Biodegradable sanitary towel with polylactic acid as main component

Abstract

The invention discloses a biodegradable sanitary towel with polylactic acid as a main component. The biodegradable sanitary towel comprises a degradable core body, and the degradable core body comprises a surface layer, an absorption core layer and a bottom layer; the surface layer is a polylactic acid fiber non-woven fabric; the polylactic acid fiber non-woven fabric is a polylactic acid fiber spunlace non-woven fabric, a polylactic acid fiber hot air non-woven fabric or a polylactic acid spunbond non-woven fabric; the absorption core layer comprises an upper layer, a middle layer and a lower layer; the upper layer and the lower layer are made of polylactic acid fiber non-woven fabrics, and the middle layer is a mixture composed of polylactic acid two-component fibers and super absorbent resin. And the bottom layer is a degradable impermeable film which is a PHA modified polylactic acid film. The composite material has natural weak acidity and natural antibacterial activity, can create a weak-acidity antibacterial microenvironment for people, is skin-friendly, environment-friendly and healthy, and is an ideal selected material for disposable hygienic products. The natural antibacterial agent has the functions of natural bacteriostasis, weak acidity and the like, and is biodegradable.

Description

Technical Field

[0001] The invention relates to a biodegradable sanitary napkin with polylactic acid as the main component, belonging to the technical field of sanitary napkins. Background Art

[0002] The sanitary napkins currently sold on the market are non-degradable and contain a large amount of plastic components, such as PE / PP non-woven polymer absorbent resin (SAP) and plastic outer packaging. These plastic components are difficult to degrade in the natural environment. Some take 250 to 800 years, or may never decompose. Each sanitary napkin contains about the equivalent of 4 plastic bags of plastic. Over time, these plastics will gradually fragment and decompose into microparticles, flowing into the soil, groundwater or ocean, causing microplastic pollution. Microplastics are potentially harmful to soil, water quality and marine life.

[0003] Data show that the global market size of feminine hygiene products (including sanitary napkins) is expected to be US$50.35 billion in 2024. It is expected that the global feminine hygiene products market will grow at a compound annual growth rate of 6.1% between 2024 and 2029. The huge consumption requires the promotion of research and development and marketable production of biodegradable sanitary napkins to avoid harm to the environment and benefit mankind.

[0004] Existing reports on the preparation methods of degradable sanitary napkins are difficult to produce with existing equipment, and the processing cost is very high, which cannot even reach the laboratory research and development scale, let alone industrial production, and thus it is difficult to reach the commercial scale. Therefore, it is very necessary to develop and produce degradable sanitary napkins that can be processed on existing equipment, can achieve economies of scale, are moderately cost-effective, and have good functionality. Summary of the invention

[0005] The purpose of the present invention is to provide a biodegradable sanitary napkin with polylactic acid as the main component, which has biodegradability.

[0006] To solve the above technical problems, the purpose of the present invention is achieved as follows:

[0007] The biodegradable sanitary napkin with polylactic acid as the main component involved in the present invention comprises a degradable core body, wherein the degradable core body comprises a surface layer, an absorbent core layer and a bottom layer;

[0008] The surface layer is a polylactic acid fiber nonwoven fabric; the polylactic acid fiber nonwoven fabric is a polylactic acid fiber spunlace nonwoven fabric, a polylactic acid fiber hot air nonwoven fabric or a polylactic acid spunbond nonwoven fabric;

[0009] The absorbent core layer comprises an upper layer, a middle layer and a lower layer; the upper layer and the lower layer are polylactic acid fiber non-woven fabrics, and the middle layer is a mixture of polylactic acid bicomponent fibers and highly absorbent resin;

[0010] The bottom layer is a degradable anti-seepage membrane, and the degradable anti-seepage membrane is a PHA-modified polylactic acid membrane.

[0011] On the basis of the above scheme and as a preferred scheme of the above scheme: the surface layer is a polylactic acid hot air non-woven fabric, and the fiber used is a bicomponent composite polylactic acid fiber; the polylactic acid hot air non-woven fabric comprises an upper polylactic acid fiber net and a lower polylactic acid fiber net; the specification of the bicomponent composite polylactic acid fiber used in the upper polylactic acid fiber net is 1.0-2.0D*38mm, and the specification of the bicomponent composite polylactic acid fiber used in the lower polylactic acid fiber net is 3.0-6.0D*51mm;

[0012] The two-component composite polylactic acid fiber comprises a cortex and a core layer with the same core; the cortex is a low-melting-point polylactic acid component or a modified polylactic acid component; the melting point of the polylactic acid component in the core layer is 160-175°C, and the melting point of the polylactic acid component in the cortex is 118-135°C.

[0013] On the basis of the above scheme and as a preferred scheme of the above scheme: the modified polylactic acid component includes a polylactic acid component and a modified component, and the modified component includes PHA, PBT, PBS, PBAT or PCL biodegradable material.

[0014] On the basis of the above scheme and as a preferred scheme of the above scheme: the modified components are PHA and PBS; and the weight ratio of the polylactic acid component to the modified component is 7-5:5-3.

[0015] On the basis of the above scheme and as a preferred scheme of the above scheme: the content of surface oil in the two-component composite polylactic acid fiber used in the upper polylactic acid fiber net is 0.02-0.1%; the surface oil contains LurolPP-12147 type hydrophilic oil.

