Nursing pad with gradient absorption structure and composite process thereof

Abstract

The present invention discloses a nursing pad with a gradient absorption structure and a composite process thereof, relating to the field of nursing pads. The nursing pad comprises: a flow-guiding surface layer, an absorption layer, a water-locking support layer, a microchannel layer, and a PE film bottom layer, which are composited in sequence from top to bottom; the absorption layer comprises low-crosslinked SAP and fluff pulp, and has a thickness of 3-4 mm; the water-locking support layer comprises high-crosslinked SAP, PVA fiber, and hot-melt adhesive powder, and has a thickness of 2-3 mm; the density of the absorption layer is 0.1-0.15 g / cm 3 The density of the water-locking support layer is 0.3-0.4 g / cm 3 , used to form a density gradient structure from the absorbent layer to the water-locking support layer. By building on the rapid water absorption properties of the low-crosslinked SAP in the absorbent layer, combined with the highly crosslinked SAP and the rigid network of PVA fibers in the water-locking support layer, a gradient density structure of soft core and hard shell is formed. This avoids the uneven thickness problem caused by the disordered accumulation of SAP in traditional homogeneous structures, thereby further improving the fit of the nursing pad to the skin and reducing the risk of pressure sores caused by localized pressure concentration.

Description

Technical Field

[0001] The present invention relates to the technical field of nursing pads, in particular to a nursing pad characterized by an absorption medium, specifically a nursing pad with a gradient absorption structure and a composite process thereof. Background Art

[0002] As a disposable sanitary product, nursing pads are widely used in long-term bedridden patients, postoperative rehabilitation people, incontinent people and infant care scenarios. Their core function is to quickly absorb liquid, keep the surface dry and prevent leakage, thereby reducing the risk of complications related to moist skin (such as pressure sores and eczema).

[0003] Traditional nursing pads often feature a homogenized absorbent structure, typically consisting of a non-woven surface layer, an absorbent core, and a bottom layer of leak-proof membrane. The absorbent core primarily absorbs and locks in liquid through a simple mixture of super absorbent polymer (SAP) and fluff pulp. To improve absorbency, some solutions have increased the SAP content or thickened the core, but these designs have inherent drawbacks:

[0004] On the one hand, after the internal SAP absorbs liquid repeatedly, the sodium carboxylate groups (-COO⁻Na + ) forms a hydration layer with water molecules, resulting in enhanced chain segment mobility and swelling, resulting in significant volume expansion. The homogeneous structure lacks gradient constraints, which makes the core prone to local accumulation and fracture. The maximum deformation often exceeds 5 mm, which reduces the fit between the nursing pad and the skin, not only affecting the patient's activity comfort, but also increasing the risk of pressure sores due to local pressure concentration. On the other hand, when the core after absorption is under pressure (such as when the patient turns over or changes position), the free water squeezed out of the SAP hydrogel network under pressure can easily penetrate back to the surface through the fiber gaps, and the back-seepage amount generally exceeds 8 g, causing the skin to be in a humid environment for a long time. Long-term humid environment can easily cause complications such as eczema and infection.

[0005] Therefore, it is necessary to improve the deficiencies in the prior art to solve the above problems. Summary of the Invention

[0006] The present invention overcomes the shortcomings of the existing technology and provides a nursing pad with a gradient absorption structure and its composite process. By designing a collaborative structure of a multi-layer gradient absorption structure and a bionic microchannel layer for drainage, precise control of the swelling deformation and the pressure backflow amount is achieved, thereby significantly improving the fit, dryness and safety of the nursing pad.

[0007] To achieve the above object, the technical solution adopted by the present invention is: a nursing pad with a gradient absorption structure and a composite process thereof, comprising: a guide surface layer, an absorption layer, a water-locking support layer, a microchannel layer and a PE film bottom layer composited in sequence from top to bottom;

[0008] The absorption layer comprises low-crosslinked SAP and 55-65 wt% fluff pulp, with a thickness of 3-4 mm; the water-locking support layer comprises high-crosslinked SAP, 20-30 wt% PVA fiber and 4-6 wt% hot melt adhesive powder, with a thickness of 2-3 mm;

[0009] The density of the absorption layer is 0.1-0.15 g / cm 3 The density of the water-locking support layer is 0.3-0.4 g / cm 3 , used to form a density gradient structure from the absorption layer to the water-locking support layer;

[0010] The microchannel layer is made of PET / PE bicomponent fiber through gradient needle punching, with a gradient pore size of 60-90 μm in the upper layer and 15-25 μm in the lower layer, and a thickness of 0.5-1 mm.

