A plant fiber / polylactic acid Janus membrane for directional water transport, its preparation method and application

Abstract

The present invention discloses a plant fiber / polylactic acid Janus membrane for directional water transport, its preparation method and application. The preparation method of the Janus membrane is to use the plant fiber pulp after beating and hydrophilic modification with guar gum to make paper by the traditional papermaking method, and then electrospinning is used to spray and dry the polylactic acid solution onto the paper surface. The plant fiber layer is used as the hydrophilic layer and the polylactic acid layer is used as the hydrophobic layer to obtain the plant fiber / polylactic acid Janus membrane for directional water transport. The present invention utilizes the different wetting characteristics of plant fibers and polylactic acid to generate a wetting gradient. The plant fiber layer is the hydrophilic layer and the polylactic acid layer is the hydrophobic layer, so as to realize the function of directional water transport, and it can be used in fabrics or clothes with waterproof functions.

Description

Technical Field

[0001] The present invention belongs to the field of fabric water management, and particularly relates to a plant fiber / polylactic acid Janus membrane for directional water transport, a preparation method thereof, and an application thereof. Background Art

[0002] In recent years, with the rise of the national fitness boom, consumers have paid increasing attention to the moisture absorption and sweat discharge performance of clothing textiles. Sportswear worn daily and work clothes in some specific occasions all require a certain moisture absorption and sweat discharge function. Textiles with moisture absorption and sweat discharge functions can promote the transport of liquid sweat and water vapor from the skin to the environment, thereby keeping the human body dry and cool. With the increasing demand for textiles with quick-drying properties, more and more scholars have begun to study how to improve the directional water transport performance of fabrics.

[0003] The moisture absorption and sweat discharge materials currently sold on the market mainly include polyester, polypropylene, nylon, etc., all of which are synthetic fibers and have a certain moisture absorption and sweat discharge effect. They can quickly absorb sweat from the skin, but the water transport of this kind of fabric is two-way and cannot directionally conduct the moisture on the body surface to the atmosphere. Moreover, both its water transport ability and water evaporation ability are weak, which will cause sweat to adhere to the skin of the wearer and make the wearer feel uncomfortable. Therefore, there is an urgent need to develop a material that can directionally transport water. Under the action of the wetting gradient capillary force, sweat will be transported to the environment through the tiny capillary pores of the fabric and quickly evaporated, thereby providing a good wearing experience for the wearer. Summary of the Invention

[0004] The primary object of the present invention is to overcome the deficiencies of the prior art and provide a preparation method for a plant fiber / polylactic acid Janus membrane for directional water transport.

[0005] Another object of the present invention is to provide a plant fiber / polylactic acid Janus membrane for directional water transport prepared by the above method.

[0006] Still another object of the present invention is to provide an application of the plant fiber / polylactic acid Janus membrane for directional water transport.

[0007] The object of the present invention is achieved by the following technical solutions:

[0008] A preparation method for a plant fiber / polylactic acid Janus membrane for directional water transport, which is to use the plant fiber pulp after beating and hydrophilic modification with guar gum to make paper by the traditional papermaking method, and then spray and dry a polylactic acid solution on the paper surface by electrospinning. Taking the plant fiber layer as the hydrophilic layer and the polylactic acid layer as the hydrophobic layer, the plant fiber / polylactic acid Janus membrane for directional water transport is obtained; specifically, it includes the following steps:

[0009] (1) Add the guar gum aqueous solution to the plant fiber pulp with a beating degree of 18°SR to 60°SR, stir and mix evenly, and then make paper to obtain a plant fiber layer.

[0010] (2) Add polylactic acid to a mixed solvent of ethyl acetate (EA) and N,N-dimethylformamide (DMF), stir and mix to prepare a polylactic acid electrospinning solution with a concentration of 5% to 15% by mass percentage; then spray the polylactic acid electrospinning solution onto the plant fiber layer by electrospinning to form a polylactic acid layer, and obtain a plant fiber / polylactic acid Janus membrane for directional water transport.

[0011] The concentration of the guar gum aqueous solution described in step (1) is 0.5% to 3% by mass percentage; preferably 1% to 1.5% by mass percentage.

[0012] The dosage of the guar gum aqueous solution described in step (1) accounts for 0.1% to 10% of the mass of the plant fiber pulp (bone dry); preferably 2% to 4% of the mass of the plant fiber pulp (bone dry).

[0013] The beating degree of the plant fiber pulp described in step (1) is preferably 28°SR to 42°SR.

[0014] The plant fiber pulp described in step (1) is a bleached pulp of softwood, hardwood, bamboo or other types of plant fibers, or an unbleached pulp of softwood, hardwood, bamboo or other types of plant fibers; preferably at least one of bleached softwood pulp, unbleached softwood pulp, bleached hardwood pulp, unbleached hardwood pulp, bleached bamboo pulp and unbleached bamboo pulp; more preferably at least one of bleached softwood pulp and unbleached bamboo pulp.

[0015] The stirring time described in step (1) is 15 to 30 minutes; preferably 20 minutes.

