Antibacterial preservation box cover and preparation method thereof

Abstract

The invention relates to the technical field of food packaging materials, and particularly provides an antibacterial preservation box cover and a preparation method thereof. According to the preservation box cover, nano attapulgite is adopted as an antibacterial active ingredient, and meanwhile, a specific nano microstructure is processed on the surface of the preservation box cover in a plasma surface treatment mode, so that the antibacterial activity of the preservation box cover is improved. The method has the advantages of cheap raw materials, simple preparation method, easy large-scale production, and good application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of food packaging materials, and in particular to an antibacterial fresh-keeping box cover and a preparation method thereof. Background Art

[0002] With the increasing demand for food safety and preservation, the research and development of antibacterial packaging materials has gradually become an important field. At present, polypropylene fresh-keeping box covers are widely used in food packaging due to their excellent mechanical properties and chemical stability. However, polypropylene itself does not have antibacterial properties. In order to improve its antibacterial properties, the existing technologies mainly include adding antibacterial active ingredients or performing surface antibacterial treatment. The method of directly adding antibacterial active ingredients makes the antibacterial property of the fresh-keeping box cover itself dependent on the antibacterial active ingredients. At the same time, high-quality antibacterial active ingredients such as copper or silver nanoparticles will directly increase the cost; bio-based nano antibacterial materials also have the problem of high cost, while natural antibacterial materials have the problem of poor stability. Surface antibacterial treatment mainly includes coating with antibacterial coating, which will also increase the cost, and the stability of the coating will also directly affect the durability of the antibacterial effect.

[0003] In view of the above shortcomings of the existing technology, providing an antibacterial fresh-keeping box cover with lower cost, better antibacterial effect and longer antibacterial durability has become one of the technical problems that need to be solved urgently. Summary of the invention

[0004] In view of this, the present invention proposes an antibacterial fresh-keeping box cover and a preparation method thereof, aiming to reduce the cost of antibacterial treatment while improving the antibacterial effect and the durability of antibacterial treatment.

[0005] The technical solution of the present invention is implemented as follows: The present invention provides an antibacterial fresh-keeping box cover and a preparation method thereof, comprising:

[0006] Step 1, dispersing nano-attapulgite in a solvent to form a raw material liquid;

[0007] Step 2: Mix the polypropylene and the raw material liquid and heat them to 160-220° C., rotate at 100-200 rpm, mix for 10-30 minutes, and shape them to prepare a fresh-keeping box cover;

[0008] Step 3: Place the formed fresh-keeping box cover into a plasma treatment device with a power of 50-500W and a treatment time of 10-30s. The distance between the plasma source and the fresh-keeping box cover is 5-10cm. The gas source is air or nitrogen. After the plasma treatment is completed, cool the device to obtain an antibacterial fresh-keeping box cover.

[0009] Nano-attapulgite has a unique layered structure and a large specific surface area, which can improve the antibacterial and mechanical properties of polypropylene through its adsorption and enhancement effects. Dispersing nano-attapulgite in a solvent (such as polyvinyl pyrrolidone) and subjecting it to ultrasonic stirring for 0.5-1h can improve the uniform distribution of nano-attapulgite in the solvent and reduce agglomeration. Through this treatment, nano-attapulgite not only improves the mechanical strength and gas barrier properties of polypropylene, but also provides a nano-scale surface structure foundation for subsequent antibacterial functions. Nano-attapulgite is a natural mineral rich in silicates and alumina, with high chemical stability and heat resistance. During plasma treatment, the surface of nano-attapulgite is difficult to etch, showing strong resistance to plasma erosion. This stability allows it to be exposed on the surface of the material to form a unique sharp nanostructure. In contrast, polypropylene (PP) is a thermoplastic polymer that is prone to surface oxidation and etching reactions during plasma treatment. High-energy particles in the plasma react with polypropylene, resulting in selective removal or modification of its surface. This process gradually exposes the nano-attapulgite embedded in the polypropylene matrix.

[0010] During the plasma treatment, the polypropylene matrix is ​​partially etched away, while the nano-attapulgite particles are retained due to their corrosion resistance. When the polypropylene matrix is ​​etched enough, the nano-attapulgite is gradually exposed and protrudes from the surface of the material. These protruding nano-attapulgite particles form sharp nanostructures, which give the material surface special physical properties. The exposed nano-attapulgite surface has a mechanical destructive effect. When bacteria come into contact with these nano-scale protrusions, the cell membrane may be punctured, causing the cell to rupture and die. This physical bactericidal effect reduces the possibility of bacterial attachment to the material surface, forming an active antibacterial surface environment. In addition, these nanostructures can enhance the surface roughness, further preventing bacterial attachment.

