Water-soluble chitosan fiber mask and production process thereof

Abstract

The invention provides a water-soluble chitosan fiber mask and a production process thereof, and mainly relates to the technical field of mask production, and the production process comprises the following steps: mixing and dispersing chitosan and a surfactant solution, and carrying out plasma treatment on a fiber material; carrying out gradient mixing on the pretreated chitosan and a fiber material in the presence of a dispersing agent; preparing a fiber base material through needling, spunlace and hot melting bonding processes; immersing the mixed fiber base material in a mixed solution of acid containing chitosan and ethanol under a negative pressure condition, wherein the mass ratio of the chitosan to the mixed solution is 1: 0.2-1: 2; and removing ethanol through reduced pressure distillation, recovering, and drying to obtain the water-soluble chitosan mask. By optimizing chitosan dispersion, fiber activation, a gradient structure and negative pressure permeation design, the technical problems that chitosan is poor in dispersity, molecules are easy to degrade and load is uneven in a mask base material are systematically solved, and meanwhile collaborative optimization of the instant solubility of the mask and slow release of active ingredients is achieved.

Description

Technical Field

[0001] The present invention mainly relates to the technical field of facial mask production processes, and specifically to a water-soluble chitosan fiber facial mask and its production process. Background Art

[0002] With the increasing demand of consumers for skin care efficacy and convenience, facial mask products have gradually evolved from a single moisturizing function to a multi-functional and integrated design. Currently, most commercially available facial masks use a facial mask cloth as a carrier and are paired with a separately packaged essence to achieve the delivery of active ingredients. Such products adsorb the essence with the facial mask cloth and then apply it to the skin surface, and utilize the sealing effect of the cloth to promote the penetration of ingredients.

[0003] However, traditional technologies highly rely on the formulation design and storage stability of the essence, which not only increases the production process and packaging costs, but also causes the use process to be cumbersome and there is a risk of ingredient waste because users need to independently prepare the ratio of the facial mask cloth to the liquid essence. In addition, although chitosan is regarded as an ideal active ingredient for facial masks due to its biocompatibility, antibacterial property, and heavy metal adsorption ability, its characteristics of easy aggregation and difficult uniform dispersion in conventional aqueous solutions, as well as the problem of easy degradation during long-term storage, make it difficult for existing processes to achieve efficient loading and stable shaping of chitosan in the facial mask cloth.

[0004] Further research finds that the structure and processing technology of the fiber substrate directly affect the performance of the facial mask cloth. In existing technologies, facial mask fibers mostly use a single material or a simple physical mixture, and the interfacial bonding force between different fibers is insufficient, resulting in problems such as uneven strength and fluctuating liquid absorption in the mixed fiber cloth, thereby affecting the uniform release of active ingredients.

[0005] At the same time, to achieve the fiber loading of chitosan, traditional processes often rely on high-concentration solvents or chemical cross-linking agents. Such methods not only increase the environmental burden, but may also damage the natural active structure of chitosan. More prominently, the "separation of cloth and liquid" design mode of traditional facial masks is difficult to meet the user's requirements for portability and ready-to-use, and the lack of a solvent recovery mechanism during the production process exacerbates resource waste and environmental pollution, which is contrary to the current concept of green manufacturing.

[0006] Therefore, developing a facial mask preparation technology that can achieve stable loading of chitosan, controllable optimization of the fiber structure, and has both high-efficiency skin care and environmental protection properties has become the key direction to break through the industry bottleneck. Summary of the Invention

[0007] The purpose of the present invention is to provide a water-soluble chitosan fiber facial mask and its production process. By optimizing the chitosan dispersion, fiber activation, gradient structure, and negative pressure penetration design, the technical problems of poor dispersion of chitosan in the facial mask substrate, easy degradation of molecules, and uneven loading are systematically solved. At the same time, the synergistic optimization of the rapid solubility of the facial mask and the slow release of active ingredients is achieved.

[0008] The technical solution adopted by the present invention to solve the above technical problems is as follows: In the first aspect, the present invention provides a production process for a water-soluble chitosan mask, which realizes the efficient dispersion of chitosan, the strengthening of the fiber interface, and green manufacturing through the synergistic action of multiple steps. This process method includes the following steps: First, a chitosan raw material with a deacetylation degree of 90%-92% is selected and immersed in an aqueous solution containing 1%-2% sodium dodecyl sulfate (SDS) by mass. It is continuously stirred at a speed of 100-300 revolutions per minute for 2-4 hours at room temperature. The amphiphilic molecular structure of SDS plays a key role in this process: its hydrophobic end (dodecyl chain) adsorbs to the hydrophobic region of the chitosan molecular chain (such as residual acetyl groups) through van der Waals forces, while the hydrophilic end (sulfonic acid group) forms hydrogen bonds with water molecules, significantly reducing the chitosan-water interfacial tension (from 72 mN / m to 35 mN / m).

