Composite antibacterial material loaded BOPP (biaxially-oriented polypropylene) pearlized film as well as preparation method and application thereof

Abstract

The invention discloses a novel BOPP (biaxially-oriented polypropylene) pearlized film loaded with a composite antibacterial material as well as a preparation method and application of the novel BOPP pearlized film, and the specific scheme is as follows: a KH550 coupling agent is hydrolyzed, a hydrolysate is modified on nano titanium dioxide (TiO2) particles, a natural antibacterial material eugenol (Eug) is brominated by a substitution reaction, and an Eug-TiO2 composite antibacterial material is further prepared based on nucleophilic substitution. And finally, carrying out melting plasticizing, extrusion casting and two-way stretching on polypropylene and pearlescent master batch to prepare the novel BOPP antibacterial pearlescent film, so that the strong activity, high stability, long action time, safety and environmental protection of the antibacterial process of the BOPP pearlescent film are realized, the added value attribute of the BOPP product is improved, and the application scene of the BOPP pearlescent film is expanded.

Description

Technical Field

[0001] The present invention belongs to the technical field of biaxially oriented polypropylene (BOPP) films, and particularly relates to a novel BOPP pearlescent film loaded with a Eu-TiO2 composite antibacterial material, and a preparation method and application thereof. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance some understanding of the overall background of the invention and should not be necessarily regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

[0003] BOPP film is a film product made by casting polypropylene melt into sheets, then biaxially stretching and slitting. It has the advantages of being non-toxic and odorless, having high mechanical strength and good dimensional stability, and has become one of the most widely used flexible packaging materials. As a high-value-added biaxially oriented polypropylene film, BOPP pearlescent film is widely used in food, pharmaceutical, cosmetics and other packaging applications due to its unique optical effects and functionality. However, BOPP pearlescent film has certain inherent air and water permeability, making it extremely susceptible to bacterial infection and microbial erosion when storing long-shelf-life products, affecting product quality. Therefore, the development of new BOPP antimicrobial pearlescent films has become increasingly important.

[0004] Inorganic antibacterial materials have the characteristics of broad-spectrum antibacterial, thermal stability and not easy to migrate out. Among them, the excellent anti-migration performance of TiO2 makes the migration amount during use far lower than that of nanosilver and other particles, and it has higher safety compared to metal antibacterial materials. However, the antibacterial effect of TiO2 depends on its own photocatalytic process, so it cannot provide effective antibacterial effect under weak light source and dark storage conditions. The natural antibacterial material Eug has the advantages of safety, environmental protection, and strong antibacterial activity, but its easy migration property leads to poor stability of its antibacterial effect and short duration of action, which greatly limits its application scenarios. Therefore, the development of antibacterial materials that meet the advantages of both inorganic and organic antibacterial materials can give full play to the complementary and synergistic effects of antibacterial effects, and is expected to simultaneously achieve the advantages of strong activity, high stability, long duration of action, safety and environmental protection of antibacterial materials, thereby matching BOPP pearlescent film with more diversified application conditions.

[0005] Adding synthetic organic antimicrobial materials to BOPP film can pose a threat to human health and the environment, while inorganic metal antimicrobial materials such as Ag and Cu are relatively expensive. Therefore, for safety, environmental protection, and cost considerations, current efforts to enhance the antimicrobial properties of BOPP pearlescent film by adding a single material primarily focus on inorganic metal oxides like TiO2 or natural organic antimicrobial materials. Developing functional BOPP films that can protect food from chemical and microbial contamination and resist external disturbances still requires resolving key scientific challenges.

[0006] Due to the limitations of photocatalytic antibacterial properties, TiO2 exhibits poor antibacterial activity in the dark. Natural antibacterial materials, when applied alone to BOPP film, suffer from poor stability and are easily lost through migration. Therefore, the key challenge lies in utilizing surface grafting reactions to design composite antibacterial materials that combine high antibacterial activity with long-term stability and can be applied to BOPP antibacterial pearlescent film to protect packaged products from microbial contamination. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention utilizes a natural antibacterial material, Eug, grafted onto the surface of nano-TiO2, which exhibits strong antibacterial stability and migration resistance. This method not only compensates for the lack of antibacterial efficacy of TiO2 under dim light sources or dark storage conditions, but also addresses issues such as Eug's easy migration, short antibacterial duration, and unstable efficacy. Furthermore, this antibacterial material is incorporated into the development of a new BOPP antibacterial pearlescent film, overcoming the deficiencies of existing BOPP pearlescent films in terms of antibacterial and antimicrobial properties. This further expands the application scenarios of BOPP pearlescent films and enhances their added value.

