A method for preparing a highly breathable, flushable, leak-proof layer and its application in absorbent sanitary products

Abstract

The present invention relates to the field of disposable absorbent sanitary products, and discloses a method for preparing a highly breathable, flushable, and leak-proof layer and its application in absorbent sanitary products. The preparation method comprises the following steps: forming a web of ultrashort fibers, and then entangle the ultrashort fibers with each other to form reinforced surface sheets and bottom sheets, respectively; placing water-repellent fibers between the surface sheets and the bottom sheets to form a loose water-repellent fiber layer; connecting the periphery of the bottom sheet with the periphery of the surface sheet at the top and bottom to wrap and fix the water-repellent fiber layer to form a highly breathable, and flushable, leak-proof layer. The present invention adopts a method of forming a web of ultrashort fibers and entanglement and reinforcement to prepare the surface sheets and the bottom sheets, adopts water-repellent fibers to prepare a water-repellent fiber layer that is not entangled and reinforced, and overlaps the three layers in a specific order so that they can cooperate with each other to give the leak-proof layer better liquid isolation, flushability, air permeability, and structural strength.

Description

Technical Field

[0001] The invention relates to the field of disposable absorbent sanitary products, in particular to a preparation method of a highly air-permeable dispersible anti-leakage layer and its application in absorbent sanitary products. Background Art

[0002] Disposable absorbent sanitary products refer to sanitary products that are in direct contact with human skin and are used once for the purpose of physiological hygiene or health care. They mainly include female sanitary products (such as sanitary napkins and panty liners), baby diapers (such as baby diapers / pads) and adult incontinence products (such as adult diapers / pads). Due to their good liquid absorption and retention, as well as their cleanliness, hygiene and ease of use, they are widely used in daily life. However, how to deal with these disposable absorbent sanitary products after use has become an important issue that troubles consumers and even the entire society.

[0003] The use of degradable materials can achieve the natural degradation of disposable absorbent sanitary products, but it still cannot solve the problem that they cannot be directly flushed into the toilet after use, making these disposable absorbent sanitary products inconvenient to handle after use. After being discarded, they can only be incinerated or landfilled for natural degradation, which is prone to bacterial breeding, mosquito gathering and other problems, and also brings serious harm to the environment. Therefore, the development of flushable disposable absorbent sanitary products has become a hot topic in the industry.

[0004] The structure of disposable absorbent sanitary products is usually composed of a surface layer, an absorbent layer and a leakproof layer, among which the leakproof layer plays a key role in preventing liquid leakage. However, in the development process of flushable disposable absorbent sanitary products, there is a contradiction between the flushability, liquid barrier and air permeability of the leakproof layer. For example, in the patent with publication number CN113395952A, polyvinyl alcohol film is used as the material of the leakproof layer, so that the leakproof layer can be dispersed or dissolved in water, but the liquid barrier and air permeability of the polyethylene film are poor.

[0005] In view of the above problems existing in the prior art, it is necessary to develop a new type of leak-proof layer that can meet the requirements of liquid isolation and flushability and has excellent air permeability to meet the development needs of flushable disposable absorbent sanitary products. Summary of the invention

[0006] In order to solve the technical problem that the existing leakproof layer is difficult to take into account the flushability, liquid isolation and air permeability, the present invention provides a preparation method of a highly air-permeable flushable leakproof layer and its application in absorbent sanitary products. In the preparation method, a surface sheet, a bottom sheet and a water-repellent fiber layer are prepared by a specific method, and the three layers are stacked in a specific order so that they can cooperate with each other, so that the obtained leakproof layer has good liquid isolation, flushability and air permeability, and also has high structural strength.

[0007] The specific technical scheme of the present invention is:

[0008] In a first aspect, the present invention provides a method for preparing a highly air-permeable dispersible anti-leakage layer, comprising the following steps:

[0009] (1) forming a web of ultrashort fibers, and then entangle the ultrashort fibers with each other to form a reinforced surface sheet and a bottom sheet respectively; (2) placing water-repellent fibers between the surface sheet and the bottom sheet to form a loose water-repellent fiber layer;

[0010] (3) The periphery of the bottom sheet is connected to the periphery of the surface sheet at the top and bottom, so that the water-repellent fiber layer is covered and fixed to form a highly breathable and dispersible leak-proof layer.

[0011] In the above preparation process, the water-repellent fiber layer is made of water-repellent fibers, which have a lower surface energy and are not easily wetted by liquids, thus giving the leak-proof layer better liquid isolation. However, water repellency will hinder the water dispersion of the leak-proof layer after use. Therefore, when preparing the water-repellent fiber layer, the present invention does not entangle and reinforce it, so the fibers therein are loosely distributed, which can solve the problem of decreased water dispersion caused by improved water repellency.

[0012] In addition, the surface sheet and the bottom sheet are prepared by using ultra-short fibers to form a web and entangle the ultra-short fibers with each other. The entangled fibers can give them higher strength. By wrapping and fixing the loose and fluffy water-repellent fiber layer between the surface layer and the bottom layer, the structural strength of the leak-proof layer can be improved to meet the use requirements of sanitary products. However, the entanglement of the fibers will hinder the water dispersibility of the leak-proof layer after use. Therefore, the present invention uses ultra-short fibers as materials to prepare the surface sheet and the bottom sheet, which can meet the requirements of flushability. Moreover, after the surface layer and the bottom layer are dispersed and disintegrated, the fixing effect on the water-repellent fiber layer is lost, so that the water-repellent fiber layer is easy to disperse and disintegrate under the action of water flow.

