, and potassium hydroxide (KOH) is prepared into an alkaline solution of 15-25 g / L, and the alkaline solution is cooled to room temperature (here, room temperature refers to less than or equal to 30°C).

[0116] S102: The fiber raw material (first fiber raw material or second fiber raw material) is added to the alkaline solution, the bath ratio is 1:10, and is soaked for 20-40 minutes, taken out and dehydrated.

[0117] S103: The fiber surface is washed with clean water to remove excess alkaline substances, and the acceptance standard is that the pH value of the water solution after the fiber is soaked for 20-30 minutes approaches 7.0, and is dehydrated to a free water state, to obtain an intermediate state fiber.

[0118] S104: An acid solution is prepared, and glacial acetic acid (CH3COOH) is prepared into an acid solution of 5-10 g / L.

[0119] S105: The intermediate state fiber is added to the acid solution, the bath ratio is 1:10, and is soaked for 30-60 minutes, taken out and dehydrated.

[0120] S106: The fiber surface is washed with clean water to remove excess alkaline substances, and the acceptance standard is that the pH value of the water solution after the fiber is soaked for 30-60 minutes approaches 7.0, and is dehydrated to a free water state, and the fiber is dried to a constant weight at 80-100°C, to obtain the first polyimide fiber or the second polyimide fiber subjected to surface modification treatment.

[0121] By using such a solution, the fiber raw material is subjected to degreasing and first etching treatment by the alkaline solution, and second etching treatment by the acid solution, so as to reduce the surface energy of the fiber raw material to obtain the first polyimide fiber or the second polyimide fiber, thereby improving the oil guiding performance of the first polyimide fiber or the second polyimide fiber, and improving the oil guiding rate of the non-woven fabric after forming.

[0122] The present application will be specifically described below through specific examples. The following examples are only part of the examples of the present application, and are not a limitation of the present application. The raw materials used in the following examples are all commercially available products unless otherwise specified.

[0123] It should be noted that for the fibers involved in the following examples or comparative examples of the present invention, their fineness and length are marked in parentheses. For example, polyimide fiber (2.2 dtex × 60 mm) means that the fineness of the polyimide fiber is 2.2 dtex and the length is 60 mm.

[0124] The following methods are used to test the thickness and gram weight of the non-woven fabrics involved in the following examples and comparative examples:

[0125] Thickness test: Use a commercially available micrometer thickness gauge to measure the thickness of the non-woven fabric. Measure 30 points along the width direction of the non-woven fabric and calculate the average value, with the unit being mm.

[0126] Gram weight test: On the width direction of the non-woven fabric, cut circular samples with a diameter of 50 cm 2 at 30 different positions, weigh them, and calculate the average value, with the unit being g / m 2 .

[0127] Test method for the oil guiding performance and oil storage performance of non-woven fabrics:

[0128] Cut the non-woven fabric into cotton strips with a size of ⑧ mm × 30 mm, with a quantity of 20. Place them in a standard environment (temperature 20 °C, relative humidity 65%) and balance for 24 hours. Use a Mayzum MAL-PR124 full-automatic atomizing core oil guiding rate analyzer to test the oil guiding performance of the non-woven fabric cotton strips; the e-liquid specifications are: pineapple e-liquid, nicotine content 0 mg, weight ratio of propylene glycol to glycerol 50 / 50. Load the e-liquid into the constant-temperature inner cup, use a standard fixture to hang the cotton strip sample on the fixture, and then click the start recording button in the test software. Subsequently, the instrument will automatically adjust the contact point position. When the lower end of the cotton strip just touches the e-liquid, the test platform stops rising and starts timing; while the non-woven fabric cotton strip is absorbing oil, the test equipment will simultaneously record the oil absorption values of the cotton strip at all time points during the e-liquid climbing process. Take the oil absorption M1 (g) of the non-woven fabric cotton strip at 90 s and the initial weight M0 (g) of the cotton strip.

[0129] Oil guiding performance: Use the change amount of the oil absorption of the non-woven fabric cotton strip per unit time to characterize the oil guiding performance of the cotton strip. In this example, calculate the oil guiding rate D = M1 / 90 s using the oil absorption M1 (g) at 90 s, with the unit being mg / s. Test the M1 / 90 s of 20 samples and calculate the average value as the characterization index of the final oil guiding performance of the non-woven fabric cotton strip.

[0130] Oil storage performance of non-woven fabric: The oil storage performance of the cotton strip is characterized by the oil absorption of the non-woven fabric cotton strip per unit weight. In this embodiment, the oil absorption M1 (g) at 90 s is compared with the initial weight M0 of the cotton strip, and the oil storage rate C = M1 / M0 is calculated, with the unit of g / g. The average value of M1 / M0 of 20 samples is obtained as the characterization index of the final oil storage performance of the non-woven fabric cotton strip.

[0131] Lifetime test method of atomization core:

[0132] 1) Adjusting the core and assembling the atomization core: Cut the non-woven fabric into cotton strips with a size of 8 mm × 30 mm, and combine the cotton strips with other viscose non-woven fabrics or pure cotton hydrospun non-woven fabrics to obtain the most suitable cotton strip for adjusting the core combination of the atomization core, and then assemble it into the corresponding atomization core.

[0133] 2) Lifetime suction test: Install the atomization core into the atomizer, inject 70% of the e-juice with the flavor of big smoke pineapple (VG / PG = 7 / 3), moisten the core for 5 minutes, then install it into a fully charged main unit (providing power), suck 3 - 5 puffs at the default power (35 W), and then suck 3 - 5 puffs at the maximum power (40 W), with each puff lasting for 2 - 3 seconds;

[0134] 3) Take 8 samples, use a smoking machine (model FH-Y108), suck for 3 seconds and stop for 5 seconds. Stop for 30 seconds every 5 puffs. The smoking speed is 100 ml / second. Stop when the e-juice reaches about 1 / 2 of the oil inlet hole of the atomization core, add e-juice, and continue to repeat step 2). During this period, manually confirm whether the atomization core is abnormal. Stop the test until a burnt core and abnormal smell continuously appear in the taste, and record the total volume of the e-juice sucked during the whole process as the lifetime value of the atomization core, with the unit of ml.

[0135] Example 1

[0136] (1) Prepare a 25 g / L alkaline solution with potassium hydroxide (KOH), and wait for the alkaline solution to cool to room temperature. According to the bath ratio of 1:10, add coarse denier polyimide fibers (2.2 dtex × 60 mm, trilobal cross-section) to the alkaline solution, soak for 30 minutes充分浸泡, take out and dehydrate. Wash the excess alkaline substances on the fiber surface with clean water. The acceptance standard for washing is that the pH value of the aqueous solution after the fiber is soaked for 20 minutes is close to 7.0, and dehydrate until there is no free water, obtaining the intermediate state fiber.

