An antibacterial PLA-based Janus film, a preparation method and a cloth diaper based on the PLA-based Janus film

Abstract

The application discloses an antibacterial PLA-based Janus film, a preparation method and a cloth diaper based on the PLA-based Janus film. The prepared Janus film has excellent single-side hydrophobicity, one-way liquid moisture conductivity and antibacterial performance. Based on the special functions, a cloth diaper with an antibacterial PLA-based Janus film as an inner surface layer is prepared. The cloth diaper is constructed by replacing an inner surface layer of a commercial cloth diaper with the prepared antibacterial PLA-based Janus film, so as to solve the problems of poor hydrophobicity and moisture conductivity of the inner surface layer of the existing cloth diaper and weak antibacterial performance.

Description

Technical Field

[0001] This invention relates to the preparation and application research of functional materials, specifically to an antibacterial PLA-based Janus membrane, its preparation method, and cloth diapers based on the PLA-based Janus membrane. Its liquid unidirectional conductivity and antibacterial properties were investigated, and it was applied to the inner surface of cloth diapers, solving the shortcomings of existing cloth diaper inner surface layers such as poor hydrophobicity and moisture wicking properties, and weak antibacterial properties. Background Technology

[0002] Diapers, as common absorbent hygiene products, are widely used in the care of infants and the elderly. Diaper products include disposable absorbent cores / pads / paper diapers and reusable cloth diapers. Among them, disposable cloth diapers (paper diapers) are currently the largest-selling product due to their high performance and convenience. However, disposable diapers are mostly made of petroleum-based plastics and absorbent polymers, mainly including PP, PE, viscose, synthetic rubber, and superabsorbent polymers (SAP, mainly sodium polyacrylate). These materials are difficult to spontaneously degrade in the environment, so the disposal of large quantities of discarded paper diapers puts enormous pressure on energy and the environment. Cloth diapers are made of renewable materials such as cotton, bamboo, or hemp fibers and are reusable. However, the inner layer of existing cloth diapers is mostly composed of yarn, which has poor hydrophobicity and moisture-wicking properties and lacks effective antibacterial properties, resulting in poor comfort and convenience, and causing cloth diaper products to have a small market share. As more and more countries recognize the problem of the depletion of non-renewable resources and the negative environmental impact of disposable diaper waste, the research and development of reusable high-performance cloth diaper products is of great significance. Summary of the Invention

[0003] Cloth diapers mainly consist of three parts: a one-way moisture-wicking inner layer; a multi-layered highly absorbent core for storing urine; and an outer layer to prevent urine leakage. Addressing the problems of poor hydrophobicity and moisture wicking properties, and weak antibacterial performance of the inner surface of existing cloth diapers, leading to poor comfort and convenience, this invention designs and prepares a silver-loaded PLA-based Janus membrane based on biodegradable and environmentally friendly polylactic acid (PLA). This Janus membrane possesses excellent one-sided hydrophobicity, one-way liquid moisture wicking, and antibacterial properties. Replacing the yarn inner surface of existing cloth diapers with this membrane results in a high-performance cloth diaper. The silver on the surface of the silver-loaded PLA-based Janus membrane and the hydrophobic polydimethylsiloxane (PDMS) are bio-friendly and can come into direct contact with the human body without causing any harm to human skin.

[0004] The present invention adopts the following technical solution:

[0005] A method for preparing an antibacterial silver-supported PLA-based Janus membrane, the method comprising the following steps:

[0006] Step 1: Prepare dopamine-loaded PLA membrane

[0007] PLA fiber membrane (filament diameter 1~10 μm, pore size 1~20 μm) was placed in a dopamine solution and stirred. The PLA fiber membrane was then removed from the dopamine solution and washed to obtain a dopamine-loaded PLA membrane.

[0008] Step 2, Preparation of silver-supported PLA film

[0009] The dopamine-loaded PLA membrane prepared in step 1 was placed in silver nitrate solution and allowed to stand in a water bath.

[0010] The PLA membrane was removed from the silver nitrate solution, ultrasonically treated, washed, and dried. The purpose of ultrasonic treatment was to remove excess silver particles from the loose surface structure, thereby obtaining a stable silver-loaded PLA membrane.

