A biodegradable diaper

Abstract

The application discloses a biodegradable paper diaper, which comprises a paper diaper body, a leakage-proof side, a magic tape and an elastic waistband; the paper diaper body comprises a surface layer, an absorption core layer and a permeation-preventing bottom film; the surface layer is a porous polylactic acid fiber hot air non-woven fabric; the absorption core layer comprises an upper layer, a middle layer and a lower layer; the upper layer is dust-free paper; the middle layer is a polylactic acid fiber flow guide layer containing biodegradable super absorbent resin; and the lower layer is polylactic acid fiber spunlace non-woven fabric; the permeation-preventing bottom film is a PHA modified polylactic acid film. The weak acidity and natural antibacterial property have been detected and certified by an authoritative agency, and the biodegradable paper diaper is especially suitable for processing disposable sanitary products such as sanitary napkins and pads. The polylactic acid fiber hot air non-woven fabric has the characteristics of fast infiltration speed, ability of guiding thin stool, dryness, air permeability and softness. Through preparation and selection of various polylactic acid fiber non-woven fabrics and in cooperation with the compostable super absorbent resin, the compostable standard is fully met.

Description

TECHNICAL FIELD

[0001] The application relates to a biodegradable paper diaper. BACKGROUND

[0002] The paper diapers on the market mainly include three categories of products, namely baby paper diapers, adult paper diapers and pet diapers, among which baby paper diapers account for the largest proportion. According to the latest report "Global Baby Paper Diaper Market Report 2023-2029" of QYResearch research team, it is predicted that the global baby paper diaper market size will reach 48.85 billion US dollars in 2029, and the compound annual growth rate CAGR will be 2.5% in the next few years. The main raw materials for making paper diapers are polyethylene, polypropylene, water-absorbing resin, hot melt adhesive and other non-degradable plastics. According to the popular ultra-thin paper diaper (i.e. the composition materials are: surface hot air non-woven fabric, dust-free paper, fluffy hot air non-woven fabric, macromolecule, coating layer, hot melt adhesive and bottom film), the non-degradation rate of the materials used is more than 90%. Therefore, from the perspective of sustainable development of the ecological environment, it is very important to research and develop paper diapers that can be composted and reach the level of large-scale production, which is beneficial to the sustainable development of the environment and the future generations.

[0003] However, from the existing data, the research and development of existing degradable paper diapers deviates from reality, and only some experiments are done in the laboratory. The preparation method and material cost are very high, and it is difficult to scale up with existing equipment. Therefore, it is very important to develop and produce biodegradable paper diapers with cost advantages, which can be mass-produced on existing equipment and have certain functionality. SUMMARY

[0004] The purpose of the present application is to provide a biodegradable paper diaper with antibacterial and biodegradable properties.

[0005] To solve the above technical problems, the purpose of the present application is achieved as follows:

[0006] The biodegradable paper diaper of the present application comprises a paper diaper body, a leakage-proof side, a magic tape and an elastic waistband. The paper diaper body comprises a surface layer, an absorption core layer and a permeation-preventing bottom film.

[0007] The surface layer is a porous polylactic acid fiber hot air non-woven fabric. The absorption core layer comprises an upper layer, a middle layer and a lower layer. The upper layer is dust-free paper. The middle layer is a polylactic acid fiber flow guide layer containing biodegradable superabsorbent resin. The lower layer is a polylactic acid fiber spunlace non-woven fabric.

[0008] The permeation-preventing bottom film is a PHA modified polylactic acid film.

[0009] On the basis of the above scheme and as a preferred scheme of the above scheme: the PLA:PHA in the PHA modified polylactic acid film is 3-7:7-3.

[0010] On the basis of the above scheme and as a preferred scheme of the above scheme: the polylactic acid fiber hot air non-woven fabric is composed of low-melting-point polylactic acid fiber and high-low-melting-point polylactic acid fiber in a weight ratio of 25-45:55-75, wherein the specification of the low-melting-point polylactic acid fiber is 1.5-3.0D*38mm, and the specification of the high-low-melting-point polylactic acid fiber is 1.0-2.0D*38mm; the core layer of the high-low-melting-point polylactic acid fiber is a high-melting-point polylactic acid component, and the skin layer is a low-melting-point polylactic acid component or a modified polylactic acid component; the low-melting-point polylactic acid fiber is a modified polylactic acid component.

[0011] On the basis of the above scheme and as a preferred scheme of the above scheme: the modified component used in the modified polylactic acid component at least includes one of PHA, PBT, PBS, PBAT or PCL.

[0012] On the basis of the above scheme and as a preferred scheme of the above scheme: the preparation process of the polylactic acid fiber hot air non-woven fabric is as follows:

[0013] The speed of the beater of the opener is controlled to be 250-380r / min during opening, the cross-laying and straight-taking method is used for blending during blending, the speed of the cotton roller is controlled to be between 180-220r / min during cotton blending, the speed of the beater of the opener is controlled to be 550-680r / min during fine opening, the air pressure of the cotton box is controlled to be between 3-4.8MPa during the air flow cotton feeding process, the speed of the mixing roller of the cotton box is controlled to be between 310-430r / min, the speed of the cotton roller is controlled to be between 18.2-25.5r / min, the speed of the cylinder is adjusted to be between 610-750m / min during the carding process, the speed of the work roller is controlled to be between 42.5-58.9m / min, the speed of the stripping roller is controlled to be between 120.3-141.2m / min, the speed of the doffer is controlled to be between 20.5-30.6m / min, and the single-layer web formed after the condensing roller and the stripping roller stripping is 9.8-15.4g / m2. The setting is a four-section flat screen oven, the setting temperature of the four-section oven is controlled to be 100-110 degrees, 125-135 degrees, 120-130 degrees and 110-120 degrees respectively, the running speed of the web in the oven is 70-80mi / min, and the polylactic acid fiber hot air non-woven fabric composed of low-melting-point polylactic acid fiber and high-low-melting-point polylactic acid fiber is obtained after the oven.

[0014] 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:

[0015] Firstly, the lower layer of polylactic acid spunlace non-woven fabric is unwound, and a layer of high-low melting point polylactic acid fiber and high water absorbing resin mixture is sprayed on it, the spraying amount is 30-50 g / m2, wherein the ratio of high-low melting point polylactic acid bi-component fiber: high water absorbing resin is: 0.5-1.5: 98.5-99.5, and the particle size of the high water absorbing resin is 80-90 mesh;

[0016] The polylactic acid fiber high-porosity flow layer material is unwound and laid on the surface of the high-low melting point polylactic acid fiber and high water absorbing resin mixture, and then high water absorbing resin is sprayed on it, the spraying amount is 70-80 g / m2, wherein the particle size of the high water absorbing resin is 60-70 mesh. The sprayed lower layer of polylactic acid spunlace non-woven fabric and the polylactic acid fiber high-porosity flow layer are sent together to the upper and lower reciprocating vibration type conveying long curtain driven by the transmission device. The conveying long curtain generates vibration by driving the eccentric mechanism of the motor to generate excitation force. The vibration intensity can be controlled in the range of 3-6, the vibration frequency that can be generated is 25-30 Hz, and the amplitude is 2-4 mm, so that the sprayed high water absorbing resin is better dispersed in the polylactic acid fiber high-porosity flow layer.

