A titanate nanomaterial composite polypropylene film and its preparation method

Abstract

This invention relates to a titanate nanomaterial composite polypropylene film and its preparation method, specifically providing a BOPP composite film masterbatch, which comprises modified titanate nanotubes, modified titanate nanowires, or modified titanate nanosheets, wherein the modified titanate nanotubes are titanate nanotubes adsorbed with surfactants, the modified titanate nanowires are titanate nanowires with surfactants adsorbed on their surfaces, and the modified titanate nanosheets are titanate nanosheets with surfactants coated on their surfaces.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterial modification and its application in plastics processing technology, specifically relating to a titanate nanomaterial composite polypropylene film and its preparation method. Background Technology

[0002] Biaxially oriented polypropylene (BOPP) film holds an important position in the packaging fields of food, pharmaceuticals, and tobacco due to its high transparency, excellent mechanical properties, and ease of processing. However, with the increasing demand for functional packaging in high-end packaging, the shortcomings of traditional BOPP film in areas such as scratch resistance, barrier properties, and heat-sealing performance are becoming increasingly apparent. For example, existing BOPP films have relatively low surface hardness, making them prone to scratches from mechanical friction during transportation or use, leading to deterioration of the packaging's appearance and even functional failure.

[0003] Traditional reinforcement techniques mainly improve material properties by adding inorganic fillers (such as carbon black and glass fiber), but these micron-sized fillers can significantly reduce the transparency and surface gloss of the film. For example, although carbon black can improve mechanical strength, its dark color leads to a significant decrease in light transmittance. Although nanomaterials have the advantage of high specific surface area, their high surface energy can easily cause agglomeration, resulting in stress concentration and performance anisotropy (China Packaging, 2024, 44(11): 37).

[0004] Therefore, further research is needed to develop BOPP films with a more balanced mechanical and optical properties.

[0005] Furthermore, with the rapid development of the modern packaging industry, the demand for high-performance packaging materials is increasing. Biaxially oriented polypropylene (BOPP) film, due to its excellent mechanical properties (such as high tensile strength, impact strength, and toughness), high transparency, non-toxicity, odorlessness, and good processing performance, has become the mainstream packaging material in the food, pharmaceutical, and tobacco industries (China Packaging, 2023, 43 (11): 27). However, with the upgrading of packaging function requirements in end-use scenarios, the limitations of traditional BOPP film in terms of barrier properties, heat resistance, and heat-sealing performance are gradually becoming apparent. For example, food packaging requires higher barrier properties to extend shelf life. In addition, excessively high heat-sealing temperatures may damage heat-sensitive contents and reduce production efficiency. Therefore, how to further improve the comprehensive performance of BOPP film while maintaining its original advantages has become a key direction for technological innovation in the industry.

[0006] For a long time, plastic reinforcement technology has mainly relied on adding inorganic or metal oxide fillers (such as carbon black, glass fiber, carbon fiber, etc.) to improve the mechanical properties of polymers. For example, carbon black can significantly improve the strength and modulus of materials through physical filling (Plastics Technology, 2025, 53 (01): 180). However, the introduction of these micron-sized fillers often leads to the deterioration of the optical properties of the materials. Due to its dark color, carbon black can significantly reduce the transparency of films, while the rigid structure of glass fiber can easily cause surface roughness and a decrease in gloss (Synthetic Resins and Plastics, 2017, 34 (01): 85). For BOPP films, high transparency and surface gloss are one of their core advantages. If optical properties are sacrificed due to the addition of fillers, it will seriously limit their application in the high-end packaging field. In addition, traditional fillers have poor dispersibility and are prone to agglomeration in the polymer matrix, resulting in stress concentration and anisotropy of mechanical properties (Zhejiang Chemical Industry, 2024, 55 (04): 20). Nanomaterials as fillers in plastic composites face two problems: First, the high surface energy of nanomaterials easily leads to their aggregation in the polymer matrix, forming micron-sized aggregates; second, most nanomaterials have polar groups on their surface, resulting in poor compatibility with common non-polar polymers.

[0007] Therefore, further research is needed on how to further improve the overall performance of BOPP film while maintaining its original advantages. Summary of the Invention

[0008] In view of the shortcomings of the prior art, the purpose of this invention is to provide a BOPP composite film with a more balanced mechanical and optical properties, which can not only improve the mechanical properties and heat sealing effect of the film, but also improve the scratch resistance of the BOPP film without affecting its gloss.

[0009] Previous studies have shown that light-colored nanomaterials, such as titanate nanotubes, can be prepared using a simple hydrothermal method (Nanoscale, 2013, 5(12): 5519). The inventors of this application have surprisingly discovered that modifying titanate nanotubes with surfactants can reduce their polarity and improve their dispersibility in the matrix. Furthermore, in the masterbatch prepared by mixing surfactant-modified titanate nanotubes with a carrier material, the titanate nanotubes are uniformly dispersed, exhibit excellent interfacial compatibility, and form a stable composite system with the carrier material. Further, the BOPP composite film prepared by mixing this masterbatch with the main material and additives not only significantly improves the tensile strength, heat-sealing strength, and barrier properties of the BOPP film, but also significantly enhances its scratch resistance. Simultaneously, the gloss and haze of the BOPP film remain unaffected, demonstrating excellent optical properties. This approach, which improves the mechanical properties of the film while maintaining excellent optical properties, provides a new technical direction for the development of high-end packaging materials and has broad application prospects.

[0010] The present invention also aims to provide a polypropylene film with a more balanced mechanical and optical properties, so as to simultaneously improve the longitudinal and transverse mechanical properties and transparency of BOPP film.

[0011] Existing technologies (Chemical New Materials, 2020, 48(2): 276) describe methods for preparing titanate nanowires. The inventors of this application have surprisingly discovered that modifying titanate nanowires with surfactants can improve their dispersibility in the matrix. Furthermore, in the masterbatch prepared by mixing surfactant-modified titanate nanowires with a carrier material, the titanate nanowires are uniformly dispersed. Further, the BOPP composite film prepared by mixing this masterbatch with the main material and additives is a transversely and longitudinally bidirectionally reinforced polypropylene film with improved transparency and a lower melting temperature, showing broad application prospects.

[0012] This invention also aims to overcome the shortcomings of existing BOPP films in achieving a balance between heat-sealing performance and strength, and provides a modified titanate nanosheet-reinforced BOPP film. This film enhances the crystallization rate of polypropylene through the nucleation effect of the nanosheets, improves the film's mechanical properties and heat-sealing effect, ensures the film's transparency and optical stability, and utilizes its UV absorption characteristics to improve degradation performance, making it suitable for the field of high-performance packaging materials.

[0013] Prior art (Nanoscale, 2013, 5, 5519) has been used to prepare titanate nanosheets. The inventors of this application have surprisingly discovered that modifying titanate nanosheets with surfactants can improve their dispersibility in a matrix. Furthermore, in a masterbatch prepared by mixing surfactant-modified titanate nanosheets with a carrier material, the titanate nanosheets are uniformly dispersed. Further, the BOPP composite film prepared by mixing this masterbatch with the main material and additives not only exhibits enhanced mechanical properties and a lower heat-sealing temperature, but also possesses excellent UV absorption and transmittance, thus achieving a balance between mechanical properties, heat-sealing performance, and UV degradation resistance, providing a new approach for the development of high-performance packaging materials.

[0014] Therefore, the present invention provides a BOPP composite membrane masterbatch comprising modified titanate nanotubes, modified titanate nanowires, or modified titanate nanosheets, wherein the modified titanate nanotubes are titanate nanotubes with surfactants adsorbed on their surfaces, the modified titanate nanowires are titanate nanowires with surfactants adsorbed on their surfaces, and the modified titanate nanosheets are titanate nanosheets with surfactants coated on their surfaces.

[0015] I. The masterbatch contains modified titanate nanotubes

[0016] In one aspect of the present invention, a BOPP composite film masterbatch is provided, which comprises modified titanate nanotubes, wherein the modified titanate nanotubes are titanate nanotubes with surfactants adsorbed on their surfaces.

[0017] In some embodiments, the titanate nanotubes are prepared by the following method: anatase-type nano-titanium dioxide is dispersed in a 10 mol / L NaOH aqueous solution (solid-liquid ratio 1.25:100), stirred until homogeneous, and then placed in a hydrothermal reactor and reacted at 120 °C for 48 hours. After cooling, the pH is adjusted to 1 with a 0.1 mol / L HCl solution. After treatment, the nanotubes are obtained by filtration, washing with water, and drying. In short, sodium titanate is synthesized directly by hydrothermal reaction of TiO2 in concentrated NaOH (10 mol / L); then, after acid washing and ion exchange, titanate is obtained. Therefore, those skilled in the art will understand that the "titanate" in this application refers to acidic titanate, i.e., hydrotitanate, with the chemical formula H2Ti3O7.

