Waterproof polymer film and preparation method thereof

Abstract

The invention relates to the technical field of polymer materials, in particular to a waterproof polymer film and a preparation method thereof. The waterproof polymer film specifically comprises the following components in parts by weight: 80-95 parts of polypropylene (PP) resin, 2-4 parts of an antibacterial agent, 3-6 parts of a compatilizer, 2-5 parts of a nano reinforcing agent and 0.1-0.5 part of an antioxidant. Through the synergistic effect of the compatilizer serving as a bridge, the nano SiO2 supported by a framework and the bonding type antibacterial agent which are added into a PP matrix, the waterproof polymer film has good mechanical property, waterproofness and lasting antibacterial property, and has a good application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high polymer materials, and particularly relates to a waterproof high polymer film and a preparation method thereof. BACKGROUND

[0002] Polypropylene films are widely used in packaging materials, medical health, agricultural covering and industrial protection due to their excellent thermal mechanical and gas barrier properties, chemical inertness, easy handling and good appearance. However, the traditional polypropylene film does not have antibacterial function, and is easy to breed microorganisms in the food packaging, medical dressing and other scenes with strict hygiene requirements, leading to product pollution, quality decline and even health risks. In addition, the polypropylene itself has a certain hydrophobicity, but its waterproof ability is limited, and the mechanical strength of the polypropylene still needs to be improved.

[0003] Therefore, there is an urgent need for a polypropylene high polymer film which can realize efficient and long-acting antibacterial, and has excellent mechanical strength and high water resistance. SUMMARY

[0004] The application aims to provide a waterproof high polymer film and a preparation method thereof, and solve the above technical problems in the prior art.

[0005] In order to achieve the above-mentioned purpose, the application adopts the following technical scheme: The application provides the following technical scheme: In a first aspect, the application provides a waterproof high polymer film, which specifically comprises the following components by weight: 80-95 parts of polypropylene (PP) resin, 2-4 parts of antibacterial agent, 3-6 parts of compatibilizer, 2-5 parts of nano reinforcing agent and 0.1-0.5 parts of antioxidant.

[0006] Preferably, the antioxidant is a mixture of antioxidant 1076 and antioxidant 168 in a mass ratio of 5:1.

[0007] Preferably, the PP is homopolymer polypropylene, and the melt index is 6-10 g / 10 min.

[0008] Preferably, the compatibilizer is maleic anhydride grafted polypropylene (PP-g-MAH).

[0009] Through the above technical scheme: the anhydride groups of PP-g-MAH can react with the amino groups at the ends of the antibacterial agent molecules, and the antibacterial agent molecules are bonded in the polymer matrix, so that the compatibility is improved, and the migration and loss of the antibacterial agent during use are prevented, and long-acting antibacterial is realized.

[0010] Preferably, the waterproof high polymer film has a thickness of 50-80 μm.

[0011] Preferably, the nano-enhancing agent is hydrophobically modified nanosilica.

[0012] Preferably, the method for preparing the hydrophobically modified nanosilica comprises the following steps: The nanosilica is added into ethanol, and after ultrasonic treatment, hexamethyldisilazane is added, and the ultrasonic treatment is continued, and then filtration, washing, and drying are performed to obtain the hydrophobically modified nanosilica.

[0013] Preferably, the ratio of the amounts of the nanosilica, ethanol, and hexamethyldisilazane is 15-20 g: 120-160 mL: 1-2 mL; the ultrasonic treatment conditions are that the ultrasonic treatment power is 300-500 W, and the ultrasonic treatment time is 25-35 min; the continued ultrasonic treatment time is 4-6 h; the washing method is that the filter residue is washed with ethanol for 3-5 times; and the drying method is drying at 55-65 ℃ until the weight is constant.

[0014] In the above process, the hexamethyldisilazane reacts with the silicon hydroxyl groups on the surface of the nanosilica to be grafted on the surface.