[0017] After the vibration type conveying long curtain, a layer of high-low melting point polylactic acid bi-component fiber and high water absorbing resin mixture is sprayed on the surface of the polylactic acid fiber high-porosity flow layer again, the spraying amount is 15-30 g / m2, wherein the ratio of high-low melting point polylactic acid fiber: high water absorbing resin is: 50: 50, and the particle size of the high water absorbing resin is 30-40 mesh.

[0018] Finally, the dust-free paper is unwound as the upper layer of the absorbent;

[0019] The three layers after superposition are put into an oven for heat setting and reinforcement, a three-section flat net oven is used, the heating temperature in the first section oven is controlled at 110-120°C, the heating temperature in the second section oven is controlled at 120-140°C, and the heating temperature in the third section oven is controlled at 110-120°C. After the oven, the three-layer structure of the absorbent layer is obtained, and the grammage is 180-240 g / m2.

[0020] The polylactic acid fiber spunlace non-woven fabric has a grammage of 30-40 g / m2, and high melting point polylactic acid fiber is used. The fiber is water-repellent, the fiber surface oil content is 0.06-0.08%, and the melting point of the high melting point polylactic acid fiber is 160-175 degrees.

[0021] On the basis of the above scheme and as a preferred scheme of the above scheme: the low melting point polylactic acid fiber and the high-low melting point polylactic acid fiber used in the spinning process add Lurol PP-14160 type hydrophilic oil to the surface oil.

[0022] As a preferred scheme of the above scheme and on the basis of the above scheme: the surface oil agent content of the low-melting polylactic acid fiber is 0.02-0.08%, and the surface oil agent content of the high-low-melting polylactic acid fiber is 0.12-0.15%.

[0023] Compared with the prior art, the biodegradable paper diaper prepared by the application has the following beneficial effects:

[0024] 1) Natural weak acidity and bacteriostasis

[0025] The polylactic acid (PLA) fiber is an environmentally friendly biomass material, which has the characteristics of biodegradability, weak acidity on the fiber surface, natural bacteriostasis and odor removal function. The weak acidity and natural bacteriostasis have been certified by authoritative agencies, and it is particularly suitable for processing disposable sanitary products such as paper diapers, sanitary napkins and panty liners.

[0026] 2) Fast infiltration speed and good dryness

[0027] The surface layer of the paper diaper of the application is composed of low-melting single-component polylactic acid fiber and high-low-melting polylactic acid double-component fiber in the hot air non-woven fabric. Since the crystallinity of the low-melting single-component polylactic acid fiber is low, it is prone to shrinkage during heating, thereby pulling and dragging the surrounding high-low-melting polylactic acid double-component fiber, forming numerous pores in the fiber web. The more the content of the low-melting single-component polylactic acid fiber, the higher the porosity of the fiber web, which greatly improves the pore structure of the fiber web. At this time, the high-low-melting polylactic acid double-component fiber not only serves as the framework of the fiber web, but also plays a role in bonding and fixing the low-melting single-component polylactic acid fiber. Combined with the regulated hot air production process, the polylactic acid fiber hot air non-woven fabric containing multiple pores is successfully prepared. Since the surface moisture regain of the polylactic acid fiber is only about 0.4%, the prepared polylactic acid fiber hot air non-woven fabric has the characteristics of fast infiltration speed, can guide thin feces, dryness, air permeability and softness.

[0028] 3) Fast absorption speed and low back seepage

[0029] The absorption core layer of the application uses the high-loft patent guide layer of polylactic acid fiber as the main absorption material. The high-loft and guide properties of the high-loft patent guide layer provide a good carrier for dispersing and wrapping the superabsorbent resin, and its unique high water conductivity can quickly guide the liquid from the surface layer to the surrounding superabsorbent resin, avoiding the saturation of local superabsorbent resin and the resulting blockage, providing sufficient swelling space for the absorption of liquid, making full use of the absorption capacity of the superabsorbent resin, thereby reducing the amount of superabsorbent resin used and reducing production costs. On the other hand, it also eliminates the use of hot melt adhesive to bond and fix the superabsorbent resin in the core of the traditional paper diaper, further reducing the content of non-degradable components in the paper diaper.

[0030] 4) Processability with conventional equipment

[0031] All non-woven materials used in the paper diaper of the present application, 100% polylactic acid fiber hot air non-woven fabric for the surface layer, non-dust paper containing polylactic acid fiber for the middle absorption layer, high degradation rate and high loft polylactic acid fiber flow layer, polylactic acid fiber spunlace non-woven fabric, and polylactic acid spunbond non-woven fabric can be successfully produced on existing conventional equipment, and there are manufacturers, which fully meet the mass production scale, and the downstream market clients are urgently developed.

[0032] 5) Biodegradability

[0033] Due to the complex structure of the paper diaper, the variety of materials is complex and miscellaneous, and it is very difficult to truly realize biodegradability. Even so, through the calculation of the materials used for the paper diaper, among all the materials (surface layer non-woven fabric, middle absorption core layer, impermeable bottom film, leakage prevention side edge, hot melt adhesive, magic tape and elastic waist) for the paper diaper, the absorption core layer accounts for 55.06%, the surface layer non-woven fabric, the bottom impermeable film, the elastic waist non-woven fabric and the leakage prevention side edge non-woven fabric account for 34.44%, the absorption core layer and various non-woven fabrics in ordinary thin baby paper diapers account for 89.5%, and the remaining hot melt adhesive, front waist tape, elastic waist rubber, leg rubber and three-dimensional protective rubber, magic buckle and left and right tape non-woven fabric account for only 10.5%. Therefore, through the preparation and selection of various polylactic acid fiber non-woven fabrics, and in combination with the compostable superabsorbent resin (ISO14855: 180-day biodegradation rate ≥60%), the compostable standard is fully met.