[0009] This micellization dispersion mechanism reduces the chitosan zeta potential from +35 mV (in a pure water system) to +18 mV, achieving stable dispersion in a near-neutral environment and avoiding the cleavage of β-1,4 glycosidic bonds caused by traditional strong acid dissolution. Subsequently, the pretreated chitosan is separated by filtration or centrifugation and washed with water to remove residual SDS, and finally dried at 40-50 °C for standby. This temperature range can inhibit the thermal degradation of the chitosan molecular chain.

[0010] Traditional chitosan dissolution requires the use of acetic acid (pH < 4), resulting in the degradation of the molecular chain (molecular weight loss > 40%). In contrast, the present invention achieves stable dispersion in a near-neutral (pH = 6.5-7) environment through SDS micellization dispersion, with a molecular weight retention rate > 95% More preferably, Tencel, viscose fiber, or sodium alginate fiber is placed in the reaction chamber of a plasma treatment device. After evacuating to 10-100 Pa, oxygen is introduced (flow rate 50-200 sccm), and it is treated for 2-4 minutes under the action of a radio frequency power supply (13.56 MHz, power 80-120 W). High-energy oxygen ions (O⁺, O2⁺) in the plasma bombard the fiber surface, causing C-C bond cleavage and generating free radicals, which then react with oxygen to form hydroxyl groups (-OH) and carboxyl groups (-COOH). Plasma etching forms micron-scale grooves on the fiber surface, increasing the specific surface area by about 30%, and enhancing the mechanical interlocking force between fibers to 2.3 times that of traditional fibers.

[0011] After this treatment, the hydroxyl density on the fiber surface is ≥5 groups / nm², and the carboxyl density is ≥3 groups / nm² (verified by XPS test). The contact angle decreases from 85° to below 15°, and the surface roughness Ra reaches 1.2 - 1.8 μm (measured by AFM). The introduction of hydroxyl and carboxyl not only enhances the hydrophilicity of the fiber but also provides anchoring sites for the subsequent electrostatic adsorption of chitosan (the combination of NH3⁺ and -COO⁻). Combined with the mechanical interlocking effect generated by surface roughening (the binding energy is increased to 120 nN), the chitosan loading rate is significantly improved.

[0012] Furthermore, the pretreated chitosan and the plasma-activated fibers are mixed in a gradient manner. Specifically, first, the chitosan fibers are dispersed in a 1% - 2% sodium carboxymethylcellulose (CMC) solution for 15 - 20 minutes under high-speed stirring at 1000 - 1500 revolutions per minute. As an anionic dispersant, the molecular chain of CMC is adsorbed on the positively charged chitosan surface through electrostatic attraction, forming an adsorption layer with a thickness of about 15 nm (measured by dynamic light scattering). Through the steric hindrance effect and charge repulsion (the system Zeta potential is stabilized at -25 mV), the sedimentation rate of the chitosan suspension is reduced from 3.2 mm / min to 0.8 mm / min, effectively preventing secondary agglomeration.

[0013] Subsequently, the plasma-treated fibers are slowly added to the suspension and mixed for 30 - 40 minutes under low-speed stirring at 300 - 500 revolutions per minute. The low-speed mixing stage is in the laminar flow region (Reynolds number Re = 200 - 300), avoiding physical damage to the fiber surface caused by high-speed turbulence, and at the same time ensuring that the void fraction between fibers is controlled at 35% ± 2% (tested by mercury intrusion porosimetry), providing a channel for the deep penetration of the subsequent immersion liquid.

[0014] Compared with the traditional blending method that is prone to uneven fiber entanglement, the present invention can effectively optimize the interfacial compatibility through the "dispersion first and then mixing" strategy. The mixing uniformity reaches 92%, and the void fraction between fibers is controlled at 35 ± 2%, providing an ideal channel for subsequent negative pressure penetration.

[0015] After the fiber mixing is completed, nonwoven fabric forming is carried out on the mixed fibers. A multi-stage needling process is adopted: the first-stage needling density is 60 - 80 needles / cm², and the needling depth is 2 - 3 mm to form a preliminary fiber network (fiber orientation degree 0.3); the second-stage needling density is 100 - 120 needles / cm², and the depth is 3 - 4 mm to further compact the fibers and increase the orientation degree to 0.65 (calculated by XRD), and the tensile strength is increased from 4.2 N / cm to 8.5 N / cm.

[0016] Strengthened structure through double-nozzle hydroentangling technology: The front nozzle sprays water jets at a pressure of 15 - 20 MPa and an angle of 30 - 40°, stretching the surface fibers and forming a pore structure with a pore size of 50 - 80 μm; the rear nozzle tangles the deep layers of the fibers at a pressure of 20 - 25 MPa and an angle of 40 - 50°, forming an inner layer pore size of 10 - 30 μm, achieving a gradient pore structure (50 - 80 μm on the surface, 10 - 30 μm on the inner layer). The skin-contact surface roughness (Sa = 8.6 μm) is reduced by 40% compared to the traditional process, enhancing the application comfort.

[0017] Finally, 5% - 8% of low-melting-point polyester fibers (melting point 110 - 130 °C) are added. After melting under a pressure of 0.3 - 0.5 MPa, they penetrate to the fiber cross-points and form "rivet-type" bonding points (diameter 5 - 8 μm) after cooling. The fiber peel strength is increased from 0.8 N / cm to 2.4 N / cm.

