All-bio-based fabric capable of being used for one-way moisture conduction of liquids with different viscosities and preparation method and application thereof

Abstract

The invention relates to the field of textile materials, in particular to a full-bio-based fabric capable of being used for one-way moisture conduction of liquid with different viscosities and a preparation method and application of the full-bio-based fabric. The full-bio-based fabric is of a double-layer composite structure formed by a spunlace non-woven fabric and a melt-blown non-woven fabric in a hot melting and pressing mode, the spunlace non-woven fabric is made of hydrophilic cellulose, and the melt-blown non-woven fabric is made of polypropylene. The melt-blown non-woven fabric is made of bio-based polyurethane; the fiber diameter D1 of the spunlace non-woven fabric is 5-20 microns, the thickness H1 is 0.5-1.0 mm, and the gram weight M1 is 40-80 g / m < 2 >; the fiber diameter D2 of the melt-blown non-woven fabric is 20 [mu] m-60 [mu] m, the thickness H2 of the melt-blown non-woven fabric is 0.05-0.2 mm, the gram weight M2 of the melt-blown non-woven fabric is 10-50g / m < 2 >, d1, H1gt; h2, M1gt; m2. The full-bio-based fabric disclosed by the invention not only has high-flux one-way passing property for sweat (Newtonian fluid), but also has one-way passing property for fluid (non-Newtonian fluid) with certain viscosity; therefore, the composite material has wide application prospects in human body heat and humidity management clothes, sanitary napkins, paper diapers and medical protective materials for moisture conduction and perspiration, blood passing, viscous fluid micro-control and the like.

Description

Technical Field

[0001] The invention relates to the field of textile materials, and in particular to a fully bio-based fabric that can be used for unidirectional moisture conduction of liquids with different viscosities, and a preparation method and application thereof. Background Art

[0002] Unidirectional moisture conduction refers to the unidirectional transmission of liquids, that is, liquids can only be transmitted spontaneously along the thickness direction of the material, or from one side of the material to the other side, but not in the opposite direction. The unidirectional moisture conduction of fabrics has important application value in many fields such as sportswear, outdoor equipment, medical and care products, and protective clothing. However, existing unidirectional moisture conduction textiles have certain defects in application targets, material design, and preparation processes:

[0003] 1) Application target: The application target of current research on unidirectional moisture-conducting textiles has been limited to the directional conduction of liquid water. In fact, in our daily lives, except for water and air, other fluids are basically non-Newtonian fluids, such as blood, lymph and other biological fluids, milk, ink, paint, oil and polymer solutions, etc.

[0004] 2) Material design: A considerable number of unidirectional moisture-conducting textiles are designed and produced using traditional chemical fibers. Chemical fibers have high unit energy consumption, are generally non-recyclable and difficult to degrade naturally, which poses great harm to the ecological environment. This is not conducive to the realization of my country's long-term goals of "carbon peak and carbon neutrality".

[0005] 3) Preparation process: The existing main methods include weaving with hydrophobic and hydrophilic yarns, constructing a hydrophobic layer on a hydrophilic base fiber or fabric by electrospinning, and chemically modifying hydrophilic or water-repellent fabrics to construct the wettability difference of the fabric layer or structure. These methods all involve the use of organic solvents, and electrospinning cannot be mass-produced due to process conditions and processing efficiency limitations.

[0006] For example, patent CN115071232A discloses an intelligent unidirectional moisture-conducting fabric, which processes hydrophilic chemical fiber, hydrophobic chemical fiber and the entangled twisted composite fiber of the two to construct a wetting gradient in the thickness direction of the fabric. Patent CN114379186A discloses a breathable and perspiration-wicking skin-friendly fabric and its preparation method, wherein polyurethane, polylactic acid-glycolic acid copolymer and polyacrylonitrile are dissolved in tetrahydrofuran and prepared by electrostatic spinning to form a multilayer fiber membrane, and finally the skin-friendly layer and the drainage layer are combined by hot pressing to obtain a breathable and perspiration-wicking skin-friendly fabric. Similarly, patent CN116676718A discloses a unidirectional moisture-conducting TPU elastic bandage, which is formed by electrostatic spinning TPU dissolved in DMAc solvent on the surface of a melt-blown non-woven fabric substrate to form a nanofiber membrane, and then hot pressing to obtain an elastic bandage. Patent CN114797282A discloses an antibacterial and antiviral and one-way moisture-conducting composite filter material and its application, which includes a hydrophobic support layer, a filter layer and a hydrophobic protective layer from the inside to the outside, and the filter layer is a conventional melt-blown polypropylene non-woven fabric layer and an antibacterial and antiviral and hydrophilic modified melt-blown polypropylene non-woven fabric layer from the inside to the outside. Patent CN117325526A discloses a TPU composite melt-blown membrane and a composite fabric using the TPU composite melt-blown membrane, which uses the TPU composite melt-blown membrane to composite nylon spandex four-way stretch fabric with good moisture permeability and air permeability and woven / knitted composite base fabric into a whole, so that the composite fabric has good moisture permeability, air permeability, etc. Patent CN105729918A discloses a breathable unidirectional moisture-conducting protective material, in which water-repellent and hydrophilic polymer spinning solutions are electrospun to obtain fibers with different wettability, and then the pure cotton fine yarn high-density fabric is plasma or sanded for use as a water-repellent layer, and polyamide and other chemical fibers are used as lining materials. Finally, the water-repellent layer fabric layer, hot-melt bonding net, electrospun nanofiber layer, secondary hot-melt bonding net and lining are stacked in sequence and pressed to obtain a three-layer breathable unidirectional moisture-conducting protective material. Patent CN205467700U discloses a unidirectional moisture-conducting nonwoven fabric, patent CN116200872A discloses a pure cotton unidirectional moisture-conducting fabric, patent CN113215714A discloses a unidirectional moisture-conducting grey-dyed fabric, patent CN117568970A discloses a method for producing polyester filaments and cellulose yarns and interwoven unidirectional moisture-conducting functional fabrics, patent CN118007442A discloses a unidirectional moisture-conducting fabric and a preparation method thereof, patent CN113564918A discloses a method for preparing a Janus fabric with unidirectional permeability of droplets, and patent CN113308871A discloses a method for preparing a unidirectional moisture-conducting antifouling fabric based on cleaning technology. All of the above patents use chemical treatment methods such as impregnation, spraying and chemical grafting to load low surface energy chemicals on one side of a hydrophilic fabric such as a cotton fabric to construct a multi-layer fabric with different wettability to achieve unidirectional moisture conduction.