[0011] Step 3, Preparation of silver-supported PLA-based Janus film

[0012] Dimethylsiloxane and a curing agent are dissolved in an organic solvent to obtain a dimethylsiloxane solution;

[0013] After pre-wetting the silver-loaded PLA membrane prepared in step 2 with water, lay it flat, spray the dimethylsiloxane solution onto one side of the silver-loaded PLA membrane, dry it, and take it out to obtain a silver-loaded PLA-based Janus membrane with one side hydrophilic and the other side hydrophobic.

[0014] Further, in step 1, the dopamine solution is prepared by the following method: weighing dopamine and dissolving it in Tris-HCl buffer solution using mechanical stirring to prepare a dopamine solution, wherein the ratio of dopamine to buffer solution is 0.25g~0.3g:100mL, and the pH of the buffer solution is 8~9.

[0015] Further, in step 1, the PLA fiber membrane is placed in a dopamine solution and magnetically stirred at 30~35℃ for 40~48h. Then, the PLA fiber membrane is removed from the dopamine solution and rinsed with deionized water 4~5 times to obtain a dopamine-loaded PLA membrane.

[0016] Furthermore, in step 2, the ratio of silver nitrate to water in the silver nitrate solution is 0.1~0.15g:200mL.

[0017] Further, in step 2, the dopamine-loaded PLA membrane prepared in step 1 is placed in the above silver nitrate solution and left to stand in a water bath at 40~50℃ for 40~48h.

[0018] Further, in step 2, the PLA membrane is removed from the silver nitrate solution and subjected to ultrasonic treatment at 30-50W for 1-8 minutes, then rinsed with deionized water 4-5 times, and placed in an oven at 70-90℃ for 1-5 hours to obtain a stable silver-loaded PLA membrane. The silver loading is 3-8 wt% by weight of the silver-loaded PLA membrane, preferably 5.47%. For example, the silver loading can be 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, 5.5 wt%, 6 wt%, 6.5 wt%, 7 wt%, 7.5 wt%, or 8 wt% by weight of the silver-loaded PLA membrane.

[0019] Further, in step 3, the organic solvent is n-hexane, and the ratio of curing agent to n-hexane is 0.1g~0.15g: 0.05g~0.07g: 20mL.

[0020] Further, in step 3, the silver-supported PLA film prepared in step 2 is pre-wetted with water and then laid flat on a glass petri dish. Using a spray gun at a pressure of 0.1–0.3 MPa, the aforementioned dimethylsiloxane-hexane solution is sprayed onto one side of the silver-supported PLA film at a spray volume of 0.1–0.5 mL / cm². 2 Place it in an oven at 60~90℃ for 3~8 hours, and after taking it out, you will get a silver-loaded PLA-based Janus membrane with one side hydrophilic and the other side hydrophobic.

[0021] The present invention also provides an antibacterial silver-supported PLA-based Janus membrane prepared by the method described in any of the preceding claims.

[0022] Cloth diapers based on the silver-loaded PLA-based Janus membrane as described above as an inner surface layer are manufactured by the following steps: using the silver-loaded PLA-based Janus membrane as the inner surface layer of the cloth diaper, wherein the hydrophobic side of the Janus membrane faces outward toward the skin and the hydrophilic side faces inward toward the absorbent core inside the cloth diaper, thus forming a cloth diaper with hydrophobic, unidirectional moisture-wicking and antibacterial properties.

[0023] Specifically, this invention relates to a method for preparing an antibacterial silver-supported PLA-based Janus membrane, which includes the following steps:

[0024] Step 1: Prepare dopamine-loaded PLA membrane

[0025] Weigh 0.25g~0.3g of dopamine and dissolve it in 100mL of Tris-HCl (pH=8.5) buffer solution using mechanical stirring (200~250 rpm) to prepare a dopamine solution;

[0026] PLA fiber membranes were placed in a dopamine solution and magnetically stirred at 30-35°C for 48 hours. The PLA fiber membranes were then removed from the dopamine solution and rinsed with deionized water 4-5 times to obtain dopamine-loaded PLA membranes.