[0013] In addition, in the present invention, the surface sheet, the bottom sheet and the water-repellent fiber layer are all composed of fibers, and the obtained leakage-proof layer does not contain a polymer film, so it has good air permeability and can solve the problem of poor air permeability and poor comfort of the leakage-proof layer of existing disposable absorbent sanitary products.

[0014] In summary, the present invention adopts different methods to prepare the surface sheet, the bottom sheet and the water-repellent fiber layer, and stacks the three in a specific order, so that the obtained leak-proof layer has good liquid isolation, flushability and air permeability, while ensuring that it has high structural strength.

[0015] Preferably, the ultrashort fibers in step (1) and the water-repellent fibers in step (2) are both degradable fibers.

[0016] In the present invention, the fiber materials of the surface layer, the water-repellent fiber layer and the bottom layer can be made of degradable fibers, so that the leak-proof layer can be naturally degraded after use, thereby reducing pollution to the environment.

[0017] Preferably, the specific process of step (2) includes the following steps: air-laying the water-repellent fibers into a water-repellent fiber web, and then placing the water-repellent fiber web between the surface sheet and the bottom sheet to form a loose water-repellent fiber layer.

[0018] Preferably, the specific process of step (2) includes the following steps: evenly spreading the water-repellent fibers on the bottom sheet to form a loose water-repellent fiber layer, and then laminating the surface sheet onto the water-repellent fiber layer.

[0019] Preferably, the specific process of step (2) includes the following steps: placing water-repellent fibers on a bottom sheet to form a loose water-repellent fiber layer, and then applying water-absorbing and swelling polymer powder to the upper surface of the water-repellent fiber layer to form a water-absorbing and swelling polymer powder layer, and then laminating the surface sheet onto the water-absorbing and swelling polymer powder layer.

[0020] When the leak-proof layer is used, after the liquid passes through the surface layer and comes into contact with the water-absorbing and swelling polymer powder layer, the water-absorbing and swelling polymer powder absorbs the liquid and can play a certain role in blocking water; moreover, the water-absorbing and swelling polymer powder will swell before dissolving. As time goes by, the powders will combine with each other to form a strong and moist film around them, thereby fixing the liquid and preventing the liquid from seeping in quickly. In addition, after the leak-proof layer is used, the water-absorbing and swelling polymer powder layer will dissolve after coming into contact with more water in the toilet, so it will not affect the flushability of the leak-proof layer.

[0021] Furthermore, the water-absorbing and swelling polymer powder is applied to the upper surface of the water-repellent fiber layer by means of powdering or electrostatic spraying.

[0022] Furthermore, the water-absorbing and swelling polymer powder includes water-absorbing biomass material powder.

[0023] The water-absorbent biomass material powder has good water absorption and swelling properties, which is beneficial to improving the performance of the leak-proof layer in blocking liquids. It is also degradable and can avoid environmental pollution.

[0024] Furthermore, the water-absorbing biomass material powder includes one or more combinations of cellulose-based material powder, chitin-based material powder, starch-based material powder and alginate-based material powder.

[0025] Furthermore, the water-absorbing biomass material powder includes one or more combinations of carboxymethyl cellulose powder, modified starch powder, deacetylated chitosan powder and sodium alginate powder.

[0026] Furthermore, the mass per unit area of ​​the water-swellable polymer powder layer is 20 to 200 g / m 2 .

[0027] Preferably, in step (1), the surface sheet is a hydrophilic material.

[0028] The use of a hydrophilic surface layer enables the leak-proof layer to diffuse downward and around simultaneously along the surface layer when liquid contacts the surface layer during use, thereby avoiding local penetration caused by the concentration of seeping liquid.

[0029] Preferably, in step (1), the bottom sheet is a hydrophobic material.

[0030] In the water-repellent fiber layer, loose fibers are easy to move and the porosity between the fibers is high. Therefore, the present invention arranges a hydrophobic bottom layer under the water-repellent fiber layer, which enables the water-repellent fiber layer and the bottom layer with different characteristics to cooperate with each other to form a double-layer barrier, thereby further improving the liquid isolation property of the leak-proof layer.

[0031] Preferably, the water repellency of the bottom sheet in step (1) is less than the water repellency of the water-repellent fiber layer in step (2).

[0032] The research and development team of the present invention has found that the water repellency and flushability of fiber materials are a pair of contradictions, that is, the improvement of the water repellency index of fiber materials will affect the flushability of the materials. To this end, the present invention adopts a double-layer composite structure of a water-repellent fiber layer and a bottom layer, and designs the water repellency of the former to be greater than the latter, which can produce the following effects: the fibers in the bottom layer are entangled with each other, so in order to ensure that the water flow can better penetrate into the leak-proof layer through the bottom layer after use to disperse and disintegrate it, the water repellency of the bottom layer should not be too large; the fibers in the water-repellent fiber layer are loosely distributed and easy to disperse and disintegrate, so under the premise of ensuring good flushability, the water-repellent fiber layer can be set to a relatively high water repellency. In the above manner, the bottom layer with entangled fibers and relatively low water repellency cooperates with the water-repellent fiber layer with loosely distributed fibers and relatively high water repellency, so that the leak-proof layer can have both good flushability and liquid isolation.

[0033] Furthermore, the droplet contact angle of the water-repellent fiber layer in step (2) is ≥130°, and the droplet contact angle of the bottom sheet in step (1) is 90-120°.

[0034] By controlling the droplet contact angles of the water-repellent fiber layer and the bottom sheet material within the above ranges, the liquid barrier property and flushability of the leak-proof layer can be better balanced.

[0035] Preferably, in step (1), part or all of the ultrashort fibers used to prepare the surface sheet are fibers with special-shaped cross-sections.