[0016] The basis weight of the plant fiber layer described in step (1) is 20 to 300 g / m 2 ; preferably 60 to 120 g / m 2 .

[0017] The mass ratio of ethyl acetate (EA) to N,N-dimethylformamide (DMF) described in step (2) is (3:7) to (7:3); preferably (5:5) to (7:3).

[0018] The molecular weight of the polylactic acid described in step (2) is 100,000 to 200,000; preferably 100,000 to 120,000.

[0019] The stirring time described in step (2) is 24 to 48 h; preferably 24 h.

[0020] In step (2), the concentration of the polylactic acid electrospinning solution is preferably 8-10% by mass.

[0021] The parameters of the electrospinning in step (2) are as follows: the diameter of the electrospinning needle is 0.67 mm, the voltage between the needle and the receiving end is 10-25 KV, the distance between the needle and the receiver is 10-30 cm, and the advancing speed of the syringe is 0.05-0.50 mL / h; preferably, the diameter of the electrospinning needle is 0.67 mm, the voltage between the needle and the receiving end is 20 KV, the distance between the needle and the receiver is 15 cm, and the advancing speed of the syringe is 0.15 mL / h.

[0022] The basis weight of the polylactic acid layer described in step (2) is 1-10 g / m 2 ; preferably 2-7 g / m 2 .

[0023] A plant fiber / polylactic acid Janus membrane for directional water transport is prepared by the method described in any one of the above.

[0024] Application of the completely biodegradable anti-backflow directional water transport composite material in the preparation of a fabric (waterproof fabric) or clothing (clothes) with a waterproof function.

[0025] The clothing with a waterproof function described above includes close-fitting clothing, sports quick-drying clothing, etc.

[0026] The present invention has the following advantages and effects compared with the prior art:

[0027] 1. The polylactic acid (PLA) in the present invention has a wide source. It is a polymer with lactic acid as the raw material and does not rely on fossil raw materials such as petroleum, and has good biocompatibility; the plant fiber is a natural material. Because it contains a large number of hydrogen bonds, it has strong water absorption, while the water absorption of PLA is relatively weak; by using the different wetting characteristics of plant fiber and polylactic acid to generate a wetting gradient, the plant fiber layer is a hydrophilic layer and the polylactic acid layer is a hydrophobic layer, so as to achieve the function of directional water transport. Using this material to make clothing can avoid sweat sticking to the body and improve the comfort of the material.

[0028] 2. The raw materials and auxiliary materials used in the present invention have completely biodegradable properties, and the prepared directional water transport material has environmental protection, skin-friendly and completely biodegradable properties.

[0029] 3. The present invention uses electrospinning to compound the polylactic acid and the plant fiber layer substrate, and can obtain the optimal pore size of the polylactic acid electrospinning membrane and the diameter of the polylactic acid fiber, so as to achieve the best directional water transport effect. Description of the Drawings

[0030] Figure 1 It is the original data graph of the unidirectional transport index test of the plant fiber / polylactic acid Janus membrane prepared in Example 3.

[0031] Figure 2 It is a physical picture of the plant fiber / polylactic acid Janus membrane prepared in Example 3. Detailed implementation manners

[0032] The present invention will be further described in detail below in conjunction with embodiments, but the implementation manners 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 technical field. The test methods in the following embodiments that do not specify specific experimental conditions usually follow conventional experimental conditions or the experimental conditions recommended by the manufacturer. 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 Shitou brand, purchased from SMURFIT-STONE Contanier Co., Ltd.; the unbleached bamboo pulp is purchased from Sichuan Yongfeng Paper Co., Ltd.

[0034] The polylactic acid particles involved in the examples and comparative examples of the present invention have a particle size of 100 mesh to 1800 mesh and a weight average molecular weight of 100,000 to 150,000, and are purchased from Zhejiang Haining Saiyoupu Chemical Technology Co., Ltd.; the polyurethane is purchased from Shenzhen Yitian Chemical Co., Ltd.

[0035] Example 1

[0036] A preparation method of a plant fiber / polylactic acid Janus membrane for directional water transport, comprising the following steps:

[0037] (1) Beating the bleached softwood pulp to 28°SR, and reserving it for later use.

[0038] (2) Diluting guar gum with deionized water into an aqueous solution with a concentration of 1% by mass percentage, and reserving it for later use.

[0039] (3) Using a compound solvent of ethyl acetate (EA) and N,N-dimethylformamide (DMF) (EA:DMF = 5:5, mass ratio) as the solvent and polylactic acid powder with a molecular weight of 100,000 as the solute, magnetically stirring at room temperature for 24 h to prepare a polylactic acid electrospinning solution with a mass fraction of 8%, and reserving it for later use.

[0040] (4) 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), with a dosage of 2.0 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 obtain a raw material, and reserving it for later use.

[0041] (5) Use a paper machine to form the raw materials prepared in step (4) into paper with a basis weight of 60 g / m 2 , obtaining a plant fiber layer for standby.