[0137] Prepare an acidic solution of 6 g / L by using glacial acetic acid (CH3COOH). According to the bath ratio of 1:10, add the intermediate-state fiber into the acidic solution, soak it fully for 20 minutes, take it out and dehydrate. Wash the excess alkaline substances on the fiber surface with clear water. The acceptance standard for washing is that the pH value of the aqueous solution after the fiber is soaked for 20 minutes is close to 7.0, and dehydrate until there is no free water. Dry the fiber to a constant weight at a drying temperature of 80 °C to obtain the surface-modified coarse denier polyimide fiber.

[0138] (2) Perform the surface modification treatment in step (1) on the fine denier polyimide fiber (1.22 tex × 38 mm, trilobal cross-section) to obtain the surface-modified fine denier polyimide fiber.

[0139] (3) Weigh 160 kg of the surface-modified coarse denier polyimide fiber (2.2 dtex × 60 mm, trilobal cross-section) and 240 kg of pure cotton fiber (white cotton grade 2, length 27 mm, main micronaire value grade B) respectively.

[0140] Loosen the weighed surface-modified coarse denier polyimide fiber and pure cotton fiber respectively, feed the loosened fibers into the fiber bin, and after the two kinds of fibers are fully mixed, make the mixed fibers into a uniform web. Enter the carding process. The carding process uses a two-card-one-laying production line. The webs output by the two carding machines are fed to the cross lapping machine at the same time for lapping to obtain the upper-layer uniform web.

[0141] (4) Weigh 90 kg of the surface-modified fine denier polyimide fiber (1.22 dtex × 38 mm, trilobal cross-section), 90 kg of pure cotton fiber (white cotton grade 2, length 27 mm, main micronaire value grade B), and 120 kg of fine denier viscose fiber (0.9 dtex × 38 mm) respectively.

[0142] Loosen the weighed surface-modified fine denier polyimide fiber, pure cotton fiber and fine denier viscose fiber respectively, feed the loosened fibers into the fiber bin, and after the three kinds of fibers are fully mixed, make the mixed fibers into a uniform web. Enter the carding process. The carding process uses a two-card-one-laying production line. The webs output by the two carding machines are fed to the cross lapping machine at the same time for lapping to obtain the middle-layer uniform web.

[0143] (5) Weigh 300 kg of fine denier viscose fiber (0.9 dtex × 38 mm).

[0144] Loosen the weighed viscose fiber, feed the loosened fibers into the fiber bin, and after full mixing, make the mixed fibers into a uniform web. Enter the carding process. The carding process uses a two-card-one-laying production line. The webs output by the two carding machines are fed to the cross lapping machine at the same time for lapping to obtain the lower-layer uniform web.

[0145] (6) The upper uniform fiber web, the middle uniform fiber web and the lower uniform fiber web are placed from top to bottom and subjected to a 120°C hot rolling process to complete the initial composite process, and a three-layer fiber web composite material is obtained.

[0146] The three-layer fiber web composite material is fed into a hydroentangling machine for pre-punching treatment. The pre-punching water pressure is 5 bar. The pre-punched uniform fiber web is hydroentangled seven times in both directions, four times in the forward direction and three times in the reverse direction (forward-reverse-forward-reverse-forward-reverse-forward). The hydroentangling pressures are 20 bar, 20 bar, 30 bar, 30 bar, 35 bar, 35 bar, and 35 bar, respectively. The spraying time is controlled at 2 minutes, and the production line speed is 35 meters per minute. After that, it is dried at 120°C to obtain an intermediate nonwoven fabric.

[0147] The obtained intermediate nonwoven fabric is dried and surface calendered by a hot rolling process at 120℃, and then dried at 100℃ to obtain the nonwoven fabric (final product) used for the atomizing core.

[0148] The nonwoven fabric (final product) prepared above has an overall basis weight of 90 g / m². 2 The overall thickness is 0.565mm.

[0149] Example 2

[0150] (1) Prepare an alkaline solution of 25 g / L using potassium hydroxide (KOH) and allow it to cool to room temperature. Add coarse denier polyimide fibers (2.2 dtex × 60 mm, trilobal cross-section) to the alkaline solution at a bath ratio of 1:10, soak for 30 minutes, remove and dehydrate. Rinse the fiber surface with clean water to remove excess alkaline substances. The washing acceptance standard is that the pH value of the aqueous solution after soaking the fiber for 20 minutes is close to 7.0. Dehydrate until there is no free water to obtain intermediate state fibers.

[0151] Prepare a 6 g / L acidic solution using glacial acetic acid (CH3COOH). Add the intermediate-state fibers to the acidic solution at a bath ratio of 1:10, soak for 20 minutes, then remove and dehydrate. Rinse the fiber surface with clean water to remove excess alkaline substances. The washing acceptance standard is that the pH value of the aqueous solution after 20 minutes of fiber soaking is close to 7.0. Dehydrate until no free water remains, and dry the fibers at 80℃ to constant weight to obtain surface-modified coarse denier polyimide fibers.

[0152] (2) The fine denier polyimide fiber (1.22 tex × 38 mm, trilobal cross section) is subjected to the surface modification treatment of step (1) to obtain the surface-modified fine denier polyimide fiber.

[0153] (3) Weigh 150 kg of surface-modified coarse denier polyimide fiber (2.2 dtex × 60 mm, trilobal cross section) and 350 kg of pure cotton fiber (white cotton grade 2, length 27 mm, main micronaire value grade B) respectively.

[0154] The surface-modified coarse denier polyimide fibers and pure cotton fibers are weighed and opened separately. The opened fibers are fed into the fiber bin to fully mix the two types of fibers. The mixed fibers are then formed into a uniform fiber web. The fiber web then enters the carding process, which uses a two-carding-one-laying production line. The fiber webs output from the two carding machines are simultaneously fed to a cross-laying machine to lay the web and obtain a uniform upper layer fiber web.

[0155] (4) Weigh out 75 kg of surface-modified fine denier polyimide fiber (1.22 dtex × 38 mm, trilobal cross section), 50 kg of pure cotton fiber (white cotton grade 2, length 27 mm, main micronaire value grade B) and 125 kg of fine denier viscose fiber (0.9 dtex × 38 mm).