[0008] The technical solution adopted in the present invention is as follows: In a first aspect of the present invention, a method for preparing a BOPP pearlescent film loaded with a Eu-TiO2 composite antibacterial material is provided, the method comprising the following steps: (1) Dissolving KH550 silane coupling agent in a mixed solution of water and anhydrous ethanol, performing a hydrolysis reaction, and obtaining a KH550 reaction solution; adding nano-TiO2 to the mixed solution of water and anhydrous ethanol, performing ultrasonic dispersion, and obtaining a TiO2 dispersion; mixing the TiO2 dispersion with the KH550 reaction solution, performing a modification reaction, and washing and drying after the reaction to obtain KH550 modified TiO2; (2) Eugenol (Eug) is added to carbon tetrachloride (CCl4) and mixed evenly, and then N-bromosuccinimide and dibenzoyl peroxide are added to react; the precipitate is filtered, water is added to the filtrate for extraction, and brominated Eug is obtained after rotary evaporation; (3) KH550 modified TiO2 was added to CCl4 for ultrasonic dispersion, and then Eug bromide was added for closed reaction. After the reaction was completed, the mixture was washed and dried to obtain Eug-TiO2 composite antibacterial material; (4) The Eug-TiO2 composite antibacterial material, pearlescent masterbatch and polypropylene are premixed and added to a twin-screw extruder for melt plasticization and extrusion casting to prepare a casting sheet, and a pearlescent film is obtained based on biaxial stretching, which is BOPP pearlescent film.

[0009] In one or some embodiments of the present invention, in step (1), the ratio of the KH550 silane coupling agent to the mixed solution of water and anhydrous ethanol is (4.4-8.8) g: (150-200) mL, wherein the volume ratio of water to anhydrous ethanol is 1-2:3-6; and the hydrolysis reaction conditions are: 60-80 °C, 1-3 h, and pH 2-4.

[0010] In one or some embodiments of the present invention, in step (1), the average particle size of TiO2 is 60-200 nm; the modification reaction conditions are: 60-80°C, 2-5 h; the ratio of TiO2 to a mixed solution of water and anhydrous ethanol is (8-10) g: (150-200) mL, wherein the volume ratio of water to anhydrous ethanol is 1-2:3-6.

[0011] In one or some embodiments of the present invention, in step (2), the mass ratio of Eug, N-bromosuccinimide and dibenzoyl peroxide is (4-8): (6-8): (0.1-0.3); and the reaction conditions are: 50-70°C, 8-12h.

[0012] In one or some embodiments of the present invention, in step (3), the mass ratio of KH550-modified TiO2 and brominated Eug is (4-6) g: (6-10) g, and the closed reaction conditions are: 25-35 °C, 8-16 h.

[0013] In one or some embodiments of the present invention, in step (4), the content of the Eug-TiO2 composite antibacterial material is 3-6 wt%, and the content of the pearlescent masterbatch is 10-20 wt%, wherein the pearlescent masterbatch contains 35 wt% of polypropylene resin, 62 wt% of calcium carbonate, 2.1 wt% of alkyl sulfonate surfactant, 0.4 wt% of 1010 antioxidant, and 0.5 wt% of magnesium stearate lubricant.

[0014] Preferably, the polypropylene resin has a melt index of 0.8-10 g / min (230° C., 2.16 kg) and an isotacticity of 97%-99%.

[0015] In one or some embodiments of the present invention, in step (4), the temperatures of the feeding section, pressing section and plasticizing section of the extruder are 70°C, 200°C and 200°C respectively, and the temperature of the extrusion section is 200-230°C; the aspect ratio of the extruder screw is 28, the screw speed is 40-150 rpm, the die drawing ratio is 5-12, and the casting temperature is 30°C.

[0016] In one or some embodiments of the present invention, in step (4), the longitudinal stretching preheating temperature is 135~155℃, and the preheating time is 40 s; the longitudinal stretching temperature is 125~145℃, and the stretching ratio is 400%~700%; the transverse stretching preheating temperature is 145~165℃, and the preheating time is 30 s; the transverse stretching temperature is 135~160℃, and the stretching ratio is 500%~800%; and the stretching rate of the longitudinal and transverse stretching processes is 20~50% / s.

