A fully bio-based absorbent core based on the gradient density structure of seaweed fibers and its preparation method

Abstract

This invention discloses a fully bio-based absorbent core based on a gradient density structure of seaweed fibers and its preparation method. The absorbent core comprises, from top to bottom, a first absorbent layer, a second absorbent layer, and a third absorbent layer along its thickness direction. The first, second, and third absorbent layers are all composed of a mixture of seaweed fibers and biodegradable thermoplastic fibers. The biodegradable thermoplastic fibers are selected from one or more of polylactic acid fibers, polybutylene succinate fibers, and polybutylene adipate terephthalate fibers. The mass percentage of seaweed fibers in the first, second, and third absorbent layers increases in a gradient manner. This absorbent core structure combines rapid absorption, efficient water retention, long-lasting antibacterial properties, and structural stability, and the preparation process is compatible with existing equipment.

Description

Technical Field

[0001] This invention belongs to the field of nursing care products technology, specifically relating to a fully bio-based absorbent core based on a gradient density structure of seaweed fibers and its preparation method. Background Technology

[0002] The absorbent core is the core functional layer of trouser-type absorbent products (such as baby diapers, pull-ups, adult incontinence pants, and women's menstrual pants). Its performance directly determines the product's absorption speed, water retention capacity, anti-backflow effect, and wearing comfort. As consumers' requirements for product safety, environmental protection, and health continue to increase, the material and structural design of the absorbent core has become a key area of ​​technological innovation.

[0003] The absorbent core has mainly gone through the following three generations: The first generation is a composite structure of fluff pulp and superabsorbent polymer (SAP), which has fast absorption and strong water retention, but relies on petroleum-based and wood pulp resources, and is not environmentally friendly enough; The second generation is a composite structure of natural fibers (such as cotton and bamboo fiber) and SAP, which improves environmental friendliness, but the core is still uniformly mixed and the function is not optimized; The third generation is a multi-layer composite and structural optimization structure, which improves liquid diffusion through split or irregular design, but the materials are still mainly based on traditional components, and the preparation is highly complex.

[0004] Seaweed fiber has been introduced into absorbent products in recent years due to its biodegradability, natural antibacterial properties, and high hygroscopicity. However, in existing solutions, seaweed fiber exists only as a homogeneous component, and its functional properties are not graded or structured, resulting in insufficient matching between the liquid absorption pathway and material properties.

[0005] Meanwhile, existing absorber cores also have the following systemic technical defects: The structural contradiction between absorption rate and water-locking capacity: The uniformly mixed structure cannot simultaneously meet the dual requirements of fast surface absorption and water-locking in the bottom layer, resulting in either slow absorption and easy side leakage, or poor water-locking and serious back osmosis.

[0006] The lack of uniformity in material composition: the proportion of components such as seaweed fiber is consistent throughout the entire layer, which fails to meet the differentiated material performance requirements at different depths during the top-down transport of liquid.

[0007] Structural defects in the liquid conduction path: liquid diffusion is random and uncontrollable; SAP easily blocks conduction channels after absorbing water and expanding; lack of a mechanism to guide liquid diffusion to the core edge leads to low core utilization.

[0008] Single antibacterial mechanism and insufficient durability: Relying solely on the natural antibacterial properties of seaweed fiber, the components are easily lost after contact with liquid, the antibacterial effect decays quickly, and there is a lack of a continuous antibacterial design that works in synergy with the absorption structure.

[0009] The contradiction between biodegradability and structural stability: All-bio-based materials such as seaweed fibers are prone to swelling and fiber network collapse after absorbing water. After repeated liquid absorption, the structural integrity decreases, affecting subsequent absorption performance.

[0010] Compatibility issues with production processes: The morphology and surface characteristics of seaweed fiber differ greatly from those of traditional fluff pulp, resulting in poor compatibility with existing air-laid and hot-pressed lamination production lines, making it difficult to guarantee the quality of finished products.

[0011] Therefore, there is an urgent need to develop an absorbent core that combines rapid absorption, efficient water retention, long-lasting antibacterial properties, structural stability, and good process compatibility, as well as its preparation method. Summary of the Invention

[0012] To address at least one of the aforementioned problems, this invention provides a fully bio-based absorbent core based on a seaweed fiber gradient density structure and its preparation method.

[0013] To achieve the above objectives, the present invention employs the following technical means: The first aspect of this invention provides a fully bio-based absorbent core based on a gradient density structure of seaweed fibers. The absorbent core comprises, from top to bottom along its thickness direction, a first absorbent layer, a second absorbent layer, and a third absorbent layer. Each of the first, second, and third absorbent layers is composed of a mixture of seaweed fibers and biodegradable thermoplastic fibers. The biodegradable thermoplastic fibers are selected from one or more of polylactic acid fibers, polybutylene succinate fibers, and polybutylene adipate terephthalate fibers. The mass percentage of seaweed fibers in the first, second, and third absorbent layers increases in a gradient. The mass percentage of seaweed fibers in the first absorbent layer is 10-30%, in the second absorbent layer it is 40-70%, and in the third absorbent layer it is 80-95%.

[0014] In some embodiments of the present invention, the mass ratio of seaweed fiber to biodegradable thermoplastic fiber in the first absorbent layer is (1:3)-(3:7), the denier of the seaweed fiber is 1.0-2.0 D, and the denier of the biodegradable thermoplastic fiber is 1.2-1.8 D.

[0015] In some embodiments of the present invention, the surface of the first absorbent layer is provided with a plurality of wavy guiding grooves along its longitudinal direction. The depth of the guiding grooves is 0.3-0.8 mm, the width is 2-5 mm, and the spacing between adjacent guiding grooves is 8-15 mm.

[0016] In some embodiments of the present invention, the first absorbent layer is provided with a first antibacterial factor, which is silver-loaded nanoparticles with a particle size of 10-50 nm, loaded on the surface of seaweed fiber, and the loading amount is 0.1-0.5% of the mass of seaweed fiber.

[0017] In some embodiments of the present invention, the mass ratio of the second absorbent layer of seaweed fiber to biodegradable thermoplastic fiber is (2:1) to (4:1), the denier of the seaweed fiber is 2.5-4.5 D, and the denier of the biodegradable thermoplastic fiber is 2.0-3.0 D.

[0018] In some embodiments of the present invention, the alginate polysaccharide content of the seaweed fiber in the second absorbent layer is maintained at 8-15%.