[0036] The special-shaped cross-section fiber has a larger specific surface area, which can accelerate the diffusion of liquid. Therefore, for the hydrophilic surface layer, the use of special-shaped cross-section fibers in the surface layer is conducive to the diffusion of liquid along the surface layer to the surrounding areas, thereby better avoiding the concentration of infiltrating liquid and causing local penetration. In addition, compared with ordinary circular cross-section fibers, the pores between the special-shaped cross-section fibers after entanglement are larger, and they are very easy to disperse under the impact of high-pressure water flow, thereby further improving the dispersibility of the anti-leakage layer.

[0037] Furthermore, the cross-sectional shape of the special-shaped cross-sectional fiber is trilobal or triangular.

[0038] Preferably, in step (2), the length of the water-repellent fiber is 0.5 to 20 mm, more preferably 2 to 5 mm.

[0039] Preferably, in step (2), the volume density of the water-repellent fiber layer is 50 to 120 kg / m 3 , unit area mass is 30~200g / m 2 .

[0040] By controlling the volume density and mass per unit area of ​​the water-repellent fiber layer within a certain range, the pore diameter between the water-repellent fibers can be made smaller than the diameter of the water droplets, so that the surface energy of the water-repellent fiber layer is low and the liquid cannot wet it, thereby improving the liquid barrier properties of the leak-proof layer.

[0041] Preferably, in step (1), the volume density of the surface sheet is 60 to 350 kg / m 3 , unit area mass is 20~100g / m 2 .

[0042] Preferably, in step (1), the bulk density of the bottom sheet is 60 to 350 kg / m 3 , mass per unit area is 20~100g / m 2 .

[0043] Preferably, the specific process of step (1) comprises the following steps:

[0044] (1.1) forming a net of hydrophilic ultrashort fibers, and then entangle and reinforce the fibers to form a surface sheet;

[0045] (1.2) Ultra-short hydrophobic fibers, or a mixture of ultra-short hydrophobic fibers and ultra-short hydrophilic fibers, are formed into a web, and the fibers are entangled and reinforced to form a bottom sheet.

[0046] Furthermore, the hydrophilic ultrashort fibers in step (1.1) and the ultrashort hydrophilic fibers in step (1.2) are independently selected from one or more combinations of biomass virgin fibers, biomass recycled fibers, and plant pulp fibers.

[0047] Furthermore, the hydrophilic ultrashort fibers described in step (1.1) and the ultrashort hydrophilic fibers described in step (1.2) are independently selected from one or more combinations of viscose fibers, tencel fibers, cotton fibers, bamboo pulp fibers, chitosan fibers, wood pulp fibers, and cotton pulp fibers.

[0048] Preferably, in step (1), the web forming method is wet web forming or dry web forming. Preferably, in step (3), the method of connecting the periphery of the bottom sheet with the periphery of the surface sheet at the top and bottom is ultrasonic bonding, adhesive bonding, hot rolling bonding or sewing.

[0049] In a second aspect, the present invention provides a highly air-permeable, dispersible, leak-proof layer produced by the preparation method.

[0050] Preferably, the highly breathable and dispersible leak-proof layer comprises, from top to bottom, a surface layer, a water-repellent fiber layer and a bottom layer; the surface layer and the bottom layer are both aggregates of mutually entangled ultra-short fibers; the water-repellent fiber layer is a loose aggregate of water-repellent fibers; the water-repellent fiber layer is wrapped and fixed on all sides by the surface layer and the bottom layer.

[0051] Preferably, the surface layer is a hydrophilic aggregate composed of mutually entangled ultra-short fibers; and the bottom layer is a hydrophobic aggregate composed of mutually entangled ultra-short fibers.

[0052] Preferably, the water repellency of the water repellent fiber layer is greater than that of the base layer.

[0053] Furthermore, the droplet contact angle of the water-repellent fiber layer is ≥130°, and the droplet contact angle of the bottom layer is 90-120°.

[0054] Preferably, a water-absorbing and swelling polymer powder layer is provided between the surface layer and the water-repellent fiber layer; the water-absorbing and swelling polymer powder layer is composed of water-absorbing and swelling polymer powder.

[0055] In a third aspect, the present invention provides the use of the highly air-permeable, flushable, anti-leakage layer in absorbent sanitary products.

[0056] Preferably, the absorbent sanitary product comprises, from top to bottom, a flushable surface layer, a flushable absorbent layer and the highly breathable flushable leak-proof layer; the upper surface of the surface layer is in contact with the lower surface of the flushable absorbent layer; the periphery of the flushable surface layer is connected to the periphery of the leak-proof layer; and the flushable absorbent layer is covered and fixed on all sides by the flushable surface layer and the leak-proof layer.

[0057] Compared with the prior art, the present invention has the following advantages:

[0058] (1) In the process of preparing the leakproof layer, the present invention adopts the method of forming a web of ultra-short fibers and reinforcing fibers by entanglement to prepare the surface sheet and the bottom sheet, adopts the water-repellent fiber to prepare the water-repellent fiber layer which is not entangled and reinforced, and stacks the three layers in a specific order, so that they can cooperate with each other and give the leakproof layer better liquid isolation, dispersibility, air permeability and structural strength;

[0059] (2) In the process of preparing the leakproof layer, the present invention applies water-absorbing and swelling polymer powder on the upper surface of the water-repellent fiber, and can utilize the water-absorbing and swelling characteristics of the powder to slow down the infiltration of liquid, thereby further improving the liquid barrier property of the leakproof layer;