[0042] (6) Use the plant fiber layer obtained in step (5) as the substrate, and spray the polylactic acid electrospinning solution in step (3) onto it by electrospinning (the diameter of the electrospinning needle is 0.67 mm, the voltage between the needle and the receiving end is 20 KV, the distance between the needle and the receiver is 15 cm, and the advancing speed of the syringe is 0.15 mL / h). The basis weight of the polylactic acid layer is 2 g / m 2 , obtaining the plant fiber / polylactic acid Janus membrane for directional water transport.

[0043] Example 2

[0044] A preparation method of a plant fiber / polylactic acid Janus membrane for directional water transport, comprising the following steps:

[0045] (1) Beat bleached softwood pulp to 32°SR for standby.

[0046] (2) Dilute guar gum with deionized water into an aqueous solution with a concentration of 1.2% by mass for standby.

[0047] (3) Use a compound solvent of ethyl acetate (EA) and N,N-dimethylformamide (DMF) (EA:DMF = 6:4, mass ratio) as the solvent, and polylactic acid powder with a molecular weight of 120,000 as the solute. Stir magnetically at room temperature for 24 h to prepare a 9% polylactic acid electrospinning solution for standby.

[0048] (4) Add the guar gum solution prepared in step (2) to the bleached softwood pulp with a beating degree of 32°SR prepared in step (1), with a dosage of 2.5 wt% (the absolute dry mass ratio of guar gum to bleached softwood pulp with a beating degree of 32°SR), and stir for 20 minutes as the raw material for standby.

[0049] (5) Use a paper machine to form the raw materials prepared in step (4) into paper with a basis weight of 90 g / m 2 , obtaining a plant fiber layer for standby.

[0050] (6) Use the plant fiber layer obtained in step (5) as the substrate, and spray the polylactic acid electrospinning solution in step (3) onto it by electrospinning (the diameter of the electrospinning needle is 0.67 mm, the voltage between the needle and the receiving end is 20 KV, the distance between the needle and the receiver is 15 cm, and the advancing speed of the syringe is 0.15 mL / h)), and the basis weight of the polylactic acid layer is 5 g / m 2, the plant fiber / polylactic acid Janus membrane for directional water transport is obtained.

[0051] Example 3

[0052] A preparation method of a plant fiber / polylactic acid Janus membrane for directional water transport includes the following steps:

[0053] (1) Beat bleached softwood pulp to 38°SR and set aside.

[0054] (2) Dilute guar gum with deionized water into an aqueous solution with a concentration of 1.4% by mass and set aside.

[0055] (3) Use a compound solvent of ethyl acetate (EA) and N,N-dimethylformamide (DMF) (EA:DMF = 7:3, mass ratio) as the solvent, and polylactic acid powder with a molecular weight of 120,000 as the solute. Stir magnetically at room temperature for 24 h to prepare a 10% polylactic acid electrospinning solution and set aside.

[0056] (4) Add the guar gum solution prepared in step (2) to the bleached softwood pulp with a beating degree of 38°SR prepared in step (1), with a dosage of 3.0 wt% (the absolute dry mass ratio of guar gum to bleached softwood pulp with a beating degree of 38°SR), and stir for 20 minutes as the raw material and set aside.

[0057] (5) Use a paper machine to form the raw material prepared in step (4) into paper with a basis weight of 100 g / m 2 to obtain a plant fiber layer and set aside.

[0058] (6) Use the plant fiber layer obtained in step (5) as the substrate, and spray the polylactic acid electrospinning solution in step (3) on it by electrospinning (the electrospinning needle diameter is 0.67 mm, the voltage between the needle and the receiving end is 20 KV, the distance between the needle and the receiver is 15 cm, and the injection speed of the syringe is 0.15 mL / h)), and the basis weight of the polylactic acid layer is 7 g / m 2 to obtain the plant fiber / polylactic acid Janus membrane for directional water transport ( Figure 2 ).

[0059] Example 4

[0060] A preparation method of a plant fiber / polylactic acid Janus membrane for directional water transport includes the following steps:

[0061] (1) Beat unbleached bamboo pulp to 42°SR and set aside.

[0062] (2) Dilute guar gum with deionized water into an aqueous solution with a concentration of 1.5% by mass and set aside.

[0063] (3) The compound solvent used is a mixed solvent of ethyl acetate (EA) and N,N-dimethylformamide (DMF) (EA:DMF = 7:3, mass ratio), and the solute is polylactic acid powder with a molecular weight of 120,000. Stir magnetically at room temperature for 24 h to prepare a polylactic acid electrospinning solution with a mass fraction of 10%, and set aside for use.

[0064] (4) Add the guar gum solution prepared in step (2) to the unbleached bamboo pulp with a beating degree of 42°SR prepared in step (1), with a dosage of 4.0 wt% (the absolute dry mass ratio of guar gum to unbleached bamboo pulp with a beating degree of 42°SR), and stir for 20 minutes to obtain the raw material, which is set aside for use.

[0065] (5) Use a paper machine to make paper from the raw material prepared in step (4), with a basis weight of 120 g / m 2 , to obtain a plant fiber layer, which is set aside for use.

