Antibacterial fabric preparation method based on physical vapor deposition

Abstract

The invention belongs to the technical field of functional textile processing, and particularly relates to a method for forming metal or compound particles, networks or film layers thereof on the surface of a fabric by adopting a physical vapor deposition technology so as to realize antibacterial performance. The method is realized through the following steps: pretreating a fabric; particles, networks or film layers with the thickness ranging from 0.5 nm to 1 [mu] m are formed on the surface of the fabric through physical vapor deposition, the particles, networks or film layers comprise at least one metal of silver, titanium and copper or at least one metal of oxides and nitrides of the metal, and the coverage area of the particles, networks or film layers observed under a microscope accounts for 0.1% or above of the total observable surface area of the fibers; and finally finishing the fabric. The traditional concept that a nanoscale film layer needs to completely cover the fiber surface to inhibit bacteria is broken through, and the fabric is still endowed with good antibacterial performance under the low coverage rate, so that the design complexity of a production system of a physical vapor deposition process is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional textile processing, and particularly relates to a method for forming metal or its compound particles, networks or film layers on the fabric surface by physical vapor deposition technology to achieve antibacterial performance. Background Art

[0002] In the prior art, methods for endowing fabrics with antibacterial properties include chemical impregnation method, nanomaterial coating method, electrochemical deposition method, etc. Although these traditional methods are widely used, each technology has significant defects. For example, the chemical impregnation method requires the use of a large amount of solutions containing heavy metal ions (such as silver ions) or organic solvents. The wastewater generated during the production process is difficult to treat, easily causing water pollution, and the residual chemical substances may cause irritation to human skin; the antibacterial layer formed by the coating method has a low bonding strength with the fiber surface and is easily detached during mechanical friction or repeated washing; the electrochemical deposition method is generally applicable to conductive fibers (such as silver-plated fibers, carbon fibers), while natural fibers (cotton, linen) or some synthetic fibers (polyester, nylon) need to be pre-coated with a conductive layer, increasing the process complexity. In addition, during its production process, the electrolyte contains heavy metal ions, the waste liquid treatment cost is high, and the electro-deposition process consumes a large amount of energy.

[0003] In recent years, due to its characteristics such as pollution-free, high adhesion and process controllability, physical vapor deposition technology has gradually been introduced into the field of textile functionalization. For example, metal or oxide layers are deposited on the fabric surface by magnetron sputtering to achieve coloring, conductivity or antibacterial functions. In the field of using physical vapor deposition technology to deposit metal element-containing substances such as silver, copper, titanium oxide and lanthanide elements on the fabric surface to achieve antibacterial performance of fabrics, there is a common cognitive limitation: it is considered that effective bacteriostasis can only be achieved when the antibacterial material completely covers the fiber surface in the form of a continuous and uniform nanoscale film layer (such as a thickness less than 10 nanometers). This view has led to the complication of process design and restricted the wide application of physical vapor deposition technology in the production of antibacterial fabrics.

[0004] In view of the above problems, the present invention proposes an innovative technical solution to form continuous or discontinuous metal and its compound particles, networks or film layers on the fabric surface by physical vapor deposition technology, breaking through the dependence of traditional processes on uniform nanoscale coverage, and achieving efficient, low-cost and durable broad-spectrum antibacterial performance of fabrics. The core of the present invention lies in verifying the following scientific phenomenon: even if silver, titanium, copper and their compounds are partially attached to the fiber surface in a discontinuous form, they can still significantly inhibit the growth of microorganisms through contact sterilization, ion release or photocatalysis. Its antibacterial effect is closely related to the coverage area and distribution pattern, rather than simply relying on nanoscale continuous film layer coverage. Summary of the Invention

[0005] The present invention provides a method for achieving antibacterial performance of fabrics through physical vapor deposition. The core lies in forming particles, networks or film layers of metals or metal compounds on the surface of fabric fibers through physical vapor deposition technology.

[0006] Furthermore, in the present invention, particles, networks or film layers are deposited on the fabric surface through physical vapor deposition. The particles, networks or film layers are at least one metal among silver, titanium, copper with a thickness of 0.5 nm to 1 μm, or at least one of their oxides or nitrides. Under a microscope, the observable coverage area of the plated particles, networks or film layers on the surface of the fibers constituting the fabric accounts for more than 0.1% of the total observable surface area of the fibers.