[0016] On the basis of the above scheme and as a preferred scheme of the above scheme: the production equipment of the hot air nonwoven fabric of polylactic acid includes two sets of independent opening, mixing and carding systems, the first set is used to prepare the upper polylactic acid fiber web, and the second set is used to prepare the lower polylactic acid fiber web;

[0017] The production of the hot air nonwoven fabric of polylactic acid comprises the following steps:

[0018] 1) The polylactic acid two-component fiber with a specification of 3.0-6.0D*51mm is fed into the second set of opening, mixing, carding and web forming system, fed through the bag opener, and after opening, mixing, carding and random roller randomization, the upper and lower double doffers are used to peel the web to form a lower layer of random fiber web, and the fiber web weight is 10.5-20.5g / m2;

[0019] 2) The polylactic acid bicomponent fibers with specifications of 1.0-2.0D*38mm are fed into the first set of opening, mixing, carding and web forming systems, fed through the bag opener, and after opening, mixing and carding, they are peeled off by upper and lower double doffers and fall on the random fiber web formed by the second system to form an upper fiber web. This system does not contain random rollers and condensation rollers. Instead, the polylactic acid bicomponent fibers are directly stripped by doffers after passing through the carding machine to form a layer of straight-laid web. In the straight-laid web, the angle with the equipment running direction (production direction) is used as a reference. The number of polylactic acid bicomponent fibers arranged in a direction of <20-45° accounts for 70-88% of all fibers in the fiber web, and the gram weight of the straight-laid fiber web is 8.9-15g / m 2 ;

[0020] 3) The upper and lower fiber webs formed above are sent into a flat net hot air penetration oven for heat consolidation. The mesh number of the oven net curtain is 10 meshes, the opening rate is 68%, and the oven is a three-stage oven. The first stage is 100-120°C, the second stage is 120-130°C, and the third stage is 110-120°C. The circulating air volume during heat consolidation is 8200-9000m 3 / h, after leaving the oven and passing through a cooling channel of 5-8 meters, it is wound into a polylactic acid fiber hot air non-woven fabric surface layer with a thickness of 0.2-1mm.

[0021] On the basis of the above scheme and as a preferred scheme of the above scheme: the upper layer and the lower layer are polylactic acid spunlace non-woven fabrics.

[0022] On the basis of the above scheme and as a preferred scheme of the above scheme: the preparation process of the absorbent core layer is as follows:

[0023] First, unwind the lower layer, and spray a layer of a mixture of polylactic acid bicomponent fiber and super absorbent resin on the surface of the lower layer, with a spraying amount of 60-80 g / m2, wherein the ratio of polylactic acid bicomponent fiber to super absorbent resin is 0-2:8-10;

[0024] Then, a layer of a mixture of polylactic acid bicomponent fiber and super absorbent resin is sprayed thereon again, with a spraying amount of 40-50 g / m2, wherein the ratio of polylactic acid bicomponent fiber to super absorbent resin is 5:5;

[0025] Finally, the upper layer is unrolled and placed above the middle layer;

[0026] Then the three-layer composite body is put into the oven for heat consolidation treatment.

[0027] On the basis of the above scheme and as the preferred scheme of the above scheme: the heat reinforcement treatment adopts a two-stage flat mesh oven, each section of the oven is 2 meters long, the hot air penetration temperature entering the first section of the oven is 110-120°C, and the hot air penetration temperature in the second section of the oven is 120-140°C. The running speed in the oven is 15-25 meters / minute, and a three-layer core layer is obtained after exiting the oven, with a gram weight of 150-230 grams / square meter.

[0028] On the basis of the above scheme and as a preferred scheme of the above scheme: the polylactic acid fiber spunlace non-woven fabric used in the upper and lower layers is a single-component polylactic acid fiber, the fiber specification is 1.5-2.0D*38mm, the fiber melting point is 160-175°C, in order to make the core absorb water faster and the liquid is not easy to seep out from the lower layer, the single-component polylactic acid fiber used in the upper layer is hydrophilic, the fiber surface oil content is 0.07-0.09%, the single-component polylactic acid fiber used in the lower layer is water-repellent, the fiber surface oil content is 0.05-0.08%; the polylactic acid fiber spunlace non-woven fabric has a gram weight of 25-50g / m 2 .

[0029] The polylactic acid two-component fiber blended with super absorbent resin is a hydrophilic high-curl eccentric core fiber with a fiber specification of 1.5-3.0D*10mm. The core layer is a high-melting point component with a melting point of 160-175 degrees, and the skin layer is a low-melting point component with a melting point of 118-135 degrees. The mass ratio of the skin layer to the core layer is 4-6:4-6.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1) Natural antibacterial properties

[0032] Polylactic acid fiber is a "man-made natural fiber" made from lactic acid produced by modern biotechnology from non-grain crops, and then through a special polymerization reaction and spinning process. Under normal temperature and humidity conditions, PLA polylactic acid fiber and its products are materials with stable physical properties. Its waste can be degraded into carbon dioxide and water by microbial action in soil or seawater, and then regenerated into crops through plant photosynthesis, entering the large cycle of nature indefinitely and repeatedly. It is a completely degradable biomass fiber.

[0033] The experimental results show that the surface pH value of hot air non-woven fabric, spunlace non-woven fabric and polylactic acid fiber spunbond non-woven fabric made of 100% polylactic acid fiber is between 6-6.5, which is close to the pH value of human skin. It has natural weak acidity and natural antibacterial properties. Disposable items such as sanitary napkins and panty liners made of them can create a weakly acidic antibacterial microenvironment for people. They are skin-friendly, environmentally friendly and healthy, and are ideal materials for disposable sanitary products.

[0034] 2) Softness and comfort

[0035] The absorption layer of the present invention is an absorption material with polylactic acid as the main component. The surface layer and the bottom layer are respectively a hydrophilic polylactic acid fiber spunlace nonwoven fabric and a water-repellent polylactic acid fiber spunlace nonwoven fabric, the super absorbent resin is a biodegradable super absorbent resin, and a highly curled eccentric polylactic acid bicomponent fiber is particularly selected as a dispersion, wrapping and water-conducting fiber. After being heated and shaped in an oven, the eccentric polylactic acid bicomponent fiber shrinks and curls, and the resulting highly curled pores wrap the super absorbent resin and play a role in fixing the super absorbent resin at the same time, without spraying hot melt adhesive to bond and fix the super absorbent resin (hot melt adhesive will reduce the absorption capacity of the super absorbent resin). When the super absorbent resin absorbs water and swells, the highly curled pores of the eccentric polylactic acid bicomponent fiber provide it with sufficient swelling space, and no retardation occurs, which helps it to fully absorb liquid, thereby making full use of its absorption capacity, and reducing the use of the super absorbent resin without affecting the absorption performance, thereby reducing the production cost.