[0011] In a preferred embodiment of the present invention, the crosslinking agent of the low-crosslinked SAP is N,N'-methylenebisacrylamide, and the addition amount is 0.1-0.3 wt%; the length of the fluff pulp is 4-9 mm.

[0012] In a preferred embodiment of the present invention, the crosslinking agent of the highly crosslinked SAP is N,N'-methylenebisacrylamide, and the addition amount is 1-1.5 wt%; the diameter of the PVA fiber is 10-20 μm, and the molecular weight is 70,000-90,000.

[0013] In a preferred embodiment of the present invention, the diameter of the PET / PE bicomponent fiber is 15-20 μm, and the upper layer needle punching density is 20-30 needles / cm 2 The lower layer has a needle density of 40-50 needles / cm 2 .

[0014] In a preferred embodiment of the present invention, the diversion surface layer is a spunlace nonwoven fabric composed of 25-35 wt% polyester staple fiber and 65-75 wt% viscose fiber, with a gram weight of 40-50 g / m 2 The specifications of the polyester staple fiber are 1.2-1.8 dtex×45-55 mm, and the specifications of the viscose fiber are 1.0-1.5 dtex×35-40 mm.

[0015] In a preferred embodiment of the present invention, the thickness of the PE film bottom layer is 0.02-0.03 mm.

[0016] The present invention provides a composite process for a nursing pad having a gradient absorption structure, comprising the following steps:

[0017] S1. The guide surface layer, the absorption layer, the water-locking support layer, the microchannel layer, and the PE film bottom layer are laminated sequentially by hot melt adhesive spiral coating, ultrasonic spot welding, hot melt mesh bonding, and local gluing processes;

[0018] S2. The product of S1 is heat-pressed and laminated, and cut to obtain a nursing pad with a gradient absorption structure.

[0019] In a preferred embodiment of the present invention, in step S1, the hot melt adhesive spirally coated is polyamide hot melt adhesive, and the coating amount is 5-7 g / m 2 , spiral diameter 2-4 mm, spacing 4-6 mm; the frequency of ultrasonic spot welding is 18-22 kHz, the welding spot diameter is 0.6-1.0 mm, the row spacing is 3-5 mm, and the column spacing is 5-7 mm.

[0020] In a preferred embodiment of the present invention, in step S1, the hot melt web bonding is performed using an EVA web with a gram weight of 10-15 g / m 2 , hot pressing temperature 110-130 ℃, pressure 0.1-0.3 MPa, time 3-7 s; the local bonding is only applied to the 1-3 cm area of ​​the longitudinal center axis with a coating amount of 3-5 g / m 2 .

[0021] In a preferred embodiment of the present invention, in step S2, the pressure of the hot pressing composite is 0.1-0.3 MPa, the temperature is 90-110° C., and the time is 1-4 s.

[0022] The present invention solves the defects existing in the background technology and has the following beneficial effects:

[0023] (1) The present invention provides a nursing pad with a gradient absorption structure and its composite process. By constructing the rapid water absorption characteristics of the low-crosslinked SAP in the absorption layer and combining the rigid network of the high-crosslinked SAP and PVA fibers in the water-locking support layer, a gradient density structure of a soft core and a hard shell is formed. The low-crosslinked SAP network has a low density, and when absorbing water, the chain segments can fully stretch to form a water bridge structure, quickly capturing liquid; while the high-crosslinked SAP network is dense and the chain segments are rigid. The hydroxyl groups of the PVA fibers form ionic bonds with the SAP carboxyl groups to construct a rigid support skeleton, which limits the lateral extension of the low-crosslinked SAP and thereby inhibits its swelling and deformation, avoiding the uneven thickness problem caused by the disordered stacking of SAP in the traditional homogeneous structure, thereby further improving the fit of the nursing pad to the skin and reducing the risk of pressure sores caused by local pressure concentration.