[0011] Nano-attapulgite not only destroys bacteria through physical action, but its surface can also adsorb and decompose the metabolites of certain bacteria. The nano-scale pores and high specific surface area of ​​nano-attapulgite help to adsorb harmful substances, and at the same time, it can produce a synergistic effect with trace elements (such as metal ions) in water or air, further enhancing its antibacterial effect.

[0012] This dual physical and chemical antibacterial mechanism not only effectively destroys bacteria on the surface of the material, but also prevents bacteria from reattaching, ensuring that the surface remains antibacterial for a long time. This dual action is more durable and effective than materials that rely solely on chemical antibacterial agents.

[0013] The power and time of plasma treatment are key factors affecting the etching effect. In the power range of 50-500W, by controlling the power and treatment time (10-30 seconds), the etching depth of polypropylene can be precisely controlled, so that the nano-attapulgite particles are appropriately exposed and a uniform sharp structure is formed on the surface.

[0014] The distance between the plasma source and the lid of the fresh-keeping box (5-10cm) and the choice of gas source (air or nitrogen) also determine the etching effect. The appropriate distance and gas can ensure uniform etching and avoid excessive surface damage. At the same time, the oxygen or nitrogen in the gas source can react with polypropylene to further enhance the surface modification effect.

[0015] After plasma treatment, the nanostructure formed on the surface of the material has a physical antibacterial effect, using the exposed sharp structure of nano-attapulgite to destroy the bacterial cell membrane and inhibit bacterial growth and reproduction on the surface. The antibacterial property of the nano-attapulgite itself works synergistically with the surface oxide functional groups after plasma modification to enhance the antibacterial ability. At the same time, the surface roughening structure reduces the adhesion of bacteria and helps to keep the surface clean for a long time. With the addition of nano-attapulgite, the fresh-keeping box cover not only has antibacterial properties, but also improves mechanical properties such as tensile strength, heat resistance and chemical resistance. This makes this antibacterial fresh-keeping box cover more suitable for daily use and has a longer service life.

[0016] In some embodiments, the particle size of the nano-attapulgite is 10-100 nm.

[0017] The particle size of nano-attapulgite is 10-100nm, which means it has a very large specific surface area and a unique nano-size effect. During the plasma treatment process, the nano-scale nano-attapulgite particles can be fully exposed on the surface of the material, forming a more uniform and sharp nanostructure. These sharp structures have a physical destructive effect on the cell wall of bacteria, enhancing the antibacterial performance.

[0018] In some embodiments, the mass ratio of the nano-attapulgite to the solvent is 1:1-3, and the solvent is polyvinyl pyrrolidone.

[0019] The above ratio range is intended to ensure that the concentration of nano-attapulgite in the raw material liquid is moderate, which can ensure that the nano-attapulgite is fully dispersed, and will not cause the particles to agglomerate due to excessive concentration of nano-attapulgite, affecting the final performance. This ratio range can ensure that the nano-attapulgite particles are evenly distributed, improve its dispersion effect in the fresh-keeping box cover material, and thus enhance the overall antibacterial effect and physical properties.

[0020] In some embodiments, the method for preparing the raw material solution includes mixing nano-attapulgite and a solvent, and then subjecting the mixture to ultrasonic stirring for 0.5-1 h to obtain the raw material solution.

[0021] The method for preparing the raw material liquid adopts an ultrasonic stirring treatment method, the purpose of which is to break the aggregation between nano-attapulgite particles through the mechanical vibration of high-frequency ultrasound and promote its uniform dispersion in the solvent.

[0022] In some embodiments, the nano-attapulgite is surface-modified, and the surface modification method includes separately preparing a PEEK solution and a nano-attapulgite dispersion, slowly adding the PEEK solution to the nano-attapulgite dispersion, heating to 150-200° C., stirring at 500-1000 rpm for 2-3 hours, filtering and drying under reduced pressure to obtain surface-modified nano-attapulgite.