[0036] On the other hand, the surface layer and the bottom layer are respectively hydrophilic polylactic acid fiber spunlace non-woven fabric and water-repellent polylactic acid fiber spunlace non-woven fabric, which are softer and more comfortable than the existing products that use dust-free paper as the surface layer and the bottom layer of the absorbent core layer. At the same time, the strength is further improved to avoid the core layer from being broken.

[0037] 3) Instantaneous moisture absorption and conductivity

[0038] The sanitary napkin prepared by the present invention preferably has a polylactic acid fiber hot air non-woven fabric as the surface layer, which is composed of an upper and lower double-layer fiber web of 100% polylactic acid fiber. The upper layer is a straight-laid fiber web composed of ultrafine 1.0-2.0D*38mm polylactic acid two-component fibers, and the lower layer is a random fiber web composed of 3.0-6.0D*51mm coarse denier polylactic acid fibers. The upper fiber web has the functions of instantaneous absorption and longitudinal flow guidance, and is soft and comfortable to the touch; the lower layer of medium-coarse denier polylactic acid fibers has the functions of single-point single-time hydrophilicity and fast water seepage speed. While quickly draining the liquid conducted down from the upper fiber web, it can also prevent the liquid in the middle absorption layer from seeping back, and keep the upper fiber web dry.

[0039] 4) Feasibility

[0040] The surface layer of the polylactic acid fiber hot air nonwoven fabric, the middle layer of the absorbent core layer with polylactic acid as the main component, and the polylactic acid film modified by PHA of the present invention can be processed and produced on existing production equipment, and can be fully mass-produced. The polylactic acid fiber nonwoven fabric is used as the surface layer, which is antibacterial, deodorizing and not easy to cause allergies. The bottom layer is a modified polylactic acid film, which is soft and extensible, can quickly conduct heat and moisture and has good barrier properties. The core layer is an eccentric polylactic acid two-component fiber and a biodegradable super absorbent resin (the biodegradability of the BC706 type biodegradable super absorbent resin of Formosa Plastics Corporation is 66% (180 days). According to the evaluation standards of EN 13432 and GB / T 20197, the composting degradation rate or biodegradation rate of bio-based care products is ≥60%, which can meet the degradation standard requirements). Therefore, the present invention has natural antibacterial, weak acidity and other functionalities, is biodegradable, and can be fully commercialized on existing equipment, which is of great commercial value. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic structural diagram of the degradable core involved in the present invention;

[0042] Figure 2 This is an electron microscope image of the PHA-modified polylactic acid film;

[0043] Figure 3 It is a cross-sectional view of a concentric polylactic acid bicomponent fiber;

[0044] Figure 4 This is the appearance of the concentric polylactic acid bicomponent fiber;

[0045] Figure 5 is a cross-sectional view of an eccentric polylactic acid fiber;

[0046] Figure 6 It is a longitudinal diagram of the eccentric polylactic acid fiber;

[0047] Figure 7 The degradable sanitary napkin prepared by the present invention is coated with a polylactic acid fiber spunbonded nonwoven fabric;

[0048] Figure 8 yes Figure 5 The expanded diagram of the degradable sanitary napkin;

[0049] Fig. 9 This is a comparison of the degradable sanitary napkin after two weeks of degradation experiment and the initial state;

[0050] Fig.10 This is a comparison of the degradable sanitary napkin after five weeks of degradation experiment and the initial state;

[0051] Fig.11 This is a comparison of the degradable sanitary napkin after ten weeks of degradation experiment and the initial state;

[0052] Fig.12 This is a comparison of the degradable sanitary napkin after twelve weeks of degradation experiment and the initial state;

[0053] Fig.13 This is the result of the biodegradable sanitary napkin after thirteen weeks of degradation experiment.

[0054] The markings in the figure are as follows: 1-surface layer; 2-absorbent core layer; 3-bottom layer; 21-upper layer; 22-middle layer; 23-bottom layer. DETAILED DESCRIPTION

[0055] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0056] Embodiment 1

[0057] like Figure 1 As shown, the biodegradable sanitary napkin with polylactic acid as the main component involved in this embodiment includes a degradable core, and the degradable core includes a surface layer 1, an absorbent core layer 2 and a bottom layer 3; the surface layer 1 is a polylactic acid fiber non-woven fabric; the polylactic acid fiber non-woven fabric is a polylactic acid fiber spunlace non-woven fabric, a polylactic acid fiber hot air non-woven fabric or a polylactic acid spunbond non-woven fabric; the absorbent core layer 2 includes an upper layer 21, a middle layer 22 and a lower layer 23; the upper layer 21 and the lower layer 23 are polylactic acid fiber non-woven fabrics, and the middle layer 22 is a mixture of polylactic acid two-component fibers and super absorbent resin; the bottom layer 3 is a degradable anti-seepage membrane, and the degradable anti-seepage membrane is a PHA modified polylactic acid membrane.

