Degradable modified hydroxy propyl cellulose / polyurethane / Ag-coated NCQDs composite film for antibacterial fresh-keeping material and preparation method of degradable modified hydroxy propyl cellulose / polyurethane / Ag-coated NCQDs composite film
By combining hydroxypropyl cellulose with polyurethane and Ag@NCQDs nanoparticles, a degradable composite film with antibacterial freshness performance was prepared, which solved the problem of difficult degradation of traditional plastics and insufficient antibacterial performance of biodegradable materials, and achieved efficient antibacterial freshness effect.
Patent Information
- Application Number
- CN202510335713.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-20
- Publication Date
- 2025-05-13
AI Technical Summary
Traditional plastic materials are difficult to degrade, resulting in ecological and environmental pollution, and existing biodegradable materials have shortcomings in antibacterial preservation performance.
Using hydroxypropyl cellulose as the base material, it is modified by cross-linking of hexamethylene diisocyanate, and is compounded with polyurethane and Ag@NCQDs nanoparticles. A degradable composite film with antibacterial freshness performance is prepared by solution blending and casting.
The prepared composite membrane has excellent water resistance, high mechanical properties, good biodegradability and excellent antibacterial freshness performance. The antibacterial rate can reach 99.5%, and has a wide market application prospect.
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Figure CN119978485A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of antibacterial fresh-keeping materials, and in particular relates to a degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film for antibacterial fresh-keeping materials and a preparation method thereof. Background Art
[0002] From processing and manufacturing to transportation and preservation, packaging film is essential to maintain product quality and safety. At present, the plastic industry has developed rapidly. Plastic products made of petroleum-based plastic materials, including polystyrene, polypropylene and polyethylene terephthalate, are widely used in various fields of people's lives. The birth of plastics has indeed brought a lot of convenience to people's daily lives. However, with the continuous development of the plastic industry, some hidden dangers have gradually been exposed. Due to the high chemical stability of traditional plastics, they are almost not degraded in nature, which has caused serious ecological problems and brought a heavy burden to the earth's ecological environment. At present, the treatment of traditional plastics is mainly based on incineration and burial, which cannot fundamentally solve the problem of plastic waste pollution and may also cause secondary pollution. Therefore, there is an urgent need to induce new biodegradable and low-toxic biological materials as substitutes. Recently, there has been increasing interest in the development of biodegradable films for packaging materials based on natural polymer components, such as natural biomass materials such as chitosan, cellulose or gelatin (Chen Hongyan. Preparation and properties of bamboo cellulose reinforced composite films [J]. Journal of China Agricultural University, 2019, 24(12): 121-127.). Due to their good biodegradability, biotoxicity and film-forming properties, they are considered as biomaterials in the fields of biomedical engineering, food packaging, cosmetics and agriculture. Currently, biodegradable plastics can be divided into: (1) chemically synthesized degradable plastics, such as aliphatic polyesters such as polylactic acid (PLA), polyhydroxyvalerate (PHV), and polycaprolactone (PCL). (2) Plastics synthesized by microorganisms, namely microbial polyesters. (3) Natural polymer plastics, that is, natural polymers that are biodegradable and have good physical properties, such as cellulose, chitin, starch, protein, etc. as substitutes for plastics. (4) Filled plastics, that is, partially degradable plastics obtained by blending natural polymers with synthetic resins. At present, the research on natural polymer-filled composite plastics has gradually attracted people's attention and has great development prospects in the field of biodegradable materials (Sun Haojiong et al. Preparation and properties of PMMA / cotton cellulose composite films [J]. Engineering Plastics Application, 2021, 49 (1): 34-39.). Cellulose, as the most abundant natural polymer in nature, has the advantages of wide sources, low prices, and easy biodegradation. Therefore, when cellulose is mixed with other polymers to form a film, many unique properties can be obtained, thereby enhancing the value of cellulose-based film materials in practical applications. Polyurethane is biodegradable and biocompatible, and has good antiseptic, antibacterial, and film-forming properties. It is used as a biomedical material and degradable packaging material. In addition, microorganisms can cause food to deteriorate, so packaging films with antibacterial and fresh-keeping properties have become popular recently. Some food packaging films can even release bactericides to delay the decay of microorganisms and extend the shelf life.Functional materials that can extend shelf life, detect additives, and sense food quality have great potential in the food industry.
[0003] It can be seen that the modification of cellulose and its combination with other biodegradable polymers can not only increase the film-forming property and mechanical strength of cellulose membranes, but also further realize the multifunctionality of cellulose-based composite membrane materials. Cellulose composite membrane materials with excellent mechanical properties and antibacterial and fresh-keeping properties have great development prospects. Summary of the invention
[0004] The purpose of the present invention is to solve the above problems, such as Figure 4 As shown in the figure, a degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film for antibacterial preservation material was prepared by solution blending and casting, using hydroxypropyl cellulose as the base material, hexamethylene diisocyanate as the cross-linking agent, polyurethane as the composite material, and Ag@NGQDs nanoparticle solution as the additive. The operation steps are relatively simple, and the prepared composite film has excellent water resistance, high mechanical properties, good biodegradability and good antibacterial preservation properties, and has market application prospects.