[0060] (3) In the process of preparing the leakproof layer, the present invention uses a hydrophobic bottom sheet with entangled fibers and relatively low water repellency, which is matched with a water-repellent fiber layer with loosely distributed fibers and relatively high water repellency, so that the leakproof layer can have both good flushability and liquid isolation properties;

[0061] (4) In the process of preparing the leak-proof layer of the present invention, a hydrophilic surface sheet is used, which can disperse the liquid to the surrounding area and avoid local infiltration caused by the concentration of infiltrated liquid. On this basis, by using special-shaped cross-section fibers to prepare the surface sheet, the effect of dispersing the liquid on the surface can be further improved, and the flushability of the leak-proof layer can also be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 is a schematic diagram of a cross-sectional structure of the dispersible breathable and leakproof layer in Example 1;

[0063] Figure 2 is a schematic diagram of a cross-sectional structure of the dispersible breathable and leakproof layer in Example 2;

[0064] Figure 3 It is a schematic diagram of a cross-sectional structure of a flushable sanitary napkin or panty liner in Example 2.

[0065] The reference numerals in the drawings are: surface layer 1 , water-repellent fiber layer 2 , bottom layer 3 , water-absorbing and swelling polymer powder layer 4 , flushable absorption layer 5 , and flushable surface layer 6 . DETAILED DESCRIPTION

[0066] The present invention will be further described below in conjunction with the embodiments.

[0067] Overall embodiment

[0068] A kind of permeable and leakproof layer can be dispersed, such as Figure 1 , Figure 2As shown, from top to bottom, it includes a surface layer 1, a water-repellent fiber layer 2 and a bottom layer 3; the surface layer 1 and the bottom layer 3 are both aggregates composed of ultra-short fibers entangled with each other; the water-repellent fiber layer 2 is a loose aggregate composed of water-repellent fibers; the water-repellent fiber layer 2 is wrapped and fixed by the surface layer 1 and the bottom layer 3 on all sides.

[0069] As a specific implementation, the surface layer 1 is a hydrophilic aggregate composed of mutually entangled ultra-short fibers, and the bottom layer 3 is a hydrophobic aggregate composed of mutually entangled ultra-short fibers.

[0070] As a specific embodiment, the water repellency of the water repellent fiber layer 2 is greater than that of the bottom layer 3. Optionally, the droplet contact angle of the water repellent fiber layer 2 is ≥130°, and the droplet contact angle of the bottom layer is 90-120°.

[0071] As a specific implementation, the ultra-short fibers in the surface layer 1 are fibers with a special cross section. Optionally, the cross-sectional shape of the fibers with a special cross section is a trilobal or triangular shape.

[0072] As a specific embodiment, a water-absorbing swelling polymer powder layer 4 is provided between the surface layer 1 and the water-repellent fiber layer 2; the water-absorbing swelling polymer powder layer 4 is composed of water-absorbing swelling polymer powder. Optionally, the water-absorbing swelling polymer powder is a water-absorbing biomass material powder. Further, the water-absorbing biomass material powder is a combination of one or more of cellulose-based material powder, chitin-based material powder, starch-based material powder and alginate-based material powder. Further, the water-absorbing biomass material powder is a combination of one or more of carboxymethyl cellulose (CMC) powder, modified starch powder, deacetylated chitosan powder and sodium alginate powder.

[0073] As a specific embodiment, the volume density of the surface layer 1 is 60 to 350 kg / m 3 , mass per unit area is 20~100g / m 2 The volume density of the water-repellent fiber layer 2 is 50 to 120 kg / m 3 , unit area mass is 30~200g / m 2 The volume density of the bottom layer 3 is 60 to 350 kg / m 3 , mass per unit area is 20~100g / m 2 The mass per unit area of ​​the water-swellable polymer powder layer 4 is 20 to 200 g / m 2 .

[0074] As a specific implementation, the ultrashort fibers and water-repellent fibers are both degradable fibers.

[0075] As a specific implementation, the length of the water-repellent fibers in the water-repellent fiber layer 2 is 0.5 to 20 mm.

[0076] A method for preparing the above-mentioned dispersible breathable and leak-proof layer comprises the following steps:

[0077] (1) forming a web of ultrashort fibers, and then entangle the ultrashort fibers with each other to form a reinforced surface sheet and a bottom sheet respectively; (2) placing water-repellent fibers between the surface sheet and the bottom sheet to form a loose water-repellent fiber layer;

[0078] (3) The periphery of the bottom sheet is connected to the periphery of the surface sheet at the top and bottom, so that the water-repellent fiber layer is covered and fixed to form a highly breathable and dispersible leak-proof layer.

[0079] As a specific implementation, the specific process of step (2) includes the following steps: air-laying the water-repellent fibers into a water-repellent fiber web, and then placing the water-repellent fiber web between the surface sheet and the bottom sheet to form a loose water-repellent fiber layer.

[0080] As another specific implementation, the specific process of step (2) includes the following steps: evenly spreading the water-repellent fibers on the bottom sheet to form a loose water-repellent fiber layer, and then laminating the surface sheet onto the water-repellent fiber layer.

[0081] As a specific embodiment, the specific process of step (2) includes the following steps: placing water-repellent fibers on a bottom sheet to form a loose water-repellent fiber layer, then applying water-absorbing and swelling polymer powder to the upper surface of the water-repellent fiber layer to form a water-absorbing and swelling polymer powder layer, and then laminating the surface sheet on the water-absorbing and swelling polymer powder layer. Optionally, the water-absorbing and swelling polymer powder is applied to the upper surface of the water-repellent fiber layer by dusting or electrostatic spraying. Optionally, the water-absorbing and swelling polymer powder includes water-absorbing biomass material powder.