[0027] Step 2, Preparation of silver-supported PLA film

[0028] Weigh 0.1~0.15g of silver nitrate powder and dissolve it in 200mL of water using magnetic stirring;

[0029] The dopamine-loaded PLA membrane prepared in step 1 was placed in the above silver nitrate solution and allowed to stand in a water bath at 40~50℃ for 48h.

[0030] The PLA membrane was removed from the silver nitrate solution, subjected to ultrasonic treatment at 40W for 2 minutes, rinsed with deionized water 4-5 times, and placed in an oven at 80℃ for 2 hours to obtain a silver-loaded PLA membrane.

[0031] Step 3, Preparation of silver-supported PLA-based Janus film

[0032] Weigh 0.1g~0.15g of dimethylsiloxane and 0.05g~0.07g of curing agent, stir magnetically for 1h, and dissolve in 20mL of n-hexane;

[0033] After pre-wetting the silver-loaded PLA membrane prepared in step 2 with water, it was laid flat on a glass petri dish. Using a spray gun, 10 mL of the above-mentioned PDMS n-hexane solution was sprayed onto one side of the silver-loaded PLA membrane under a pressure of 0.2 MPa. The membrane was then placed in an oven at 80°C for 4 hours. After removal, a silver-loaded PLA-based Janus membrane with one hydrophilic side and the other hydrophobic side was obtained.

[0034] Specifically, the present invention relates to a cloth diaper based on a silver-loaded PLA-based Janus membrane as the inner surface layer, comprising the following steps:

[0035] Step 1: Prepare dopamine-loaded PLA membrane

[0036] Weigh 0.25g~0.3g of dopamine and dissolve it in 100mL of Tris-HCl (pH=8.5) buffer solution using mechanical stirring (200~250 rpm) to prepare a dopamine solution;

[0037] PLA fiber membranes were placed in a dopamine solution and magnetically stirred at 30-35°C for 48 hours. The PLA fiber membranes were then removed from the dopamine solution and rinsed with deionized water 4-5 times to obtain dopamine-loaded PLA membranes.

[0038] Step 2, Preparation of silver-supported PLA film

[0039] Weigh 0.1~0.15g of silver nitrate powder and dissolve it in 200mL of water using magnetic stirring;

[0040] The dopamine-loaded PLA membrane prepared in step 1 was placed in the above silver nitrate solution and allowed to stand in a water bath at 40~50℃ for 48h.

[0041] The PLA membrane was removed from the silver nitrate solution, subjected to ultrasonic treatment at 40W for 2 minutes, rinsed with deionized water 4-5 times, and placed in an oven at 80℃ for 2 hours to obtain a silver-loaded PLA membrane.

[0042] Step 3, Preparation of silver-supported PLA-based Janus film

[0043] Weigh 0.1g~0.15g of PDMS and 0.05g~0.07g of curing agent, stir magnetically for 1h, and dissolve in 20mL of n-hexane;

[0044] After the silver-loaded PLA membrane prepared in step 2 was pre-wetted with water, it was laid flat on a glass petri dish. Using a spray gun at a pressure of 0.2 MPa, 10 mL of the above-mentioned PDMS n-hexane solution was sprayed onto one side of the silver-loaded PLA membrane. The membrane was placed in an oven at 80°C for 4 hours. After removal, a silver-loaded PLA-based Janus membrane with one hydrophilic side and one hydrophobic side was obtained.

[0045] Step 4: Preparation of silver-loaded PLA-based Janus membrane as the inner surface layer of cloth diapers

[0046] The silver-loaded PLA-based Janus membrane prepared in step 3 is used as the inner surface layer of the cloth diaper. The hydrophobic side of the Janus membrane faces outwards towards the skin, and the hydrophilic side faces inwards towards the absorbent core inside the cloth diaper, forming a high-performance cloth diaper with excellent hydrophobicity, unidirectional moisture wicking, and antibacterial properties. The cloth diaper mainly consists of three parts: a unidirectional moisture-wicking inner surface layer, a multi-layered absorbent core with different fabric structures to store urine, and an outer layer to prevent urine leakage.