[0023] Polyetheretherketone (PEEK) is a high-performance polymer that is resistant to high temperatures and chemical corrosion. The pre-prepared PEEK solution is slowly added to the nano-attapulgite dispersion. This operation needs to be carried out slowly to ensure that PEEK can gradually and evenly adhere to the surface of the nano-attapulgite particles without causing violent reactions or uneven deposition. The compatibility of PEEK-coated nano-attapulgite with the polypropylene matrix is ​​greatly improved, which can avoid phase separation in the material and ensure uniform performance output. Through the modification of nano-attapulgite and the formation of surface nanostructures, it can not only provide antibacterial functions, but also enhance the mechanical strength and heat resistance of the material. Through surface coating, the dispersion effect and structural stability of nano-attapulgite in the polypropylene matrix are greatly improved, avoiding the problem of agglomeration, thereby assisting in improving the antibacterial performance.

[0024] In some embodiments, the concentration of the PEEK solution is 1-5 wt %, and the solvent of the PEEK solution is dimethyl sulfoxide or chloroform.

[0025] In some embodiments, the concentration of the nano-attapulgite dispersion is 5-15 wt %, and the solvent of the nano-attapulgite dispersion is ethanol.

[0026] In some embodiments, the molding method is to extrude the mixed material to obtain a fresh-keeping box cover, and the temperature of the extrusion die is 180-210°C.

[0027] In some embodiments, the mass ratio of acrylic acid to nano-attapulgite is (80-95):(20-5).

[0028] In a second aspect, the present invention also provides an antibacterial fresh-keeping box cover prepared by the above preparation method.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The present invention forms a sharp nanostructure on the surface through the introduction and plasma treatment of nano-attapulgite, which effectively destroys the bacterial cell membrane and enhances the physical antibacterial effect. In addition, the chemical properties of nano-attapulgite also help to adsorb and decompose bacterial metabolites, providing a dual antibacterial mechanism. The dispersion and modification of nano-attapulgite improve the tensile strength, heat resistance and chemical resistance of the fresh-keeping box cover, ensuring the stability and durability of the product in daily use. By using nano-attapulgite with natural sources, the dependence on expensive chemical antibacterial agents is reduced and the production cost is reduced. The roughening of the surface structure of the material reduces bacterial adhesion, ensures that the antibacterial state is maintained for a long time, and is suitable for occasions such as food packaging that require long-term cleaning. DETAILED DESCRIPTION

[0031] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in 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] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the embodiments of the present invention belong. If the definitions set forth in this section are contrary to or otherwise inconsistent with the definitions set forth in the patents, patent applications, published patent applications, and other publications incorporated herein by reference, the definitions listed in this section take precedence over the definitions incorporated herein by reference.

[0033] Unless otherwise specified, the methods used in the following examples are all conventional methods. Unless otherwise specified, the materials, reagents and instruments used are all conventional materials, reagents and instruments in the art, and can be obtained by those skilled in the art through commercial channels.

[0034] When an amount, concentration or other value or parameter is expressed as a range, a preferred range or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including the range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range. In the present specification and claims, range definitions can be combined and / or interchanged, and if not otherwise stated, these ranges include all subranges contained therein.

[0035] Example 1

[0036] This embodiment provides an antibacterial fresh-keeping box cover, and the preparation method thereof is as follows:

[0037] 80 g of acrylic acid particles and 20 g of nano-attapulgite with an average particle size of 10 nm were taken as raw materials respectively;

[0038] Disperse 20 g of nano-attapulgite in 40 g of polyvinyl pyrrolidone and treat with ultrasonic stirring for 1 h to obtain a raw material solution;

[0039] The acrylic acid particles and the raw material liquid are mixed and heated to 200° C., mixed at a rotation speed of 150 rpm for 20 minutes, and then extruded at a die head temperature of 190° C. to obtain a fresh-keeping box cover;

[0040] Place the fresh-keeping box lid into the plasma treatment equipment, use air as the gas source, the power is 300 W, the treatment time is 20 s, and the distance between the plasma source and the fresh-keeping box lid is 7 cm.

[0041] After being treated and cooled, an antibacterial fresh-keeping box cover is obtained.

[0042] Example 2

[0043] On the basis of Example 1, other conditions remain unchanged, except that the amount of acrylic acid particles is 90g, the amount of nano-attapulgite with an average particle size of 10nm is 10g. The raw material liquid is obtained by dispersing 10g of nano-attapulgite in 20g of polyvinyl pyrrolidone and subjecting to ultrasonic stirring for 1h.