[0082] As a specific implementation, in step (1), the surface sheet is a hydrophilic material, and the bottom sheet is a hydrophobic material.

[0083] As a specific embodiment, the water repellency of the bottom sheet in step (1) is less than the water repellency of the water repellent fiber layer in step (2). Optionally, the droplet contact angle of the water repellent fiber layer in step (2) is ≥130°, and the droplet contact angle of the bottom sheet in step (1) is 90-120°.

[0084] As a specific implementation, in step (1), part or all of the ultrashort fibers used to prepare the surface sheet are fibers with a special cross section. Optionally, the cross-sectional shape of the special cross-sectional fibers is trilobal or triangular.

[0085] As a specific implementation, the specific process of step (1) includes the following steps:

[0086] (1.1) The hydrophilic ultrashort fibers are formed into a web, and then the fibers are entangled and reinforced to form a surface sheet;

[0087] (1.2) Ultra-short hydrophobic fibers, or a mixture of ultra-short hydrophobic fibers and ultra-short hydrophilic fibers, are formed into a web, and the fibers are entangled and reinforced to form a bottom sheet.

[0088] Optionally, the hydrophilic ultra-short fibers in step (1.1) and the ultra-short hydrophilic fibers in step (1.2) are independently selected from one or more combinations of biomass virgin fibers, biomass recycled fibers, and plant pulp fibers. Further, the hydrophilic ultra-short fibers in step (1.1) and the ultra-short hydrophilic fibers in step (1.2) are independently selected from one or more combinations of viscose fibers, tencel fibers, cotton fibers, bamboo pulp fibers, chitosan fibers, wood pulp fibers, and cotton pulp fibers.

[0089] As a specific implementation, in step (1), the web forming method is wet web forming or dry web forming.

[0090] As a specific implementation, in step (3), the method of connecting the periphery of the bottom sheet with the periphery of the surface sheet at the top and bottom is ultrasonic bonding, adhesive bonding, hot rolling bonding or sewing.

[0091] A disposable absorbent sanitary product, such as Figure 3 As shown, it includes the above-mentioned anti-leakage layer.

[0092] As a specific implementation, a dispersed absorbent layer 5 is provided above the leak-proof layer, and a dispersed surface layer 6 is provided above the dispersed absorbent layer 5; the upper surface of the surface layer 1 is in contact with the lower surface of the dispersed absorbent layer 5; the periphery of the dispersed surface layer 6 is connected to the periphery of the leak-proof layer; the dispersed absorbent layer 5 is covered and fixed by the dispersed surface layer 6 and the leak-proof layer on all sides.

[0093] Example 1

[0094] A kind of permeable and leakproof layer can be dispersed, such as Figure 1 As shown, it is composed of a surface layer 1, a water-repellent fiber layer 2, and a bottom layer 3 connected in sequence from top to bottom. The surface layer 1 and the bottom layer 3 are both composed of mutually entangled ultra-short fibers; the water-repellent fiber layer 2 is a loose water-repellent fiber assembly that is not entangled and reinforced. The water-repellent fiber layer 2 is surrounded and fixed by the surface layer 1 and the bottom layer 3. Each layer can be naturally degraded.

[0095] The volume density of the surface layer 1 is 60 kg / m3 and the mass per unit area is 20 g / m 2The water-repellent fiber layer 2 has a volume density of 50 kg / m 3 , the mass per unit area is 30g / m 2 , made of 100% hydrophobic wood pulp fibers through air-laid processing, with a fiber length of about 2 mm; the droplet contact angle of the water-repellent fiber layer 2 is 130°. The volume density of the bottom layer 3 is 60 kg / m 3 , the mass per unit area is 20g / m 2 It is made by wet papermaking and drying of 50wt% hydrophilic short-cut viscose fibers (fiber specification is 1.67dtex*5mm) and 50wt% ultra-short hydrophobic wood pulp fibers; the droplet contact angle of the bottom layer 3 is 90°.

[0096] The above-mentioned flushable breathable and leak-proof layer is prepared by the following steps:

[0097] (1) 50 wt% hydrophilic short-cut viscose fiber (fiber specification: 1.67 dtex*5 mm) and 50 wt% ultra-short hydrophobic wood pulp fiber were wet-coated and dried to obtain a fiber having a bulk density of 60 kg / m 3 , mass per unit area is 20g / m 2 The bottom sheet;

[0098] (2) Hydrophobic wood pulp fibers with a length of about 2 mm were air-laid to obtain a bulk density of 50 kg / m 3 , mass per unit area is 30g / m 2 The water-repellent fiber layer is superimposed on the bottom sheet;

[0099] (3) The ultra-short wood pulp fibers are wet-coated and dried to obtain a bulk density of 60 kg / m 3 , mass per unit area is 20g / m 2 Surface sheet;

[0100] (4) The surface sheet is superimposed on the water-repellent fiber layer, and the periphery of the surface sheet is bonded to the periphery of the bottom sheet by a hot rolling roller, so that the water-repellent fiber layer is covered and fixed by the surface sheet and the bottom sheet on all sides, thereby obtaining a dispersible breathable and leak-proof layer.

[0101] A dispersible sanitary pad is composed of a dispersible surface layer 6, a dispersible absorption layer 5, and a dispersible breathable and leakproof layer which are sequentially overlapped and connected from top to bottom; each layer is bonded and connected by a water-soluble adhesive. The width of the dispersible surface layer 6 and the dispersible breathable and leakproof layer is greater than that of the dispersible absorption layer 5; the dispersible surface layer 6 is connected to the periphery of the dispersible breathable and leakproof layer to cover and fix the dispersible absorption layer 5. The upper surface of the surface layer 1 in the dispersible breathable and leakproof layer is connected to the lower surface of the dispersible absorption layer 5.

