A fully biodegradable anti-backflow directional water transmission composite material and its preparation method and application

Abstract

The present invention discloses a fully biodegradable anti-backflow directional water transfer composite material and its preparation method and application. The preparation method comprises the following steps: (1) adding a hydrophilic modifier to plant fiber pulp with a beating degree of 18°SR to 55°SR as a hydrophilic layer raw material; uniformly mixing the plant fiber pulp with a beating degree of 18°SR to 55°SR with polylactic acid as a transfer layer raw material; then using a papermaking machine to make paper in one go, with the upper layer of the paper sheet being the hydrophilic layer and the lower layer being the transfer layer; (2) compounding the transfer layer of the paper with a polylactic acid non-woven fabric as a hydrophobic layer, and pressing to obtain a fully biodegradable anti-backflow directional water transfer composite material. The provision of the transfer layer in the present invention gives the material excellent anti-backflow performance and one-way transport performance, and can be used in aspects such as waterproof fabrics.

Description

Technical Field

[0001] The present invention belongs to the field of fabric water management, and particularly relates to a completely biodegradable backflow-proof directional water transmission composite material and a preparation method and application thereof. Background Art

[0002] In hot climates, the moisture absorption and perspiration-wicking properties of clothing can bring people a comfortable and refreshing experience. Functional textiles with moisture absorption technology can provide a quick drying effect in a hot and humid environment by transporting liquid water (such as sweat) and water vapor from the human body to the environment, thereby creating a comfortable experience. With the intensification of the greenhouse effect caused by human industrial activities and environmental damage, the demand for quick drying performance of clothing is increasing, which has prompted researchers to continuously work on improving the moisture absorption properties of textiles. The materials on the market today can provide different levels of moisture absorption capacity, but their moisture transfer is bidirectional and there is no prevention of reverse water penetration, which means that during the moisture transfer process, the inside of the textile will still be wetted and attached to the body. Therefore, it is necessary to develop functional fabrics with directional water transport (DWT) properties.

[0003] Unlike materials with uniform wettability, materials with unidirectional transport properties are able to exhibit unidirectionality because they are constructed based on a wettability gradient. The wettability gradient is the driving force for the spontaneous movement of liquid on both sides of the material. The driving force comes from three aspects: first, the driving effect of the lyophobic layer. The breakthrough pressure from the lyophobic layer to the lyophilic layer is much lower than in the opposite direction; second, the capillary force of the lyophilic layer, which has a push-pull induction effect on the liquid from the lyophobic layer to the lyophilic layer; and finally, the pressure difference generated by the curved liquid surface. Therefore, the driving force generated by the gravity of the droplet and the wettability gradient can drag the liquid from the lyophobic layer to the pore section of the lyophilic layer. The lyophilic pores then pull the liquid toward the lyophilic layer, resulting in a directional transfer of the liquid, which cannot move in the opposite direction without applying external force. Therefore, the development of a new directional water-conducting material has good application prospects. Summary of the Invention

[0004] The primary purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to provide a method for preparing a fully biodegradable anti-backflow directional water transport composite material.

[0005] Another object of the present invention is to provide a completely biodegradable anti-backflow directional water transmission composite material prepared by the method.

[0006] Another object of the present invention is to provide an application of the fully biodegradable anti-backflow directional water transmission composite material.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] A method for preparing a fully biodegradable anti-backflow directional water transmission composite material comprises the following steps:

[0009] (1) adding a hydrophilic modifier to a plant fiber pulp with a beating degree of 18°SR to 55°SR, stirring and mixing uniformly to obtain a hydrophilic layer raw material; uniformly mixing the plant fiber pulp with a beating degree of 18°SR to 55°SR and polylactic acid to obtain a transfer layer raw material; and then using a papermaking machine to make paper in one step, wherein the upper layer of the paper sheet is the hydrophilic layer and the lower layer is the transfer layer, thereby obtaining paper;

[0010] (2) The transfer layer of paper is compounded with a polylactic acid nonwoven fabric as a hydrophobic layer, and a completely biodegradable anti-backflow directional water transfer composite material is obtained by pressing.

