Scratch-resistant medical antibacterial breathable film and method of making same

Abstract

The present application relates to a kind of scratch-resistant medical antibacterial breathable film and its preparation method, the film includes breathable wear-resistant layer, PET breathable layer and antibacterial breathable layer in turn;Breathable wear-resistant layer includes PET resin, scratch-resistant master batch, lubricating dispersant and auxiliary agent;PET breathable layer includes matrix resin, nanoscale rigid filler master batch, compatibilizer and auxiliary agent;Antibacterial breathable layer includes PET resin, nano silver, chitosan quaternary ammonium salt, nanoscale rigid filler master batch and auxiliary agent.The film of the present application is prepared by co-extrusion and bidirectional stretching, the thickness is 70-90 μm, the pore size is 80-400 nm, can reduce the amount of chitosan derivative, avoid nano silver oxidation blackening and shedding defect, solve the problem that existing wound film is not breathable and easily causes wound deterioration, simply and low cost continuously prepare scratch-resistant antibacterial breathable film.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of polyester-based composite film, and particularly relates to a scratch-resistant medical antibacterial breathable film and a preparation method thereof. BACKGROUND

[0002] With the development of science and technology and the progress of society, people pay more and more attention to their living environment and health status, and infectious diseases caused by pathogenic microorganisms have been one of the main threats to human health. Antibacterial film material is a new type of material that has both bacteriostatic and bactericidal properties, that is, by adding an antibacterial agent to plastic, the plastic film itself has bacteriostatic properties, and can kill or inhibit the reproduction of bacteria adhering to the film within a certain period of time, and can be widely used in packaging materials, shopping bags, storage bags, garbage bags, and film materials, etc., greatly reducing the probability of people being infected with bacteria and improving the quality of the living environment. Antibacterial film also plays an essential role in the medical field, which can block further invasion of bacteria to the wound and cause infection, and some antibacterial films can also promote wound healing and reduce wound proliferation.

[0003] Antibacterial film has undergone a long development process. The initial antibacterial wound protection material is composed of gauze and antibacterial drugs. With the development of science and technology and the rapid changes in film technology, many antibacterial films have been developed accordingly. Antibacterial materials have developed from coating ordinary antibacterial agents to using new antibacterial agents such as nano-silver, chitosan, and metal ions. The substrate has developed from PP to PVA, PET, PC, etc. The function has developed from single antibacterial to multifunctional synergy. Patent CN106079779B discloses a breathable antibacterial film and a waterproof breathable antibacterial film comprising a breathable antibacterial film layer, the breathable antibacterial film comprising a surface layer, a coating layer and a substrate layer; the coating layer is coated on the substrate layer, and the surface layer is combined with the substrate layer; the substrate layer comprises, from top to bottom, a first fabric, an ordinary TPU adhesive layer and a second fabric, which are sequentially attached; the antibacterial polyester TPU surface layer material adds nano-silver antibacterial agent, and the addition amount is 2.5-5.5% of the mass of the surface layer polyester TPU. Patent application CN112123885A discloses a chitosan-nano-silver composite antibacterial fabric and a preparation method thereof. The antibacterial fabric comprises a waterproof layer and a hydrophilic layer, and a base layer, an adhesive layer and an antibacterial layer are sequentially stacked between the waterproof layer and the hydrophilic layer, and the antibacterial layer is loaded with an antibacterial compound; the antibacterial layer is chitosan-nano-silver, the mass ratio of nano-silver to chitosan is 1:100, the particle size of nano-silver is 50-100 nm, and the grammage is 6 oz.

[0004] However, the existing antibacterial breathable film generally has the following problems:

[0005] 1. The antibacterial property of chitosan in chitosan antibacterial film is weak, and it is difficult to achieve ideal antibacterial effect. At the same time, the mechanical property of chitosan film is poor, and it cannot be applied to most scenes that need to be repeatedly bent in the environment.

[0006] 2. Although chitosan has good film-forming property, its production continuity is poor. Generally, it is coated into a film by dissolving in a solvent, which greatly limits its mass production.

[0007] 3. Nano-silver is the most commonly used antibacterial material, but it is easy to oxidize to produce silver oxide, resulting in a series of problems such as blackening and reduced antibacterial effect. Nano-silver is generally added as a filler into the base material. The small size leads to easy aggregation and uneven antibacterial performance. Moreover, nano-silver particles are easy to fall off from the surface of the base material, thereby reducing the antibacterial ability of the material. The porous material with a larger contact surface further increases the amount of nano-silver falling off.

[0008] In order to solve the above problems, researchers in the fields of materials and medicine have been continuously researching. Patent CN108969791B discloses a composite wound dressing loaded with nano-silver and a preparation method thereof. The dressing is prepared by loading nano-silver particles on the basis of sodium cellulose sulfonate, chitosan or chitosan derivatives. In the preparation, silver nitrate solution, chitosan acetic acid aqueous solution and cellulose sulfonate aqueous solution are mixed and stirred. Chitosan and cellulose sulfonate form a polyelectrolyte complex. In the light-shielded and heated conditions, sodium citrate is added to reduce the silver nitrate in the polyelectrolyte complex in situ to prepare nano-silver. The complex is freeze-dried to form the composite wound dressing loaded with nano-silver. The dressing provided by the patent mainly uses a discontinuous production method, which has low production efficiency, high cost and is difficult to mass-produce and popularize. Moreover, the product has low strength and limited application scenarios. Patent CN109463381B discloses a quaternary ammonium salt-nano-silver type magnetic nano-antibacterial composite particle, a preparation method and application thereof. The process is as follows: Fe3O4 nanoparticles are prepared by coprecipitation; Fe3O4-PAA is synthesized by modifying magnetic Fe3O4 nanoparticles with polymethyl acrylic acid; Fe3O4-PAA-(CS-CA)n is obtained by assembling 2-hydroxypropyltrimethylammonium chloride chitosan as a cationic assembly liquid and sodium citrate as an anionic assembly liquid on the Fe3O4 nanoparticles; and Fe3O4-PAA-(CS-CA)n is boiled with AgNO3 to generate nano-silver particles in situ on the assembly layer on the surface of the nanoparticles. In addition to the same defects as the aforementioned patent in terms of continuous production and strength, the product of the patent is mainly in the laboratory stage, and the actual application cost and quality stability are difficult to control.