[0156] The surface-modified fine denier polyimide fibers, pure cotton fibers, and fine denier viscose fibers are weighed and opened separately. The opened fibers are then fed into a fiber bin to fully mix the three types of fibers. The mixed fibers are then formed into a uniform fiber web. The web then enters the carding process, which uses a two-carding-one-laying production line. The fiber webs output from two carding machines are simultaneously fed to a cross-laying machine to lay the web and obtain a uniform middle layer fiber web.

[0157] (5) Weigh 250 kg of fine denier viscose fiber (0.9 dtex × 38 mm).

[0158] The weighed viscose fibers are opened and fed into a fiber bin. After thorough mixing, the mixed fibers are formed into a uniform fiber web. The web then enters the carding process, which uses a two-carding-one-laying production line. The fiber webs output from two carding machines are simultaneously fed to a cross-laying machine to lay the web and obtain a uniform lower layer.

[0159] (6) The upper uniform fiber web, the middle uniform fiber web and the lower uniform fiber web are placed from top to bottom and subjected to a 120°C hot rolling process to complete the initial composite process, and a three-layer fiber web composite material is obtained.

[0160] The three-layer fiber web composite material is fed into a hydroentangling machine for pre-punching treatment. The pre-punching water pressure is 5 bar. The pre-punched uniform fiber web is hydroentangled seven times in both directions, four times in the forward direction and three times in the reverse direction (forward-reverse-forward-reverse-forward-reverse-forward). The hydroentangling pressures are 20 bar, 20 bar, 30 bar, 30 bar, 35 bar, 35 bar, and 35 bar, respectively. The spraying time is controlled at 2 minutes, and the production line speed is 35 meters per minute. After that, it is dried at 120°C to obtain an intermediate nonwoven fabric.

[0161] The obtained intermediate nonwoven fabric is dried and surface calendered by a hot rolling process at 120℃, and then dried at 100℃ to obtain the nonwoven fabric (final product) used for the atomizing core.

[0162] The nonwoven fabric (final product) prepared above has an overall basis weight of 120 g / m². 2 The overall thickness is 0.690mm.

[0163] Example 3

[0164] (1) Prepare an alkaline solution of 25 g / L using potassium hydroxide (KOH) and allow it to cool to room temperature. Add coarse denier polyimide fibers (2.2 dtex × 60 mm, trilobal cross-section) to the alkaline solution at a bath ratio of 1:10, soak for 30 minutes, remove and dehydrate. Rinse the fiber surface with clean water to remove excess alkaline substances. The washing acceptance standard is that the pH value of the aqueous solution after soaking the fiber for 20 minutes is close to 7.0. Dehydrate until there is no free water to obtain intermediate state fibers.

[0165] Prepare a 6 g / L acidic solution using glacial acetic acid (CH3COOH). Add the intermediate-state fibers to the acidic solution at a bath ratio of 1:10, soak for 20 minutes, then remove and dehydrate. Rinse the fiber surface with clean water to remove excess alkaline substances. The washing acceptance standard is that the pH value of the aqueous solution after 20 minutes of fiber soaking is close to 7.0. Dehydrate until no free water remains, and dry the fibers at 80℃ to constant weight to obtain surface-modified coarse denier polyimide fibers.

[0166] (2) The fine denier polyimide fiber (1.22 tex × 38 mm, trilobal cross section) is subjected to the surface modification treatment of step (1) to obtain the surface-modified fine denier polyimide fiber.

[0167] (3) Weigh 180 kg of surface-modified coarse denier polyimide fiber (2.2 dtex × 60 mm, trilobal cross section) and 270 kg of pure cotton fiber (white cotton grade 2, length 27 mm, main micronaire value grade B) respectively.

[0168] The surface-modified coarse denier polyimide fibers and pure cotton fibers are weighed and opened separately. The opened fibers are fed into the fiber bin to fully mix the two types of fibers. The mixed fibers are then formed into a uniform fiber web. The fiber web then enters the carding process, which uses a two-carding-one-laying production line. The fiber webs output from the two carding machines are simultaneously fed to a cross-laying machine to lay the web and obtain a uniform upper layer fiber web.

[0169] (4) Weigh out 82.5 kg of surface-modified fine denier polyimide fiber (1.22 dtex × 38 mm, trilobal cross section), 82.5 kg of pure cotton fiber (white cotton grade 2, length 27 mm, main micronaire value grade B) and 110 kg of fine denier viscose fiber (0.9 dtex × 38 mm).

[0170] The surface-modified fine denier polyimide fibers, pure cotton fibers, and fine denier viscose fibers are weighed and opened separately. The opened fibers are then fed into a fiber bin to fully mix the three types of fibers. The mixed fibers are then formed into a uniform fiber web. The web then enters the carding process, which uses a two-carding-one-laying production line. The fiber webs output from two carding machines are simultaneously fed to a cross-laying machine to lay the web and obtain a uniform middle layer fiber web.

[0171] (5) Weigh 275 kg of fine denier viscose fiber (0.9 dtex × 38 mm).

[0172] The weighed viscose fibers are opened and fed into a fiber bin. After thorough mixing, the mixed fibers are formed into a uniform fiber web. The web then enters the carding process, which uses a two-carding-one-laying production line. The fiber webs output from two carding machines are simultaneously fed to a cross-laying machine to lay the web and obtain a uniform lower layer.

[0173] (6) The upper uniform fiber web, the middle uniform fiber web and the lower uniform fiber web are placed from top to bottom and subjected to a 120°C hot rolling process to complete the initial composite process, and a three-layer fiber web composite material is obtained.

[0174] The three-layer fiber web composite material is fed into a hydroentangling machine for pre-punching treatment. The pre-punching water pressure is 5 bar. The pre-punched uniform fiber web is hydroentangled seven times in both directions, four times in the forward direction and three times in the reverse direction (forward-reverse-forward-reverse-forward-reverse-forward). The hydroentangling pressures are 20 bar, 20 bar, 30 bar, 30 bar, 35 bar, 35 bar, and 35 bar, respectively. The spraying time is controlled at 2 minutes, and the production line speed is 35 meters per minute. After that, it is dried at 120°C to obtain an intermediate nonwoven fabric.

[0175] The obtained intermediate nonwoven fabric is dried and surface calendered by a hot rolling process at 120℃, and then dried at 100℃ to obtain the nonwoven fabric (final product) used for the atomizing core.

[0176] The nonwoven fabric (final product) prepared above has an overall basis weight of 90 g / m². 2 The overall thickness is 0.639mm.