[0018] Compared with the wet strength of only 2.1 N / cm for non-woven fabrics produced by traditional single hydroentangling process, the wet strength of the present invention reaches 4.2 N / cm (far exceeding the industry standard of 2.5 N / cm) through triple enhancement of needling - hydroentangling - hot melting, and the thickness uniformity is better than the industry standard.

[0019] On this basis, the formed mixed fiber substrate is subjected to negative pressure soaking treatment. The soaking solution is a mixed solution of acid and ethanol containing chitosan, where the mass ratio of chitosan to the mixed solution is 1:0.2 - 1:2. Further, the acid in the mixed solution contains at least one of citric acid, malic acid, lactic acid, succinic acid, lactobionic acid, azelaic acid, and the mass percentage of ethanol in the mixed solution is 10 - 15%. The acid in the mixed solution can be compounded by citric acid and malic acid at a mass ratio of 2:1 (total concentration 2% - 5%), adjusting the pH to 3.5 - 4.0 to form a buffer system to avoid the breakage of chitosan molecular chains caused by local over-acidity (pH < 3).

[0020] Before soaking, the mixed fiber substrate is first immersed in a 1% - 2% sodium hydroxide solution (40 - 50 °C) for 1 - 2 hours for pretreatment to remove surface impurities and activate the hydroxyl sites, and then transferred to the soaking solution preheated to 30 - 35 °C, and soaked for 3 - 5 hours in a negative pressure environment of -0.05 ~ -0.08 MPa. The negative pressure condition promotes the discharge of gas in the fiber pores (the porosity increases from 65% to 82%), and the solution penetrates to the fiber core layer at a rate of 0.35 mm / s through capillary action (only 0.12 mm / s under normal pressure), and the chitosan loading depth covers 90% of the fiber radius. After soaking, it is rinsed with water at 20 - 25 °C to remove the unadsorbed components to ensure the uniformity of chitosan distribution.

[0021] Finally, ethanol was removed by vacuum distillation: the soaked fibers were placed in a recovery device with a vacuum degree of -0.09 to -0.095 MPa, and gradually heated to 40 - 50 °C, so that the boiling point of ethanol decreased from 78 °C to 38 °C, the evaporation rate reached 1.2 L / (m²·h), and the ethanol recovery rate was ≥92%. Combined with a preservative-free formula (relying on the antibacterial property of chitosan), the production wastewater per ten thousand mask fabrics decreased from 500 L in the traditional process to 12 L, and the COD value was <50 mg / L, which could be directly recycled.

[0022] After distillation, the fibers were dried at 40 - 50 °C and a vacuum degree of 0.08 - 0.09 MPa for 2 - 3 hours, and the moisture diffusion coefficient D = 2.1×10⁻ 9 m² / s, avoiding the fiber shrinkage stress (<0.5 MPa) caused by rapid drying, and finally obtaining a water-soluble chitosan mask with a chitosan content of ≥10%, a molecular weight retention rate of ≥95%, and a change in deacetylation degree of ≤1%.

[0023] On the second aspect, the present invention also provides a water-soluble chitosan mask, which is prepared by the production process of the above-mentioned water-soluble chitosan mask, and this mask has the following characteristics: The surface layer pore size is 50 - 80 μm (water locking rate ≥95%), and the inner layer pore size is 10 - 30 μm (sustained release efficiency 65%); Rivet-like hot melt bonding points with a diameter of 5 - 8 μm are formed at the fiber intersection points (observed by SEM); The chitosan molecular weight distribution index PDI ≤ 1.3 (tested by GPC), and the change rate of deacetylation degree ≤ 1% (analyzed by FTIR); The wet strength is ≥4.2 N / cm, it completely dissolves within 30 seconds, and the antibacterial rate is ≥99%.

[0024] Through the systematic synergy of the above process, the present invention has achieved breakthroughs in the dispersion stability of chitosan, the fiber interface bonding strength, environmental protection, and product performance, providing new ideas for the application of chitosan.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) Through the quadruple effects of SDS micellization, plasma activation, CMC dispersant, and negative pressure penetration, the industry problems of difficult dispersion and easy agglomeration of chitosan are overcome, and the loading rate and uniformity reach the international leading level.

[0026] (2) The multi-stage needling - hydroentangling - hot melt process constructs the gradient pore size and mechanical properties of the nonwoven fabric, realizes the "demand - driven release" of active ingredients (initial release rate 35%, later 65%), which is more in line with the skin absorption kinetics than the linear release mode of traditional masks (initial 70%, later 30%).

[0027] Retention and uniform loading of highly active chitosan (1) In the present invention, SDS is micellized and dispersed in a near-neutral environment to block the acid degradation path of chitosan molecular chains, increasing the molecular weight retention rate from <60% in the traditional process to ≥95%; the carboxyl density on the surface of the plasma-activated fiber is increased to ≥3 groups / nm², and through the dual actions of electrostatic adsorption and mechanical interlocking, the chitosan loading rate is increased from 8 - 10% to 15%, and the distribution uniformity (RSD ≤ 7%) is significantly better than that of the traditional process (RSD > 20%).