[0007] In summary, it is of great significance to develop a functional material that is not only unidirectionally conductive to liquid water, blood and mucus fluids, but also biodegradable and green-recyclable in an environmentally friendly, low-cost and scalable way. Summary of the invention

[0008] Based on the defects of existing one-way moisture-conducting functional fabrics, such as the large amount of petroleum-based chemical fibers used in material design, the chemical treatment processes involving organic solvents in the production process, and the singleness of the application scenarios, which are limited to the one-way conduction of liquid water, the present invention aims to solve the above-mentioned problems existing in the material design, production and application of existing one-way moisture-conducting fabrics, and provide a functional bio-based fabric that not only has one-way conduction of liquid water, blood and mucus fluids, but also has biodegradability and can be processed and produced on a large scale without solvent.

[0009] To achieve the above objectives, on the one hand, the present invention provides a fully bio-based fabric that can be used for unidirectional moisture conduction of liquids with different viscosities. The fully bio-based fabric is a double-layer composite structure formed by a spunlace non-woven fabric and a melt-blown non-woven fabric through a hot-melt pressing technology. The spunlace non-woven fabric is made of hydrophilic cellulose, and the melt-blown non-woven fabric is made of bio-based polyurethane.

[0010] Among them: the fiber diameter D1 of the spunlace nonwoven fabric is 5-20um, the average opening size L1 in the vertical direction of the fabric is 0.1-2um, the thickness H1 is 0.5-1.0mm, and the gram weight M1 is 40-80g / m 2 The fiber diameter D2 of the meltblown nonwoven fabric is 20um-60um, the average opening size L2 in the vertical direction of the fabric is 30-100um, the thickness H2 is 0.05-0.25um, and the gram weight M2 is 10-50g / m 2 , and D2>D1, L2>L1, H1>H2, M1>M2.

[0011] As a further preferred technical solution of the present invention, the molecular weight (Mw) of the bio-based polyurethane is 20,000-120,000 g / mol, and its prepolymer components, polyether / ester polyol and diisocyanate components, are both derived from biomass materials.

[0012] As a further preferred technical solution of the present invention, the hydrophilic cellulose is any one or more of wood cellulose, cotton cellulose, bamboo cellulose, hemp cellulose and grass cellulose.

[0013] According to another aspect of the present invention, the present invention also provides a method for preparing a fully bio-based fabric that can be used for unidirectional moisture conduction of liquids with different viscosities, comprising the following steps:

[0014] S1. Using thermoplastic bio-based polyurethane pellets as raw materials, melt-blown non-woven fabrics are obtained through melt-blown spinning processing technology;

[0015] S2. Adopt the hot melt pressing technology to melt the meltblown non-woven fabric, and then bond it with the spunlace non-woven fabric under pressure to form a laminated fabric, that is, a fully bio-based fabric that can be used for unidirectional moisture conduction of liquids with different viscosities is obtained.

[0016] As a further preferred technical solution of the present invention, the meltblown spinning is processed as follows:

[0017] After the thermoplastic bio-based polyurethane granule is heated, transferred and melted in a twin-screw extruder, the melt stream is extruded from the spinneret holes of the meltblown processing nozzle, and is continuously blown by the hot pressing air flow continuously supplied by the spinneret holes dispersed on the surface of the spinneret plate. The melt is stretched to form microfibers, and then self-adheres and forms on the winding machine to obtain the meltblown non-woven fabric.

[0018] As a further preferred technical solution of the present invention, the diameter of the spinneret holes of the meltblown processing nozzle is 0.2 - 0.3 mm, and the center distance of the spinneret holes is 0.6 - 0.8 mm.

[0019] As a further preferred technical solution of the present invention, the parameters of the meltblown spinning are: the hot air flow pressure is 0.2 - 0.4 MPa, the receiving distance of the winding machine is 20 - 25 cm, and the winding speed is 0.5 - 5 m / min.

[0020] As a further preferred technical solution of the present invention, the parameters of the hot melt pressing are: the temperature T is 120 - 180 °C, the pressure P is 0.05 - 0.5 MPa, and the time t is 1 / 30 min - 10 min.

[0021] As a further preferred technical solution of the present invention, the processing equipment for the hot melt pressing technology is an ironing machine, a hot melt bonding machine, a flat laminating machine, a heat printing machine or a vacuum hot press.

[0022] According to another aspect of the present invention, the present invention also provides an application of the fully bio-based fabric in the unidirectional moisture conduction of non-Newtonian fluids. Compared with Newtonian fluids (such as water), the viscous dissipation of viscous fluids will form a blockage to the liquid transmission. In order to enhance the directional liquid transmission ability from the hydrophobic layer (meltblown non-woven fabric) to the hydrophilic layer (spunlace non-woven fabric), the design of the fully bio-based fabric of the present invention involves the synergistic effect of two gradients: 1) Wettability gradient: from the hydrophobic layer to the hydrophilic layer; 2) Geometric structure (capillary force gradient): D2 > D1 in the fiber diameter and L1 < L2 in the vertical direction between fibers, that is, the bifurcated network structure forms a hierarchical connected pore channel of large pores - small pores.

[0023] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0024] 1. The one-way moisture-conducting all-bio-based fabric of the present invention adopts a spunlace non-woven fabric (also known as a natural cellulose fabric) made of hydrophilic cellulose as a substrate, and a melt-blown non-woven fabric made of bio-based polyurethane (Bio TPU) as a hydrophobic layer. It does not contain other chemical substances. Compared with the traditional petrochemical-based fabric substrate and polyurethane used in the prior art, the all-bio-based fabric has the advantages of reducing carbon emissions, sustainable regeneration of raw materials, green production and biodegradability.

[0025] 2. The present invention adopts a chemical solvent-free processing technology, namely a hot pressing bonding process, which is greener and more environmentally friendly than chemical modifications such as coating and grafting methods used in other inventions; compared with electrospinning technology, the production cost is lower and the efficiency is higher, and it has the advantages of sustainable and large-scale processing and production.