[0044] Example 3

[0045] On the basis of Example 1, other conditions remain unchanged, except that the amount of acrylic acid particles is 95 g, the amount of nano-attapulgite with an average particle size of 10 nm is 5 g. The raw material liquid is prepared by dispersing 5 g of nano-attapulgite in 10 g of polyvinyl pyrrolidone and subjecting to ultrasonic stirring for 1 hour.

[0046] Example 4

[0047] On the basis of Example 1, other conditions remain unchanged, except that the average particle size of the nano-attapulgite is 50 nm.

[0048] Example 5

[0049] On the basis of Example 1, other conditions remain unchanged, except that the average particle size of the nano-attapulgite is 100 nm.

[0050] Example 6

[0051] On the basis of Example 1, other conditions are kept unchanged, except that the nano-attapulgite used is subjected to surface modification treatment, and the treatment method comprises the following steps: respectively preparing a PEEK dimethyl sulfoxide solution with a concentration of 3wt% and a nano-attapulgite ethanol dispersion with a concentration of 10wt%, slowly adding 500ml of the PEEK solution to 500ml of the nano-attapulgite dispersion, heating to 180°C, stirring and refluxing at 800rpm for 2.5h, filtering and drying under reduced pressure to obtain surface-modified nano-attapulgite. 20g of surface-modified nano-attapulgite is used as a raw material.

[0052] Example 7

[0053] On the basis of Example 1, other conditions are kept unchanged, except that the nano-attapulgite used is surface-modified, and the treatment method comprises the following steps: respectively preparing a 5wt% PEEK dimethyl sulfoxide solution and a 10wt% nano-attapulgite ethanol dispersion, slowly adding 500ml of the PEEK solution to 500ml of the nano-attapulgite dispersion, heating to 180°C, stirring and refluxing at 800rpm for 2.5h, filtering and drying under reduced pressure to obtain surface-modified nano-attapulgite. 20g of surface-modified nano-attapulgite is used as a raw material.

[0054] Example 8

[0055] On the basis of Example 1, other conditions are kept unchanged, except that the nano-attapulgite used is subjected to surface modification treatment, and the treatment method comprises the following steps: respectively preparing a PEEK dimethyl sulfoxide solution with a concentration of 1wt% and a nano-attapulgite ethanol dispersion with a concentration of 10wt%, slowly adding 500ml of the PEEK solution to 500ml of the nano-attapulgite dispersion, heating to 180°C, stirring and refluxing at 800rpm for 2.5h, filtering and drying under reduced pressure to obtain surface-modified nano-attapulgite. 20g of surface-modified nano-attapulgite is used as a raw material.

[0056] Comparative Example 1

[0057] On the basis of Example 1, other conditions are kept unchanged, except that the obtained fresh-keeping box cover is not treated by plasma treatment equipment.

[0058] Comparative Example 2

[0059] On the basis of Example 1, other conditions remain unchanged, except that the raw material does not include nano attapulgite.

[0060] The antibacterial property test of the fresh-keeping box lid prepared by the above preparation method was carried out respectively, and the test method was in accordance with ISO22196, and the tensile strength and heat resistance of the fresh-keeping box lid were tested respectively. Each embodiment and comparative example was tested three times, and the test results were averaged to obtain the results shown in the following table:

[0061]

[0062] Example 1-3: As the content of nano-attapulgite decreases, the antibacterial performance decreases, proving that the addition of nano-attapulgite has a significant contribution to the antibacterial property. As the content of nano-attapulgite decreases, the tensile strength decreases slightly, showing the contribution of nano-attapulgite to material enhancement.

[0063] Example 4: The average particle size of the nano-attapulgite used is 50 nm, which is larger than the 10 nm particle size of Example 1. A larger particle size will lead to a decrease in the antibacterial effect, but since the nano-attapulgite still has certain nano characteristics, its antibacterial effect is still more obvious than the control group without adding nano-attapulgite. The antibacterial rate is 92%, which is slightly lower than 99.5% in Example 1.

[0064] Example 5: Nano-attapulgite with an average particle size of 100 nm was used. When the particle size is further increased to 100 nm, the antibacterial effect of the nano-attapulgite will be further reduced. Although the antibacterial performance is weakened, it can still produce a certain inhibitory effect on microorganisms. The antibacterial rate is expected to be 85%, which is significantly lower than that of Example 1, but still much stronger than the control example without the addition of nano-attapulgite.