[0011] The hydrophilic modifier described in step (1) is at least one of guar gum and carboxymethyl cellulose; preferably guar gum; when used, the hydrophilic modifier can be first diluted with water to form an aqueous solution with a mass percentage of 0.5-3% (preferably 0.8-1.2%), and then added to the plant fiber pulp.

[0012] The amount of the hydrophilic modifier in step (1) is 0.1 to 8% of the mass (absolute dry) of the plant fiber pulp; preferably 1.2 to 1.6% of the mass (absolute dry) of the plant fiber pulp.

[0013] The plant fiber pulp described in step (1) is a bleached pulp of coniferous wood, broadleaved wood, bamboo or other types of plant fibers, or an unbleached pulp of coniferous wood, broadleaved wood, bamboo or other types of plant fibers; preferably, it is at least one of bleached coniferous wood pulp, unbleached coniferous wood pulp, bleached broadleaved wood pulp, unbleached broadleaved wood pulp, bleached bamboo pulp and unbleached bamboo pulp; more preferably, it is at least one of bleached coniferous wood pulp, unbleached coniferous wood pulp and bleached bamboo pulp.

[0014] The beating degree of the plant fiber pulp in step (1) is preferably 28°SR to 42°SR.

[0015] The stirring time in step (1) is 20 to 30 minutes, preferably 20 minutes.

[0016] The polylactic acid described in step (1) is at least one of polylactic acid chopped fibers and polylactic acid particles; preferably, it is at least one of polylactic acid chopped fibers with an average length of 0.5 mm to 8 mm and polylactic acid particles with a particle size of 100 mesh to 1800 mesh; more preferably, it is at least one of polylactic acid chopped fibers with an average length of 5 mm and polylactic acid particles with a particle size of 800 mesh.

[0017] The mass ratio of the plant fiber pulp to the polylactic acid in step (1) is (4:6) to (9:1); preferably (5:5) to (7:3).

[0018] The papermaking machine described in step (1) is a double-layer fourdrinier papermaking machine or a cylinder papermaking machine.

[0019] The conditions for the composite pressing in step (2) are: temperature 30-100° C., line pressure 5-100 kN / m; preferably: temperature 30-50° C., line pressure 10-20 kN / m.

[0020] The hydrophilic layer in the fully biodegradable anti-backflow directional water transmission composite material described in step (2) is 20 to 120 g / m 2 (Preferably 50 to 70 g / m 2 ), the transfer layer is 10-120g / m 2 (Preferably 50 to 60 g / m 2 ), the quantitative weight of polylactic acid non-woven fabric is 15-200g / m 2 (Preferably 50 to 70 g / m 2 ).

[0021] A completely biodegradable backflow-proof directional water transmission composite material is prepared by any of the methods described above.

[0022] The fully biodegradable anti-backflow directional water transmission composite material is used in the preparation of waterproof fabrics or clothing (clothing) with waterproof function.

[0023] The clothing with waterproof function includes underwear or quick-drying clothing for exercise and the like.

[0024] The present invention has the following advantages and effects compared to the prior art:

[0025] 1. The present invention uses plant fiber pulp with a hydrophilic modifier as the hydrophilic layer, and a composite layer of plant fiber pulp and polylactic acid as the transfer layer. The paper is made into paper in one step using a traditional papermaking method, with the upper layer of the paper sheet being the hydrophilic layer and the lower layer being the transfer layer. The paper is then composited with a polylactic acid non-woven fabric as the hydrophobic layer, and subjected to composite pressing to obtain a completely biodegradable anti-backflow directional water transfer composite material. That is, in order to increase the breakthrough pressure from the lyophilic layer to the lyophobic layer, the present invention adds a transfer layer between the hydrophilic layer and the hydrophobic layer, thereby improving the material's ability to prevent moisture backflow.

