Antibacterial skin-friendly polylactic acid non-woven fabric, preparation method and application on wet wipes

Abstract

This invention relates to the field of nonwoven fabric technology, specifically to an antibacterial and skin-friendly polylactic acid (PLA) nonwoven fabric, its preparation method, and its application in wet wipes. The preparation method includes: Step 1, reacting vinylsiloxane monomer and dimethylaminoethyl methacrylate to prepare an organosilicon-tertiary amine copolymer; Step 2, reacting the organosilicon-tertiary amine copolymer with a quaternizing agent to prepare an organosilicon-quaternary ammonium salt copolymer; Step 3, melt-blending the organosilicon-quaternary ammonium salt copolymer with a polylactic acid matrix resin, extruding and pelletizing to obtain an antibacterial modified PLA masterbatch; Step 4, drying the antibacterial modified PLA masterbatch, followed by spinning, web laying, and hot rolling reinforcement to obtain the antibacterial and skin-friendly PLA nonwoven fabric. This invention fixes the quaternary ammonium salt to the polymer backbone in a covalent bond manner, endowing the nonwoven fabric with highly efficient and long-lasting antibacterial properties; the introduced side-chain siloxane spontaneously migrates to the fiber surface during spinning, reducing the coefficient of friction and simultaneously generating an internal plasticizing effect, significantly improving softness and skin-friendliness.

Description

Technical Field

[0001] This invention relates to the field of nonwoven fabric technology, specifically to an antibacterial and skin-friendly polylactic acid nonwoven fabric, its preparation method, and its application in wet wipes. Background Technology

[0002] With the popularization of environmental protection concepts and consumers' pursuit of healthy lifestyles, replacing traditional petroleum-based products with bio-based biodegradable materials has become a clear development direction in the disposable hygiene products sector. Polylactic acid (PLA), due to its excellent biocompatibility, complete biodegradability, and its origin in renewable resources, shows broad application prospects in daily care products that come into direct contact with the skin, such as wet wipes. Developing PLA-based environmentally friendly wet wipe substrates aligns with the social needs of sustainable development.

[0003] To impart antibacterial properties to polylactic acid (PLA) nonwoven fabrics to meet the hygiene requirements of wet wipes and improve their comfort (skin-friendliness) in contact with skin, existing technologies mainly follow these paths: First, physical blending, which involves directly melt-blending inorganic nano-antibacterial agents (such as nano-silver, zinc oxide) or organic antibacterial agents (such as triclosan) with PLA. This method often results in uneven dispersion due to poor compatibility between the antibacterial agent and the matrix, affecting spinning stability and the mechanical properties of the finished product. Inorganic particles are prone to agglomeration, which may cause skin friction, while some small-molecule organic antibacterial agents (such as triclosan) pose potential skin irritation and the risk of migration and precipitation in the liquid environment of wet wipes. Second, finishing processes, which involve impregnating or coating the formed PLA nonwoven fabric to load antibacterial components. While this method can partially preserve the physical properties of the substrate, the coating has weak adhesion to the fibers and is easily detached during wiping, resulting in a short-lasting antibacterial effect. Simultaneously, the outer coating may clog fiber pores, affecting the breathability and moisture permeability of the nonwoven fabric, its natural biodegradability, and potentially altering its soft feel. Thirdly, introducing functional antibacterial segments into the PLA molecular chain through copolymerization modification can achieve structurally stable antibacterial properties, but the synthesis process is complex and costly, and the control over the skin-friendly softness of the final material is often insufficient. Furthermore, some studies have attempted to introduce antibacterial functions by pre-synthesizing functional polymers and then blending them with PLA; however, existing reports mostly focus on achieving single functions. How to synergistically achieve highly efficient and long-lasting antibacterial properties, excellent skin-friendly feel, and good mechanical properties within the same system remains an unsolved technical challenge.