[0058] In this embodiment, the surface layer 1 is selected as a polylactic acid fiber hot air nonwoven fabric. When producing the polylactic acid hot air nonwoven fabric, two sets of independent opening, mixing, combing and web forming systems of hot air nonwoven fabric production equipment are used, one of which is used to process the upper polylactic acid fiber web, and the second is used to process the lower polylactic acid fiber web. The specific process is as follows:

[0059] The polylactic acid two-component fiber with a specification of 3.0D*51mm is fed into the second set of opening, mixing, carding and web forming system, fed through the bag opener, and after opening, mixing, carding and random roller randomization, it is stripped by the upper and lower double doffers to form the lower random fiber web. The fiber web weight is 10.5g / m 2 , which is the lower layer of polylactic acid fiber mesh.

[0060] The polylactic acid bicomponent fiber with the specification of 1.0D*38mm is fed into the first system, fed through the bag opener, and after being opened, mixed, and combed, it is peeled by the upper and lower double doffers and falls on the random fiber web formed by the second system to form an upper fiber web. This system does not contain random rollers and condensation rollers. Instead, the polylactic acid bicomponent fiber is directly peeled by the doffer after passing through the combing machine to form a layer of straight-laid web. In the straight-laid web, the angle with the running direction of the equipment (production direction) is used as a reference. The number of polylactic acid bicomponent fibers arranged in a direction of <20-30° accounts for 70-75% of all fibers in the fiber web. The gram weight of the straight-laid fiber web is 8.9g / m 2 , which is the upper polylactic acid fiber mesh.

[0061] The upper and lower two layers of polylactic acid fiber net formed above are sent into a flat mesh hot air penetration oven for thermal reinforcement. The mesh number of the oven mesh curtain is 10 meshes, the opening rate is 68%, the oven is a three-stage oven, the first stage is 100°C, the second stage is 120°C, and the third stage is 110°C. The circulating air volume during thermal reinforcement is 8200m3 / h. After passing through a 5-meter cooling channel out of the oven, it is wound into a polylactic acid fiber hot air non-woven fabric surface layer with a gram weight of 19.4g / m2 and a thickness of 0.2mm.

[0062] The polylactic acid fiber hot air nonwoven fabric prepared above, the upper and lower polylactic acid fiber nets use the same core type polylactic acid bicomponent fiber, such as Figure 3 and 4 As shown, the core layer is 100% polylactic acid component, and the skin layer includes 100% polylactic acid component and modified polylactic acid component. In order to be able to be batch processed on conventional hot air non-woven fabric production equipment, the skin layer preferably uses a modified polylactic acid component, and the modified components include biodegradable materials such as PHA, PBT, PBS, PBAT, PCL, etc. The preferred modified component in the present invention is PHA+PBS, and the ratio of PLA:PHA+PBS=7:3.

[0063] The absorbent core layer 2 is composed of three layers, the upper layer 21 and the lower layer 23 are both polylactic acid fiber spunlace non-woven fabrics, and the middle layer is a mixture of polylactic acid bicomponent fibers and super absorbent resin, and the production method thereof is as follows:

[0064] First, the lower layer 21 of polylactic acid spunlace nonwoven fabric is unrolled, and a layer of polylactic acid bicomponent fiber and super absorbent resin is sprayed on its surface, with a spraying amount of 60 g / m2, wherein the ratio of polylactic acid bicomponent fiber: super absorbent resin is: 0:10; then a layer of polylactic acid bicomponent fiber and super absorbent resin mixture is sprayed on it again, with a spraying amount of 40 g / m2, wherein the ratio of polylactic acid bicomponent fiber: super absorbent resin is: 5:5; finally, the upper layer of polylactic acid fiber spunlace nonwoven fabric is unrolled as the surface layer of the core. Subsequently, the above three-layer composite body enters the oven together for thermal reinforcement treatment, using a two-stage flat mesh oven, each oven length of 2 meters, the hot air penetration temperature entering the first oven is 110°C, the hot air penetration temperature in the second oven is 120°C, the running speed in the oven is 15 meters / minute, and the three-layer structure of the absorbent core layer 2 is obtained after exiting the oven.

[0065] The polylactic acid fiber spunlace nonwoven fabric used in the upper layer 21 and the lower layer 23 of the above-mentioned absorbent core layer 2 is a single-component polylactic acid fiber with a fiber specification of 1.5D*38mm and a fiber melting point of 160 degrees. In order to make the core absorb water faster and prevent the liquid from seeping out from the lower layer, the single-component polylactic acid fiber used in the surface layer is a hydrophilic type with a fiber surface oil content of 0.07%, and the single-component polylactic acid fiber used in the lower layer is a water-repellent type with a fiber surface oil content of 0.05%.

[0066] The polylactic acid bicomponent fiber blended with super absorbent resin is a hydrophilic high-curl eccentric fiber, such as Figure 4 As shown in Figure 5, the fiber specification is 1.5D*10mm, the core layer is a high melting point component with a melting point of 160 degrees, and the skin layer is a low melting point component with a melting point of 118 degrees. The mass ratio of the skin layer to the core layer is 4:6. The polylactic acid fiber spunlace non-woven fabric used in the upper and lower layers has a gram weight of 25g / m 2 The core weight is 150 g / m2.

[0067] The super absorbent resin used in the absorbent core layer is a biodegradable absorbent resin of Formosa Plastics Corporation, model BC706, with a biodegradability rate of 66% (180 days). The absorbent core layer is produced by Suzhou Jinquan New Materials Co., Ltd., and the core-type polylactic acid bicomponent fiber, eccentric core-type polylactic acid bicomponent fiber, polylactic acid fiber spunlace nonwoven fabric, and polylactic acid fiber hot air nonwoven fabric are produced by Suzhou Jinquan New Materials Co., Ltd.

[0068] The degradable anti-seepage membrane with polylactic acid as the main component is produced by Fujian Green Grid Biodegradable Co., Ltd., and its electron microscope image is as follows Figure 2 As shown, it can be seen that the membrane structure in the picture is uniform and dense, and the membrane feels relatively soft due to the addition of PHA as a modifier.