[0009]

[0010] ​Therefore, how to reduce the amount of chitosan and its derivatives and improve their antibacterial properties, solve the problems of oxidation and blackening of nano-silver and easy detachment, and improve the breathability of composite films to prevent wound deterioration, etc., are practical application problems. In particular, the simple, continuous and low-cost preparation of antibacterial and breathable films has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0011] To address the shortcomings of the existing technology, the present invention aims to provide a scratch-resistant medical antibacterial and breathable film and its preparation method. The film utilizes a composite of nano-silver and chitosan derivatives, reducing the amount of chitosan derivatives used while stabilizing and slow-release the nano-silver, thereby comprehensively improving the antibacterial and antimicrobial properties and durability of the product. The preparation process employs continuous co-extrusion and biaxial stretching to ensure overall mechanical properties while increasing the film pore size to improve breathability, and achieving low-cost mass production.

[0012] Specifically, the present invention provides a scratch-resistant medical antibacterial breathable film, which comprises, in sequence, a breathable and wear-resistant layer, a breathable layer, and an antibacterial breathable layer;

[0013] A breathable and abrasion-resistant layer, 10-20 μm thick, comprising, by weight percentage:

[0014]

[0015] The PET breathable layer, 10-20μm thick, comprises, by weight percentage:

[0016]

[0017] An antibacterial and breathable layer, 30-50 μm thick, comprising, by weight percentage:

[0018] 70-80% PET resin

[0019] Nano silver 4-8%

[0020] Chitosan quaternary ammonium salt 5-10%

[0021] 5-10% nanoscale rigid filler masterbatch

[0022] Additives 2-6%;

[0023] The scratch-resistant medical antibacterial breathable film is prepared by co-extrusion followed by biaxial stretching, with a film thickness of 70-90μm and a film pore size of 80-400nm.

[0024] In addition to using virgin PET resin, the PET resin used in this invention can also incorporate a certain amount of recycled production materials; the specific materials used can be selected according to the application scenario. Secondly, scratch-resistant masterbatch is added to the breathable and abrasion-resistant layer to provide scratch resistance, while nano-silver and chitosan quaternary ammonium salt are added to the antibacterial and breathable layer to provide long-lasting and stable antibacterial and bacteriostatic properties. Furthermore, the arrangement of organic / inorganic components in each layer provides good porosity, resulting in overall high breathability of the film. The pore size is controlled at 80-400 nm, and the porosity at 70-90%, which is smaller than the water droplet permeability size (approximately 500 nm) and larger than the gas permeability size (e.g., O2 approximately 0.173 nm, CO2 approximately 0.165 nm, and water vapor approximately 0.1325 nm), thus ensuring that water droplets cannot pass through while other gases can pass smoothly. In addition, through co-extrusion and biaxial stretching processes, the thickness, film pore size, and porosity are controllable, enabling large-scale continuous production.

[0025] The abrasion-resistant masterbatch is selected from at least one of polysiloxane abrasion-resistant agents and surface-treated carbon nanotubes. A lubricating dispersant is used in conjunction to improve the dispersion performance of the abrasion-resistant masterbatch; the lubricating dispersant is selected from at least one of erucamide, EBS, PETS, and calcium stearate. The compatibilizer is selected from at least one of POE-g-MAH and POE-g-GMA to improve the compatibility of the interlayer resins and overall enhance the mechanical properties and peel resistance of the layered material. The nano-scale rigid filler masterbatch is preferably nano-calcium carbonate masterbatch, which can be a commercially available product or self-made.

[0026] The preferred quaternary ammonium salt for chitosan is hydroxypropyl dimethyl ammonium chloride chitosan. Although nano-silver and chitosan quaternary ammonium salt can be added to PET resin separately, it is preferred to first combine the two. The method of combining can be to use commercially available nano-silver and chitosan quaternary ammonium salt to blend and combine. More preferably, a composite material with uniformly dispersed nano-silver and effectively protected can be prepared by using a combination of physicochemical methods.

[0027] Furthermore, the additives for the wear-resistant and breathable layer, the additives for the PET breathable layer, and / or the additives for the antibacterial and breathable layer include at least one of the following: antioxidants, PET nucleating agents, opening agents, and color masterbatches;

[0028] Specifically, the antioxidant is selected from at least one of Rianlon 1098, Rianlon 1076, Rianlon 168, and Rianlon 626; the weight percentage is 0.2-2%;

[0029] The PET nucleating agent is selected from at least one inorganic nucleating agent and an organic nucleating agent; the weight percentage is 0.2-2%;

[0030] Optionally, the opening agent is selected from at least one of micron-sized BaSO4 and SiO2; the weight percentage is 0-2%;

[0031] Optional, color masterbatch, 0-3% by weight.

[0032] The above-mentioned additives can be commercially available products, and can be pre-sieved according to particle size requirements. Specifically, the additives for the wear-resistant and breathable layer preferably include antioxidants and PET nucleating agents, and opening agents and color masterbatches are optional. The additives for the PET breathable layer preferably include antioxidants and PET nucleating agents, and lubricating and dispersing agents are also optional. The additives for the antibacterial breathable layer preferably include antioxidants and PET nucleating agents, and lubricating and dispersing agents are also optional.

[0033] Furthermore, the matrix resin of the PET breathable layer, by weight percentage, comprises:

[0034] PET resin 85-95%

[0035] 5-15% of the compound resin

[0036] The compounding resin is selected from at least one of LDPE, copolymer PP, and TPE.

[0037] Unlike existing membrane materials that use pure PET resin, this invention adds a small amount of resin with poor compatibility with PET to the PET resin body in addition to adding nano-level rigid filler masterbatch. This helps to obtain breathable pores during the biaxial stretching stage, resulting in a highly breathable PET breathable layer.

[0038] Furthermore, in the antibacterial and breathable layer, the chitosan quaternary ammonium salt is hydroxypropyl dimethyl ammonium chloride chitosan, and the nano-silver and hydroxypropyl dimethyl ammonium chloride chitosan form nano-silver / hydroxypropyl dimethyl ammonium chloride chitosan composite microspheres. Choosing this composite microsphere configuration not only facilitates good synergistic stability between the nano-silver and chitosan derivatives, creating a synergistic effect of mutual protection and enhancement, but also improves dispersion in the resin during processing, enhancing uniformity.