[0026] 3. Compared with other invention technologies that use petroleum-based polyurethane hot melt adhesive webs only as adhesives to laminate and bond multiple layers of fabrics, the present invention is designed with fewer fabric layers, that is, a hydrophilic cellulose spunlace non-woven fabric (also known as natural cellulose fabric) is used as the base material, and a bio-based polyurethane (Bio TPU) meltblown non-woven fabric is used as the hydrophobic layer thereon, which has a simple design and low cost.

[0027] 4. The one-way moisture-conducting functional bio-based fabric of the present invention not only has high-throughput one-way permeability to sweat (Newtonian fluid), but also has one-way permeability to fluids with a certain viscosity (non-Newtonian fluid), which makes it have broad application prospects in human body moisture and heat management clothing, sanitary napkins, diapers and medical protective materials such as moisture conduction and perspiration, blood passage and viscous fluid micro-control. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0029] Figure 1 The natural cellulose fabric and Bio TPU meltblown nonwoven fabric used in the examples and comparative examples of the present invention are real objects and optical microscope pictures, as well as pore size distribution and fabric porosity distribution diagrams. Figures a1 and a2 are real objects of natural cellulose fabric and Bio TPU meltblown nonwoven fabric, respectively; Figures b and c are the corresponding fiber diameter distributions; Figures dg are the Bio TPU weight of 15g / m in Examples 1-4, respectively. 2 , 30g / m 2 , 45g / m 2 , 60g / m 2 Pore ​​size distribution of meltblown microfiber fabric; Figure h is the Bio TPU weight of 15g / m in comparative example 2 2 Pore ​​size distribution of meltblown microfiber fabrics.

[0030] Figure 2The scanning electron microscope optical images, Fourier transform infrared spectrum curves and porosity of the bio-based fabrics are the corresponding functional bio-based fabrics prepared by the hot pressing bonding process in Examples 1-4 of the present invention.

[0031] Figure 3 These are the test results of the unidirectional conductivity of the corresponding functional bio-based fabrics prepared by the hot pressing bonding process in Examples 1-4 and Comparative Examples 1-2 of the present invention to fluids of different viscosities.

[0032] Figure 4 These are the test results of unidirectional permeability and anti-permeability of the corresponding functional bio-based fabrics prepared by the hot-press bonding process in Examples 1-4 of the present invention to fluids with different viscosities.

[0033] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings in conjunction with the embodiments. DETAILED DESCRIPTION

[0034] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0035] Unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. The test reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods, unless otherwise specified, are all conventional methods.

[0036] Embodiment 1:

[0037] 1) Preparation of Bio-based Polyurethane (Bio TPU) Meltblown Nonwoven Fabric

[0038] Bio-based polyurethane with a molecular weight of 60000g / mol (prepolymer components are bio-based PDI, namely 1,5-pentanediisocyanate and sebacic acid polyester polyol and 1,4-butanediol) is used for melt-blowing processing. The processing nozzle (spinneret) of the twin-screw melt-blowing equipment used has a diameter of 0.2mm and a spinneret hole center distance of 0.6mm. First, the polyurethane pellets are dried, and then the pellets are added to the twin-screw feed port to be continuously transferred, melted, and homogenized into a melt by the screw, and then sprayed and stretched under the pressure of the hot gas to form fibers on the automatic receiving device. The temperatures of the five screw processing zones are: 160℃ for zone 1, 190℃ for zone 2, 220℃ for zones 3 and 4, 240℃ for zone 5 (die head), and the screw extrusion speed is 12rpm. The hot air flow pressure of the melt-blowing process is 0.25Mpa, the receiving distance of the winder is 20cm, and the winding speed is 2.4m / min. The final weight of the melt-blown product is 15g / cm 2The Bio TPU meltblown non-woven fabric has a fabric thickness of 0.05um, a fiber diameter of 35um-45um, an average pore size of 81.75um in the vertical direction, and a porosity of 75.88%.

[0039] 2) Hot melt lamination

[0040] The spunlace nonwoven fabric of natural fiber cotton is used as the cellulose fabric substrate and the Bio TPU meltblown nonwoven fabric is composited. The Bio TPU meltblown nonwoven fabric and the spunlace nonwoven fabric are hot-pressed and bonded using a hot-pressing bonding apparatus that can be processed continuously. Specifically, the Bio TPU meltblown nonwoven fabric roll and the spunlace nonwoven fabric roll are placed on the cloth rod 1 and cloth rod 2 respectively, and the pre-pressure of the pressure roller is set to 0.01MPa, the rotation speed is 60rmp, the transmission speed is 2.5m / min, the pressure of the pressure roller in the hot melt bonding area is 0.025MPa, the temperature is 136℃, and the rotation speed is 60rmp. Here, the gram weight of the spunlace nonwoven fabric is 60g / cm 2 The thickness is 0.8mm, the fiber diameter is 10um~15um, the average pore size in the vertical direction is 0.1~2um, and the porosity is 79.44%.

[0041] Through the above-mentioned processing, the final product is a fully bio-based fabric with a Bio TPU meltblown non-woven fabric and a spunlace non-woven fabric weight ratio of 1:4, that is, a Bio TPU content of 20wt%, and a fabric porosity of 71.64%.

[0042] The following Examples 2-4 use Bio TPU with the same components as in Example 1.

[0043] Embodiment 2:

[0044] 1) Preparation of Bio-based Polyurethane (Bio TPU) Meltblown Nonwoven Fabric

[0045] Bio-based polyurethane with a molecular weight of 60000g / mol was used for melt-blowing processing. The processing nozzle diameter of the twin-screw melt-blowing equipment used was 0.2mm, and the center distance of the spinneret hole was 0.6mm. First, the polyurethane pellets were dried, and then the pellets were added to the twin-screw feed port to be continuously transferred, melted, and homogenized into a melt by the screw, and then sprayed and stretched under the pressure of the hot gas to form fibers on the automatic receiving device. The temperatures of the five zones of the screw processing are: 160°C for zone one, 190°C for zone two, 220°C for zones three and four, 240°C for zone five (die head), and the screw extrusion speed is 12rpm. The hot air flow pressure of the melt-blowing process is 0.25Mpa, the receiving distance of the winder is 20cm, and the winding speed is 1.6m / min. The final weight of the melt-blowing process is 30g / cm 2The Bio TPU meltblown non-woven fabric has a fabric thickness of 0.066um, a fiber diameter of 35um-45um, an average pore size of 55.21um in the vertical direction, and a porosity of 50.69%.