[0066] (6) Use the plant fiber layer obtained in step (5) as the substrate, and spray the polylactic acid electrospinning solution in step (3) on it by electrospinning (the diameter of the electrospinning needle is 0.67 mm, the voltage between the needle and the receiving end is 20 KV, the distance between the needle and the receiver is 15 cm, and the advancing speed of the syringe is 0.15 mL / h). The basis weight of the polylactic acid layer is 6 g / m 2 , to obtain the plant fiber / polylactic acid Janus membrane for directional water transport.

[0067] Comparative Example 1

[0068] A method for preparing a single-layer plant fiber membrane, comprising the following steps:

[0069] (1) Beat the bleached softwood pulp to 28°SR, and set aside for use.

[0070] (2) Dilute guar gum with deionized water to an aqueous solution with a concentration of 1% by mass, and set aside for use.

[0071] (3) Add the guar gum solution prepared in step (2) to the bleached softwood pulp with a beating degree of 28°SR prepared in step (1), with a dosage of 2.0 wt% (the absolute dry mass ratio of guar gum to bleached softwood pulp with a beating degree of 28°SR), and stir for 20 minutes to obtain the raw material, which is set aside for use.

[0072] (4) Use a paper machine to make paper from the raw material prepared in step (3), with a basis weight of 62 g / m 2 , to obtain a plant fiber layer, which is set aside for use.

[0073] Comparative Example 2

[0074] A preparation method of a plant fiber / polyurethane Janus membrane for directional water transport, comprising the following steps:

[0075] (1) Beat bleached softwood pulp to 28°SR and set aside.

[0076] (2) Dilute guar gum with deionized water into an aqueous solution with a concentration of 1% by mass percentage and set aside.

[0077] (3) Use a compound solvent of ethyl acetate (EA) and N,N-dimethylformamide (DMF) (EA:DMF = 5:5, mass ratio) as the solvent, and polyurethane powder with a molecular weight of 100,000 as the solute. Stir magnetically at room temperature for 24 h to prepare a polyurethane electrospinning solution with a mass fraction of 8%, and set aside.

[0078] (4) Add the guar gum solution prepared in step (2) to the bleached softwood pulp with a beating degree of 28°SR prepared in step (1), with a dosage of 2.0 wt% (the absolute dry mass ratio of guar gum to "bleached softwood pulp with a beating degree of 28°SR"), and stir for 20 minutes as the raw material and set aside.

[0079] (5) Use a paper machine to form the raw material prepared in step (4) into paper with a basis weight of 60 g / m 2 to obtain a plant fiber layer and set aside.

[0080] (6) Use the plant fiber layer obtained in step (5) as the substrate, and spray the polyurethane electrospinning solution in step (3) on it by electrospinning (the diameter of the electrospinning needle is 0.67 mm, the voltage between the needle and the receiving end is 20 KV, the distance between the needle and the receiver is 15 cm, and the pushing speed of the syringe is 0.15 mL / h). The basis weight of the polyurethane layer is 2 g / m 2 to obtain the plant fiber / polylactic acid Janus membrane for directional water transport.

[0081] Comparative Example 3

[0082] A preparation method of a plant fiber / polyurethane Janus membrane for directional water transport, comprising the following steps:

[0083] (1) Beat bleached softwood pulp to 32°SR and set aside.

[0084] (2) Dilute guar gum with deionized water into an aqueous solution with a concentration of 1.2% by mass percentage and set aside.

[0085] (3) A composite solvent of ethyl acetate (EA) and N,N-dimethylformamide (DMF) (EA:DMF = 6:4, mass ratio) was used, and the solute was polyurethane powder with a molecular weight of 120,000. It was magnetically stirred at room temperature for 24 h to prepare a polyurethane electrospinning solution with a mass fraction of 9%, and stored for later use.

[0086] (4) The guar gum solution prepared in step (2) was added to the bleached softwood pulp with a beating degree of 28°SR prepared in step (1), and the dosage was 2.5 wt% (the absolute dry mass ratio of guar gum to "bleached softwood pulp with a beating degree of 28°SR"), and stirred for 20 minutes to obtain the raw material, which was stored for later use.

[0087] (5) The raw material prepared in step (4) was made into paper by a paper machine, and the basis weight was 60 g / m 2 , to obtain a plant fiber layer, which was stored for later use.

[0088] (6) Using the plant fiber layer obtained in step (5) as the substrate, the polyurethane electrospinning solution in step (3) was sprayed on it by electrospinning (the diameter of the electrospinning needle was 0.67 mm, the voltage between the needle and the receiving end was 20 KV, the distance between the needle and the receiver was 15 cm, and the advancing speed of the syringe was 0.15 mL / h). The basis weight of the polyurethane layer was 5 g / m 2 , to obtain the plant fiber / polylactic acid Janus membrane for directional water transport.

[0089] Comparative Example 4

[0090] A preparation method of a plant fiber / polylactic acid Janus membrane for directional water transport, comprising the following steps:

[0091] (1) Unbleached bamboo pulp was beaten to 42°SR and stored for later use.

[0092] (2) Guar gum was diluted with deionized water into an aqueous solution with a concentration of 1.5% by mass, and stored for later use.