[0028] (2) The gradient needling - hydroentangling process in the present invention constructs a bionic structure with a dense surface layer (the water locking rate is increased by 40%) and a loose inner layer (the sustained release efficiency reaches 65%). Combining with the hot melt rivet bonding points, the wet strength of the mask fabric is increased from 2.1 N / cm to 4.2 N / cm, and it can be completely dissolved within 30 seconds. The fitting degree of the patch (roughness Sa = 8.6 μm) is reduced by 40% compared with the traditional product.

[0029] (3) The present invention uses plasma dry modification to replace the chemical grafting process, achieving basically zero monomer residue; the ethanol recovery rate ≥92% combined with the preservative-free formula reduces the COD value of the production wastewater from 2000 mg / L to <50 mg / L.

[0030] (4) The synergistic effect of low-temperature vacuum drying and the integrity of chitosan molecular weight in the present invention makes the antibacterial rate (against Escherichia coli and Staphylococcus aureus) stable at ≥99%, far exceeding 80% of the traditional process, and there is no irritation of chemical preservatives.

[0031] In summary, the present invention systematically solves the technical problems of poor solubility, molecular degradation, uneven loading and high environmental load of chitosan through the process coupling of micellization dispersion - plasma activation - gradient structure design - negative pressure penetration, breaks through the performance bottleneck of traditional mask substrates, and has high activity, strong mechanics, low irritation and environmental friendliness.

[0032] The present invention will be explained and described in detail below in conjunction with the drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the overall process flow of the production process of the water-soluble chitosan mask shown in the embodiment of the present invention; Figure 2 It is a bar chart of the wet strength of the chitosan masks prepared in the embodiments and comparative examples of the present invention; Figure 3 It is a bar chart of the dissolution time of the chitosan masks prepared in the embodiments and comparative examples of the present invention; Figure 4 It is a line chart of the chitosan content of the chitosan masks prepared in the embodiments and comparative examples of the present invention; Figure 5It is a line graph of the molecular weight retention rate of the chitosan facial masks prepared in the embodiments and comparative examples of the present invention; Figure 6 It is a line graph of the solution penetration rate of the chitosan facial masks prepared in the embodiments and comparative examples of the present invention. Detailed implementation manners

[0034] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in different forms and is not limited to the embodiments described in the text. On the contrary, these embodiments are provided to make the disclosed content of the present invention more thorough and comprehensive.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0036] Example 1: The embodiment of the present invention provides a production process of a water-soluble chitosan facial mask, including the following steps: (1) Raw material treatment: Mix and disperse chitosan with a surfactant solution, and perform plasma treatment on the fiber material. Specifically, in this embodiment, chitosan with a deacetylation degree of 90% is selected, and it is mixed with a 1% sodium dodecyl sulfate (SDS) solution in a mass ratio of 1:10 and continuously stirred at a stirring speed of 200 rpm for 3 hours to fully disperse chitosan in the SDS solution. At the same time, prepare tencel fiber and place it in an oxygen plasma treatment device to treat it for 3 minutes under the conditions of an oxygen flow rate of 100 sccm and a power of 100 W to increase the active groups on the fiber surface.

[0037] (2) Mixing process: Gradually mix the pretreated chitosan with the fiber material in the presence of a dispersant. Specifically, in this embodiment, the chitosan treated with SDS is dispersed in a 2% sodium carboxymethyl cellulose (CMC) solution at a high speed of 1200 rpm for 18 minutes to further uniformly disperse chitosan. Subsequently, the tencel fiber treated with plasma is added and mixed at a low speed of 400 rpm for 35 minutes to allow chitosan to fully adhere to the fiber surface.

[0038] (3)Nonwoven fabric forming: A fiber substrate is prepared through needling, hydroentangling, and heat melt bonding processes. In this embodiment, a two-stage needling process is adopted. The needling density of the first stage is 70 needles / cm², and the needling depth is 2.5 mm; the needling density of the second stage is increased to 110 needles / cm², and the needling depth is 3.5 mm. Through needling, the fibers are entangled with each other for preliminary forming. Then, double-nozzle hydroentangling is carried out. The pressure of the front nozzle is 18 MPa, and the spraying angle is 35°; the pressure of the rear nozzle is 23 MPa, and the spraying angle is 45°, further strengthening the fiber structure. After that, low-melting-point polyester fibers with a mass fraction of 6% are added, and heat melt bonding is carried out at 120 °C and a pressure of 0.4 MPa to make the fiber combination more firm.

[0039] (4)Soaking process: The mixed fiber substrate is immersed in a mixed solution of acid and ethanol containing chitosan under negative pressure conditions, where the mass ratio of chitosan to the mixed solution is 1:0.2 - 1:2. Specifically, in this embodiment, a mixed solution of citric acid - malic acid (the mass ratio of the two is 2:1) is prepared, and its pH value is adjusted to 3.8. The formed nonwoven fabric is put into this solution, and the mass ratio of chitosan to the solution is 1:1. It is soaked for 4 hours under a negative pressure of -0.07 MPa and at a temperature of 30 °C to make chitosan better penetrate into the fiber interior.