[0039] Preferably, the nano-silver / hydroxypropyl dimethylammonium chloride chitosan composite microspheres are prepared by the following steps:

[0040] S1. Preparation of silver / chitosan composite microspheres

[0041] S1.1 Prepare aqueous solutions of silver nitrate and sodium borohydride respectively;

[0042] S1.2 Add chitosan to an aqueous solution of silver nitrate and stir to obtain a chitosan suspension;

[0043] Under nitrogen protection, the chitosan suspension was heated to 35-42℃, sodium borohydride aqueous solution was added dropwise, the reaction was stirred for 20-40 min, and then cooled to obtain the nano silver / chitosan complex.

[0044] S1.4 Add glutaraldehyde, with the preferred mass ratio of glutaraldehyde to chitosan being (0.1-2):100. Stir at room temperature for 2-5 hours to obtain a nano-silver / chitosan composite microsphere emulsion. Centrifuge, wash, and vacuum dry to obtain nano-silver / chitosan composite microspheres.

[0045] S2. Preparation of nano-silver / hydroxypropyl dimethylammonium chloride chitosan composite microspheres

[0046] S2.1 Disperse the nano-silver / chitosan composite microspheres in isopropanol;

[0047] S2.2 Heat to 55-65℃, add cyclopropyl dimethyl diethyl ammonium chloride isopropanol dropwise, react for 10-15 hours, and let stand to separate into layers;

[0048] S2.3 was precipitated by adding anhydrous ethanol, filtered, and dried under vacuum to obtain nano-silver / hydroxypropyl dimethyl ammonium chloride chitosan microspheres.

[0049] This invention first prepares a nano-silver / chitosan composite through reduction, and then reacts to prepare a chitosan quaternary ammonium salt. This results in more uniform particle size and deposition of the nano-silver. Furthermore, the presence of hydroxyl groups at the ortho-positions of the amino groups in the chitosan molecules allows for the formation of cage-like molecules with a network-like structure via hydrogen bonds and salts. This provides a more stable coordination structure and protective enclosure for the previously deposited nano-silver, effectively controlling the oxidation and release rate of the nano-silver. By preparing composite microspheres, the nano-silver is well protected and dispersed. These composite microspheres can be either first blended with a small amount of PET resin to create a masterbatch before being added to a larger amount of PET resin matrix, or they can be directly added to PET resin, simplifying the process.

[0050] Furthermore, the nanoscale rigid filler masterbatch includes nano-calcium carbonate masterbatch, which is prepared through the following steps:

[0051] (1) Preparation of surface-treated nano-calcium carbonate

[0052] (1.1) Disperse CaO in deionized water by ultrasonication to form Ca(OH)2 slurry, let it stand and then sieve to remove large particles;

[0053] (1.2) Add surface treatment agent, stir, and introduce a mixture of CO2 and N2 gas. React at 15-20℃, filter, and wash.

[0054] (1.3) Dry in an oven at 70-90℃ for 8-15 hours to obtain surface-treated nano-calcium carbonate particles;

[0055] (2) Preparation of nano-calcium carbonate masterbatch

[0056] (2.1) Surface-treated nano-calcium carbonate is mixed with ethylene glycol and ultrasonically dispersed; then it is added to the reaction vessel along with terephthalic acid and antimony acetate and stirred and mixed.

[0057] (2.2) Under nitrogen pressure, the temperature is increased to 200-250℃ at a rate of 3-5℃ / min to carry out the esterification reaction;

[0058] (2.3) Evacuate to 200-300 Pa and polymerize for 1-3 hours;

[0059] (2.4) Extrusion, water cooling, pelletizing, and drying yield nano-calcium carbonate masterbatch.

[0060] The surface treatment agent is selected from at least one of phosphate ester (salt) modifiers (e.g., polyethylene glycol phosphate PGP), silane coupling agents, borate ester coupling agents, stearic acid (salt), and quaternary ammonium salt surface treatment agents. The ash content of the prepared nano-calcium carbonate masterbatch is preferably 30-40 wt%.

[0061] Furthermore, the scratch-resistant masterbatch contains at least one of the following: a polysiloxane abrasion resistant agent with a molecular weight of 1.2-1.5 million, and carbon nanotubes surface-treated with sodium dodecylbenzene sulfonate (SDBS). The surface treatment of the carbon nanotubes includes: preparing a mixed aqueous solution of carbon nanotubes and sodium dodecylbenzene sulfonate at a mass ratio of (2-3):1, wherein the dispersion concentration of the carbon nanotubes can be selected as 20-30 g / L; ultrasonic water bath treatment for 1-2 hours; filtration; and vacuum drying.

[0062] Furthermore, on the other layer of the antibacterial breathable layer relative to the PET breathable layer, there is also an adhesive layer, 5-10 μm thick, which, by weight percentage, contains the following raw material components:

[0063] Adhesive 90-95%

[0064] Chitosan 0-5%

[0065] Nano silver 0-5%;

[0066] The adhesive is selected from at least one of medical-grade natural maleic gum, medical-grade acrylic adhesive, medical-grade water-based latex, and medical-grade solvent-based adhesive. For example, commercially available medical-grade water-based latex SH-820 and medical-grade maleic gum H0207 are used. It is required to have good compatibility with other components, good flowability, no skin sensitization, and to consider the subsequent drug loading requirements of adhering closely to the inner layer of the wound.

[0067] Regarding the aforementioned scratch-resistant medical antibacterial breathable film, the present invention also provides a corresponding method for preparing the scratch-resistant medical antibacterial breathable film, comprising the following steps:

[0068] Step 1: Prepare the raw materials for the wear-resistant breathable layer, PET breathable layer and antibacterial breathable layer. Put the raw materials of each layer into the mixer to mix, and then feed them into the corresponding extruders after metering.