[0019] In some embodiments of the present invention, three-dimensional reservoirs composed of calcium alginate fibers are uniformly distributed within the second absorbent layer.

[0020] In some embodiments of the present invention, the three-dimensional liquid reservoir is a hollow spherical or ellipsoidal structure with a diameter of 0.5-1.5 mm and a wall thickness of 0.05-0.15 mm.

[0021] In some embodiments of the present invention, the mass ratio of seaweed fiber to biodegradable thermoplastic fiber in the third absorbent layer is (8:1) to (15:1), the denier of the seaweed fiber is 4.0-6.0 D, and the denier of the biodegradable thermoplastic fiber is 3.0-4.5 D.

[0022] In some embodiments of the present invention, polyhexamethylene guanidine salt is grafted onto the surface of the seaweed fibers in the third absorbent layer, and the amount of polyhexamethylene guanidine salt grafted is 0.5-2.0% of the mass of the seaweed fibers.

[0023] In some embodiments of the present invention, a biodegradable microporous film is laminated to the bottom surface of the third absorbent layer. The biodegradable microporous film has a thickness of 0.015-0.030 mm, a pore size of 0.5-2.0 μm, and a porosity of 20-40%.

[0024] A second aspect of the present invention provides a method for preparing the all-bio-based absorbent core described in the first aspect, comprising the following steps: S1. Raw material preparation: Fiber raw material preparation: Opening treatment is carried out on seaweed fiber raw materials and biodegradable thermoplastic fiber raw materials; Three-dimensional liquid storage bladders, silver-loaded seaweed fibers, polyhexamethylene guanidine salt-grafted seaweed fibers, and biodegradable microporous membranes were prepared for use. S2. Preparation of the first absorption layer: The silver-loaded seaweed fiber and the biodegradable thermoplastic fiber raw material are mixed in a certain proportion and formed into a fiber web by an airflow web forming device. The airflow velocity for web forming is 12-18 m / s, and the fiber conveying speed is 8-12 m / s. The fiber web is then fed into a hot air bonding device for bonding. The hot air temperature is 120-135 ℃, the air velocity is 10-15 m / s, and the bonding time is 3-8 s. After bonding, the fiber web is formed into a wavy flow-guiding groove on its surface by a hot pressing molding device. The hot pressing temperature is 100-115 ℃, the hot pressing pressure is 0.2-0.4 MPa, and the molding speed is 5-10 m / min. S3, Prepare the second absorber layer The seaweed fiber raw material and the biodegradable thermoplastic fiber raw material are mixed in a certain proportion, and the three-dimensional liquid storage bladder, accounting for 5-15% of the total fiber mass, is added. The mixture is then formed into a fiber web using an airflow web forming device with an air velocity of 10-15 m / s and a fiber conveying speed of 6-10 m / s. The fiber web is then pre-compressed with a pre-compression pressure of 0.05-0.15 MPa. The pre-compressed fiber web is then fed into a hot air bonding device for bonding, with a hot air temperature of 125-140℃, an air velocity of 12-18 m / s, and a bonding time of 5-10 s. S4. Preparation of the third absorption layer The polyhexamethylene guanidine salt-grafted seaweed fiber is mixed with the biodegradable thermoplastic fiber raw material in a certain proportion, and a fiber web is formed by wet web forming equipment. The fiber slurry concentration is 0.1-0.5%, and the web forming speed is 5-10 m / min. The fiber web formed by wet web forming is dehydrated and dried, and then sent to a hot press for hot pressing and shaping. The hot pressing temperature is 130-150℃, and the hot pressing pressure is 0.5-1.0 MPa. S5, Composite Biodegradable Microporous Film The biodegradable microporous film and the third absorbent layer are bonded together by hot pressing at a temperature of 120-130°C and a pressure of 0.2-0.4 MPa. S6, Multilayer Composite The first absorbent layer, the second absorbent layer, and the third absorbent layer are stacked in order from top to bottom and sent into a hot air bonding equipment for overall composite bonding. The hot air temperature is 125-135℃, the wind speed is 10-15 m / s, and the bonding time is 5-10 s, so that the polylactic acid fibers at the interface between the layers melt and bond together to form an integrated absorbent core. S7, Finished product molding The composite absorbent core is cut to a predetermined size to obtain the finished product.

[0025] The absorbent core prepared according to the above method has a polylactic acid (PLA) fiber content decreasing from 70% to 90% in the first absorbent layer to 5% to 20% in the third absorbent layer. During hot air bonding, partial melting occurs, forming thermal bonding cross-linking points at fiber intersections, which cross-link to form a stable three-dimensional network skeleton. Simultaneously, seaweed fibers and PLA fibers form an intertwined fiber network structure during airflow web formation. By controlling the airflow speed and fiber transport speed, the fibers randomly intertwine during deposition. The thermal bonding cross-linking points and the fiber intertwining structure synergistically constitute an anti-swelling network: when seaweed fibers absorb water and swell, their diameter increases and their length shortens, but due to their intertwining with PLA fibers, the swelling stress is dispersed throughout the fiber network, avoiding fiber network rupture caused by localized stress concentration. At the same time, the cross-linking points limit the macroscopic deformation of the fiber network, maintaining the overall structural integrity of the core.

[0026] In some embodiments of the present invention, the preparation process of the three-dimensional reservoir is as follows: a sodium alginate solution with a mass percentage of 2-5% is dripped into a calcium chloride coagulation bath with a mass percentage of 1-3% using a micro-injection pump at a flow rate of 0.5-2 mL / min to form calcium alginate gel microspheres; the gel microspheres are kept in the coagulation bath for 30-60 min to allow the cross-linking reaction to proceed fully; the gel microspheres are removed and washed with water 3-5 times, and then freeze-dried at a temperature of -20℃ to -40℃ for 24-48 hours to obtain a porous three-dimensional reservoir.

[0027] In some embodiments of the present invention, the preparation process of the silver-loaded seaweed fiber is as follows: the seaweed fiber is immersed in a silver nitrate solution with a concentration of 0.01-0.05 mol / L for 30-60 min, and the immersed seaweed fiber is irradiated under ultraviolet light for 30-90 min with an ultraviolet wavelength of 254 nm and a power of 20-50 W, so that the silver ions are reduced to silver nanoparticles and deposited on the fiber surface; the silver-loaded seaweed fiber is washed with water 3-4 times and dried at a temperature of 50-60℃.