[0040] (5)Post-treatment: Vacuum distillation is carried out under a vacuum degree of -0.092 MPa and a temperature of 45 °C to recover ethanol. Then, drying is carried out under a vacuum condition of 45 °C and 0.085 MPa to remove excess moisture, obtaining the final facial mask product.

[0041] Comparison table of the performance data of the facial masks prepared in Examples 1 - 6 and Comparative Examples 1 - 3

[0042] In Examples 1 - 6 of the present invention, through a triple enhancement process of needling - hydroentangling - heat melt (such as 70 → 110 needles / cm² needling + double-nozzle hydroentangling + 6% low-melting-point polyester fibers in Example 1), rivet - type bonding points (with a diameter of 5 - 8 μm) are formed, significantly enhancing the bonding force between fibers. The wet strength is increased by more than 100% compared with the traditional process (2.1 N / cm in Comparative Example 1).

[0043] Dissolution time (24 - 30 seconds): The synergistic effect of the gradient pore size structure (surface layer 50 - 80 μm + inner layer 10 - 30 μm) and the plasma-activated fibers (hydroxyl density ≥ 5 groups / nm²) accelerates the solution penetration (such as the penetration rate of 0.48 mm / s in Example 6), and the dissolution time is shortened by 50% compared with Comparative Example 1 (60 seconds).

[0044] Chitosan loading uniformity (RSD ≤ 6.8%): SDS micellization dispersion (retaining 95% molecular weight in near-neutral environment) + CMC steric hindrance effect + negative pressure penetration (-0.05~-0.08 MPa), enabling chitosan to be evenly distributed in the fiber core layer, and the loading uniformity is improved by 76% compared to Comparative Example 1 (RSD = 22.1%).

[0045] Environmental friendliness (ethanol recovery rate ≥ 92%): Combining reduced pressure distillation (-0.09~-0.095 MPa) with vacuum drying, the ethanol recovery rate is increased by 33% compared to Comparative Example 1 (70%), and the wastewater COD < 50 mg / L can be directly recycled.

[0046] In Comparative Example 1, traditional single fibers were used. The untreated fibers resulted in a chitosan loading rate of only 8.3%, and the lack of a gradient structure extended the dissolution time to 60 seconds, with a wet strength of only 2.1 N / cm.

[0047] In Comparative Example 2, the fibers were not activated, resulting in insufficient surface hydroxyl density (<2 groups / nm²), low chitosan adsorption (8.5%), and a single dispersant (only PEG) leading to poor loading uniformity (RSD = 18.5%).

[0048] In Comparative Example 3, the lack of needling reinforcement led to a low fiber orientation degree (0.3), with a wet strength of only 3.5 N / cm; the absence of a gradient pore structure resulted in a decrease in the penetration rate (0.22 mm / s), and the dissolution time was extended to 40 seconds.

[0049] In summary, the examples of the present invention, through plasma activation of fibers (enhancing adsorption sites), gradient mixing process (optimizing dispersibility), multi-process synergistic enhancement (needling - hydroentangling - hot melting), and negative pressure penetration (promoting uniform chitosan loading), are significantly superior to traditional processes in terms of mechanical properties, dissolution efficiency, activity retention, and environmental friendliness.

[0050] Example 2: The examples of the present invention provide a production process for a water-soluble chitosan facial mask, including the following steps: (1) Raw material treatment: Mix and disperse chitosan with a surfactant solution, and perform plasma treatment on the fiber material. Specifically, in this example, chitosan with a deacetylation degree of 92% is selected and mixed with a 2% SDS solution at a ratio of 1:10, and stirred at a stirring speed of 300 rpm for 2 hours. The Tencel fiber is subjected to oxygen plasma treatment with an oxygen flow rate of 200 sccm, a power of 120 W, and a treatment time of 2 minutes.

[0051] (2) Mixing process: Gradually mix the pretreated chitosan and fiber materials in the presence of a dispersant. Specifically, in this example, the treated chitosan is dispersed in a 2% CMC solution at a high speed of 1500 rpm for 20 minutes, and then the plasma-treated fibers are added and mixed at a low speed of 500 rpm for 30 minutes.

[0052] (3) Non-woven fabric forming: Prepare the fiber substrate through needling, hydroentangling, and heat melt bonding processes. In this example, a two-stage needling process is used. The first-stage needling density is 80 needles / cm² and the depth is 2.5 mm; the second-stage needling density is 120 needles / cm² and the depth is 3.5 mm. Then, double-nozzle hydroentangling is carried out. The pressure of the front nozzle is 20 MPa and the angle is 35°; the pressure of the rear nozzle is 25 MPa and the angle is 45°. 6% of low-melting-point polyester fibers are added and heat melt bonded at 130 °C and 0.5 MPa.

[0053] (4) Immersion process: Immerse the mixed fiber substrate in a mixed solution of acid and ethanol containing chitosan under negative pressure, where the mass ratio of chitosan to the mixed solution is 1:0.2 - 1:2. Specifically, in this example, a lactic acid solution is prepared, and the formed non-woven fabric is put into it. The mass ratio of chitosan to the solution is 1:1, and it is immersed at -0.08 MPa negative pressure and 35 °C for 5 hours.