[0069] Step 2: After the raw materials of each layer are melted and filtered, they are extruded into a three-layer co-extrusion die and electrostatically adsorbed onto the cold roller to form a cast sheet;

[0070] Step 3: First stretch vertically, then stretch horizontally;

[0071] Step 4: Perform single-sided or double-sided corona treatment to obtain a corona layer with a thickness of 3-10μm, remove static electricity, and rewind;

[0072] Step 5: Slitting; or apply an adhesive layer to the other side of the antibacterial breathable layer opposite the PET breathable layer, attach a release film, and slit.

[0073] Furthermore, the temperature of the three-layer co-extrusion die is 200-220℃, the speed of the cold roller is 18-35m / min, the temperature is 20-35℃, and the thickness of the cast sheet is 400-950μm; the longitudinal stretching ratio is 2.4-4.0, and the transverse stretching ratio is 2.6-4.0.

[0074] Preferably, in the longitudinal stretching stage, the preheating temperature is 70-80℃, the cooling temperature is 20-30℃, the setting temperature is 30-50℃, and the stretching ratio is 2.4-4; in the transverse stretching stage, the preheating temperature is 95-105℃, the stretching temperature is 100-115℃, the setting temperature is 110-120℃, the cooling temperature is 30-60℃, and the stretching ratio is 2.6-4.

[0075] The advantages of this invention are as follows:

[0076] (1) The scratch-resistant medical antibacterial breathable film of the present invention has stable and long-lasting antibacterial and bacteriostatic properties. It adopts a composite of nano-silver and chitosan derivative with excellent antibacterial properties, especially in the form of nano-silver / hydroxypropyl dimethyl ammonium chloride chitosan composite microspheres. This not only forms a uniform dispersion and stable coordination effect on nano-silver, preventing nano-silver from being ineffectively oxidized, but also provides sustained-release regulation for subsequent nano-silver, thus prolonging the antibacterial and bacteriostatic effect of the film.

[0077] (2) By adding scratch-resistant masterbatch to the outward breathable and wear-resistant layer material, the present invention effectively improves the overall abrasion resistance of the film, meeting the needs of actual transportation, storage and use. Furthermore, the present invention uses the addition of organic / inorganic components, which causes the PET resin as the main component to exhibit a non-uniform steric hindrance effect during biaxial stretching, resulting in tearing cracks and achieving a breathable effect. Moreover, by controlling the amount of resin, inorganic material and size, the overall breathability of the film can be effectively controlled.

[0078] (3) The method for preparing scratch-resistant medical antibacterial and breathable film provided by the present invention breaks the discontinuous preparation process of traditional chitosan antibacterial products and achieves low-cost and continuous production based on the PET composite film preparation process. Attached Figure Description

[0079] The above and other objects, features and advantages of exemplary embodiments of this disclosure will become readily understood by reading the following detailed description with reference to the accompanying drawings.

[0080] Figure 1 This is a schematic diagram of the structure of the scratch-resistant medical antibacterial breathable film of the present invention.

[0081] Explanation of reference numerals in the attached diagram: 1. Breathable and wear-resistant layer, 2. PET breathable layer, 3. Antibacterial and breathable layer, 4. Adhesive layer, 5. Corona layer. Detailed Implementation

[0082] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will now be described in further detail with reference to the accompanying drawings.

[0083] In one aspect, a scratch-resistant medical antibacterial and breathable film comprises, in sequence: a breathable and abrasion-resistant layer 1, a PET breathable layer 2, an antibacterial and breathable layer 3, and an optional adhesive layer 4; specifically,

[0084] (1) Breathable and wear-resistant layer 1, 10-20 μm thick, comprising, by weight percentage:

[0085]

[0086] The PET resin used is high-gloss film-grade PET resin. In addition to virgin PET resin, a certain amount of recycled production material can be incorporated, controlling the ratio of virgin to recycled material at (5-7):(1-3). Under similar conditions, the product performance difference is minimal. The scratch-resistant masterbatch is selected from at least one of the following: polysiloxane abrasion resistant agents with a molecular weight of 1.2-1.5 million, and carbon nanotubes surface-treated with sodium dodecylbenzene sulfonate. The lubricating dispersant is selected from at least one of erucamide, EBS, PETS, and calcium stearate.

[0087] The adjuvants include antioxidants selected from at least one of Rianlon 1098, Rianlon 1076, Rianlon 168, and Rianlon 626; the weight percentage is 0.2-2%;

[0088] The PET nucleating agent is selected from at least one of inorganic and organic nucleating agents, with a weight percentage of 0.2-2%. Inorganic nucleating agents include clays such as montmorillonite, kaolin, and hydrotalcite; metal oxides such as SiO2, MgO, ZnO, and TiO2; inorganic salts such as Na2CO3, NaHCO3, and BaSO4; and non-alkali metal hydroxides such as Al(OH)3 and Mg(OH)2. Inorganic nucleating agents are inexpensive and easy to use, but they are heterogeneous nucleating agents with poor dispersibility and generally poor nucleation effects. Organic nucleating agents mainly include benzoates, ethylene glycol esters, ethylenediamine, and ionomers, which have high compatibility with PET and better nucleation effects, but are relatively expensive. Composite nucleating agents can also be formed by combining the above-mentioned nucleating agents. Different nucleating agents exhibit different advantages, easily achieving synergistic effects and balancing performance and cost advantages. The opening agent is selected from at least one of micron-sized BaSO4 and SiO2, with a weight percentage of 0-2%; the color masterbatch has a weight percentage of 0-3%; in addition, nano-sized rigid filler masterbatch can also be added to this layer according to the air permeability requirements.

[0089] (2) PET breathable layer 2, 10-20μm thick, comprising, by weight percentage:

[0090]

[0091] The PET resin used is a glossy film-grade PET resin; the matrix resin includes 85-95% PET resin and 5-15% compounding resin, wherein the compounding resin is selected from at least one of LDPE, copolymer PP, and TPE; the nano-level rigid filler masterbatch includes nano-calcium carbonate masterbatch; the compatibilizer is selected from at least one of POE-g-MAH and POE-g-GMA; the selection of additives can be the same as or different from that of the breathable and wear-resistant layer 1;

[0092] (3) Antibacterial and breathable layer 3, 30-50 μm thick, comprising, by weight percentage:

[0093]

[0094] Among them, the PET resin used is high-gloss film-grade PET resin; the chitosan quaternary ammonium salt is hydroxypropyl dimethyl ammonium chloride chitosan, and nano-silver and hydroxypropyl dimethyl ammonium chloride chitosan form nano-silver / hydroxypropyl dimethyl ammonium chloride chitosan composite microspheres; the selection of additives can be the same as or different from that of the breathable and wear-resistant layer 1.