[0018] In some embodiments, the modified titanate nanotubes in the BOPP composite membrane masterbatch have a mass fraction of 5%-25% (e.g., 5%, 7%, 10%, 13%, 15%, 17%, 20%, 23% or 25%), preferably 10%-20%, and more preferably 15%.

[0019] In some embodiments, the modified titanate nanotubes are obtained by activating titanate nanotubes with a strong alkali and then mixing them with a surfactant.

[0020] In some embodiments, the modified titanate nanotubes are prepared by the following method:

[0021] (1) The titanate nanotubes are first mixed with a strong alkaline aqueous solution;

[0022] (2) The mixture obtained from the first mixing is then mixed with a surfactant in a second mixing process;

[0023] (3) The mixture obtained by the second mixing is filtered, washed with water and dried to obtain modified titanate nanotubes.

[0024] In some embodiments, the concentration of the strong base in the aqueous solution is 0.1-0.5 mol / L (e.g., 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L or 0.5 mol / L), preferably 0.3-0.5 mol / L, and more preferably 0.3 mol / L.

[0025] In some implementations, the second mixing is performed under ultrasonic conditions.

[0026] In some embodiments, the power of the ultrasound is 100W-1000W (e.g., 100 W, 200 W, 300 W, 400 W, 500 W, 600 W, 700 W, 800 W, 900 W or 1000 W), preferably 100W-500W, and more preferably 300W.

[0027] In some embodiments, the surfactant is selected from one or more long-chain alkyl quaternary ammonium salts containing 12 or more carbon atoms.

[0028] In some embodiments, the surfactant is selected from tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, octadecylammonium chloride, tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, octadecylammonium bromide, hexadecylpyridine chloride, or any combination thereof.

[0029] In some embodiments, the surfactant is tetradecyltrimethylammonium bromide.

[0030] In some embodiments, the strong base is selected from sodium hydroxide, potassium hydroxide, lithium hydroxide, or any combination thereof.

[0031] In some embodiments, the strong base is sodium hydroxide.

[0032] In some embodiments, in the first mixture, the mass ratio of the titanate nanotubes to the volume of the strong alkaline aqueous solution is 1 / 40 to 1 / 60 (g / mL), preferably 1 / 50 (g / mL).

[0033] In some embodiments, the surfactant is provided in the form of an aqueous solution in the second mixture.

[0034] In some embodiments, the surfactant is present in an aqueous solution at a mass percentage concentration of 3-8% (w / v), preferably 5% (w / v).

[0035] In some embodiments, the mass ratio of the titanate nanotubes to the volume of the aqueous solution of the surfactant is 1 / 40 to 1 / 60 (g / mL), preferably 1 / 50 (g / mL).

[0036] In some implementations, the first mixing time is 0.5-5 hours, preferably 1 hour.

[0037] In some embodiments, the ultrasound duration in the second mixing is 5 to 30 minutes, preferably 10 minutes.

[0038] In some embodiments, the BOPP composite membrane masterbatch also includes a carrier material.

[0039] In some implementations, the carrier material is polypropylene.

[0040] In some embodiments, the carrier material is maleic anhydride-grafted polypropylene.

[0041] In some embodiments, the masterbatch is obtained by mixing the modified titanate nanotubes with the carrier material in a mixer and then extruding and granulating the mixture using a mixer.

[0042] In another aspect of the present invention, the present invention provides a BOPP composite film, the raw material of which includes the masterbatch of any of the foregoing technical solutions.

[0043] In some embodiments, the mass fraction of the modified titanate nanotubes in the BOPP composite film is 0.05%-6.0% (e.g., 0.05%, 0.1%, 0.5%, 1.0%, 2.0%, 3.0%, 4.0%, 5.0% or 6.0%), preferably 0.5%-6.0%, more preferably 1.0%-4.0%, and most preferably 4.0%.

[0044] In some embodiments, the raw materials of the BOPP composite film also include a main material and additives.

[0045] In some implementations, the main material is polypropylene.

[0046] In some implementations, the main material is ternary copolymer polypropylene.

[0047] In some embodiments, the additives include slip agents, anti-adhesion agents, antioxidants, or any combination thereof.

[0048] In some embodiments, the mass fraction of the additives in the BOPP composite film is 1%-5%, preferably 2%.

[0049] In some embodiments, the BOPP composite film is prepared by the following method:

[0050] (1) The masterbatch, the main material and the additives are mixed and then extruded and granulated using a twin-screw extruder to obtain plastic pellets;

[0051] (2) The BOPP composite film is obtained by extrusion casting and planar biaxial stretching of the plastic rice.

[0052] In some embodiments, the conditions and processes of the planar biaxial stretching process are as follows: the quench roll temperature is controlled at 35 ℃; the longitudinal stretching preheating temperature is 110 ℃; the longitudinal stretching temperature is 105 ℃; the longitudinal stretching setting temperature is 80 ℃; the longitudinal stretching ratio is 5; the transverse stretching preheating temperature is 170 ℃; the transverse stretching temperature is 165 ℃; the transverse stretching setting temperature is 155 ℃; the transverse stretching ratio is 5.5; cooling; traction at a speed of 200 m / min; winding at a tension of 150 N / m.

[0053] II. Masterbatch contains modified titanate nanowires

[0054] In one aspect of the present invention, a BOPP composite film masterbatch is provided, which comprises modified titanate nanowires, wherein the modified titanate nanowires are titanate nanowires with surfactants adsorbed on their surfaces.

[0055] In some embodiments, the titanate nanowires are prepared by the following method: anatase-type nano-titanium dioxide is dispersed in a 10 mol / L NaOH aqueous solution (solid-liquid ratio 1.25:100), stirred until homogeneous, and then placed in a hydrothermal reactor and reacted at 200°C for 48 hours. After cooling, the pH is adjusted to 1 with a 0.1 mol / L HCl solution, filtered, washed with water, and dried at 100°C to obtain the titanate nanowires. In short, sodium titanate is synthesized directly by hydrothermal reaction of TiO2 in concentrated NaOH (10 mol / L); then, after acid washing and ion exchange, titanate is obtained. Therefore, those skilled in the art will understand that the "titanate" in this application refers to acidic titanate, i.e., hydrotitanate, with the chemical formula H₂Ti₃O₇.

[0056] In some embodiments, the modified titanate nanowires in the BOPP composite membrane masterbatch have a mass fraction of 2%-30% (e.g., 2%, 5%, 10%, 15%, 20%, 25% or 30%), preferably 2%-25%, more preferably 5-20%, and most preferably 10%.

[0057] In some embodiments, the modified titanate nanowires are obtained by activating titanate nanowires with a strong alkali and then mixing them with a surfactant.

[0058] In some embodiments, the modified titanate nanowires are prepared by the following method:

[0059] (1) The titanate nanowires are first mixed with a strong alkaline aqueous solution;

[0060] (2) The mixture obtained from the first mixing is then mixed with a surfactant in a second mixing process;

[0061] (3) The mixture obtained by the second mixing is filtered, washed with water and dried to obtain modified titanate nanowires.

[0062] In some embodiments, the concentration of the strong base in the aqueous solution is 0.05-1 mol / L (e.g., 0.05 mol / L, 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, 0.3 mol / L, 0.35 mol / L, 0.4 mol / L, 0.45 mol / L, 0.5 mol / L, or 1.0 mol / L), preferably 0.05-0.25 mol / L, more preferably 0.1-0.2 mol / L, and most preferably 0.1 mol / L.

[0063] In some implementations, the second mixing is performed under ultrasonic conditions.

[0064] In some embodiments, the power of the ultrasound is 50W-2000W (e.g., 50W, 100W, 300W, 500W, 700W, 1000W, 1300W, 1500W, 1700W or 2000W), preferably 50W-1500W, more preferably 100W-1000W, and most preferably 300W.

[0065] In some embodiments, the duration of the ultrasound is 5 to 60 minutes (e.g., 5 minutes, 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes or 60 minutes), preferably 5 to 40 minutes, more preferably 20 to 40 minutes, and most preferably 30 minutes.

[0066] In some embodiments, the surfactant is selected from one or more long-chain alkyl quaternary ammonium salts containing 12 or more carbon atoms.

[0067] In some embodiments, the surfactant is selected from tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, octadecyltrimethylammonium chloride, tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, octadecylammonium bromide, hexadecylpyridine chloride, dodecylpyridine chloride, or any combination thereof.

[0068] In some embodiments, the surfactant is hexadecyltrimethylammonium chloride.

[0069] In some embodiments, the strong base is selected from sodium hydroxide, potassium hydroxide, lithium hydroxide, or any combination thereof.