[0007] Further, when the thickness of the particles, networks or film layers is greater than or equal to 0.5 nm and less than 5 nm, the observable coverage area of the plated particles, networks or film layers on the surface of the fibers constituting the fabric under a microscope should be more than 1%; when the thickness of the particles, networks or film layers is greater than or equal to 5 nm and less than 1 μm, the observable coverage area of the plated particles, networks or film layers on the surface of the fibers constituting the fabric under a microscope should be more than 0.1%; when there are parts where the thickness of the particles, networks or film layers is greater than or equal to 0.5 nm and less than 5 nm, as well as greater than or equal to 5 nm and less than 1 μm, the observable coverage area of the plated particles, networks or film layers on the surface of the fibers constituting the fabric under a microscope should be greater than 1%.

[0008] The method for preparing an antibacterial fabric based on physical vapor deposition described in the present invention specifically includes the following steps:

[0009] The first step is fabric pretreatment.

[0010] Place the fabric in a cleaning solution and remove the attached grease, dust and other contaminants through ultrasonic oscillation. After cleaning, the fabric is dried to remove the residual moisture and then fixed on the loading mechanism of the physical vapor deposition equipment.

[0011] Furthermore, the cleaning solution can be selected from deionized water, ethanol or other environmentally friendly solvents.

[0012] Furthermore, for the drying treatment, according to the fabric material and production requirements, mechanical drying, infrared drying, heat conduction drying or other drying methods can be selected.

[0013] The second step is vacuum deposition.

[0014] For the method for preparing an antibacterial fabric based on physical vapor deposition described in the present invention, according to different fabric materials and production requirements, a reasonable vacuum deposition method is selected, including but not limited to vacuum evaporation plating, vacuum sputtering plating, and vacuum ion plating.

[0015] Furthermore, the target used for deposition is at least one of silver, titanium, copper, their oxides, and nitrides.

[0016] Furthermore, when depositing oxides and nitrides on the fabric surface, it can be achieved by selecting the corresponding target materials of oxides and nitrides for deposition, or by introducing reactive gases (such as oxygen, nitrogen) to in-situ generate metal oxides (such as titanium dioxide, silver oxide) or nitrides during the deposition process, or by using both of the above methods.

[0017] Preferably, by adjusting the deposition parameters (such as power, gas flow rate, deposition time, the width between the target and the deposited fabric, fabric temperature), the thickness, distribution density, and morphology of the particles, network, or film layer can be controlled, so as to achieve partial coverage of the fiber surface.

[0018] Preferably, multiple chambers are designed for multi-layer deposition of the fabric, or for depositing various target materials mentioned in the present invention.

[0019] The third step is fabric finishing.

[0020] After reasonable vacuum deposition, the processed fabric is sorted and stored through a storage device.

[0021] The method for preparing an antibacterial fabric based on physical vapor deposition according to the present invention has the following deposition characteristic controls:

[0022] Regarding the thickness range, the thickness of the particles, network, or film layer can be flexibly adjusted from extremely thin (close to a single atomic layer) to relatively thick (visible micron level to the naked eye) to meet the requirements of different application scenarios.

[0023] Regarding the coverage area: By optimizing the process parameters, the coverage area of the particles, network, or film layer on the fiber surface reaches a certain proportion. For example, when depositing a relatively thin film layer, the coverage area should be appropriately increased by controlling the parameters; while when depositing a relatively thick film layer, a moderate reduction in the coverage area is allowed, but the minimum antibacterial threshold still needs to be met.

[0024] Morphology diversity: The deposited layer can present various forms such as island-like films, dispersed particles, nanorods, or nano-scale clusters, and the specific morphology is jointly determined by the deposition conditions and material properties.

[0025] The method for preparing an antibacterial fabric based on physical vapor deposition according to the present invention has the following beneficial effects:

[0026] Overcoming the limitations of existing processes - The present invention abandons the traditional technical route of "nanoscale uniform coverage" and allows the antibacterial material to partially adhere to the fiber surface in a discontinuous form. This innovation significantly reduces the process complexity. For example, there is no need to strictly and precisely control the deposition uniformity or precisely match the target material ratio, the fault tolerance rate of the equipment is greatly improved, and the production cost can also be reduced.