[0034] Biodegradable superabsorbent resin (the biodegradation rate of BC706 type biodegradable superabsorbent 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 ≥60%, which can meet the degradation standard requirements). BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 is a structural schematic diagram of the paper diaper body;

[0036] Figure 2 is a cross-sectional structure diagram of high and low melting point polylactic acid fiber;

[0037] Figure 3 is a longitudinal structure diagram of high and low melting point polylactic acid fiber;

[0038] Figure 4 is a cross-sectional structure diagram of low melting point polylactic acid fiber;

[0039] Figure 5 is a longitudinal structure diagram of low melting point polylactic acid fiber;

[0040] Figure 6is the surface photo of polylactic acid fiber hot air non-woven fabric;

[0041] Figure 7 is the electron microscope photo of polylactic acid fiber hot air non-woven fabric;

[0042] Figure 8 is the structure diagram of the absorbent core layer;

[0043] Figure 9 is the three-fold state of the biodegradable diaper prepared by the present application;

[0044] Figure 10 is the unfolded state of the biodegradable diaper prepared by the present application;

[0045] Figure 11 is the biodegradable diaper after four weeks of degradation experiment;

[0046] Figure 12 is the biodegradable diaper after six weeks of degradation experiment;

[0047] Figure 13 is the biodegradable diaper after eleven weeks of degradation experiment;

[0048] Figure 14 is the biodegradable diaper after twelve weeks of degradation experiment;

[0049] Figure 15 is the biodegradable diaper after thirteen weeks of degradation experiment;

[0050] Figure 16 is the relationship curve of carbon dioxide release rate (kg / ton / day) and time (week).

[0051] The mark in the figure is explained as follows: 1-surface layer; 2-absorbent core layer; 3-impervious bottom film. DETAILED DESCRIPTION

[0052] The present application is further explained in conjunction with the accompanying drawings and specific embodiments.

[0053] Example 1

[0054] The biodegradable diaper of the present application comprises a diaper body, leakage-proof side edges, magic tapes and elastic waistbands; the diaper body comprises a surface layer 1, an absorbent core layer 2 and an impervious bottom film 3; the surface layer 1 is porous polylactic acid fiber hot air non-woven fabric, the absorbent core layer 2 comprises an upper layer, a middle layer and a lower layer; the upper layer is dust-free paper, the middle layer is a polylactic acid fiber flow guide layer containing biodegradable superabsorbent resin, and the lower layer is polylactic acid fiber spunlace non-woven fabric; the impervious bottom film 3 is a PHA modified polylactic acid film.

[0055] The preparation method of the porous polylactic acid fiber hot air nonwoven fabric used in the surface layer 1 in the embodiment is as follows:

[0056] A common hot air cotton production line, such as the hot air cotton production line produced by Changshu Jiuyi High-tech Nonwoven Equipment Co., Ltd., is adopted, and the process flow is mixing, coarse opening, cotton mixing, fine opening, air flow feeding, carding, web forming and heat setting processes. Since the melting point of the single-component polylactic acid fiber is low, in order to avoid the problems such as the melting of the polylactic acid fiber in the processes of opening, carding and heat setting, the original opening mixing and carding and setting processes of the PE / PP hot air nonwoven fabric production are adjusted, the longitudinal and transverse arrangement directions of the fiber in the web are reasonably controlled, including the control of various speed ratios of the cylinder, the working roller and the stripping roller, the cylinder and the doffer, the condensing roller and the doffer, the selection of the drafting ratio, and the selection of the web forming and setting weight. A special process scheme of large pitch, low drafting, low speed, light weight, weak carding, low tension and multi-stage setting is adopted to further reduce the excessive friction and heat-sensitive brittleness of the fiber. The produced low-melting polylactic acid fiber and high-low-melting polylactic acid fiber hot air nonwoven fabric has a fiber web with a three-dimensional structure of correct fiber arrangement direction, multiple pores and irregular pore distribution, which meets the requirements of web uniformity, thickness, weight and the ratio of longitudinal and transverse strength. The low-melting polylactic acid fiber and the high-low-melting polylactic acid fiber are in a proportion of 25:75.

[0057] The main process parameters are as follows: the beater speed of the opening machine is controlled at 380 r / min during opening, the cotton is mixed by the way of horizontal laying and direct taking during the cotton mixing process, so as to achieve the purpose of fully mixing the low-melting polylactic acid fiber and the high-low-melting polylactic acid fiber, the speed of the even cotton roller is controlled between 220 r / min during the cotton output, the speed of the opening machine is controlled at 680 r / min during fine opening, the air pressure of the air pressure cotton box is controlled between 4.8 MPa during the air flow feeding process, the speed of the air pressure cotton box mixing roller is controlled between 430 r / min, the speed of the cotton output roller is 25.5 r / min, the linear speed of the cylinder is adjusted to 750 m / min during the carding process, the linear speed of the working roller is controlled at 58.9 m / min, the linear speed of the stripping roller is 141.2 m / min, and the doffer speed is controlled at 30.6 m / min. The single-layer web formed after the condensing roller and the stripping roller has a weight of 9.8 g / m 2 . The setting is a four-stage flat web oven, the setting temperatures of the four-stage ovens are controlled at 110℃, 135℃, 130℃ and 120℃ respectively, the running speed of the web in the oven is 80 mi / min, and the low-melting polylactic acid fiber and the high-low-melting polylactic acid fiber hot air nonwoven fabric with a weight of 19.6 g / m2 are obtained after the output of the oven.

[0058] Among the above, the low-melting-point single-component polylactic acid fiber and the high-low-melting-point polylactic acid double-component fiber are specially developed and produced by Suzhou Jinquan New Material Co., Ltd. The high-low-melting-point polylactic acid fiber skin layer is a modified polylactic acid component, as shown in Figure 2 and Figure 4 The modified component includes PHA, PBT, PBS, PBAT, PCL and other biodegradable materials, and the preferred modified component in the application is PHA+PBS. In addition, the low-melting-point polylactic acid fiber is also a modified fiber, as shown in Figure 4 and Figure 5 The modified component includes PHA, PBT, PBS, PBAT, PCL and other biodegradable materials, and the preferred modified component is PHA, and the modified fiber ratio is PLA:PHA=95:5.

[0059] Among the above, the low-melting-point polylactic acid fiber has a melting point of 118-135℃, the core layer of the high-low-melting-point polylactic acid fiber is a high-melting-point polylactic acid component, wherein the melting point of the core layer is 160-175℃, and the skin layer is a low-melting-point component with a melting point of 118-135℃. The prepared polylactic acid fiber hot air non-woven fabric is as shown in Figure 6 and Figure 7

[0060] The absorbent core layer 2 includes an upper layer, a middle layer and a lower layer, the upper layer is dust-free paper, the middle layer is a polylactic acid fiber flow guide layer, the flow guide layer contains biodegradable superabsorbent resin, and the bottom layer is a polylactic acid fiber spunlace non-woven fabric.

[0061] The surface layer of the dust-free paper has a grammage of 35g / m 2 The dust-free paper is a heat-sealed dust-free paper, which contains wood pulp fiber and high-low-melting-point polylactic acid fiber in a fiber ratio of 75:25, wherein the length of the high-low-melting-point polylactic acid fiber is 3mm and the curling degree is 0. The dust-free paper is produced by Jiaxing Shixin Nonwoven Co., Ltd.