[0015] Preferably, the method for preparing the antibacterial agent comprises the following steps: S1: aniline, triethyl orthoformate, and methyl hydrazine carbonate are mixed, reflux stirring is performed in ethanol, then sodium methoxide is added, stirring is continued, cooling to room temperature is performed, impurities are removed, and an intermediate 1 is obtained; In the above process, the amino group of aniline undergoes Pinner reaction with triethyl orthoformate to generate imidate intermediate, and then reacts with aniline to generate benzamidine structure; in the hydrazine group, the primary amino group undergoes nucleophilic addition with the C=N double bond of benzamidine to generate open-chain adduct, and the adduct spontaneously performs intramolecular cyclization under the reaction conditions, and the amide nitrogen (-NH-) of the adduct performs intramolecular nucleophilic attack on the ester group (-COOCH3) of itself, and ring-closing demethanolization occurs to form a triazolone ring.

[0016] S2: the intermediate 1, 4-(2-bromoethoxy)benzaldehyde, potassium carbonate, potassium iodide, and acetone are mixed, reflux stirring is performed, impurities are removed, drying, filtration, and column chromatography purification are performed to obtain an intermediate 2; The structural formula of the intermediate 2 is as follows:

[0017] In the above process, SN2 reaction: N-1 of the triazolone ring of the intermediate 1 performs SN2 nucleophilic substitution reaction with the bromoalkyl carbon (-CH2-Br) in 4-(2-bromoethoxy)benzaldehyde.

[0018] S3: the intermediate 2, N-(4-methoxyphenyl)-hydrazine-carbothioamide, and ethanol are mixed, glacial acetic acid is added, reflux stirring is performed, and then standing and cooling to room temperature are performed, and then cooling in an ice water bath is performed, suction filtration is performed, and impurities are removed to obtain the antibacterial agent.

[0019] In the above process, the aldehyde group of intermediate 2 undergoes a condensation reaction with the free hydrazine nitrogen atom (-NH-) in N-(4-methoxyphenyl)-hydrazine carbide sulfonamide.

[0020] Preferably, in step S1, the ratio of aniline, triethyl orthoformate, methyl hydrazideformate, ethanol, and sodium methoxide is 9.3-19 g: 22.2-44.4 g: 13.5-27 g: 0.5-1 L: 8.1-16 g; reflux conditions: reflux temperature 78 °C, reflux time 20-28 h; continued stirring time 20-28 h; impurity removal method: solvent is removed by vacuum distillation, the resulting viscous residue is dissolved in 0.5-1 L of dichloromethane, washed successively with water and brine, and finally dried with MgSO4 to constant weight.

[0021] Preferably, in S2, the ratio of intermediate 1, 4-(2-bromoethoxy)benzaldehyde, potassium carbonate, potassium iodide, and acetone is 16.1-32g:21.5-43g:27.6-55g:1.7-3.4g:250-500mL; reflux stirring conditions: reflux stirring temperature is 57℃, and reflux stirring time is 5-7h; impurity removal method: acetone is removed by vacuum distillation, 0.5-1L of ethyl acetate and 0.3-0.6L of water are added to the residue, the liquid is separated, and the organic layer is washed successively with water and saturated brine; drying method: drying with Na2SO4 to constant weight; column chromatography uses a 5:1 volume ratio of petroleum ether and ethyl acetate as the eluent.

[0022] Preferably, in S3, the ratio of intermediate 2, N-(4-methoxyphenyl)-hydrazine-carbosulfan, ethanol, and glacial acetic acid is 3.1-6.2 g: 2.1-4.2 g: 150-300 mL: 3-6 drops; reflux stirring conditions: reflux stirring temperature is 78°C, reflux stirring time is 4-6 h; cooling time in an ice-water bath is 0.5-1.5 h; impurity removal method: the filter residue is washed with 20-40 mL of pre-cooled anhydrous ethanol, then purified by silica gel column chromatography, and concentrated under reduced pressure; silica gel column chromatography method: using a mixed solvent of chloroform and methanol as the eluent, the volume ratio is gradually increased from 100:1 to 20:1 for gradient elution, and the main fraction is collected.

[0023] Preferably, the preparation method of the N-(4-methoxyphenyl)-hydrazine-carbon sulfide includes the following steps: A hydrazine hydrate solution and dichloromethane were mixed and cooled in an ice bath. Under stirring conditions, a 4-methoxyphenyl isothiocyanate solution was slowly added dropwise. After the mixture was allowed to rise naturally to room temperature, stirring was continued, followed by filtration, washing, and vacuum drying to obtain N-(4-methoxyphenyl)-hydrazine-carbon thioamide.