[0177] Comparative Example 1

[0178] (1) Prepare an alkaline solution of 25 g / L using potassium hydroxide (KOH) and allow it to cool to room temperature. Add fine denier polyimide fibers (1.22 tex × 38 mm, trilobal cross-section) to the alkaline solution at a bath ratio of 1:10 and soak them thoroughly for 30 minutes. Remove and dehydrate. Rinse the fiber surface with clean water to remove excess alkaline substances. The cleaning acceptance standard is that the pH value of the aqueous solution after soaking the fiber for 20 minutes is close to 7.0. Dehydrate until there is no free water to obtain intermediate-state fibers.

[0179] Prepare a 6 g / L acidic solution using glacial acetic acid (CH3COOH). Add the intermediate-state fibers to the acidic solution at a bath ratio of 1:10, soak for 20 minutes, then remove and dehydrate. Rinse the fiber surface with clean water to remove excess alkaline substances. The washing acceptance standard is that the pH value of the aqueous solution after 20 minutes of fiber soaking is close to 7.0. Dehydrate until no free water remains, and dry the fibers at 80℃ to constant weight to obtain surface-modified fine denier polyimide fibers.

[0180] (2) Weigh out 150 kg of surface-modified fine denier polyimide fiber (1.22 dtex × 38 mm, trilobal cross section), 150 kg of pure cotton fiber (white cotton grade 2, length 27 mm, main micronaire value grade B) and 200 kg of fine denier viscose fiber (0.9 dtex × 38 mm).

[0181] The surface-modified fine denier polyimide fibers, pure cotton fibers, and fine denier viscose fibers are weighed and opened separately. The opened fibers are then fed into a fiber bin to fully mix the three types of fibers. The mixed fibers are then formed into a uniform fiber web. The web then enters the carding process, which uses a two-carding-one-laying production line. The fiber webs output from two carding machines are simultaneously fed to a cross-laying machine to lay the web and obtain a uniform middle layer fiber web.

[0182] (3) Weigh 500 kg of fine denier viscose fiber (0.9 dtex × 38 mm).

[0183] The weighed viscose fibers are opened and fed into a fiber bin. After thorough mixing, the mixed fibers are formed into a uniform fiber web. The web then enters the carding process, which uses a two-carding-one-laying production line. The fiber webs output from two carding machines are simultaneously fed to a cross-laying machine to lay the web and obtain a uniform lower layer.

[0184] (4) The middle layer uniform fiber web and the lower layer uniform fiber web are placed from top to bottom and subjected to a 120°C hot rolling process to complete the initial composite process, resulting in a two-layer fiber web composite material.

[0185] The two-layer fiber web composite material is fed into a hydroentangling machine for pre-punching treatment. The pre-punching water pressure is 5 bar. The pre-punched uniform fiber web is then hydroentangled seven times in both directions, four times in the forward direction and three times in the reverse direction (forward-reverse-forward-reverse-forward-reverse-forward). The hydroentangling pressures are 20 bar, 20 bar, 30 bar, 30 bar, 35 bar, 35 bar, and 35 bar, respectively. The spraying time is controlled at 2 minutes, and the production line speed is 35 meters per minute. Afterward, it is dried at 120°C to obtain an intermediate nonwoven fabric.

[0186] The obtained intermediate nonwoven fabric is dried and surface calendered by a hot rolling process at 120℃, and then dried at 100℃ to obtain the nonwoven fabric (final product) used for the atomizing core.

[0187] The nonwoven fabric (final product) prepared above has an overall basis weight of 90 g / m². 2 The overall thickness is 0.512mm.

[0188] Comparative Example 2

[0189] (1) Prepare an alkaline solution of 25 g / L using potassium hydroxide (KOH) and allow it to cool to room temperature. Add coarse denier polyimide fibers (2.2 dtex × 60 mm, trilobal cross-section) to the alkaline solution at a bath ratio of 1:10, soak for 30 minutes, remove and dehydrate. Rinse the fiber surface with clean water to remove excess alkaline substances. The washing acceptance standard is that the pH value of the aqueous solution after soaking the fiber for 20 minutes is close to 7.0. Dehydrate until there is no free water to obtain intermediate state fibers.

[0190] Prepare a 6 g / L acidic solution using glacial acetic acid (CH3COOH). Add the intermediate-state fibers to the acidic solution at a bath ratio of 1:10, soak for 20 minutes, then remove and dehydrate. Rinse the fiber surface with clean water to remove excess alkaline substances. The washing acceptance standard is that the pH value of the aqueous solution after 20 minutes of fiber soaking is close to 7.0. Dehydrate until no free water remains, and dry the fibers at 80℃ to constant weight to obtain surface-modified coarse denier polyimide fibers.

[0191] (2) Weigh 250 kg of surface-modified coarse denier polyimide fiber (2.2 dtex × 60 mm, trilobal cross section) and 250 kg of pure cotton fiber (white cotton grade 2, length 27 mm, main micronaire value grade B) respectively.

[0192] The surface-modified coarse denier polyimide fibers and pure cotton fibers are weighed and opened separately. The opened fibers are fed into the fiber bin to fully mix the two types of fibers. The mixed fibers are then formed into a uniform fiber web. The fiber web then enters the carding process, which uses a two-carding-one-laying production line. The fiber webs output from the two carding machines are simultaneously fed to a cross-laying machine to lay the web and obtain a uniform upper layer fiber web.

[0193] (3) Weigh 500g of fine denier viscose fiber (0.9dtex×38mm).

[0194] The weighed viscose fibers are opened and fed into a fiber bin. After thorough mixing, the mixed fibers are formed into a uniform fiber web. The web then enters the carding process, which uses a two-carding-one-laying production line. The fiber webs output from two carding machines are simultaneously fed to a cross-laying machine to lay the web and obtain a uniform lower layer.

[0195] (4) The upper uniform fiber web and the lower uniform fiber web are placed from top to bottom and subjected to a 120°C hot rolling process to complete the initial composite process, resulting in a two-layer fiber web composite material.

[0196] The two-layer fiber web composite material is fed into a hydroentangling machine for pre-punching treatment. The pre-punching water pressure is 5 bar. The pre-punched uniform fiber web is then hydroentangled seven times in both directions, four times in the forward direction and three times in the reverse direction (forward-reverse-forward-reverse-forward-reverse-forward). The hydroentangling pressures are 20 bar, 20 bar, 30 bar, 30 bar, 35 bar, 35 bar, and 35 bar, respectively. The spraying time is controlled at 2 minutes, and the production line speed is 35 meters per minute. Afterward, it is dried at 120°C to obtain an intermediate nonwoven fabric.