[0046] 2) Hot melt lamination

[0047] The spunlace nonwoven fabric of natural fiber cotton is used as the cellulose fabric substrate and composited with Bio TPU meltblown nonwoven fabric. The Bio TPU meltblown nonwoven fabric and cellulose fabric are hot-pressed and bonded (also known as hot melt bonding) using a hot-press bonding apparatus that can be processed continuously. The Bio TPU meltblown nonwoven fabric roll and the spunlace nonwoven cotton fabric roll are placed on cloth rod 1 and cloth rod 2 respectively, and the pre-pressure of the pressure roller is set to 0.01MPa, the rotation speed is 60rmp, the transmission speed is 2.5m / min, the pressure of the pressure roller in the hot melt bonding area is 0.25MPa, the temperature is 136℃, and the rotation speed is 60rmp. The gram weight of the spunlace nonwoven cotton fabric here is 60g / cm 2 , the thickness is 0.8mm, the fiber diameter is 10um~15um, the average pore size in the vertical direction is 0.1~2um, and the porosity is 79.44%.

[0048] Through the above-mentioned processing, the final product is a fully bio-based fabric with a Bio TPU meltblown non-woven fabric and a spunlace non-woven fabric weight ratio of 1:2, that is, a Bio TPU content of 33wt%, and a fabric porosity of 63.47%.

[0049] Embodiment 3:

[0050] 1) Preparation of Bio-based Polyurethane (Bio TPU) Meltblown Nonwoven Fabric

[0051] Bio-based polyurethane with a molecular weight of 60000g / mol was used for melt-blowing processing. The processing nozzle (spinneret) of the twin-screw melt-blowing equipment used had a diameter of 0.2mm and a center distance of 0.6mm for the spinneret holes. First, the polyurethane pellets were dried, and then the pellets were added to the twin-screw feed port to be continuously transferred, melted, and homogenized into a melt by the screw, and then sprayed and stretched under the pressure of the hot gas to form fibers on the automatic receiving device. The temperatures of the five screw processing zones are: 160°C for zone one, 190°C for zone two, 220°C for zones three and four, 240°C for zone five (die head), and the screw extrusion speed is 12rpm. The hot air flow pressure of the melt-blowing process is 0.25Mpa, the receiving distance of the winder is 20cm, and the winding speed is 0.8m / min. The final weight of the melt-blowing process is 45g / cm 2 The Bio TPU meltblown non-woven fabric has a fabric thickness of 0.091um, a fiber diameter of 35um-45um, an average pore size of 43.58um in the vertical direction, and a porosity of 23.26%.

[0052] 2) Hot melt lamination

[0053] The spunlace nonwoven fabric of natural fiber cotton is used as the cellulose fabric substrate and composited with Bio TPU meltblown nonwoven fabric. The Bio TPU meltblown nonwoven fabric and the cellulose fabric are hot-pressed and bonded using a hot-pressing bonding apparatus that can be processed continuously. The Bio TPU meltblown nonwoven fabric and the spunlace nonwoven cotton fabric are rolled onto cloth rods 1 and 2 respectively, and the pre-pressure of the pressure roller is set to 0.01MPa, the rotation speed is 60rmp, the transmission speed is 2.5m / min, the pressure roller pressure in the hot melt bonding area is 0.025MPa, the temperature is 136℃, and the rotation speed is 60rmp. The gram weight of the spunlace nonwoven cotton fabric here is 60g / cm 2 The thickness is 0.8mm, the fiber diameter is 10um~15um, the average pore size in the vertical direction is 0.1~2um, and the porosity is 79.44%.

[0054] Through the above-mentioned processing, the final product is a fully bio-based fabric with a Bio TPU meltblown non-woven fabric and a spunlace non-woven fabric weight ratio of 3:4, that is, a Bio TPU content of 43wt%, and a fabric porosity of 53.12%.

[0055] Embodiment 4:

[0056] 1) Preparation of Bio-based Polyurethane (Bio TPU) Meltblown Nonwoven Fabric

[0057] Bio-based polyurethane with a molecular weight of 60000g / mol was used for melt-blowing processing. The processing nozzle (spinneret) of the twin-screw melt-blowing equipment used had a diameter of 0.2mm and a center distance of 0.6mm for the spinneret holes. First, the polyurethane pellets were dried, and then the pellets were added to the twin-screw feed port to be continuously transferred, melted, and homogenized into a melt by the screw, and then sprayed and stretched under the pressure of the hot gas to form fibers on the automatic receiving device. The temperatures of the five zones of the screw processing are: 160°C for zone one, 190°C for zone two, 220°C for zones three and four, 240°C for zone five (die head), and the screw extrusion speed is 12rpm. The hot air flow pressure of the melt-blowing process is 0.25Mpa, the receiving distance of the winder is 20cm, and the winding speed is 0.4m / min. The final weight of the melt-blown process is 60g / cm 2 The Bio TPU meltblown non-woven fabric has a fabric thickness of 0.117um, a fiber diameter of 35um-45um, an average pore size of 32.98um in the vertical direction, and a porosity of 6.92%.

[0058] 2) Hot melt lamination

[0059] The spunlace nonwoven fabric of natural fiber cotton is used as the cellulose fabric substrate and composited with Bio TPU meltblown nonwoven fabric. The Bio TPU meltblown nonwoven fabric and the cellulose fabric are hot-pressed and bonded using a hot-pressing bonding apparatus that can be processed continuously. The Bio TPU meltblown nonwoven fabric and the spunlace nonwoven cotton fabric are rolled onto cloth rods 1 and 2 respectively, and the pre-pressure of the pressure roller is set to 0.01MPa, the rotation speed is 60rmp, the transmission speed is 2.5m / min, the pressure roller pressure in the hot melt bonding area is 0.025MPa, the temperature is 136℃, and the rotation speed is 60rmp. The gram weight of the spunlace nonwoven cotton fabric here is 60g / cm 2 , thickness is 0.8mm, fiber diameter is 10um~15um. Through the above process, the final product is a Bio TPU meltblown nonwoven fabric with a weight ratio of 1:1 to spunlace nonwoven fabric, that is, a fully bio-based fabric with a Bio TPU content of 50wt%, and a fabric porosity of 40.90%.