[0027] Highly efficient and broad-spectrum antibacterial performance - Silver, titanium, copper and their compounds exert antibacterial effects through multiple mechanisms. For example, silver ions can kill bacteria by destroying the microbial cell membrane, inhibiting enzyme activity and interfering with DNA replication; titanium dioxide can generate reactive oxygen species under light irradiation and decompose the organic structure of microorganisms. Experiments show that even when the coating coverage area is low, it can still have a significant inhibitory effect on common pathogenic microorganisms such as Escherichia coli, Staphylococcus aureus, and Candida albicans.

[0028] Excellent antibacterial durability - The film layer formed by physical vapor deposition is tightly combined with the fiber surface through physical adsorption, chemical bonding or mechanical interlocking, etc., and the washing resistance performance is much better than that of traditional chemical coatings. After multiple standard washings, the decline in antibacterial efficiency is controllable, meeting the long-term use requirements.

[0029] Environmental protection and safety performance - The entire process does not require the use of toxic chemical reagents and there is no wastewater discharge, meeting the green manufacturing standards. In addition, the coating materials (such as silver, titanium, copper) have good biocompatibility and there is no risk of irritation or sensitization when in long-term contact with human skin.

[0030] Wide applicability: The present invention is applicable not only to synthetic fibers (such as polypropylene, polyester), but also to natural fibers such as silk and their blended fabrics (realized by low-temperature deposition technology). By adjusting the deposition parameters, it can be flexibly adapted to the physical and chemical properties of different fibers (such as temperature resistance, surface roughness) to ensure the compatibility between the coating and the substrate. Description of the Drawings

[0031] The drawings are only for the purpose of showing specific embodiments and are not considered to be a limitation of the present invention.

[0032] Figure 1 It is a scanning electron microscope (SEM) photograph of titanium dioxide deposited by DC magnetron sputtering on a polyester fabric obtained in Example 1 of the present invention.

[0033] Figure 2 It is an SEM photograph of silver deposited by RF magnetron sputtering on a mulberry silk fabric obtained in Example 3 of the present invention. Detailed Description of the Invention

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments.

[0035] Example 1: Deposition of Titanium Dioxide by DC Magnetron Sputtering on Polyester

[0036] First step, fabric pretreatment

[0037] Pretreat a polyester shuttle fabric with a grammage of 80 g / m² and a width of 1.6 m. First, immerse the fabric in a deionized water cleaning solution containing 0.3% environmentally friendly surfactant, place it in an ultrasonic cleaning tank with a power density of 20 W / m², and perform ultrasonic treatment at 45 °C for 30 minutes. After cleaning, use a double-roll extrusion device to dehydrate the fabric until the moisture content of the fabric is reduced to less than 10%. Subsequently, it enters a gradient hot air drying system. The temperature of the initial drying zone is set at 50 °C, and the temperature of subsequent zones gradually decreases to 40 °C. The wind speed is controlled at 2 m / s, and the total drying time is 20 minutes. The final moisture content is less than 0.3%. The pretreated fabric is conveyed to the entrance of the deposition chamber through a carbon fiber roller, and the transmission speed is stable at 1 m / min. The accuracy of the dynamic tension control system reaches ±1 N, ensuring that the fabric enters the vacuum environment flat and without wrinkles.

[0038] Second step, vacuum deposition

[0039] Adopt magnetron sputtering technology, and configure 2 groups of high-purity titanium targets (purity 99.95%) in a continuous deposition chamber. The target material size is a diameter of 150 mm and a length of 1800 mm. The target surface is inclined at an angle of 45° to the fabric transmission direction to optimize the deposition uniformity. After the vacuum system pumps the background vacuum degree of the chamber to 5×10 -3 Pa through a cryopump group, introduce high-purity argon and oxygen in an equal volume ratio, and precisely control the working pressure at 0.8 Pa through a mass flow controller. The power of the power supply is set at 2.5 kW, and a dynamic scanning magnetic field device is configured on the target surface. Set the distance between the target and the fabric to 40 mm, and control the substrate temperature at 30 ± 3 °C through a water-cooled copper backplane. This temperature range can not only promote the crystallization of titanium dioxide but also prevent the polyester fiber from melting and deforming due to high temperature.