[0026] 2. The present invention utilizes the different wetting properties of plant fibers and polylactic acid to generate a wetting gradient. The designed three-layer structure is that the plant fiber layer serves as the hydrophilic layer (upper layer), the plant fiber and polylactic acid composite layer serves as the transfer layer (middle layer), and the polylactic acid non-woven fabric serves as the hydrophobic layer (bottom layer). The setting of the transfer layer gives the material excellent anti-backflow performance and one-way transport performance.

[0027] 3. The raw materials (plant fiber and polylactic acid) and auxiliary materials used in the present invention are completely biodegradable. The prepared directional moisture transfer material is completely biodegradable, and polylactic acid has good biocompatibility. Plant fiber, because of its rich hydrogen bonds, can absorb a large amount of water molecules and has good water absorption. Therefore, applying plant fiber and polylactic acid to Janus membrane technology can make good use of the characteristics of both to prepare a new three-layer structure directional water transfer membrane.

[0028] 4. The present invention uses substrates with different hydrophilicities to construct a wettability gradient; constructs a pore size gradient by controlling the beating degree; and adds a transfer layer to prevent water backflow, all of which improve its unidirectional water-conducting performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a graph showing the original test data results of the directional water transport composite material prepared in Example 3.

[0030] Figure 2 This is a graph showing the results of the directional water transport time of the directional water transport composite materials prepared in Examples 1 to 5.

[0031] Figure 3 This is a physical picture of the directional water transport composite material prepared in Example 5. DETAILED DESCRIPTION

[0032] The present invention will be described in further detail below in conjunction with the examples, but embodiments of the present invention are not limited thereto. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art. The test methods in the following examples where specific experimental conditions are not specified are generally based on conventional experimental conditions. Unless otherwise specified, the reagents and raw materials used in the present invention can be obtained commercially.

[0033] The bleached softwood pulp involved in the examples and comparative examples of the present invention is Stone brand, purchased from SMURFIT-STONE Contanier Co., Ltd.; the unbleached softwood pulp is purchased from Shandong Sun Paper Co., Ltd.; and the bleached bamboo pulp is purchased from Sichuan Yongfeng Paper Co., Ltd.

[0034] The polylactic acid involved in the embodiments and comparative examples of the present invention includes polylactic acid fibers and polylactic acid particles, wherein the average length of the polylactic acid fibers (polylactic acid chopped fibers) is 0.5 mm to 8 mm; the particle size of the polylactic acid particles is 100 mesh to 1800 mesh, all of which were purchased from Zhejiang Haining Saiyoupu Chemical Technology Co., Ltd.

[0035] The polylactic acid nonwoven fabrics involved in the examples and comparative examples of the present invention were purchased from Hengtian Changjiang Biomaterials Co., Ltd. with a quantitative weight of 15 to 200 g / m 2 .

[0036] Example 1

[0037] A method for preparing a fully biodegradable anti-backflow directional water transmission composite material comprises the following steps:

[0038] (1) beating bleached softwood pulp to 28°SR for later use;

[0039] (2) preparing guar gum into an aqueous solution with a concentration of 0.8% by mass (the solvent is deionized water, the same below) for standby use;

[0040] (3) adding the guar gum solution prepared in step (2) to the bleached softwood pulp with a beating degree of 28°SR prepared in step (1) in an amount of 1.2 wt% (the absolute dry mass ratio of guar gum to the bleached softwood pulp with a beating degree of 28°SR), and stirring for 20 minutes to prepare the hydrophilic layer raw material for later use;

[0041] (4) The bleached softwood pulp with a beating degree of 28°SR prepared in step (1) and the polylactic acid fiber are uniformly mixed in a ratio of bleached softwood pulp: polylactic acid fiber = 5:5 (absolute dry mass ratio), and the polylactic acid fiber has an average length of 5 mm, and used as the transfer layer raw material for standby use;