[0069] The production of degradable sanitary napkins is a biodegradable sanitary napkin with polylactic acid as the main component, including a polylactic acid fiber hot air non-woven fabric surface layer, an absorbent core layer material with polylactic acid as the main component, and a polylactic acid film modified by PHA. The three materials are processed into biodegradable sanitary napkins through sanitary napkin production equipment.

[0070] Embodiment 2

[0071] The present embodiment involves a biodegradable sanitary napkin with polylactic acid as the main component, including a degradable core, wherein the degradable core includes a surface layer 1, an absorbent core layer 2 and a bottom layer 3; the surface layer 1 is a polylactic acid fiber non-woven fabric; the polylactic acid fiber non-woven fabric is a polylactic acid fiber spunlace non-woven fabric, a polylactic acid fiber hot air non-woven fabric or a polylactic acid spunbond non-woven fabric; the absorbent core layer 2 includes an upper layer 21, a middle layer 22 and a lower layer 23; the upper layer 21 and the lower layer 23 are polylactic acid fiber non-woven fabrics, and the middle layer 22 is a mixture of polylactic acid two-component fibers and super absorbent resin; the bottom layer 3 is a degradable anti-seepage membrane, and the degradable anti-seepage membrane is a PHA-modified polylactic acid membrane.

[0072] In this embodiment, the surface layer 1 is selected as a polylactic acid fiber hot air nonwoven fabric. When producing the polylactic acid hot air nonwoven fabric, two sets of independent opening, mixing, combing and web forming systems of hot air nonwoven fabric production equipment are used, one of which is used to process the upper polylactic acid fiber web, and the second is used to process the lower polylactic acid fiber web. The specific process is as follows:

[0073] The polylactic acid two-component fiber with a specification of 4D*51mm is fed into the second set of opening, mixing, carding and web forming system, fed through the bag opener, and after opening, mixing, carding and random roller randomization, it is stripped by the upper and lower double doffers to form the lower layer of random fiber web. The fiber web weight is 15.5g / m 2 , which is the lower layer of polylactic acid fiber mesh.

[0074] The polylactic acid bicomponent fiber with the specification of 1.5D*38mm is fed into the first system, fed through the bag opener, and after being loosened, mixed, and combed, it is peeled by the upper and lower double doffers and falls on the random fiber web formed by the second system to form an upper fiber web. This system does not contain random rollers and condensation rollers. Instead, the polylactic acid bicomponent fiber is directly peeled by the doffer after passing through the combing machine to form a layer of straight-laid web. In the straight-laid web, the angle with the running direction of the equipment (production direction) is used as a reference. The number of polylactic acid bicomponent fibers arranged in a direction of <30-35° accounts for 75-80% of all fibers in the fiber web. The gram weight of the straight-laid fiber web is 12.5g / m 2 , which is the upper polylactic acid fiber mesh.

[0075] The upper and lower layers of the polylactic acid fiber net formed above are sent into a flat net hot air penetration oven for heat reinforcement. The mesh number of the oven net curtain is 10 meshes, the opening rate is 68%, and the oven is a three-stage oven. The first stage is 115°C, the second stage is 125°C, and the third stage is 115°C. The circulating air volume during heat reinforcement is 8800m3 / h. After passing through an 8-meter cooling channel out of the oven, it is wound into a polylactic acid fiber hot air non-woven fabric surface layer with a thickness of 0.6mm and a gram weight of 28g / m 2 .

[0076] The polylactic acid fiber hot air nonwoven fabric prepared as above, the polylactic acid two-component fiber core layer used in the upper and lower layers of the polylactic acid fiber web is 100% polylactic acid component, and its skin layer includes two situations: 100% polylactic acid component and modified polylactic acid component. In order to be able to be batch processed on conventional hot air nonwoven fabric production equipment, the skin layer preferably uses a modified polylactic acid component, and the modified components include biodegradable materials such as PHA, PBT, PBS, PBAT, PCL, etc. The preferred modified component in the present invention is PHA+PBS, and the ratio of PLA:PHA+PBS=6:4.

[0077] The absorbent core layer 2 is composed of three layers, the upper layer 21 and the lower layer 23 are both polylactic acid fiber spunlace non-woven fabrics, and the middle layer is a mixture of polylactic acid bicomponent fibers and super absorbent resin, and the production method thereof is as follows:

[0078] First, the lower layer 21 of polylactic acid spunlace nonwoven fabric is unrolled, and a layer of polylactic acid bicomponent fiber and super absorbent resin is sprayed on it, with a spraying amount of 70 g / m2, wherein the ratio of polylactic acid bicomponent fiber: super absorbent resin is: 1:9; then a layer of polylactic acid bicomponent fiber and super absorbent resin mixture is applied on it again, with a spraying amount of 50 g / m2, wherein the ratio of polylactic acid bicomponent fiber: super absorbent resin is: 5:5; finally, the upper layer of polylactic acid fiber spunlace nonwoven fabric is unrolled as the surface layer of the core. Subsequently, the above three-layer composite body enters the oven together for thermal reinforcement treatment, using a two-stage flat mesh oven, each oven length of 2 meters, the hot air penetration temperature entering the first oven is 115°C, the hot air penetration temperature in the second oven is 130°C, the running speed in the oven is 20 meters / minute, and the three-layer structure of the absorbent core layer 2 is obtained after exiting the oven.

[0079] The upper layer 21 and the lower layer 23 of the polylactic acid fiber spunlace non-woven fabric in the above-mentioned absorbent core layer 2 are single-component polylactic acid fibers with a fiber specification of 2.0D*38mm and a fiber melting point of 175 degrees. In order to make the core absorb water faster and the liquid not easily seep out from the lower layer, the single-component polylactic acid fiber used in the surface layer is hydrophilic with a fiber surface oil content of 0.08%; the single-component polylactic acid fiber used in the lower layer is water-repellent with a fiber surface oil content of 0.07%.