[0024] The structural formula of N-(4-methoxyphenyl)-hydrazine-carbonthioamide is as follows:

[0025] In the above process, the hydrazine group (-NH-NH2) in hydrazine hydrate undergoes an addition reaction with the highly electrophilic carbon atom (-N=C=S) in 4-methoxyphenyl isothiocyanate to generate N-(4-methoxyphenyl)-hydrazine-carbonthioamide.

[0026] Preferably, the ratio of hydrazine hydrate solution to dichloromethane is 14-18 mL: 2-4 L; the mass fraction of hydrazine hydrate solution is 80 wt%; the cooling temperature is 0-5℃; the stirring speed is 300-500 rpm; the slow dripping time is 12-17 min; the stirring conditions are: the stirring temperature is 25-35℃ and the stirring time is 55-65 min; the washing method is: the solid is washed 2-3 times with cold dichloromethane; the vacuum drying method is: vacuum drying at 40-50℃ for 10-14 h.

[0027] Preferably, the 4-methoxyphenyl isothiocyanate solution is prepared by dissolving 33-66g of 4-methoxyphenyl isothiocyanate in a 0.5-1L solution of dichloromethane.

[0028] Secondly, the present invention also provides a method for preparing a waterproof polymer film, comprising the following steps: Step (1) Mix the antibacterial agent, compatibilizer, PP resin accounting for 20wt% of the total PP and antioxidant at room temperature for 3-5 minutes, then feed it into a twin-screw extruder, melt blend it at a temperature of 170-190℃ and a speed of 200-300rpm, extrude and granulate it to obtain a high-concentration antibacterial masterbatch. The above technical solution uses a small amount of resin as a carrier and the bridging effect of a compatibilizer (PP-g-MAH) in the molten state to pre-disperse the antibacterial agent molecules and promote the pre-reaction and chemical bonding of the amino groups at the ends of the antibacterial agent with the anhydride groups of the compatibilizer. This avoids the agglomeration or interface defects of the antibacterial agent in the film due to uneven dispersion, thus achieving long-lasting and stable antibacterial effect.

[0029] Step (2) The prepared antibacterial masterbatch, the remaining 80wt% of PP resin and nano-reinforcing agent are premixed in a high-speed mixer for 1-3 minutes according to the formula ratio. Then, they are added to a twin-screw extruder for melt blending. The extruded molten material is then transported to a casting casting machine and cast onto a cooling roller for cooling and shaping to obtain a waterproof polymer film.

[0030] Melt blending conditions: melt blending stirring temperature is 180-190℃, melt blending screw speed is 150-250rpm; cooling roller temperature is 20-40℃; casting machine traction speed is 150-250m / min.

[0031] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. In the microenvironment surrounding bacteria, the nitrogen atom on the triazolone ring of the antibacterial agent prepared in this invention undergoes protonation, forming a cationic center in the molecule. This center specifically adsorbs onto the negatively charged bacterial cell membrane through electrostatic interactions, disrupting membrane integrity. Simultaneously, the thiourea structure within the molecule can chelate metal ions essential for bacterial metabolism, inhibiting the activity of key enzymes. The aromatic ring system can insert between bacterial DNA base pairs, interfering with genetic material replication. The flexible linker enhances the binding compatibility between the molecule and the bacterial target, and the synergistic effect gives the antibacterial agent good antibacterial activity. Furthermore, while effectively combating bacteria, the antibacterial agent reduces the risk of bacteria developing single-target resistance.

[0032] 2. This invention utilizes the chemical reaction between the anhydride groups of PP-g-MAH and the amino groups at the end of the antibacterial agent to form chemical bonds, thereby fixing the antibacterial agent onto the polypropylene matrix, preventing the physical migration and loss of the antibacterial agent, and achieving the durability and stability of the antibacterial function.

[0033] 3. This invention enhances the compatibility with PP and improves the dispersion with silica through hydrophobically modified nano-SiO2; the good interfacial bonding enables the nanoparticles to effectively transfer external forces, restrict the excessive slippage of polymer chains, and improve the strength, stiffness and toughness of the film; and the uniformly distributed nanoparticles form a physical barrier in the film, extending the water molecule penetration path; at the same time, as a nucleating agent, it promotes finer PP crystallization, reduces water permeation channels, and improves waterproof performance.