[0062] ​In production, firstly, the lower polylactic acid spunlace non-woven fabric is unwound, a layer of high-low melting point polylactic acid fiber and high water absorption resin mixture is sprayed on it, the spraying amount is 30 g / m2, the ratio of high-low melting point polylactic acid bicomponent fiber: high water absorption resin is: 0.5:99.5, the particle size of the high water absorption resin is 80 meshes; the polylactic acid fiber high-porosity flow layer material is unwound and laid on the surface of the high-low melting point polylactic acid fiber and high water absorption resin mixture, then high water absorption resin is sprayed on it, the spraying amount is 70 g / m2, the particle size of the high water absorption resin is 60 meshes, the lower polylactic acid spunlace non-woven fabric and the polylactic acid fiber high-porosity flow layer after spraying are sent to the upper and lower reciprocating vibration type conveying long curtain driven by the transmission device, the conveying long curtain is vibrated by the eccentric mechanism driven by the motor to generate excitation force, the vibration intensity can be controlled in the range of 3, the vibration frequency that can be generated is 25 Hz, the amplitude is 2 mm, so that the sprayed high water absorption resin is better dispersed in the polylactic acid fiber high-porosity flow layer; after the vibration type conveying long curtain, a layer of high-low melting point polylactic acid bicomponent fiber and high water absorption resin mixture is sprayed on the surface of the polylactic acid fiber high-porosity flow layer again, the spraying amount is 15 g / m2, the ratio of high-low melting point polylactic acid bicomponent fiber: high water absorption resin is: 50:50, the particle size of the high water absorption resin is 30 meshes, and finally the upper dust-free paper is unwound as the surface layer of the absorbent.

[0063] The above three-layer composite enters the oven for heat setting and reinforcement, a three-section flat net oven is adopted, the heating temperature in the first section oven is controlled to be 110°C, the heating temperature in the second section oven is controlled to be 120°C, and the heating temperature in the third section oven is controlled to be 110°C, and a three-layer structure of the absorbing layer is obtained after the oven, and the grammage is 180 g / m2.

[0064] The polylactic acid fiber spunlace non-woven fabric in the above has a grammage of 30 g / m2. 2 The high melting point polylactic acid fiber is used, the fiber is water-repellent type, the surface oil content of the fiber is 0.06%, and the melting point of the high melting point single-component polylactic acid fiber is 160-175 degrees.

[0065] For the low melting point polylactic acid fiber and the high-low melting point polylactic acid fiber, Lurol PP-14160 type hydrophilic oil is specially added in the spinning oil in the spinning process, which has the functions of single-point multiple hydrophilic and fast water penetration speed, the surface oil content of the low melting point single-component polylactic acid fiber is controlled to be 0.02%, and the surface oil content of the high-low melting point polylactic acid bicomponent fiber is 0.12%. The different oil contents mainly make the single-component polylactic acid fiber better produce the melting and bonding effect in the subsequent processing process.

[0066] In the above, the polylactic acid fiber high-loft flow layer is a flow layer with an invention patent of Suzhou Jinquan New Material Co., Ltd., specifically a high-degradation-rate flow layer material and a preparation method thereof, and the patent authorization number is ZL201710096961.0. The high water-absorbing resin used in the absorption core layer is a biodegradable water-absorbing resin of Taiwan Plastic Co., Ltd., model BC706, with a biodegradation rate of 66% (180 days). The prepared absorption core layer is as shown in Figure 8 .

[0067] The impermeable bottom film 3 is a composite film of polylactic acid fiber spunlace non-woven fabric and a degradable polylactic acid modified film with polylactic acid component as the main component, and the modified component is PHA, PBHA, PBS, etc., and the preferred one is PHA. The bottom film with polylactic acid component as the main component is produced by Fujian Lvge Biodegradable Co., Ltd. The grammage of the polylactic acid fiber spunlace non-woven fabric composite film is 55 g / m2.

[0068] Since the paper diaper is a composite of multiple materials, there are also non-woven fabrics for leak-proof cuffs and elastic waistbands. The leak-proof cuffs can use polylactic acid fiber spunlace non-woven fabric composite film with a grammage of 40 g / m2, and the non-woven fabric for elastic waistbands uses polylactic acid spunbond non-woven fabric (produced by Shanghai Jingfa Industrial Co., Ltd.) with a grammage of 35 g / m2. Other components include hot melt adhesive, waist patches, magic buckles, and rubber bands, which account for only about 10.5%, and can be ignored.

[0069] The biodegradable paper diaper includes 100% polylactic acid fiber hot air non-woven fabric, an absorption core layer material with polylactic acid as the main component, and polylactic acid fiber spunlace non-woven fabric composite film, polylactic acid leak-proof cuffs, and polylactic acid spunbond non-woven fabric elastic waistbands. The above materials are processed into biodegradable paper diapers by conventional paper diaper production equipment. The prepared paper diaper is as shown in Figure 9 and Figure 10 The three-fold length is 145.4 mm and the width is 100.5 mm. Figure 9

[0070] Example Two

[0071] The biodegradable paper diaper of the present embodiment includes a paper diaper body, leak-proof side edges, magic patches, and elastic waistbands. The paper diaper body includes a surface layer 1, an absorption core layer 2, and an impermeable bottom film 3. The surface layer 1 is a porous polylactic acid fiber hot air non-woven fabric. The absorption core layer 2 includes an upper layer, a middle layer, and a lower layer. The upper layer is dust-free paper, the middle layer is a polylactic acid fiber flow layer containing biodegradable superabsorbent resin, and the lower layer is polylactic acid fiber spunlace non-woven fabric. The impermeable bottom film 3 is a PHA modified polylactic acid film.

[0072] ​The preparation method of the porous polylactic acid fiber hot air nonwoven fabric used in the surface layer 1 in the embodiment is as follows:

[0073] The process flow is mixing, coarse opening, cotton mixing, fine opening, air flow feeding, carding, web forming and heat setting process. Since the melting point of the single-component polylactic acid fiber is low, in order to avoid the problems such as melting of the polylactic acid fiber in the processes of opening, carding and heat setting, the original opening mixing and carding and setting processes of the PE / PP hot air nonwoven fabric production are adjusted, the longitudinal and transverse arrangement directions of the fiber in the web are reasonably controlled, including the control of various speed ratios of the cylinder, the working roller and the stripping roller, the cylinder and the doffer, the condensing roller and the doffer, and the selection of the web setting weight. The special process scheme of large pitch, low draft, low speed, light setting weight, weak carding, low tension and multi-stage setting is adopted to further reduce the excessive friction and heat-sensitive brittleness of the fiber. The fiber web with three-dimensional structure of correct fiber arrangement direction, multiple pores and irregular pore distribution is produced from the low-melting polylactic acid fiber and the high-low-melting polylactic acid fiber hot air nonwoven fabric, which ensures the uniformity, thickness, setting weight and longitudinal and transverse strength ratio of the web. The low-melting polylactic acid fiber and the high-low-melting polylactic acid fiber are in a proportion of 30:70.