[0102] Among them, the dispersible surface layer 6 is a dispersible non-woven fabric; the dispersible absorption layer 5 is composed of 65% by mass of fluff pulp and 35% of dust-free paper, and is composed of two layers of dust-free paper, the middle of which is fluff pulp, and the three layers are formed by hot rolling and bonding.

[0103] Example 2

[0104] A kind of permeable and leakproof layer can be dispersed, such as Figure 2 As shown, it is composed of a surface layer 1, a solid-liquid layer 4, a water-repellent fiber layer 2, and a bottom layer 3 connected in sequence from top to bottom. The surface layer 1 and the bottom layer 3 are both composed of mutually entangled ultra-short fibers; the solid-liquid layer 4 is composed of water-absorbing and swelling polymer powder; the water-repellent fiber layer 2 is a loose water-repellent fiber assembly that is not entangled and reinforced. The water-repellent fiber layer 2 and the solid-liquid layer are surrounded and fixed by the surface layer 1 and the bottom layer 3. Each layer can be naturally degraded.

[0105] The volume density of the surface layer 1 is 350 kg / m 3 , the mass per unit area is 100g / m 2 The water-repellent fiber layer 2 is made of 30 wt% hydrophilic short-cut viscose fibers (fiber specification is 1.67 dtex*5 mm, cross section is round) and 70 wt% ultra-short wood pulp fibers through wet spunlace processing. The volume density of the water-repellent fiber layer 2 is 120 kg / m 3 , mass per unit area is 200g / m 2 , made of 100% hydrophobic wood pulp fiber through air-laid processing, with a fiber length of about 2mm; the droplet contact angle of the water-repellent fiber layer 2 is 150°. The solid-liquid layer 4 is made of CMC powder through a powdering process, with a unit area mass of 80g / m 2 The volume density of the bottom layer 3 is 350kg / m 3 , the mass per unit area is 100g / m 2 It is made by wet papermaking and drying 30wt% hydrophilic short-cut viscose fibers (fiber specification is 1.67dtex*5mm) and 70wt% ultra-short hydrophobic wood pulp fibers; the droplet contact angle of the bottom layer 3 is 120°.

[0106] The above-mentioned flushable breathable and leak-proof layer is prepared by the following steps:

[0107] (1) 30 wt% hydrophilic short-cut viscose fiber (fiber specification: 1.67 dtex*5 mm) and 70 wt% ultra-short hydrophobic wood pulp fiber were wet-coated and dried to obtain a paper having a bulk density of 350 kg / m 3 , mass per unit area is 100g / m 2 The bottom sheet;

[0108] (2) Hydrophobic wood pulp fibers with a length of about 2 mm were air-laid to obtain a bulk density of 120 kg / m 3, mass per unit area is 200g / m 2 The water-repellent fiber layer is superimposed on the bottom sheet;

[0109] (3) applying CMC powder evenly to the upper surface of the water-repellent fiber layer by dusting to form a water-absorbing and swelling polymer powder layer;

[0110] (4) 30 wt% hydrophilic short-cut viscose fibers (fiber specification: 1.67 dtex*5 mm, cross-section: circular) and 70 wt% ultra-short wood pulp fibers were wet-laid, hydroentangled and dried to obtain a web having a bulk density of 350 kg / m 3 , mass per unit area is 100g / m 2 Surface sheet;

[0111] (4) Overlaying the surface sheet onto the water-absorbing and swelling polymer powder layer, bonding the periphery of the surface sheet to the periphery of the bottom sheet by means of a hot rolling roller, so that the water-repellent fiber layer and the water-absorbing and swelling polymer powder layer are surrounded and fixed by the surface sheet and the bottom sheet, thereby obtaining a dispersible, breathable and leakproof layer.

[0112] A flushable sanitary napkin, such as Figure 3 As shown, the dispersible surface layer 6, the dispersible absorption layer 5, and the dispersible breathable and leakproof layer are sequentially overlapped and connected from top to bottom; each layer is bonded and connected by a water-soluble adhesive. The width of the dispersible surface layer 6 and the dispersible breathable and leakproof layer is greater than that of the dispersible absorption layer 5; the dispersible surface layer 6 is connected to the periphery of the dispersible breathable and leakproof layer to cover and fix the dispersible absorption layer 5. The upper surface of the surface layer 1 in the dispersible breathable and leakproof layer is connected to the lower surface of the dispersible absorption layer 5.

[0113] The flushable surface layer 6 is a flushable nonwoven fabric; the flushable absorption layer 5 is composed of 90% by mass of fluff pulp and 10% by mass of a high molecular water-absorbent resin (SAP).

[0114] Example 3

[0115] The difference between this embodiment and embodiment 2 is that: the water-swelling polymer powder layer 4 is not provided in the dispersible breathable leakproof layer; and step (3) is not performed in the preparation process of the dispersible breathable leakproof layer. The rest of the structure and preparation process are the same as those of embodiment 2.

[0116] Example 4

[0117] The difference between this embodiment and embodiment 2 is that: in the flushable breathable leakproof layer, the surface layer 1 is made of 30wt% hydrophilic short-cut viscose fibers (fiber specification is 1.67dtex*5mm, and the cross section is circular) and 70wt% ultra-short hydrophobic wood pulp fibers through wet papermaking and drying (the same as the bottom layer 3); in the preparation process of the flushable breathable leakproof layer, step (4) is replaced by the same method as step (1). The rest of the structure and preparation process are the same as those of embodiment 2.