[0095] (4) Adhesive layer 4, on the other side of antibacterial breathable layer 3 relative to PET breathable layer 2, with a thickness of 5-10 μm, and comprising the following raw material components by weight percentage:

[0096] Adhesive 90-95%

[0097] Chitosan 0-5%

[0098] Nano silver 0-5%;

[0099] The adhesive is selected from at least one of medical-grade natural maleic gum, medical-grade acrylic acid, medical-grade water-based latex, and medical-grade solvent-based adhesive. Commercially available medical-grade water-based latex SH-820, medical-grade maleic gum H0207, etc., can be used.

[0100] Secondly, the present invention further provides a method for preparing a scratch-resistant medical antibacterial and breathable film, comprising the following steps:

[0101] Step 1: Prepare the raw materials for the wear-resistant breathable layer, PET breathable layer 2, and antibacterial breathable layer 3. Put the raw materials of each layer into a mixer and mix them separately. After metering, feed them into the corresponding extruders. Specifically, use a high-speed mixer at a speed of 500-600 r / min and mix for 15-20 min. The extruder temperature should be 200-260℃.

[0102] The nano-silver / hydroxypropyl dimethylammonium chloride chitosan composite microspheres were prepared through the following steps:

[0103] S1. Preparation of silver / chitosan composite microspheres

[0104] S1.1 Prepare aqueous solutions of silver nitrate and sodium borohydride respectively;

[0105] S1.2 Add chitosan to an aqueous solution of silver nitrate and stir to obtain a chitosan suspension;

[0106] Under nitrogen protection, the chitosan suspension was heated to 35-42℃, sodium borohydride aqueous solution was added dropwise, the reaction was stirred for 20-40 min, and then cooled to obtain the nano silver / chitosan complex.

[0107] S1.4 Add glutaraldehyde, with a mass ratio of glutaraldehyde to chitosan of (0.1-2):100, stir at room temperature for 2-5 hours to obtain a nano-silver / chitosan composite microsphere emulsion. Centrifuge, wash, and vacuum dry to obtain nano-silver / chitosan composite microspheres. Use a small amount of glutaraldehyde to lightly crosslink the chitosan to facilitate the shaping of the microspheres.

[0108] S2. Preparation of nano-silver / hydroxypropyl dimethylammonium chloride chitosan composite microspheres

[0109] S2.1 Disperse the nano-silver / chitosan composite microspheres in isopropanol;

[0110] S2.2 Heat to 55-65℃, add cyclopropyl dimethyl diethyl ammonium chloride isopropanol dropwise, react for 10-15 hours, and let stand to separate into layers;

[0111] S2.3 was precipitated by adding anhydrous ethanol, filtered, and dried under vacuum to obtain nano-silver / hydroxypropyl dimethyl ammonium chloride chitosan microspheres.

[0112] Nanoscale rigid filler masterbatch, including nano-calcium carbonate masterbatch, is prepared through the following steps:

[0113] (1) Preparation of surface-treated nano-calcium carbonate

[0114] (1.1) Disperse CaO in deionized water by ultrasonication to form Ca(OH)2 slurry, let it stand and then sieve to remove large particles;

[0115] (1.2) Add surface treatment agent, stir, and introduce a mixture of CO2 and N2 gas. React at 15-20℃, filter, and wash.

[0116] (1.3) Dry in an oven at 70-90℃ for 8-15 hours to obtain surface-treated nano-calcium carbonate particles;

[0117] (2) Preparation of nano-calcium carbonate masterbatch

[0118] (2.1) Surface-treated nano-calcium carbonate is mixed with ethylene glycol and ultrasonically dispersed; then it is added to a reaction vessel along with terephthalic acid and antimony acetate and stirred and mixed; wherein the mass ratio of terephthalic acid to ethylene glycol is (2-3):1, and the amount of antimony acetate is about 0.1-0.5% of the mass of terephthalic acid;

[0119] (2.2) Under nitrogen pressure, the temperature is increased to 200-250℃ at a rate of 3-5℃ / min to carry out the esterification reaction;

[0120] (2.3) Evacuate to 200-300 Pa and polymerize for 1-3 hours;

[0121] (2.4) Extrusion, water cooling, pelletizing, and drying yield nano-calcium carbonate masterbatch.

[0122] The surface treatment agent in step (1.2) is selected from at least one of phosphate ester (salt) modifiers (e.g., polyethylene glycol phosphate PGP), silane coupling agents, borate ester coupling agents, stearic acid (salt), and quaternary ammonium salt surface treatment agents. The ash content of the prepared nano-calcium carbonate masterbatch is preferably 30-40 wt%.

[0123] Step 2: After the raw materials of each layer are melted and filtered, they are extruded into a three-layer co-extrusion die and electrostatically adsorbed onto the cold roller to form a cast sheet. Specifically, a 10-20μm pore size filter is used, and the filter temperature is set at 240-260℃; the temperature of the three-layer co-extrusion die is 200-220℃, the cold roller speed is 18-35m / min, the temperature is 20-35℃, and the cast sheet thickness is 400-950μm. The thickness ratio of each layer of the film is adjusted by controlling the melt ratio of each extruder.

[0124] Step 3: First stretch longitudinally, then stretch laterally; the preferred heating method is infrared heating, specifically...

[0125] (1) Longitudinal stretching stage, preheating temperature 70-80℃, cooling temperature 20-30℃, setting temperature 30-50℃, stretching ratio 2.4-4.0, preferably 2.5-3.8;

[0126] (2) In the transverse stretching stage, the preheating temperature is 95-105℃, the stretching temperature is 100-115℃, the setting temperature is 110-120℃, the cooling temperature is 30-60℃, and the stretching ratio is 2.6-4.0, preferably 3-4.