[0197] The obtained intermediate nonwoven fabric is dried and surface calendered by a hot rolling process at 120℃, and then dried at 100℃ to obtain the nonwoven fabric (final product) used for the atomizing core.

[0198] The nonwoven fabric (final product) prepared above has an overall basis weight of 90 g / m². 2 The overall thickness is 0.623mm.

[0199] Comparative Example 3

[0200] (1) Prepare an alkaline solution of 25 g / L using potassium hydroxide (KOH) and allow it to cool to room temperature. Add coarse denier polyimide fibers (2.2 dtex × 60 mm, trilobal cross-section) to the alkaline solution at a bath ratio of 1:10, soak for 30 minutes, remove and dehydrate. Rinse the fiber surface with clean water to remove excess alkaline substances. The washing acceptance standard is that the pH value of the aqueous solution after soaking the fiber for 20 minutes is close to 7.0. Dehydrate until there is no free water to obtain intermediate state fibers.

[0201] Prepare a 6 g / L acidic solution using glacial acetic acid (CH3COOH). Add the intermediate-state fibers to the acidic solution at a bath ratio of 1:10, soak for 20 minutes, then remove and dehydrate. Rinse the fiber surface with clean water to remove excess alkaline substances. The washing acceptance standard is that the pH value of the aqueous solution after 20 minutes of fiber soaking is close to 7.0. Dehydrate until no free water remains, and dry the fibers at 80℃ to constant weight to obtain surface-modified coarse denier polyimide fibers.

[0202] (2) The fine denier polyimide fiber (1.22 tex × 38 mm, trilobal cross section) is subjected to the surface modification treatment of step (1) to obtain the surface-modified fine denier polyimide fiber.

[0203] (3) Weigh 250 kg of surface-modified coarse denier polyimide fiber (2.2 dtex × 60 mm, trilobal cross section) and 250 kg of pure cotton fiber (white cotton grade 2, length 27 mm, main micronaire value grade B) respectively.

[0204] The surface-modified coarse denier polyimide fibers and pure cotton fibers are weighed and opened separately. The opened fibers are fed into the fiber bin to fully mix the two types of fibers. The mixed fibers are then formed into a uniform fiber web. The fiber web then enters the carding process, which uses a two-carding-one-laying production line. The fiber webs output from the two carding machines are simultaneously fed to a cross-laying machine to lay the web and obtain a uniform upper layer fiber web.

[0205] (4) Weigh out 150 kg of surface-modified fine denier polyimide fiber (1.22 dtex × 38 mm, trilobal cross section), 150 kg of pure cotton fiber (white cotton grade 2, length 27 mm, main micronaire value grade B) and 200 kg of fine denier viscose fiber (0.9 dtex × 38 mm).

[0206] The surface-modified fine denier polyimide fibers, pure cotton fibers, and fine denier viscose fibers are weighed and opened separately. The opened fibers are then fed into a fiber bin to fully mix the three types of fibers. The mixed fibers are then formed into a uniform fiber web. The web then enters the carding process, which uses a two-carding-one-laying production line. The fiber webs output from two carding machines are simultaneously fed to a cross-laying machine to lay the web and obtain a uniform middle layer fiber web.

[0207] (5) The upper uniform fiber web and the middle uniform fiber web are placed from top to bottom and subjected to a 120°C hot rolling process to complete the initial composite process, resulting in a two-layer fiber web composite material.

[0208] The two-layer fiber web composite material is fed into a hydroentangling machine for pre-punching treatment. The pre-punching water pressure is 5 bar. The pre-punched uniform fiber web is then hydroentangled seven times in both directions, four times in the forward direction and three times in the reverse direction (forward-reverse-forward-reverse-forward-reverse-forward). The hydroentangling pressures are 20 bar, 20 bar, 30 bar, 30 bar, 35 bar, 35 bar, and 35 bar, respectively. The spraying time is controlled at 2 minutes, and the production line speed is 35 meters per minute. Afterward, it is dried at 120°C to obtain an intermediate nonwoven fabric.

[0209] The obtained intermediate nonwoven fabric is dried and surface calendered by a hot rolling process at 120℃, and then dried at 100℃ to obtain the nonwoven fabric (final product) used for the atomizing core.

[0210] The nonwoven fabric (final product) prepared above has an overall basis weight of 90 g / m². 2 The overall thickness is 0.597mm.

[0211] Comparative Example 4

[0212] (1) Prepare an alkaline solution of 25 g / L using potassium hydroxide (KOH) and allow it to cool to room temperature. Add coarse denier polyimide fibers (2.2 dtex × 60 mm, trilobal cross-section) to the alkaline solution at a bath ratio of 1:10, soak for 30 minutes, remove and dehydrate. Rinse the fiber surface with clean water to remove excess alkaline substances. The washing acceptance standard is that the pH value of the aqueous solution after soaking the fiber for 20 minutes is close to 7.0. Dehydrate until there is no free water to obtain intermediate state fibers.

[0213] Prepare a 6 g / L acidic solution using glacial acetic acid (CH3COOH). Add the intermediate-state fibers to the acidic solution at a bath ratio of 1:10, soak for 20 minutes, then remove and dehydrate. Rinse the fiber surface with clean water to remove excess alkaline substances. The washing acceptance standard is that the pH value of the aqueous solution after 20 minutes of fiber soaking is close to 7.0. Dehydrate until no free water remains, and dry the fibers at 80℃ to constant weight to obtain surface-modified coarse denier polyimide fibers.

[0214] (2) The fine denier polyimide fiber (1.22 tex × 38 mm, trilobal cross section) is subjected to the surface modification treatment of step (1) to obtain the surface-modified fine denier polyimide fiber.

[0215] (3) Weigh 160 kg of surface-modified coarse denier polyimide fiber (2.2 dtex × 60 mm, trilobal cross section) and 240 kg of pure cotton fiber (white cotton grade 2, length 27 mm, main micronaire value grade B) respectively.

[0216] The surface-modified coarse denier polyimide fibers and pure cotton fibers are weighed and opened separately. The opened fibers are fed into the fiber bin to fully mix the two types of fibers. The mixed fibers are then formed into a uniform fiber web. The fiber web then enters the carding process, which uses a two-carding-one-laying production line. The fiber webs output from the two carding machines are simultaneously fed to a cross-laying machine to lay the web and obtain a uniform upper layer fiber web.