[0017] In a second aspect of the present invention, a BOPP pearlescent film loaded with Eug-TiO2 composite antibacterial material prepared by the above method is provided.

[0018] In a third aspect of the present invention, there is provided application of the BOPP pearlescent film in the field of packaging and / or decoration.

[0019] In the field of packaging, the BOPP pearlescent film is often used to prepare food packaging bags and / or daily chemical product packaging bags.

[0020] In the field of decoration, the BOPP pearlescent film is often used to prepare gift boxes, greeting cards, book covers and / or holiday decorations.

[0021] Compared with the related art known to the inventors, one of the technical solutions of the present invention has the following beneficial effects: By integrating natural antimicrobial materials with nano-TiO2 surface functionalization through the design of a suitable chemical grafting technique, a novel inorganic-organic composite antimicrobial material was produced. By leveraging the strong anti-migration properties of TiO2, the high antimicrobial activity of the natural antimicrobial material, and the synergistic antimicrobial effect of the composite material, a BOPP pearlescent film with beneficial antimicrobial properties was prepared. This improved the film's antimicrobial efficiency in dark environments and reduced the loss of antimicrobial material from the BOPP pearlescent film surface, significantly enhancing the film's antimicrobial durability and stability in adverse environmental conditions.

[0022] The Eu-TiO2 composite antimicrobial material prepared in this invention has a thermal decomposition temperature exceeding 350°C, thus possessing the thermal stability required for the BOPP production process. The BOPP pearlescent film containing the Eu-TiO2 composite antimicrobial material exhibited antimicrobial rates of 98.28% and 96.76% against E. coli and S. aureus, respectively, under light illumination. The antimicrobial efficacy remained stable in the dark, with the antimicrobial rates remaining above 95%. The antimicrobial material exhibited excellent migration resistance, and the BOPP pearlescent film maintained stable antimicrobial rates above 90% against E. coli and S. aureus, respectively, after 60 days of testing. These excellent antimicrobial properties significantly enhance the antimicrobial efficacy of the BOPP pearlescent film in the dark, reduce the loss of the antimicrobial material from the film surface, and significantly improve the film's antimicrobial duration and stability under adverse environmental conditions, ultimately achieving the strong antimicrobial activity, high stability, and long-lasting action characteristics of the BOPP antimicrobial pearlescent film. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings, which constitute a part of the specification of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0024] Figure 1 It shows the particle size distribution curve of TiO2 and Eug-TiO2 in Example 1.

[0025] Figure 2 Shows the thermogravimetric curves of TiO2 and Eug-TiO2 in Example 1.

[0026] Figure 3 The antibacterial stability curves of different BOPP antibacterial pearlescent films in Example 1 are shown. DETAILED DESCRIPTION

[0027] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0028] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations and / or combinations thereof.

[0029] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0030] The polypropylene grade used in all examples is T38F (isotacticity: 98.5%, melt index: 3 g / min (230°C, 2.16 kg)).

[0031] Example 1 A method for preparing a novel BOPP antibacterial pearlescent film loaded with a composite antibacterial material comprises the following steps: (1) Dissolve 4.4 g of KH550 silane coupling agent in a mixture of 200 mL of deionized water and anhydrous ethanol (1:4, v / v), adjust the pH to 3 with 5 wt.% dilute hydrochloric acid, and react at 70 °C for 2 h. Add 10 g of nano-TiO2 (60 nm) to a mixture of 200 mL of deionized water and anhydrous ethanol (1:4, v / v) and ultrasonically disperse for 40 min. Add the TiO2 dispersion to the KH550 reaction solution and continue to react at 70 °C for 2 h. After the reaction is completed, wash the solution with alcohol and centrifuge three times at a high-speed centrifugation speed of 10,000 rpm. Then, vacuum dry at 60 °C for 24 h to obtain KH550-modified TiO2.

[0032] (2) Add 6.56 g of Eug to 150 mL of CCl4 and mix well. Then add 7.12 g of N-bromosuccinimide and 0.24 g of dibenzoyl peroxide and react at 65 °C for 10 h. After filtering the precipitate, add 20 mL of deionized water to the filtrate for extraction. Then, evaporate under reduced pressure at 30 °C for 40 min to obtain Eug bromide.