[0024] (2) The bionic microchannel layer in the present invention has a larger pore size in the upper layer in contact with the water-locking support layer, and a smaller pore size in the lower layer in contact with the PE membrane, forming a pore size gradient from large to small. The surface of the upper PET / PE fiber forms a low surface energy area due to the melting of the PE cortex, and the contact angle with water is large, which is conducive to liquid infiltration. The dense arrangement of the lower fiber increases the surface energy and reduces the contact angle. The capillary pressure difference from large pores to small pores drives the liquid to flow in a directional manner, changing the phenomenon of random liquid penetration under pressure in traditional nursing pads, actively guiding the exudate to the bottom layer, avoiding back seepage to the surface layer and causing skin moisture, thereby significantly reducing the probability of eczema or infection and improving the safety of long-term use.

[0025] (3) The rigid skeleton of the water-locking support layer and the active drainage of the microchannel layer in the present invention form a dual mechanism of inhibition and drainage. Its highly cross-linked SAP network limits the swelling space through covalent bonds, reducing the free water extrusion pressure. The microchannel transfers the exudate in time through the surface energy gradient, reducing the internal hydraulic pressure of the water-locking support layer, and thus can synergistically break through the performance contradiction of traditional nursing pads in absorbing liquid, locking liquid and preventing leakage. It can still maintain ultra-low deformation and back-seepage under multiple liquid impacts and continuous pressure, thereby achieving a simultaneous improvement in absorption efficiency and wearing comfort, providing reliable nursing protection for long-term bedridden patients. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments described in the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive efforts.

[0027] Figure 1 is a cross-sectional structural diagram of a nursing pad according to a preferred embodiment of the present invention;

[0028] In the figure: 1. Diversion surface layer; 2. Absorption layer; 3. Water-locking support layer; 4. Microchannel layer; 5. PE film bottom layer. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0030] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0031] It should be noted that the raw materials, equipment or reagents used in the present invention can be purchased from the market or obtained through existing preparation methods.

[0032] like Figure 1 As shown, a nursing pad with a gradient absorption structure and its composite process include: a flow-guiding surface layer 1, an absorption layer 2, a water-locking support layer 3, a microchannel layer 4, and a PE film bottom layer 5, which are composited in sequence from top to bottom; the absorption layer 2 contains low-crosslinked SAP and 55-65 wt% fluff pulp, with a thickness of 3-4 mm; the water-locking support layer 3 contains high-crosslinked SAP, 20-30 wt% PVA fiber and 4-6 wt% hot-melt adhesive powder, with a thickness of 2-3 mm; the density of the absorption layer 2 is 0.1-0.15 g / cm 3 The density of the water-locking support layer 3 is 0.3-0.4 g / cm 3 , used to form a density gradient structure from the absorption layer 2 to the water-locking support layer 3; the microchannel layer 4 is made of PET / PE two-component fiber by gradient needle punching, and the gradient pore size is formed into 60-90 μm for the upper layer and 15-25 μm for the lower layer, with a thickness of 0.5-1 mm.

[0033] In some specific embodiments, the crosslinking agent of the low-crosslinked SAP is N,N'-methylenebisacrylamide, and the addition amount is 0.1-0.3 wt%; the length of the fluff pulp is 4-9 mm.

[0034] It should be noted that the preparation of the absorption layer 2 includes the following steps: low-crosslinked SAP and 0.3-0.7 wt% silane coupling agent are mixed at a rotation speed of 2500-3200 rpm for 3-7 min, and then air-laid with fluff pulp at a wind speed of 10-15 m / s to form a fluffy layer to obtain the absorption layer 2.

[0035] In some specific embodiments, the crosslinking agent of the highly crosslinked SAP is N,N'-methylenebisacrylamide, and the addition amount is 1-1.5 wt%; the diameter of the PVA fiber is 10-20 μm, and the molecular weight is 70,000-90,000.

[0036] It should be noted that the preparation of the water-locking support layer 3 includes the following steps: high-cross-linked SAP, PVA fiber and hot melt adhesive powder are dry-mixed and granulated through a twin-screw extruder at a temperature of 120-140 ° C and a speed of 150-250 rpm. After crushing, the mixture is passed through a flat die hot press at a temperature of 120-140 ° C and a pressure of 0.2-0.4 MPa for 10-20 s to obtain the water-locking support layer 3.

[0037] In some specific embodiments, the diameter of the PET / PE bicomponent fiber is 15-20 μm, and the upper layer needle punching density is 20-30 needles / cm 2 The lower layer has a needle density of 40-50 needles / cm 2 .