[0127] Step 4: Double-sided corona treatment, obtaining corona layers 5 with a thickness of 3-10μm on both sides, removing static electricity, and winding up;

[0128] Step 5: Slitting; or, on the other side of the antibacterial breathable layer 3 opposite to the PET breathable layer 2, an adhesive layer 4 is formed, a release film is attached, and then slitting is performed; specifically, the rolled-up film can be coated on the coating line, with a preheating temperature of 40-50℃ and a coating amount of 15-30g / m². 2 Cool to room temperature.

[0129] By adjusting the materials and proportions of each component layer, and through a simple and continuous preparation method, this invention can provide a scratch-resistant medical antibacterial and breathable film with a thickness of 70-90 μm and a pore size of 80-400 nm.

[0130] Example 1

[0131] The scratch-resistant, antibacterial, and breathable medical film of this embodiment has a thickness of approximately 75 μm and a pore size of 150-250 nm, and comprises, in sequence:

[0132] (1) A breathable and abrasion-resistant layer, 15 μm thick, comprising, by weight percentage:

[0133]

[0134]

[0135] (2) A PET breathable layer, 15 μm thick, comprising, by weight percentage:

[0136]

[0137] (3) An antibacterial and breathable layer, 40 μm thick, comprising, by weight percentage:

[0138] 50% virgin PET resin

[0139] 24% of PET resin production uses recycled materials.

[0140] 15% Nano Silver / Hydroxypropyl dimethyl ammonium chloride chitosan premix

[0141]

[0142]

[0143] (4) Adhesive layer, on the other side of the antibacterial breathable layer relative to the PET breathable layer, with a thickness of 5 μm, comprising the following raw material components by weight percentage:

[0144] Medical Waterborne Latex SH-820 95%

[0145] Chitosan 2.5%

[0146] Nano silver 2.5%;

[0147] Secondly, the present invention further provides a method for preparing a scratch-resistant medical antibacterial and breathable film, comprising the following steps:

[0148] Step 1: Prepare the raw materials for the wear-resistant breathable layer, PET breathable layer and antibacterial breathable layer. Put the raw materials of each layer into the mixer and mix them separately. After metering, feed them into the corresponding extruders. Specifically, use a high-speed mixer at 550 r / min for 20 min. The extruder temperature is 245±5℃.

[0149] In this process, nano-silver and hydroxypropyl dimethylammonium chloride chitosan are uniformly mixed before being added to the PET resin matrix of the antibacterial and breathable layer to form a premix.

[0150] Nanoscale rigid filler masterbatch includes nano-calcium carbonate masterbatch, which can be made from commercially available products.

[0151] Step 2: A 15μm pore size filter is used, and the filter temperature is set at 245±2℃. After each layer of raw material is melted and filtered, it enters the three-layer co-extrusion die for extrusion. The co-extrusion die temperature is 210±2℃. The material is electrostatically adsorbed onto the cold roller to form a cast sheet. The cold roller speed is 25m / min, the temperature is 25℃, and the thickness of the cast sheet is about 780μm.

[0152] Step 3: Under infrared heating, first stretch longitudinally, preheat temperature 75℃, cooling temperature 25℃, setting temperature 40℃, stretching ratio 3.0;

[0153] Then, perform transverse stretching, with a preheating temperature of 100℃, a stretching temperature of 110℃, a setting temperature of 115℃, a cooling temperature of 30℃, and a stretching ratio of 3.2.

[0154] Step 4: Double-sided corona treatment, obtaining corona layers with a thickness of approximately 3μm on both sides, removing static electricity, and winding up;

[0155] Step 5: Unwind the wound film onto the coating line and apply the coating. The preheating temperatures are 40, 45, and 50℃ respectively, and the coating amount is 20g / m². 2 Cool at 25°C, coat the antibacterial breathable layer on the other side of the PET breathable layer to form an adhesive layer, attach the release film, and cut.

[0156] Example 2

[0157] The main difference between this embodiment and Example 1 is that nano-silver / hydroxypropyl dimethylammonium chloride chitosan microspheres are used in the antibacterial breathable layer, which are prepared through the following steps:

[0158] S1. Preparation of silver / chitosan composite microspheres

[0159] S1.1 Prepare 1 mol / L silver nitrate aqueous solution and 0.98 mol / L sodium borohydride aqueous solution respectively;

[0160] S1.2 Add chitosan to an aqueous solution of silver nitrate and stir to obtain a chitosan suspension;

[0161] Under nitrogen protection, the chitosan suspension was heated to 40±1℃, sodium borohydride aqueous solution was added dropwise, the reaction was stirred for 30 min, and then cooled to obtain the nano silver / chitosan complex.

[0162] S1.4 Add glutaraldehyde (glutaraldehyde to chitosan mass ratio is 0.5:100), stir at room temperature for 3 h to obtain nano-silver / chitosan composite microsphere emulsion, centrifuge, wash, and vacuum dry to obtain nano-silver / chitosan composite microspheres.

[0163] S2. Preparation of nano-silver / hydroxypropyl dimethylammonium chloride chitosan composite microspheres

[0164] S2.1 Disperse the nano-silver / chitosan composite microspheres in isopropanol;

[0165] S2.2 Heat to 60℃, add cyclopropyl dimethyl diethyl ammonium chloride isopropanol dropwise, react for 12h, and let stand to separate into layers;

[0166] S2.3 was precipitated by adding anhydrous ethanol, filtered, and dried under vacuum at 65°C to obtain nano-silver / hydroxypropyl dimethyl ammonium chloride chitosan microspheres.

[0167] Example 3

[0168] The difference between this embodiment and Example 2 is that the nano-calcium carbonate masterbatch uses a self-made product, and the finished film has a thickness of approximately 75 μm and a pore size of 180-220 nm. It is prepared through the following steps:

[0169] (1) Preparation of surface-treated nano-calcium carbonate

[0170] (1.1) Disperse CaO in deionized water by ultrasonication to form a Ca(OH)2 slurry with a mass fraction of about 6wt%, let it stand and sieve to remove large particles;

[0171] (1.2) Add polyethylene glycol phosphate, stir for 30 min, and introduce a mixture of CO2 and N2 gas. Stop the reaction at 20℃ when the pH reaches 7, filter, and wash.

[0172] (1.3) Dry in an oven at 80℃ for 10 h to obtain surface-treated nano-calcium carbonate particles;

[0173] (2) Preparation of nano-calcium carbonate masterbatch

[0174] (2.1) Surface-treated nano-calcium carbonate is mixed with ethylene glycol and ultrasonically dispersed; then it is added to the reaction vessel along with terephthalic acid and antimony acetate and stirred and mixed.