[0040] Third step, fabric finishing

[0041] The deposited fabric is wound with a constant tension winding device, and the winding tension is controlled at 4.5 ± 0.3 N, and finally an antibacterial polyester fabric with a titanium dioxide coating uniformly attached to the surface is obtained.

[0042] The antibacterial performance was tested by the shaking method according to the national standard GB / T20944.3-2008. Under natural light, after 18 hours of contact, the results showed that the antibacterial rate against Staphylococcus aureus (ATCC6538) was ≥99.0%, and the antibacterial rate against Escherichia coli (8099) was ≥99.3%. Figure 1 The SEM photograph of titanium dioxide magnetron sputtered and deposited on polyester fabric is shown. The picture shows that most of the titanium dioxide deposited on the fabric surface is granular or network-like, and its lateral size ranges from nanoscale to micron scale. Randomly select ten groups of 100 μm×100 μm images of the deposited fabric, and use image software to statistically analyze that the observed coverage area accounts for 8%±2% of the total observable surface area of the fiber, which fully meets the technical standards described in the present invention.

[0043] Example 2: Direct current magnetron sputtering deposition of silver on acrylic

[0044] The first step is fabric pretreatment.

[0045] Pretreat the acrylic non-woven fabric with a gram weight of 60 g / m² and a width of 1.6 m. First, clean the fabric: use a cleaning solution containing 0.5% non-ionic surfactant, and perform ultrasonic treatment on the acrylic fabric for 25 minutes in an ultrasonic cleaning tank with a power density of 18 W / m² at 40°C. The cleaned fabric is processed by a double-roll extrusion dehydration device to reduce the moisture content to less than 12%. Subsequently, it enters a segmented hot air drying system. The initial drying zone temperature is set at 50°C, and the subsequent zones are gradually cooled to 40°C. The wind speed is controlled at 2 m / s, and the total drying time is 18 minutes. The final moisture content is less than 0.4%. The fabric is conveyed to the deposition chamber through a carbon fiber roller, and the transmission speed is stable at 1 m / min. The accuracy of the dynamic tension control system reaches ±1 N, ensuring that the fabric has no jitter or deviation during high-speed transmission.

[0046] The second step is vacuum deposition.

[0047] The deposition process uses high-density direct current magnetron sputtering technology. Four parallel targets are continuously installed in the advancing direction of the fabric. The target is a columnar silver target with a purity of 99.99%, a diameter of 150 mm, and a length of 1800 mm. The installation angle of the target is adjusted to 30° inclined configuration to optimize the sputtered particle flow distribution. The vacuum system pumps the background vacuum degree of the chamber to 2×10 -3 Pa through a turbo molecular pump set, and then high-purity argon gas (99.99%) is introduced. The working pressure is accurately controlled at 0.5 Pa through a piezoelectric gas flow controller. The DC power supply outputs in a constant current mode with a power of 2 kW, and a rotating magnetic field device is equipped on the target surface. The distance between the target and the fabric is set at 40 mm. During the deposition process, the substrate temperature is controlled at 35±3°C through a back-cooled copper plate. This temperature range can not only promote the diffusion and combination of silver particles on the acrylic surface but also avoid fiber thermal shrinkage.

[0048] The third step is fabric finishing.

[0049] After the deposition is completed, the fabric is wound up online. The winding tension is controlled at 4.5 ± 0.3 N by a magnetic powder clutch, and the deposited fabric is stored.

[0050] The antibacterial performance is tested according to the oscillating method of GB / T20944.3-2008. After 18 hours of contact, the results show that the antibacterial rate against Staphylococcus aureus (ATCC6538) is ≥ 99.3%, and the antibacterial rate against Escherichia coli (8099) is ≥ 99.6%. Randomly select ten groups of images of the deposited fabric with a size of 100 μm × 100 μm. The observed silver plating particles and network sizes range from nanoscale to micron scale, and their coverage area accounts for 20% ± 1% of the total observable surface area of the fiber, fully meeting the technical standards described in the present invention.