[0074] The main process parameters are as follows: the beater speed of the opening machine is controlled at 310 r / min during opening, the cotton is mixed by the way of horizontal laying and direct taking during the cotton mixing process, so as to achieve the purpose of fully mixing the low-melting single-component polylactic acid fiber and the high-low-melting polylactic acid fiber, the speed of the even cotton roller is controlled between 197 r / min during the cotton output, the speed of the opening machine is controlled at 610 r / min during the fine opening, the air pressure of the air pressure cotton box is controlled at 4 MPa during the air flow feeding process, the speed of the mixing roller of the air pressure cotton box is controlled at 390 r / min, the speed of the output roller is 20.1 r / min, the linear speed of the cylinder is adjusted at 790 m / min during the carding process, the linear speed of the working roller is controlled at 50.3 m / min, the linear speed of the stripping roller is 132.1 m / min, and the speed of the doffer is controlled at 25.6 m / min. The single-layer web formed after the condensing roller and the stripping roller has a weight of 12.6 g / m 2 . The setting is four-stage flat web oven, the setting temperatures of the four-stage oven are controlled at 105℃, 130℃, 125℃ and 115℃ respectively, the running speed of the web in the oven is 75 m / min, and the weight of the web obtained after the oven is 25.2 g / m 2 low-melting polylactic acid fiber and high-low-melting polylactic acid fiber hot air nonwoven fabric.

[0075] Among the above, the low-melting-point polylactic acid fiber and the high-low-melting-point polylactic acid fiber are specially developed and produced by Suzhou Jinquan New Material Co., Ltd., wherein the high-low-melting-point polylactic acid bicomponent fiber skin layer is a modified polylactic acid component, and the modified components include PHA, PBT, PBS, PBAT, PCL and other biodegradable materials; the preferred modified component in the application is PHA+PBS; in addition, the low-melting-point monocomponent polylactic acid fiber is also a modified fiber, and the modified components include PHA, PBT, PBS, PBAT, PCL and other biodegradable materials; the preferred modified component is PHA, and the modified fiber ratio is PLA:PHA=90:10.

[0076] Among the above, the low-melting-point polylactic acid fiber and the high-low-melting-point polylactic acid fiber are specially developed and produced by Suzhou Jinquan New Material Co., Ltd., wherein the high-low-melting-point polylactic acid bicomponent fiber skin layer is a modified polylactic acid component, and the modified components include PHA, PBT, PBS, PBAT, PCL and other biodegradable materials; the preferred modified component in the application is PHA+PBS; in addition, the low-melting-point monocomponent polylactic acid fiber is also a modified fiber, and the modified components include PHA, PBT, PBS, PBAT, PCL and other biodegradable materials; the preferred modified component is PHA, and the modified fiber ratio is PLA:PHA=90:10.

[0077] The absorbent core layer 2 includes an upper layer, a middle layer and a lower layer, the upper layer is dust-free paper, the middle layer is a polylactic acid fiber flow guide layer containing biodegradable superabsorbent resin, and the bottom layer is a polylactic acid fiber spunlace nonwoven fabric.

[0078] The surface layer of the dust-free paper has a grammage of 38 g / m 2 The dust-free paper is a heat-sealed dust-free paper containing fiber with a ratio of wood pulp fiber: high-low-melting-point polylactic acid bicomponent fiber = 80:20, wherein the length of the high-low-melting-point polylactic acid bicomponent fiber is 4 mm, and the curling degree is 0. The dust-free paper is produced by Jiaxing Shixin Nonwoven Co., Ltd.

[0079] In production, firstly, the lower polylactic acid spunlace nonwoven fabric is unwound, and a layer of high-low melting point polylactic acid fiber and high water absorbing resin mixture is sprayed thereon, the spraying amount is 40 g / m2, wherein the ratio of high-low melting point polylactic acid fiber: high water absorbing resin is: 1:99, and the particle size of the high water absorbing resin is 85 meshes; the polylactic acid fiber high-porosity flow layer material is unwound and laid on the surface of the high-low melting point polylactic acid fiber and high water absorbing resin mixture, and then high water absorbing resin is sprayed thereon, the spraying amount is 75 g / m2, and the particle size of the high water absorbing resin is 65 meshes; the lower polylactic acid spunlace nonwoven fabric and the polylactic acid fiber high-porosity flow layer after spraying are sent to an upper and lower reciprocating vibration type conveying long curtain driven by a transmission device, the conveying long curtain is driven by an eccentric mechanism of a motor to generate excitation force to generate vibration, the vibration intensity can be controlled in the range of 4.5, the vibration frequency that can be generated is 28 Hz, and the amplitude is 3 mm, so that the sprayed high water absorbing resin is better dispersed in the polylactic acid fiber high-porosity flow layer; after the vibration type conveying long curtain, a layer of high-low melting point polylactic acid fiber and high water absorbing resin mixture is sprayed again on the surface of the polylactic acid fiber high-porosity flow layer, the spraying amount is 18 g / m2, wherein the ratio of high-low melting point polylactic acid fiber: high water absorbing resin is: 50:50, and the particle size of the high water absorbing resin is 35 meshes, and finally the upper dust-free paper is unwound as the surface layer of the absorbent.

[0080] The above three-layer composite enters an oven for heat setting and reinforcement, a three-section flat net oven is adopted, the heating temperature in the first section oven is controlled to be 115°C, the heating temperature in the second section oven is controlled to be 130°C, and the heating temperature in the third section oven is controlled to be 115°C, and a three-layer structure of the absorbent layer is obtained after the oven, and the grammage is 206 g / m2.

[0081] The polylactic acid fiber spunlace nonwoven fabric in the above has a grammage of 35 g / m2 2 , and the high melting point polylactic acid fiber is used, the fiber is water-repellent type, the oil content on the surface of the fiber is 0.07%, and the melting point of the high melting point single-component polylactic acid fiber is 160-175 degrees.

[0082] For the low melting point polylactic acid fiber and the high-low melting point polylactic acid double-component fiber, a Lurol PP-14160 type hydrophilic oil is specially added in the spinning oil in the spinning process, which has the functions of single-point multiple hydrophilic and fast water penetration speed, the surface oil content of the low melting point polylactic acid fiber is controlled to be 0.05%, and the surface oil content of the high-low melting point polylactic acid fiber is controlled to be 0.14%. The different oil contents mainly make the single-component polylactic acid fiber better produce the melting and bonding effect in the subsequent processing process.