[0034] 4. This invention achieves a waterproof polymer film with good mechanical properties, waterproofness, and long-lasting antibacterial properties by adding a compatibilizer as a bridge, nano-SiO2 as a skeleton support, and a bonded antibacterial agent to the PP matrix. It has good application prospects. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a TGA test chart of the antibacterial agent of the present invention; Figure 2 This is a diagram showing the mechanical properties of the waterproof polymer film of the present invention; Figure 3 This is a diagram illustrating the waterproof performance of the waterproof polymer film of the present invention. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] The substances and sources involved in the following examples and comparative examples are shown in Table 1: Table 1 Example

[0039] This embodiment discloses a method for preparing hydrophobically modified nano-silica, including the following steps: 18g of nano-silica was added to 140mL of ethanol and ultrasonically treated at 400W for 30min. Then, 1.5mL of hexamethyldisilazane was added and ultrasonic treatment was continued for 5h. The mixture was filtered, and the filter residue was washed with ethanol 4 times and dried at 60℃ to constant weight to obtain hydrophobic modified nano-silica. Example

[0040] This embodiment discloses a method for preparing N-(4-methoxyphenyl)-hydrazine-carbon thioamide, comprising the following steps: 16 mL of 80 wt% hydrazine hydrate solution and 3 L of dichloromethane were mixed and cooled to 3 °C in an ice-water bath. Under stirring at 400 rpm, 4-methoxyphenyl isothiocyanate solution was slowly added dropwise over 15 min. After naturally warming to room temperature, stirring was continued for 60 min in a 30 °C water bath. The mixture was then filtered, and the solid was washed three times with cold dichloromethane and dried under vacuum at 45 °C for 12 h to obtain N-(4-methoxyphenyl)-hydrazine-carbon thioamide.

[0041] The 4-methoxyphenyl isothiocyanate solution was prepared by dissolving 51g of 4-methoxyphenyl isothiocyanate in 0.75L of dichloromethane. Example

[0042] This embodiment discloses a method for preparing an antibacterial agent, including the following steps: S1: 14g aniline, 33.3g triethyl orthoformate and 20.5g methyl hydrazideformate were mixed and refluxed in 0.75L ethanol at 78°C for 24h. Then 12g sodium methoxide was added to the mixture and stirring was continued for 24h. The mixture was cooled to room temperature and the solvent was removed by vacuum distillation. The resulting viscous residue was dissolved in 0.75L dichloromethane, washed successively with water and brine, and dried with MgSO4 to obtain intermediate 1. S2: 24g of intermediate 1, 33g of 4-(2-bromoethoxy)benzaldehyde, 41g of potassium carbonate, 2.4g of potassium iodide and 380mL of acetone were mixed and refluxed at 57℃ for 6h. After the reaction was completed, the acetone was removed by vacuum distillation. 0.75L of ethyl acetate and 0.45L of water were added to the residue. The mixture was separated, and the organic layer was washed with water and saturated brine in turn. The residue was dried with Na2SO4 and filtered. The residue was purified by column chromatography to obtain intermediate 2. Column chromatography used a mixture of petroleum ether and ethyl acetate in a volume ratio of 5:1 as the eluent.

[0043] S3: Mix 4.6g of intermediate 2, 3.1g of N-(4-methoxyphenyl)-hydrazine-carbosulfan prepared in Example 2, and 230mL of anhydrous ethanol, then add 4 drops of glacial acetic acid, reflux and stir at 78°C for 5h, let stand and cool to room temperature, then cool in an ice-water bath for 1h, filter, wash the filter residue with 30mL of pre-cooled anhydrous ethanol, then purify by silica gel column chromatography, and concentrate under reduced pressure to obtain the antibacterial agent.