[0005] In order to achieve the above object, the present invention adopts the following technical solutions:
[0006] The technical solution of the present invention is implemented according to the following steps:
[0007] A method for preparing a degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film for antibacterial and fresh-keeping materials, characterized in that it comprises the following steps:
[0008] (1) Preparation of N-doped carbon quantum dot solution, i.e., NCQDs solution: citric acid and arginine were mixed and placed in a beaker for heating, poured into distilled water for dissolution, and filtered to prepare NCQDs solution;
[0009] (2) Preparation of Ag@NCQDs nanoparticle solution: AgNO3 solution was mixed with the NCQDs solution in step (1), and magnetic stirring was performed to obtain Ag@NCQDs nanoparticle solution;
[0010] (3) Preparation of modified hydroxypropyl cellulose solution: hydroxypropyl cellulose is added to N,N-dimethylformamide to dissolve, and then hexamethylene diisocyanate is added dropwise and stirred to obtain a modified hydroxypropyl cellulose solution;
[0011] (4) Preparation of modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs film-forming solution: adding the polyurethane solution to the modified hydroxypropyl cellulose solution of step (3), stirring evenly, and then adding the Ag@NCQDs nanoparticle solution of step (2), and continuing to stir to obtain a modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs film-forming solution;
[0012] (5) Preparation of degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite membrane: introducing the modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs film-forming solution of step (4) into a mold and drying it to form a film, thereby obtaining a modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite membrane;
[0013] (6) Cutting and sealing the degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film in step (5) to use it as an antibacterial fresh-keeping material.
[0014] The specific method for preparing the NCQDs solution in step (1) is as follows: 5 to 10 parts of citric acid and 0.1 to 1 part of arginine are put into a beaker, stirred and mixed evenly, and heated at 180 to 200° C. in contact with air for 10 to 30 minutes to fully react; then, while hot, poured into 50 parts of distilled water, stirred at room temperature in contact with air for 20 to 30 minutes to dissolve; filtered at 1 mL / min using a 0.22 μm filter membrane and a 10 mL syringe, and the obtained light yellow filtrate is the NCQDs solution.
[0015] The specific method for preparing the Ag@NCQDs nanoparticle solution in step (2) is to mix 0.001 to 0.006 parts of 0.1 mol / L AgNO3 solution with 2 to 10 parts of NCQDs solution, expose them to air at room temperature, and stir them magnetically at 300 rpm for 5 to 10 hours to obtain the Ag@NCQDs nanoparticle solution.
[0016] The specific method for preparing the modified hydroxypropyl cellulose solution in step (3) is as follows: 0.2-1.0 parts of hydroxypropyl cellulose are added to 15-20 parts of N,N-dimethylformamide, exposed to air at 20-30°C, and magnetically stirred at 500 rpm for 30-60 min to fully dissolve the hydroxypropyl cellulose; then 0.01-0.1 parts of hexamethylene diisocyanate are added dropwise at a rate of 20 drops / min, and magnetically stirred at 500 rpm for 1 h to obtain the modified hydroxypropyl cellulose solution.
[0017] The relative molecular weight of the hydroxypropyl cellulose hydroxyl group in the step (3) is 50,000 to 200,000.
[0018] The specific method for preparing the modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs film-forming solution in the step (4) is as follows: 0.2 to 1.0 parts of a 30 wt% polyurethane solution are added to 15 to 20 parts of a modified hydroxypropyl cellulose solution, exposed to air at room temperature, and magnetically stirred at 500 rp for 20 to 40 minutes; then 0.1 to 1 parts of an Ag@NCQDs nanoparticle solution are added, and magnetic stirring at 500 rp is continued for 20 to 40 minutes to obtain a modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs film-forming solution.
[0019] The drying and film-forming conditions in the step (5) are to pre-set the temperature of the mold heating table, maintain the mold temperature at 50-60°C, and directly peel off the film after drying to obtain a degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film with a thickness of 0.5-1.5 mm and a smooth surface.
[0020] The material of the filter membrane is polyethersulfone, polytetrafluoroethylene, nylon or polyvinylidene fluoride.
[0021] The polyurethane solution is an aqueous solution, and the relative molecular weight of the polyurethane is 10,000-50,000.
[0022] A degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film was prepared for antibacterial and fresh-keeping materials.
[0023] The present invention has the following beneficial effects: the present invention provides a method for preparing a degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film for antibacterial fresh-keeping materials, using hydroxypropyl cellulose as a base material, cross-linking and modifying hydroxypropyl cellulose with hexamethylene diisocyanate to increase the water resistance of the hydroxypropyl cellulose film, using polyurethane as a composite material, and using green and antibacterial Ag@NCQDs as an additive, and obtaining a degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film with high mechanical properties, water resistance, environmental friendliness and fresh-keeping antibacterial properties by compounding modified hydroxypropyl cellulose with polyurethane and Ag@NCQDs antibacterial additives, the tensile strength can reach 59.3MPa, and the antibacterial ability can reach 99.5%. In addition, the raw materials used are widely available and low in price, and the preparation process is green, environmentally friendly and relatively simple, thereby improving productivity and further reducing production costs, and having good market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0025] Figure 1 Schematic diagram of the preparation process of NCQDs.