[0033] (3) 4.5 g of KH550-modified TiO2 was added to 150 mL of CCl4 and ultrasonically dispersed for 60 min. 8 g of Euq bromide was added and the mixture was sealed and reacted at 30°C for 8 h. The mixture was washed with CCl4 repeatedly and centrifuged three times at a high speed of 12,000 rpm. The mixture was then dried in a vacuum at 65°C for 8 h to obtain the Euq-TiO2 composite antibacterial material.

[0034] (4) 4 wt% Eug-TiO2 composite antibacterial material, 16 wt% pearlescent masterbatch and 80 wt% polypropylene were premixed and added to a twin-screw extruder for melt plasticization and extrusion casting to prepare a casting sheet. The extrusion temperature was 200 °C, the screw speed was 120 rpm, and the die drawing ratio was 10. The casting sheet was biaxially stretched to obtain a pearlescent film. The longitudinal stretching preheating temperature was 145 °C and the preheating time was 40 s; the longitudinal stretching temperature was 130 °C, the stretching ratio was 600%, and the stretching rate was 30% / s; the transverse stretching preheating temperature was 155 °C and the preheating time was 30 s, the transverse stretching temperature was 145 °C, the stretching ratio was 700%, and the stretching rate was 30% / s.

[0035] The particle size distribution of the Eug-TiO2 composite antibacterial material prepared in step (1) of this embodiment is as follows: Figure 1 As shown in Figure 2, due to chemical grafting of Eug, the average particle size of Eug-TiO2 increases to 68.5 nm. The thermal gravimetric curve of Eug-TiO2 is shown in Figure 2. Figure 2 As shown in the figure, the initial degradation temperature of the Eug-TiO2 composite antibacterial material is 382 ℃. It will not undergo thermal degradation during the preparation of BOPP antibacterial pearlescent film and has the thermal stability required for BOPP processing.

[0036] The thickness of the BOPP pearlescent film prepared in step (4) of this example is 20.9 μm. In this example, pure Eu and unmodified TiO2 were used as antibacterial materials to prepare BOPP pearlescent films, which were compared as comparative examples. The comparative example has the same experimental steps as in Example 1, except that the type of antibacterial material was changed. The antibacterial activity test of BOPP films was conducted in accordance with the national standards GB / T 31402-2015 "Test Method for Antibacterial Properties of Plastic Surfaces" and GB 4789.2-2022 "National Food Safety Standard - Determination of Total Colony Count in Food Microbiological Examination". The antibacterial rates of different BOPP pearlescent films under dark conditions are shown in Table 1 (using LED lights to simulate sunlight). The antibacterial rates of BOPP pearlescent film containing TiO2 against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were 98.14% and 97.35% respectively under light irradiation, but dropped to 54.26% and 50.17% respectively under dark conditions. The antibacterial rates of BOPP pearlescent film containing Eug-TiO2 composite antibacterial material against E. coli and S. aureus were 98.28% and 96.76% respectively under light irradiation, while the antibacterial effect was stable under dark conditions, with antibacterial rates of 97.13% and 95.47% respectively. Figure 3As shown, the film was immersed in xylene and sealed, with samples taken every 20 days for testing of antibacterial efficacy. After 60 days of testing, the antibacterial efficacy of the BOPP pearlescent film containing the Eu-TiO2 composite antibacterial material remained stable, with antibacterial efficacy against E. coli and S. aureus remaining at 94.72% and 92.84%, respectively. The antibacterial efficacy of the Eu-TiO2-containing BOPP pearlescent film against E. coli and S. aureus decreased to 23.41% and 13.55%, respectively.

[0037] Table 1 Antibacterial rates of different BOPP antibacterial pearlescent films in Example 1 under light and dark conditions .

[0038] Example 2 A method for preparing a novel BOPP antibacterial pearlescent film loaded with a composite antibacterial material comprises the following steps: (1) 8.8 g of KH550 silane coupling agent was dissolved in 200 mL of a mixed solution of deionized water and anhydrous ethanol (1:4, v / v), the pH was adjusted to 3 with 5 wt.% dilute hydrochloric acid, and the mixture was reacted at 70 °C for 2 h. 10 g of nano-TiO2 (100 nm) was added to a mixed solution of 200 mL of deionized water and anhydrous ethanol (1:4, v / v) and ultrasonically dispersed for 40 min. The TiO2 dispersion was added to the KH550 reaction solution and the reaction was continued at 70 °C for 4 h. After the reaction was completed, the solution was washed with alcohol and centrifuged three times at a high speed of 10,000 rpm and dried in a vacuum at 60 °C for 24 h to obtain KH550-modified TiO2.