[0042] (5) A double-layer fourdrinier papermaking machine or a rotary papermaking machine is used to make paper in one step, and the paper sheet has a double-layer structure; wherein the upper layer of the paper sheet is a hydrophilic layer, the slurry is the hydrophilic layer raw material prepared in step (3), and the hydrophilic layer is 50g / m 2 The lower layer is the transfer layer, the slurry is the transfer layer raw material prepared in step (4), and the transfer layer is quantitatively 50g / m 2 ;After being formed, pressed, dried and curled, it is ready for use;

[0043] (6) Polylactic acid nonwoven fabric is used as the hydrophobic layer, and the hydrophobic layer is quantitatively 50g / m 2 The paper produced in step (5) is compounded with a polylactic acid nonwoven fabric as a hydrophobic layer, and the polylactic acid nonwoven fabric is laminated with the transfer layer of the paper produced in step (5). The composite material is then pressed at a temperature of 30° C. and a linear pressure of 10 kN / m.

[0044] Example 2

[0045] A method for preparing a fully biodegradable anti-backflow directional water transmission composite material comprises the following steps:

[0046] (1) beating bleached softwood pulp to 34°SR and setting aside;

[0047] (2) preparing guar gum into an aqueous solution with a concentration of 1.0% by mass for standby use;

[0048] (3) adding the guar gum solution prepared in step (2) to the bleached softwood pulp with a beating degree of 34°SR prepared in step (1) in an amount of 1.4 wt% (the absolute dry mass ratio of guar gum to the bleached softwood pulp with a beating degree of 28°SR), and stirring for 20 minutes to prepare the hydrophilic layer raw material for later use;

[0049] (4) The bleached softwood pulp with a beating degree of 34°SR prepared in step (1) and the polylactic acid fiber are uniformly mixed in a ratio of bleached softwood pulp: polylactic acid fiber = 6:4 (absolute dry mass ratio), and the polylactic acid fiber has an average length of 5 mm, and used as the transfer layer raw material for standby use;

[0050] (5) A double-layer fourdrinier papermaking machine or a rotary papermaking machine is used to make paper in one step, and the paper sheet has a double-layer structure; wherein the upper layer of the paper sheet is a hydrophilic layer, the slurry is the hydrophilic layer raw material prepared in step (3), and the hydrophilic layer is 60g / m 2 The lower layer is the transfer layer, the slurry is the transfer layer raw material prepared in step (4), and the transfer layer is quantitatively 60g / m 2 ;After being formed, pressed, dried and curled, it is ready for use;

[0051] (6) Polylactic acid nonwoven fabric is used as the hydrophobic layer, and the hydrophobic layer is quantitatively 50g / m 2 The paper produced in step (5) is compounded with a polylactic acid nonwoven fabric as a hydrophobic layer, and the polylactic acid nonwoven fabric is laminated with the transfer layer of the paper produced in step (5). The composite material is then pressed at a temperature of 30° C. and a linear pressure of 10 kN / m.

[0052] Example 3

[0053] A method for preparing a fully biodegradable anti-backflow directional water transmission composite material comprises the following steps:

[0054] (1) beating bleached softwood pulp to 38°SR for later use;

[0055] (2) preparing guar gum into an aqueous solution with a concentration of 1.0% by mass for standby use;

[0056] (3) adding the guar gum solution prepared in step (2) to the bleached softwood pulp with a beating degree of 38°SR prepared in step (1) in an amount of 1.6 wt% (the absolute dry mass ratio of guar gum to the bleached softwood pulp with a beating degree of 28°SR), and stirring for 20 minutes to prepare the hydrophilic layer raw material for later use;

[0057] (4) The bleached softwood pulp with a beating degree of 38°SR prepared in step (1) and the polylactic acid particles with a particle size of 800 mesh are uniformly mixed in a ratio of bleached softwood pulp: polylactic acid particles = 7:3 (absolute dry mass ratio) to serve as the transfer layer raw material for later use;