[0026] Figure 2 This is the particle size distribution diagram of NCQDs in NCQDs solution.
[0027] Figure 3 Schematic diagram of the preparation process of Ag@NCQDs.
[0028] Figure 4 Schematic diagram of the preparation process of modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite membrane.
[0029] Figure 5 Infrared spectra of hydroxypropyl cellulose, modified hydroxypropyl cellulose, polyurethane, modified hydroxypropyl cellulose / polyurethane composite film and modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film.
[0030] Figure 6 This is a comparison chart of the tensile strength of hydroxypropyl cellulose membrane, modified hydroxypropyl cellulose membrane, modified hydroxypropyl cellulose / polyurethane composite membrane and modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite membrane. DETAILED DESCRIPTION
[0031] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0032] Example 1
[0033] A method for preparing a degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film for antibacterial and fresh-keeping materials, characterized in that it comprises the following steps:
[0034] (1) Preparation of N-doped carbon quantum dot solution, i.e., NCQDs solution: citric acid and arginine were mixed and placed in a beaker for heating, poured into distilled water for dissolution, and filtered to prepare NCQDs solution;
[0035] (2) Preparation of Ag@NCQDs nanoparticle solution: AgNO3 solution was mixed with the NCQDs solution in step (1), and magnetic stirring was performed to obtain Ag@NCQDs nanoparticle solution;
[0036] (3) Preparation of modified hydroxypropyl cellulose solution: hydroxypropyl cellulose is added to N,N-dimethylformamide to dissolve, and then hexamethylene diisocyanate is added dropwise and stirred to obtain a modified hydroxypropyl cellulose solution;
[0037] (4) Preparation of modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs film-forming solution: adding the polyurethane solution to the modified hydroxypropyl cellulose solution of step (3), stirring evenly, and then adding the Ag@NCQDs nanoparticle solution of step (2), and continuing to stir to obtain a modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs film-forming solution;
[0038] (5) Preparation of degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite membrane: introducing the modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs film-forming solution of step (4) into a mold and drying it to form a film, thereby obtaining a modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite membrane;
[0039] (6) Cutting and sealing the degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film in step (5) to use it as an antibacterial fresh-keeping material.
[0040] The specific method for preparing the NCQDs solution in step (1) is to put 5 parts of citric acid and 0.1 parts of arginine into a beaker and stir and mix them evenly. The reaction process is as follows: Figure 1 As shown, the mixture was heated at 180°C in contact with air for 10 to 30 minutes to fully react; then, it was poured into 50 parts of distilled water while hot and stirred at room temperature for 20 minutes to dissolve in contact with air; large particles were filtered out using a 0.22 μm polytetrafluoroethylene filter membrane and a 10 mL syringe at 1 mL / min to remove large particles. The light yellow filtrate obtained was the NCQDs solution. The particle size distribution of NCQDs is shown in Figure 2 As shown, the average particle size of NCQDs is about 8 nm.
[0041] The specific method for preparing the Ag@NCQDs nanoparticle solution in step (2) is to mix 0.001 parts of 0.1 mol / L AgNO3 solution with 2 parts of NCQDs solution, and the reaction process is as follows: Figure 3 As shown, the Ag@NCQDs nanoparticle solution was obtained by exposing it to air at room temperature and magnetically stirring it at 300 rpm for 5 h.
[0042] The specific method for preparing the modified hydroxypropyl cellulose solution in step (3) is as follows: 0.2 parts of hydroxypropyl cellulose with a relative molecular weight of 50,000 is added to 15 parts of N,N-dimethylformamide, exposed to air at 20°C, and magnetically stirred at 500 rpm for 30 minutes to fully dissolve the hydroxypropyl cellulose; then 0.01 parts of hexamethylene diisocyanate are added dropwise at a rate of 20 drops / min, and magnetically stirred at 500 rpm for 1 hour to obtain the modified hydroxypropyl cellulose solution.
[0043] The specific method for preparing the modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs film-forming solution in the step (4) is as follows: 0.2 parts of a 30wt% polyurethane solution with a relative molecular mass of 10,000 are added to 15 parts of a modified hydroxypropyl cellulose solution, exposed to air at room temperature, and magnetically stirred at 500rp for 20 minutes; then 0.1 parts of an Ag@NCQDs nanoparticle solution are added, and magnetic stirring at 500rp is continued for 20 minutes to obtain a modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs film-forming solution.
[0044] The drying and film-forming conditions in the step (5) are to pre-set the temperature of the mold heating table, maintain the mold temperature at 50°C, and directly peel off the film after drying to obtain a degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film with a thickness of 0.5 mm and a smooth surface.
[0045] The degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film was cut and sealed to be used as an antibacterial preservation material.