[0093] (3) A composite solvent of ethyl acetate (EA) and N,N-dimethylformamide (DMF) (EA:DMF = 7:3, mass ratio) was used, and the solute was polylactic acid powder with a molecular weight of 120,000. It was magnetically stirred at room temperature for 24 h to prepare a polylactic acid electrospinning solution with a mass fraction of 10%, and stored for later use.

[0094] (4) The guar gum solution prepared in step (2) was added to the unbleached bamboo pulp with a beating degree of 42°SR prepared in step (1), and the dosage was 4.0 wt% (the absolute dry mass ratio of guar gum to unbleached bamboo pulp with a beating degree of 42°SR), and stirred for 20 minutes to obtain the raw material, which was stored for later use.

[0095] (5) Use a paper machine to form the raw materials prepared in step (4) into paper with a basis weight of 120 g / m 2 , obtaining a plant fiber layer for standby.

[0096] (6) Take the plant fiber layer obtained in step (5) as the substrate, and use the electrospinning method to spray the polylactic acid electrospinning solution in step (3) thereon (the diameter of the electrospinning needle is 0.67 mm, the voltage between the needle and the receiving end is 35 KV, the distance between the needle and the receiver is 15 cm, and the pushing speed of the syringe is 0.15 mL / h). The basis weight of the polylactic acid layer is 6 g / m 2 , obtaining the plant fiber / polylactic acid Janus membrane for directional water transport.

[0097] Comparative Example 5

[0098] A preparation method of a plant fiber / polylactic acid Janus membrane for directional water transport, comprising the following steps:

[0099] (1) Beat unbleached bamboo pulp to 42° SR for standby.

[0100] (2) Dilute guar gum with deionized water into an aqueous solution with a concentration of 1.5% by mass for standby.

[0101] (3) Use a compound solvent of ethyl acetate (EA) and N,N-dimethylformamide (DMF) (EA:DMF = 7:3, mass ratio) as the solvent, and polylactic acid powder with a molecular weight of 120,000 as the solute. Stir magnetically at room temperature for 24 h to prepare a 10% by mass polylactic acid electrospinning solution for standby.

[0102] (4) Add the guar gum solution prepared in step (2) to the unbleached bamboo pulp with a beating degree of 42° SR prepared in step (1) in an amount of 4.0 wt% (the absolute dry mass ratio of guar gum to unbleached bamboo pulp with a beating degree of 42° SR), and stir for 20 minutes as the raw material for standby.

[0103] (5) Use a paper machine to form the raw materials prepared in step (4) into paper with a basis weight of 120 g / m 2 , obtaining a plant fiber layer for standby.

[0104] (6) Take the plant fiber layer obtained in step (5) as the substrate, and use the electrospinning method to spray the polylactic acid electrospinning solution in step (3) thereon (the diameter of the electrospinning needle is 0.67 mm, the voltage between the needle and the receiving end is 15 KV, the distance between the needle and the receiver is 35 cm, and the pushing speed of the syringe is 0.15 mL / h). The basis weight of the polylactic acid layer is 6 g / m 2, the plant fiber / polylactic acid Janus membrane for directional water transport is obtained.

[0105] Comparative Example 6

[0106] A preparation method of a plant fiber / polylactic acid Janus membrane for directional water transport, comprising the following steps:

[0107] (1) Beat unbleached bamboo pulp to 42°SR and set aside.

[0108] (2) Dilute guar gum with deionized water into an aqueous solution with a concentration of 1.5% by mass and set aside.

[0109] (3) Use a compound solvent of ethyl acetate (EA) and N,N-dimethylformamide (DMF) (EA:DMF = 7:3, mass ratio) as the solvent, and polylactic acid powder with a molecular weight of 120,000 as the solute. Stir magnetically at room temperature for 24 h to prepare a 10% by mass polylactic acid electrospinning solution and set aside.

[0110] (4) Add the guar gum solution prepared in step (2) to the unbleached bamboo pulp with a beating degree of 42°SR prepared in step (1), with a dosage of 4.0 wt% (the absolute dry mass ratio of guar gum to unbleached bamboo pulp with a beating degree of 42°SR), and stir for 20 minutes as the raw material and set aside.

[0111] (5) Use a paper machine to form the raw material prepared in step (4) into paper with a basis weight of 120 g / m 2 , to obtain a plant fiber layer and set aside.

[0112] (6) Use the plant fiber layer obtained in step (5) as the substrate, and spray the polylactic acid electrospinning solution in step (3) on it by electrospinning (the electrospinning needle diameter is 0.67 mm, the voltage between the needle and the receiving end is 15 KV, the distance between the needle and the receiver is 15 cm, and the advancing speed of the syringe is 0.55 mL / h). The basis weight of the polylactic acid layer is 6 g / m 2 , to obtain the plant fiber / polylactic acid Janus membrane for directional water transport.

[0113] Comparative Example 7

[0114] A preparation method of a plant fiber / polylactic acid Janus membrane for directional water transport, comprising the following steps:

[0115] (1) Beat unbleached bamboo pulp to 42°SR and set aside.

[0116] (2) Dilute guar gum with deionized water into an aqueous solution with a concentration of 1.5% by mass and set aside.