[0080] The polylactic acid two-component fiber blended with super absorbent resin is a hydrophilic high-curl eccentric core fiber with a fiber specification of 2D*10mm. The core layer is a high-melting point component with a melting point of 175 degrees, and the skin layer is a low-melting point component with a melting point of 135 degrees. The mass ratio of the skin layer to the core layer is 5:5.

[0081] The super absorbent resin used in the absorption core layer is a biodegradable absorbent resin of Formosa Plastics Corporation, model BC706, and its biodegradation rate is 66% (180 days). The weight of the upper and lower layers of polylactic acid fiber spunlace non-woven fabric is 30g / m2. The weight of the core body is 180g / m2. The absorption core layer is produced by Suzhou Jinquan New Materials Co., Ltd., and the core-type polylactic acid bicomponent fiber, eccentric core polylactic acid bicomponent fiber, polylactic acid fiber spunlace non-woven fabric, and polylactic acid fiber hot air non-woven fabric are produced by Suzhou Jinquan New Materials Co., Ltd. The degradable anti-seepage membrane with polylactic acid as the main component is produced by Fujian Green Grid Biodegradation Co., Ltd.

[0082] The production of degradable sanitary napkins is a biodegradable sanitary napkin with polylactic acid as the main component, including a polylactic acid fiber hot air non-woven fabric surface layer, an absorbent core layer material with polylactic acid as the main component, and a polylactic acid film modified by PHA. The three materials are processed into biodegradable sanitary napkins through sanitary napkin production equipment.

[0083] Embodiment 3

[0084] The present embodiment involves a biodegradable sanitary napkin with polylactic acid as the main component, including a degradable core, wherein the degradable core includes a surface layer 1, an absorbent core layer 2 and a bottom layer 3; the surface layer 1 is a polylactic acid fiber non-woven fabric; the polylactic acid fiber non-woven fabric is a polylactic acid fiber spunlace non-woven fabric, a polylactic acid fiber hot air non-woven fabric or a polylactic acid spunbond non-woven fabric; the absorbent core layer 2 includes an upper layer 21, a middle layer 22 and a lower layer 23; the upper layer 21 and the lower layer 23 are polylactic acid fiber non-woven fabrics, and the middle layer 22 is a mixture of polylactic acid two-component fibers and super absorbent resin; the bottom layer 3 is a degradable anti-seepage membrane, and the degradable anti-seepage membrane is a PHA-modified polylactic acid membrane.

[0085] In this embodiment, the surface layer 1 is selected as a polylactic acid fiber hot air nonwoven fabric. When producing the polylactic acid hot air nonwoven fabric, two sets of independent opening, mixing, combing and web forming systems of hot air nonwoven fabric production equipment are used, one of which is used to process the upper polylactic acid fiber web, and the second is used to process the lower polylactic acid fiber web. The specific process is as follows:

[0086] The polylactic acid two-component fiber with a specification of 6.0D*51mm is fed into the second set of opening, mixing, carding and web forming system, fed through the bag opener, and after opening, mixing, carding and random roller randomization, it is stripped by the upper and lower double doffers to form the lower layer of random fiber web. The fiber web weight is 20.5g / m 2, which is the lower layer of polylactic acid fiber mesh.

[0087] The polylactic acid bicomponent fibers with specifications of 1.0 1.5 2.0D*38mm are fed into the first system, fed through the bag opener, and after being loosened, mixed, and combed, they are peeled by the upper and lower double doffers and fall on the random fiber web formed by the second system to form an upper fiber web. This system does not contain random rollers and condensation rollers. Instead, the polylactic acid bicomponent fibers are directly peeled by the doffers after passing through the combing machine to form a layer of straight-laid web. In the straight-laid web, the angle with the running direction of the equipment (production direction) is used as a reference. The number of polylactic acid bicomponent fibers arranged in a direction of <38-45° accounts for 78-88% of all fibers in the fiber web, and the gram weight of the straight-laid fiber web is 15g / m 2 , which is the upper polylactic acid fiber mesh.

[0088] The upper and lower layers of the polylactic acid fiber net formed above are sent into a flat net hot air penetration oven for thermal reinforcement. The mesh number of the oven net curtain is 10 meshes, the opening rate is 68%, the oven is a three-stage oven, the first stage is 120°C, the second stage is 130°C, and the third stage is 120°C. The circulating air volume during thermal reinforcement is 9000m3 / h. After passing through an 8-meter cooling channel out of the oven, it is wound into a polylactic acid fiber hot air non-woven fabric surface layer with a thickness of 1mm and a gram weight of 35.5g / m 2 .

[0089] The polylactic acid fiber hot air nonwoven fabric prepared as above, the polylactic acid two-component fiber core layer used in the upper and lower layers of the polylactic acid fiber net is 100% polylactic acid component, and its skin layer includes two situations: 100% polylactic acid component and modified polylactic acid component. In order to be able to be batch processed on conventional hot air nonwoven fabric production equipment, the skin layer preferably uses a modified polylactic acid component, and the modified components include biodegradable materials such as PHA, PBT, PBS, PBAT, PCL, etc. The preferred modified component in the present invention is PHA+PBS, and the ratio of PLA:PHA+PBS=5:5.