[0004] To address the shortcomings of existing technologies, if antibacterial functional groups and skin-friendly modified components can be pre-bonded to the same polymer chain through molecular structure design, and then blended with a PLA matrix, it is expected to simplify the process while achieving multifunctional synergy. Therefore, developing an antibacterial and skin-friendly polylactic acid nonwoven fabric material that can comprehensively meet the above-mentioned high-performance requirements is of great significance for promoting the product upgrade of high-end environmentally friendly wet wipes. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide an antibacterial and skin-friendly polylactic acid nonwoven fabric, its preparation method, and its application in wet wipes, thereby solving the problems of insufficient antibacterial function, inadequate skin-friendly softness, and difficulty in synergistically improving mechanical properties and functions in the prior art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing an antibacterial and skin-friendly polylactic acid nonwoven fabric includes the following steps: Step 1: Under nitrogen protection, vinylsiloxane monomer, dimethylaminoethyl methacrylate (DMAEMA) and free radical initiator are dissolved in organic solvent 1 and reacted. After the reaction is completed, the mixture is separated, purified, and dried to obtain organosilicon-tertiary amine copolymer. Step 2: Dissolve the organosilicon-tertiary amine copolymer in polar organic solvent 2, add quaternizing agent, react, and after the reaction is completed, separate and purify, dry, and obtain organosilicon-quaternary ammonium salt copolymer; Step 3: Melt-blend the organosilicon-quaternary ammonium salt copolymer with polylactic acid matrix resin, then extrude, cool, and pelletize to obtain antibacterial modified polylactic acid masterbatch; Step 4: After drying the antibacterial modified polylactic acid masterbatch, it is spun, web-laid, and hot-rolled for reinforcement to obtain antibacterial and skin-friendly polylactic acid nonwoven fabric.

[0007] Preferably, in step one, the molar ratio of vinylsiloxane monomer to dimethylaminoethyl methacrylate is (1-3):(7-9), the amount of free radical initiator added is 0.5%-2% of the total mass of vinylsiloxane monomer and dimethylaminoethyl methacrylate, the amount of organic solvent 1 is 4-8 times the total mass of vinylsiloxane monomer and dimethylaminoethyl methacrylate, and the reaction conditions are: under nitrogen protection, stirring at 60-80°C for 6-12 hours.

[0008] Preferably, the vinylsiloxane monomer comprises γ-methacryloyloxypropyltrimethoxysilane (silane coupling agent KH570), the free radical initiator comprises azobisisobutyronitrile (AIBN), and the organic solvent 1 comprises toluene.

[0009] Preferably, in step two, the amount of quaternizing agent added is such that the molar ratio of the quaternizing agent to the dimethylaminoethyl methacrylate structural unit in the organosilicon-tertiary amine copolymer is (0.5-1.2):1, the amount of organic solvent 2 is 5-15 times the mass of the organosilicon-tertiary amine copolymer, and the reaction conditions are stirring at 60-70℃ for 12-24 hours.

[0010] Preferably, the quaternizing agent comprises dodecane bromide, and the organic solvent 2 comprises dimethyl sulfoxide (DMSO).

[0011] Preferably, in step three, the mass ratio of the organosilicon-quaternary ammonium salt copolymer to the polylactic acid matrix resin is (5-20):(80-95), and the melting temperature is 180-200℃.

[0012] Preferably, in step four, spinning includes: drying the antibacterial modified polylactic acid masterbatch, and then obtaining polylactic acid fiber through melt spinning, winding, stretching, and heat setting processes; The spinning temperature is 200-230℃, the winding speed is 800-1500m / min, the drawing temperature is 70-90℃, the drawing ratio is 2.5-4 times, the heat setting temperature is 90-110℃, and the monofilament fineness of polylactic acid fiber is 1.5-3dtex.

[0013] Preferably, in step four, the web is laid in a cross-lay method, and the web weight is 40-60 g / m². 2 .

[0014] Preferably, in step four, the hot rolling temperature is 60-100℃, the rolling speed is 10-30m / min, and the linear pressure is 20-50N / mm.

[0015] The present invention also discloses an antibacterial and skin-friendly polylactic acid nonwoven fabric prepared by the method described above.