[0028] In some embodiments of the present invention, the preparation process of the polyhexamethylene guanidine salt-grafted seaweed fiber is as follows: the seaweed fiber is immersed in a polyhexamethylene guanidine salt solution with a concentration of 0.5-2.0%, the pH is adjusted to 8.0-9.0, and the reaction is carried out at a temperature of 40-60°C for 2-4 hours; after the reaction is completed, the fiber is taken out, washed with water until neutral, and dried at a temperature of 50-60°C to obtain the polyhexamethylene guanidine salt-grafted seaweed fiber.

[0029] In some embodiments of the present invention, the preparation process of the biodegradable microporous film is as follows: polylactic acid and polybutylene adipate terephthalate are blended and granulated at a mass ratio of (3:7)-(5:5), and extruded into a film at a temperature of 180-200°C using a casting extrusion device. The film is then stretched longitudinally and laterally to form a microporous structure, with a longitudinal stretching ratio of 2.0-3.0 and a lateral stretching ratio of 2.5-3.5.

[0030] Beneficial effects of the present invention Compared with the prior art, the present invention has the following beneficial effects: This invention achieves structural decoupling of absorption rate and water-locking capacity through gradient density structural design; it synergistically enhances absorption capacity and structural stability by introducing a three-dimensional liquid reservoir; it constructs a functional zoned conduction network to actively guide the liquid conduction path; multiple antibacterial strategies work together to achieve long-lasting antibacterial activity throughout the entire pathway and time period; it employs a combination of thermally bonded crosslinking points and fiber winding structures to construct an anti-swelling network, solving the structural instability problem of water absorption and swelling in all-bio-based materials; it achieves a multi-functional modification of seaweed fibers to multiply the performance of a single material; and it achieves good compatibility with existing production lines through optimized design of the manufacturing process. Furthermore, the absorbent core of this invention meets the requirements of national mandatory and recommended standards such as GB 43631-2023, GB 15979-2024, and GB / T28004.1-2021, demonstrating promising industrialization prospects. Attached Figure Description

[0031] Figure 1 This shows a cross-sectional schematic diagram of the layered structure of the absorber core in Embodiment 1 of the present invention; d3 represents the thickness of the third absorber layer; Figure 2 This is a top view of the first absorption layer in Embodiment 1 of the present invention; h represents the depth of the flow-guiding groove, and w represents the width of the flow-guiding groove; Figure 3 The diagram shows an enlarged cross-sectional view of the three-dimensional liquid reservoir in Embodiment 1 of the present invention; D represents the diameter of the three-dimensional liquid reservoir, and δ represents the wall thickness of the three-dimensional liquid reservoir. Figure 4 A cross-sectional schematic diagram of the integral composite structure of the absorber core in Embodiment 1 of the present invention is shown; Among them, 100 is the first absorbent layer; 110 is the wavy flow-guiding groove; 200 is the second absorbent layer; 210 is the three-dimensional liquid storage bladder; 211 is the porous bladder wall; 212 is the internal cavity; 220 is the swollen state; 221 is the inter-bladder channel; 300 is the third absorbent layer; and 400 is the biodegradable microporous membrane. Detailed Implementation

[0032] The following examples are used to illustrate preferred embodiments of the invention. Those skilled in the art will understand that the techniques disclosed in the examples represent techniques discovered by the inventors that can be used to implement the invention, and therefore can be considered preferred embodiments for implementing the invention. However, those skilled in the art should understand from this specification that many modifications can be made to the specific embodiments disclosed herein, still yielding the same or similar results, without departing from the spirit or scope of the invention.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains, and all materials disclosed herein are incorporated herein by reference. Many equivalent techniques of specific embodiments of the invention described herein will be recognized or can be understood by those skilled in the art through conventional experimentation. These equivalents will be included in the claims.

[0034] The technical solution of this application will be further described in detail below with reference to specific embodiments.

[0035] Example 1: Structure of the Absorber Core This embodiment provides a fully bio-based absorbent core based on a seaweed fiber gradient density structure, which, from top to bottom along the thickness direction, includes a first absorbent layer 100, a second absorbent layer 200, and a third absorbent layer 300, as follows: Figure 1 As shown. The specific structure of each layer is as follows: (1) First absorption layer In the first absorber layer 100, the mass ratio of seaweed fiber to polylactic acid fiber is (1:3) to (3:7). The seaweed fiber has a denier of 1.0-2.0 D and a length of 5-6 mm; the polylactic acid fiber has a denier of 1.2-1.8 D and a length of 7-8 mm. The seaweed fiber is modified with silver loading, and the loading of silver nanoparticles is 0.1-0.5% of the mass of the seaweed fiber, with an average particle size of 10-50 nm.

[0036] The first absorbent layer 100 has a basis weight of 30-45 gsm, a thickness of 1.5-2.0 mm, and a porosity of 75-90%. The surface of the first absorbent layer is provided with wavy flow-guiding grooves along its longitudinal direction. The depth of the flow-guiding grooves is 0.3-0.8 mm, the width is 2-5 mm, and the spacing between adjacent flow-guiding grooves is 8-15 mm.

[0037] (2) Second absorption layer In the second absorbent layer 200, the mass ratio of seaweed fiber to polylactic acid fiber is (1-4):1. The seaweed fiber has a denier of 2.5-4.5 D and a length of 6-8 mm; the polylactic acid fiber has a denier of 2.0-3.0 D and a length of 8-10 mm.

[0038] The second absorbent layer 200 contains uniformly distributed three-dimensional reservoirs 210 made of calcium alginate fibers, with a distribution density of 10-30 reservoirs per square centimeter. The three-dimensional reservoirs 210 are hollow spherical structures with a diameter of 0.5-1.5 mm and a wall thickness of 0.05-0.15 mm.

[0039] The second absorbent layer 200 has a basis weight of 100-120 gsm, a thickness of 1.2-1.8 mm, and a porosity of 50-75%.

[0040] (3) Third absorption layer In the third absorber layer 300, the mass ratio of seaweed fiber to polylactic acid fiber is (8-15):1. The seaweed fiber has a denier of 4.0-6.0 D and a length of 8-10 mm; the polylactic acid fiber has a denier of 3.0-4.5 D and a length of 8-10 mm. The seaweed fiber is modified by grafting polyhexamethylene guanidine salt, with a grafting amount of 0.5-2.0% of the seaweed fiber mass.

[0041] The third absorbent layer 300 has a basis weight of 55-65 gsm, a thickness of 0.3-0.8 mm, and a porosity of 25-50%.