[0058] (5) A double-layer fourdrinier papermaking machine or a rotary papermaking machine is used to make paper in one step, and the paper sheet has a double-layer structure; wherein the upper layer of the paper sheet is a hydrophilic layer, the slurry is the hydrophilic layer raw material prepared in step (3), and the hydrophilic layer is 60g / m 2 The lower layer is the transfer layer, the slurry is the transfer layer raw material prepared in step (4), and the transfer layer is quantitatively 60g / m 2 ;After being formed, pressed, dried and curled, it is ready for use;

[0059] (6) Polylactic acid nonwoven fabric is used as the hydrophobic layer, and the hydrophobic layer is quantitatively 60g / m 2 The paper produced in step (5) is compounded with a polylactic acid nonwoven fabric as a hydrophobic layer, and the polylactic acid nonwoven fabric is laminated with the transfer layer of the paper produced in step (5). The composite material is then pressed at a temperature of 40° C. and a linear pressure of 20 kN / m.

[0060] Example 4

[0061] A method for preparing a fully biodegradable anti-backflow directional water transmission composite material comprises the following steps:

[0062] (1) beating unbleached softwood pulp to 42°SR for later use;

[0063] (2) preparing guar gum into an aqueous solution with a concentration of 1.2% by mass for subsequent use;

[0064] (3) adding the guar gum solution prepared in step (2) to the unbleached coniferous wood pulp with a beating degree of 42°SR prepared in step (1) in an amount of 1.6 wt% (the absolute dry mass ratio of guar gum to the unbleached coniferous wood pulp with a beating degree of 42°SR), and stirring for 20 minutes to prepare the hydrophilic layer raw material for later use;

[0065] (4) The unbleached softwood pulp with a beating degree of 42°SR prepared in step (1) and the polylactic acid fiber are uniformly mixed in a ratio of unbleached softwood pulp: polylactic acid fiber = 7:3 (absolute dry mass ratio), and the polylactic acid fiber has an average length of 5 mm, and used as the transfer layer raw material for standby use;

[0066] (5) A double-layer fourdrinier papermaking machine or a rotary papermaking machine is used to make paper in one step, and the paper sheet has a double-layer structure; wherein the upper layer of the paper sheet is a hydrophilic layer, the slurry is the hydrophilic layer raw material prepared in step (3), and the hydrophilic layer is 60g / m 2 The lower layer is the transfer layer, the slurry is the transfer layer raw material prepared in step (4), and the transfer layer is quantitatively 50g / m 2 ;After being formed, pressed, dried and curled, it is ready for use;

[0067] (6) Polylactic acid nonwoven fabric is used as the hydrophobic layer, and the hydrophobic layer is quantitatively 60g / m 2 The paper produced in step (5) is compounded with a polylactic acid nonwoven fabric as a hydrophobic layer, and the polylactic acid nonwoven fabric is laminated with the transfer layer of the paper produced in step (5). The composite material is then pressed at a temperature of 40° C. and a linear pressure of 20 kN / m.

[0068] Example 5

[0069] A method for preparing a fully biodegradable anti-backflow directional water transmission composite material comprises the following steps:

[0070] (1) beating bleached bamboo pulp to 38°SR and set aside;

[0071] (2) preparing guar gum into an aqueous solution with a concentration of 1.2% by mass for subsequent use;

[0072] (3) adding the guar gum solution prepared in step (2) to the bleached bamboo pulp with a beating degree of 38°SR prepared in step (1) in an amount of 1.6 wt% (the absolute dry mass ratio of guar gum to the bleached bamboo pulp with a beating degree of 38°SR), and stirring for 20 minutes to prepare the hydrophilic layer raw material for later use;

[0073] (4) The bleached bamboo pulp with a beating degree of 38°SR prepared in step (1) and the polylactic acid fiber are uniformly mixed in a ratio of bleached bamboo pulp: polylactic acid fiber = 7:3 (absolute dry mass ratio), and the polylactic acid fiber has an average length of 5 mm, and used as the transfer layer raw material for standby use;