[0070] In some embodiments, the strong base is sodium hydroxide.

[0071] In some embodiments, in the first mixture, the mass ratio of the titanate nanowires to the volume of the strong alkaline aqueous solution is 1 / 40 to 1 / 60 (g / mL), preferably 1 / 50 (g / mL).

[0072] In some embodiments, the surfactant is provided in the form of an aqueous solution in the second mixture.

[0073] In some embodiments, the surfactant is present in an aqueous solution at a mass-volume concentration of 3-8% (w / v), preferably 5% (w / v).

[0074] In some embodiments, the mass ratio of the titanate nanowires to the volume of the aqueous solution of the surfactant is 1 / 80 to 1 / 120 (g / mL), preferably 1 / 100 (g / mL).

[0075] In some implementations, the first mixing time is 0.5-5 hours, preferably 1 hour.

[0076] In some embodiments, the BOPP composite membrane masterbatch also includes a carrier material.

[0077] In some implementations, the carrier material is polypropylene.

[0078] In some embodiments, the carrier material is maleic anhydride-grafted polypropylene.

[0079] In some embodiments, the masterbatch is obtained by mixing the modified titanate nanowires with the carrier material in a mixer and then extruding and granulating the mixture using a kneading mill.

[0080] In another aspect of the present invention, the present invention provides a BOPP composite film, the raw material of which comprises: the masterbatch described in any of the foregoing technical solutions.

[0081] In some embodiments, the mass fraction of the modified titanate nanowires in the BOPP composite film is 0.1%-8.0% (e.g., 0.1%, 0.5%, 1.0%, 2.0%, 3.0%, 4.0%, 5.0%, 6.0%, 7.0% or 8.0%), preferably 0.5%-6.0%, more preferably 1.0%-6.0%, and most preferably 4.0%.

[0082] In some embodiments, the raw materials of the BOPP composite film also include a main material and additives.

[0083] In some implementations, the main material is polypropylene.

[0084] In some implementations, the main material is ternary copolymer polypropylene.

[0085] In some embodiments, the additives include slip agents, anti-adhesion agents, antioxidants, or any combination thereof.

[0086] In some embodiments, the mass fraction of the additives in the BOPP composite film is 1%-5%, preferably 2%.

[0087] In some embodiments, the BOPP composite film is prepared by the following method:

[0088] (1) The masterbatch, the main material and the additives are mixed and then extruded and granulated using a twin-screw extruder to obtain plastic pellets;

[0089] (2) The BOPP composite film is obtained by extrusion casting and planar biaxial stretching of the plastic rice.

[0090] In some embodiments, the conditions and process of the planar biaxial stretching process are as follows: the temperature of the quench roll is controlled at 30 ℃; longitudinal stretching preheating, the temperature of the longitudinal stretching preheating roll is 80-150 ℃; longitudinal stretching, the temperature of the longitudinal stretching roll is 70-150 ℃; the temperature of the longitudinal stretching shaping roll is 20-80 ℃; the longitudinal stretching ratio is 5; the transverse stretching preheating temperature is 120-175 ℃; the temperature of the transverse stretching zone is 150-170 ℃; the temperature of the transverse stretching shaping zone is 100-150 ℃; cooling; traction, the speed is 200 m / min; winding, the tension is 150 N / m.

[0091] III. Masterbatch contains modified titanate nanotubes

[0092] In one aspect of the present invention, a BOPP composite film masterbatch is provided, which comprises modified titanate nanosheets, wherein the modified titanate nanosheets are titanate nanosheets with a surface coated with a surfactant.

[0093] In some embodiments, the titanate nanosheets are prepared by the following method: 2.5 g of anatase TiO2 is added to 200 mL of 10 mol / L NaOH aqueous solution, mixed thoroughly, and then added to a hydrothermal reactor. The reactor is placed at 90°C for 48 hours. After the reaction, the mixture is allowed to cool naturally to room temperature. The product is filtered and washed with 0.1 mol / L HCl and deionized water until the pH reaches approximately 1.0. After drying, titanate nanosheets are obtained. In short, sodium titanate is synthesized directly by hydrothermal reaction of TiO2 in concentrated NaOH (10 mol / L); then, after acid washing and ion exchange, titanate is obtained. Therefore, those skilled in the art will understand that the "titanate" in this application refers to acidic titanate, i.e., hydrotitanate, with the chemical formula H2Ti3O7.

[0094] In some embodiments, the modified titanate nanosheets in the BOPP composite membrane masterbatch have a mass fraction of 5%-25% (e.g., 5%, 10%, 15%, 20% or 25%), preferably 5%-20%, and more preferably 10%-20%.

[0095] In some embodiments, the modified titanate nanosheets are obtained by activating titanate nanosheets with a strong alkali and then mixing them with a surfactant.

[0096] In some embodiments, the modified titanate nanosheets are prepared by the following method:

[0097] (1) The titanate nanosheets are first mixed with a strong alkaline aqueous solution;

[0098] (2) The mixture obtained from the first mixing is then mixed with a surfactant in a second mixing process;

[0099] (3) The mixture obtained by the second mixing is filtered, washed with water and dried to obtain modified titanate nanosheets.

[0100] In some embodiments, the concentration of the strong base in the aqueous solution is 0.01-0.25 mol / L (e.g., 0.01 mol / L, 0.05 mol / L, 0.10 mol / L, 0.15 mol / L, 0.20 mol / L, or 0.25 mol / L), preferably 0.01-0.15 mol / L, more preferably 0.05-0.1 mol / L, and most preferably 0.1 mol / L.

[0101] In some embodiments, the first mixing time is 10 min to 2 h (e.g., 10 min, 30 min, 1 h or 2 h), preferably 30 min to 1 h, more preferably 30 min.

[0102] In some embodiments, the second mixing time is 10 min to 48 h (e.g., 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes, 2 hours, 3 hours, 4 hours, 5 hours, 10 hours, 15 hours, 20 hours, 25 hours, 30 hours, 35 hours, 40 hours, or 48 hours), preferably 20 min to 5 h, more preferably 30 min to 60 min, and most preferably 30 min.

[0103] In some embodiments, the surfactant is selected from one or more long-chain alkyl quaternary ammonium salts containing 12 or more carbon atoms.

[0104] In some embodiments, the surfactant is selected from tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, octadecyltrimethylammonium chloride, tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, octadecylammonium bromide, hexadecylpyridine chloride, dodecylpyridine chloride, or any combination thereof.

[0105] In some embodiments, the surfactant is hexadecyltrimethylammonium chloride.

[0106] In some embodiments, the strong base is selected from sodium hydroxide, potassium hydroxide, lithium hydroxide, or any combination thereof.

[0107] In some embodiments, the strong base is sodium hydroxide.

[0108] In some embodiments, in the first mixture, the mass ratio of the titanate nanosheets to the volume of the strong alkaline aqueous solution is 1 / 40 to 1 / 60 (g / mL), preferably 1 / 50 (g / mL).

[0109] In some embodiments, the surfactant is provided in the form of an aqueous solution in the second mixture.

[0110] In some embodiments, the surfactant is present in an aqueous solution at a mass-volume concentration of 3-8% (w / v), preferably 5% (w / v).

[0111] In some embodiments, the mass ratio of the titanate nanosheets to the volume of the aqueous solution of the surfactant is 1 / 40 to 1 / 60 (g / mL), preferably 1 / 50 (g / mL).

[0112] In some embodiments, the BOPP composite membrane masterbatch also includes a carrier material.

[0113] In some implementations, the carrier material is polypropylene.

[0114] In some embodiments, the carrier material is maleic anhydride-grafted polypropylene.

[0115] In some embodiments, the masterbatch is obtained by mixing the modified titanate nanosheets with the carrier material in a mixer and then extruding and granulating them using a kneading mill.

[0116] In another aspect of the present invention, the present invention provides a BOPP composite film, the raw material of which comprises: the masterbatch described in any of the foregoing technical solutions.

[0117] In some embodiments, the mass fraction of the modified titanate nanosheets in the BOPP composite film is 0.05%-8.0% (e.g., 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 1.0%, 2.0%, 3.0%, 4.0%, 5.0%, 6.0%, 7.0%, or 8.0%), preferably 0.2%-5.0%, and more preferably 1.0%-5.0%.

[0118] In some embodiments, the raw materials of the BOPP composite film also include a main material and additives.

[0119] In some implementations, the main material is polypropylene.

[0120] In some implementations, the main material is ternary copolymer polypropylene or heat-sealable polypropylene.

[0121] In some embodiments, the additives include slip agents, anti-adhesion agents, antioxidants, or any combination thereof.

[0122] In some embodiments, the mass fraction of the additives in the BOPP composite film is 1%-5%, preferably 2%.