[0042] The bottom surface of the third absorbent layer 300 is coated with a biodegradable microporous film 400. The biodegradable microporous film 400 is made of polylactic acid and polybutylene adipate terephthalate blended at a mass ratio of 1:(1-3), with a thickness of 0.015-0.03 mm, a micropore diameter of 0.5-2.0 μm, and a porosity of 20-40%.

[0043] Example 2: Preparation of a three-dimensional liquid reservoir A 3% sodium alginate solution was dripped into a 2% calcium chloride coagulation bath at a flow rate of 1.0 mL / min using a micro-injection pump to form calcium alginate gel microspheres. The gel microspheres were held in the coagulation bath for 45 min to allow the cross-linking reaction to proceed fully. After removal, the gel microspheres were washed three times with deionized water and freeze-dried at -30°C for 36 h to obtain porous hollow calcium alginate microspheres, which are the three-dimensional liquid reservoir 400. Figure 3 As shown, it includes a porous bladder wall 211 and an internal cavity 212.

[0044] The obtained calcium alginate hollow microspheres are regular spherical in shape. The calcium alginate hollow microspheres are mixed with the fiber raw material of the second absorbent layer in a certain proportion. The microspheres are evenly distributed in the fiber web of the second absorbent layer by airflow web forming process, with a distribution density of 10-30 microspheres per square centimeter.

[0045] The three-dimensional liquid reservoir 400 expands in volume and swells after absorbing liquid 210, as shown in the image. Figure 4 As shown, multiple liquid reservoirs come into contact with each other after absorbing liquid, forming a liquid conduction channel, namely the inter-capsule channel 221, which is a three-dimensional interconnected porous network.

[0046] Example 3: Preparation of Silver-Loaded Algae Fibers Seaweed fibers were immersed in a 0.02 mol / L silver nitrate solution for 45 min. The immersed seaweed fibers were then irradiated under ultraviolet light (254 nm wavelength, 30 W power) for 60 min, causing silver ions to be reduced to silver nanoparticles and deposited on the fiber surface. The silver-loaded seaweed fibers were washed three times with deionized water and dried at 55°C.

[0047] Nanoparticles of silver were uniformly distributed on the surface of the seaweed fiber, with a particle size ranging from 20 nm to 40 nm and an average particle size of 30 nm. Inductively coupled plasma mass spectrometry (ICP-MS) determined the silver content in the silver-loaded seaweed fiber to be 0.31 wt%, which is basically consistent with the designed loading. Silver ion leaching tests showed that after soaking in physiological saline at 37°C for 24 hours, the silver ion leaching rate of the silver-loaded seaweed fiber was 0.08 mg / L, far below the limit specified in GB / T 43631-2023.

[0048] Example 4: Preparation of polyhexamethylene guanidine salt grafted seaweed fiber Seaweed fibers were impregnated in a 1.0% polyhexamethylene guanidine salt solution, and the pH was adjusted to 8.5 with 0.1 mol / L sodium hydroxide solution. The reaction was carried out at 50°C for 3 hours. After the reaction was completed, the fibers were removed, washed with deionized water until neutral, and dried at 55°C.

[0049] Infrared spectroscopy analysis revealed a C=N stretching vibration peak at 1650 cm⁻¹ and an NH bending vibration peak at 1550 cm⁻¹ in the grafted seaweed fibers, indicating successful grafting of polyhexamethylene guanidine salt onto the seaweed fiber surface. The Kjeldahl nitrogen determination method showed that the grafting amount of polyhexamethylene guanidine salt was 0.98 wt%, which was basically consistent with the designed grafting amount. Antibacterial zone experiments showed that the grafted seaweed fibers exhibited inhibition zone diameters of 12 mm and 14 mm against *Escherichia coli* and *Staphylococcus aureus*, respectively, demonstrating significantly better antibacterial effects than unmodified seaweed fibers.

[0050] Example 5: Preparation of the Absorber Core The preparation method of the absorber core is as follows: Step 1: Preparation of the first absorption layer Silver-loaded seaweed fibers and polylactic acid fibers were mixed at a mass ratio of 2:8 and then formed into a fiber web using an airflow web-forming device. The airflow web-forming device used was an Airlay type airflow web-forming machine manufactured by Autofar GmbH, Germany. The airflow velocity was 15 m / s, the fiber conveying speed was 10 m / s, the web width was 600 mm, and the web-forming speed was 12 m / min.

[0051] The fiber web is fed into a hot air bonding machine for bonding. The hot air bonding machine is an Andritz model manufactured by Andritz GmbH of Austria, with a hot air temperature of 128℃, an air velocity of 12m / s, and a bonding time of 5 seconds. After bonding, the fiber web is formed on its surface using a hot press molding device, creating wavy guide grooves 110, such as... Figure 2 As shown. The hot pressing molding equipment uses a self-made embossing device. The surface of the embossing roller is set with wavy raised patterns. The hot pressing temperature is 108℃, the hot pressing pressure is 0.3MPa, and the molding speed is 8m / min.

[0052] Step 2: Preparation of the second absorption layer Ordinary seaweed fiber and polylactic acid fiber were mixed at a mass ratio of 6:4, and calcium alginate hollow microspheres (12% of the total fiber mass) were added simultaneously. The mixture was then used to form a fiber web through an airflow web-forming device. The airflow velocity for web forming was 12 m / s, the fiber conveying speed was 8 m / s, and the web-forming speed was 10 m / min.

[0053] The fiber web is pre-compressed at a pressure of 0.1 MPa. The pre-compressed fiber web is then fed into a hot air bonding machine for bonding at a temperature of 132°C, a wind speed of 14 m / s, and a bonding time of 8 seconds.

[0054] Step 3: Preparation of the third absorption layer Polyhexamethylene guanidine salt-grafted seaweed fiber and polylactic acid fiber were mixed at a mass ratio of 9:1 and formed into a fiber web using a wet web forming machine. The wet web forming machine used was a Voith type wet web forming machine manufactured by Voith GmbH, Germany, with a fiber slurry concentration of 0.3%, a web speed of 8 m / min, and a web width of 600 mm.

[0055] The fiber web formed by wet spinning is dehydrated and dried before being fed into a hot press for hot pressing and shaping. The hot press is a Dieffenbacher type hot press manufactured by Dieffenbacher GmbH, Germany, with a hot pressing temperature of 140℃, a hot pressing pressure of 0.8MPa, and a hot pressing time of 30 seconds.