[0090] The absorbent core layer 2 is composed of three layers, the upper layer 21 and the lower layer 23 are both polylactic acid fiber spunlace non-woven fabrics, and the middle layer is a mixture of polylactic acid bicomponent fibers and super absorbent resin, and the production method thereof is as follows:

[0091] First, the lower layer 21 of polylactic acid spunlace nonwoven fabric is unrolled, and a layer of polylactic acid bicomponent fiber and super absorbent resin is sprayed on it, with a spraying amount of 80 g / m2, wherein the ratio of polylactic acid bicomponent fiber: super absorbent resin is: 2:8; then a layer of polylactic acid bicomponent fiber and super absorbent resin mixture is applied on it again, with a spraying amount of 50 g / m2, wherein the ratio of polylactic acid bicomponent fiber: super absorbent resin is: 5:5; finally, the upper layer of polylactic acid fiber spunlace nonwoven fabric is unrolled as the surface layer of the core. Subsequently, the above three-layer composite body enters the oven together for thermal reinforcement treatment, using a two-stage flat mesh oven, each oven length of 2 meters, the hot air penetration temperature entering the first oven is 120°C, the hot air penetration temperature in the second oven is 140°C, the running speed in the oven is 25 meters / minute, and the three-layer structure of the absorbent core layer 2 is obtained after exiting the oven.

[0092] The upper and lower layers of the polylactic acid fiber spunlace non-woven fabric in the above-mentioned absorbent core layer 2 are single-component polylactic acid fibers with a fiber specification of 2.0D*38mm and a fiber melting point of 175 degrees. In order to make the core absorb water faster and the liquid not easily seep out from the lower layer, the single-component polylactic acid fiber used in the surface layer is hydrophilic, and the fiber surface oil content is 0.09%. The single-component polylactic acid fiber used in the lower layer is water-repellent, and the fiber surface oil content is 0.08%.

[0093] The polylactic acid two-component fiber blended with the super absorbent resin is a hydrophilic high-curl eccentric fiber with a fiber specification of 3.0D*10mm. The core layer is a high-melting component with a melting point of 175 degrees, and the skin layer is a low-melting component with a melting point of 135 degrees. The mass ratio of the skin layer to the core layer is 6:4. The super absorbent resin used in the absorbent core layer is a biodegradable absorbent resin of Formosa Plastics Corporation, model BC706, and its biodegradation rate is 66% (180 days). The weight of the upper and lower polylactic acid fiber spunlace non-woven fabrics is 50g / m2. The weight of the core body is 230g / m2. The absorbent core layer is produced by Suzhou Jinquan New Materials Co., Ltd., and the core-type polylactic acid two-component fiber, eccentric core polylactic acid two-component fiber, polylactic acid fiber spunlace non-woven fabric, and polylactic acid fiber hot air non-woven fabric are produced by Suzhou Jinquan New Materials Co., Ltd. The base film with polylactic acid as the main component is produced by Fujian Green Grid Biodegradable Co., Ltd.

[0094] The production of degradable sanitary napkins is a biodegradable sanitary napkin with polylactic acid as the main component, including a polylactic acid fiber hot air non-woven fabric surface layer, an absorbent core layer material with polylactic acid as the main component, and a polylactic acid film modified by PHA. The three materials are processed into biodegradable sanitary napkins through sanitary napkin production equipment.

[0095] The main properties of the polylactic acid fiber hot air non-woven fabric surface layer and the prepared degradable sanitary napkin in the above embodiment were tested:

[0096] The test items include the degradation performance and water absorption rate of degradable sanitary napkins; the antibacterial property, air permeability, moisture conductivity and pH value of the surface of polylactic acid fiber hot air non-woven fabrics. The specific test methods are as follows:

[0097] Antibacterial property: GB15979-2002 (hygienic standard for disposable sanitary products).

[0098] Air permeability: Tested according to GB / T5453-1997 standard. Adjust the test pressure difference to 60Pa and select a nozzle diameter of 5mm.

[0099] Moisture conductivity: Tested according to ZB W 04019-1990 standard. Test fabric sample size 25mm*300mm, measure water absorption height in 60s.

[0100] pH value: Tested according to the method specified in Appendix C of GB / T 8939-2008.

[0101] Water absorption rate: tested according to the method specified in GB / T 8939-2008 standard.

[0102] Degradability: Evaluated according to the method and conditions of GB / T19277-2003 (IDT ISO 14855:1999).

[0103] The detection structure is shown in Table 1.

[0104] Table 1: Biodegradable sanitary napkin performance test

[0105]

[0106] The properties of the degradable impermeable membrane are shown in Table 2.

[0107] Table 2 Performance indicators of degradable anti-seepage membrane

[0108]

[0109] The degradation performance test of the biodegradable sanitary napkin prepared by the present invention is described by taking the biodegradable sanitary napkin prepared in Example 1 as an example. Figure 9-13 After 13 weeks of degradation, the fragments had turned into pieces smaller than 10 mm, indicating a successful degradation experiment.

[0110] The results of the sanitary napkin degradation experiment of the present invention are as follows:

[0111]

[0112] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A biodegradable sanitary napkin with polylactic acid as the main component, comprising a degradable core, characterized in that: The degradable core comprises a surface layer, an absorbent core layer and a bottom layer; The surface layer is a polylactic acid fiber nonwoven fabric; the polylactic acid fiber nonwoven fabric is a polylactic acid fiber spunlace nonwoven fabric, a polylactic acid fiber hot air nonwoven fabric or a polylactic acid spunbond nonwoven fabric; The absorbent core layer comprises an upper layer, a middle layer and a lower layer; the upper layer and the lower layer are polylactic acid fiber non-woven fabrics, and the middle layer is a mixture of polylactic acid bicomponent fibers and highly absorbent resin; The bottom layer is a degradable anti-seepage membrane, and the degradable anti-seepage membrane is a PHA-modified polylactic acid membrane.

2. The biodegradable sanitary napkin with polylactic acid as the main component according to claim 1, characterized in that: The surface layer is a polylactic acid hot air nonwoven fabric, and the fiber used is a bicomponent composite polylactic acid fiber; the polylactic acid hot air nonwoven fabric comprises an upper polylactic acid fiber net and a lower polylactic acid fiber net; the specification of the bicomponent composite polylactic acid fiber used in the upper polylactic acid fiber net is 1.0-2.0D*38mm, and the specification of the bicomponent composite polylactic acid fiber used in the lower polylactic acid fiber net is 3.0-6.0D*51mm; The two-component composite polylactic acid fiber comprises a cortex and a core layer with the same core; the cortex is a low-melting-point polylactic acid component or a modified polylactic acid component; the melting point of the polylactic acid component in the core layer is 160-175°C, and the melting point of the polylactic acid component in the cortex is 118-135°C.