[0047] The present invention has the following beneficial effects:

[0048] The silver-loaded PLA-based Janus membrane prepared in this invention is used as the inner surface layer of cloth diapers, which significantly improves the one-way moisture wicking performance of the inner surface layer of cloth diapers. Specifically, the pressure rectification ratio of liquid permeation is significantly improved compared with commercial cloth diapers, and the cloth diapers are endowed with antibacterial properties. This invention has important implications for solving the shortcomings of existing cloth diaper inner surface layers, such as poor hydrophobicity and moisture wicking performance and weak antibacterial properties.

[0049] This invention provides a method for preparing an antibacterial silver-loaded PLA-based Janus membrane, and secondly, it involves replacing the inner surface layer of commercial cloth diapers with the prepared silver-loaded PLA-based Janus membrane to construct high-performance cloth diapers. Due to the excellent hydrophobicity, unidirectional moisture wicking, and antibacterial properties of the silver-loaded PLA-based Janus membrane, this invention provides cloth diapers with better comfort and convenience. Attached Figure Description

[0050] Figure 1 These are electron microscope images of the silver-supported PLA-based Janus film in this invention;

[0051] Figure 2 This refers to the contact angles of water on both sides of the silver-supported PLA-based Janus membrane in this invention.

[0052] Figure 3 This is a diagram showing the one-way liquid permeation performance of the silver-supported PLA-based Janus membrane in this invention.

[0053] Figure 4 This is a diagram illustrating the antibacterial properties of the silver-supported PLA-based Janus membrane in this invention.

[0054] Figure 5 This is an image of a high-performance cloth diaper made by replacing the inner surface layer of commercial cloth diapers with an antibacterial silver-supported PLA-based Janus membrane, as described in this invention.

[0055] Figure 6 This is a comparison chart of the pressure rectification ratio on both sides of the inner surface layer of the silver-loaded PLA-based Janus membrane used in this invention and the pressure rectification ratio on both sides of the inner surface layer of three commercial cloth diapers. Detailed Implementation

[0056] The present invention will now be described in further detail with reference to the accompanying drawings.

[0057] Step 1: Prepare dopamine-loaded PLA membrane

[0058] Weigh 0.25 g of dopamine and dissolve it in 100 mL of Tris-HCl (pH=8.5) buffer solution using mechanical stirring (200 rpm) to prepare a dopamine solution;

[0059] PLA fiber membrane (10 μm filament diameter, 20 μm pore size, and 0.396 mm thickness) was placed in a dopamine solution and magnetically stirred at 30°C for 48 h. The PLA fiber membrane was then removed from the dopamine solution and rinsed 5 times with deionized water to obtain a dopamine-loaded PLA membrane.

[0060] Step 2, Preparation of silver-supported PLA film

[0061] Weigh 0.1g of silver nitrate powder and dissolve it in 200mL of water using magnetic stirring;

[0062] The dopamine-loaded PLA membrane prepared in step 1 was placed in the above silver nitrate solution and allowed to stand in a water bath at 40°C for 48 hours.

[0063] The PLA membrane was removed from the silver nitrate solution, subjected to ultrasonic treatment at 40W for 2 minutes, rinsed with deionized water 5 times, and placed in an oven at 80℃ for 2 hours to obtain a silver-loaded PLA membrane.

[0064] Step 3, Preparation of silver-supported PLA-based Janus film

[0065] Weigh 0.1g of the basic component and 0.05g of the curing agent (Dow Corning Sylgard 184 PDMS prepolymer, which consists of separately packaged basic components and curing agents, the basic component being dimethylsiloxane), and dissolve them in 20mL of n-hexane by magnetic stirring for 1h.

[0066] The silver-supported PLA membrane prepared in step 2 was pre-wetted with water and then laid flat on a glass petri dish. Using a spray gun at a pressure of 0.2 MPa, 10 mL of the aforementioned PDMS-n-hexane solution was sprayed onto one side of the silver-supported PLA membrane. The spraying volume of the solution was 0.5 mL / cm². 2 The film was placed in an 80℃ oven for 4 hours. After being removed, a silver-loaded PLA-based Janus membrane with one hydrophilic side and one hydrophobic side was obtained.