[0060] Comparative Example 1:

[0061] In order to compare the unidirectional conductivity of all-biobased fabrics and pure cellulose fabrics to droplets, pure cellulose fabric is used as a blank sample for processing comparison. The cellulose fabric is a spunlace nonwoven fabric of natural fiber cotton with a gram weight of 60g / cm 2 , thickness of 0.8mm, fiber diameter of 10um-15um. The cellulose fabric roll is placed on the cloth rod 1, the pre-pressure of the pressure roller is set to 0.01MPa, the rotation speed is 60rmp, the conveying speed is 2.5m / min, the pre-pressure of the pressure roller in the hot melt bonding area is 0.025MPa, the temperature is 136℃, and the rotation speed is 60rmp, and finally a pure cellulose fabric with a Bio TPU content of 0wt% is obtained.

[0062] Comparative Example 2:

[0063] The unidirectional conductivity of the present invention for viscous droplets is based on the geometric parameters of the Bio TPU meltblown nonwoven fabric. The capillary force brought by these geometric structures can offset the flow dissipation of the viscous fluid, thereby achieving unidirectional moisture conduction. In order to verify the influence of fiber diameter and porosity in the geometric parameters of the meltblown nonwoven fabric on the unidirectional conductivity of different fluids, this comparative example is proposed as a comparative experiment of Example 1, except that the diameter of the processing nozzle (spinneret) of the meltblown spinning is adjusted to 0.1 mm.

[0064] 1) Preparation of Bio-based Polyurethane (Bio TPU) Meltblown Nonwoven Fabric

[0065] Bio-based polyurethane with a molecular weight of 60000g / mol was used for melt-blowing processing. The processing nozzle (spinneret) of the twin-screw melt-blowing equipment used had a diameter of 0.1mm and a center distance of 0.6mm for the spinneret holes. First, the polyurethane pellets were dried, and then the pellets were added to the twin-screw feed port to be continuously transferred, melted, and homogenized into a melt by the screw, and then sprayed and stretched under the pressure of the hot gas to form fibers on the automatic receiving device. The temperatures of the five zones of the screw processing are: 160°C for zone one, 190°C for zone two, 220°C for zones three and four, 240°C for zone five (die head), and the screw extrusion speed is 12rpm. The hot air flow pressure of the melt-blowing process is 0.25Mpa, the receiving distance of the winder is 35cm, and the winding speed is 0.4m / min. The final weight of 15g / cm was obtained through the melt-blowing process. 2 The Bio TPU meltblown nonwoven fabric has a fabric thickness of 0.65um, a fiber diameter of ~4um, an average pore size of 14.87um in the vertical direction, and a porosity of 45.27%.

[0066] 2) Hot melt lamination

[0067] The spunlace nonwoven fabric of natural fiber cotton is used as the cellulose fabric substrate and composited with Bio TPU microfiber. The Bio TPU microfiber and cellulose fabric are hot-pressed and bonded using a hot-press bonding apparatus that can be processed continuously. The Bio TPU microfiber and spunlace nonwoven cotton fabric are rolled onto cloth rods 1 and 2 respectively, and the pre-pressure of the pressure roller is set to 0.01MPa, the rotation speed is 60rmp, the transmission speed is 2.5m / min, the pressure roller pressure in the hot melt bonding area is 0.025MPa, the temperature is 136℃, and the rotation speed is 60rmp. The gram weight of the spunlace nonwoven cotton fabric here is 60g / cm 2 , thickness is 0.8mm, fiber diameter is 10um~15um. Through the above process, the final product is a full bio-based fabric with a weight ratio of Bio TPU melt-blown non-woven fabric to cellulose fabric of 1:4, that is, a Bio TPU content of 20wt%.

[0068] Based on the samples prepared in the above embodiments and comparative examples, the material characterization, performance testing and result analysis are discussed as follows:

[0069] 1. Basic characterization of materials

[0070] Figure 1 The following are the physical objects and optical microscope pictures of the natural cellulose fabric and Bio TPU microfiber used in the embodiments and comparative examples of the present invention, as well as the pore size distribution and fabric porosity distribution diagram. Figure a1 and Figure a2 are the physical pictures of the natural cellulose fabric and Bio TPU microfiber, respectively. Figure 1Figures b and c are the corresponding fiber diameter distributions. It can be seen that the fiber diameter of the spunlace nonwoven cotton fabric is 5um to 25um, with an average diameter of about 15um, and the pores between the fibers are small; while the diameter of the Bio TPU microfiber is 25um to 55um, with an average diameter of about 40um, and the pores between the fibers are slightly larger. Figure 1 The dh in the middle is Bio TPU with a gram weight of 15g / m 2 (Example 1), 30g / m 2 (Example 2), 45g / m 2 (Example 3), 60g / m 2 (Example 4) and 15g / m 2 (Comparative Example 2) Microfiber fabric pore size distribution: It can be seen that as the weight increases, the pores between the fibers gradually become smaller. When the Bio TPU weight is 60g / m 2 The average pore size is 33um, and it tends to form a film after bonding.

[0071] Figure 2 The scanning electron microscope optical pictures of the corresponding functional bio-based fabrics prepared by the hot pressing bonding process in Examples 1-4 of the present invention are shown in FIG. Figure 2 The loading amounts of Bio TPU hot melt adhesive nets in ad are 15g (20wt%), 30g (33wt%), 45g (43wt%) and 60g (50wt%). Fourier transform infrared spectroscopy curves of functional bio-based fabrics ( Figure 2 e) appears at 1720cm -1 The ester group (C=O) of the meltblown nonwoven fabric can be judged to be well combined with the cellulose fabric through the hot pressing bonding process, and there is no new peak migration, indicating that the Bio TPU has not been decomposed in this process. Through the scanning electron microscope image, it can be found that with the increase of the load of the meltblown nonwoven fabric, the pores of the inner layer are reduced and the porosity decreases. When the load is 60g (50wt%), it can be observed that the Bio TPU meltblown nonwoven fabric cross-links into a sealing film and has a certain thickness. In addition, due to the double gradient difference in surface wettability (Bio TPU water-repellent, cellulose fabric hydrophilic) and geometric structure (pore size, porosity) of the three load fabrics, the liquid on the inner layer can penetrate and diffuse to the surface layer under the combined action of gravity, capillary force and surface tension to complete the transfer of fluid. Figure 2 f is the porosity of fabrics with different BioTPU loadings (Examples 1-4), and it can be seen that the gram weight is 60g / m 2 The porosity of the spunlace nonwoven cotton fabric is about 80%. With the increase of Bio TPU loading, the porosity gradually decreases. When the loading is 60g / m 2When the weight of the fabric is 50 wt%, the porosity of the fabric drops below 50%. The above pore size and porosity distribution are all experimental parameter values ​​for the unidirectional conduction of mucus droplets.