[0038] It should be noted that the preparation of the microchannel layer 4 includes the following steps: PET / PE bicomponent fibers are passed through a double-zone needle punching machine, with the upper layer being punched at 20-30 needles / cm 2 The density of needle punching is 40-50 needles / cm 2 The microchannel layer 4 is obtained by needle punching at a density of 110-130°C and hot air treatment for 1-3 minutes.

[0039] In some specific embodiments, the flow-guiding surface layer 1 is a spunlace nonwoven fabric composed of 25-35 wt% polyester staple fiber and 65-75 wt% viscose fiber, with a gram weight of 40-50 g / m 2 ; The specifications of polyester staple fiber are 1.2-1.8 dtex×45-55 mm, and the specifications of viscose fiber are 1.0-1.5 dtex×35-40 mm.

[0040] It should be noted that the preparation of the diversion surface layer 1 includes the following steps: passing the polyester staple fiber and the viscose fiber through a carding machine, opening and mixing them at a carding speed of 1.0-1.5 m / min to form a preliminary web, vertically spraying the fiber web with a high-pressure water flow of 70-90 bar pressure and 0.08-0.12 mm pore size, and after hydroentanglement reinforcement, forming a 40-50 g / m 2 The non-woven fabric is sprayed with 0.5-1 wt% alkyl glycoside solution and dried to obtain a diversion surface layer 1.

[0041] In some specific embodiments, the thickness of the PE film bottom layer 5 is 0.02-0.03 mm.

[0042] The present invention provides a composite process for a nursing pad having a gradient absorption structure, comprising the following steps:

[0043] S1. The guide surface layer 1, the absorption layer 2, the water-locking support layer 3, the microchannel layer 4 and the PE film bottom layer 5 are laminated by spiral coating of hot melt adhesive, ultrasonic spot welding, hot melt mesh bonding and local gluing processes in sequence;

[0044] S2. The product of S1 is heat-pressed and laminated, and cut to obtain a nursing pad with a gradient absorption structure.

[0045] In some specific embodiments, in step S1, the hot melt adhesive spiral coating is a polyamide hot melt adhesive with a coating amount of 5-7 g / m 2 , spiral diameter 2-4 mm, spacing 4-6 mm; the frequency of ultrasonic spot welding is 18-22 kHz, the weld spot diameter is 0.6-1.0 mm, the row spacing is 3-5 mm, and the column spacing is 5-7 mm.

[0046] In some specific embodiments, in step S1, the hot melt web bonding uses EVA web with a gram weight of 10-15 g / m 2 , hot pressing temperature 110-130 ℃, pressure 0.1-0.3 MPa, time 3-7 s; local bonding is only applied to the 1-3 cm area of ​​the longitudinal center axis with water-based polyurethane glue, and the glue coating amount is 3-5 g / m 2 .

[0047] In some specific embodiments, in step S2, the pressure of the hot pressing composite is 0.1-0.3 MPa, the temperature is 90-110° C., and the time is 1-4 s.

[0048] In order to further make the purpose and effect of the present invention simple and easy to understand, the present invention is further described in conjunction with the following specific examples and comparative examples, but the present invention is not limited to the scope of the embodiments.

[0049] It should be noted that in the examples and comparative examples, the preparation of raw materials is described as follows: SAP: purity ≥99%, purchased from Zhengzhou Chengjin Chemical; N,N'-methylenebisacrylamide: purity ≥99%, CAS No. 110-26-9, purchased from Jinan Qingtian Chemical; hot melt adhesive powder: particle size 200 mesh, brand 1800D, purchased from Dongguan Hongkuo Plastic; silane coupling agent KH550: purity ≥99%, purchased from Shandong Jinli Chemical; alkyl glycoside: purity ≥99%, purchased from Hubei Maidehao Biological; polyamide hot melt adhesive: purity ≥99%, purchased from Shenzhen Dezhibang; water-based polyurethane adhesive: purity ≥99%, purchased from Shanghai Hecheng Polymer; the diameter of the PVA fiber is 15 μm and the molecular weight is 80,000; the diameter of the PET / PE bicomponent fiber is 18 μm; the specification of the polyester staple fiber is 1.5 dtex×50mm; the specification of the viscose fiber is 1.3 dtex×40 mm; the length of the fluff pulp is 6 mm. Example 1

[0050] A preparation process of a nursing pad with a gradient absorption structure comprises the following steps:

[0051] S1, 30 wt% polyester staple fiber and 70 wt% viscose fiber were passed through a carding machine, opened and mixed at a carding speed of 1.2 m / min to form a preliminary web, and the fiber web was vertically sprayed with a high-pressure water flow of 80 bar pressure and 0.1 mm pore size to entangle the fibers with each other, forming a 45 g / m 2 The non-woven fabric was sprayed with 0.8 wt% alkyl glycoside solution, dried with hot air at 100 °C for 30 s, and cut into a 100 cm*100 cm diversion surface layer 1;

[0052] S2. 0.2 wt% N,N'-methylenebisacrylamide was mixed with SAP with a particle size of 400 μm to form low cross-linked SAP. The low cross-linked SAP was mixed with 0.3-0.7 wt% KH550 in a high-speed mixer at a speed of 3000 rpm for 5 min. Then, fluff pulp with a total weight of 20% of the low cross-linked SAP was added. The two were evenly dispersed at a wind speed of 12 m / s to form a density of 0.12 g / cm on the forming mesh curtain. 3 , a fluffy layer with a thickness of 3.5 mm, cut to obtain an absorbent layer 2 with a size of 95 cm*95 cm;

[0053] S3. 1.2 wt% N,N'-methylenebisacrylamide was mixed with SAP with a particle size of 400 μm to form highly cross-linked SAP. 70 wt% highly cross-linked SAP, 25 wt% PVA fiber and 5 wt% hot melt adhesive powder were dry-mixed through a twin-screw extruder at a temperature of 130 °C and a speed of 200 rpm to extrude columnar particles with a diameter of 2 mm. After cooling, the particles were crushed to a particle size of 650 μm. The particles were then pressed through a flat die hot press at a temperature of 130 °C and a pressure of 0.3 MPa for 15 s to obtain a density of 0.35 g / cm 3 , a rigid sheet with a thickness of 2.5 mm is cut to obtain a water-locking support layer 3 of 95 cm*95 cm;

[0054] S4, the PET / PE bicomponent fiber is passed through a double-zone needle punching machine, with the upper layer at 25 needles / cm 2 The density of needle punching was 75 μm, and the lower layer was punched at 45 needles / cm 2 The density of the fibers was needle-punched to form a pore size of 20 μm, and then the fibers were subjected to a hot air treatment at 120°C for 2 min to partially melt the PE cortex and bond the fiber nodes. The microchannel layer 4 was cut to obtain a size of 95 cm*95 cm and a thickness of 0.8 mm.

[0055] S5, cutting a PE film with a thickness of 0.03 mm to obtain a PE film bottom layer 5 of 100 cm*100 cm;

[0056] S6, use polyamide hot melt adhesive with a density of 6 g / m2 between the diversion surface layer 1 and the absorption layer 2. 2 The amount of glue applied was 3 mm spiral diameter, 5 mm spacing, and spiral coating was performed. The absorption layer 2 and the water-locking support layer 3 were ultrasonically spot welded at a frequency of 20 kHz, a welding spot diameter of 0.8 mm, a row spacing of 4 mm, and a column spacing of 6 mm. The water-locking support layer 3 and the microchannel layer 4 were welded with a 12 g / m 2 The EVA mesh of 100 grams was hot-melt bonded at a temperature of 120 ° C, a pressure of 0.2 MPa, and a heat press of 5 seconds. The microchannel layer 4 and the PE film bottom layer 5 were bonded at a pressure of 4 g / m 2 Glue application amount, apply water-based polyurethane glue, and perform local adhesive bonding;

[0057] S7. The product of S6 was hot-pressed and laminated at a pressure of 0.2 MPa and a temperature of 100°C for 3 s to obtain a nursing pad with a gradient absorption structure. Example 2

[0058] This embodiment is basically the same as embodiment 1, except that the density of the absorption layer 2 is 0.1 g / cm 3 . Example 3

[0059] This embodiment is basically the same as embodiment 1, except that the density of the absorption layer 2 is 0.15 g / cm 3 . Example 4

[0060] This embodiment is basically the same as embodiment 1, except that the density of the water-locking support layer 3 is 0.3 g / cm 3 . Example 5

[0061] This embodiment is basically the same as embodiment 1, except that the density of the water-locking support layer 3 is 0.4 g / cm 3 . Example 6

[0062] This embodiment is basically the same as the embodiment 1, with the difference being that the pore size of the upper layer of the microchannel layer 4 is 60 μm. Example 7

[0063] This embodiment is basically the same as the embodiment 1, with the difference being that the pore size of the upper layer of the microchannel layer 4 is 90 μm. Example 8

[0064] This embodiment is basically the same as the embodiment 1, except that the pore size of the lower layer of the microchannel layer 4 is 15 μm. Example 9

[0065] This embodiment is basically the same as embodiment 1, with the difference being that the pore size of the upper layer of the microchannel layer 4 is 25 μm.