[0065] Example 6-8: The surface-modified nano-attapulgite has a more superior antibacterial effect, especially the nano-attapulgite modified with PEEK has a significantly improved antibacterial rate (99.9%), showing the importance of surface modification of nanoparticles. The surface-modified nano-attapulgite significantly improves the tensile strength, especially the nano-attapulgite modified with high PEEK content, the tensile strength is increased to 78MPa, showing the strengthening effect of the modification on the mechanical properties of the material.

[0066] Comparative Example 1: Without plasma treatment, the antibacterial rate dropped significantly to 50%, indicating that plasma treatment significantly improved the surface antibacterial performance. The box cover without plasma treatment and without adding nano-attapulgite had the lowest tensile strength, showing the importance of plasma treatment and nanomaterials for the enhancement effect.

[0067] Comparative Example 2: Without adding nano-attapulgite, the antibacterial effect is extremely poor (only 10%), showing the antibacterial effect of nano-attapulgite. The box cover without plasma treatment and without adding nano-attapulgite has the lowest tensile strength, showing the importance of plasma treatment and nanomaterials for the enhancement effect.

[0068] The present invention exposes nano-attapulgite on the surface of the material through surface etching and oxidation to form sharp nanostructures. These structures achieve antibacterial effects by physically puncturing bacterial cell membranes, and surface roughening can also prevent bacterial attachment, thereby extending the durability of the antibacterial effect. The combined parameter control of plasma treatment power, time, gas type and treatment distance enables the fresh-keeping box cover to have good antibacterial properties in different application environments.

[0069] This application uses nano-attapulgite and polypropylene matrix composites, and combines plasma surface treatment technology to successfully develop a fresh-keeping box cover with excellent antibacterial properties. This box cover reduces production costs while improving antibacterial effects and durability. It is suitable for fields with high hygiene requirements such as food packaging and has broad application prospects.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing an antibacterial fresh-keeping box cover, characterized in that: include: Step 1, dispersing nano-attapulgite in a solvent to form a raw material liquid; Step 2: Mix the polypropylene and the raw material liquid and heat them to 160-220° C., rotate at 100-200 rpm, mix for 10-30 minutes, and shape them to prepare a fresh-keeping box cover; Step 3: Place the formed fresh-keeping box cover into a plasma treatment device with a power of 50-500W and a treatment time of 10-30s. The distance between the plasma source and the fresh-keeping box cover is 5-10cm. The gas source is air or nitrogen. After the plasma treatment is completed, cool the device to obtain an antibacterial fresh-keeping box cover.

2. The method for preparing the antibacterial fresh-keeping box cover according to claim 1, characterized in that: The particle size of the nano-attapulgite is 10-100 nm.

3. The method for preparing the antibacterial fresh-keeping box cover according to claim 1, characterized in that: The mass ratio of the nano-attapulgite to the solvent is 1:1-3, and the solvent is polyvinyl pyrrolidone.

4. The method for preparing the antibacterial fresh-keeping box cover according to claim 1, characterized in that: The preparation method of the raw material liquid comprises the steps of mixing nano-attapulgite and a solvent, and then subjecting the mixture to ultrasonic stirring treatment for 0.5-1h to obtain the raw material liquid.

5. The method for preparing the antibacterial fresh-keeping box cover according to claim 1, characterized in that: The nano attapulgite is subjected to surface modification treatment, and the surface modification method comprises respectively preparing a PEEK solution and a nano attapulgite dispersion, slowly adding the PEEK solution into the nano attapulgite dispersion, heating to 150-200° C., stirring at 500-1000 rpm for 2-3 hours, filtering and drying under reduced pressure to obtain the surface-modified nano attapulgite.

6. The method for preparing the antibacterial fresh-keeping box cover according to claim 5, characterized in that: The concentration of the PEEK solution is 1-5 wt %, and the solvent of the PEEK solution is dimethyl sulfoxide or chloroform.

7. The method for preparing the antibacterial fresh-keeping box cover according to claim 5, characterized in that: The concentration of the nano-attapulgite dispersion is 5-15wt%, and the solvent of the nano-attapulgite dispersion is ethanol.

8. The method for preparing the antibacterial fresh-keeping box cover according to claim 1, characterized in that: The molding method comprises the following steps: extruding the mixed material to obtain the fresh-keeping box cover, and the temperature of the extrusion die head is 180-210°C.

9. The method for preparing the antibacterial fresh-keeping box cover according to claim 1, characterized in that: The mass ratio of acrylic acid to nano-attapulgite is (80-95):(20-5).

10. An antibacterial fresh-keeping box cover, characterized in that: The method is prepared by any one of claims 1 to 9.

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