[0217] (4) Weigh out 90 kg of surface-modified fine denier polyimide fiber (1.22 dtex × 38 mm, trilobal cross section), 90 kg of pure cotton fiber (white cotton grade 2, length 27 mm, main micronaire value grade B) and 120 kg of fine denier viscose fiber (0.9 dtex × 38 mm).

[0218] The surface-modified fine denier polyimide fibers, pure cotton fibers, and fine denier viscose fibers are weighed and opened separately. The opened fibers are then fed into a fiber bin to fully mix the three types of fibers. The mixed fibers are then formed into a uniform fiber web. The web then enters the carding process, which uses a two-carding-one-laying production line. The fiber webs output from two carding machines are simultaneously fed to a cross-laying machine to lay the web and obtain a uniform middle layer fiber web.

[0219] (5) Weigh 300 kg of fine denier viscose fiber (0.9 dtex × 38 mm).

[0220] The weighed viscose fibers are opened and fed into a fiber bin. After thorough mixing, the mixed fibers are formed into a uniform fiber web. The web then enters the carding process, which uses a two-carding-one-laying production line. The fiber webs output from two carding machines are simultaneously fed to a cross-laying machine to lay the web and obtain a uniform lower layer.

[0221] (6) The upper uniform fiber web, the middle uniform fiber web and the lower uniform fiber web are placed from top to bottom and subjected to a 120°C hot rolling process to complete the initial composite process, and a three-layer fiber web composite material is obtained.

[0222] The three-layer fiber web composite material is fed to a pre-needling machine and a reverse needle punching machine for pre-needling and reverse needle punching to entangle and shape the fiber web material and obtain an intermediate nonwoven fabric.

[0223] The obtained intermediate nonwoven fabric is dried and surface calendered by a hot rolling process at 120℃, and then dried at 100℃ to obtain the nonwoven fabric (final product) used for the atomizing core.

[0224] The nonwoven fabric (final product) prepared above has an overall basis weight of 90 g / m². 2 The overall thickness is 1.125mm.

[0225] Comparative Example 5

[0226] (1) Weigh out 160 kg of coarse denier polyimide fiber (2.2 dtex × 60 mm, trilobal cross section) and 240 kg of pure cotton fiber (white cotton grade 2, length 27 mm, main micronaire value grade B).

[0227] The weighed coarse denier polyimide fibers and pure cotton fibers are opened separately. The opened fibers are then fed into a fiber bin to fully mix the two types of fibers. The mixed fibers are then formed into a uniform fiber web. The web then enters the carding process, which uses a two-carding-one-laying production line. The fiber webs output from the two carding machines are simultaneously fed to a cross-laying machine to lay the web and obtain a uniform upper layer fiber web.

[0228] (2) Weigh out 90 kg of fine denier polyimide fiber (1.22 dtex × 38 mm, trilobal cross section), 90 kg of pure cotton fiber (white cotton grade 2, length 27 mm, main micronaire value grade B) and 120 kg of fine denier viscose fiber (0.9 dtex × 38 mm).

[0229] Fine denier polyimide fiber, pure cotton fiber, and fine denier viscose fiber are weighed and opened separately. The opened fibers are then fed into a fiber bin to fully mix the three types of fibers. The mixed fibers are then formed into a uniform fiber web. The web then enters the carding process, which uses a two-carding-one-layout production line. The fiber webs output from two carding machines are simultaneously fed to a cross-layout machine to lay the web and obtain a uniform middle layer fiber web.

[0230] (3) Weigh 300 kg of fine denier viscose fiber (0.9 dtex × 38 mm).

[0231] The weighed viscose fibers are opened and fed into a fiber bin. After thorough mixing, the mixed fibers are formed into a uniform fiber web. The web then enters the carding process, which uses a two-carding-one-laying production line. The fiber webs output from two carding machines are simultaneously fed to a cross-laying machine to lay the web and obtain a uniform lower layer.

[0232] (4) The upper uniform fiber web, the middle uniform fiber web and the lower uniform fiber web are placed from top to bottom and subjected to a 120°C hot rolling process to complete the initial composite process, and a three-layer fiber web composite material is obtained.

[0233] The three-layer fiber web composite material is fed into a hydroentangling machine for pre-punching treatment. The pre-punching water pressure is 5 bar. The pre-punched uniform fiber web is hydroentangled seven times in both directions, four times in the forward direction and three times in the reverse direction (forward-reverse-forward-reverse-forward-reverse-forward). The hydroentangling pressures are 20 bar, 20 bar, 30 bar, 30 bar, 35 bar, 35 bar, and 35 bar, respectively. The spraying time is controlled at 2 minutes, and the production line speed is 35 meters per minute. After that, it is dried at 120°C to obtain an intermediate nonwoven fabric.

[0234] The obtained intermediate nonwoven fabric is dried and surface calendered by a hot rolling process at 120℃, and then dried at 100℃ to obtain the nonwoven fabric (final product) used for the atomizing core.

[0235] The nonwoven fabric (final product) prepared above has an overall basis weight of 90 g / m². 2 The overall thickness is 0.615mm.

[0236] Comparative Example 6

[0237] (1) Weigh out 400 kg of pure cotton fiber (white cotton grade 2, length 27 mm, main micronaire value grade B).

[0238] The pure cotton fibers are weighed and opened, then fed into a fiber bin. The mixed fibers are formed into a uniform fiber web. The process then proceeds to the carding stage, which uses a two-carding-one-laying production line. The fiber webs output from two carding machines are simultaneously fed to a cross-laying machine to form a uniform upper layer fiber web.

[0239] (2) Weigh out 150 kg of pure cotton fiber (white cotton grade 2, length 27 mm, main micron value grade B) and 150 kg of fine denier viscose fiber (0.9 dtex × 38 mm).

[0240] Pure cotton fibers and fine denier viscose fibers are weighed and opened separately. The opened fibers are then fed into a fiber bin to fully mix the two types of fibers. The mixed fibers are then formed into a uniform fiber web. The web then enters the carding process, which uses a two-carding-one-laying production line. The fiber webs output from the two carding machines are simultaneously fed to a cross-laying machine to lay the web and obtain a uniform middle layer fiber web.

[0241] (3) Weigh 300 kg of fine denier viscose fiber (0.9 dtex × 38 mm).

[0242] The weighed viscose fibers are opened and fed into a fiber bin. After thorough mixing, the mixed fibers are formed into a uniform fiber web. The web then enters the carding process, which uses a two-carding-one-laying production line. The fiber webs output from two carding machines are simultaneously fed to a cross-laying machine to lay the web and obtain a uniform lower layer.