[0016] An application of antibacterial and skin-friendly polylactic acid nonwoven fabric, as described above, in wet wipes.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention obtains an organosilicon-quaternary ammonium salt copolymer by copolymerizing and quaternizing vinylsiloxane with N,N-dimethylaminoethyl methacrylate. In this copolymer, the antibacterial active center of the quaternary ammonium salt is fixed in the polymer backbone by covalent bonds. During the melt blending process, the organosilicon-quaternary ammonium salt copolymer molecular chain is uniformly distributed in the polylactic acid matrix due to the entanglement between the molecular chain and the polylactic acid molecular chain, which can endow polylactic acid nonwoven fabric with excellent antibacterial properties. This invention introduces γ-methacryloxypropyltrimethoxysilane as a comonomer. Its siloxane structure is attached to the polymer backbone in the form of side chains. During melt spinning, the side chain siloxane spontaneously migrates to the fiber surface due to its low surface energy characteristics, forming a surface enrichment layer. This can reduce the coefficient of friction of the fiber surface, giving polylactic acid nonwoven fabric a soft and smooth feel and enhancing skin-friendliness. At the same time, the large steric hindrance of the side chain siloxane increases the free volume between polylactic acid molecular chains, producing an internal plasticizing effect, which can improve the flexibility of polylactic acid nonwoven fabric and further enhance skin-friendliness. This invention introduces ester groups through γ-methacryloxypropyltrimethoxysilane and dimethylaminoethyl methacrylate, which are highly similar in structure to the ester groups of the polylactic acid (PLA) backbone. Based on the principle of "like dissolves like," the presence of similar functional groups significantly reduces the interfacial free energy between the copolymer and the PLA matrix, resulting in a high degree of matching in solubility parameters. This ensures good compatibility from a thermodynamic perspective. The dipole-dipole interactions and weak transesterification reactions between the ester groups further form interfacial anchoring points, promoting the uniform micro-dispersion of the functional polymer within the PLA matrix and preventing macro-phase separation. This allows for uniform coverage of the antibacterial function of the quaternary ammonium salt and full utilization of the surface enrichment effect of the siloxane. In addition, the enhanced interfacial bonding force enables effective stress transfer, thereby improving the tensile strength of the PLA nonwoven fabric. This achieves a synergistic improvement in the antibacterial, skin-friendly, and mechanical properties of the PLA nonwoven fabric. Attached Figure Description