[0046] from Figure 5 The infrared spectrum of the modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film shown in Figure 2 shows that 2916 cm -1 The peak at 1662cm is the stretching vibration of -CH in the hydroxypropyl cellulose structure. The peak increases here, indicating that more CH2 is introduced after the cross-linking modification of hexamethylene isocyanate, so the stretching vibration of -CH is enhanced; -1 The peak at is the stretching vibration peak of the polyurethane amide ester bond, indicating that polyurethane and modified hydroxypropyl cellulose can be well composited; in summary, it can be seen that the preparation of modified hydroxypropyl cellulose membrane / polyurethane membrane / Ag@NCQDs composite membrane is successful.
[0047] The prepared biodegradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film for antibacterial preservation materials was cut into rectangular blocks with a length and width of 5 cm×1 cm. The initial distance between the clamps was 25 mm, the stretching speed was 1 mm / s, the return speed was 10 mm / s, and each group of samples was paralleled five times. The calculation formula is as follows: tensile strength TS=F / D×d, where D is the width of the film (mm) and d is the thickness of the film (mm). Figure 6 As shown, the maximum tensile strength of the modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite membrane is 59.3 MPa; while the maximum tensile strengths of the control hydroxypropyl cellulose membrane, modified hydroxypropyl cellulose membrane, and modified hydroxypropyl cellulose / polyurethane membrane obtained under the same test conditions are 19.7 MPa, 20.5 MPa, and 45.2 MPa, respectively.
[0048] Referring to the standard QB / T 2591-2003 "Antibacterial Plastics - Test Methods for Antibacterial Performance and Antibacterial Effects" and the 2002 "Technical Specifications for Disinfection" of the Ministry of Health of the People's Republic of China, the prepared degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film for antibacterial preservation materials was allowed to react with a certain amount of bacterial suspension for a period of time, cultured, and then the colonies were counted.
[0049] Purchase fresh strawberries of uniform size and group them, place the strawberries in a plastic tray, and then seal them with a hydroxypropyl cellulose film and a degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film for antibacterial fresh-keeping materials of the present invention. Test the decay index of different storage times respectively. Determination of the decay index: First, grade the strawberries according to the degree of decay. Grade 0: fresh strawberries without decay or damage; Grade 1: fruits with rotten spots less than 1 / 4 of the strawberry area; Grade 2: fruits with rotten spots greater than 1 / 4 but less than 1 / 2 of the strawberry area; Grade 3: fruits with rotten spots greater than 1 / 2 but less than 3 / 4 of the strawberry area; Grade 4: fruits with rotten spots greater than 3 / 4 of the strawberry area. Rot index = (∑ number of levels × number of strawberries at this level) / total number of strawberries tested. As shown in Table 1, the antibacterial rate of the modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film of this embodiment is 99.3%, and the decay index is level 0, while the antibacterial rate and decay index of the control example are 15.8 and level 2, respectively. The modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film of the present invention has excellent antibacterial and fresh-keeping properties.
[0050] Table 1 Comparison of antibacterial and fresh-keeping properties of the modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film prepared by the present invention and the hydroxypropyl cellulose film
[0051] Example Antibacterial rate (%) Decay Index Example 1 99.3 Level 0 Example 2 96.3 Level 0 Example 3 98.6 Level 0 Example 4 99.5 Level 0 Comparison example 15.8 Level 2
[0052] Example 2
[0053] A method for preparing a degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film for antibacterial and fresh-keeping materials, characterized in that it comprises the following steps:
[0054] (1) Preparation of N-doped carbon quantum dot solution, i.e., NCQDs solution: citric acid and arginine were mixed and placed in a beaker for heating, poured into distilled water for dissolution, and filtered to prepare NCQDs solution;
[0055] (2) Preparation of Ag@NCQDs nanoparticle solution: AgNO3 solution was mixed with the NCQDs solution in step (1), and magnetic stirring was performed to obtain Ag@NCQDs nanoparticle solution;
[0056] (3) Preparation of modified hydroxypropyl cellulose solution: hydroxypropyl cellulose is added to N,N-dimethylformamide to dissolve, and then hexamethylene diisocyanate is added dropwise and stirred to obtain a modified hydroxypropyl cellulose solution;
[0057] (4) Preparation of modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs film-forming solution: adding the polyurethane solution to the modified hydroxypropyl cellulose solution of step (3), stirring evenly, and then adding the Ag@NCQDs nanoparticle solution of step (2), and continuing to stir to obtain a modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs film-forming solution;
[0058] (5) Preparation of degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite membrane: introducing the modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs film-forming solution of step (4) into a mold and drying it to form a film, thereby obtaining a modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite membrane;
[0059] (6) Cutting and sealing the degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film in step (5) to use it as an antibacterial fresh-keeping material.
[0060] The specific method for preparing the NCQDs solution in step (1) is as follows: 6 parts of citric acid and 0.2 parts of arginine are put into a beaker, stirred and mixed evenly, and heated at 185°C for 20 minutes in contact with air for sufficient reaction; then poured into 50 parts of distilled water while hot, and stirred at room temperature for 20 minutes in contact with air for dissolution; large particles are filtered out at 1 mL / min using a 0.22 μm polyethersulfone filter membrane and a 10 mL syringe, and the obtained light yellow filtrate is the NCQDs solution.