[0072] 2. One-way conductivity test of all-biobased fabrics (also known as functional biobased fabrics) for fluids of different viscosities

[0073] In order to study the unidirectional conductivity of functional bio-based fabrics to fluids with different viscosities, four fluids with different viscosities were prepared. Pure water was used as a Newtonian fluid, and then 0.5wt%, 1wt% and 2wt% of sodium carboxymethyl cellulose (CMC-Na) aqueous solutions were prepared respectively: a certain mass fraction of CMC-Na was added to a beaker containing pure aqueous solution at room temperature for mechanical stirring for 6h, and then left to stand for 1h. The CMC-Na aqueous solution has a certain viscosity and is a non-Newtonian fluid. The transfer behavior of droplets in porous media is essentially a physical phenomenon of fluid penetration and diffusion under the combined action of gravity, capillary force and surface tension, so the fluid property indicators related to the above physical forces were tested as shown in Table 1. It can be found that compared with pure water, the density of CMC-Na aqueous solution is almost unchanged, while the surface tension and contact angle change slightly, which does not essentially affect the penetration and diffusion behavior of droplets, but the viscosity changes by an order of magnitude, so the difference in viscous dissipation is the main difference of non-Newtonian fluids. The one-way conductivity test of fluids with different viscosities was conducted by studying the penetration and diffusion behavior of droplets on the horizontally placed fabric surface under quasi-static conditions: the inner layer of the fabric (Bio TPU meltblown nonwoven fabric-hydrophobic layer) was placed horizontally on the absorbent A4 paper with the inner layer of the fabric (pure cellulose fabric-hydrophilic layer) facing upwards. At this time, the outer layer of the fabric (pure cellulose fabric-hydrophilic layer) was in direct contact with the A4 paper. When the quasi-static droplets penetrated the inner layer of the fabric and diffused vertically to the outer layer, the A4 paper would be soaked. The test results are shown in Figure 2. Figure 3 shown.

[0074] Table 1 Physical properties of fluids with different viscosities

[0075]

[0076] like Figure 3 As shown in the figure, the loading amount of Bio TPU meltblown nonwoven fabric, the viscosity of the solution, and the volume of the droplet were studied to determine the unidirectional conduction behavior of different fluids on the surface of functional bio-based fabrics. We can find that:

[0077] 1) Pure cellulose fabric (Comparative Example 1) (Bio TPU meltblown nonwoven fabric loading is 60 g (0 wt%)) has no unidirectional conductivity for fluids of different viscosities and volumes due to the lack of dual gradient differences in surface wettability and geometric structure;

[0078] 2) The functional fabric with a Bio TPU meltblown nonwoven fabric loading of 60 g (50 wt%) (Example 4) undergoes in-situ melting and film formation due to the overloading of the water-repellent meltblown nonwoven fabric on the surface, so that a water-repellent film with almost no pore structure is formed on the surface of the fabric, which makes the fluid impermeable and has no unidirectional conductivity;

[0079] 3) The functional fabrics with Bio TPU meltblown nonwoven fabric loadings of 15g (20wt%), 30g (33wt%) and 45g (43wt%) respectively, due to the double gradient difference in wettability of fabric components and geometric structure (pore size and fiber diameter), the droplets in the inner layer of the fabric can be pumped into the interior of the cellulose fabric under the action of capillary force and gravity and diffuse to the surface of the A4 paper to wet it. When the droplets are placed from the outer layer, due to the strong capillary force of the hydrophilic fiber fabric, the droplets will diffuse laterally inside the cellulose fabric and cannot penetrate and diffuse in the inner layer to wet the A4 paper. Therefore, the above-mentioned functional bio-based fabrics have a certain unidirectional permeability to droplets of different viscosities;

[0080] 4) In addition, according to Figure 3 We can also conclude that increasing the viscosity of the solution, that is, increasing the viscous dissipation, will increase the penetration and diffusion resistance of the fluid inside the fabric, which is not conducive to the unidirectional conduction of the fluid. For example, the functional bio-based fabric with a loading of 20wt% of Bio TPU melt-blown non-woven fabric is Figure 3 From ac, we can see that the former only has unidirectional conductivity for pure water solutions of different volumes, and when the fluid is 0.5wt% CMC-Na solution, it can only unidirectionally conduct 50uL droplets, and has no unidirectional conductivity for 1wt% CMC-Na solution. In addition, Figure 3 It can be seen from the figure that when the loading amount of Bio TPU melt-blown nonwoven fabric is 43wt%, the double gradient difference of the functional bio-based fabric brings the best unidirectional conductivity for droplets of different viscosities;

[0081] 5) Pass Figure 3 In the test results of Comparative Example 2, the same Bio TPU meltblown nonwoven fabric loading, i.e., 15g (20wt%), is used, but the geometric structure parameters of the microfibers are beyond the limits of the present invention. At this time, the bio-based fabric can only achieve unidirectional conduction of Newtonian fluid-water, and the two core indicators of liquid water pipe management ability, the unidirectional transmission index (R) and the comprehensive moisture conduction and quick-drying ability index (OMMC), are only 289.81% and 0.8 respectively. According to the evaluation standard of fabric unidirectional moisture conduction performance (Table 2), it can only be regarded as level 2, which is relatively poor. It is important that the fabric no longer has unidirectional conduction for the fluid of 1wt% CMC-Na solution (non-Newtonian fluid). If the Bio TPU meltblown nonwoven fabric loading or the solution viscosity is increased, such as 2wt% CMC-Na solution, the dissipation effect on viscous droplets will only be worse, and the unidirectional conduction function cannot be achieved.