[0054] (5) Post-treatment: Recover ethanol by vacuum distillation at -0.095 MPa and 50 °C, and dry it under vacuum conditions of 50 °C and 0.09 MPa.

[0055] Example 3: The embodiment of the present invention provides a production process for a water-soluble chitosan facial mask, including the following steps: (1) Raw material treatment: Mix and disperse chitosan with a surfactant solution, and perform plasma treatment on the fiber materials. Specifically, in this example, chitosan with a deacetylation degree of 90% is mixed with a 1% SDS solution at a ratio of 1:10 and stirred at 200 rpm for 3 hours. The fiber materials are selected as a 1:1 mixture of Tencel and sodium alginate fibers, and the mixed fibers are subjected to oxygen plasma treatment with an oxygen flow rate of 100 sccm, a power of 100 W, and treated for 3 minutes.

[0056] (2) Mixing process: Gradually mix the pretreated chitosan and fiber materials in the presence of a dispersant. Specifically, in this example, chitosan is dispersed in a 2% CMC solution at 1200 rpm for 18 minutes, and the treated mixed fibers are added and mixed at 400 rpm for 35 minutes.

[0057] (3) Non-woven fabric forming: Prepare the fiber substrate through needling, hydroentangling and hot melt bonding processes. In this embodiment, the needling process is the same as that in Example 1, and the hydroentangling process is also the same as that in Example 1. Add 8% of low melting point polyester fiber and conduct hot melt bonding at 130°C and 0.4 MPa.

[0058] (4) Immersion process: Immerse the mixed fiber substrate in a mixed solution of acid and ethanol containing chitosan under negative pressure conditions, where the mass ratio of chitosan to the mixed solution is 1:0.2 - 1:2. Specifically, in this embodiment, a citric acid - malic acid (2:1) mixed solution with a pH of 3.8 is used, the mass ratio of chitosan to the solution is 1:1, and immerse for 4 hours at -0.07 MPa and 30°C.

[0059] (5) Post-treatment: Recover ethanol by vacuum distillation at -0.092 MPa and 45°C, and conduct vacuum drying at 45°C and 0.085 MPa.

[0060] Example 4: The embodiment of the present invention provides a production process for a water-soluble chitosan facial mask, including the following steps: (1) Raw material treatment: Mix and disperse chitosan with a surfactant solution, and conduct plasma treatment on the fiber material. Specifically, in this embodiment, chitosan with a deacetylation degree of 92% is selected, mixed with a 2% SDS solution at a ratio of 1:10, and stirred at 300 rpm for 2 hours. The fiber material is viscose fiber, and oxygen plasma treatment is conducted with an oxygen flow rate of 200 sccm and a power of 120 W for 2 minutes.

[0061] (2) Mixing process: Gradiently mix the pretreated chitosan and fiber material in the presence of a dispersant. Specifically, in this embodiment, chitosan and a 2% CMC solution are dispersed at 1500 rpm for 20 minutes, then the treated viscose fiber is added and mixed at 500 rpm for 30 minutes.

[0062] (3) Non-woven fabric forming: Prepare the fiber substrate through needling, hydroentangling and hot melt bonding processes. In this embodiment, a two-stage needling process is adopted. The first stage is 70 needles / cm² with a depth of 2.5 mm; the second stage is 110 needles / cm² with a depth of 3.5 mm. Then, double-nozzle hydroentangling is carried out. The front nozzle is at 18 MPa and 35°; the rear nozzle is at 23 MPa and 45°. Add 5% of low melting point polyester fiber and conduct hot melt bonding at 110°C and 0.3 MPa.

[0063] (4) Immersion process: Immerse the mixed fiber substrate in a mixed solution of acid and ethanol containing chitosan under negative pressure conditions, where the mass ratio of chitosan to the mixed solution is 1:0.2 - 1:2. Specifically, in this embodiment, a lactic acid solution is prepared, the mass ratio of chitosan to the solution is 1:1, and immerse for 5 hours at -0.08 MPa and 35°C.

[0064] (5) Post-treatment: Ethanol was recovered by vacuum distillation at -0.095 MPa and 50 °C, and then vacuum dried at 50 °C and 0.09 MPa.

[0065] Example 5: The present invention provides a production process for a water-soluble chitosan mask, comprising the following steps: (1) Raw material treatment: Chitosan was mixed and dispersed with a surfactant solution, and the fibrous material was subjected to plasma treatment. Specifically, in this example, chitosan with a deacetylation degree of 90% was mixed with a 1% SDS solution at a ratio of 1:10 and stirred at 200 rpm for 3 hours. The Tencel fiber was subjected to plasma treatment under the same conditions as in Example 1.

[0066] The mixing process, non-woven fabric forming and post-treatment steps were all the same as in Example 1.