[0117] (3) A composite solvent of ethyl acetate (EA) and N,N-dimethylformamide (DMF) (EA:DMF = 7:3, mass ratio) was used, and the solute was polylactic acid powder with a molecular weight of 60,000. It was magnetically stirred at room temperature for 24 h to prepare a 10% (mass fraction) polylactic acid electrospinning solution for standby.

[0118] (4) The guar gum solution prepared in step (2) was added to the unbleached bamboo pulp with a beating degree of 42°SR prepared in step (1), and the dosage was 4.0 wt% (the absolute dry mass ratio of guar gum to unbleached bamboo pulp with a beating degree of 42°SR), and it was stirred for 20 minutes as the raw material for standby.

[0119] (5) The raw material prepared in step (4) was made into paper by a paper machine with a basis weight of 120 g / m 2 , obtaining a plant fiber layer for standby.

[0120] (6) Using the plant fiber layer obtained in step (5) as the substrate, the polylactic acid electrospinning solution in step (3) was sprayed on it by electrospinning (the diameter of the electrospinning needle was 0.67 mm, the voltage between the needle and the receiving end was 20 KV, the distance between the needle and the receiver was 15 cm, and the pushing speed of the syringe was 0.15 mL / h). The basis weight of the polylactic acid layer was 6 g / m 2 , obtaining the plant fiber / polylactic acid Janus membrane for directional water transport.

[0121] Comparative Example 8

[0122] A preparation method of a plant fiber / polylactic acid Janus membrane for directional water transport, comprising the following steps:

[0123] (1) The unbleached bamboo pulp was beaten to 42°SR for standby.

[0124] (2) Guar gum was diluted with deionized water into an aqueous solution with a concentration of 1.5% (mass percentage) for standby.

[0125] (3) A composite solvent of ethyl acetate (EA) and N,N-dimethylformamide (DMF) (EA:DMF = 7:3, mass ratio) was used, and the solute was polylactic acid powder with a molecular weight of 60,000. It was magnetically stirred at room temperature for 24 h to prepare a 20% (mass fraction) polylactic acid electrospinning solution for standby.

[0126] (4) The guar gum solution prepared in step (2) was added to the unbleached bamboo pulp with a beating degree of 42°SR prepared in step (1), and the dosage was 4.0 wt% (the absolute dry mass ratio of guar gum to unbleached bamboo pulp with a beating degree of 42°SR), and it was stirred for 20 minutes as the raw material for standby.

[0127] (5) Use a paper machine to form the raw materials prepared in step (4) into paper with a basis weight of 120 g / m 2 , obtaining a plant fiber layer for standby.

[0128] (6) Use the plant fiber layer obtained in step (5) as the substrate, and spray the polylactic acid electrospinning solution in step (3) onto it by electrospinning (the electrospinning needle diameter is 0.67 mm, the voltage between the needle and the receiving end is 20 KV, the distance between the needle and the receiver is 15 cm, and the injection speed of the syringe is 0.15 mL / h). The basis weight of the polylactic acid layer is 6 g / m 2 , obtaining the plant fiber / polylactic acid Janus membrane for directional water transport.

[0129] Comparative Example 9

[0130] A preparation method of a plant fiber / polylactic acid Janus membrane for directional water transport, comprising the following steps:

[0131] (1) Beat unbleached bamboo pulp to 42° SR for standby.

[0132] (2) Dilute guar gum with deionized water into an aqueous solution with a concentration of 1.5% by mass for standby.

[0133] (3) Use a compound solvent of ethyl acetate (EA) and N,N-dimethylformamide (DMF) (EA:DMF = 7:3, mass ratio) as the solvent, and polylactic acid powder with a molecular weight of 120,000 as the solute. Stir magnetically at room temperature for 24 h to prepare a 10% polylactic acid electrospinning solution for standby.

[0134] (4) Add the guar gum solution prepared in step (2) to the unbleached bamboo pulp with a beating degree of 42° SR prepared in step (1), with a dosage of 4.0 wt% (the absolute dry mass ratio of guar gum to unbleached bamboo pulp with a beating degree of 42° SR), and stir for 20 minutes as the raw material for standby.

[0135] (5) Use a paper machine to form the raw materials prepared in step (4) into paper with a basis weight of 120 g / m 2 , obtaining a plant fiber layer for standby.

[0136] (6) Use the plant fiber layer obtained in step (5) as the substrate, and spray the polylactic acid electrospinning solution in step (3) onto it by electrospinning (the electrospinning needle diameter is 0.67 mm, the voltage between the needle and the receiving end is 20 KV, the distance between the needle and the receiver is 15 cm, and the injection speed of the syringe is 0.15 mL / h). The basis weight of the polylactic acid layer is 15 g / m 2, the plant fiber / polylactic acid Janus membrane for directional water transport is obtained.

[0137] Comparative Example 10

[0138] A preparation method of a plant fiber / polylactic acid Janus membrane for directional water transport includes the following steps:

[0139] (1) Beat unbleached bamboo pulp to 42°SR and set aside.