[0056] Step 4: Composite of biodegradable microporous membranes Polylactic acid (PLA) and polybutylene adipate terephthalate (PEG) were blended and granulated at a mass ratio of 4:6, and then extruded into a film using a casting extrusion machine at 190°C. The casting extrusion machine was a Reifenhauser type manufactured by Reifenhauser AG, Germany, with a die gap of 0.5 mm and an extrusion speed of 15 m / min. The extruded film was then subjected to longitudinal and transverse stretching to form a microporous structure. The longitudinal stretching ratio was 2.5, the transverse stretching ratio was 3.0, and the stretching temperature was 60°C.

[0057] The microporous film was bonded to the third absorber layer by hot pressing at a temperature of 125°C, a pressure of 0.3 MPa, and a speed of 10 m / min.

[0058] Step 5: Multi-layer composite and finished product molding The first, second, and third absorbent layers are stacked from top to bottom and fed into a hot air bonding machine for overall lamination. The hot air bonding temperature is 130℃, the air velocity is 12m / s, and the bonding time is 8 seconds, causing the polylactic acid fibers at the interfaces between the layers to melt and bond, forming an integrated absorbent core. The laminated absorbent core is then cut to a predetermined size to obtain the finished absorbent core.

[0059] Finished absorber core performance test: The absorber core prepared above was subjected to performance testing according to the GB / T 28004.1-2021 standard. The test results are as follows:

[0060] The antibacterial performance test was conducted according to GB / T 20944.3-2008 standard, and the test results are as follows:

[0061] The biodegradability test was conducted in accordance with the GB / T 19277.1-2011 standard. After 90 days of testing under composting conditions, the biodegradability rate of the absorbent core was 92%, which meets the requirements for fully biodegradable materials.

[0062] Example 6 This embodiment is basically the same as embodiment 5, except that the material ratios and structural parameters of each layer are different, as detailed below: First absorbent layer: seaweed fiber and polylactic acid fiber are mixed at a mass ratio of 1:9. The seaweed fiber has a denier of 1.0D, a basis weight of 25gsm, a thickness of 1.2mm, a porosity of 88%, and a flow channel groove depth of 0.3mm, a width of 2mm, and a spacing of 10mm.

[0063] Second absorbent layer: seaweed fiber and polylactic acid fiber are mixed in a mass ratio of 4:6. The seaweed fiber has a denier of 2.5D, a three-dimensional liquid storage bladder distribution density of 15 per square centimeter, a weight of 90 gsm, a thickness of 1.2 mm, and a porosity of 70%.

[0064] The third absorbent layer is a mixture of seaweed fiber and polylactic acid fiber in a mass ratio of 8:2. The seaweed fiber has a denier of 4.0D, a basis weight of 45gsm, a thickness of 0.4mm, and a porosity of 42%.

[0065] The absorbent core prepared in this embodiment also exhibits good absorption and antibacterial properties. The initial absorption rate is 22 seconds, the initial reabsorption amount is 1.5g, the total absorption amount is 580g, and the antibacterial rate (8 hours) against Escherichia coli is 98.5%. Due to the relatively low seaweed fiber content, this embodiment is lower in cost and suitable for low-cost products.

[0066] Example 7 This embodiment is basically the same as embodiment 5, except that the material ratios and structural parameters of each layer are different, as detailed below: First absorbent layer: seaweed fiber and polylactic acid fiber are mixed in a mass ratio of 3:7. The seaweed fiber has a denier of 2.0D, a basis weight of 45gsm, a thickness of 2.2mm, a porosity of 80%, and a channel groove depth of 0.8mm, a width of 4mm, and a spacing of 15mm.

[0067] Second absorbent layer: seaweed fiber and polylactic acid fiber are mixed in a mass ratio of 7:3. The seaweed fiber has a denier of 4.5D, a three-dimensional liquid storage bladder distribution density of 25 per square centimeter, a weight of 140 gsm, a thickness of 1.8 mm, and a porosity of 55%.

[0068] The third absorbent layer is a mixture of seaweed fiber and polylactic acid fiber at a mass ratio of 12:1. The seaweed fiber has a denier of 6.0D, a basis weight of 75gsm, a thickness of 0.7mm, and a porosity of 28%.

[0069] The absorbent core prepared in this embodiment has a high seaweed fiber content, resulting in superior absorption performance. The initial absorption rate is 15 seconds, the initial reabsorption is 0.8g, and the total absorption is 720g. It also exhibits a 99.8% inhibition rate against E. coli after 8 hours. This solution is suitable for high-end product applications requiring high absorption and antibacterial performance.

[0070] The material safety and standard compliance of the absorbent core of the present invention were verified, and the results are as follows: (a) Raw material safety verification Tests were conducted according to GB 43631-2023 Basic Safety Technical Specifications for Paper Products for Infants and Children:

[0071] (II) Verification of health indicators Tests were conducted according to GB 15979-2024, "Hygienic Requirements for Disposable Sanitary Products".

[0072] (III) Performance Index Verification Tests were conducted according to GB / T 28004.1-2021 Diapers Part 1: Baby Diapers:

[0073] The key design features and performance advantages of the absorber core of this invention are analyzed as follows: (1) By constructing a triple gradient distribution of material ratio, fiber denier, and porosity in the thickness direction: the seaweed fiber mass percentage in the first absorbent layer is only 10% to 30%, using fine denier fibers of 1.0D to 2.0D, with a porosity as high as 75% to 90%, forming a fluffy porous structure, allowing liquid to pass through quickly without accumulating on the surface; the seaweed fiber mass percentage in the second absorbent layer is increased to 40% to 70%, using medium denier fibers of 2.5D to 4.5D, with a porosity controlled at 50% to 75%, forming a medium density layer. An equal-density absorption network enables rapid absorption and initial storage of the liquid. The third absorption layer contains 80% to 95% seaweed fiber by mass, using coarse denier fibers of 4.0D to 6.0D, reducing the porosity to 25% to 50% to form a dense water-locking barrier. At the same time, a biodegradable microporous membrane is composited on the bottom surface as the final anti-reverse osmosis layer. This gradient design allows the functions of each layer to precisely match the needs of the liquid at different stages of transport in the core: the surface layer conducts water quickly, the middle layer absorbs water strongly, and the bottom layer locks water firmly. The three work together to achieve a unity of rapid absorption and water retention.