[0175] (2.2) Under nitrogen pressure, the temperature was increased to 230℃ at a rate of 4℃ / min to carry out the esterification reaction;

[0176] (2.3) Evacuate to 200 Pa and heat to 268±2℃ for polymerization reaction for 3 h;

[0177] (2.4) Extrusion, water cooling, pelletizing, and drying yield nano-calcium carbonate masterbatch with an ash content of approximately 35%.

[0178] Example 4

[0179] The difference between this embodiment and Embodiment 3 is that the scratch-resistant masterbatch uses polysiloxane abrasion resistant agent AST-50 and carbon nanotubes surface-treated with sodium dodecylbenzene sulfonate in a mass ratio of 4:1, including the following steps:

[0180] (1) Surface treatment of carbon nanotubes, including: preparing a mixed aqueous solution of carbon nanotubes and sodium dodecylbenzenesulfonate, ultrasonically treating it in a water bath for 1-2 hours, filtering it, and vacuum drying it; wherein the mass concentration of carbon nanotubes is 25 g / L and the mass concentration of sodium dodecylbenzenesulfonate is 10 g / L.

[0181] (2) The two scratch-resistant masterbatches are premixed and then added to the breathable wear-resistant layer material.

[0182] The breathable and abrasion-resistant layer, by weight percentage, includes:

[0183]

[0184] Example 5

[0185] This embodiment has the same components as Embodiment 4, the difference being that the thickness of each layer and the total thickness of the film are different.

[0186] The scratch-resistant, antibacterial, and breathable medical film of this embodiment has a thickness of approximately 85 μm and a pore size of 200-350 nm, and comprises, in sequence:

[0187] (1) Breathable and wear-resistant layer, 15μm thick;

[0188] (2) PET breathable layer, 15μm thick;

[0189] (3) Antibacterial and breathable layer, 50μm thick;

[0190] (4) Adhesive layer, on the other side of the antibacterial breathable layer relative to the PET breathable layer, with a thickness of 5μm;

[0191] The main difference in preparation methods is that

[0192] (1) The thickness of the co-extruded cooled casting sheet is approximately 950 μm;

[0193] (2) Longitudinal stretch ratio 3.2;

[0194] (3) Lateral stretching ratio 3.3.

[0195] Comparative Example 1

[0196] The difference between this comparative example and Example 1 is that nano-silver and hydroxypropyl dimethylammonium chloride chitosan were directly added to the PET resin matrix of the antibacterial and breathable layer and mixed.

[0197] Comparative Example 2

[0198] The difference between this comparative example and Example 1 is that nanoscale rigid filler masterbatch is not used, and no compounding resin is added to the matrix resin of the PET breathable layer.

[0199] Comparative Example 3

[0200] The difference between this comparative example and Example 1 is that scratch-resistant masterbatch is not used on the surface.

[0201] Performance testing and methods:

[0202] (1) Air permeability: According to JGJ / T235, water vapor transmission rate was tested at 5 different parts of the same sample and the average value was used for evaluation.

[0203] (2) Permeability: The hydrostatic pressure test was conducted at a water column of 1000 mm.

[0204] (3) Tensile strength: The longitudinal and transverse tensile strength of the film and the mechanical retention rate after immersion in water for 24 hours were tested according to GB / T 328.9-2007.

[0205] (4) Scratch test: Take a 20*20mm film sample and attach it to the sample stage of the steel wool abrasion tester. Place 500g and 1000g load weights on it respectively. Rub the breathable abrasion-resistant layer back and forth for 50 cycles at a speed of 13mm / s. Then use a USB Digital Microscope to observe and compare the area before and after the friction.

[0206] (5) Antibacterial performance test:

[0207] The antibacterial activity of the test membrane samples against *Escherichia coli* and *Staphylococcus aureus* was determined using a bacterial counting method. After diluting the bacterial suspension (10⁵ CFU) with liquid culture medium (PBS buffer), 0.1 g of blank filter paper and 0.1 g of the test membrane sample were added separately, and the mixture was shaken and incubated for 24 h. The incubated bacterial suspension was then diluted 100-fold with phosphate buffer. More than 100 μL of the diluted bacterial solution was evenly spread onto Luria Bertani (LB) agar plates and incubated at 37 °C for 24 h.

[0208] Reduction of bacteria (%) = (a - b) / a × 100% Formula (II);

[0209] In formula (II): a and b are the number of colonies formed when the bacterial solution, which is co-cultured with blank filter paper and the film sample to be tested, is diluted and spread on an agar plate.

[0210] (6) Sustained-release effect test:

[0211] The antibacterial activity of the test membrane samples against *Escherichia coli* and *Staphylococcus aureus* was determined using a bacterial counting method. The bacterial suspension was diluted with liquid culture medium (PBS buffer) (10...). 5 After adding CFU, 0.1 g of blank filter paper and 0.1 g of the membrane sample to be tested were added separately, and the mixture was shaken and incubated for 24 h. The cultured bacterial solution was then diluted 100 times with phosphate buffer solution. More than 100 μL of the diluted bacterial solution was evenly spread on Luria Bertani (LB) agar plates and incubated at 37 °C for 24 h.

[0212] The cultured samples were placed for 0, 15, 30, 45 and 60 days, respectively, and the antibacterial activity of the membrane against Escherichia coli and Staphylococcus aureus was determined by bacterial counting method.

[0213] The test results of Examples 1-5 and Comparative Examples 1-3 are shown in Tables 1 and 2.

[0214] Table 1

[0215]

[0216] Table 2

[0217]

[0218]

[0219] The preferred embodiments of the present invention have been described above to make the spirit of the present invention clearer and easier to understand, and are not intended to limit the present invention. All modifications, substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope summarized by the appended claims.