[0061] The specific method for preparing the Ag@NCQDs nanoparticle solution in step (2) is to mix 0.002 parts of 0.1 mol / L AgNO3 solution with 4 parts of NCQDs solution, expose them to air at room temperature, and stir them magnetically at 300 rpm for 6 hours to obtain the Ag@NCQDs nanoparticle solution.
[0062] The specific method for preparing the modified hydroxypropyl cellulose solution in step (3) is as follows: 0.4 parts of hydroxypropyl cellulose with a relative molecular weight of 80,000 is added to 16 parts of N,N-dimethylformamide, exposed to air at 25°C, and magnetically stirred at 500 rpm for 40 minutes to fully dissolve the hydroxypropyl cellulose; then 0.02 parts of hexamethylene diisocyanate are added dropwise at a rate of 20 drops / min, and magnetically stirred at 500 rpm for 1 hour to obtain the modified hydroxypropyl cellulose solution.
[0063] The specific method for preparing the modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs film-forming solution in the step (4) is as follows: 0.4 parts of a 30wt% polyurethane solution with a relative molecular mass of 20,000 are added to 16 parts of a modified hydroxypropyl cellulose solution, exposed to air at room temperature, and magnetically stirred at 500rp for 25 minutes; then 0.2 parts of an Ag@NCQDs nanoparticle solution are added, and magnetic stirring at 500rp is continued for 20 minutes to obtain a modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs film-forming solution.
[0064] The drying and film-forming conditions in the step (5) are to pre-set the temperature of the mold heating table, maintain the mold temperature at 55°C, and directly peel off the film after drying to obtain a degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film with a thickness of 0.8 mm and a smooth surface.
[0065] The degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film was cut and sealed to be used as an antibacterial preservation material.
[0066] The prepared degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film for antibacterial preservation materials was cut into rectangular blocks with a length and width of 5cm×1cm. The initial distance between the clamps was 25mm, the stretching speed was 1mm / s, the return speed was 10mm / s, and each group of samples was paralleled five times. The calculation formula is as follows: tensile strength TS=F / D×d, where D is the width of the film (mm) and d is the thickness of the film (mm). The maximum tensile strength of the modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film is 56.3MPa; while the maximum tensile strengths of the control hydroxypropyl cellulose film, modified hydroxypropyl cellulose film, and modified hydroxypropyl cellulose / polyurethane film obtained under the same test conditions are 19.7MPa, 20.5MPa, and 45.2MPa, respectively.
[0067] Referring to the standard QB / T 2591-2003 "Antibacterial Plastics - Test Methods for Antibacterial Performance and Antibacterial Effects" and the 2002 "Technical Specifications for Disinfection" of the Ministry of Health of the People's Republic of China, the prepared degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film for antibacterial preservation materials was allowed to react with a certain amount of bacterial suspension for a period of time, cultured, and then the colonies were counted.
[0068] Purchase fresh strawberries of uniform size and group them, place the strawberries in a plastic tray, and then seal them with a hydroxypropyl cellulose film and a degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film for antibacterial fresh-keeping materials of the present invention. Test the decay index of different storage times respectively. Determination of the decay index: First, grade the strawberries according to the degree of decay. Grade 0: fresh strawberries without decay and damage; Grade 1: fruits with rotten spots less than 1 / 4 of the strawberry area; Grade 2: fruits with rotten spots greater than 1 / 4 but less than 1 / 2 of the strawberry area; Grade 3: fruits with rotten spots greater than 1 / 2 but less than 3 / 4 of the strawberry area; Grade 4: fruits with rotten spots greater than 3 / 4 of the strawberry area. Rot index = (∑ number of levels × number of strawberries at this level) / total number of strawberries tested. As shown in Table 1, the antibacterial rate of the modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film of this embodiment is 96.3%, and the decay index is grade 0.
[0069] Example 3
[0070] A method for preparing a degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film for antibacterial and fresh-keeping materials, characterized in that it comprises the following steps:
[0071] (1) Preparation of N-doped carbon quantum dot solution, i.e., NCQDs solution: citric acid and arginine were mixed and placed in a beaker for heating, poured into distilled water for dissolution, and filtered to prepare NCQDs solution;
[0072] (2) Preparation of Ag@NCQDs nanoparticle solution: AgNO3 solution was mixed with the NCQDs solution in step (1), and magnetic stirring was performed to obtain Ag@NCQDs nanoparticle solution;
[0073] (3) Preparation of modified hydroxypropyl cellulose solution: hydroxypropyl cellulose is added to N,N-dimethylformamide to dissolve, and then hexamethylene diisocyanate is added dropwise and stirred to obtain a modified hydroxypropyl cellulose solution;
[0074] (4) Preparation of modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs film-forming solution: adding the polyurethane solution to the modified hydroxypropyl cellulose solution of step (3), stirring evenly, and then adding the Ag@NCQDs nanoparticle solution of step (2), and continuing to stir to obtain a modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs film-forming solution;
[0075] (5) Preparation of degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite membrane: introducing the modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs film-forming solution of step (4) into a mold and drying it to form a film, thereby obtaining a modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite membrane;
[0076] (6) Cutting and sealing the degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film in step (5) to use it as an antibacterial fresh-keeping material.