[0083] Among the above, the polylactic acid fiber high-loft flow guide layer is a flow guide layer with an invention patent exclusively owned by Suzhou Jinquan New Material Co., Ltd. Specifically, it is a high-degradation-rate flow guide layer material and a preparation method thereof, with a patent number of ZL201710096961.0. The superabsorbent resin used in the absorbent core layer is a biodegradable superabsorbent resin of Formosa Plastics Corporation, with a model number of BC706, and a biodegradation rate of 66% (180 days).

[0084] The bottom layer is a composite film of polylactic acid fiber spunlace nonwoven fabric and a degradable polylactic acid modified film with polylactic acid components as the main component, and the modified components are PHA, PBHA, PBS, etc., and the preferred one is PHA. The bottom film with polylactic acid components as the main component is produced by Fujian Lvge Biodegradable Co., Ltd. The polylactic acid fiber spunlace nonwoven fabric composite film has a grammage of 60 g / m2.

[0085] Since the paper diaper is a composite body composed of a plurality of materials, there are also nonwoven fabrics for leak-proof side edges and elastic waistbands. The leak-proof side edges can use polylactic acid fiber spunlace nonwoven fabric composite film with a grammage of 40 g / m2, and the nonwoven fabric for elastic waistbands uses polylactic acid spunbond nonwoven fabric (produced by Shanghai Jingfa Industrial Co., Ltd.) with a grammage of 35 g / m2. Other components include hot melt adhesive, waist paste, magic buckle and rubber band, which account for only about 10.5%, and can be ignored.

[0086] The biodegradable paper diaper includes 100% polylactic acid fiber hot air nonwoven fabric, an absorbent core layer material with polylactic acid as the main component, and polylactic acid fiber spunlace nonwoven fabric composite film, polylactic acid leak-proof side edges and polylactic acid spunbond nonwoven fabric elastic waistband. The above-mentioned materials are processed into biodegradable paper diapers by conventional paper diaper production equipment.

[0087] Example Three

[0088] The biodegradable paper diaper of the present embodiment includes a paper diaper body, a leak-proof side edge, a magic paste and an elastic waistband. The paper diaper body includes a surface layer 1, an absorbent core layer 2 and a barrier bottom film 3. The surface layer 1 is a porous polylactic acid fiber hot air nonwoven fabric. The absorbent core layer 2 includes an upper layer, a middle layer and a lower layer. The upper layer is dust-free paper. The middle layer is a polylactic acid fiber flow guide layer containing biodegradable superabsorbent resin. The lower layer is polylactic acid fiber spunlace nonwoven fabric. The barrier bottom film 3 is a PHA modified polylactic acid film.

[0089] The preparation method of the porous polylactic acid fiber hot air nonwoven fabric used in the surface layer 1 in the present embodiment is as follows:

[0090] The process flow is mixing, coarse opening, cotton mixing, fine opening, air feeding, carding, web forming and heat setting. In order to avoid the melting of the polylactic acid fiber in the process of opening, carding and heat setting, the original PE / PP hot air nonwoven production process of opening mixing and carding and setting is adjusted, the longitudinal and transverse arrangement direction of the fiber in the web is reasonably controlled, including the control of various speed ratios of the cylinder, the working roller and the stripping roller, the cylinder and the doffer, the condensing roller and the doffer, and the selection of the web setting weight. A special process scheme of large pitch, low draft, low speed, light weight, weak carding, low tension and multi-stage setting is adopted to further reduce the excessive friction and heat-sensitive brittleness of the fiber. The produced low-melting single-component polylactic acid fiber and high-low-melting polylactic acid bicomponent fiber hot air nonwoven fabric has a three-dimensional fiber web with correct fiber arrangement direction, more pores and irregular pore distribution, which ensures the uniformity, thickness, weight and longitudinal and transverse strength ratio of the web. The low-melting single-component polylactic acid fiber and the high-low-melting polylactic acid bicomponent fiber are in a ratio of 45:55.

[0091] The main process parameters are as follows: the beater speed of the opening machine is controlled at 250 r / min during opening, the cotton is mixed by the way of horizontal laying and vertical taking during the cotton mixing process, so as to fully mix the low-melting polylactic acid fiber and the high-low-melting polylactic acid fiber, the speed of the even roller is controlled at 180 r / min during the cotton output, the speed of the opening machine is controlled at 550 r / min during the fine opening, the air pressure of the air pressure cotton box is controlled at 3 MPa during the air feeding process, the speed of the mixing roller of the air pressure cotton box is controlled at 310 r / min, the speed of the output roller is controlled at 18.2 r / min, the linear speed of the cylinder is adjusted at 610 m / min during the carding process, the linear speed of the working roller is controlled at 42.5 m / min, the linear speed of the stripping roller is 120.3 m / min, the speed of the doffer is controlled at 20.5 m / min, and the single-layer web formed after the condensing roller and the stripping roller has a weight of 15.4 g / m2. The setting is a four-section flat web oven, the setting temperatures of the four-section oven are controlled at 100℃, 125℃, 120℃ and 110℃ respectively, the running speed of the web in the oven is 70 m / min, and the weight of the web obtained after the oven is 30.8 g / m 2 The low-melting single-component polylactic acid fiber and the high-low-melting polylactic acid bicomponent fiber hot air nonwoven fabric.

[0092] Among the above, the low-melting-point polylactic acid fiber and the high-low-melting-point polylactic acid fiber are specially developed and produced by Suzhou Jinquan New Material Co., Ltd., wherein the high-low-melting-point polylactic acid bicomponent fiber skin layer is a modified polylactic acid component, and the modified components include PHA, PBT, PBS, PBAT, PCL and other biodegradable materials; the preferred modified component in the application is PHA+PBS; in addition, the low-melting-point monocomponent polylactic acid fiber is also a modified fiber, and the modified components include PHA, PBT, PBS, PBAT, PCL and other biodegradable materials; the preferred modified component is PHA, and the modified fiber ratio is PLA:PHA=80:20.

[0093] Among the above, the low-melting-point polylactic acid fiber and the high-low-melting-point polylactic acid fiber are specially developed and produced by Suzhou Jinquan New Material Co., Ltd., wherein the high-low-melting-point polylactic acid bicomponent fiber skin layer is a modified polylactic acid component, and the modified components include PHA, PBT, PBS, PBAT, PCL and other biodegradable materials; the preferred modified component in the application is PHA+PBS; in addition, the low-melting-point monocomponent polylactic acid fiber is also a modified fiber, and the modified components include PHA, PBT, PBS, PBAT, PCL and other biodegradable materials; the preferred modified component is PHA, and the modified fiber ratio is PLA:PHA=80:20.