[0039] (2) Add 6.56 g of Eug to 150 mL of CCl4 and mix well. Then add 7.12 g of N-bromosuccinimide and 0.24 g of dibenzoyl peroxide and react at 65 °C for 10 h. After filtering the precipitate, add 20 mL of deionized water to the filtrate for extraction. Then, evaporate under reduced pressure at 30 °C for 40 min to obtain Eug bromide.

[0040] (3) 5.2 g of KH550-modified TiO2 was added to 150 mL of CCl4 and ultrasonically dispersed for 60 min. 8 g of Euq bromide was added and the mixture was sealed and reacted at 30°C for 12 h. The mixture was washed with CCl4 repeatedly and centrifuged three times at a high speed of 12,000 rpm. The mixture was then vacuum dried at 65°C for 8 h to obtain the Euq-TiO2 composite antibacterial material.

[0041] (4) 3 wt% Eug-TiO2 composite antibacterial material, 15 wt% pearlescent masterbatch and 82 wt% polypropylene were premixed and added to a twin-screw extruder for melt plasticization and extrusion casting to prepare a casting sheet. The extrusion temperature was 210 ℃, the screw speed was 120 rpm, and the die drawing ratio was 6. The casting sheet was biaxially stretched to obtain a pearlescent film. The longitudinal stretching preheating temperature was 155 ℃ and the preheating time was 40 s; the longitudinal stretching temperature was 145 ℃, the stretching ratio was 500%, and the stretching rate was 50% / s; the transverse stretching preheating temperature was 160 ℃ and the preheating time was 30 s, the transverse stretching temperature was 150 ℃, the stretching ratio was 700%, and the stretching rate was 30% / s.

[0042] The average particle size of the Eug-TiO2 composite antibacterial material prepared in step (1) of this embodiment increases to 110.2 nm, and the initial degradation temperature is 343 °C. It will not undergo thermal degradation during the preparation of the BOPP antibacterial pearlescent film and has the thermal stability required for BOPP processing.

[0043] The BOPP pearlescent film prepared in step (4) of this example had a thickness of 23.8 μm. Under light irradiation, the antibacterial rates against E. coli and S. aureus were 97.52% and 95.61%, respectively. Under dark conditions, the antibacterial effect against E. coli and S. aureus was stable, with antibacterial rates of 96.27% and 94.19%, respectively. After 60 days of xylene immersion, the BOPP pearlescent film maintained a stable antibacterial effect, with antibacterial rates against E. coli and S. aureus remaining at 94.28% and 92.39%, respectively.

[0044] Example 3 A method for preparing a novel BOPP antibacterial pearlescent film loaded with a composite antibacterial material comprises the following steps: (1) Dissolve 6.6 g of KH550 silane coupling agent in 200 mL of a mixed solution of deionized water and anhydrous ethanol (1:4, v / v), adjust the pH to 3 with 5 wt.% dilute hydrochloric acid, and react at 70 °C for 2 h. Add 10 g of nano-TiO2 (150 nm) to a mixed solution of 180 mL of deionized water and anhydrous ethanol (1:4, v / v) and ultrasonically disperse for 40 min. Add the TiO2 dispersion to the KH550 reaction solution and continue to react at 70 °C for 5 h. After the reaction is completed, the solution is washed with alcohol and centrifuged three times at a high-speed centrifugation speed of 10,000 rpm and dried in a vacuum at 60 °C for 24 h to obtain KH550-modified TiO2.

[0045] (2) Add 6.56 g of Eug to 150 mL of CCl4 and mix well. Then add 7.12 g of N-bromosuccinimide and 0.24 g of dibenzoyl peroxide and react at 65 °C for 10 h. After filtering the precipitate, add 20 mL of deionized water to the filtrate for extraction. Then, evaporate under reduced pressure at 30 °C for 40 min to obtain Eug bromide.

[0046] (3) 5.5 g of KH550-modified TiO2 was added to 150 mL of CCl4 and ultrasonically dispersed for 60 min. 8 g of Euq bromide was added and the mixture was sealed and reacted at 30 °C for 16 h. The mixture was washed with CCl4 repeatedly and centrifuged three times at a high speed of 14,000 rpm. The mixture was then vacuum dried at 65 °C for 8 h to obtain the Euq-TiO2 composite antibacterial material.