[0074] (2) Three-dimensional liquid storage bladders composed of hollow calcium alginate microspheres are uniformly distributed in the second absorbent layer. The hollow spherical structure of the three-dimensional liquid storage bladder itself has a large liquid storage space. After absorbing liquid, the volume increases to 2 to 5 times the original volume, but the bladder itself maintains its complete shape and will not swell and break like SAP particles. The porous bladder wall allows liquid to enter the bladder quickly. The calcium alginate gel of the bladder wall has high hygroscopicity and can lock the liquid firmly in the bladder. After absorbing liquid, multiple liquid storage bladders come into contact with each other to form a three-dimensional interconnected porous network, i.e., inter-bladder channels, which enhances the conductivity of liquid in the core and will not block the channels like SAP. When the liquid storage bladder is under pressure, it buffers the external pressure through elastic deformation to prevent the liquid from being squeezed out and backflowing. After the pressure is released, the bladder rebounds and restores its liquid storage capacity. This structural design enables the absorbent core to maintain structural integrity and stable absorption performance after multiple liquid absorptions.

[0075] (3) A functional zone conduction system combining longitudinal conduction channels and transverse diffusion networks is constructed within the core to actively guide the liquid conduction path: In terms of longitudinal conduction channels, the bottom fibers of the wavy guide grooves on the surface of the first absorbent layer are compacted during hot pressing, forming a preferential conduction channel with stronger capillary effect. The conduction speed of the liquid along the groove direction is 3 to 5 times that of the surrounding non-compacted area, enabling the liquid to be quickly distributed to the middle and end areas of the core, avoiding liquid accumulation in local areas; In terms of transverse diffusion networks, the three-dimensional liquid storage bladders distributed in the second absorbent layer swell after absorbing liquid, and adjacent bladders contact each other to form a three-dimensional interconnected network, enabling the liquid to diffuse laterally into the core through the capillary channels between the bladders, achieving uniform distribution of the liquid in the width direction of the core. The conduction path is longitudinal first and then transverse, allowing the liquid to fully utilize the overall absorption capacity of the core and avoiding side leakage and backflow caused by local saturation.

[0076] (4) A three-layer gradient antibacterial scheme is adopted in the thickness direction of the absorbent core: The first absorbent layer uses silver-loaded nanoparticles loaded on the surface of seaweed fibers for antibacterial purposes. The particle size of the silver-loaded nanoparticles is 10nm to 50nm, and the loading amount is 0.1% to 0.5%. It can quickly kill bacteria by destroying the bacterial cell membrane structure at the first moment of liquid contact, and inhibit the reproduction of bacteria on the surface of the core. The antibacterial effect of the second absorbent layer is brought by the alginate polysaccharide of the seaweed fiber itself. The alginate polysaccharide competes with the calcium ions on the surface of the bacterial cell membrane for binding sites, destroys the calcium ion balance of bacteria, and inhibits bacterial growth. The content of alginate polysaccharide in the fiber is maintained at 8% to 15%, and it is continuously released during the liquid absorption process to achieve long-term antibacterial effect. The third absorbent layer uses polyhexamethylene guanidine salt grafted on the surface of seaweed fibers for antibacterial purposes. The grafting amount of polyhexamethylene guanidine salt is 0.5% to 2.0%. It is bound to the carboxyl groups on the surface of seaweed fibers through ionic bonds. It is not easily washed away by the liquid and has low solubility. It forms the final barrier at the bottom of the core to prevent bacteria from penetrating the core. The three layers of antibacterial action work in a relay-like fashion over time: the first layer rapidly kills bacteria, the second layer continuously inhibits bacterial growth, and the third layer provides a long-lasting barrier. They also complement each other in a spatial fashion: the surface layer inhibits bacterial growth, the middle layer inhibits the growth of bacteria that have already entered the environment, and the bottom layer blocks bacterial penetration, achieving a long-lasting antibacterial effect throughout the entire pathway and all time period.

[0077] (5) Through the synergistic effect of thermal bonding crosslinking points and fiber winding structure, an anti-swelling network is constructed, effectively suppressing structural changes caused by swelling: Regarding thermal bonding crosslinking points, the mass percentage of polylactic acid fiber in each layer decreases from 70% to 90% in the first absorption layer to 5% to 20% in the third absorption layer, forming a stable three-dimensional network skeleton during hot air bonding. When the seaweed fiber absorbs water and swells, these crosslinking points limit the macroscopic deformation of the fiber network, preventing significant changes in the overall size of the core. Regarding the fiber winding structure, by controlling the airflow velocity (10m / s to 20m / s) and fiber transport speed (5m / s to 12m / s) during network formation, the seaweed fiber and polylactic acid fiber form an intertwined network structure during deposition. When the seaweed fiber swells, its diameter increases and its length shortens, but due to the intertwining with the polylactic acid fiber, the swelling stress is dispersed throughout the fiber network, avoiding fiber network rupture caused by local stress concentration. This anti-swelling design, which combines point (crosslinking points) and surface (winding network), allows the core to maintain structural integrity and stable absorption performance even after multiple liquid absorptions.

[0078] (6) Functional modification of seaweed fiber: First, silver loading modification: nano-silver particles are loaded onto the surface of seaweed fiber by ultraviolet light reduction method, giving the fiber a rapid bactericidal function; the nano-silver particles are firmly bonded to the surface of seaweed fiber and are not easy to fall off, and the silver ion dissolution is less than 0.1 mg / L, far below the national standard limit, achieving a balance between safety and functionality. Second, polyhexamethylene guanidine salt grafting modification: polyhexamethylene guanidine salt is grafted onto the surface of seaweed fiber through ionic cross-linking reaction to form ionic bonds; compared with physical adsorption, the ionic bond binding method makes the antibacterial agent less likely to be washed away by liquid, significantly reducing the dissolution rate and greatly improving the antibacterial durability; polyhexamethylene guanidine salt interacts with the negative charge on the surface of bacterial cell membrane through positive charge, destroying the cell membrane structure, achieving broad-spectrum antibacterial effect, and has extremely low skin irritation. Multifunctional modification multiplies the performance of a single material.