[0243] (4) The upper uniform fiber web, the middle uniform fiber web and the lower uniform fiber web are placed from top to bottom and subjected to a 120°C hot rolling process to complete the initial composite process, and a three-layer fiber web composite material is obtained.

[0244] The three-layer fiber web composite material is fed into a hydroentangling machine for pre-punching treatment. The pre-punching water pressure is 5 bar. The pre-punched uniform fiber web is hydroentangled seven times in both directions, four times in the forward direction and three times in the reverse direction (forward-reverse-forward-reverse-forward-reverse-forward). The hydroentangling pressures are 20 bar, 20 bar, 30 bar, 30 bar, 35 bar, 35 bar, and 35 bar, respectively. The spraying time is controlled at 2 minutes, and the production line speed is 35 meters per minute. After that, it is dried at 120°C to obtain an intermediate nonwoven fabric.

[0245] The obtained intermediate nonwoven fabric is dried and surface calendered by a hot rolling process at 120℃, and then dried at 100℃ to obtain the nonwoven fabric (final product) used for the atomizing core.

[0246] The nonwoven fabric (final product) prepared above has an overall basis weight of 90 g / m². 2 The overall thickness is 0.493mm.

[0247] Comparative Example 7

[0248] (1) Prepare an alkaline solution of 25 g / L using potassium hydroxide (KOH) and allow it to cool to room temperature. Add coarse denier polyimide fibers (2.2 dtex × 60 mm, trilobal cross-section) to the alkaline solution at a bath ratio of 1:10, soak for 30 minutes, remove and dehydrate. Rinse the fiber surface with clean water to remove excess alkaline substances. The washing acceptance standard is that the pH value of the aqueous solution after soaking the fiber for 20 minutes is close to 7.0. Dehydrate until there is no free water to obtain intermediate state fibers.

[0249] Prepare a 6 g / L acidic solution using glacial acetic acid (CH3COOH). Add the intermediate-state fibers to the acidic solution at a bath ratio of 1:10, soak for 20 minutes, then remove and dehydrate. Rinse the fiber surface with clean water to remove excess alkaline substances. The washing acceptance standard is that the pH value of the aqueous solution after 20 minutes of fiber soaking is close to 7.0. Dehydrate until no free water remains, and dry the fibers at 80℃ to constant weight to obtain surface-modified coarse denier polyimide fibers.

[0250] (2) The fine denier polyimide fiber (1.22 tex × 38 mm, trilobal cross section) is subjected to the surface modification treatment of step (1) to obtain the surface-modified fine denier polyimide fiber.

[0251] (3) Weigh 400 kg of surface-modified coarse denier polyimide fiber (2.2 dtex × 60 mm, trilobal cross section).

[0252] The surface-modified coarse denier polyimide fibers are weighed and opened. The opened fibers are then fed into a fiber bin, and the mixed fibers are formed into a uniform fiber web. The fiber web then enters the carding process, which uses a two-carding-one-laying production line. The fiber webs output from the two carding machines are simultaneously fed to a cross-laying machine to lay the web and obtain a uniform upper layer fiber web.

[0253] (4) Weigh 300 kg of surface-modified fine denier polyimide fiber (1.22 dtex × 38 mm, trilobal cross section).

[0254] The surface-modified fine denier polyimide fibers are weighed and opened. The opened fibers are then fed into a fiber bin, and the mixed fibers are formed into a uniform fiber web. The fiber web then enters the carding process, which uses a two-carding-one-layout production line. The fiber webs output from two carding machines are simultaneously fed to a cross-layout machine to lay the web and obtain a uniform middle layer fiber web.

[0255] (5) Weigh 300 kg of fine denier viscose fiber (0.9 dtex × 38 mm).

[0256] The weighed viscose fibers are opened and fed into a fiber bin. After thorough mixing, the mixed fibers are formed into a uniform fiber web. The web then enters the carding process, which uses a two-carding-one-laying production line. The fiber webs output from two carding machines are simultaneously fed to a cross-laying machine to lay the web and obtain a uniform lower layer.

[0257] (6) The upper uniform fiber web, the middle uniform fiber web and the lower uniform fiber web are placed from top to bottom and subjected to a 120°C hot rolling process to complete the initial composite process, and a three-layer fiber web composite material is obtained.

[0258] The three-layer fiber web composite material is fed into a hydroentangling machine for pre-punching treatment. The pre-punching water pressure is 5 bar. The pre-punched uniform fiber web is hydroentangled seven times in both directions, four times in the forward direction and three times in the reverse direction (forward-reverse-forward-reverse-forward-reverse-forward). The hydroentangling pressures are 20 bar, 20 bar, 30 bar, 30 bar, 35 bar, 35 bar, and 35 bar, respectively. The spraying time is controlled at 2 minutes, and the production line speed is 35 meters per minute. After that, it is dried at 120°C to obtain an intermediate nonwoven fabric.

[0259] The obtained intermediate nonwoven fabric is dried and surface calendered by a hot rolling process at 120℃, and then dried at 100℃ to obtain the nonwoven fabric (final product) used for the atomizing core.

[0260] The nonwoven fabric (final product) prepared above has an overall basis weight of 90 g / m². 2 The overall thickness is 0.677mm.

[0261] Test Results

[0262] Table 1 shows the test data of the nonwoven fabrics prepared in Examples 1-3 and Comparative Examples 1-7 in terms of properties such as basis weight, thickness, oil conductivity, oil storage capacity, and lifespan.

[0263] Table 1

[0264]

[0265]

[0266] As can be seen from the test data of Examples 1-3 and Comparative Examples 1-3 in Table 1, the nonwoven fabric prepared in this application has both high oil storage and oil conductivity and a long service life. This shows that the nonwoven fabric composed of three fiber layers in this application can take into account both oil conductivity and service life.

[0267] Based on the comparison of the test data of Examples 1-3 and Comparative Example 4 in Table 1, it can be seen that, under similar basis weights, the thickness of the nonwoven fabrics prepared in Examples 1-3 is significantly lower than that in Comparative Example 1, and they have better oil-conducting performance and service life.

[0268] Based on the comparison of test data from Examples 1-3 and Comparative Example 5 in Table 1, it can be seen that by performing surface modification treatment on the first polyimide fiber of the upper fiber layer and the second polyimide fiber of the middle fiber layer, the oil-conducting performance and service life of the prepared nonwoven fabric can be improved.