[0044] Silica gel column chromatography: using a mixture of chloroform and methanol as eluent, the volume ratio was gradually increased from 100:1 to 20:1, and the main fraction was collected; TGA chromatogram of antibacterial agents as shown below Figure 1 As shown. Example

[0045] This embodiment discloses a method for preparing a waterproof polymer film, including the following steps: Step (1) Mix 3g of antibacterial agent, 4.5g of PP-g-MAH, 17.2g of PP resin and 0.3g of antioxidant prepared in Example 3 at room temperature for 4 minutes, and then feed them into a twin-screw extruder. Melt blend at a temperature of 180℃ and a speed of 250rpm, extrude and granulate to obtain high-concentration antibacterial masterbatch. Step (2) The prepared antibacterial masterbatch, 68.8g of PP resin, and 3.5g of hydrophobic modified nano silica prepared in Example 1 are premixed in a high-speed mixer for 2 minutes. Then, they are added to a twin-screw extruder for melt blending. The extruded molten material is then transported to a casting casting machine and cast onto a cooling roller for cooling and shaping to obtain a waterproof polymer film.

[0046] Melt blending conditions: melt blending stirring temperature is 185℃, melt blending screw speed is 200rpm; cooling roller temperature is 30℃; casting machine traction speed is 200m / min.

[0047] The antioxidant is a mixture of antioxidant 1076 and antioxidant 168 in a mass ratio of 5:1. Example

[0048] This embodiment discloses a method for preparing a waterproof polymer film, including the following steps: Step (1) Mix 2g of antibacterial agent, 6g of PP-g-MAH, 16g of PP resin and 0.5g of antioxidant prepared in Example 3 at room temperature for 3 minutes, and then feed them into a twin-screw extruder. Melt blend at a temperature of 190℃ and a speed of 200rpm, extrude and granulate to obtain high-concentration antibacterial masterbatch. Step (2) The prepared antibacterial masterbatch, 64g of PP resin and 5g of hydrophobic modified nano silica prepared in Example 1 are premixed in a high-speed mixer for 1 minute, and then added to a twin-screw extruder for melt blending. The extruded molten material is then transported to a casting casting machine, cast onto a cooling roller, cooled and shaped to obtain a waterproof polymer film.

[0049] Melt blending conditions: melt blending stirring temperature is 190℃, melt blending screw speed is 150rpm; cooling roller temperature is 40℃; casting machine traction speed is 150m / min.

[0050] The antioxidant is a mixture of antioxidant 1076 and antioxidant 168 in a mass ratio of 5:1. Example

[0051] This embodiment discloses a method for preparing a waterproof polymer film, including the following steps: Step (1) Mix 4g of antibacterial agent, 3g of PP-g-MAH, 19g of PP resin and 0.1g of antioxidant prepared in Example 3 at room temperature for 5 minutes, and then feed them into a twin-screw extruder. Melt blend at a temperature of 170℃ and a speed of 300rpm, extrude and granulate to obtain high-concentration antibacterial masterbatch. Step (2) The prepared antibacterial masterbatch, 76g of PP resin, and 2g of hydrophobic modified nano silica prepared in Example 1 are premixed in a high-speed mixer for 3 minutes. Then, they are added to a twin-screw extruder for melt blending. The extruded molten material is then transported to a casting casting machine and cast onto a cooling roller for cooling and shaping to obtain a waterproof polymer film.

[0052] Melt blending conditions: melt blending stirring temperature is 180℃, melt blending screw speed is 250rpm; cooling roller temperature is 20℃; casting machine traction speed is 250m / min.

[0053] The antioxidant is a mixture of antioxidant 1076 and antioxidant 168 in a mass ratio of 5:1. Example

[0054] This embodiment discloses a method for preparing a waterproof polymer film, including the following steps: Step (1) Mix 2.2g of antibacterial agent, 5g of PP-g-MAH, 17g of PP resin and 0.4g of antioxidant prepared in Example 3 at room temperature for 3-5 minutes, and then feed them into a twin-screw extruder. Melt blend at a temperature of 185℃ and a speed of 220rpm, extrude and granulate to obtain high-concentration antibacterial masterbatch. Step (2) The prepared antibacterial masterbatch, 68g of PP resin and 4g of hydrophobic modified nano silica prepared in Example 1 are premixed in a high-speed mixer for 2 minutes, and then added to a twin-screw extruder for melt blending. The extruded molten material is then transported to a casting casting machine, cast onto a cooling roller, cooled and shaped to obtain a waterproof polymer film.