[0123] In some embodiments, the BOPP composite film is prepared by the following method:

[0124] (1) The masterbatch, the main material and the additives are mixed and then extruded and granulated using a twin-screw extruder to obtain plastic pellets;

[0125] (2) The BOPP composite film is obtained by extrusion casting and planar biaxial stretching of the plastic rice.

[0126] In some embodiments, the conditions and process of the planar biaxial stretching process are as follows: the temperature of the quench roll is controlled at 30 ℃; longitudinal stretching preheating, the temperature of the longitudinal stretching preheating roll is 80-150 ℃; longitudinal stretching, the temperature of the longitudinal stretching roll is 70-150 ℃; the temperature of the longitudinal stretching shaping roll is 20-80 ℃; the longitudinal stretching ratio is 5; the transverse stretching preheating temperature is 120-175 ℃; the temperature of the transverse stretching zone is 150-170 ℃; the temperature of the transverse stretching shaping zone is 100-150 ℃; cooling; traction, the speed is 200 m / min; winding, the tension is 150 N / m.

[0127] Beneficial effects

[0128] 1.1 The BOPP film of the present invention has excellent mechanical properties, heat-sealing strength and scratch resistance, while not affecting its gloss.

[0129] 1.2 Modified titanate nanotubes are uniformly distributed in the BOPP matrix, which improves mechanical strength.

[0130] 1.3. Well-dispersed modified titanate nanotubes have heterogeneous nucleation capabilities, which can induce crystallization to form fine grains during the melting and cooling process of polypropylene, thereby optimizing the heat-sealing performance of BOPP film without affecting optical performance.

[0131] 1.4. By using a pre-dispersed masterbatch process, the problems of uneven dispersion and unstable processing that may be caused by the direct addition of modified titanate nanotubes can be reduced, thereby improving the rheological properties and processability during the film-making process.

[0132] 2.1 Modified titanate nanowires are better dispersed in BOPP. Modified titanate nanowires and maleic anhydride-grafted polypropylene are mixed to obtain masterbatch, which achieves the initial uniform dispersion of titanate nanowires. After mixing the masterbatch with ternary copolymer polypropylene, granulation is performed to further improve the good dispersibility of titanate nanowires and avoid their agglomeration.

[0133] 2.2 One-dimensional titanate nanowires have a large aspect ratio, so the biaxial stretching process in BOPP film manufacturing will also be oriented in both the length and width directions of the film plane, thereby achieving biaxial reinforcement of BOPP film.

[0134] 2.3. Well-dispersed titanate nanowires act as nucleating agents to induce polypropylene to crystallize more easily, which reduces the crystallization temperature and crystal size of polypropylene in the prepared titanate nanowire-reinforced polypropylene film, thereby improving transparency and reducing melting temperature.

[0135] 3.1 Titanate nanosheets have a high specific surface area and excellent thermal stability. They can easily form a dense barrier layer in the BOPP matrix, thereby effectively extending the diffusion path of gas and water molecules and significantly improving the barrier performance of the packaging film.

[0136] 3.2 Titanate nanosheets can act as nucleating agents, influencing the melting and crystallization process of BOPP films, thereby adjusting their heat-sealing properties. They also possess excellent UV absorption capabilities, thus promoting their degradation after disposal as packaging materials.

[0137] 3.3 Modified titanate nanosheets and maleic anhydride-grafted polypropylene are mixed to obtain a masterbatch, which achieves the initial uniform dispersion of modified titanate nanosheets. The masterbatch is then mixed with ternary copolymer polypropylene and granulated to further improve the good dispersibility of modified titanate nanosheets and avoid their agglomeration.

[0138] 3.4. Addressing the shortcomings of existing technologies, this invention proposes a strategy combining alkali treatment and surfactant modification to prepare hydrophobic titanate nanosheets. A highly dispersible masterbatch is then prepared using a compaction method, and finally, the nanofiller is oriented within the BOPP film through a biaxial stretching process. Simultaneously, the well-dispersed photoactive titanate nanosheets also contribute to the degradation performance of the BOPP packaging film after use. This technical approach not only solves the dispersion problem of nanofillers but also optimizes the crystallization behavior of polypropylene through nucleation effects, thereby achieving a balance between mechanical properties, heat-sealing performance, and UV degradation resistance, providing a new approach for the development of high-performance packaging materials. Attached Figure Description

[0139] Figure 1-1 Transmission electron microscope images of titanate nanotubes in Example 1-1.

[0140] Figure 1-2 Transmission electron microscope image of the modified titanate nanotubes after adsorption of surfactant in Example 1-1.

[0141] Figure 1-3 Photographs of masterbatches containing 10% modified titanate nanotubes prepared in Examples 1-3.

[0142] Figure 1-4 Transmission electron microscope images of BOPP composite films prepared from masterbatch with a modified titanate nanotube content of 15% in Examples 1-4.

[0143] Figure 1-5 Polarized light microscope images of BOPP films without additives and BOPP films with 2.0% modified titanate nanosheets added in Examples 1-5.

[0144] Figure 2-1 Transmission electron microscope images of the titanate nanowires before and after in Example 2-1.

[0145] Figure 2-2 Scanning electron microscope images of titanate nanowires in Example 2-1 after sonication for 5, 20, 40, and 60 minutes. Scale bar is 1 μm.

[0146] Figure 2-3 Photographs of the masterbatches prepared in Examples 2-4.

[0147] Figure 2-4 Examples 2-5 show photographs of BOPP films with a modified titanate nanowire content of 4.0%.

[0148] Figure 2-5 Scanning electron microscope images of BOPP films with directly added titanate nanowires and those with added titanate nanowires in Examples 2-5.

[0149] Figure 2-6 Transmission electron microscope images of the BOPP films in Examples 2-5.

[0150] Figure 2-7 Polarized light microscope images of BOPP films without additives and BOPP films with titanate nanowires added to the masterbatch in Examples 2-5.

[0151] Figure 2-8 DSC curves of BOPP membranes prepared in Examples 2-5.

[0152] Figure 3-1 Raman spectra of titanate nanosheets obtained under different alkali treatment times in Example 3-1.

[0153] Figure 3-2 Photograph of alkali-treated titanate nanosheets in Example 3-1.

[0154] Figure 3-3 The change in modifier concentration with treatment time in Example 3-2.

[0155] Figure 3-4 Transmission electron microscopy images of modified titanate nanosheets in Example 3-2.

[0156] Figure 3-5 Photographs of the membranes prepared in Examples 3-3.

[0157] Figure 3-6 Cooling DSC curves of BOPP films without additives in Examples 3-4, and BOPP films with 1.0%, 3.0%, and 5.0% modified titanate nanosheets.

[0158] Figure 3-7 Polarized light microscope images of BOPP films without additives in Examples 3-4, and BOPP films with 1.0%, 3.0%, and 5.0% of modified titanate nanosheets.

[0159] Figure 3-8 Transmission electron microscope images of the nanocomposite polypropylene films prepared in Examples 3-5.

[0160] Figure 3-9 UV spectra of BOPP films without additives and BOPP films with 3.0% and 5.0% modified titanate nanosheets added in Examples 3-6. Detailed Implementation

[0161] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings and examples. However, those skilled in the art will understand that the following drawings and examples are for illustrative purposes only and are not intended to limit the scope of the invention. Various objects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description of the drawings and preferred embodiments.

[0162] This invention provides a BOPP composite film and its preparation method. First, modified titanate nanotubes are prepared using alkali treatment and surfactant modification. Second, the modified titanate nanotubes are blended with maleic anhydride-grafted polypropylene to form a masterbatch. Finally, the masterbatch is mixed with ternary copolymer polypropylene, and a high-performance BOPP composite film is obtained through extrusion granulation, casting, and biaxial stretching processes. The formation of modified titanate nanotubes gives the BOPP composite film excellent mechanical strength, scratch resistance, and heat-sealing performance, while maintaining high light transmittance and surface gloss, making it suitable for high-end packaging applications.

[0163] This invention also provides a titanate nanowire-reinforced polypropylene film and its preparation method. First, modified titanate nanowires are mixed with maleic anhydride-grafted polypropylene to obtain a masterbatch. Second, the masterbatch is mixed with ternary copolymer polypropylene and extruded into granules. Finally, the granulated plastic pellets are subjected to extrusion blow molding and planar biaxial stretching processes to obtain a reinforced polypropylene film. This biaxially reinforced polypropylene film exhibits significantly improved gloss, transparency, and scratch resistance, while also reducing its heat-sealing temperature, thus showing significant application potential in the packaging field.