[0074] (5) A double-layer fourdrinier papermaking machine or a rotary papermaking machine is used to make paper in one step, and the paper sheet has a double-layer structure; wherein the upper layer of the paper sheet is a hydrophilic layer, the slurry is the hydrophilic layer raw material prepared in step (3), and the hydrophilic layer is 70g / m 2 The lower layer is the transfer layer, the slurry is the transfer layer raw material prepared in step (4), and the transfer layer is quantitatively 60g / m 2 ;After being formed, pressed, dried and curled, it is ready for use;

[0075] (6) Polylactic acid nonwoven fabric is used as the hydrophobic layer, and the hydrophobic layer is quantitatively 70g / m2 The paper produced in step (5) is compounded with the polylactic acid nonwoven fabric as a hydrophobic layer, and the polylactic acid nonwoven fabric is laminated with the transfer layer of the paper produced in step (5). The composite material is then pressed at a temperature of 50°C and a linear pressure of 20 kN / m. Figure 3 shown.

[0076] Comparative Example 1

[0077] A method for preparing a fully biodegradable material comprises the following steps:

[0078] (1) beating bleached softwood pulp to 28°SR for later use;

[0079] (2) preparing guar gum into an aqueous solution with a concentration of 0.8% by mass for standby use;

[0080] (3) adding the guar gum solution prepared in step (2) to the bleached softwood pulp in step (1) in an amount of 1.2 wt% (the absolute dry mass ratio of guar gum to bleached softwood pulp with a beating degree of 28° SR), and stirring for 20 minutes to prepare the mixture as a raw material for later use;

[0081] (4) The raw material in step (3) is made into paper using a fourdrinier papermaking machine with a basis weight of 150 g / m 2 After forming, pressing, drying and curling, the composite material is pressed at a temperature of 30°C and a line pressure of 10 kN / m.

[0082] Comparative Example 2

[0083] A method for preparing a fully biodegradable anti-backflow directional water transmission composite material comprises the following steps:

[0084] (1) beating bleached softwood pulp to 28°SR for later use;

[0085] (2) preparing guar gum into an aqueous solution with a concentration of 0.8% by mass for standby use;

[0086] (3) adding the guar gum solution prepared in step (2) to the bleached softwood pulp in step (1) in an amount of 1.2 wt% (the absolute dry mass ratio of guar gum to bleached softwood pulp with a beating degree of 28° SR), and stirring for 20 minutes to prepare the mixture as a raw material for later use;

[0087] (4) using a double-layer fourdrinier papermaking machine or a rotary papermaking machine to make paper from the raw materials in step (3); the paper is a double-layer structure, and the surface layer and the bottom layer of the paper are both made of the raw materials prepared in step (3); the surface layer and the bottom layer are both 50g / m 2 , after being formed, pressed, dried and curled for use;

[0088] (5) Polylactic acid nonwoven fabric is used as the hydrophobic layer, and the hydrophobic layer is quantitatively 50g / m 2 The paper produced in step (4) is compounded with the polylactic acid nonwoven fabric as a hydrophobic layer, and then the composite material is pressed at a temperature of 50° C. and a linear pressure of 10 kN / m.

[0089] Comparative Example 3

[0090] A method for preparing a fully biodegradable anti-backflow directional water transmission composite material comprises the following steps:

[0091] (1) beating bleached softwood pulp to 28°SR for later use;

[0092] (2) The bleached softwood pulp with a beating degree of 28°SR in step (1) and the polylactic acid fiber are uniformly mixed in a ratio of bleached softwood pulp: polylactic acid fiber = 5:5 (absolute dry mass ratio), and the polylactic acid fiber has an average length of 5 mm, and the mixture is used as a raw material for later use;

[0093] (3) using a double-layer fourdrinier papermaking machine or a rotary papermaking machine to make paper from the raw materials in step (2); the paper is a double-layer structure, and the surface layer and the bottom layer of the paper are both made of the raw materials prepared in step (2); the surface layer and the bottom layer are both 50g / m 2 , after being formed, pressed, dried and curled for use;

[0094] (4) Polylactic acid nonwoven fabric is used as the hydrophobic layer, and the hydrophobic layer is quantitatively 50g / m 2 The paper produced in step (3) is compounded with the polylactic acid nonwoven fabric as a hydrophobic layer, and then the composite material is pressed at a temperature of 50° C. and a linear pressure of 10 kN / m.