[0140] (2) Dilute guar gum with deionized water into an aqueous solution with a concentration of 1.5% by mass and set aside.

[0141] (3) Use a compound solvent of ethyl acetate (EA) and N,N-dimethylformamide (DMF) (EA:DMF = 7:3, mass ratio) as the solvent and polylactic acid powder with a molecular weight of 120,000 as the solute. Stir magnetically at room temperature for 24 h to prepare a 10% polylactic acid electrospinning solution and set aside.

[0142] (4) Add the guar gum solution prepared in step (2) to the unbleached bamboo pulp with a beating degree of 42°SR prepared in step (1), with a dosage of 4.0 wt% (the absolute dry mass ratio of guar gum to unbleached bamboo pulp with a beating degree of 42°SR), and stir for 20 minutes as the raw material and set aside.

[0143] (5) Use a paper machine to form the raw material prepared in step (4) into paper with a basis weight of 120 g / m 2 to obtain a plant fiber layer and set aside.

[0144] (6) Use the plant fiber layer obtained in step (5) as the substrate, and spray the polylactic acid electrospinning solution in step (3) on it by electrospinning (the electrospinning needle diameter is 0.67 mm, the voltage between the needle and the receiving end is 20 KV, the distance between the needle and the receiver is 15 cm, and the pushing speed of the syringe is 0.15 mL / h). The basis weight of the polylactic acid layer is 0.5 g / m 2 to obtain the plant fiber / polylactic acid Janus membrane for directional water transport.

[0145] Effect Example

[0146] Test the water transport time, the wettability difference between the two sides after water transport, and the unidirectional transport index of the plant fiber / polylactic acid Janus membranes prepared in Test Examples 1-4, the plant fiber single-layer membrane prepared in Comparative Example 1, and the plant fiber / polyurethane Janus membranes prepared in Comparative Examples 2-3; among them,

[0147] ① The method for testing the water transport time is as follows: Use an optical contact angle / surface tension measuring instrument to measure the water transport time. Start timing from the moment the water droplet touches the Janus membrane and end when the water contact angle is 0°. Repeat three times.

[0148] ② The method for testing the wettability difference between the two sides after water transport is as follows: Completely wet a piece of filter paper and place it on the hydrophobic layer of the prepared Janus membrane. Press it for 10 s under a pressure of 10 Mpa to make the hydrophobic side of the Janus membrane evenly wetted. Then take out the filter paper and use a surface humidity measuring instrument to measure the surface humidity of both sides of the Janus membrane. Repeat three times.

[0149] ③ The unidirectional transport index is tested in accordance with GB / T 21655.2 "Assessment Method for Moisture Absorption and Quick Drying Property of Textiles - Part 2: Dynamic Moisture Transfer Method".

[0150] The directional water transport time is shown in Table 1; there is an obvious humidity difference on both sides after directional transport, and the effect is shown in Table 2; the unidirectional transport index is an important indicator to measure the unidirectional water conduction ability of the material, and its unidirectional transport index is shown in Table 3 below. The original test data of the unidirectional transport index of the plant fiber / polylactic acid Janus membrane prepared in Example 3 are as Figure 1 shown. It can be seen from the results that: The Janus membranes prepared in Examples 1 - 4 can all make water rapidly transfer from the hydrophobic side to the hydrophilic side directionally and keep the hydrophobic side relatively dry after testing, indicating that the directional water transport materials prepared in Examples 1 - 4 all have good water transport functions. However, the pure plant fiber material in Comparative Example 1 has no directional water conduction function and cannot test the unidirectional water conduction performance of the material. And the pure polylactic acid material also has no directional water conduction function and cannot test the unidirectional water conduction performance of the material. Therefore, no separate control is set here. In addition, compared with the plant fiber / polyurethane Janus membranes in Comparative Examples 2 and 3, the plant fiber / polylactic acid Janus membrane prepared in the present invention has better water transport functions.

[0151] In addition, from the results of Example 4 and Comparative Examples 4 to 10, it can be seen that the voltage between the needle and the receiving end (Comparative Example 4), the distance between the needle and the receiver (Comparative Example 5), the advancing speed of the syringe (Comparative Example 6), the molecular weight of the polylactic acid powder (Comparative Examples 7 and 8), the concentration of the polylactic acid electrospinning solution (Comparative Example 8), and the basis weight of the polylactic acid layer (Comparative Examples 9 and 10) in the electrospinning process all affect the water transport function of the plant fiber / polylactic acid Janus membrane. The electrospinning solvent process used in the present invention can bring unique properties, and changing the molecular weight of polylactic acid and the concentration of the spinning solvent cannot achieve the effects of the present invention. The basis weight of the polylactic acid electrospinning layer in the present invention has a great influence on the directional water transport performance of the composite material. If the basis weight of polylactic acid is too low, the thickness of the polylactic acid layer is too low, and it is impossible to generate a good wetting gradient; if the basis weight of the polylactic acid layer is too high, the porosity decreases, and the polylactic acid layer is too thick, and it is also impossible to generate a wetting gradient.