[0067] In this invention, the surface morphology of silver-loaded PLA-based Janus films was observed using a scanning electron microscope. Figure 1 Image a shows the surface morphology of the original PLA film; the surface of the original PLA fibers exhibits a smooth structure. (Example image 'a') Figure 1 As shown in Figure b, the hydrophilic side of the PLA fiber surface is covered with a large number of silver particles, of which the silver loading is 5.47 wt% based on the total mass of the silver-loaded PLA film. Figure 1 The surface of the PLA fiber on the hydrophobic side of the middle layer is not only covered with silver particles but also with hydrophobic PDMS. The presence of PDMS on one side gives the PLA membrane Janus wettability.

[0068] like Figure 2 As shown, the contact angles of the prepared silver-loaded PLA-based Janus membrane were measured using a contact angle meter. The contact angle of the hydrophilic side to water was ~0°, and the contact angle of the hydrophobic side to water was ~145°.

[0069] See Figure 3The liquid permeation and backflow prevention process of the PLA-based Janus membrane was recorded using a camera (Nikon camera at a resolution of 1280x720 pixels). When the hydrophobic side is facing upwards, water droplets can spontaneously permeate the Janus membrane under the influence of gravity. Figure 3 As shown in Figure a). When the hydrophilic side is facing upwards, water droplets falling on the surface spread out rapidly and cannot penetrate through the Janus membrane (as shown in Figure a). Figure 3 (As shown in b).

[0070] Figure 4 In accordance with the national standard GB / T 20944.3-2008d Evaluation of antibacterial properties of textiles, the antibacterial properties of silver-loaded PLA film against Escherichia coli, Staphylococcus aureus, and Candida albicans were tested using plate coating count. The results showed that the antibacterial properties were all above 98%.

[0071] Step 5: Preparation of silver-loaded PLA-based Janus membrane as the inner surface layer of cloth diapers.

[0072] Commercial cloth diapers mainly consist of three parts: an inner surface layer with unidirectional moisture wicking; a multi-layered highly absorbent core with different fabric structures to store urine; and an outer layer to prevent urine leakage. The inner surface layer of the commercial cloth diaper is replaced with the silver-loaded PLA-based Janus membrane prepared in step 3, with the hydrophobic side of the Janus membrane facing outwards towards the skin and the hydrophilic side facing inwards towards the absorbent core inside the cloth diaper. Due to the excellent hydrophobicity, unidirectional moisture wicking, and antibacterial properties of the silver-loaded PLA-based Janus membrane, the cloth diaper offers better comfort and convenience. Figure 5 This is an image of a high-performance cloth diaper made by replacing the inner surface layer of commercial cloth diapers with an antibacterial silver-loaded PLA-based Janus membrane, as described in this invention.

[0073] By comparing the pressure rectification ratio on both sides of the inner surface of silver-loaded PLA-based Janus membrane as the inner layer of cloth diapers with the pressure rectification ratio on both sides of the inner surface of commercial cloth diaper brands ( Figure 6 The study found that silver-supported PLA-based Janus membranes exhibit better unidirectional moisture conductivity. The pressure rectification ratio test method for the membrane was as follows: the critical penetration pressure for water to permeate from the hydrophobic side to the hydrophilic side of the Janus membrane and the critical penetration pressure for water to permeate from the hydrophilic side to the hydrophobic side of the Janus membrane were measured using the water column height measurement method. The ratio of these two critical penetration pressures was defined as the pressure rectification ratio of the Janus membrane.

[0074] This invention provides two main aspects: firstly, a method for preparing an antibacterial silver-loaded PLA-based Janus membrane; and secondly, the replacement of the inner surface layer of commercial cloth diapers with the prepared silver-loaded PLA-based Janus membrane to construct high-performance cloth diapers. This invention aims to address the problems encountered in promoting the application of cloth diapers, such as poor hydrophobicity and moisture wicking properties of the inner surface layer, weak antibacterial performance, and consequently, poor comfort and convenience.

[0075] The parts of this invention not described in detail are well-known to those skilled in the art. The embodiments described above are merely preferred embodiments of the invention, and do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Various modifications and improvements to the technical solutions of this invention made by those skilled in the art without departing from the spirit of the invention should fall within the protection scope defined by the claims of this invention.