[0018] Figure 1 The graph shows the results of the antibacterial properties test of the polylactic acid nonwoven fabrics prepared in Examples 1-3 and Comparative Examples 1-3 of this invention. Figure 2 The graph shows the results of the soft and skin-friendly properties of the polylactic acid nonwoven fabrics prepared in Examples 1-3 and Comparative Examples 1-3 of this invention. Figure 3 The graph shows the mechanical property test results of the polylactic acid nonwoven fabrics prepared in Examples 1-3 and Comparative Examples 1-3 of this invention. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0020] Example 1: This example provides a method for preparing antibacterial and skin-friendly polylactic acid nonwoven fabric, including the following steps: Step 1: Preparation of organosilicon-tertiary amine copolymer: Under nitrogen protection, γ-methacryloxypropyltrimethoxysilane, dimethylaminoethyl methacrylate, and azobisisobutyronitrile were dissolved in toluene. The mixture was stirred at 60°C for 12 h under nitrogen protection. After the reaction was completed, the reaction solution was added dropwise to 10 times the volume of petroleum ether for precipitation. The mixture was filtered, and the precipitate was washed three times with petroleum ether and dried under vacuum at 40°C to constant weight to obtain an organosilicon-tertiary amine copolymer. The molar ratio of γ-methacryloxypropyltrimethoxysilane to dimethylaminoethyl methacrylate is 1:9, the amount of azobisisobutyronitrile added is 0.5% of the total mass of γ-methacryloxypropyltrimethoxysilane and dimethylaminoethyl methacrylate, and the amount of toluene is 4 times the total mass of vinylsiloxane monomer and dimethylaminoethyl methacrylate. Step 2: Preparation of organosilicon-quaternary ammonium salt copolymer: The organosilicon-tertiary amine copolymer was dissolved in dimethyl sulfoxide, and bromododecane was added. The mixture was stirred at 60°C for 24 hours. After the reaction was completed, the reaction solution was added dropwise to 10 times the volume of acetone for precipitation. The mixture was filtered, and the precipitate was washed three times with acetone and dried under vacuum at 40°C to constant weight to obtain the organosilicon-quaternary ammonium salt copolymer. The amount of bromododecane added is such that the molar ratio of bromododecane to the dimethylaminoethyl methacrylate structural unit in the organosilicon-tertiary amine copolymer is 0.5:1, and the amount of dimethyl sulfoxide is 5 times the mass of the organosilicon-tertiary amine copolymer. Step 3: Preparation of antibacterial modified polylactic acid masterbatch: The organosilicon-quaternary ammonium salt copolymer and polylactic acid matrix resin (L-polylactic acid with a weight average molecular weight of 150,000) were melt-blended. The mass ratio of organosilicon-quaternary ammonium salt copolymer to polylactic acid matrix resin was 5:95, and the melting temperature was 180℃. The melt was extruded, cooled, and pelletized to obtain antibacterial modified polylactic acid masterbatch. Step 4: Preparation of antibacterial and skin-friendly polylactic acid nonwoven fabric: S1. Spinning: Antibacterial modified polylactic acid masterbatch is vacuum dried at 80℃ for 8 hours, and polylactic acid fiber is obtained through melt spinning, winding, stretching and heat setting processes. The spinning temperature is 200℃, the winding speed is 800m / min, the drawing temperature is 70℃, the drawing ratio is 2.5 times, the heat setting temperature is 90℃, and the monofilament fineness of polylactic acid fiber is 3dtex. S2. Web laying: Polylactic acid fibers are laid into a web by cross-laying, and the web weight is 40g / m². S3. Hot rolling reinforcement: The fiber web is hot rolled to reinforce it. The hot rolling temperature is 60℃, the machine speed is 10m / min, and the linear pressure is 50N / mm to obtain antibacterial and skin-friendly polylactic acid nonwoven fabric.

[0021] Example 2: This example provides a method for preparing antibacterial and skin-friendly polylactic acid nonwoven fabric, including the following steps: Step 1: Preparation of organosilicon-tertiary amine copolymer: Under nitrogen protection, γ-methacryloxypropyltrimethoxysilane, dimethylaminoethyl methacrylate, and azobisisobutyronitrile were dissolved in toluene. The mixture was stirred at 80°C for 6 hours under nitrogen protection. After the reaction was completed, the reaction solution was added dropwise to 10 times the volume of petroleum ether for precipitation. The mixture was filtered, and the precipitate was washed three times with petroleum ether and dried under vacuum at 40°C to constant weight to obtain an organosilicon-tertiary amine copolymer. The molar ratio of γ-methacryloxypropyltrimethoxysilane to dimethylaminoethyl methacrylate is 3:7, the amount of azobisisobutyronitrile added is 2% of the total mass of γ-methacryloxypropyltrimethoxysilane and dimethylaminoethyl methacrylate, and the amount of toluene is 8 times the total mass of vinylsiloxane monomer and dimethylaminoethyl methacrylate. Step 2: Preparation of organosilicon-quaternary ammonium salt copolymer: The organosilicon-tertiary amine copolymer was dissolved in dimethyl sulfoxide, and bromododecane was added. The mixture was stirred at 70°C for 12 hours. After the reaction was completed, the reaction solution was added dropwise to 10 times the volume of acetone for precipitation. The mixture was filtered, and the precipitate was washed three times with acetone and dried under vacuum at 40°C to constant weight to obtain the organosilicon-quaternary ammonium salt copolymer. The amount of bromododecane added is such that the molar ratio of bromododecane to the dimethylaminoethyl methacrylate structural unit in the organosilicon-tertiary amine copolymer is 1.2:1, and the amount of dimethyl sulfoxide is 15 times the mass of the organosilicon-tertiary amine copolymer. Step 3: Preparation of antibacterial modified polylactic acid masterbatch: The organosilicon-quaternary ammonium salt copolymer and polylactic acid matrix resin (L-polylactic acid with a weight average molecular weight of 150,000) were melt-blended. The mass ratio of organosilicon-quaternary ammonium salt copolymer to polylactic acid matrix resin was 20:80, and the melting temperature was 200℃. The melt was extruded, cooled, and pelletized to obtain antibacterial modified polylactic acid masterbatch. Step 4: Preparation of antibacterial and skin-friendly polylactic acid nonwoven fabric: S1. Spinning: Antibacterial modified polylactic acid masterbatch is vacuum dried at 80℃ for 8 hours, and polylactic acid fiber is obtained through melt spinning, winding, stretching and heat setting processes. The spinning temperature is 230℃, the winding speed is 1500m / min, the drawing temperature is 90℃, the drawing ratio is 4 times, the heat setting temperature is 110℃, and the monofilament fineness of polylactic acid fiber is 1.5dtex. S2. Web laying: Polylactic acid fibers are laid into a web by cross-laying, and the web weight is 60g / m². S3. Hot rolling reinforcement: The fiber web is hot rolled and reinforced at a temperature of 100℃, a speed of 30m / min, and a linear pressure of 20N / mm to obtain antibacterial and skin-friendly polylactic acid nonwoven fabric.