[0164] This invention also provides a nanocomposite polypropylene film and its preparation method, aiming to improve the mechanical properties, heat-sealing performance, transparency, and UV resistance of BOPP films. First, modified titanate nanosheets are acid-treated and modified with surfactants to achieve good dispersibility in polypropylene. Second, the modified titanate nanosheets are mixed with maleic anhydride-grafted polypropylene to obtain a masterbatch. Finally, the masterbatch is mixed with ternary copolymer polypropylene, extruded and granulated, and then subjected to extrusion blown film and planar biaxial stretching processes to obtain the nanocomposite polypropylene film. This technology has broad application prospects, especially in the fields of packaging materials, films, and heat-sealing films.

[0165] The technical solution of the present invention will be further described and illustrated below with reference to specific embodiments and accompanying drawings.

[0166] Example 1-1 (Preparation and Modification Conditions of Titanate Nanotubes)

[0167] Following the method described in the literature (Nanoscale, 2013, 5, 5519), anatase-type nano-titanium dioxide was dispersed in a 10 mol / L NaOH aqueous solution (solid-liquid ratio 1.25:100). After thorough stirring, the solution was placed in a hydrothermal reactor and reacted at 120 °C for 48 hours. After cooling, the pH was adjusted to 1 with 0.1 mol / L HCl solution. After treatment, the mixture was filtered, washed with water, and dried to obtain titanate nanotubes. The product was observed using a JEOL 2010 transmission electron microscope. Figure 1-1As shown, the product exhibits a distinct tubular structure with a high aspect ratio, and its diameter is mainly distributed in the range of 10-100 nm.

[0168] NaOH aqueous solutions with concentrations of 0.1 mol / L, 0.3 mol / L, and 0.5 mol / L were prepared respectively. The titanate nanotubes obtained above were accurately weighed and added to each solution, with a solid-liquid mass / volume ratio of 1:50 (g / mL), and stirred for 1 h. Then, a 5% tetradecyltrimethylammonium chloride aqueous solution was added, with the mass-to-volume ratio of titanate nanotubes being 1:50 (g / mL). After stirring until homogeneous, the solution was ultrasonically vibrated at 300 W for 10 minutes. The product was filtered, washed three times with water, and dried to obtain modified titanate nanotubes. These were weighed using a precision balance and labeled A, B, and C. An equal amount of titanate nanotubes was added directly to an equal volume of a 5% tetradecyltrimethylammonium chloride aqueous solution without NaOH treatment, with all other conditions remaining the same, and labeled D, serving as a control.

[0169] The calculated weight gain percentages of the above products are 5.0% (A), 7.2% (B), 7.4% (C), and 1.1% (D). Wherein, weight gain % = (M 后 -M 前 ) / M 前 x100%, where M 后 M represents the mass of the modified titanate nanotubes. 前 The value represents the mass of the titanate nanotubes before modification. This result indicates that treating the titanate nanotubes with NaOH aqueous solution facilitates surfactant adsorption. Furthermore, the inventors discovered that a concentration of 0.5 mol / L causes the titanate nanotubes to break down, transforming into other nano-TiO2 materials, such as nano-fragments. Therefore, a concentration of around 0.3 mol / L is more reasonable.

[0170] Samples from group B were observed using a transmission scanning electron microscope (JEOL 2010). Figure 1-2 As shown, the titanate nanotubes are coated with an amorphous material, indicating that the treatment method successfully adsorbs surfactants.

[0171] Further, under the above conditions, only the ultrasonic power of group B was changed to 100W, 500W, and 1000W. The resulting products were filtered, washed with water, dried, and weighed using a precision balance. The calculated weight gain rates of the products were 4.8%, 6.5%, and 4.4%, respectively, indicating that higher power is not conducive to the adsorption modification of surfactants.

[0172] Examples 1-2 (different surfactants and alkali solutions)

[0173] Titanate nanotubes were modified using a 0.3 mol / L NaOH aqueous solution and ultrasonic vibration at 300 W for 10 minutes, following the method described in Example 1-1. The surfactants used were: A: 5% hexadecyltrimethylammonium chloride; B: 5% octadecylammonium chloride; C: 5% tetradecyltrimethylammonium bromide; D: 5% hexadecyltrimethylammonium bromide; E: 5% octadecylammonium bromide; F: 5% hexadecylpyridine chloride. The modified products were filtered, washed, and dried. The zeta potential of the nanotubes in aqueous solution was measured using a Malvern Zetasizer Nano ZS instrument. The results are shown in Table 1-1. The surface of the titanate nanotubes modified with different surfactants all carried a positive charge, indicating that different modifiers could successfully modify titanate nanotubes.

[0174] The titanate nanotubes were modified according to the method in Example 1-1, using a 5% tetradecyltrimethylammonium bromide aqueous solution as the surfactant. The mixture was sonicated at 300W for 10 minutes, but the alkali treatment used a 0.3 mol / L KOH or LiOH aqueous solution. The resulting products were filtered, washed with water, dried, and weighed. The calculated weight gains were 6.5% and 7.7%, respectively, indicating that different alkali solutions could effectively adsorb surfactants onto the titanate nanotubes.

[0175] Based on the results of Examples 1-1, the mechanism of titanate nanotube modification may be: strong alkali causes the formation of a hydration layer or negative charge on the surface of titanate nanotubes, thereby promoting the adsorption of the hydrophilic end of the positively charged surfactant modifier on the surface, thus modifying the titanate nanotubes.

[0176] Table 1-1: Potentials of products modified with different surfactants

[0177] Examples 1-3 (Modified titanate nanotube masterbatch and its content)

[0178] Modified titanate nanotubes were prepared using the method described in Example 1-1, with 5% tetradecyltrimethylammonium bromide as a surfactant modifier, 0.3 mol / L NaOH aqueous solution, and ultrasonic vibration at 300 W for 10 minutes.

[0179] The modified titanate nanotubes were mixed with maleic anhydride-grafted polypropylene (brand name CMG9801, grafting rate 1.0%, Shanghai Rizhisheng New Technology Development Co., Ltd.), and then extruded and granulated through a mixer to obtain masterbatch. By adjusting the amount of maleic anhydride-grafted polypropylene added, masterbatches with modified titanate nanotube mass contents of 5%, 10%, 15%, 20%, and 25% were obtained respectively.

[0180] Figure 1-3The masterbatch prepared with 10% modified titanate nanotubes is a white, glossy granule. The prepared masterbatch was tested for melt flow rate (MFR), melting point, and crystallization temperature according to GB / T 3682-2018 and GB / T 19466.3-2004 standards. The results are shown in Table 1-2.

[0181] The results showed that the addition of modified titanate nanotubes to the masterbatch led to a decrease in melting point and crystallization temperature, indicating that it could improve the flowability and processing performance of the masterbatch. When the modified titanate nanotube content was 25% by mass, the masterbatch exhibited particles with fine cracks, indicating that the content of modified titanate nanotubes in the masterbatch was too high. Therefore, a modified titanate nanotube content in the masterbatch of no more than 20% by mass is more suitable.

[0182] Table 1-2: Test results of masterbatches containing different mass fractions of modified titanate nanotubes

[0183] Examples 1-4 (BOPP composite film)

[0184] The modified titanate nanotubes were set to have a mass content of 1.0% in the final film. The masterbatches with modified titanate nanotubes of 5%, 10%, 15%, and 20% mass content obtained in Examples 1-3 were mixed with ternary copolymer polypropylene (brand name FS5612, Singapore TPC Company) and then added with corresponding composite additives used in conventional BOPP film production, such as slip agent, anti-sticking agent (erucamide is used as an example in this example as slip agent and anti-sticking agent), and antioxidant (BASF composite antioxidant XT500 is used as an example in this example) (2% of the total mass in the final film). The mixture was extruded and granulated using a twin-screw extruder. The obtained plastic pellets were added to a biaxially oriented extrusion apparatus for BOPP heat-sealing film production for melting and extrusion casting. The conditions and process were as follows: quench roll temperature controlled at 35℃; longitudinal stretching preheating temperature at 110℃; longitudinal stretching temperature at 105℃; longitudinal stretching setting temperature at 80℃; longitudinal stretching ratio at 5; transverse stretching preheating temperature at 170℃; transverse stretching temperature at 165℃; transverse stretching setting temperature at 155℃; transverse stretching ratio at 5.5; cooling; traction at a speed of 200 m / min; winding at a tension of 150 N / m. In addition, films were also produced using the unmodified titanate nanotube masterbatch, unmodified titanate nanotube masterbatch, and modified titanate nanotubes directly added without masterbatch, through the same extrusion casting and planar biaxial stretching process described above.

[0185] The tensile strength, heat seal strength, haze, and gloss of the prepared BOPP film were tested using the national standard GB / T 12026-2000, and the moisture permeability of the prepared BOPP film was tested using the national standard GB / T 26253-2010. The results are shown in Tables 1-3 below.