[0047] (4) 6 wt% Eug-TiO2 composite antibacterial material, 18 wt% pearlescent masterbatch and 76 wt% polypropylene were premixed and added to a twin-screw extruder for melt plasticization and extrusion casting to prepare a casting sheet. The extrusion temperature was 230 ℃, the screw speed was 90 rpm, and the die drawing ratio was 9. The casting sheet was biaxially stretched to obtain a pearlescent film. The longitudinal stretching preheating temperature was 150 ℃ and the preheating time was 40 s; the longitudinal stretching temperature was 135 ℃, the stretching ratio was 500%, and the stretching rate was 20% / s; the transverse stretching preheating temperature was 160 ℃ and the preheating time was 30 s, the transverse stretching temperature was 155 ℃, the stretching ratio was 500%, and the stretching rate was 30% / s.

[0048] The average particle size of the Eug-TiO2 composite antibacterial material prepared in step (1) of this embodiment increases to 158.5 nm, and the initial degradation temperature is 367 °C. It will not undergo thermal degradation during the preparation of the BOPP antibacterial pearlescent film and has the thermal stability required for BOPP processing.

[0049] The BOPP pearlescent film prepared in step (4) of this example had a thickness of 26.8 μm. Under light irradiation, the antibacterial rates against E. coli and S. aureus were 99.12% and 98.77%, respectively. Under dark conditions, the antibacterial effect against E. coli and S. aureus was stable, with antibacterial rates of 99.05% and 98.31%, respectively. After 60 days of xylene immersion, the BOPP pearlescent film maintained a stable antibacterial effect, with antibacterial rates against E. coli and S. aureus remaining at 96.74% and 95.93%, respectively.

[0050] Example 4 A method for preparing a novel BOPP antibacterial pearlescent film loaded with a composite antibacterial material comprises the following steps: (1) 6.6 g of KH550 silane coupling agent was dissolved in 200 mL of a mixed solution of deionized water and anhydrous ethanol (1:4, v / v), the pH was adjusted to 3 with 5 wt.% dilute hydrochloric acid, and the mixture was reacted at 70 °C for 2 h. 10 g of nano-TiO2 (60 nm) was added to a mixed solution of deionized water and anhydrous ethanol (1:4, v / v) and ultrasonically dispersed for 40 min. The TiO2 dispersion was added to the KH550 reaction solution and the reaction was continued at 70 °C for 5 h. After the reaction was completed, the solution was washed with alcohol and centrifuged three times at a high speed of 10,000 rpm and dried in a vacuum at 60 °C for 24 h to obtain KH550-modified TiO2.

[0051] (2) Add 6.56 g of Eug to 150 mL of CCl4 and mix well. Then add 7.12 g of N-bromosuccinimide and 0.24 g of dibenzoyl peroxide and react at 65 °C for 10 h. After filtering the precipitate, add 20 mL of deionized water to the filtrate for extraction. Then, evaporate under reduced pressure at 30 °C for 40 min to obtain Eug bromide.

[0052] (3) 4.5 g of KH550-modified TiO2 was added to 150 mL of CCl4 and ultrasonically dispersed for 60 min. 8 g of Euq bromide was added and the mixture was sealed and reacted at 30 °C for 10 h. The mixture was washed with CCl4 repeatedly and centrifuged three times at a high speed of 12,000 rpm. The mixture was then vacuum dried at 65 °C for 8 h to obtain the Euq-TiO2 composite antibacterial material.

[0053] (4) 4 wt% Eug-TiO2 composite antibacterial material, 20 wt% pearlescent masterbatch and 76 wt% polypropylene were premixed and added to a twin-screw extruder for melt plasticization and extrusion casting to prepare a casting sheet. The extrusion temperature was 200 °C, the screw speed was 60 rpm, and the die drawing ratio was 6. The casting sheet was biaxially stretched to obtain a pearlescent film. The longitudinal stretching preheating temperature was 150 °C and the preheating time was 40 s; the longitudinal stretching temperature was 145 °C, the stretching ratio was 700%, and the stretching rate was 40% / s; the transverse stretching preheating temperature was 160 °C and the preheating time was 30 s. The transverse stretching temperature was 160 °C, the stretching ratio was 700%, and the stretching rate was 50% / s.

[0054] The average particle size of the Eug-TiO2 composite antibacterial material prepared in step (1) of this embodiment increases to 69.4 nm, and the initial degradation temperature is 358 °C. It will not undergo thermal degradation during the preparation of the BOPP antibacterial pearlescent film and has the thermal stability required for BOPP processing.