[0118] Example 5

[0119] The difference between this embodiment and embodiment 2 is that: in the flushable breathable leakproof layer, the surface layer 1 is made of 30wt% hydrophilic short-cut viscose fibers (fiber specification is 1.67dtex*5mm, and the cross section is triangular) and 70wt% ultra-short wood pulp fibers through wet spunlace processing; in the preparation process of the flushable breathable leakproof layer, the hydrophilic short-cut viscose fibers with a circular cross section in step (4) are replaced with hydrophilic short-cut viscose fibers with a triangular cross section. The rest of the structure and preparation process are the same as those of embodiment 2.

[0120] Example 6

[0121] The difference between this embodiment and embodiment 2 is that: in the flushable breathable leakproof layer, the bottom layer 3 is made of 10wt% hydrophilic short-cut viscose fibers (fiber specification is 1.67dtex*5mm) and 90wt% ultra-short hydrophobic wood pulp fibers through wet papermaking and drying, and the droplet contact angle of the bottom layer 3 is 150°; in the preparation process of the flushable breathable leakproof layer, the 30wt% hydrophilic short-cut viscose fibers and 70wt% ultra-short hydrophobic wood pulp fibers in step (4) are replaced with 10wt% hydrophilic short-cut viscose fibers and 90wt% ultra-short hydrophobic wood pulp fibers. The rest of the structure and preparation process are the same as those of embodiment 2.

[0122] Example 7

[0123] The difference between this embodiment and embodiment 2 is that: in the flushable breathable leakproof layer, the water-repellent fiber layer 2 is made of 50wt% hydrophobic wood pulp fiber and 50wt% wood pulp fiber through air-laid processing, and the droplet contact angle of the water-repellent fiber layer 2 is 120°; in the preparation process of the flushable breathable leakproof layer, the hydrophobic wood pulp fiber in step (2) is replaced by 50wt% hydrophobic wood pulp fiber and 50wt% wood pulp fiber. The rest of the structure and preparation process are the same as those of embodiment 2.

[0124] Comparative Example 1

[0125] The difference between this comparative example and Example 2 is that the flushable air-permeable leak-proof layer is replaced with a water-soluble polyvinyl alcohol film. The rest of the structure is the same as that of Example 2.

[0126] Comparative Example 2

[0127] The difference between this comparative example and Example 2 is that the volume density of the water-repellent fiber layer 2 in the dispersible breathable and leak-proof layer is 350 kg / m 3 , the mass per unit area is 100g / m 2 , which is made of 100% hydrophobic wood pulp fibers through air-laying and water-entanglement reinforcement; in the preparation process of the dispersible breathable and leak-proof layer, after air-laying in step (2), water-entanglement reinforcement is performed. The rest of the structure and preparation process are the same as those in Example 2.

[0128] Test Case

[0129] The liquid barrier property, flushability, air permeability and structural strength of the anti-leakage layer in Examples 2 to 7 and Comparative Examples 1 to 2 were tested, and the specific method is as follows:

[0130] (1) Liquid barrier: Place the absorbent pad on a horizontal table; take the leakproof layer test sample and place it on the absorbent pad; apply 3 mL of simulated blood to the middle of its upper surface, and then start timing. When the simulated blood penetrates the leakproof layer or the timing exceeds 30 minutes, stop timing and record the leakage time of the test sample.

[0131] (2) Flushability: The test was conducted in accordance with the shaking box decomposition test in GB / T 40181-2021 Flushability test method and evaluation of disposable sanitary nonwoven materials. The test time was 20 min, and the decomposition percentage of the sample was recorded.

[0132] (3) Air permeability: Tested in accordance with GB / T5453 Determination of air permeability of textile fabrics, with a test area of ​​20 cm and a pressure drop of 100 Pa. The air permeability of the sample was recorded as follows:

[0133] (4) Structural strength: The test was conducted in accordance with GB / T 24218.3-2010 Textiles - Nonwoven Fabrics Test Methods - Part 3: Determination of Breaking Strength and Elongation at Break. The test parameters were: fixture 100 mm, tensile speed 100 mm / min, strip width 50 mm, and the dry longitudinal breaking strength of the test sample was recorded.

[0134] The test results are shown in Table 1.

[0135] Table 1

[0136]

[0137]

[0138] Furthermore, in the liquid barrier test, the timing time was extended from 30 min to 50 min, and in the flushability test, the test time was shortened from 20 min to 10 min. The liquid barrier and flushability of Example 2 and Example 5 were tested again, and the leakage time of Example 2 and Example 5 was measured to be 35 min and 43 min, respectively, and the decomposition percentages were 87% and 94%, respectively.

[0139] By analyzing the data in the above table, we can see that:

[0140] (1) The decomposition percentage and air permeability of the anti-leakage layer of Example 2 are significantly higher than those of Comparative Example 1, indicating that the anti-leakage layer of the present invention can be quickly dispersed in water and has an air permeability significantly higher than that of the water-soluble polyvinyl alcohol film.

[0141] (2) The structural strength of the leakproof layer of Example 2 is close to that of Comparative Example 2, while the decomposition percentage is significantly higher than that of Comparative Example 2, indicating that in the leakproof layer of the present invention, compared with the water-repellent fiber layer composed of fibers entangled with each other, the loose distribution of fibers therein is conducive to improving the flushability of the leakproof layer and will not cause excessive impact on the structural strength of the leakproof layer. This is because: in the leakproof layer of the present invention, the surface layer and the bottom layer are composed of fibers entangled with each other, and by wrapping the loose and fluffy water-repellent fiber layer between the surface layer and the bottom layer, the water-repellent fiber layer can be fixed and the structural strength of the leakproof layer can be improved; and in the water-repellent fiber layer, higher water repellency will affect its flushability, and designing it into a fluffy state with loosely distributed fibers can solve the problem of decreased water dispersibility caused by improved water repellency.