[0186] The results showed that the mechanical properties of BOPP films prepared by adding unmodified titanate nanotube masterbatch and those prepared by directly adding modified titanate nanotubes without masterbatch were similar to those of BOPP films without masterbatch, but the gloss was lower and the haze was higher. In comparison, the tensile strength and heat-sealing strength of BOPP films prepared by adding modified titanate nanotubes in the form of masterbatch were improved, while the gloss and haze remained almost unchanged, and the moisture permeability was reduced. Furthermore, when the content of titanate nanotubes in the masterbatch was 10-20%, the tensile strength and heat-sealing strength were significantly improved, the gloss and haze remained almost unchanged, and the moisture permeability was significantly reduced.

[0187] The above results indicate that: (1) the masterbatch prepared by intensive mixing of modified titanate nanotubes and maleic anhydride-grafted polypropylene achieves preliminary uniform dispersion of titanate nanotubes; granulation after mixing the masterbatch with ternary copolymer polypropylene further improves the good dispersibility of titanate nanotubes and avoids their agglomeration; (2) titanate nanotubes do not affect the transparency and gloss of the packaging film; (3) well-dispersed titanate nanotubes easily form a dense barrier layer in the BOPP matrix, effectively extending the diffusion path of gas molecules and significantly improving the barrier performance of the packaging film. Further, a BOPP composite film prepared from a masterbatch containing 15% modified titanate nanotubes was observed using transmission electron microscopy, as shown... Figure 1-4 As shown, modified titanate nanotubes are uniformly dispersed in BOPP films and arranged to a certain extent along a specific direction, which can effectively disperse external forces and improve the mechanical properties of BOPP composite films. Therefore, the preferred content of titanate nanotubes in the masterbatch is 10-20%.

[0188] Table 1-3: Test results of different BOPP films

[0189] Examples 1-5 (Content of modified titanate nanotubes in BOPP)

[0190] The masterbatch with a modified titanate nanotube content of 15% prepared in Examples 1-3 was used to prepare BOPP films with a total modified titanate nanotube content of 0.05%, 0.1%, 0.5%, 1.0%, 2.0%, 4.0%, and 6.0% respectively using the BOPP film preparation process in Examples 1-4. The films were then tested, and the results are shown in Tables 1-4 below.

[0191] The results showed that: (1) the mechanical properties of BOPP film first increased and then decreased with the increase of modified titanate nanotube content; (2) when the amount of modified titanate nanotube added exceeded 0.5%, the moisture permeability of BOPP film decreased significantly and the heat sealing strength increased significantly; (3) when the amount of modified titanate nanotube added reached 6.0%, the mechanical properties of BOPP film decreased, while the gloss decreased and the haze increased. Taking all factors into consideration, the preferred amount of modified titanate nanotube added to BOPP film is 0.5%-6.0%; more preferably 1.0%-4.0%.

[0192] Table 1-4: Test results of BOPP films containing different contents of modified titanate nanotubes

[0193] The above samples were subjected to programmed temperature rise / fall tests under a nitrogen atmosphere using a differential scanning calorimeter (Netzsch DSC 204 F1). The heat flow curves of each group of samples were recorded, and Tc, Tm, and heat of crystallization (ΔHc) were extracted to calculate the crystallinity. The results are shown in Table 1-5.

[0194] The results showed that with the increase of modified titanate nanotube content, the crystallization temperature of BOPP film gradually decreased, while the melting temperature remained relatively stable. The overall increase in the heat of crystallization indicates that the modified nanotubes played a good nucleation role in the system, accelerating the arrangement and crystallization of polymer chains to improve the crystallization rate and crystallinity. During the heat sealing process, this manifests as adjacent polypropylene molecular chains fusing more fully in the molten state and forming a uniform and stable crystal structure after cooling, thereby enhancing the sealing strength.

[0195] Table 1-5: Tc, Tm and heat of crystallization (ΔHc) of BOPP films containing different contents of modified titanate nanotubes

[0196] The BOPP film without additives (see Examples 1-4) and the BOPP film with 2.0% modified titanate nanotubes were observed using a Japanese Olympus BX53 polarizing microscope. The results are as follows: Figure 1-5 As shown: Under a polarizing microscope, the BOPP film without added spherulite nanotubes exhibits a large spherulite structure with uneven grain size and crystal defects in some areas. The BOPP film with 2.0% modified titanate nanotubes shows a significantly reduced spherulite size and a more uniform grain distribution. The polarizing microscope observations further confirm that the modified titanate nanotubes play an effective nucleation role in the BOPP film, promoting rapid polypropylene crystallization and optimizing the grain structure. The finer, more uniform spherulite structure not only helps improve the mechanical properties of the film but also enhances its transparency and reduces haze.

[0197] Examples 1-6 (Scratch resistance of BOPP composite film)

[0198] BOPP films with modified titanate nanotubes comprising 0.05%-6.0% of the final film material were prepared using the methods described in Examples 1-5. The surface of the BOPP films was examined using the MTS Nano Indenter XP test to calculate their hardness and elastic modulus, and their abrasion resistance was further tested according to GB / T 3960-2016. The results are shown in Tables 1-6 below.

[0199] The results showed that with the increase of modified titanate nanotube content in BOPP, the hardness and modulus of the BOPP film gradually increased, while the mass wear decreased accordingly. This indicates that when added in appropriate amounts, modified titanate nanotubes can enhance the surface strength of the BOPP film, improve its scratch resistance, and make it more wear-resistant and less prone to deformation during friction. When the modified titanate nanotube content was 4.0%, both the hardness and elastic modulus reached their peak values, and the scratch resistance of the BOPP film was optimal. Therefore, the preferred mass fraction of modified titanate nanotubes in BOPP composite films is 1.0%-4.0%.

[0200] Table 1-6: Test results of BOPP films containing different contents of modified titanate nanotubes

[0201] Example 2-1 (Activation and Modification Conditions for Titanate Nanowires)

[0202] First, titanate nanowires were prepared according to the method described in the literature (New Chemical Materials, 2020, 48(2): 276): Anatase nano-titanium dioxide was dispersed in a 10 mol / L NaOH aqueous solution (solid-liquid ratio of 1.25:100), stirred evenly, and then placed in a hydrothermal reactor and reacted at 200℃ for 48 hours. After cooling, the pH value was adjusted to 1 with 0.1 mol / L HCl solution, filtered and washed with water, and then dried at 100℃ to obtain titanate nanowires.

[0203] A 5% (w / v) hexadecyltrimethylammonium chloride aqueous solution was prepared. The obtained titanate nanowires were accurately weighed and directly added to the hexadecyltrimethylammonium chloride aqueous solution at a solid-liquid mass / volume ratio of 1:100 (g / mL). After stirring evenly, the solution was ultrasonically vibrated at 300W for 30 minutes. The product was filtered, washed three times with water, dried, and weighed using a precision balance. Another equal amount of titanate nanowires was added to a 0.1 mol / L NaOH aqueous solution (solid-liquid mass / volume ratio of 1:50 g / mL) and stirred for 1 hour. The same volume of hexadecyltrimethylammonium chloride aqueous solution was then added, stirred evenly, and ultrasonically vibrated at 300W for 30 minutes. The product was filtered, washed three times with water, dried, and weighed using a precision balance. The results showed that the titanate nanowires without NaOH activation treatment increased in weight by 1.2%, while those with NaOH activation treatment increased in weight by 7.3%. The weight gain % = (M... 后 -M 前 ) / M 前 x100%, where M 后 M represents the mass of the modified titanate nanowires. 前 This indicates the mass of the titanate nanowires before modification.

[0204] This result indicates that NaOH activation treatment facilitates the successful modification of titanate nanowires. The structures of the titanate nanowires before and after modification were observed using a JEOL 2010 transmission electron microscope. Figure 2-1 As shown, the diameter of the titanate nanowires before modification is about 10-20 nm and the length can reach the micrometer level. After modification, the diameter of the titanate nanowires hardly changes, and the

[101] crystal plane size in the crystal structure still indicates that it is anatase TiO2, but the length is reduced.

[0205] Furthermore, under the above conditions, the ultrasonic time for modifying the activated titanate nanowires was changed to 5 minutes, 20 minutes, 40 minutes, and 60 minutes. The resulting products were filtered, washed with water, dried, and accurately weighed. The results showed that the weight gain rates were 3.8%, 8.6%, 6.5%, and 3.2%, respectively, indicating that the modification effect first increased and then decreased with increasing ultrasonic time. The modified titanate nanowires were observed using a JXL30-ESEM scanning electron microscope. Figure 2-2As shown in the figures (top left for 5 minutes, top right for 20 minutes, bottom left for 40 minutes, and bottom right for 60 minutes), the results indicate that the length of titanate nanowires gradually decreases with increasing ultrasonic time. After 60 minutes of ultrasonication, the one-dimensional linear characteristics of the nanowires almost disappear, and the filtrate appears pale blue. This is likely due to the high shear stress of the ultrasonication damaging the titanate nanowires, resulting in fine nanofragments entering the filtrate and leading to a low weight gain rate of the titanate nanowires under these conditions. Therefore, the ultrasonication time for titanate nanowire modification should not be too long.