[0022] Example 3: This example provides a method for preparing antibacterial and skin-friendly polylactic acid nonwoven fabric, including the following steps: Step 1: Preparation of organosilicon-tertiary amine copolymer: Under nitrogen protection, γ-methacryloxypropyltrimethoxysilane, dimethylaminoethyl methacrylate, and azobisisobutyronitrile were dissolved in toluene. The mixture was stirred at 70°C for 9 hours under nitrogen protection. After the reaction was completed, the reaction solution was added dropwise to 10 times the volume of petroleum ether for precipitation. The mixture was filtered, and the precipitate was washed three times with petroleum ether and dried under vacuum at 40°C to constant weight to obtain an organosilicon-tertiary amine copolymer. The molar ratio of γ-methacryloxypropyltrimethoxysilane to dimethylaminoethyl methacrylate is 2:8, the amount of azobisisobutyronitrile added is 1.2% of the total mass of γ-methacryloxypropyltrimethoxysilane and dimethylaminoethyl methacrylate, and the amount of toluene is 6 times the total mass of vinylsiloxane monomer and dimethylaminoethyl methacrylate. Step 2: Preparation of organosilicon-quaternary ammonium salt copolymer: The organosilicon-tertiary amine copolymer was dissolved in dimethyl sulfoxide, and bromododecane was added. The mixture was stirred at 65°C for 18 hours. After the reaction was completed, the reaction solution was added dropwise to 10 times the volume of acetone for precipitation. The precipitate was filtered, washed three times with acetone, and dried under vacuum at 40°C to constant weight to obtain the organosilicon-quaternary ammonium salt copolymer. The amount of bromododecane added is such that the molar ratio of bromododecane to the dimethylaminoethyl methacrylate structural unit in the organosilicon-tertiary amine copolymer is 0.8:1, and the amount of dimethyl sulfoxide is 10 times the mass of the organosilicon-tertiary amine copolymer. Step 3: Preparation of antibacterial modified polylactic acid masterbatch: The organosilicon-quaternary ammonium salt copolymer and polylactic acid matrix resin (L-polylactic acid with a weight average molecular weight of 150,000) were melt-blended. The mass ratio of organosilicon-quaternary ammonium salt copolymer to polylactic acid matrix resin was 12:88, and the melting temperature was 190℃. The melt was extruded, cooled, and pelletized to obtain antibacterial modified polylactic acid masterbatch. Step 4: Preparation of antibacterial and skin-friendly polylactic acid nonwoven fabric: S1. Spinning: Antibacterial modified polylactic acid masterbatch is vacuum dried at 80℃ for 8 hours, and polylactic acid fiber is obtained through melt spinning, winding, stretching and heat setting processes. The spinning temperature is 215℃, the winding speed is 1200m / min, the drawing temperature is 80℃, the drawing ratio is 3.5 times, the heat setting temperature is 100℃, and the single filament fineness of polylactic acid fiber is 2.2dtex. S2. Web laying: Polylactic acid fibers are laid into a web by cross-laying, and the web weight is 50g / m². S3. Hot rolling reinforcement: The fiber web is hot rolled to reinforce it. The hot rolling temperature is 80℃, the machine speed is 20m / min, and the linear pressure is 35N / mm to obtain antibacterial and skin-friendly polylactic acid nonwoven fabric.