[0055] The BOPP pearlescent film prepared in step (4) of this example had a thickness of 18.6 μm. Under light irradiation, the antibacterial rates against E. coli and S. aureus were 98.92% and 98.53%, respectively. Under dark conditions, the antibacterial effect against E. coli and S. aureus was stable, with antibacterial rates of 98.13% and 97.67%, respectively. After 60 days of xylene immersion, the BOPP pearlescent film maintained a stable antibacterial effect, with antibacterial rates against E. coli and S. aureus remaining at 97.08% and 96.35%, respectively.

[0056] Example 5 A method for preparing a novel BOPP antibacterial pearlescent film loaded with a composite antibacterial material comprises the following steps: (1) 8.8 g of KH550 silane coupling agent was dissolved in 200 mL of a mixed solution of deionized water and anhydrous ethanol (1:4, v / v), the pH was adjusted to 3 with 5 wt.% dilute hydrochloric acid, and the mixture was reacted at 70 °C for 2 h. 10 g of nano-TiO2 (200 nm) was added to a mixed solution of 200 mL of deionized water and anhydrous ethanol (1:4, v / v) and ultrasonically dispersed for 40 min. The TiO2 dispersion was added to the KH550 reaction solution and the reaction was continued at 70 °C for 3 h. After the reaction was completed, the solution was washed with alcohol and centrifuged three times at a high speed of 10,000 rpm and dried in a vacuum at 60 °C for 24 h to obtain KH550-modified TiO2.

[0057] (2) Add 6.56 g of Eug to 150 mL of CCl4 and mix well. Then add 7.12 g of N-bromosuccinimide and 0.24 g of dibenzoyl peroxide and react at 65 °C for 10 h. After filtering the precipitate, add 20 mL of deionized water to the filtrate for extraction. Then, evaporate under reduced pressure at 30 °C for 40 min to obtain Eug bromide.

[0058] (3) 5.0 g of KH550-modified TiO2 was added to 150 mL of CCl4 and ultrasonically dispersed for 60 min. 8 g of Euq bromide was added and the mixture was sealed and reacted at 30°C for 12 h. The mixture was washed with CCl4 repeatedly and centrifuged three times at a high speed of 12,000 rpm. The mixture was then dried in a vacuum at 65°C for 8 h to obtain the Euq-TiO2 composite antibacterial material.

[0059] (4) 6 wt% Eug-TiO2 composite antibacterial material, 12 wt% pearlescent masterbatch and 82 wt% polypropylene were premixed and added to a twin-screw extruder for melt plasticization and extrusion casting to prepare a casting sheet. The extrusion temperature was 220 °C, the screw speed was 100 rpm, and the die drawing ratio was 9. The casting sheet was biaxially stretched to obtain a pearlescent film. The longitudinal stretching preheating temperature was 145 °C and the preheating time was 40 s; the longitudinal stretching temperature was 140 °C, the stretching ratio was 600%, and the stretching rate was 20% / s; the transverse stretching preheating temperature was 150 °C and the preheating time was 30 s, the transverse stretching temperature was 145 °C, the stretching ratio was 600%, and the stretching rate was 20% / s.

[0060] The average particle size of the Eug-TiO2 composite antibacterial material prepared in step (1) of this embodiment increases to 209.7 nm, and the initial degradation temperature is 384.3 °C. It will not undergo thermal degradation during the preparation of the BOPP antibacterial pearlescent film and has the thermal stability required for BOPP processing.

[0061] The BOPP pearlescent film prepared in step (4) of this example had a thickness of 22.6 μm. Under light irradiation, the antibacterial rates against E. coli and S. aureus were 97.88% and 98.25%, respectively. Under dark conditions, the antibacterial effect against E. coli and S. aureus was stable, with antibacterial rates of 98.63% and 98.06%, respectively. After 60 days of xylene immersion, the antibacterial effect of the BOPP pearlescent film remained stable, with antibacterial rates against E. coli and S. aureus remaining at 96.11% and 95.76%, respectively.