[0269] Based on the comparison of the test data of Examples 1-3 and Comparative Example 6 in Table 1, it can be seen that the upper fiber layer of Comparative Example 6 did not have the first polyimide fiber added, and the middle fiber layer did not have the second polyimide fiber added. Under the same basis weight, the thickness, oil conductivity, oil storage and service life of the nonwoven fabric prepared by Comparative Example 6 were all lower than those of Examples 1-3.

[0270] Based on the comparison of the test data of Examples 1-3 and Comparative Example 7 in Table 1, it can be seen that the upper layer fiber of Comparative Example 7 did not contain pure cotton fiber, and the middle layer fiber did not contain pure cotton fiber or viscose fiber. The oil conductivity and oil storage properties of the nonwoven fabric prepared by Comparative Example 7 were significantly reduced, and the atomizing core life of the nonwoven fabric of Comparative Example 7 was very short. This shows that using only heat-resistant fiber will seriously weaken the oil conductivity. Insufficient oil conductivity can easily lead to dry burning and scorching of the core, resulting in a shorter atomizing core life.

[0271] Furthermore, based on the data in Table 1, it can be seen that the lifespan of the nonwoven fabric prepared in this application is not directly linearly related to any single property of the nonwoven fabric, such as its basis weight, thickness, oil conductivity, oil storage capacity, or structure. Therefore, the technical solution of this application, through improvements in composition and process, enables the nonwoven fabric to balance lifespan and these individual properties; without changing certain properties, it enables the nonwoven fabric to have a longer service life in the application scenario of atomizing core.

[0272] The nonwoven fabric for atomizing core and its preparation method provided in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A nonwoven fabric for an atomizing core, characterized by: The non-woven fabric comprises a lower fiber layer, a middle fiber layer and an upper fiber layer arranged in a stack; The upper fiber layer comprises the following components in mass fraction: 30-40 parts of first polyimide fiber, and 60-70 parts of pure cotton fiber; The middle fiber layer comprises the following components in mass fraction: 10-50 parts of second polyimide fiber, 20-40 parts of pure cotton fiber, and 30-50 parts of viscose fiber; The lower fiber layer comprises the following components in mass fraction: 100 parts of viscose fiber; The fineness of the first polyimide fiber is greater than that of the second polyimide fiber; The upper fiber layer is arranged to contact the high-temperature heating side of the heating body of the atomizing core; The fineness of the first polyimide fiber ranges from 2.2 dtex to 6.0 dtex, the fineness of the second polyimide fiber ranges from 0.9 dtex to 1.3 dtex, the fineness of the viscose fiber ranges from 0.5 dtex to 3.8 dtex, and the fineness of the pure cotton fiber ranges from 0.5 dtex to 3.8 dtex; The thickness ratio of the upper fiber layer ranges from 40% to 50%, the thickness ratio of the middle fiber layer ranges from 25% to 30%, and the thickness ratio of the lower fiber layer ranges from 25% to 30%, based on the overall thickness of the non-woven fabric.

2. The non-woven fabric for an atomizing core according to claim 1, characterized in that: The first polyimide fiber is a thick denier polyimide fiber, and the second polyimide fiber is a thin denier polyimide fiber; And / or the first polyimide fiber is a profiled cross-section polyimide fiber, and the second polyimide fiber is a profiled cross-section polyimide fiber.

3. The non-woven fabric for an atomizing core according to claim 1, characterized in that: The first polyimide fiber is obtained by surface modification treatment of a first fiber raw material, and / or the second polyimide fiber is obtained by surface modification treatment of a second fiber raw material; The first fiber raw material is a thick denier polyimide fiber, and the second fiber raw material is a thin denier polyimide fiber; And / or the first fiber raw material is a profiled cross-section polyimide fiber, and the second fiber raw material is a profiled cross-section polyimide fiber.

4. The non-woven fabric for an atomizing core according to claim 1, characterized in that: The viscose fiber is a thin denier viscose fiber.

5. The non-woven fabric for an atomizing core according to claim 1, characterized in that: The length of the first polyimide fiber ranges from 38 mm to 60 mm, the length of the second polyimide fiber ranges from 38 mm to 60 mm, the length of the viscose fiber ranges from 18 mm to 60 mm, and the length of the pure cotton fiber ranges from 18 mm to 38 mm.

6. The non-woven fabric for an atomizing core according to claim 1, characterized in that: The mass ratio of the upper fiber layer ranges from 20% to 40%, the mass ratio of the middle fiber layer ranges from 20% to 40%, and the mass ratio of the lower fiber layer ranges from 20% to 40%, based on the overall mass of the non-woven fabric. The porosity of the upper fiber layer is in the range of 85% to 95%, the porosity of the middle fiber layer is in the range of 80% to 90%, and the porosity of the lower fiber layer is in the range of 75% to 85%. 7.The non-woven fabric for an atomizing core according to any one of claims 1 to 6, characterized in that: The overall mass of the nonwoven fabric for the atomizing core ranges from 60 to 150 g / m 2 The overall thickness of the nonwoven fabric for the atomizing core ranges from 0.4 to 1.2 mm.

8. A method of producing the nonwoven fabric for an atomizing core according to any one of claims 1 to 7, characterized by: comprising the following steps: Take the first polyimide fiber, pure cotton fiber, and mix them according to the proportion, and carry out carding and laying to obtain an upper uniform fiber web; Take the second polyimide fiber, pure cotton fiber, and viscose fiber, and mix them according to the proportion, and carry out carding and laying to obtain a middle uniform fiber web; Take the viscose fiber, and carry out carding and laying to obtain a lower uniform fiber web; The whole of the upper uniform fiber web, the middle uniform fiber web, and the lower uniform fiber web is reinforced to obtain the non-woven fabric for an atomizing core. 9.The preparation method according to claim 8, characterized in that: The reinforcing of the whole of the upper uniform fiber web, the middle uniform fiber web, and the lower uniform fiber web comprises the following steps: Place the upper uniform fiber web, the middle uniform fiber web, and the lower uniform fiber web in order from top to bottom, and complete preliminary compounding by hot rolling to obtain a three-layer fiber web composite material; Pre-punch the three-layer fiber web composite material; Multi-pass forward and reverse hydroentangle the three-layer fiber web composite material after pre-punching, and dry to obtain the non-woven fabric; The pre-punching pressure is in the range of 1-10 bar, the hydroentangle pressure of the multi-pass forward and reverse hydroentangle is in the range of 20-50 bar, the hydroentangle pressure gradually increases, the spraying time of the forward and reverse hydroentangle is 0.5-15 min, and the linear speed of the forward and reverse hydroentangle is in the range of 30-100 m / min.

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