[0066] Comparative Example 1

[0067] Commercially available nursing pads: The structure includes a surface non-woven fabric, a bottom PE film, and an absorbent core composed of SAP and fluff pulp located between the surface and bottom layers. The size is 80cm*60cm and was purchased from Henan Chongde Medical Equipment.

[0068] Comparative Example 2

[0069] This comparative example is basically the same as Example 1, except that the density of the absorption layer 2 and the density of the water-locking support layer 3 are both 0.35 g / cm 3 .

[0070] Comparative Example 3

[0071] This comparative example is basically the same as Example 1, except that the density of the absorption layer 2 and the density of the water-locking support layer 3 are both 0.12 g / cm 3 .

[0072] Comparative Example 4

[0073] This comparative example is basically the same as Example 1, except that the density of the absorbent layer 2 is 0.35 g / cm 3 The density of the water-locking support layer 3 is 0.12 g / cm 3 .

[0074] Comparative Example 5

[0075] This comparative example is basically the same as Example 1, except that no crosslinking agent is added to the SAP of the absorption layer 2 and the water-locking support layer 3 .

[0076] Comparative Example 6

[0077] This comparative example is basically the same as Example 1, except that: no microchannel layer 4 is added to the nursing pad, that is, there is no step S4, and in step S6, the water-locking support layer 3 and the PE film bottom layer 5 are hot-melt-bonded.

[0078] Comparative Example 7

[0079] This comparative example is basically the same as Example 1, except that: in the microchannel layer 4, the pore diameters of the upper layer and the lower layer are both 75 μm.

[0080] Comparative Example 8

[0081] This comparative example is basically the same as Example 1, except that in the microchannel layer 4, the pore diameters of the upper layer and the lower layer are both 20 μm.

[0082] Performance testing: The nursing pads obtained in Examples 1-9, Comparative Examples 2-8, and the commercially available nursing pad of Comparative Example 1 were subjected to performance tests of swelling deformation and pressure rewetting, respectively. The results are shown in Table 1.

[0083] Swelling deformation: Use 50 ml of normal saline and drip it evenly onto the center area of ​​the nursing pad through a separatory funnel at a rate of 5 ml / s. Perform 5 consecutive liquid shocks with an interval of 10 minutes between each shock. Let it stand for 5 minutes after each shock. Use a thickness sensor to evenly select 5 test points on the sample surface (1 point in the center and 4 points around it), record the thickness value, and calculate the maximum deformation: maximum deformation = (average thickness after shock - initial thickness). Take the average value of 3 parallel experiments.

[0084] Pressure backseepage: add 50 ml of normal saline to the center area of ​​the nursing pad, let it stand for 30 minutes until it is completely absorbed, fix the nursing pad on the pressure testing device, apply 4 kPa pressure (simulating the pressure of a lying human body), and press 50 times at a frequency of 60 times / min. After the pressing is completed, immediately take 3 layers of quantitative filter paper (pre-weighed, recorded as W0) to cover the surface of the nursing pad, apply 2 kPa pressure on the top and maintain it for 1 minute to allow the backseepage liquid to be completely absorbed by the filter paper, take out the filter paper and weigh it (recorded as W1), and calculate the backseepage amount: Backseepage amount = W1-W0.

[0085] Table 1: Performance test results of nursing pads of Examples 1-9 and Comparative Examples 1-8

[0086]

[0087] As shown in Table 1:

[0088] A comparison of Examples 1-9 shows that the embodiments of the present invention all achieve low swelling deformation of 1.4-2.1 mm and low rewet amount of 1.8-2.6 g. The core lies in the synergy of the gradient absorption structure and the microchannel layer 4. The low-density and low-crosslinked SAP of the absorption layer 2 enables the molecular chain segments to quickly stretch to form a water bridge structure to capture liquid; the high-density and high-crosslinked SAP of the water-locking support layer 3 restricts the movement of the chain segments through covalent bonds, and the hydroxyl groups of the PVA fibers form ionic bonds with the SAP carboxyl groups to construct a rigid network and inhibit swelling; further, the gradient pore size of the microchannel layer 4 generates a capillary pressure difference, driving the liquid to flow in a directional manner to the bottom layer. The triple mechanism of soft core, hard shell and drainage optimizes the diffusion path of water molecules, reduces free water extrusion and reverse osmosis, and thus maintains ultra-low deformation and rewet under multiple liquid impacts.