Claims

1. A cloth diaper with an inner surface layer composed of an antibacterial silver-loaded PLA-based Janus membrane, characterized in that, The cloth diaper is prepared by the following steps: using the silver-loaded PLA-based Janus membrane as the inner surface layer of the cloth diaper, wherein the hydrophobic side of the Janus membrane faces outward toward the skin, and the hydrophilic side faces inward toward the absorbent core inside the cloth diaper, forming a cloth diaper with hydrophobic, unidirectional moisture-wicking, and antibacterial properties. The preparation method of the antibacterial silver-loaded PLA-based Janus membrane includes the following steps: Step 1: Prepare dopamine-loaded PLA membrane PLA fiber membranes were placed in a dopamine solution and stirred. The PLA fiber membranes were then removed from the dopamine solution and washed to obtain dopamine-loaded PLA membranes. The PLA fiber membranes had a filament diameter of 1-10 μm, a pore size of 1-20 μm, and a membrane thickness of 0.1-1 mm. Step 2, Preparation of silver-supported PLA film The dopamine-loaded PLA membrane prepared in step 1 was placed in silver nitrate solution and allowed to stand in a water bath. The PLA membrane was removed from the silver nitrate solution, ultrasonically treated, washed, and dried. The purpose of ultrasonic treatment was to remove excess silver particles from the porous surface structure, thereby obtaining a stable silver-loaded PLA membrane. The silver loading was 3–7.5 wt% by weight of the silver-loaded PLA membrane. Step 3, Preparation of silver-supported PLA-based Janus film Dimethylsiloxane and a curing agent are dissolved in n-hexane to obtain a dimethylsiloxane solution; After pre-wetting the silver-loaded PLA membrane prepared in step 2 with water, it is laid flat, and the dimethylsiloxane solution is sprayed onto one side of the silver-loaded PLA membrane. After drying, it is removed to obtain a silver-loaded PLA-based Janus membrane with one hydrophilic side and one hydrophobic side. In step 1, the dopamine solution is prepared by the following method: weighing dopamine and dissolving it in Tris-HCl buffer solution using mechanical stirring to prepare a dopamine solution, wherein the ratio of dopamine to buffer solution is 0.25g~0.3g:100mL, and the pH of the buffer solution is 8~9; In step 1, the PLA fiber membrane is placed in a dopamine solution and magnetically stirred at 30-35°C for 40-48 hours. Then, the PLA fiber membrane is removed from the dopamine solution and rinsed with deionized water 4-5 times to obtain a dopamine-loaded PLA membrane.

2. The cloth diaper according to claim 1, characterized in that, In step 2, the ratio of silver nitrate to water in the silver nitrate solution is 0.1~0.15g:200mL.

3. The cloth diaper according to claim 1, characterized in that, In step 2, the dopamine-loaded PLA membrane prepared in step 1 is placed in the above silver nitrate solution and left to stand in a water bath at 40~50℃ for 40~48h.

4. The cloth diaper according to claim 1, characterized in that, In step 2, the PLA membrane is removed from the silver nitrate solution, subjected to ultrasonic treatment at 30-50W for 1-8 minutes, rinsed with deionized water 4-5 times, and placed in an oven at 70-90℃ for 1-5 hours to obtain a stable silver-loaded PLA membrane, wherein the silver loading is 3.5-7wt% based on the mass of the silver-loaded PLA membrane.

5. The cloth diaper according to claim 1, characterized in that, In step 3, the ratio of dimethylsiloxane: curing agent: n-hexane is 0.1g~0.15g: 0.05g~0.07g: 20mL.

6. The cloth diaper according to claim 1, characterized in that, In step 3, the silver-supported PLA membrane prepared in step 2 is pre-wetted with water and then laid flat on a glass petri dish. A dimethylsiloxane-hexane solution is then sprayed onto one side of the silver-supported PLA membrane using a spray gun at a pressure of 0.1–0.3 MPa. The spraying volume of the solution is 0.1–0.5 mL / cm². 2 Place it in an oven at 60~90℃ for 3~8 hours, and after taking it out, you will get a silver-loaded PLA-based Janus membrane with one side hydrophilic and the other side hydrophobic.

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