[0206] Similarly, under the above conditions, the ultrasonic time for modifying the activated titanate nanowires was fixed at 5 minutes and 30 minutes, but the ultrasonic power was changed to 50W, 100W, 300W, 500W, 1000W, 1500W and 2000W. The resulting products were filtered, washed with water, dried and accurately weighed. The product weight gain rate is shown in Table 2-1. It shows that the weight gain rate first increases and then decreases with increasing ultrasonic power at different times. In particular, the weight gain rate is -20.4% after ultrasonication for 30 minutes at high ultrasonic power, indicating that some titanate nanowires have broken into extremely fine nanoparticles and cannot be separated by filtration, thus being lost into the filtrate.

[0207] Table 2-1 Weight gain of modified titanate nanowires after 5 and 30 minutes of sonication at different powers

[0208] Example 2-2 (Activation and Modification Conditions for Titanate Nanowires)

[0209] NaOH aqueous solutions with concentrations of 0.05 mol / L, 0.1 mol / L, 0.25 mol / L, 0.5 mol / L, and 1.0 mol / L were prepared. The titanate nanowires obtained in Example 2-1 were added to the above NaOH aqueous solutions (solid-liquid mass / volume ratio of 1:50) and stirred until homogeneous. Then, an equal volume of 5% hexadecyltrimethylammonium chloride aqueous solution (as in Example 2-1) was added, and the mixture was ultrasonically vibrated at 300 W for 30 minutes. The products were filtered, washed with water, dried, and weighed using a precision balance. The calculated weight gain rates were 3.1%, 7.3%, 1.9%, -10.7%, and -80.2%, respectively. These results indicate that titanate nanowires are more easily destroyed under ultrasonic conditions; therefore, the concentration of strong alkali should not be too high. Based on the results of Example 2-1, the mechanism of titanate nanowire modification may be: strong alkali causes the formation of a hydration layer or negative charge on the surface of titanate nanowires, thereby promoting the adsorption of the positively charged hydrophilic ends of modifiers such as hexadecyltrimethylammonium chloride on the surface, thus modifying the titanate nanowires; however, if the concentration of strong alkali is too high, the ultrasonic time is too long, or the ultrasonic power is too high, the titanate nanowires are easily destroyed and fragmented under the high shear of ultrasound.

[0210] Following the above method, titanate nanowires were activated with 0.1 mol / L KOH and LiOH aqueous solutions, and then ultrasonically vibrated at 300 W for 30 minutes in a hexadecyltrimethylammonium chloride aqueous solution. The products were filtered, washed with water, dried, and weighed using a precision balance. The calculated weight gain rates were 6.4% and 7.9%, respectively, indicating that both KOH and LiOH activation of titanate nanowires can successfully modify them.

[0211] Examples 2-3 (Modifier Types)

[0212] Titanate nanowires were activated with a 0.1 mol / L NaOH aqueous solution according to the method in Example 2-1. Then, 5% aqueous solutions of tetradecyltrimethylammonium chloride, octadecyltrimethylammonium chloride, tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, octadecylammonium bromide, hexadecylpyridine chloride, and dodecylpyridine chloride (equal in volume to those in Example 2-1) were added. The mixture was then ultrasonically vibrated at 300 W for 30 minutes. The products were filtered, washed with water, dried, and weighed using a precision balance. The calculated weight gain rates were 8.2%, 5.9%, 7.8%, 7.4%, 5.5%, 4.7%, and 5.1%, respectively, indicating that long-chain alkyl quaternary ammonium salts can successfully modify titanate nanowires.

[0213] Examples 2-4 (Modified titanate nanowire masterbatch and its content)

[0214] The hexadecyltrimethylammonium chloride-modified titanate nanowires prepared by the method in Example 2-1 were mixed in a certain amount with maleic anhydride-grafted polypropylene (brand name CMG9801, grafting rate 1.0%, Shanghai Rizhisheng New Technology Development Co., Ltd.). After mixing in a mixer, the mixture was extruded and granulated by an internal mixer to obtain a masterbatch. By adjusting the amount of addition, masterbatches with modified titanate nanowire mass contents of 2%, 5%, 10%, 15%, 20%, 25%, and 30% were obtained respectively.

[0215] As the content of modified titanate nanowires increases, the resulting masterbatch particles gradually change from uniform particles with a rounded luster to particles with reduced luster and whitening; when the mass content of modified titanate nanowires is 30%, the masterbatch particles appear as irregular particles. Figure 2-3 The images show masterbatches with 25% and 30% content. The latter shows more severe local whitening, which may be due to uneven dispersion or agglomeration of the modified titanate nanowires. Therefore, it is more appropriate for the mass content of modified titanate nanowires in the masterbatch to be no higher than 25%.

[0216] Examples 2-5 (Content of modified titanate nanowires in BOPP)

[0217] The masterbatch with a modified titanate nanowire content of 10% prepared in Examples 2-4 was mixed with ternary copolymer polypropylene (brand name FS5612, Singapore TPC Company), and then corresponding composite additives used in conventional BOPP film production (2% of the total mass in the final film) such as slip agent, anti-sticking agent (erucamide is used as an example in this example as both slip agent and anti-sticking agent) and antioxidant (BASF composite antioxidant XT500 is used as an example in this example) were added. The mixture was extruded and granulated using a twin-screw extruder to obtain plastic pellets with modified titanate nanowire contents of 0.1%, 0.5%, 1.0%, 2.0%, 4.0%, 6.0%, and 8.0%, respectively. The obtained plastic pellets are added to a biaxially oriented extrusion apparatus for BOPP heat-sealing film production for melting and extrusion casting. The conditions and process are as follows: quench roll temperature is controlled at 30 ℃; longitudinal stretching preheating, longitudinal stretching preheating roll temperature is 80~150 ℃; longitudinal stretching, longitudinal stretching roll temperature is 70~150 ℃; longitudinal stretching shaping roll temperature is 20~80 ℃; longitudinal stretching ratio is 5; transverse stretching preheating temperature is 120~175 ℃; transverse stretching zone temperature is 150~170 ℃; transverse stretching shaping zone temperature is 100~150 ℃; cooling; traction, speed is 200 m / min; winding, tension is 150 N / m. Figure 2-4 The BOPP film has a modified titanate nanowire content of 4.0%. In addition, films were also formed using unmodified titanate nanowire masterbatch, masterbatch with 1.0% unmodified titanate nanowire, and film formed by directly adding 1.0% modified titanate nanowire without masterbatch, using the same extrusion casting and planar biaxial stretching process described above.

[0218] The tensile strength, elongation at break, coefficient of friction, gloss, and haze of the prepared BOPP film were tested according to the national standard GB / T12026-2000. The results are shown in Table 2-2. The results show that the BOPP films prepared by adding unmodified titanate nanowires and by directly adding modified titanate nanowires without using masterbatch have lower mechanical properties such as strength and coefficient of friction than the BOPP film without addition, while having lower gloss and higher haze. In comparison, the BOPP film prepared by adding modified titanate nanowires in the form of masterbatch has improved longitudinal and transverse tensile strength and elongation at break, reduced coefficient of friction, almost unchanged gloss, and reduced haze.

[0219] The above results show that: (1) The modified titanate nanowires and maleic anhydride-grafted polypropylene were mixed to obtain a masterbatch, which achieved the initial uniform dispersion of the modified titanate nanowires; after the masterbatch was mixed with ternary copolymer polypropylene and granulated, the good dispersibility of the modified titanate nanowires was further improved, and their agglomeration was avoided; (2) The one-dimensional titanate nanowires with a large aspect ratio were also oriented in both the length and width directions of the film plane during the biaxial stretching process in the manufacturing of BOPP film, thereby achieving biaxial reinforcement of BOPP film in both the longitudinal and transverse directions; (3) The oriented modified titanate nanowires reduced their friction coefficient, thereby improving their scratch resistance; (4) The oriented modified titanate nanowires were uniformly dispersed and had little effect on the gloss reduction, but reduced their haze, that is, improved their transparency; (5) When the modified titanate nanowires were too high, all their properties tended to decrease.