[0079] (7) Good compatibility of the preparation process with existing production lines: By controlling the air velocity (10m / s to 20m / s) and fiber conveying speed (5m / s to 12m / s) during the web formation process, the seaweed fiber and polylactic acid fiber form a uniform mixed fiber web, avoiding the problem of uneven web formation caused by differences in fiber length and fineness. In view of the high temperature resistance of seaweed fiber, the hot air bonding temperature is controlled within the range of 120℃ to 140℃, so that the skin of polylactic acid fiber partially melts to form bonding nodes, while the seaweed fiber maintains its intact shape. Selective melt bonding can ensure the interlayer bonding strength and avoid thermal damage to seaweed fiber. For the third absorbent layer with a high seaweed fiber content, a combination of wet web formation and hot pressing is adopted. The wet web formation process forms a uniform fiber deposition layer, avoiding the problem of uneven dispersion that may occur in air-laid web formation under high concentration of seaweed fiber conditions; then, a high density structure is obtained by hot pressing, while ensuring the interlayer bonding strength. The three-layer fiber web is laid out sequentially and then bonded together with hot air in one go, avoiding multiple processing steps and interface defects caused by separate bonding, simplifying the process and improving production efficiency.

[0080] All materials used in the absorbent core of this invention comply with the requirements for raw material safety in GB 43631-2023 Basic Safety Technical Specifications for Paper Products for Infants and Children: seaweed fiber is a natural polysaccharide fiber derived from edible seaweed; polylactic acid fiber is a bio-based biodegradable polyester; polyhexamethylene guanidine salt is a low-toxicity cationic polymer grafted onto the fiber surface via ionic bonding, resulting in low leaching; silver nanoparticles are loaded onto the fiber surface, with silver ion leaching below 0.1 mg / L, far below the national standard limit.

[0081] Meanwhile, the absorbent core utilizes entirely bio-based materials: seaweed fiber is derived from renewable seaweed resources; seaweed farming requires no arable land, freshwater, or chemical fertilizers and pesticides, offering natural sustainability advantages. Polylactic acid fiber is derived from lactic acid produced by fermenting starch from plants such as corn and sugarcane, and is a bio-based biodegradable material. Polybutylene adipate terephthalate (PEG) is a biodegradable polyester that can be completely decomposed into carbon dioxide and water by microorganisms under composting conditions. The biodegradable microporous membrane also uses a blend of polylactic acid and PEG, exhibiting the same degradation performance as the other materials in the core. This entirely bio-based material system allows the product to completely degrade under industrial composting conditions after use.

[0082] All materials and composite structures meet the hygiene requirements of GB 15979-2024 Hygiene Requirements for Disposable Sanitary Products, including initial contamination bacteria, total bacterial count, coliform bacteria, pathogenic pyogenic bacteria, and total fungal count.

[0083] The absorbent core's absorption rate, rewetting amount, absorbency, and dimensional stability meet the relevant requirements of GB / T28004.1-2021 Diapers Part 1: Baby Diapers. The manufacturing process of this invention is compatible with existing production lines, requires no large-scale equipment modifications, and has a clear and controllable process flow, demonstrating promising industrialization prospects.

[0084] In summary, this invention provides a novel absorbent core solution with excellent performance, feasible process, and safety and environmental friendliness for the field of disposable hygiene products.

[0085] All documents mentioned in this invention are incorporated herein by reference as if each document were individually incorporated by reference. Furthermore, it should be understood that after reading the foregoing teachings of this invention, those skilled in the art can make various alterations or modifications to this invention, and these equivalent forms also fall within the scope defined by this application.

Claims

1. A fully bio-based absorber core based on a gradient density structure of seaweed fibers, characterized in that: The absorbent core comprises, from top to bottom along its thickness, a first absorbent layer, a second absorbent layer, and a third absorbent layer. Each of these layers is composed of a mixture of seaweed fiber and biodegradable thermoplastic fiber. The biodegradable thermoplastic fiber is selected from one or more of polylactic acid fiber, polybutylene succinate fiber, and polybutylene adipate terephthalate fiber. The mass percentage of seaweed fiber in the first, second, and third absorbent layers increases in a gradient. The mass percentage of seaweed fiber in the first absorbent layer is 10-30%, in the second absorbent layer it is 40-70%, and in the third absorbent layer it is 80-95%. The mass percentage of biodegradable thermoplastic fiber in each layer decreases as the seaweed fiber content increases.

2. The all-bio-based absorbent core based on a seaweed fiber gradient density structure according to claim 1, characterized in that: The mass ratio of seaweed fiber to biodegradable thermoplastic fiber in the first absorbent layer is (1:3) to (3:7), the denier of the seaweed fiber is 1.0-2.0 D, and the denier of the biodegradable thermoplastic fiber is 1.2-1.8 D.

3. The all-bio-based absorbent core based on a seaweed fiber gradient density structure according to claim 2, characterized in that: The surface of the first absorption layer is provided with multiple wavy flow-guiding grooves along its longitudinal direction. The depth of the flow-guiding grooves is 0.3-0.8 mm, the width is 2-5 mm, and the spacing between adjacent flow-guiding grooves is 8-15 mm.

4. The all-bio-based absorbent core based on a seaweed fiber gradient density structure according to claim 1, characterized in that: The first absorbent layer contains a first antibacterial factor, which is silver-loaded nanoparticles with a particle size of 10-50 nm. The silver-loaded nanoparticles are loaded on the surface of seaweed fibers, and the loading amount is 0.1-0.5% of the mass of the seaweed fibers.

5. The fully bio-based absorbent core based on a seaweed fiber gradient density structure according to claim 1, characterized in that: The mass ratio of seaweed fiber to biodegradable thermoplastic fiber in the second absorbent layer is (1-4):1, the denier of the seaweed fiber is 2.5-4.5 D, and the denier of the biodegradable thermoplastic fiber is 2.0-3.0 D.

6. The fully bio-based absorbent core based on a seaweed fiber gradient density structure according to claim 1, characterized in that: The alginate polysaccharide content of the seaweed fiber in the second absorbent layer is maintained at 8-15%.

7. The all-bio-based absorbent core based on a seaweed fiber gradient density structure according to claim 5, characterized in that: The second absorbent layer contains three-dimensional reservoirs made of calcium alginate fibers.

8. The all-bio-based absorbent core based on a seaweed fiber gradient density structure according to claim 7, characterized in that: The three-dimensional liquid storage bladder is a hollow spherical or ellipsoidal structure with a diameter of 0.5-1.5 mm and a wall thickness of 0.05-0.15 mm.