[0077] The specific method for preparing the NCQDs solution in step (1) is as follows: 8 parts of citric acid and 0.6 parts of arginine are put into a beaker, stirred and mixed evenly, and heated at 195°C for 10 minutes in contact with air for a full reaction; then poured into 50 parts of distilled water while hot, and stirred at room temperature for 15 minutes in contact with air for dissolution; large particles are filtered out at 1 mL / min using a 0.22 μm nylon 1212 filter membrane and a 10 mL syringe, and the obtained light yellow filtrate is the NCQDs solution.
[0078] The specific method for preparing the Ag@NCQDs nanoparticle solution in step (2) is to mix 0.004 parts of 0.1 mol / L AgNO3 solution and 8 parts of NCQDs solution evenly, expose to air at room temperature, and stir magnetically at 300 rpm for 8 hours to obtain the Ag@NCQDs nanoparticle solution.
[0079] The specific method for preparing the modified hydroxypropyl cellulose solution in step (3) is as follows: 0.8 parts of hydroxypropyl cellulose with a relative molecular weight of 100,000 is added to 18 parts of N,N-dimethylformamide, exposed to air at 30°C, and magnetically stirred at 500 rpm for 45 minutes to fully dissolve the hydroxypropyl cellulose; then 0.04 parts of hexamethylene diisocyanate are added dropwise at a rate of 20 drops / min, and magnetically stirred at 500 rpm for 1 hour to obtain the modified hydroxypropyl cellulose solution.
[0080] The specific method for preparing the modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs film-forming solution in the step (4) is as follows: 0.6 parts of a 30wt% polyurethane solution with a relative molecular mass of 30,000 are added to 18 parts of a modified hydroxypropyl cellulose solution, exposed to air at room temperature, and magnetically stirred at 500rp for 35 minutes; then 0.4 parts of an Ag@NCQDs nanoparticle solution are added, and magnetic stirring at 500rp is continued for 30 minutes to obtain a modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs film-forming solution.
[0081] The drying and film-forming conditions in the step (5) are to pre-set the temperature of the mold heating table, maintain the mold temperature at 58°C, and directly peel off the film after drying to obtain a degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film with a thickness of about 1.0 mm and a smooth surface.
[0082] The degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film was cut and sealed to be used as an antibacterial preservation material.
[0083] The prepared degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film for antibacterial preservation materials was cut into rectangular blocks with a length and width of 5cm×1cm. The initial distance between the clamps was 25mm, the stretching speed was 1mm / s, the return speed was 10mm / s, and each group of samples was paralleled five times. The calculation formula is as follows: tensile strength TS=F / D×d, where D is the width of the film (mm) and d is the thickness of the film (mm). The maximum tensile strength of the modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film is 58.6MPa; while the maximum tensile strengths of the control hydroxypropyl cellulose film, modified hydroxypropyl cellulose film, and modified hydroxypropyl cellulose / polyurethane film obtained under the same test conditions are 19.7MPa, 20.5MPa, and 45.2MPa, respectively.
[0084] Referring to the standard QB / T 2591-2003 "Antibacterial Plastics - Test Methods for Antibacterial Performance and Antibacterial Effects" and the 2002 "Technical Specifications for Disinfection" of the Ministry of Health of the People's Republic of China, the prepared degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film for antibacterial preservation materials was allowed to react with a certain amount of bacterial suspension for a period of time, cultured, and then the colonies were counted.
[0085] Purchase fresh strawberries of uniform size and group them, place the strawberries in a plastic tray, and then seal them with a hydroxypropyl cellulose film and a degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film for antibacterial fresh-keeping materials of the present invention. Test the decay index of different storage times respectively. Determination of the decay index: First, grade the strawberries according to the degree of decay. Grade 0: fresh strawberries without decay and damage; Grade 1: fruits with rotten spots less than 1 / 4 of the strawberry area; Grade 2: fruits with rotten spots greater than 1 / 4 but less than 1 / 2 of the strawberry area; Grade 3: fruits with rotten spots greater than 1 / 2 but less than 3 / 4 of the strawberry area; Grade 4: fruits with rotten spots greater than 3 / 4 of the strawberry area. Rot index = (∑ number of levels × number of strawberries at this level) / total number of strawberries tested. As shown in Table 1, the antibacterial rate of the modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film of this embodiment is 98.6%, and the decay index is grade 0.
[0086] Example 4
[0087] A method for preparing a degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film for antibacterial and fresh-keeping materials, characterized in that it comprises the following steps:
[0088] (1) Preparation of N-doped carbon quantum dot solution, i.e., NCQDs solution: citric acid and arginine were mixed and placed in a beaker for heating, poured into distilled water for dissolution, and filtered to prepare NCQDs solution;
[0089] (2) Preparation of Ag@NCQDs nanoparticle solution: AgNO3 solution was mixed with the NCQDs solution in step (1), and magnetic stirring was performed to obtain Ag@NCQDs nanoparticle solution;
[0090] (3) Preparation of modified hydroxypropyl cellulose solution: hydroxypropyl cellulose is added to N,N-dimethylformamide to dissolve, and then hexamethylene diisocyanate is added dropwise and stirred to obtain a modified hydroxypropyl cellulose solution;
[0091] (4) Preparation of modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs film-forming solution: adding the polyurethane solution to the modified hydroxypropyl cellulose solution of step (3), stirring evenly, and then adding the Ag@NCQDs nanoparticle solution of step (2), and continuing to stir to obtain a modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs film-forming solution;
[0092] (5) Preparation of degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite membrane: introducing the modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs film-forming solution of step (4) into a mold and drying it to form a film, thereby obtaining a modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite membrane;
[0093] (6) Cutting and sealing the degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film in step (5) to use it as an antibacterial fresh-keeping material.