[0067] In the soaking process, a citric acid - malic acid (2:1) mixed solution with a pH of 3.8 was prepared, and the mass ratio of chitosan to the solution was 1:0.2. The soaking was carried out at -0.07 MPa and 30 °C for 3 hours.

[0068] Example 6: The present invention provides a production process for a water-soluble chitosan mask, comprising the following steps: (1) Raw material treatment: Chitosan was mixed and dispersed with a surfactant solution, and the fibrous material was subjected to plasma treatment. Specifically, in this example, chitosan with a deacetylation degree of 92% was mixed with a 2% SDS solution at a ratio of 1:10 and stirred at 300 rpm for 2 hours. The Tencel fiber was subjected to plasma treatment with an oxygen flow rate of 200 sccm and a power of 120 W for 2 minutes.

[0069] (2) Mixing process: The pretreated chitosan and fibrous material were gradually mixed in the presence of a dispersant. Specifically, in this example, the chitosan treated with SDS was dispersed in a 2% CMC solution at 1500 rpm for 20 minutes, and then the treated fiber was added and mixed at 500 rpm for 40 minutes.

[0070] In this example, the non-woven fabric forming and post-treatment steps were the same as in Example 1.

[0071] In the soaking process of this example, a lactic acid solution was prepared, and the mass ratio of chitosan to the solution was 1:2. The soaking was carried out at -0.08 MPa and 35 °C for 5 hours.

[0072] Comparative Example 1: In this comparative example, a single Tencel fiber was selected as the raw material for the mask substrate without any pretreatment. A conventional needle punching process was used to make the Tencel fiber into a mask substrate. A chitosan solution was prepared, and the formed mask substrate was immersed in the solution. The immersion time and conditions were 4 hours at normal temperature and pressure. The immersed mask substrate was air-dried at normal temperature to obtain the final product.

[0073] Comparative Example 2: In this comparative example, Tencel fibers and sodium alginate fibers were prepared and mixed as raw materials for the mask substrate in a mass ratio of 1:1, without pre-treatment such as plasma treatment. The mixed fibers were made into a mask substrate by conventional needling and hydroentangling processes. A chitosan solution was prepared, and the formed mask substrate was immersed in the solution for 4 hours at normal temperature and pressure. The immersed mask substrate was air-dried at normal temperature.

[0074] Comparative Example 3: In this comparative example, chitosan with a deacetylation degree of 90% was selected and mixed with a 1% SDS solution in a mass ratio of 1:10, and continuously stirred at a stirring speed of 200 rpm for 3 hours. The Tencel fibers were treated with oxygen plasma, with an oxygen flow rate of 100 sccm and a power of 100 W, for 3 minutes. The chitosan treated with SDS was dispersed with a 2% CMC solution at a high speed of 1200 rpm for 18 minutes, and then the Tencel fibers treated with plasma were added and mixed at a low speed of 400 rpm for 35 minutes.

[0075] In this comparative example, only a single hydroentangling process was used, with a hydroentangling pressure of 20 MPa and a spraying angle of 45° to form the fibers. Then, 6% low-melting-point polyester fibers were added and hot melt bonding was carried out at 120°C and a pressure of 0.4 MPa.

[0076] In the immersion process of this comparative example, a mixed solution of citric acid - malic acid (mass ratio of 2:1) was prepared, and its pH value was adjusted to 3.8. The formed non-woven fabric was put into the solution, and the mass ratio of chitosan to the solution was 1:1. It was immersed for 4 hours under a negative pressure of -0.07 MPa and at 30°C.

[0077] Vacuum distillation was carried out under a vacuum degree of -0.092 MPa and a temperature of 45°C to recover ethanol. Then, drying was carried out under a vacuum condition of 45°C and 0.085 MPa to obtain the final product.

[0078] Any numerical value cited in this text includes all values from the lower limit value to the upper limit value increasing in increments of one unit, provided that there is an interval of at least two units between any lower value and any higher value. For example, if the value of the number of components or process variables (such as temperature, pressure, time, etc.) is stated as ranging from 1 to 90, preferably from 20 to 80, and more preferably from 30 to 70, the intention is to illustrate that values such as 15 to 85, 22 to 68, 43 to 51, 30 to 32, etc. are also explicitly listed in this specification. For values less than 1, a unit is appropriately considered to be 0.0001, 0.001, 0.01, 0.1. These are merely examples of what is intended to be clearly expressed, and it can be considered that all possible combinations of the numerical values listed between the lowest value and the highest value are explicitly stated in this specification in a similar manner.

[0079] Unless otherwise specified, all ranges include the endpoints and all numbers between the endpoints. The term "about" or "approximate" used in connection with a range is applicable to both endpoints of the range. Thus, "about 20 to 30" is intended to cover "about 20 to about 30", including at least the specified endpoints.

[0080] It should be understood that the foregoing description is illustrative rather than restrictive. Many embodiments and many applications other than the examples provided will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of the present teachings should not be determined with reference to the above description, but rather should be determined with reference to the appended claims and the full scope of equivalents to which such claims are entitled. For the sake of completeness, all articles and references, including patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein from the foregoing claims is not a waiver of that subject matter, nor should it be assumed that the inventors did not consider that subject matter to be part of the disclosed inventive subject matter.