3. The biodegradable sanitary napkin with polylactic acid as the main component according to claim 2, characterized in that: The modified polylactic acid component includes a polylactic acid component and a modified component, and the modified component includes a PHA, PBT, PBS, PBAT or PCL biodegradable material.

4. The biodegradable sanitary napkin with polylactic acid as the main component according to claim 3, characterized in that: The modified components are PHA and PBS; and the weight ratio of the polylactic acid component to the modified component is 7-5:5-3.

5. The biodegradable sanitary napkin with polylactic acid as the main component according to claim 2, characterized in that: The content of the surface oil in the two-component composite polylactic acid fiber used in the upper polylactic acid fiber net is 0.02-0.1%; the surface oil contains Lurol PP-12147 hydrophilic oil.

6. The biodegradable sanitary napkin with polylactic acid as the main component according to claim 2, characterized in that: The production equipment of the hot air nonwoven fabric of polylactic acid comprises two sets of independent opening, mixing and carding systems, the first set is used to prepare the upper polylactic acid fiber web, and the second set is used to prepare the lower polylactic acid fiber web; The production of the hot air nonwoven fabric of polylactic acid comprises the following steps: 1) The polylactic acid two-component fiber with a specification of 3.0-6.0D*51mm is fed into the second set of opening, mixing, carding and web forming system, fed through the bag opener, and after opening, mixing, carding and random roller randomization, the upper and lower double doffers are used to peel the web to form a lower layer of random fiber web, and the fiber web weight is 10.5-20.5g / m2; 2) The polylactic acid bicomponent fibers with specifications of 1.0-2.0D*38mm are fed into the first set of opening, mixing, carding and web forming systems, fed through the bag opener, and after opening, mixing and carding, they are peeled off by upper and lower double doffers and fall on the random fiber web formed by the second system to form an upper fiber web. This system does not contain random rollers and condensation rollers. Instead, the polylactic acid bicomponent fibers are directly stripped by doffers after passing through the carding machine to form a layer of straight-laid web. In the straight-laid web, the angle with the equipment running direction (production direction) is used as a reference. The number of polylactic acid bicomponent fibers arranged in a direction of <20-45° accounts for 70-88% of all fibers in the fiber web, and the gram weight of the straight-laid fiber web is 8.9-15g / m 2 ; 3) The upper and lower fiber webs formed above are sent into a flat net hot air penetration oven for heat consolidation. The mesh number of the oven net curtain is 10 meshes, the opening rate is 68%, and the oven is a three-stage oven. The first stage is 100-120°C, the second stage is 120-130°C, and the third stage is 110-120°C. The circulating air volume during heat consolidation is 8200-9000m 3 / h, after leaving the oven and passing through a cooling channel of 5-8 meters, it is wound into a polylactic acid fiber hot air non-woven fabric surface layer with a thickness of 0.2-1mm.

7. The biodegradable sanitary napkin with polylactic acid as the main component according to claim 1, characterized in that: The upper layer and the lower layer are polylactic acid spunlace nonwoven fabrics.

8. The biodegradable sanitary napkin with polylactic acid as the main component according to claim 7, characterized in that: The preparation process of the absorbent core layer is as follows: First, unwind the lower layer, and spray a layer of a mixture of polylactic acid bicomponent fiber and super absorbent resin on the surface of the lower layer, with a spraying amount of 60-80 g / m2, wherein the ratio of polylactic acid bicomponent fiber to super absorbent resin is 0-2:8-10; Then, a layer of a mixture of polylactic acid bicomponent fiber and super absorbent resin is sprayed thereon again, with a spraying amount of 40-50 g / m2, wherein the ratio of polylactic acid bicomponent fiber to super absorbent resin is 5:5; Finally, the upper layer is unrolled and placed above the middle layer; Then the three-layer composite body is put into an oven together for heat consolidation treatment.

9. The biodegradable sanitary napkin with polylactic acid as the main component according to claim 8, characterized in that: The thermal reinforcement treatment uses a two-stage flat-mesh oven, each section of the oven is 2 meters long, the hot air penetration temperature entering the first section of the oven is 110-120°C, and the hot air penetration temperature in the second section of the oven is 120-140°C. The running speed in the oven is 15-25 meters / minute, and after leaving the oven, a three-layer core layer is obtained with a gram weight of 150-230 grams / square meter.

10. The biodegradable sanitary napkin with polylactic acid as the main component according to claim 8, characterized in that: The polylactic acid fiber spunlace nonwoven fabric used in the upper and lower layers is a single-component polylactic acid fiber with a fiber specification of 1.5-2.0D*38mm and a fiber melting point of 160-175°C. In order to make the core absorb water faster and prevent the liquid from seeping out from the lower layer, the single-component polylactic acid fiber used in the upper layer is a hydrophilic type with a fiber surface oil content of 0.07-0.09%, and the single-component polylactic acid fiber used in the lower layer is a water-repellent type with a fiber surface oil content of 0.05-0.08%; the polylactic acid fiber spunlace nonwoven fabric has a gram weight of 25-50g / m 2 . The polylactic acid two-component fiber blended with super absorbent resin is a hydrophilic high-curl eccentric core fiber with a fiber specification of 1.5-3.0D*10mm. The core layer is a high-melting point component with a melting point of 160-175 degrees, and the skin layer is a low-melting point component with a melting point of 118-135 degrees. The mass ratio of the skin layer to the core layer is 4-6:4-6.

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