[0023] Comparative Example 1: Compared with Example 1, the difference in Comparative Example 1 is that when preparing the polymer modified component, the polymer monomer is only dimethylaminoethyl methacrylate, and γ-methacryloyloxypropyltrimethoxysilane is not added.

[0024] Comparative Example 2: Compared with Example 1, the difference in Comparative Example 2 is that when preparing the polymer modified component, the polymer modified component is an organosilicon-tertiary amine copolymer, rather than an organosilicon-quaternary ammonium salt copolymer obtained by quaternization treatment of organosilicon-tertiary amine copolymer.

[0025] Comparative Example 3: This comparative example provides a method for preparing antibacterial and skin-friendly polylactic acid nonwoven fabric, including the following steps: Step 1: Take γ-methacryloxypropyltrimethoxysilane and dimethylaminoethyl methacrylate, with a molar ratio of γ-methacryloxypropyltrimethoxysilane to dimethylaminoethyl methacrylate of 1:9. The dimethylaminoethyl methacrylate was dissolved in dimethyl sulfoxide, and bromododecane was added. The molar ratio of bromododecane to dimethylaminoethyl methacrylate was 0.5:1. The mixture was stirred at 60°C for 24 hours. After the reaction was completed, the reaction solution was dropped into acetone at 10 times its volume to precipitate the precipitate. The precipitate was filtered, washed three times with acetone, and dried under vacuum at 40°C to obtain quaternized dimethylaminoethyl methacrylate. A mixed modifier was obtained by mixing γ-methacryloxypropyltrimethoxysilane with quaternized dimethylaminoethyl methacrylate. Step 2: Melt-blend the mixed modifier with polylactic acid matrix resin (L-polylactic acid, weight average molecular weight of 150,000). The mass ratio of the mixed modifier to the polylactic acid matrix resin is 5:95, the melting temperature is 180℃, the melt is extruded, cooled, and pelletized to obtain antibacterial modified polylactic acid masterbatch. Step 3: Preparation of antibacterial and skin-friendly polylactic acid nonwoven fabric: S1. Spinning: Antibacterial modified polylactic acid masterbatch is vacuum dried at 80℃ for 8 hours, and polylactic acid fiber is obtained through melt spinning, winding, stretching and heat setting processes. The spinning temperature is 200℃, the winding speed is 800m / min, the drawing temperature is 70℃, the drawing ratio is 2.5 times, the heat setting temperature is 90℃, and the monofilament fineness of polylactic acid fiber is 3dtex. S2. Web laying: Polylactic acid fibers are laid into a web by cross-laying, and the web weight is 40g / m². S3. Hot rolling reinforcement: The fiber web is hot rolled to reinforce it. The hot rolling temperature is 60℃, the machine speed is 10m / min, and the linear pressure is 50N / mm to obtain antibacterial and skin-friendly polylactic acid nonwoven fabric.

[0026] Performance testing: The performance of polylactic acid nonwoven fabric samples prepared in Examples 1-3 and Comparative Examples 1-3 was determined.