[0095] Effect embodiment

[0096] (1) Test method

[0097] The one-way transfer index, diffusion area of the upper and lower surfaces, water transfer time, and breakthrough pressure of the fully biodegradable anti-backflow directional water transfer composite materials prepared in Examples 1 to 5 and the materials prepared in Comparative Examples 1 to 3 were measured.

[0098] The unidirectional transfer index and the diffusion area of the upper and lower surfaces are determined according to GB / T21655.2-2019 "Evaluation of Moisture Absorption and Quick-drying Properties of Textiles Part 2: Dynamic Moisture Transfer Method".

[0099] The water transport time test method is as follows: The water transport time is measured using an optical contact angle / surface tension meter. The time is measured from the moment the water droplet contacts the directional water transport film until the water contact angle reaches 0°. Three replicates are set.

[0100] The breakthrough pressure is obtained by measuring the maximum water column height that the material can withstand. During the measurement process, water is added at a rate of 20 mL min -1 Load the material onto one side of the membrane at a flow rate of 100 nm and record the minimum pressure at which water begins to penetrate the membrane as the breakthrough pressure. Repeat three times.

[0101] (2) Test results

[0102] The one-way transmission index is an important indicator to measure the unidirectional water conduction ability of a material. The one-way transmission index is shown in Table 1. The area of water diffusion on the upper and lower surfaces of the material will also directly affect the wearing comfort of the user. The diffusion area of the upper and lower surfaces of the material is shown in Table 2. The directional water transmission time is shown in Table 3. In order to prove that water is prevented from passing through the three-layer fiber membrane in the reverse direction, the penetration pressure from the polylactic acid side (positive direction) and the plant fiber side (reverse direction) was measured, and the results are shown in Table 4. The original test data results of the directional water transmission composite material prepared in Example 3 are shown in Table 4. Figure 1 As shown, the directional water transport time of the directional water transport composite materials prepared in Examples 1 to 5 is as follows Figure 2 As shown. The results show that the water-transmitting composite materials prepared in Examples 1 to 5 all have excellent unidirectional water-conducting properties. This is because the prepared materials use substrates with different hydrophilicities to construct a wettability gradient, and by controlling the beating degree to construct a pore size gradient. In addition, a transfer layer is added to prevent water backflow, all of which improve their unidirectional water-conducting performance. However, the unidirectional water-conducting ability of the material prepared in Comparative Example 1 is too poor. Therefore, the three indicators of unidirectional transfer index, water transfer time, and directional breakthrough pressure cannot be detected.

[0103] Table 1 One-way transfer index of directional water-conducting materials

[0104] Material Single transmission index (%) Example 1 620.35 Example 2 767.58 Example 3 903.04 Example 4 1182.4 Example 5 1067.88 Comparative Example 1 —— Comparative Example 2 540.32 Comparative Example 3 520.35

[0105] Table 2 Diffusion area of upper and lower surfaces of directional water guide materials

[0106]

[0107]

[0108] Table 3 Moisture transfer time of directional water-conducting materials

[0109] Material Moisture transfer time (s) Example 1 1.15 Example 2 0.72 Example 3 0.48 Example 4 0.43 Example 5 0.64 Comparative Example 1 —— Comparative Example 2 1.53 Comparative Example 3 1.96