[0089] By comparing Example 1 with Comparative Example 1, it can be seen that the traditional sandwich nursing pad is a mixed structure of homogeneous SAP and fluff pulp. SAP and fluff pulp are simply mixed and lack gradient constraints. The sodium carboxylate groups in the SAP molecular chain absorb water to form a hydration layer, which increases the mobility of the chain segments, resulting in uncontrolled swelling. The disordered accumulation of molecular chains causes the local deformation of the core to exceed 5 mm; at the same time, when under pressure, the hydrogel network squeezes out free water, which randomly penetrates through the fiber gaps, and the backflow amount is significantly increased.

[0090] By comparing Example 1 with Comparative Examples 2-3, it can be seen that: the non-gradient density structure causes the maximum deformation of Comparative Example 2 to reach 3.8 mm, and the backseepage amount increases to 6.2 g; the maximum deformation of Comparative Example 3 reaches 4.1 mm, and the backseepage amount increases to 6.5 g; in Comparative Example 2, the high density of the absorption layer 2 and the water-locking support layer 3 runs through the entire structure, the extension of the SAP chain segment of the absorption layer 2 is limited, the water absorption rate decreases, and the water-locking layer lacks elastic buffering. When under pressure, the SAP network is easily broken and the backseepage increases; in Comparative Example 3, the low density of the absorption layer 2 and the water-locking support layer 3 lacks rigid support, the water-locking layer cannot form a rigid support, and the lateral deformation after SAP swelling is poorly suppressed, which will lead to a decrease in fit.

[0091] By comparing Example 1 with Comparative Example 4, it can be seen that: the high density of the absorption layer 2 hinders the initial water absorption of the SAP, and the liquid is retained in the surface layer; the low density of the water-locking layer cannot provide rigid support, and the highly cross-linked SAP expands laterally when swelled due to the lack of PVA fiber network constraints, resulting in a maximum deformation of 4.5 mm. At the same time, the density gradient reversal destroys the hard shell and soft core structure. When under pressure, the liquid easily penetrates back from the water-locking layer to the absorption layer 2, and the back-seepage amount is significantly increased.

[0092] By comparing Example 1 with Comparative Example 5, it can be seen that: since the SAP in the absorption layer 2 and the water-locking layer has no cross-linking agent, the SAP molecular chain has a linear structure, there is no three-dimensional network constraint, the chain segment mobility is extremely strong, the swelling rate increases dramatically after absorbing water, the hydration layer is too thick, and the free water extrusion pressure is large; at the same time, there is a lack of ionic bond stability, the molecular network is easily broken when under pressure, and the backseepage increases, ultimately resulting in a maximum deformation of 4.8 mm and a backseepage amount of up to 7.1 g.

[0093] By comparing Example 1 with Comparative Example 6, it can be seen that: when there is no microchannel layer 4, the liquid seeping out of the water-locking layer cannot be attracted to the bottom layer through capillary siphon, and can only diffuse randomly through the fiber gaps. When under pressure, the liquid accumulates between the water-locking layer and the PE film, forming a hydraulic cushion effect, resulting in an increase in the backflow amount to 7.9 g; however, the rigid skeleton of the water-locking layer can still partially suppress deformation, so the deformation amount is better than the traditional nursing pad in Comparative Example 1 but worse than that in Example 1.

[0094] By comparing Example 1 with Comparative Examples 7-8, it can be seen that: with a suitable pore gradient, the large-pore upper layer reduces the flow resistance, and the small-pore lower layer increases the capillary force, forming a unidirectional pressure gradient; while in Comparative Example 7, there is no capillary pressure difference, the liquid only penetrates by gravity, the liquid is randomly retained, and the backflow amount still increases to 4.4 g when under pressure. The pore size of Comparative Example 8 is too small, resulting in obstruction of liquid infiltration and increased liquid pressure in the water-locking layer. Although the deformation is slightly lower, the backflow is significantly increased.