[0082] 3. Liquid moisture management capability of functional bio-based fabrics - unidirectional moisture conduction / absorption and diffusion performance test

[0083] Take the functional bio-based fabrics prepared in the above Examples 1-4 and the comparative example-pure cellulose fabric, and refer to GB / T21655.2-2019 "Evaluation of Moisture Absorption and Quick-Drying of Textiles Part 2: Dynamic Moisture Transfer Method" and AATCC 195-2009 "Liquid Moisture Management Performance of Textiles" to test the liquid moisture management ability of the fabric. The unidirectional transmission ability of the fabric for liquid water is divided into 1-5 levels, among which 5 is the best, and more than 3 levels are considered to have a unidirectional moisture conduction effect. The test method is to put the sample into the liquid moisture management tester (MMT), with the skin-friendly layer of the sample, i.e. the inner layer (Bio TPU meltblown non-woven fabric-hydrophobic layer) facing up, and the surface layer-pure cellulose fabric facing down. The instrument automatically pumps a certain amount of water droplets (test liquid: 9g / L sodium chloride solution) into the center of the skin-friendly layer of the test fabric. The moisture content on both sides of the fabric can be measured by the sensor. The instrument calculates and compares the mutual transfer of moisture content on the two sides of the fabric according to the change of moisture content on both sides of the fabric over time, and calculates the wetting time, water absorption rate, maximum wetting radius, diffusion rate and unidirectional transmission index of the sample. The test results are shown in Table 2.

[0084] Table 2 Evaluation criteria for one-way moisture conduction performance of fabrics and MMT test results of fabrics in Examples 1-4 and Comparative Examples 1 and 2

[0085]

[0086] The unidirectional transmission index (R) and the comprehensive moisture conduction and quick-drying capacity index (OMMC) are the data systems that come with the MMT instrument. They are obtained through a comprehensive evaluation of various indicators on both sides of the fabric and can directly express the unidirectional moisture conduction performance of the fabric. The R index reflects the cumulative difference in moisture content between the two opposite sides of the fabric. The OMMC value, as a composite liquid moisture management index, is affected by several parameters (such as relative moisture content difference, water absorption rate and water diffusion rate) and represents the overall moisture management ability of the fabric. As shown in the data in Table 2, for the pure cellulose fabric (comparative example), there is almost no difference in the wetting time, water absorption rate, maximum wetting radius and diffusion rate of the inner and outer layers. Therefore, the R value of the pure cellulose fabric is 121.68%, which corresponds to the standard of level 2, and the O value of 0.59 is level 3, that is, the pure cellulose fabric has no unidirectional moisture conduction effect.

[0087] For the functional bio-based fabrics (Examples 1-3) loaded with Bio TPU meltblown non-woven fabrics, the wetting time of the inner layer (>4.5s) is greater than the corresponding surface layer time (<3.0s), indicating that the inner layer absorbs water slowly and most of the water is transferred to the surface layer, while the short wetting time of the surface layer indicates that the water can be absorbed in a short time and cannot flow back to the inner layer; the absorption rate of the inner layer of the functional fabric is <23% / s, which is significantly different from the absorption rate of the surface layer, which is >63% / s, so that its unidirectional moisture conduction performance is greatly improved. The inner layer of the bio-based fabric has a slow absorption rate and is not easy to absorb. The water is transferred to the surface layer of the fabric and is quickly absorbed in the surface layer. The water is transferred from the inner layer to the surface layer, and the difference in wetting radius between the inner layer and the outer layer indicates that the water is not easy to diffuse in the inner layer. And with the increase of the Bio TPU loading, the difference in wetting time, water absorption rate, maximum wetting radius and water diffusivity between the inner and outer layers of the functional fabric continues to expand, indicating that the overall moisture management ability of the fabric is continuously enhanced. The corresponding R values ​​are all >850%, and the OMMC values ​​are all ≥0.9, indicating that the functional bio-based fabrics (Examples 1-3) all have a unidirectional moisture conduction effect and all meet the Level 5 standard, and when the Bio TPU loading is 43wt% (Example 3), the R value and OMMC value reach excellent values ​​of 1393.82% and 0.91, respectively. Therefore, the functional bio-based fabric has excellent unidirectional moisture conduction performance.

[0088] 4. Characteristics of functional bio-based fabrics for unidirectional flow of different viscous liquids and hydrostatic pressure resistance test

[0089] In order to study the characteristics of functional bio-based fabrics for unidirectional conduction of fluids with different viscosities, a bio-based fabric with a loading of 30g (33wt%) of Bio TPU melt-blown nonwoven fabric was used to conduct unidirectional conduction of solutions with different viscosities. The results are shown in Figure 2. Figure 4 ab. First, Figure 4 The difference in wetting area between the inner and outer layers in a indicates that the water droplets hardly spread on the water-repellent inner layer, i.e., the value is less than 0.25 cm 2 When the water droplets penetrate and contact the outer layer of the hydrophilic side - cellulose fabric, the hydrophilic properties of a large number of hydroxyl groups will cause the water droplets to spread. As time goes by, it takes less than 10 seconds to reach the maximum spreading area, which is greater than 2.0 cm 2 When the water droplets are replaced with CMC-Na solution with a certain viscosity, the test results are as follows: Figure 4 As shown in Figure b, for 0.5wt% CMC-Na aqueous solution, the droplet diffusion time is 120s, while for 1wt% and 2wt% CMC-Na aqueous solutions, the droplet diffusion time is 160s and 1350s respectively, that is, the difference in viscous dissipation caused by the difference in fluid viscosity will affect its diffusion speed, and the greater the viscosity, the slower the diffusion. And as the viscosity of the fluid increases, the hysteresis effect caused by the increase in viscous dissipation causes the final diffusion area to gradually decrease.