[0027] (1) Antibacterial performance test: The inhibition rate of nonwoven fabric samples against Staphylococcus aureus ATCC6538 and Escherichia coli ATCC25922 was determined according to the standard GB / T20944.2-2007 "Evaluation of antibacterial properties of textiles - Part 2: Absorption method". The nonwoven fabric samples were washed according to the standard GB / T8629-2017 "Domestic washing and drying procedures for testing textiles". After 10 washes, the antibacterial rate was determined again according to the above method. The test results are shown in Table 1. Table 1

[0028] As shown in Table 1, the polylactic acid nonwoven fabric prepared by this invention has excellent antibacterial properties, and still maintains a high antibacterial rate after 10 washes. This indicates that the present invention achieves efficient and long-lasting antibacterial function by fixing the quaternary ammonium salt antibacterial active center to the polymer backbone in the form of covalent bonds. Compared with Example 1, in Comparative Example 1, all the polymer monomers were dimethylaminoethyl methacrylate, the quaternary ammonium salt content was slightly increased, and the antibacterial rate showed a slight increase, indicating that the introduction of organosilicon components does not affect the antibacterial activity of quaternary ammonium salts; in Comparative Example 2, no quaternary ammonium salt was formed, and the antibacterial rate dropped sharply, indicating that quaternary ammonium salt is the core source of the antibacterial function of the present invention; in Comparative Example 3, the initial antibacterial rate was high, but it dropped significantly after washing, indicating that the functional components that are not chemically bonded are easily migrated and lost during washing, resulting in poor antibacterial durability.

[0029] (2) Softness and skin-friendly performance test: Refer to standard EDANA WSP 90.3.(05) to determine the softness (mN) of the nonwoven fabric sample. The smaller the mN value, the softer the sample. The test results are shown in Table 2. Table 2

[0030] As shown in Table 2, the polylactic acid nonwoven fabric prepared by this invention exhibits good softness and skin-friendly properties. Compared with Example 1, in Comparative Example 1, without the addition of γ-methacryloyloxypropyltrimethoxysilane, the softness significantly increased while the skin-friendly properties decreased, proving that organosilicon is the key component that imparts softness to the material; in Comparative Example 2, the softness was basically the same as that of Example 1, indicating that the introduction of quaternary ammonium salt had no significant effect on the softness; in Comparative Example 3, the softness was significantly improved, indicating that the unpolymerized modified monomer is easily volatilized and escaped during processing, the actual residual amount of organosilicon is reduced, and the surface enrichment effect is weakened.

[0031] (3) Mechanical property testing: The nonwoven fabric sample was cut into strips of 50mm × 200mm. Referring to standard GB / T3923.1-2013 "Textiles - Tensile Properties of Fabrics - Part 1: Determination of Breaking Strength and Elongation at Break (Strip Method)", a universal testing machine was used with a clamping distance of 100mm and a tensile speed of 100mm / min to determine the breaking strength and elongation at break of the sample. The results are shown in Table 3. Table 3

[0032] As shown in Table 3, the polylactic acid nonwoven fabric prepared by this invention has good mechanical properties, with high tensile strength and elongation at break, achieving a synergistic improvement in antibacterial and skin-friendly functions and mechanical properties. Compared with Example 1, in Comparative Example 1, no γ-methacryloyloxypropyltrimethoxysilane was added when preparing the polymer modification component, resulting in a decrease in mechanical properties. This indicates that the internal plasticizing effect of the organosilicon side chain plays an important role in improving the brittleness of polylactic acid and increasing the elongation at break. In Comparative Example 2, no quaternary ammonium salt was formed, and the mechanical properties were comparable to those of Example 1, indicating that the quaternary ammonium salt had no significant negative impact on mechanical properties. In Comparative Example 3, the modified monomer and polylactic acid were physically mixed without forming a polymer. The polymer was easily volatilized and escaped during processing, resulting in weak interfacial bonding. The tensile strength and elongation at break were significantly lower than those of Example 1.