[0152] Therefore, for the Janus membrane prepared by the method of the present invention, since the plant fiber contains a large number of hydrogen bonds, it can quickly adsorb a large amount of water molecules and has good water absorption. The water absorption of PLA is relatively weak. By utilizing the different wetting properties of the plant fiber and polylactic acid to generate a wetting gradient, the plant fiber layer is a hydrophilic layer and the polylactic acid layer is a hydrophobic layer, thereby realizing the directional water transport function. Water quickly transports from the polylactic acid side to the plant fiber side, and less water remains on the polylactic acid side. The plant fiber / polylactic acid directional water transport membrane can well complete the directional water conduction, enabling water to quickly conduct from the wearer's body surface to the environment. Sweat will not adhere to the wearer's body surface, keeping it dry and improving the comfort of the clothing. That is to say, the directional water transport membrane prepared in the present invention can provide comfort for the wearer in hot or humid environments, and the raw materials and auxiliary materials used in the present invention have completely biodegradable properties, and the prepared directional water transport material has completely biodegradable properties.

[0153] Table 1 Water transport time of the directional water transport material

[0154] Material Moisture transmission time / s Example 1 2.122 Example 2 1.886 Example 3 1.578 Example 4 1.201 Comparative Example 1 —— Comparative Example 2 4.328 Comparative Example 3 5.673 Comparative Example 4 6.398 Comparative Example 5 5.193 Comparative Example 6 5.352 Comparative Example 7 6.840 Comparative Example 8 5.743 Comparative Example 9 10.961 Comparative Example 10 ——

[0155] Table 2 Wettability difference between the two sides of the directional water transport material after water transport

[0156]

[0157]

[0158] Table 3 Unidirectional transfer index of the directional water conduction material

[0159]

[0160]

[0161] The above embodiments are preferred embodiments of the present invention. However, the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A preparation method of a plant fiber / polylactic acid Janus membrane for directional water transport, characterized in that, Specifically, it includes the following steps: (1) Add the guar gum aqueous solution to the plant fiber pulp with a beating degree of 18°SR to 60°SR, stir and mix evenly, and then make paper to obtain a plant fiber layer; (2) Add polylactic acid to the mixed solvent of ethyl acetate and N,N-dimethylformamide, stir and mix to prepare a polylactic acid electrospinning solution with a concentration of 8% to 10% by mass percentage; then spray the polylactic acid electrospinning solution onto the plant fiber layer by electrospinning to form a polylactic acid layer, and obtain a plant fiber / polylactic acid Janus membrane for directional water transport; In step (2), the weight-average molecular weight of the polylactic acid is 100,000 to 200,000; In step (2), the mass ratio of ethyl acetate to N,N-dimethylformamide is 3:7 to 7:3; The parameters of the electrospinning in step (2) are: the diameter of the electrospinning needle is 0.67 mm, the voltage between the needle and the receiving end is 10 to 25 KV, the distance between the needle and the receiver is 10 to 30 cm, and the advancing speed of the syringe is 0.05 to 0.50 mL / h; The quantification of the polylactic acid layer described in step (2) is 1 to 10 g / m 2 .

2. The method for preparing a plant fiber / polylactic acid Janus membrane for directional water transport according to claim 1, wherein: The basis weight of the plant fiber layer described in step (1) is 20 to 300 g / m 2 .

3. The method for preparing a plant fiber / polylactic acid Janus membrane for directional water transport according to claim 2, wherein: The basis weight of the plant fiber layer described in step (1) is 60 to 120 g / m 2 ; The quantification of the polylactic acid layer described in step (2) is 2 to 7 g / m 2 .

4. The method for preparing a plant fiber / polylactic acid Janus membrane for directional water transport according to claim 1, wherein: In step (1), the concentration of the guar gum aqueous solution is 0.5% to 3% by mass percentage; In step (1), the dosage of the guar gum aqueous solution accounts for 0.1% to 10% of the mass of the plant fiber pulp.

5. The method for preparing a plant fiber / polylactic acid Janus membrane for directional water transport according to claim 4, wherein: In step (1), the concentration of the guar gum aqueous solution is 1% to 1.5% by mass percentage; In step (1), the dosage of the guar gum aqueous solution accounts for 2% to 4% of the mass of the plant fiber pulp.

6. The method for preparing a plant fiber / polylactic acid Janus membrane for directional water transport according to claim 1, wherein: In step (1), the beating degree of the plant fiber pulp is 28°SR to 42°SR; In step (1), the plant fiber pulp is at least one of bleached softwood pulp, unbleached softwood pulp, bleached hardwood pulp, unbleached hardwood pulp, bleached bamboo pulp and unbleached bamboo pulp.

7. The method for preparing a plant fiber / polylactic acid Janus membrane for directional water transport according to claim 1, wherein: In step (1), the stirring time is 15 to 30 minutes; In step (2), the stirring time is 24 to 48 h.

8. A plant fiber / polylactic acid Janus membrane for directional water transport, characterized in that: Prepared by the method according to any one of claims 1 to 7.

9. Application of the plant fiber / polylactic acid Janus membrane for directional water transport according to claim 8 in the preparation of a fabric or clothing with a waterproof function.

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