[0094] The absorbent core layer 2 includes an upper layer, a middle layer and a lower layer, the upper layer is dust-free paper, the middle layer is a polylactic acid fiber flow guide layer containing biodegradable superabsorbent resin, and the bottom layer is a polylactic acid fiber spunlace nonwoven fabric.

[0095] The surface layer is dust-free paper with a grammage of 40 g / m2, and the dust-free paper is heat-sealed dust-free paper containing fiber with a ratio of wood pulp fiber:high-low-melting-point polylactic acid bicomponent fiber=85:25, wherein the high-low-melting-point polylactic acid bicomponent fiber has a length of 6 mm and a crimp degree of 0. The dust-free paper is produced by Jiaxing Shixin Nonwoven Fabric Co., Ltd.

[0096] In production, firstly, the lower polylactic acid spunlace nonwoven fabric is unwound, and a layer of high-low melting point polylactic acid fiber and high water absorbing resin mixture is sprayed thereon, the spraying amount is 50 g / m2, wherein the ratio of high-low melting point polylactic acid fiber: high water absorbing resin is: 1.5:98.5, and the particle size of the high water absorbing resin is 90 meshes; the polylactic acid fiber high-porosity flow layer material is unwound and laid on the surface of the high-low melting point polylactic acid bi-component fiber and high water absorbing resin mixture, then high water absorbing resin is sprayed thereon, the spraying amount is 80 g / m2, and the particle size of the high water absorbing resin is 70 meshes; the lower polylactic acid spunlace nonwoven fabric and the polylactic acid fiber high-porosity flow layer after spraying are sent to an upper and lower reciprocating vibration type conveying long curtain driven by a transmission device, the conveying long curtain is vibrated by generating excitation force through an eccentric mechanism driven by a motor, the vibration intensity can be controlled in the range of 6, the vibration frequency that can be generated is 30 Hz, and the amplitude is 4 mm, so that the sprayed high water absorbing resin is better dispersed in the polylactic acid fiber high-porosity flow layer; after the vibration type conveying long curtain, a layer of high-low melting point polylactic acid bi-component fiber and high water absorbing resin mixture is sprayed again on the surface of the polylactic acid fiber high-porosity flow layer, the spraying amount is 30 g / m2, wherein the ratio of high-low melting point polylactic acid fiber: high water absorbing resin is: 50:50, and the particle size of the high water absorbing resin is 40 meshes, and finally the upper dust-free paper is unwound as the surface layer of the absorbent.

[0097] The above three-layer composite enters an oven for heat setting and reinforcement, a three-section flat net oven is adopted, the heating temperature in the first section oven is controlled to be 120°C, the heating temperature in the second section oven is controlled to be 140°C, and the heating temperature in the third section oven is controlled to be 120°C, and a three-layer structure absorbent layer is obtained after the oven, and the grammage is 240 g / m2.

[0098] The polylactic acid fiber spunlace nonwoven fabric in the above has a grammage of 40 g / m2, and the high melting point single-component polylactic acid fiber is used, the fiber is water-repellent type, the fiber surface oil content is 0.08%, and the melting point of the high melting point single-component polylactic acid fiber is 160-175 degrees.

[0099] For the low melting point single-component polylactic acid fiber and the high-low melting point polylactic acid bi-component fiber, Lurol PP-14160 type hydrophilic oil is specially added in the spinning oil in the spinning process, the low melting point single-component polylactic acid fiber has the functions of single-point multiple hydrophilicity and fast water penetration speed, the surface oil content of the low melting point single-component polylactic acid fiber is controlled to be 0.08%, and the surface oil content of the high-low melting point polylactic acid bi-component fiber is 0.15%. The different oil contents are mainly to make the single-component polylactic acid fiber better melt and bond in the subsequent processing process.

[0100] Among the above, the polylactic acid fiber high-loft flow layer is a flow layer with an invention patent of Suzhou Jinquan New Material Co., Ltd. Specifically, it is a high-degradation-rate flow layer material and a preparation method thereof, and the patent number is ZL201710096961.0. The superabsorbent resin used in the absorbent core layer is a biodegradable superabsorbent resin of Taiwan Plastic Co., Ltd., model BC706, with a biodegradation rate of 66% (180 days).

[0101] The impermeable bottom film 3 is a composite film of polylactic acid fiber spunlace non-woven fabric and degradable polylactic acid modified film with polylactic acid component as the main component. The modified component is PHA, PBHA, PBS, etc., and the preferred one is PHA. The bottom film with polylactic acid component as the main component is produced by Fujian Lvge Biodegradable Co., Ltd. The grammage of the polylactic acid fiber spunlace non-woven fabric composite film is 65 g / m2.

[0102] Since the paper diaper is a composite of multiple materials, there are also non-woven fabrics for leak-proof cuffs and elastic waistbands. The leak-proof cuffs can use polylactic acid fiber spunlace non-woven fabric composite film with a grammage of 40 g / m2, and the non-woven fabric for elastic waistbands uses polylactic acid spunbond non-woven fabric (produced by Shanghai Jingfa Industrial Co., Ltd.) with a grammage of 35 g / m2. Other components include hot melt adhesive, waist stickers, magic buckles, and rubber bands, which account for only about 10.5%, and can be ignored.

[0103] The biodegradable paper diaper includes 100% polylactic acid fiber hot air non-woven fabric, absorbent core layer material with polylactic acid as the main component, and polylactic acid fiber spunlace non-woven fabric composite film, polylactic acid leak-proof cuffs, and polylactic acid spunbond non-woven fabric elastic waistbands. The above-mentioned materials are processed into biodegradable paper diapers by conventional paper diaper production equipment.

[0104] The polylactic acid fiber hot air non-woven fabric surface layer and the prepared biodegradable paper diaper of the above-mentioned embodiments were tested for main performance:

[0105] The detection items include the antibacterial property, air permeability, moisture conductivity, pH value of the polylactic acid fiber hot air non-woven fabric surface layer, the degradation performance, and water absorption rate of the biodegradable paper diaper. The specific test methods are as follows:

[0106] Antibacterial property: GB 15979-2002 (Hygienic Standard for Disposable Hygienic Products).

[0107] Air permeability: tested according to GB / T5453-1997 standard. Adjust the test pressure difference to 60 Pa, and select a nozzle with a diameter of 7 mm.

[0108] Moisture conductivity: tested according to ZB W 04019-1990 standard. The fabric sample size is 25 mm*300 mm, and the water absorption height is measured for 60 s.

[0109] pH value: tested according to the method stipulated in Appendix C of GB / T 8939-2008 standard.

[0110] Water absorption ratio: tested according to the method stipulated in GB / T 8939-2008 standard.

[0111] Permeability: tested according to Appendix A of GB / T 28004-2011.