[0055] Melt blending conditions: melt blending stirring temperature is 185℃, melt blending screw speed is 180rpm; cooling roller temperature is 35℃; casting machine traction speed is 170m / min.

[0056] The antioxidant is a mixture of antioxidant 1076 and antioxidant 168 in a mass ratio of 5:1. Example

[0057] This embodiment discloses a method for preparing a waterproof polymer film, including the following steps: Step (1) Mix 3.5g of antibacterial agent, 4g of PP-g-MAH, 16.4g of PP resin and 0.2g of antioxidant prepared in Example 3 at room temperature for 4min, and then feed them into a twin-screw extruder. Melt blend at a temperature of 175℃ and a speed of 280rpm, extrude and granulate to obtain high-concentration antibacterial masterbatch. Step (2) The prepared antibacterial masterbatch, 65.6g PP resin, and 2.5g hydrophobic modified nano silica prepared in Example 1 are premixed in a high-speed mixer for 3 minutes, and then added to a twin-screw extruder for melt blending. The extruded molten material is then transported to a casting casting machine, cast onto a cooling roller, cooled and shaped to obtain a waterproof polymer film.

[0058] Melt blending conditions: melt blending stirring temperature is 185℃, melt blending screw speed is 220rpm; cooling roller temperature is 25℃; casting machine traction speed is 230m / min.

[0059] The antioxidant is a mixture of antioxidant 1076 and antioxidant 168 in a mass ratio of 5:1.

[0060] Comparative Example 1 Compared with Example 4, Comparative Example 1 did not add PP-g-MAH during the preparation of the waterproof polymer film, while other conditions remained unchanged.

[0061] Comparative Example 2 Compared with Example 4, Comparative Example 2 did not add hydrophobically modified nano-silica during the preparation of the waterproof polymer film, and all other conditions remained unchanged.

[0062] Comparative Example 3 Compared with Example 4, Comparative Example 3 used unmodified nano-silica instead of hydrophobic modified nano-silica in the process of preparing the waterproof polymer film, while keeping other conditions unchanged.

[0063] Comparative Example 4 Compared with Example 4, Comparative Example 4 did not add antibacterial agents during the preparation of the waterproof polymer film, and all other conditions remained unchanged.

[0064] Comparative Example 5 Compared with Example 4, Comparative Example 5 did not have step (1) in the process of preparing the waterproof polymer film. That is, all raw materials were added to the high-speed mixer at one time for premixing, and then directly melt-extruded and cast. All other conditions remained unchanged.

[0065] Antibacterial activity test: The test was conducted according to Appendix C of GB / T 21510-2008, using the film-coating method. After the sample was in contact with the bacterial solution for 18 hours, it was eluted in 20 mL of sterile water. After shaking well, the eluent was diluted 10 times, and 1 mL was inoculated into a petri dish. After incubation at 37°C for 24 hours, viable bacteria were cultured and counted. The total number of colonies (CFU) was determined according to GB / T4789.2-2008. The tested bacterial species were Escherichia coli ATCC25992 and Staphylococcus aureus ATCC25923. Calculation of test results: Antibacterial rate (%) = [(Blank control CFU - Sample CFU) / Blank control CFU] × 100%; According to the standard, when the antibacterial film reaches or exceeds 90% after 18 hours of contact with the bacterial solution, it can be said that the material has antibacterial effect; if the antibacterial rate reaches 99% or more, it indicates that the material has a strong antibacterial effect.

[0066] Mechanical property testing: The maximum load and elongation at break of the sample were tested in accordance with GB / T 13022.91 "Test Method for Tensile Properties of Plastic Films". The tensile speed was 50 mm / min and the test clamping distance was 50 mm.