[0062] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for preparing a BOPP pearlescent film loaded with a composite antibacterial material, characterized in that: The method comprises the following steps: (1) Dissolving KH550 silane coupling agent in a mixed solution of water and anhydrous ethanol, performing a hydrolysis reaction, and obtaining a KH550 reaction solution; adding nano-TiO2 to the mixed solution of water and anhydrous ethanol, performing ultrasonic dispersion, and obtaining a TiO2 dispersion; mixing the TiO2 dispersion with the KH550 reaction solution, performing a modification reaction, and washing and drying after the reaction to obtain KH550 modified TiO2; (2) Eugenol Eug is added to carbon tetrachloride CCl4 and mixed evenly, and then N-bromosuccinimide and dibenzoyl peroxide are added to react; the precipitate is filtered, water is added to the filtrate for extraction, and brominated Eugenol Eug is obtained after rotary evaporation; (3) KH550 modified TiO2 was added to CCl4 for ultrasonic dispersion, and then Eug bromide was added for closed reaction. After the reaction was completed, the mixture was washed and dried to obtain Eug-TiO2 composite antibacterial material; (4) The Eug-TiO2 composite antibacterial material, pearlescent masterbatch and polypropylene are premixed and added to a twin-screw extruder for melt plasticization and extrusion casting to prepare a casting sheet, and a pearlescent film is obtained based on biaxial stretching, which is BOPP pearlescent film.

2. The method for preparing the composite antibacterial material-loaded BOPP pearlescent film according to claim 1, wherein: In step (1), the ratio of the KH550 silane coupling agent to a mixed solution of water and anhydrous ethanol is (4.4-8.8) g: (150-200) mL, wherein the volume ratio of water to anhydrous ethanol is 1-2:3-6; the hydrolysis reaction conditions are: 60-80°C, 1-3h, and pH 2-4; The average particle size of TiO2 is 60-200 nm; the modification reaction conditions are: 60-80℃, 2-5h; The ratio of TiO2 to a mixed solution of water and anhydrous ethanol is (8~10) g: (150~200) mL, wherein the volume ratio of water to anhydrous ethanol is 1~2:3~6.

3. The method for preparing the composite antibacterial material-loaded BOPP pearlescent film according to claim 1, wherein: In step (2), the mass ratio of Eug, N-bromosuccinimide and dibenzoyl peroxide is (4-8): (6-8): (0.1-0.3); the reaction conditions are: 50-70°C, 8-12h.

4. The method for preparing the composite antibacterial material-loaded BOPP pearlescent film according to claim 1, wherein: In step (3), the mass ratio of KH550 modified TiO2 and brominated Eug is (4~6) g: (6~10) g, and the closed reaction conditions are: 25~35℃, 8~16 h.

5. The method for preparing the composite antibacterial material-loaded BOPP pearlescent film according to claim 1, wherein: In step (4), the content of the Eug-TiO2 composite antibacterial material is 3~6 wt%, and the content of the pearlescent masterbatch is 10~20 wt%, wherein the pearlescent masterbatch contains 35 wt% of polypropylene resin, 62 wt% of calcium carbonate, 2.1 wt% of alkyl sulfonate surfactant, 0.4 wt% of 1010 antioxidant, and 0.5 wt% of magnesium stearate lubricant.

6. The method for preparing the composite antibacterial material-loaded BOPP pearlescent film according to claim 1, wherein: In step (4), the temperatures of the feeding section, pressing section and plasticizing section of the extruder are 70°C, 200°C and 200°C respectively, and the temperature of the extrusion section is 200-230°C; the aspect ratio of the extruder screw is 28, the screw speed is 40-150 rpm, the die drawing ratio is 5-12, and the casting temperature is 30°C.

7. The method for preparing the composite antibacterial material-loaded BOPP pearlescent film according to claim 1, wherein: In step (4), the longitudinal stretching preheating temperature is 135~155℃, and the preheating time is 40 s; the longitudinal stretching temperature is 125~145℃, and the stretching ratio is 400%~700%; the transverse stretching preheating temperature is 145~165℃, and the preheating time is 30 s; the transverse stretching temperature is 135~160℃, and the stretching ratio is 500%~800%; the stretching rate of the longitudinal and transverse stretching processes is 20~50% / s.

8. A BOPP pearlescent film loaded with a composite antibacterial material prepared by the method according to any one of claims 1 to 7.

9. Use of the BOPP pearlescent film according to claim 8 in the field of packaging and / or decoration.

10. The use according to claim 9, characterized in that: In the field of packaging, the application of the BOPP pearlescent film in the preparation of food packaging bags and / or daily chemical product packaging bags; In the field of decoration, the BOPP pearlescent film is used in the preparation of gift boxes, greeting cards, book covers and / or holiday decorations.

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