[0081] The present invention has been described above by way of example in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited by the above methods. As long as such non-substantial improvements are made by adopting the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A production process of a water-soluble chitosan facial mask, characterized in that, It includes the following steps: (1) Raw material treatment: Mix and disperse chitosan with a surfactant solution, and perform plasma treatment on the fiber material; (2) Mixing process: Gradiently mix the pretreated chitosan and fiber material in the presence of a dispersant; (3) Non-woven fabric forming: Prepare a fiber substrate through needling, hydroentangling, and hot melt bonding processes; (4) Immersion process: Immerse the mixed fiber substrate in a mixed solution of acid and ethanol containing chitosan under negative pressure, where the mass ratio of chitosan to the mixed solution is 1:0.2 - 1:2; (5) Post-treatment: Remove ethanol by vacuum distillation and recover it, and obtain a water-soluble chitosan facial mask with a chitosan content ≥ 10% and a molecular weight retention rate ≥ 95% after drying.

2. The production process of the water-soluble chitosan facial mask according to claim 1, characterized in that, In step (1): The surfactant is sodium dodecyl sulfate, with a mass concentration of 1 - 2%, a stirring speed of 100 - 300 rpm, and a treatment time of 2 - 4 hours; And / or, the plasma treatment parameters include: an oxygen flow rate of 50 - 200 sccm, a radio frequency power of 80 - 120 W, and a treatment time of 2 - 4 minutes.

3. The production process of the water-soluble chitosan facial mask according to claim 2, wherein The fiber material includes at least one of tencel, viscose fiber, and sodium alginate fiber; And / or, after plasma treatment, the hydroxyl density on the fiber surface ≥ 5 groups / nm², the carboxyl density ≥ 3 groups / nm², and the surface roughness Ra is 1.2 - 1.8 μm.

4. The production process of the water-soluble chitosan facial mask according to claim 1, characterized in that, In step (2): The dispersant is sodium carboxymethyl cellulose, with a mass concentration of 1 - 2%; And / or, the gradient mixing includes: first dispersing chitosan fibers at a high speed of 1000 - 1500 rpm for 15 - 20 minutes, and then mixing other fibers at a low speed of 300 - 500 rpm for 30 - 40 minutes.

5. The production process of the water-soluble chitosan facial mask according to claim 1, characterized in that In step (3): The needling process includes two-stage needling, where the first-stage needling density is 60 - 80 needles / cm² and the depth is 2 - 3 mm, and the second-stage needling density is 100 - 120 needles / cm² and the depth is 3 - 4 mm; And / or, the hydroentangling process uses a double nozzle, with the pressure of the front nozzle being 15 - 20 MPa and the nozzle angle being 30 - 40°, and the pressure of the rear nozzle being 20 - 25 MPa and the nozzle angle being 40 - 50°; And / or, the hot melt bonding fiber is a low melting point polyester fiber, with an addition amount of 5 - 8%, a hot melt temperature of 110 - 130 °C, and a pressure of 0.3 - 0.5 MPa.

6. The production process of the water-soluble chitosan facial mask according to claim 1, characterized in that, In step (4): The acid in the mixed solution includes at least one of citric acid, malic acid, lactic acid, succinic acid, lactobionic acid, and azelaic acid, and the mass percentage of ethanol in the mixed solution is 10 - 15%; And / or, the negative pressure condition is -0.05 ~ -0.08 MPa, the immersion temperature is 30 - 35 °C, and the immersion time is 3 - 5 hours.

7. The production process of the water-soluble chitosan facial mask according to claim 6, characterized in that, The pH value of the composite acid solution is 3.5 - 4.0, the dissolution activation energy of chitosan ≤ 38 kJ / mol, and the solution penetration rate ≥ 0.35 mm / s.

8. The production process of the water-soluble chitosan facial mask according to claim 1, characterized in that, In step (5): Vacuum distillation maintains a vacuum environment, with a vacuum degree of -0.09 ~ -0.095 MPa, a temperature of 40 - 50 °C, and an ethanol recovery rate ≥ 92%; The vacuum drying conditions are 40 - 50°C and a vacuum degree of 0.08 - 0.09 MPa. After drying, the chitosan content is ≥15%, and the molecular weight retention rate is ≥95%.

9. The production process of the water-soluble chitosan facial mask according to claim 1, characterized in that, The properties of the final water-soluble chitosan facial mask meet the following conditions: The wet strength is ≥4.2 N / cm, it completely dissolves within 30 seconds, the RSD of the chitosan loading uniformity is ≤7%, and the antibacterial rate is ≥99%.

10. A water-soluble chitosan facial mask cloth, characterized in that, Prepared by the production process of the water-soluble chitosan facial mask according to any one of claims 1 - 9, its microstructure includes: The surface layer pore size is 50 - 80 μm, and the inner layer pore size is 10 - 30 μm; Rivet-type hot melt bonding points with a diameter of 5 - 8 μm are formed at the fiber bonding points; The chitosan molecular weight distribution index PDI is ≤1.3, and the degree of change in deacetylation is ≤1%.

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