[0112] Degradability: evaluated according to the method and condition of GB / T 19277-2003 (IDT ISO 14855:1999).

[0113] Test results: see Table 1

[0114] Table 1: Performance test of degradable diaper

[0115]

[0116] The prepared diaper was subjected to degradation experiment, taking Example 1 as an example, according to the method and condition of GB / T 19277-2003 (IDT ISO 14855:1999). Figures 11 to 16 It can be seen that after thirteen weeks of degradation experiment, all of them become less than 10mm fragments, and the degradation experiment is successful.

[0117] Degradation experiment results of the diaper of the present application

[0118]

[0119] The above detailed the preferred embodiments of the present application. It should be understood that those skilled in the art can make many modifications and changes without creative labor according to the concept of the present application. Therefore, any technical solution that can be obtained by logical analysis, reasoning or limited experiment based on the prior art according to the concept of the present application shall be within the protection scope determined by the claims.

Claims

1. A biodegradable diaper, characterized in that, The diaper includes the main body, leak-proof side panels, Velcro straps, and elastic waistband; the main body of the diaper includes a top layer, an absorbent core layer, and a leak-proof bottom film. The surface layer is a porous polylactic acid fiber hot air nonwoven fabric, and the absorbent core layer includes an upper layer, a middle layer and a lower layer; the upper layer is a dust-free paper, the middle layer is a polylactic acid fiber guiding layer containing biodegradable superabsorbent resin, and the lower layer is a polylactic acid fiber spunlace nonwoven fabric. The impermeable bottom membrane is a PHA-modified polylactic acid membrane; The polylactic acid (PLA) fiber hot-air nonwoven fabric is composed of low-melting-point PLA fibers and high- and low-melting-point PLA fibers in a weight ratio of 25-45:55-75, wherein the low-melting-point PLA fibers have a specification of 1.5-3.0D*38mm, and the high- and low-melting-point PLA fibers have a specification of 1.0-2.0D*38mm; the core layer of the high- and low-melting-point PLA fibers is a high-melting-point PLA component, and the sheath layer is a low-melting-point PLA component or a modified PLA component; the low-melting-point PLA fibers are modified PLA components. The modified polylactic acid component used in the modified polylactic acid component includes at least one of PHA, PBT, PBS, PBAT or PCL.

2. The biodegradable diaper according to claim 1, characterized in that, The weight ratio of PLA to PHA in the PHA-modified polylactic acid membrane is 3-7:7-3.

3. The biodegradable diaper according to claim 1, characterized in that, The preparation process of the polylactic acid fiber hot-air nonwoven fabric is as follows: During opening, the opening machine speed is controlled at 250-380 r / min. During blending, a horizontal laying and direct picking method is used. At the exit, the even roller speed is controlled between 180-220 r / min. During fine opening, the opening machine speed is controlled at 550-680 r / min. In the air-feeding process, the air pressure in the air pressure cotton box is controlled between 3-4.8 MPa, the mixing roller speed is controlled between 310-430 r / min, and the exit roller speed is controlled between 18.2-25.5 rpm. In the carding process, the cylinder linear speed is adjusted to 610-750 m / min, the work roller linear speed is controlled at 42.5-58.9 m / min, the stripping roller linear speed is 120.3-141.2 m / min, and the doffer speed is controlled at 20.5-30.6 m / min. The single-layer web weight formed after stripping by the condensing roller and stripping roller is 9.8-15.4 g / min. g / m 2 The shaping process is carried out in a four-section flat mesh drying oven, with the shaping temperatures of the four sections controlled at 100-110°C, 125-135°C, 120-130°C, and 110-120°C respectively. The running speed of the fiber mesh in the oven is 70-80 m / min, and the weight obtained after drying is 19.6-30.8 g / m². 2 Polylactic acid fiber hot-air nonwoven fabric composed of low-melting-point polylactic acid fiber and high- and low-melting-point polylactic acid fiber.

4. The biodegradable diaper according to claim 1, characterized in that, The preparation process of the absorber core layer is as follows: First, the polylactic acid spunlace nonwoven fabric used in the lower layer is unwound, and a layer of high and low melting point polylactic acid fiber and superabsorbent resin mixture is sprayed on it. The spraying amount is 30-50 grams per square meter. The weight ratio of high and low melting point polylactic acid bicomponent fiber to superabsorbent resin is 0.5-1.5: 98.5-99.

5. The particle size of the superabsorbent resin is 80-90 mesh. The high-loft polylactic acid fiber guide layer material is unrolled and laid on the surface of the mixture of high and low melting point polylactic acid fibers and superabsorbent resin. Then, superabsorbent resin is sprayed on it at a rate of 70-80 g / m², with a particle size of 60-70 mesh. The sprayed lower layer of polylactic acid spunlace nonwoven fabric and the high-loft polylactic acid fiber guide layer are then fed together onto a long conveyor curtain driven by a transmission device. The long conveyor curtain is vibrated by an eccentric mechanism driven by a motor. The vibration intensity can be controlled within the range of 3-6, and the vibration frequency is 25-30 Hz with an amplitude of 2-4 mm, so that the sprayed superabsorbent resin is better dispersed within the high-loft polylactic acid fiber guide layer. After exiting the vibrating conveyor curtain, another layer of high and low melting point polylactic acid fiber and superabsorbent resin mixture is sprayed on the surface of the high-loose polylactic acid fiber guide layer. The spraying amount is 15-30 grams per square meter, and the ratio of high and low melting point polylactic acid fiber to superabsorbent resin is 50:

50. The particle size of the superabsorbent resin is 30-40 mesh. Finally, the cleanroom paper is unrolled and used as the top layer of the absorbent; The three layers are then placed together in an oven for heat setting and reinforcement. A three-section flat mesh oven is used, with the heating temperature in the first section controlled at 110-120℃, the heating temperature in the second section controlled at 120-140℃, and the heating temperature in the third section controlled at 110-120℃. After exiting the oven, a three-layer absorption layer is obtained with a basis weight of 180-240 g / m². The polylactic acid fiber spunlace nonwoven fabric has a basis weight of 30-40 g / m². 2 The fiber used is high-melting-point polylactic acid fiber, which is water-repellent and has an oil content of 0.06-0.08% on the fiber surface. The melting point of high-melting-point polylactic acid fiber is 160-175 degrees Celsius.

5. A biodegradable diaper according to claim 4, characterized in that, During the spinning process, the low-melting-point polylactic acid fibers and high- and low-melting-point polylactic acid fibers used contain Lurol PP-14160 hydrophilic oiling agent in the surface oiling agent.

6. A biodegradable diaper according to claim 5, characterized in that, The surface oil content of the low-melting-point polylactic acid fiber is 0.02-0.08%, and the surface oil content of the high- and low-melting-point polylactic acid fiber is 0.12-0.15%.

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