[0051] Example 3: Radio frequency magnetron sputtering deposition of silver on mulberry silk fabric

[0052] The first step is fabric pretreatment

[0053] Pretreat multiple mulberry silk fabric samples with a size of 500 × 500 / 10 cm and a length and width of 10 cm × 10 cm. Place the silk fabric samples in a glass sealed container containing acetone solution. Put the glass sealed container into an ultrasonic washer and oscillate and wash for 60 min to remove impurities such as dust and organic solvents on the fabric surface. After the above treatment, take out the fabric, wash it repeatedly with deionized water 10 times, and then put it into an oven at 40 °C for 24 hours to dry.

[0054] The second step is vacuum deposition

[0055] Using radio frequency magnetron sputtering technology, metallic silver with a purity of 99.99% and a diameter of 80 mm is sputter-deposited in an upward direction. The basic sputter deposition conditions are as follows: the base vacuum is 5×10 -4 Pa, the distance between the target and the silk fabric is 10 cm, the purity of argon introduced after reaching the base vacuum is 99.99%, the pressure during sputter deposition is 2 Pa, the sputter power is 150 W, the sputter time is 50 s, and the temperature of the silk fabric is controlled at 30 °C through a water cooling system.

[0056] The third step is fabric finishing

[0057] Use a storage device to take out the deposited fabric from the sputtering chamber, and then perform encapsulation.

[0058] The antibacterial performance is tested according to the oscillating method of GB / T20944.3-2008, and the results show that the antibacterial rate against Staphylococcus aureus (ATCC6538) is ≥ 95.0%, and the antibacterial rate against Escherichia coli (8099) is ≥ 96.1%.Figure 2 The SEM photos of silver deposited on silk fabric by radio frequency magnetron sputtering are shown. The pictures show that most of the silver deposited on the fabric surface is in the form of particles or networks, and their lateral dimensions vary from nanometer scale to micrometer scale. After statistically analyzing the deposited area and the silk area of ten groups of images of the deposited silk fabric, it is found that the observed coverage area of the deposit accounts for 4% ± 1% of the total observable surface area of the fibers, which fully meets the technical standards described in the present invention.

[0059] The above embodiments fully disclose the technical solutions of the present invention. Those skilled in the art can make adaptive adjustments to the parameters according to actual production requirements, and such adjustments all fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing an antibacterial fabric based on physical vapor deposition, characterized in that, Depositing particles, networks or film layers on the surface of a fabric by physical vapor deposition. The particles, networks or film layers are at least one metal among silver, titanium, copper with a thickness of 0.5 nm to 1 μm, or at least one of their oxides or nitrides. Under a microscope, the proportion of the observable coverage area of the deposited particles, networks or film layers on the surface of the fibers that make up the fabric to the total observable surface area of the fibers satisfies the following conditions: When the thickness is 0.5 nm to less than 5 nm, the coverage area ≥ 1%; When the thickness is 5 nm to 1 μm, the coverage area ≥ 0.1%; If there are both thicknesses of 0.5 nm to 5 nm and 5 nm to 1 μm, the total coverage area ≥ 1%.

2. The preparation method according to claim 1, wherein It includes the following steps: Fabric pretreatment: Place the fabric in a cleaning solution to remove surface contaminants, and after drying, fix it on the loading mechanism of the physical vapor deposition equipment; Vacuum deposition: Deposit the particles, networks or film layers of the metal or metal compound by physical vapor deposition technology; Fabric finishing: Store the deposited fabric.

3. The preparation method according to claim 1, characterized in that, The morphology of the particles, networks or film layers includes island-like films, dispersed particles, nanorods or nanoscale clusters.

4. The preparation method according to claim 1, characterized in that, The control methods for the thickness, distribution density and morphology of the particles, networks or film layers are achieved by adjusting parameters such as power, gas flow rate, distance between the target and the deposited fabric, fabric temperature, and deposition time during the deposition process.

5. The preparation method according to claim 1, characterized in that, The fabric includes synthetic fibers, natural fibers or their blended fabrics.

6. The preparation method according to claim 2, characterized in that, The physical vapor deposition technology includes vacuum evaporation plating, magnetron sputtering plating or ion plating.

7. The preparation method according to claim 2, characterized in that, The methods for depositing oxides and nitrides on the fabric surface include depositing with a corresponding oxide or nitride target, and in-situ generating metal oxides or nitrides by introducing reaction gases during the deposition process.

8. The preparation method according to claim 2, characterized in that, In the vacuum deposition step, reaction gases are introduced, and the reaction gases include oxygen and nitrogen.

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