[0110] Table 4 Breakthrough pressure of directional water-conducting materials

[0111] Material <![CDATA[Reverse breakthrough pressure (cmH2O)]]> <![CDATA[Positive breakthrough pressure (cmH2O)]]> Example 1 10.4 0.14 Example 2 10.82 0.16 Example 3 11.06 0.16 Example 4 11.23 0.18 Example 5 11.34 0.2 Comparative Example 1 —— —— Comparative Example 2 6.32 0.16 Comparative Example 3 6.16 0.15

[0112] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for preparing a fully biodegradable anti-backflow directional water transmission composite material, characterized in that: The steps include: (1) adding a hydrophilic modifier to a plant fiber pulp with a beating degree of 18°SR to 55°SR, stirring and mixing uniformly to obtain a hydrophilic layer raw material; uniformly mixing the plant fiber pulp with a beating degree of 18°SR to 55°SR and polylactic acid to obtain a transfer layer raw material; and then using a papermaking machine to make paper in one step, wherein the upper layer of the paper sheet is the hydrophilic layer and the lower layer is the transfer layer, thereby obtaining paper; (2) The transfer layer of paper is compounded with a polylactic acid nonwoven fabric as a hydrophobic layer, and a completely biodegradable anti-backflow directional water transfer composite material is obtained by pressing.

2. The method for preparing the fully biodegradable anti-backflow directional water transmission composite material according to claim 1, characterized in that: The hydrophilic modifier described in step (1) is at least one of guar gum and carboxymethyl cellulose; The amount of the hydrophilic modifier in step (1) is 0.1 to 8% of the mass of the plant fiber pulp; The polylactic acid in step (1) is at least one of polylactic acid chopped fibers and polylactic acid particles; The mass ratio of the plant fiber pulp to the polylactic acid in step (1) is 4:6 to 9:

1.

3. The method for preparing the fully biodegradable anti-backflow directional water transmission composite material according to claim 2, characterized in that: The hydrophilic modifier described in step (1) is guar gum; The amount of the hydrophilic modifier in step (1) is 1.2 to 1.6% of the mass of the plant fiber pulp; The polylactic acid in step (1) is at least one of polylactic acid chopped fibers having an average length of 0.5 mm to 8 mm and polylactic acid particles having a particle size of 100 mesh to 1800 mesh; The mass ratio of the plant fiber pulp to the polylactic acid in step (1) is 5:5 to 7:

3.

4. The method for preparing the fully biodegradable anti-backflow directional water transmission composite material according to claim 1, characterized in that: The plant fiber pulp described in step (1) is at least one of bleached coniferous pulp, unbleached coniferous pulp, bleached broadleaf pulp, unbleached broadleaf pulp, bleached bamboo pulp and unbleached bamboo pulp; The beating degree of the plant fiber pulp described in step (1) is 28°SR~42°SR.

5. The method for preparing the fully biodegradable anti-backflow directional water transmission composite material according to claim 1, characterized in that: The hydrophilic layer in the fully biodegradable anti-backflow directional water transmission composite material described in step (2) is 20 to 120 g / m 2 The transfer layer is 10 to 120 g / m 2 The quantitative weight of polylactic acid nonwoven fabric is 15-200g / m 2 .

6. The method for preparing the fully biodegradable anti-backflow directional water transmission composite material according to claim 1, characterized in that: The conditions for the composite pressing in step (2) are: temperature 30-100° C., and line pressure 5-100 kN / m.

7. The method for preparing the fully biodegradable anti-backflow directional water transmission composite material according to claim 1, characterized in that: The stirring time in step (1) is 20 to 30 minutes; The papermaking machine described in step (1) is a double-layer fourdrinier papermaking machine or a cylinder papermaking machine.

8. A fully biodegradable anti-backflow directional water transmission composite material, characterized by: It is prepared by the method according to any one of claims 1 to 7.

9. Use of the fully biodegradable anti-backflow directional water transmission composite material according to claim 8 in the preparation of functional waterproof fabrics or clothing.

10. The use according to claim 9, characterized in that: The clothing includes underwear or quick-drying clothing for energy training.

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