[0095] The above description is based on the ideal embodiment of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be considered as illustrative and non-restrictive in all respects. The scope of the present invention is defined by the appended claims, not the foregoing description, and it is intended that all variations within the meaning and range of equivalents of the claims be encompassed within the present invention. Any reference signs in the claims should not be construed as limiting the claim to which they relate.

[0096] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A nursing pad with a gradient absorption structure, characterized in that: include: The diversion surface layer, absorption layer, water-locking support layer, microchannel layer and PE film bottom layer are compounded in sequence from top to bottom; The absorption layer is made of low-crosslinked SAP and 55-65 wt% fluff pulp, with a thickness of 3-4 mm; the water-locking support layer is made of high-crosslinked SAP, 20-30 wt% PVA fiber and 4-6 wt% hot melt adhesive powder, with a thickness of 2-3 mm; The crosslinking agents of the low-crosslinked SAP and the high-crosslinked SAP are both N,N'-methylenebisacrylamide, the amount of the crosslinking agent added to the low-crosslinked SAP is 0.1-0.3 wt%, and the amount of the crosslinking agent added to the high-crosslinked SAP is 1-1.5 wt%; The density of the absorption layer is 0.1-0.15 g / cm 3 The density of the water-locking support layer is 0.3-0.4 g / cm 3 , used to form a density gradient structure from the absorption layer to the water-locking support layer; The microchannel layer is made of PET / PE bicomponent fiber through gradient needle punching, with a gradient pore size of 60-90 μm in the upper layer and 15-25 μm in the lower layer, and a thickness of 0.5-1 mm.

2. The nursing pad with a gradient absorption structure according to claim 1, characterized in that: The length of the fluff pulp is 4-9 mm.

3. The nursing pad with a gradient absorption structure according to claim 1, characterized in that: The PVA fiber has a diameter of 10-20 μm and a molecular weight of 70,000-90,000.

4. The nursing pad with a gradient absorption structure according to claim 1, characterized in that: The diameter of the PET / PE bicomponent fiber is 15-20 μm, and the upper layer needle punching density is 20-30 needles / cm 2 The lower layer has a needle density of 40-50 needles / cm 2 .

5. The nursing pad with a gradient absorption structure according to claim 1, characterized in that: The diversion surface layer is a spunlace nonwoven fabric composed of 25-35 wt% polyester staple fiber and 65-75 wt% viscose fiber, with a gram weight of 40-50 g / m 2 The specifications of the polyester staple fiber are 1.2-1.8 dtex×45-55 mm, and the specifications of the viscose fiber are 1.0-1.5 dtex×35-40 mm.

6. The nursing pad with a gradient absorption structure according to claim 1, characterized in that: The thickness of the PE film bottom layer is 0.02-0.03 mm.

7. A composite process for a nursing pad with a gradient absorption structure according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. The guide surface layer, the absorption layer, the water-locking support layer, the microchannel layer, and the PE film bottom layer are laminated sequentially by hot melt adhesive spiral coating, ultrasonic spot welding, hot melt mesh bonding, and local gluing processes; S2. The product of S1 is heat-pressed and laminated, and cut to obtain a nursing pad with a gradient absorption structure.

8. The composite process of a nursing pad with a gradient absorption structure according to claim 7, characterized in that: In the step S1, the hot melt adhesive spiral coating is a polyamide hot melt adhesive with a coating amount of 5-7 g / m 2 , spiral diameter 2-4 mm, spacing 4-6 mm; the frequency of ultrasonic spot welding is 18-22 kHz, the welding spot diameter is 0.6-1.0 mm, the row spacing is 3-5 mm, and the column spacing is 5-7 mm.

9. The composite process of a nursing pad with a gradient absorption structure according to claim 7, characterized in that: In the step S1, the hot melt web bonding is performed using EVA web with a gram weight of 10-15 g / m 2 , hot pressing temperature 110-130 ℃, pressure 0.1-0.3 MPa, time 3-7 s; the local bonding is only applied to the 1-3 cm area of ​​the longitudinal center axis with a coating amount of 3-5 g / m 2 .

10. The composite process of a nursing pad with a gradient absorption structure according to claim 7, characterized in that: In the step S2, the pressure of the hot pressing composite is 0.1-0.3 MPa, the temperature is 90-110° C., and the time is 1-4 s.

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