[0090] In addition, for unidirectional conductive materials, anti-permeability is also necessary. In order to test the anti-permeability of functional bio-based fabrics with different Bio TPU melt-blown non-woven fabric loadings to fluids, a quasi-static fluid pressure test was performed here. Figure 4 As shown in Figure 3, a transparent polycarbonate tube with a length of 40 cm and an inner diameter of 1.2 cm is firmly connected to the fabric. Deionized water is injected into the tube at a rate of 10 uL / s by a micro-injection pump, and the height of the water column H is recorded in real time by a camera, and the permeation threshold height Hp caused by the hydrostatic pressure is determined. When permeation occurs, the liquid injection is stopped immediately, and the recording is continued to observe the decrease of H and determine the permeation stop height Hs. Figure 4 de are the static breakthrough pressure values ​​of the fluid measured by placing a water column on the inner layer of the functional bio-based fabric (the water column contacts the hydrophilic cellulose fabric) and on the surface layer (the water column contacts the water-repellent Bio TPU melt-blown non-woven fabric). Figure 4 As shown in de, in this process, the critical penetration pressure from the inner layer to the surface layer is always smaller than the critical penetration pressure from the surface layer to the inner layer. Figure 4 As shown in Figure d, the breakthrough pressure increases with the increase of Bio TPU loading. For pure cotton fabric, its water penetration resistance is 0. The water penetration resistance of bio-based fabrics with Bio TPU loading of 30g (33wt%) and 45g (43wt%) is above 60mm H2O. For bio-based fabrics with 60g (50wt%) Bio TPU loading, its inner layer is basically a water-repellent sealing film, which has no fluid unidirectional permeability. Therefore, for the water column, whether it contacts the inner layer (cellulose fabric) or the outer layer (Bio TPU meltblown non-woven fabric), it has excellent osmotic pressure resistance. However, since the inner layer of bio-based fabrics, such as Bio TPU meltblown non-woven fabrics with loadings of 15g (20wt%), 30g (33wt%) and 45g (43wt%), has good unidirectional permeability to fluids, it can transfer the liquid in the water column to the outer layer. The results are shown in Figure d. Figure 4 As shown in e, its hydrostatic pressure resistance value is 0. The functional bio-based fabrics with Bio TPU loading of 30g (33wt%) and 45g (43wt%) have good anti-penetration ability.

[0091] Although specific embodiments of the present invention are described above, those skilled in the art should understand that these are merely examples and that various changes or modifications may be made to the embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is limited only by the appended claims.

Claims

1. A fully bio-based fabric that can be used for unidirectional moisture conduction of liquids with different viscosities, characterized in that: The all-biobased fabric is a double-layer composite structure formed by hot-melt pressing of spunlace non-woven fabric and melt-blown non-woven fabric. The spunlace non-woven fabric is made of hydrophilic cellulose, and the melt-blown non-woven fabric is made of bio-based polyurethane. Among them: the fiber diameter D1 of the spunlace nonwoven fabric is 5-20um, the average opening size L1 in the vertical direction of the fabric is 0.1-2um, the thickness H1 is 0.5-1.0mm, and the gram weight M1 is 40-80g / m 2 The fiber diameter D2 of the meltblown nonwoven fabric is 20um-60um, the average opening size L2 in the vertical direction of the fabric is 30-100um, the thickness H2 is 0.05-0.25um, and the gram weight M2 is 10-50g / m 2 , and D2>D1, L2>L1, H1>H2, M1>M2.

2. The all-biobased fabric that can be used for unidirectional moisture conduction of liquids with different viscosities according to claim 1, characterized in that: The molecular weight (Mw) of the bio-based polyurethane is 20,000-120,000 g / mol, and its prepolymer components, polyether / ester polyol and diisocyanate components, are both derived from biomass materials.

3. The all-biobased fabric that can be used for unidirectional moisture conduction of liquids with different viscosities according to claim 1, characterized in that: The hydrophilic cellulose is any one or more of wood cellulose, cotton cellulose, bamboo cellulose, hemp cellulose and grass cellulose.

4. The method for preparing a fully bio-based fabric that can be used for unidirectional moisture conduction of liquids with different viscosities according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1. Using thermoplastic bio-based polyurethane pellets as raw materials, melt-blown non-woven fabrics are obtained through melt-blown spinning processing technology; S2. Use hot melt pressing technology to melt the meltblown nonwoven fabric, and then bond it with the spunlace nonwoven fabric through pressure to form a laminated fabric, that is, a fully bio-based fabric that can be used for unidirectional moisture conduction of liquids of different viscosities.

5. The method for preparing a fully bio-based fabric that can be used for unidirectional moisture conduction of liquids with different viscosities according to claim 4, characterized in that: The melt-blown spinning process is as follows: After the thermoplastic bio-based polyurethane pellets are heated, transferred and melted in a twin-screw extruder, the melt stream is extruded from the spinneret holes of the meltblowing processing nozzle and continuously blown by the hot pressurized airflow continuously supplied by the spinneret holes dispersed on the surface of the spinneret. The melt is stretched to form microfibers, which are then self-bonded and formed on a winder to obtain a meltblown non-woven fabric.

6. The method for preparing a fully bio-based fabric that can be used for unidirectional moisture conduction of liquids with different viscosities according to claim 5, characterized in that: The diameter of the spinneret holes of the melt-blowing processing nozzle is 0.2-0.3 mm, and the center distance of the spinneret holes is 0.6-0.8 mm.

7. The method for preparing a fully bio-based fabric that can be used for unidirectional moisture conduction of liquids with different viscosities according to claim 4 or 5, characterized in that: The parameters of the melt-blown spinning process are: hot air flow pressure of 0.2-0.4 MPa, a receiving distance of the winder of 20-25 cm, and a winding speed of 0.5-5 m / min.

8. The method for preparing a fully bio-based fabric that can be used for unidirectional moisture conduction of liquids with different viscosities according to claim 4, characterized in that: The parameters of hot melt pressing are: temperature T is 120-180°C, pressure P is 0.05-0.5MPa, and time t is 1 / 30min-10min.

9. The method for preparing a fully bio-based fabric that can be used for unidirectional moisture conduction of liquids with different viscosities according to claim 4, characterized in that: The processing equipment for hot melt lamination technology is a hot press, hot melt bonding machine, flat bed laminating machine, hot printing machine or vacuum heat press machine.

10. Use of the all-biobased fabric capable of unidirectionally conducting moisture for liquids of different viscosities as claimed in any one of claims 1 to 3 in unidirectionally conducting moisture for non-Newtonian fluids.

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