9. The all-bio-based absorber core based on a seaweed fiber gradient density structure according to claim 1, characterized in that: The mass ratio of seaweed fiber to biodegradable thermoplastic fiber in the third absorbent layer is (8:1) to (15:1), the denier of the seaweed fiber is 4.0-6.0 D, and the denier of the biodegradable thermoplastic fiber is 3.0-4.5 D.

10. The all-bio-based absorbent core based on a seaweed fiber gradient density structure according to claim 9, characterized in that: The surface of the seaweed fibers in the third absorbent layer is grafted with polyhexamethylene guanidine salt, and the amount of polyhexamethylene guanidine salt grafted is 0.5-2.0% of the mass of the seaweed fibers.

11. The fully bio-based absorbent core based on a seaweed fiber gradient density structure according to claim 1, characterized in that: The bottom surface of the third absorbent layer is coated with a biodegradable microporous film, which has a thickness of 0.015-0.030 mm, a pore size of 0.5-2.0 μm, and a porosity of 20-40%.

12. A method for preparing a fully bio-based absorbent core according to any one of claims 1-11, characterized in that, Includes the following steps: S1. Raw material preparation: Fiber raw material preparation: Opening treatment is carried out on seaweed fiber raw materials and biodegradable thermoplastic fiber raw materials; Three-dimensional liquid storage bladders, silver-loaded seaweed fibers, polyhexamethylene guanidine salt-grafted seaweed fibers, and biodegradable microporous membranes were prepared for use. S2. Preparation of the first absorption layer: The silver-loaded seaweed fiber and the biodegradable thermoplastic fiber raw material are mixed in a certain proportion and formed into a fiber web by an airflow web forming device. The airflow velocity for web forming is 12-18 m / s, and the fiber conveying speed is 8-12 m / s. The fiber web is then fed into a hot air bonding device for bonding. The hot air temperature is 120-135 ℃, the air velocity is 10-15 m / s, and the bonding time is 3-8 s. After bonding, the fiber web is formed into a wavy flow-guiding groove on its surface by a hot pressing molding device. The hot pressing temperature is 100-115 ℃, the hot pressing pressure is 0.2-0.4 MPa, and the molding speed is 5-10 m / min. S3, Prepare the second absorber layer The seaweed fiber raw material and the biodegradable thermoplastic fiber raw material are mixed in a certain proportion, and the three-dimensional liquid storage bladder, accounting for 5-15% of the total fiber mass, is added. The mixture is then formed into a fiber web using an airflow web forming device with an air velocity of 10-15 m / s and a fiber conveying speed of 6-10 m / s. The fiber web is then pre-compressed with a pre-compression pressure of 0.05-0.15 MPa. The pre-compressed fiber web is then fed into a hot air bonding device for bonding, with a hot air temperature of 125-140℃, an air velocity of 12-18 m / s, and a bonding time of 5-10 s. S4. Preparation of the third absorption layer The polyhexamethylene guanidine salt-grafted seaweed fiber is mixed with the biodegradable thermoplastic fiber raw material in a certain proportion, and a fiber web is formed by wet web forming equipment. The fiber slurry concentration is 0.1-0.5%, and the web forming speed is 5-10 m / min. The fiber web formed by wet web forming is dehydrated and dried, and then sent to a hot press for hot pressing and shaping. The hot pressing temperature is 130-150℃, and the hot pressing pressure is 0.5-1.0 MPa. S5, Composite Biodegradable Microporous Film The biodegradable microporous film and the third absorbent layer are bonded together by hot pressing at a temperature of 120-130°C and a pressure of 0.2-0.4 MPa. S6, Multilayer Composite The first absorbent layer, the second absorbent layer, and the third absorbent layer are stacked in order from top to bottom and sent into a hot air bonding equipment for overall composite bonding. The hot air temperature is 125-135℃, the wind speed is 10-15 m / s, and the bonding time is 5-10 s, so that the polylactic acid fibers at the interface between the layers melt and bond together to form an integrated absorbent core. S7, Finished product molding The composite absorbent core is cut to a predetermined size to obtain the finished product.

13. The method for preparing a fully bio-based absorbent core based on a seaweed fiber gradient density structure according to claim 12, characterized in that, The preparation process of the three-dimensional liquid reservoir is as follows: a sodium alginate solution with a mass percentage of 2-5% is dripped into a calcium chloride coagulation bath with a mass percentage of 1-3% using a micro-injection pump at a flow rate of 0.5-2 mL / min to form calcium alginate gel microspheres; the gel microspheres are kept in the coagulation bath for 30-60 min to allow the cross-linking reaction to proceed fully; after the gel microspheres are removed, they are washed with water 3-5 times and freeze-dried at a temperature of -20℃ to -40℃ for 24-48 hours to obtain a porous three-dimensional liquid reservoir.

14. The method for preparing a fully bio-based absorbent core based on a seaweed fiber gradient density structure according to claim 12, characterized in that, The preparation process of the silver-loaded seaweed fiber is as follows: the seaweed fiber is immersed in a silver nitrate solution with a concentration of 0.01-0.05 mol / L for 30-60 min, and the immersed seaweed fiber is irradiated under ultraviolet light for 30-90 min with an ultraviolet wavelength of 254 nm and a power of 20-50 W to reduce silver ions into nano-silver particles and deposit them on the fiber surface; the silver-loaded seaweed fiber is washed with water 3-4 times and dried at a temperature of 50-60℃.

15. The method for preparing a fully bio-based absorbent core based on a seaweed fiber gradient density structure according to claim 12, characterized in that, The preparation process of the polyhexamethylene guanidine salt-grafted seaweed fiber is as follows: the seaweed fiber is immersed in a polyhexamethylene guanidine salt solution with a concentration of 0.5-2.0%, the pH is adjusted to 8.0-9.0, and the reaction is carried out at a temperature of 40-60℃ for 2-4 hours; after the reaction is completed, the fiber is taken out, washed with water until neutral, and dried at a temperature of 50-60℃ to obtain the polyhexamethylene guanidine salt-grafted seaweed fiber.

16. The method for preparing a fully bio-based absorbent core based on a seaweed fiber gradient density structure according to claim 12, characterized in that, The preparation process of the biodegradable microporous film is as follows: polylactic acid and polybutylene adipate terephthalate are blended and granulated at a mass ratio of (3:7)-(5:5), and extruded into a film at a temperature of 180-200℃ through a casting extrusion device. The film is then stretched longitudinally and laterally to form a microporous structure, with a longitudinal stretching ratio of 2.0-3.0 and a lateral stretching ratio of 2.5-3.5.

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