Claims

1. A scratch-resistant, medical antibacterial, breathable film, characterized in that, The air-permeable wear-resistant layer, the PET air-permeable layer and the antibacterial air-permeable layer are sequentially arranged. The air-permeable wear-resistant layer has a thickness of 10-20 μm and comprises, by weight percentage: PET resin 75-89%; Scratch-resistant masterbatch 5-10%; Lubricating dispersant 0.2-2%; Nanoscale rigid filler masterbatch 5-10%; Auxiliary agent 0.8-3%; The PET air-permeable layer has a thickness of 10-20 μm and comprises, by weight percentage: Base resin 75-85%; Nanoscale rigid filler masterbatch 10-20%; Compatibilizer 2-7%; Auxiliary agent 1-6%; The antibacterial air-permeable layer has a thickness of 30-50 μm and comprises, by weight percentage: PET resin 70-80%; Nano-silver 4-8%; Chitosan quaternary ammonium salt 5-10%; Nanoscale rigid filler masterbatch 5-10%; Auxiliary agent 2-6%; The base resin of the PET air-permeable layer comprises, by weight percentage: PET resin 85-95%; Blending resin 5-15%; The blending resin is selected from at least one of LDPE, copolymerized PP and TPE. The scratch-resistant masterbatch comprises at least one of polysiloxane wear-resistant agent with a molecular weight of 1.2-1.5 million and carbon nanotube surface treated by sodium dodecyl benzene sulfonate. The nanoscale rigid filler masterbatch comprises nanometer calcium carbonate masterbatch. The scratch-resistant medical antibacterial air-permeable film is prepared by co-extrusion and bidirectional stretching, has a film thickness of 70-90 μm and a film pore size of 80-350 nm. In the antibacterial air-permeable layer, the chitosan quaternary ammonium salt is hydroxypropyl dimethyl ammonium chloride chitosan, and the nano-silver and the hydroxypropyl dimethyl ammonium chloride chitosan form nano-silver / hydroxypropyl dimethyl ammonium chloride chitosan composite microspheres, which are prepared by the following steps: S1, preparation of nano-silver / chitosan composite microspheres S1.1, respectively prepare silver nitrate aqueous solution and sodium borohydride aqueous solution; S1.2, add chitosan into the silver nitrate aqueous solution and stir to obtain chitosan suspension; S1.3, under nitrogen protection, heat the chitosan suspension to 35-42℃, drop the sodium borohydride aqueous solution, stir for 20-40 min and cool to obtain nano-silver / chitosan composite; S1.4, add glutaraldehyde, stir at room temperature for 2-5 h to obtain nano-silver / chitosan composite microsphere emulsion, centrifugal separation and washing, vacuum drying to obtain nano-silver / chitosan composite microspheres; S2, preparation of nano-silver / hydroxypropyl dimethyl ammonium chloride chitosan composite microspheres S2.1, disperse the nano-silver / chitosan composite microspheres in isopropyl alcohol; S2.2, heat to 55-65℃, drop epoxypropyl dimethyl diethyl ammonium chloride into isopropyl alcohol, react for 10-15 h and stand for layering; S2.3, add anhydrous ethanol for precipitation, suction filtration and vacuum drying to obtain nano-silver / hydroxypropyl dimethyl ammonium chloride chitosan microspheres.

2. The scratch resistant, medical antibacterial, breathable film of claim 1, wherein, The auxiliary agent of the air-permeable wear-resistant layer, the auxiliary agent of the PET air-permeable layer and / or the auxiliary agent of the antibacterial air-permeable layer comprise at least one of antioxidant, PET nucleating agent, opening agent and color masterbatch.

3. The scratch resistant, medical antibacterial, breathable film of claim 2, wherein, The PET nucleating agent is selected from at least one of inorganic nucleating agent and organic nucleating agent.

4. The scratch resistant, medical antibacterial, breathable film of claim 2, wherein, The opening agent is selected from at least one of micron BaSO4 and SiO2.

5. The scratch resistant, medical antibacterial, breathable film according to any one of claims 1-4, wherein, The nano calcium carbonate master batch is prepared by the following steps: (1) preparing surface-treated nano calcium carbonate (1.1) ultrasonic dispersion of CaO in deionized water to form Ca(OH)2 slurry, and standing and sieving to remove large particles; (1.2) adding a surface treatment agent, stirring, and introducing a CO2 and N2 mixed gas to react at 15-20℃, filtering, and washing; (1.3) drying in an oven at 70-90℃ for 8-15h to obtain surface-treated nano calcium carbonate particles; (2) preparing a nano calcium carbonate master batch (2.1) ultrasonic dispersion of the surface-treated nano calcium carbonate and ethylene glycol, and adding terephthalic acid and antimony acetate into a reaction kettle and stirring; (2.2) esterification at a rate of 3-5℃ / min to 200-250℃ under nitrogen pressure; (2.3) vacuuming to 200-300Pa for 1-3h of polymerization; (2.4) extruding, water-cooling, and pelletizing, and drying to obtain a nano calcium carbonate master batch.

6. The scratch resistant, medical antibacterial, breathable film of claim 5, wherein, The other layer of the antibacterial breathable layer opposite the PET breathable layer further comprises an adhesive layer with a thickness of 5-10μm and containing the following components by weight percentage: adhesive 90-95%; chitosan 0-5%; nano silver 0-5%; the adhesive is selected from at least one of a medical water-based latex and a medical solvent-based glue.

7. The method of claim 1-6, wherein the method is characterized by, The following steps are included: Step one: configuring raw materials of the wear-resistant breathable layer, the PET breathable layer, and the antibacterial breathable layer, respectively feeding the raw materials into a mixer, and then feeding into corresponding extruders after metering; Step two: extruding the raw materials after melting and filtering into a three-layer co-extrusion die head, and electrostatically adsorbing onto a cold roller to form a cast sheet; Step three: first stretching longitudinally, and then stretching transversely; Step four: single-sided or double-sided corona treatment to obtain a corona layer with a thickness of 3-10μm, removing static electricity, and winding; Step five: slitting; or coating an adhesive layer on the other layer of the antibacterial breathable layer opposite the PET breathable layer, attaching a release film, and slitting.

8. The production method according to claim 7, wherein The temperature of the three-layer co-extrusion die head is 200-220℃, the rotation speed of the cold roller is 18-35m / min, the temperature of the cold roller is 20-35℃, the thickness of the cast sheet is 400-950μm, the longitudinal stretching ratio is 2.4-4.0, and the transverse stretching ratio is 2.6-4.0.

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