[0142] (3) Compared with Example 2, the leakage time of Example 3 is shorter, indicating that the liquid barrier property of the leak-proof layer can be improved by providing a water-absorbing and swelling polymer powder layer between the surface layer and the water-repellent fiber layer. This is because: when the liquid contacts the water-absorbing and swelling polymer powder layer, the water-absorbing and swelling polymer powder therein can absorb the liquid and combine with each other to form a strong lubricating film around it, thereby slowing down the infiltration of the liquid.

[0143] (4) Compared with Example 2, Example 4 has a shorter leakage time and local leakage occurs during the test, indicating that in the leak-proof layer, compared with designing the entire leak-proof layer to be hydrophobic, the use of a hydrophilic surface layer can improve the liquid barrier property of the leak-proof layer. This is because: during the use of disposable absorbent sanitary products, when the liquid in the absorbent layer infiltrates into the leak-proof layer, the hydrophilic surface layer can disperse the liquid (the liquid diffuses along the surface layer to the surroundings while infiltrating), avoiding the concentration of the infiltrating liquid and causing local penetration.

[0144] (5) Compared with Example 2, Example 5 has a longer leakage time and a larger decomposition percentage, indicating that by using special-shaped cross-section fibers in the surface layer of the leak-proof layer, the liquid isolation and flushability of the leak-proof layer can be improved. This is because: for the hydrophilic surface layer, the special-shaped cross-section fibers have a larger specific surface area, which can accelerate the diffusion of liquid along the surface layer to the surroundings, thereby better avoiding the concentration of infiltrating liquid and causing local penetration; and after the special-shaped cross-section fibers are entangled, the pores between the fibers are larger, which are very easy to disperse under the impact of high-pressure water flow, thereby improving the flushability of the leak-proof layer.

[0145] (6) Compared with Example 2, the decomposition percentage of Example 6 is significantly smaller, while the liquid barrier property is not significantly increased. The leakage time of Example 7 is significantly shorter, while the decomposition percentage is not significantly reduced. This indicates that by designing the water repellency of the bottom layer to be smaller than that of the water-repellent fiber layer, the leak-proof layer can have both good flushability and liquid barrier properties. This is because: the fibers in the bottom layer are entangled with each other. Therefore, in order to ensure that the water flow can penetrate into the leak-proof layer through the bottom layer to disperse and disintegrate it after use, the water repellency of the bottom layer should not be too large; the fibers in the water-repellent fiber layer are loosely distributed and easy to disperse and disintegrate. Therefore, on the premise of ensuring good flushability, the water-repellent fiber layer can be set to have a relatively high water repellency.

[0146] The raw materials and equipment used in the present invention, unless otherwise specified, are all commonly used raw materials and equipment in the art; the methods used in the present invention, unless otherwise specified, are all conventional methods in the art.

[0147] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a highly air-permeable, dispersible, leak-proof layer, characterized in that: The following steps are involved: (1) forming a web of ultra-short fibers, and then entangle the ultra-short fibers with each other to form reinforced surface sheets and bottom sheets respectively; The surface sheet is a hydrophilic material, and the bottom sheet is a hydrophobic material; (2) Placing the water-repellent fiber between the surface sheet and the bottom sheet to form a loose water-repellent fiber layer; The water repellency of the water repellent fiber layer is greater than that of the bottom sheet; (3) The periphery of the bottom sheet is connected to the periphery of the surface sheet at the top and bottom, so that the water-repellent fiber layer is covered and fixed to form a highly breathable and dispersible leak-proof layer.

2. The preparation method according to claim 1, characterized in that Specific process of step (2) The method comprises the following steps: placing water-repellent fibers on a bottom sheet to form a loose water-repellent fiber layer, applying water-absorbing and swelling polymer powder to the upper surface of the water-repellent fiber layer to form a water-absorbing and swelling polymer powder layer, and then laminating the surface sheet onto the water-absorbing and swelling polymer powder layer.

3. The preparation method according to claim 2, characterized in that: The water-absorbing and swelling polymer powder is applied to the upper surface of the water-repellent fiber layer by means of powdering or electrostatic spraying.

4. The preparation method according to claim 2, characterized in that: The water-absorbing and swelling polymer powder comprises water-absorbing biomass material powder.

5. The preparation method according to claim 1, characterized in that: In step (1), part or all of the ultra-short fibers used to prepare the surface sheet are fibers with special-shaped cross-sections.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The specific process of step (1) includes the following steps: (1.1) The hydrophilic ultrashort fibers are formed into a web, and then the fibers are entangled and reinforced to form a surface sheet; (1.2) Ultra-short hydrophobic fibers, or a mixture of ultra-short hydrophobic fibers and ultra-short hydrophilic fibers, are formed into a web, and the fibers are entangled and reinforced to form a bottom sheet.

7. A highly air-permeable, dispersible, leak-proof layer prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the highly breathable dispersible leak-proof layer as claimed in claim 7 in absorbent sanitary products.

9. The use according to claim 8, characterized in that The absorbent sanitary product comprises, from top to bottom, a flushable surface layer, a flushable absorbent layer and the highly breathable flushable leak-proof layer; the upper surface of the surface layer is in contact with the lower surface of the flushable absorbent layer; the periphery of the flushable surface layer is connected to the periphery of the leak-proof layer; and the four sides of the flushable absorbent layer are covered and fixed by the flushable surface layer and the leak-proof layer.

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