[0067] Contact angle test: The sample to be tested was attached to a glass slide, and five different positions were taken for each sample. Deionized water was dropped onto the film surface for 5 seconds, and the image was saved. The degree was calculated and the average value was taken. The test results are shown in Table 2. Table 2

[0068] According to Table 2 and from Examples 4-8 and Comparative Examples 1-5, the waterproof polymer film prepared in Example 4 of this invention has good water resistance, antibacterial properties, and mechanical properties. A comparison between Comparative Example 1 and Examples 4-8 shows that without the addition of PP-g-MAH, the interfacial bonding between the hydrophobically modified nano-silica and the polypropylene matrix is ​​weak, the filler easily agglomerates to form stress concentration points, and the antibacterial agent is not chemically bonded, resulting in reduced antibacterial activity. Furthermore, early microcrack propagation occurs during stretching, leading to reduced mechanical properties and water resistance. A comparison between Comparative Example 2 and Examples 4-8 shows that without the addition of hydrophobically modified nano-silica, the lack of a micro-nano composite rough structure constructed from nanoparticles reduces the water contact angle and lacks the sustained-release and surface enrichment effects of the nanocarrier, resulting in a lower antibacterial rate. The system lacks nano-... The addition of an antimicrobial agent reduces mechanical properties. A comparison of Comparative Example 3 and Examples 4-8 shows that replacing hydrophobically modified nano-silica with unmodified nano-silica results in poor compatibility with the non-polar polypropylene matrix, leading to reduced mechanical properties. Simultaneously, the hydrophilic surface reduces water resistance, and the uneven dispersion of the antibacterial agent reduces the antibacterial rate. A comparison of Comparative Example 4 and Examples 4-8 shows that the absence of an antibacterial agent reduces antibacterial activity. A comparison of Comparative Example 5 and Examples 4-8 shows that directly blending all components without first preparing an antibacterial masterbatch results in uneven distribution of the antibacterial agent, reduced antibacterial rate, decreased material integrity, and reduced mechanical properties.

[0069] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0070] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A waterproof polymer film, characterized in that, The waterproof polymer film comprises the following components by weight: 80-95 parts PP resin, 2-4 parts antibacterial agent, 3-6 parts compatibilizer, 2-5 parts nano-reinforcing agent, and 0.1-0.5 parts antioxidant.

2. The waterproof polymer film according to claim 1, characterized in that, The antioxidant is a mixture of antioxidant 1076 and antioxidant 168 in a mass ratio of 5:1; the PP is homopolymer polypropylene with a melt index of 6-10 g / 10 min; the compatibilizer is maleic anhydride-grafted polypropylene (PP-g-MAH); the waterproof polymer film has a thickness of 50-80 μm; and the nano-reinforcing agent is hydrophobically modified nano-silica.

3. The waterproof polymer film according to claim 2, characterized in that, The method for preparing the hydrophobically modified nano-silica includes the following steps: Nano-silica was added to ethanol, ultrasonically treated, and then hexamethyldisilazane was added. The mixture was ultrasonically treated again, filtered, washed, and dried to obtain hydrophobically modified nano-silica. The ratio of nano-silica, ethanol, and hexamethyldisilazane is 15-20g:120-160mL:1-2mL; the ultrasonic treatment conditions are: ultrasonic power of 300-500W, ultrasonic treatment time of 25-35min, and continued ultrasonic treatment for 4-6h; the washing method is: the filter residue is washed with ethanol 3-5 times; the drying method is: dried at 55-65℃ to constant weight.

4. The waterproof polymer film according to claim 1, characterized in that, The method for preparing the antibacterial agent includes the following steps: S1: Aniline, triethyl orthoformate and methyl hydrazinoformate were mixed and refluxed in ethanol with stirring. Sodium methoxide was then added and stirring continued. The mixture was cooled to room temperature and impurities were removed to obtain intermediate 1. S2: Intermediate 1, 4-(2-bromoethoxy)benzaldehyde, potassium carbonate, potassium iodide and acetone were mixed, refluxed and stirred, impurities were removed, dried and filtered, and purified by column chromatography to obtain intermediate 2. S3: Mix intermediate 2, N-(4-methoxyphenyl)-hydrazine-carbonthioamide and ethanol, then add glacial acetic acid, reflux and stir, let stand and cool to room temperature, then cool in an ice water bath, filter, remove impurities, and obtain the antibacterial agent.