[0094] The specific method for preparing the NCQDs solution in step (1) is as follows: 10 parts of citric acid and 1.0 part of arginine are put into a beaker, stirred and mixed evenly, and heated at 200°C for 30 minutes in contact with air for sufficient reaction; then poured into 50 parts of distilled water while hot, and stirred at room temperature for 30 minutes in contact with air for dissolution; large particles are filtered out at 1 mL / min using a 0.22 μm polyvinylidene fluoride filter membrane and a 10 mL syringe, and the obtained light yellow filtrate is the NCQDs solution.
[0095] The specific method for preparing the Ag@NCQDs nanoparticle solution in step (2) is to mix 0.006 parts of 0.1 mol / L AgNO3 solution and 10 parts of NCQDs solution evenly, expose to air at room temperature, and stir magnetically at 300 rpm for 10 hours to obtain the Ag@NCQDs nanoparticle solution.
[0096] The specific method for preparing the modified hydroxypropyl cellulose solution in step (3) is as follows: 1.0 part of hydroxypropyl cellulose with a relative molecular weight of 200,000 is added to 20 parts of N,N-dimethylformamide, exposed to air at 30°C, and magnetically stirred at 500 rpm for 60 minutes to fully dissolve the hydroxypropyl cellulose; then 0.1 part of hexamethylene diisocyanate is added dropwise at a rate of 20 drops / min, and magnetically stirred at 500 rpm for 1 hour to obtain the modified hydroxypropyl cellulose solution.
[0097] The specific method for preparing the modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs film-forming solution in the step (4) is as follows: 1.0 part of a 30wt% polyurethane solution with a relative molecular mass of 50,000 is added to 20 parts of a modified hydroxypropyl cellulose solution, exposed to air at room temperature, and magnetically stirred at 500rp for 40 minutes; then 1.0 part of an Ag@NCQDs nanoparticle solution is added, and magnetic stirring at 500rp is continued for 40 minutes to obtain a modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs film-forming solution.
[0098] The drying and film-forming conditions in the step (5) are to pre-set the temperature of the mold heating table, maintain the mold temperature at 60°C, and directly peel off the film after drying to obtain a degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film with a thickness of 1.5 mm and a smooth surface.
[0099] The degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film was cut and sealed to be used as an antibacterial preservation material.
[0100] The prepared degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film for antibacterial preservation materials was cut into rectangular blocks with a length and width of 5cm×1cm. The initial distance between the clamps was 25mm, the stretching speed was 1mm / s, the return speed was 10mm / s, and each group of samples was paralleled five times. The calculation formula is as follows: tensile strength TS=F / D×d, where D is the width of the film (mm) and d is the thickness of the film (mm). The maximum tensile strength of the modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film is 57.3MPa; while the maximum tensile strengths of the control hydroxypropyl cellulose film, modified hydroxypropyl cellulose film, and modified hydroxypropyl cellulose / polyurethane film obtained under the same test conditions are 19.7MPa, 20.5MPa, and 45.2MPa, respectively.
[0101] Referring to the standard QB / T 2591-2003 "Antibacterial Plastics - Test Methods for Antibacterial Performance and Antibacterial Effects" and the 2002 "Technical Specifications for Disinfection" of the Ministry of Health of the People's Republic of China, the prepared degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film for antibacterial preservation materials was allowed to react with a certain amount of bacterial suspension for a period of time, cultured, and then the colonies were counted.
[0102] Purchase fresh strawberries of uniform size and group them, place the strawberries in a plastic tray, and then seal them with a hydroxypropyl cellulose film and a degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film for antibacterial fresh-keeping materials of the present invention. Test the decay index of different storage times respectively. Determination of the decay index: First, grade the strawberries according to the degree of decay. Grade 0: Fresh strawberries without decay and damage; Grade 1: Fruits with rotten spots less than 1 / 4 of the strawberry area; Grade 2: Fruits with rotten spots greater than 1 / 4 but less than 1 / 2 of the strawberry area; Grade 3: Fruits with rotten spots greater than 1 / 2 but less than 3 / 4 of the strawberry area; Grade 4: Fruits with rotten spots greater than 3 / 4 of the strawberry area. Rot index = (∑ number of levels × number of strawberries at this level) / total number of strawberries tested. As shown in Table 1, the antibacterial rate of the modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film of this embodiment is 99.5%, and the decay index is grade 0.