[0033] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an antibacterial and skin-friendly polylactic acid nonwoven fabric, characterized in that, Includes the following steps: Step 1: Under nitrogen protection, vinylsiloxane monomer, dimethylaminoethyl methacrylate and free radical initiator are dissolved in organic solvent 1 and reacted. After the reaction is completed, the mixture is separated, purified and dried to obtain organosilicon-tertiary amine copolymer. Step 2: Dissolve the organosilicon-tertiary amine copolymer in polar organic solvent 2, add quaternizing agent, react, and after the reaction is completed, separate and purify, dry, and obtain organosilicon-quaternary ammonium salt copolymer; Step 3: Melt-blend the organosilicon-quaternary ammonium salt copolymer with polylactic acid matrix resin, then extrude, cool, and pelletize to obtain antibacterial modified polylactic acid masterbatch; Step 4: After drying the antibacterial modified polylactic acid masterbatch, it is spun, web-laid, and hot-rolled for reinforcement to obtain antibacterial and skin-friendly polylactic acid nonwoven fabric.

2. The method for preparing an antibacterial and skin-friendly polylactic acid nonwoven fabric according to claim 1, characterized in that, In step one, the molar ratio of vinylsiloxane monomer to dimethylaminoethyl methacrylate is (1-3):(7-9), the amount of free radical initiator added is 0.5%-2% of the total mass of vinylsiloxane monomer and dimethylaminoethyl methacrylate, the amount of organic solvent 1 is 4-8 times the total mass of vinylsiloxane monomer and dimethylaminoethyl methacrylate, and the reaction conditions are: under nitrogen protection, stirring at 60-80℃ for 6-12 hours.

3. The method for preparing an antibacterial and skin-friendly polylactic acid nonwoven fabric according to claim 2, characterized in that, The vinylsiloxane monomer includes γ-methacryloyloxypropyltrimethoxysilane, the free radical initiator includes azobisisobutyronitrile, and the organic solvent 1 includes toluene.

4. The method for preparing an antibacterial and skin-friendly polylactic acid nonwoven fabric according to claim 1, characterized in that, In step two, the amount of quaternizing agent added is such that the molar ratio of quaternizing agent to dimethylaminoethyl methacrylate structural unit in organosilicon-tertiary amine copolymer is (0.5-1.2):1, the amount of organic solvent 2 is 5-15 times the mass of organosilicon-tertiary amine copolymer, and the reaction conditions are stirring at 60-70℃ for 12-24h. The quaternizing agent includes dodecane bromide, and the organic solvent 2 includes dimethyl sulfoxide.

5. The method for preparing an antibacterial and skin-friendly polylactic acid nonwoven fabric according to claim 1, characterized in that, In step three, the mass ratio of organosilicon-quaternary ammonium salt copolymer to polylactic acid matrix resin is (5-20):(80-95), and the melting temperature is 180-200℃.

6. The method for preparing an antibacterial and skin-friendly polylactic acid nonwoven fabric according to claim 1, characterized in that, In step four, spinning includes: drying the antibacterial modified polylactic acid masterbatch, and then obtaining polylactic acid fiber through melt spinning, winding, stretching, and heat setting processes; The spinning temperature is 200-230℃, the winding speed is 800-1500m / min, the drawing temperature is 70-90℃, the drawing ratio is 2.5-4 times, the heat setting temperature is 90-110℃, and the monofilament fineness of polylactic acid fiber is 1.5-3dtex.

7. The method for preparing an antibacterial and skin-friendly polylactic acid nonwoven fabric according to claim 1, characterized in that, In step four, the web is laid in a cross-laying manner, and the web weight is 40-60 g / m². 2 .

8. The method for preparing an antibacterial and skin-friendly polylactic acid nonwoven fabric according to claim 1, characterized in that, In step four, the hot rolling temperature is 60-100℃, the rolling speed is 10-30m / min, and the linear pressure is 20-50N / mm.

9. An antibacterial and skin-friendly polylactic acid nonwoven fabric prepared by the method described in any one of claims 1-8.

10. The application of the antibacterial and skin-friendly polylactic acid nonwoven fabric as described in claim 9 in wet wipes.

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