5. The waterproof polymer film according to claim 4, characterized in that, In S1, the ratio of aniline, triethyl orthoformate, methyl hydrazinoformate, ethanol, and sodium methoxide is 9.3-19 g: 22.2-44.4 g: 13.5-27 g: 0.5-1 L: 8.1-16 g; reflux conditions: reflux temperature 78℃, reflux time 20-28 h; continued stirring time 20-28 h; impurity removal method: solvent is removed by vacuum distillation, the resulting viscous residue is dissolved in 0.5-1 L of dichloromethane, washed successively with water and brine, and finally dried with MgSO4 to constant weight; in S2, the intermediate 1,4-(2-bromoethoxy)benzaldehyde The ratio of potassium carbonate, potassium iodide, and acetone used was 16.1-32g:21.5-43g:27.6-55g:1.7-3.4g:250-500mL; reflux stirring conditions: reflux temperature 57℃, reflux stirring time 5-7h; impurity removal method: acetone was removed by vacuum distillation, 0.5-1L ethyl acetate and 0.3-0.6L water were added to the residue, the layers were separated, and the organic layer was washed successively with water and saturated brine; drying method: dried with Na2SO4 to constant weight; column chromatography used a 5:1 volume ratio of petroleum ether and ethyl acetate as the eluent.

6. The waterproof polymer film according to claim 4, characterized in that, In S3, the ratio of intermediate 2, N-(4-methoxyphenyl)-hydrazine-carbosulfan, ethanol, and glacial acetic acid is 3.1-6.2 g: 2.1-4.2 g: 150-300 mL: 3-6 drops; reflux stirring conditions: reflux stirring temperature is 78℃, reflux stirring time is 4-6 h; cooling time in an ice-water bath is 0.5-1.5 h; impurity removal method: the filter residue is washed with 20-40 mL of pre-cooled anhydrous ethanol, then purified by silica gel column chromatography, and concentrated under reduced pressure; silica gel column chromatography method: using a mixed solvent of chloroform and methanol as eluent, the volume ratio is gradually increased from 100:1 to 20:1 for gradient elution, and the main fraction is collected.

7. The waterproof polymer film according to claim 4, characterized in that, The preparation method of the N-(4-methoxyphenyl)-hydrazine-carbon thioamide includes the following steps: A hydrazine hydrate solution and dichloromethane were mixed and cooled in an ice bath. Under stirring conditions, a 4-methoxyphenyl isothiocyanate solution was slowly added dropwise. After the mixture was allowed to rise naturally to room temperature, stirring was continued, followed by filtration, washing, and vacuum drying to obtain N-(4-methoxyphenyl)-hydrazine-carbon thioamide.

8. The waterproof polymer film according to claim 7, characterized in that, The ratio of hydrazine hydrate solution to dichloromethane is 14-18 mL: 2-4 L; the mass fraction of hydrazine hydrate solution is 80 wt%; the cooling temperature is 0-5℃; the stirring speed is 300-500 rpm; the slow dropwise addition time is 12-17 min; the stirring conditions are: stirring temperature is 25-35℃, and stirring time is 55-65 min; the washing method is: the solid is washed 2-3 times with cold dichloromethane; the vacuum drying method is: vacuum drying at 40-50℃ for 10-14 h; the 4-methoxyphenyl isothiocyanate solution is prepared by dissolving 33-66 g of 4-methoxyphenyl isothiocyanate in a solution of 0.5-1 L of dichloromethane.

9. A method for preparing a waterproof polymer film according to any one of claims 1-8, characterized in that, Includes the following steps: Step (1) Mix the antibacterial agent, compatibilizer, PP resin accounting for 20wt% of the total PP and antioxidant at room temperature, then feed them into a twin-screw extruder for melt blending, extrusion granulation, and obtain high-concentration antibacterial masterbatch. Step (2) The prepared antibacterial masterbatch, the remaining 80wt% of PP resin and nano-reinforcing agent are premixed in a high-speed mixer according to the formula ratio, and then added to a twin-screw extruder for melt blending. The extruded molten material is then transported to a casting casting machine, cast onto a cooling roller, cooled and shaped to obtain a waterproof polymer film.

10. The method for preparing the waterproof polymer film according to claim 9, characterized in that, In step (1), the mixing time is 3-5 min; the melt blending conditions are: melt blending temperature is 170-190℃, melt blending speed is 200-300 rpm; in step (2), the premixing time is 1-3 min; the melt blending conditions are: melt blending stirring temperature is 180-190℃, melt blending screw speed is 150-250 rpm; the cooling roller temperature is 20-40℃; the casting machine traction speed is 150-250 m / min.

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