[0103] The embodiments of the present invention described above and shown in the accompanying drawings should not be interpreted as limiting the technical ideas of the present invention. The protection scope of the present invention is limited only by the contents recorded in the claims, and those skilled in the art can change and modify the technical ideas of the present invention in various forms. Therefore, it is obvious to those skilled in the art that such improvements and modifications will fall within the protection scope of the present invention.
Claims
1. A method for preparing a degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film for antibacterial and fresh-keeping materials, characterized in that: The following steps are involved: (1) Preparation of N-doped carbon quantum dot solution, i.e., NCQDs solution: citric acid and arginine were mixed and placed in a beaker for heating, poured into distilled water for dissolution, and filtered to prepare NCQDs solution; (2) Preparation of Ag@NCQDs nanoparticle solution: AgNO3 solution was mixed with the NCQDs solution in step (1), and magnetic stirring was performed to obtain Ag@NCQDs nanoparticle solution; (3) Preparation of modified hydroxypropyl cellulose solution: hydroxypropyl cellulose is added to N,N-dimethylformamide to dissolve, and then hexamethylene diisocyanate is added dropwise and stirred to obtain a modified hydroxypropyl cellulose solution; (4) Preparation of modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs film-forming solution: adding the polyurethane solution to the modified hydroxypropyl cellulose solution of step (3), stirring evenly, and then adding the Ag@NCQDs nanoparticle solution of step (2), and continuing to stir to obtain a modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs film-forming solution; (5) Preparation of degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite membrane: introducing the modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs film-forming solution of step (4) into a mold and drying it to form a film, thereby obtaining a modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite membrane; (6) Cutting and sealing the degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film in step (5) to use it as an antibacterial fresh-keeping material.
2. The method for preparing a degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film for antibacterial and fresh-keeping materials according to claim 1, characterized in that: The specific method for preparing the NCQDs solution in step (1) is as follows: 5 to 10 parts of citric acid and 0.1 to 1 part of arginine are put into a beaker, stirred and mixed evenly, and heated at 180 to 200° C. in contact with air for 10 to 30 minutes to fully react; then, while hot, poured into 50 parts of distilled water, stirred at room temperature in contact with air for 20 to 30 minutes to dissolve; filtered at 1 mL / min using a 0.22 μm filter membrane and a 10 mL syringe, and the obtained light yellow filtrate is the NCQDs solution.
3. The method for preparing a degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film for antibacterial and fresh-keeping materials according to claim 1, characterized in that: The specific method for preparing the Ag@NCQDs nanoparticle solution in step (2) is to mix 0.001 to 0.006 parts of 0.1 mol / L AgNO3 solution with 2 to 10 parts of NCQDs solution, expose them to air at room temperature, and stir them magnetically at 300 rpm for 5 to 10 hours to obtain the Ag@NCQDs nanoparticle solution.
4. The method for preparing a degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film for antibacterial and fresh-keeping materials according to claim 1, characterized in that: The specific method for preparing the modified hydroxypropyl cellulose solution in step (3) is as follows: 0.2-1.0 parts of hydroxypropyl cellulose are added to 15-20 parts of N,N-dimethylformamide, exposed to air at 20-30°C, and magnetically stirred at 500 rpm for 30-60 min to fully dissolve the hydroxypropyl cellulose; then 0.01-0.1 parts of hexamethylene diisocyanate are added dropwise at a rate of 20 drops / min, and magnetically stirred at 500 rpm for 1 h to obtain the modified hydroxypropyl cellulose solution.
5. The method for preparing a degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film for antibacterial and fresh-keeping materials according to claim 1, characterized in that: The relative molecular weight of the hydroxypropyl cellulose hydroxyl group in the step (3) is 50,000 to 200,000.
6. The method for preparing a degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film for antibacterial and fresh-keeping materials according to claim 1, characterized in that: The specific method for preparing the modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs film-forming solution in the step (4) is as follows: 0.2 to 1.0 parts of a 30 wt% polyurethane solution are added to 15 to 20 parts of a modified hydroxypropyl cellulose solution, exposed to air at room temperature, and magnetically stirred at 500 rp for 20 to 40 minutes; then 0.1 to 1 parts of an Ag@NCQDs nanoparticle solution are added, and magnetic stirring at 500 rp is continued for 20 to 40 minutes to obtain a modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs film-forming solution.
7. The method for preparing a degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film for antibacterial and fresh-keeping materials according to claim 1, characterized in that: The drying and film-forming conditions in the step (5) are to pre-set the temperature of the mold heating table, maintain the mold temperature at 50-60°C, and directly peel off the film after drying to obtain a degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film with a thickness of 0.5-1.5 mm and a smooth surface.
8. The method for preparing a degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film for antibacterial fresh-keeping materials according to claim 2, characterized in that: The material of the filter membrane is polyethersulfone, polytetrafluoroethylene, nylon or polyvinylidene fluoride.
9. The method for preparing a degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film for antibacterial fresh-keeping materials according to claim 6, characterized in that: The polyurethane solution is an aqueous solution, and the relative molecular weight of the polyurethane is 10,000-50,000.
10. A degradable modified hydroxypropyl cellulose / polyurethane / Ag@NCQDs composite film for antibacterial and fresh-keeping materials prepared by the preparation method according to any one of claims 1 to 9.