[0220] Table 2-2: Test results of different BOPP films

[0221] Scanning electron microscopy revealed that the BOPP film containing 1.0% modified titanate nanowires exhibited agglomeration in the film, even with the addition of unmodified titanate nanowires. Figure 2-5 (Left), but the modified titanate nanowires, after being treated with masterbatch, did not agglomerate and showed significant orientation when added. Figure 2-5 (right), such as Figure 2-5 As shown. Further observation of the BOPP film with modified titanate nanowires added via masterbatch using transmission electron microscopy was conducted, as shown. Figure 2-6 This further confirms that the acid salt nanowires have a dominant orientation in two nearly mutually perpendicular directions in the BOPP film.

[0222] BOPP films without additives and BOPP films with 1.0% modified titanate nanowires added via masterbatch method were observed using a Japanese Olympus BX53 polarizing microscope. The results are as follows: Figure 2-7 As shown: The additive-free BOPP film exhibits a typical spherulite black cross extinction phenomenon. Figure 2-7 (Left) The grain size is relatively large; after adding modified titanate nanowires, the grain size is significantly reduced but the number increases. Figure 2-7 (Right). This indicates that the modified titanate nanowires induced the crystallization of polypropylene to form more but smaller grains, which may be the main reason for the improved mechanical properties and gloss, reduced haze, and improved transparency of BOPP films.

[0223] Furthermore, the melting point of the above samples was characterized by programmed temperature rise under a nitrogen atmosphere using a Netzsch DSC 204 F1 differential scanning calorimeter. Figure 2-8As shown, during the heating process, the unmodified BOPP film exhibited a melting point close to 169°C, but this gradually decreased with increasing amounts of modified titanate nanowires, exhibiting multiple melting peaks. It is worth mentioning that when BOPP film is used as a heat-sealing film, it is achieved by first heating it to near its melting point to allow the polypropylene molecular chains on the two contacting film surfaces to intertwine, and then cooling it to fix this molecular chain intertwine to achieve heat sealing. The lower melting point and crystallization temperature of the reinforced polypropylene film measured by DSC above indicate that this modified titanate nanowire-reinforced BOPP film can achieve thermal melting and molecular chain intertwine at lower temperatures, i.e., heat sealing at lower temperatures. Therefore, this nanomaterial-reinforced polypropylene film has significant potential in the packaging film field, especially in the heat-sealing film sector.

[0224] Example 3-1 (Alkali Treatment)

[0225] Following the method described in the literature (Nanoscale, 2013, 5, 5519), 2.5 g of anatase TiO2 was added to 200 mL of 10 mol / L NaOH aqueous solution. After thorough mixing, the mixture was added to a hydrothermal reactor and reacted at 90°C for 48 hours. After the reaction was completed, the mixture was allowed to cool naturally to room temperature. The product was filtered and washed with 0.1 mol / L HCl and deionized water until the pH reached approximately 1.0. After drying, titanate nanosheets were obtained.

[0226] (1) Weigh the prepared titanate nanosheets using a precision balance, add them to a 0.1 mol / L NaOH aqueous solution, and stir for 10 min, 30 min, 1 h, and 2 h, with a solid-liquid mass / volume ratio of 1:50 (g / mL). Then, add the treated mixture dropwise to a 5% hexadecyltrimethylammonium chloride aqueous solution (the mass-to-volume ratio of titanate nanosheets is 1:50 (g / mL)). Stir until homogeneous and react for 30 minutes. The product is filtered, washed three times with water, dried, and weighed using a precision balance. Weight gain % = (M 后 -M 前 ) / M 前 x100%, where M 后 M represents the mass of the modified titanate nanosheets. 前The values ​​represent the mass of the titanate nanosheets before modification. The results showed that the weight gain rates of the titanate nanosheets after treatment with NaOH aqueous solution for 10 min, 30 min, 1 h, and 2 h were 1.1%, 10.4%, 8.3%, and 3.6%, respectively. In the control experiment, titanate nanosheets of the same mass were dispersed in an equal volume of deionized water (equal to the NaOH aqueous solution) and then directly added dropwise to an equal volume of a 5% (w / v) hexadecyltrimethylammonium chloride aqueous solution. After treatment under the same conditions, the weight gain rate was accurately weighed, showing a rate of 0.97%. This result indicates that alkali treatment is beneficial for the modification of titanate nanosheets. Raman spectroscopy was performed on the titanate nanosheets treated with different alkali times, and the results are shown below. Figure 3-1 As shown, the products of titanate nanosheets treated for 2 hours exhibit layered structures at 560 and 706 cm⁻¹. -1 The slight decrease in peak intensity indicates that the treatment time was too long, which caused the titanate nanosheets to be destroyed. This is consistent with the above results on weight gain, which suggests that the alkali treatment time should not be too long, preferably 30 min to 1 h.

[0227] (2) Further, the same amount of titanate nanosheets as described above were added to equal volumes of 0.01 mol / L, 0.05 mol / L, 0.10 mol / L, 0.15 mol / L, 0.20 mol / L, and 0.25 mol / L NaOH aqueous solutions, respectively, and stirred for 10 min. It was observed that the titanate nanosheets gradually turned into a pale blue transparent liquid in NaOH solutions with concentrations of 0.20 mol / L and 0.25 mol / L, while the rest remained a milky white suspension. Figure 3-2 As shown, this indicates that increasing the alkali concentration reduces the size of the titanate nanosheets. Based on the aforementioned control experiments, the concentration of the strong alkali is 0.01-0.15 mol / L, preferably 0.05-0.1 mol / L.

[0228] (3) Further, prepare a 0.10 mol / L KOH and LiOH aqueous solution, and stir for 30 min. Modify titanate nanosheets using the method in (1) above. The weight gain rates are 11.2% and 8.9%, respectively, indicating successful modification.

[0229] Example 3-2 (Modifier)

[0230] Following the method in Example 3-1 (1), titanate nanosheets were treated with a 0.1 mol / L NaOH aqueous solution for 30 min, and then added dropwise to a 5% (w / v) hexadecyltrimethylammonium chloride aqueous solution. After stirring for a certain period of time, the supernatant was collected, centrifuged, and its concentration was determined by ultraviolet spectrophotometer at a wavelength of 270 nm. The decrease in the concentration of hexadecyltrimethylammonium chloride in the supernatant reflects the increase in the adsorption capacity of titanate nanosheets. The results are as follows: Figure 3-3 As shown, the concentration of hexadecyltrimethylammonium chloride decreased significantly after 10 minutes, approached its lowest point after 30 minutes, and reached its lowest point after 60 minutes; therefore, based on efficiency factors, the optimal reaction time is 20 min to 5 h.

[0231] Titanate nanosheets were treated with a 0.1 mol / L NaOH aqueous solution for 30 min according to the method in Example 3-1 (1). Then, solutions of tetradecyltrimethylammonium chloride, octadecyltrimethylammonium chloride, tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, octadecylammonium bromide, hexadecylpyridine chloride, and dodecylpyridine chloride with a mass / volume concentration of 5% were added respectively. After stirring and reacting for 30 min, the products were filtered, washed with water three times, dried, and weighed using a precision balance. The results showed that the weight gain rates were 11.6%, 9.7%, 12.3%, 10.9%, 8.9%, 9.1%, and 9.8%, respectively, indicating that different modifiers could successfully modify titanate nanosheets. The hexadecyltrimethylammonium bromide modified product was observed by transmission electron microscopy, and the results are as follows. Figure 3-4 As shown, the surface of the titanate nanosheets is covered with an amorphous material after modification, indicating that the modification was successful.

[0232] Example 3-3 (Masterbatch and its content)

[0233] Titanate nanosheets were treated with a 0.1 mol / L NaOH aqueous solution for 30 min according to the method in Example 3-1 (1), and modified titanate nanosheets were prepared using hexadecyltrimethylammonium chloride as a surfactant modifier. The modified titanate nanosheets were mixed with maleic anhydride-grafted polypropylene (brand name CMG9801, grafting rate 1.0%, Shanghai Rizhisheng New Technology Development Co., Ltd.), and after mixing in a mixer, the mixture was extruded and granulated by a kneading mill to obtain a masterbatch. The amount of maleic anhydride-grafted polypropylene added was adjusted to obtain masterbatches with modified titanate nanosheet mass contents of 5%, 10%, 15%, 20%, and 25%, respectively. As the modified titanate nanosheet content increased, the obtained masterbatch particles gradually changed from uniform particles with a rounded luster to particles with reduced luster and whitening; when the modified titanate nanosheet mass content was 25%, the masterbatch particles showed particles with fine cracks. The results indicate that a modified titanate nanosheet content of no more than 20% in the masterbatch is appropriate; if the content of modified titanate nanosheets in the masterbatch is too high, cracks will appear in the particles due to macroscopic phase separation, that is, uneven dispersion and agglomeration of modified titanate nanosheets.

[0234] The modified titanate nanosheets were set to have a mass content of 1.0% in the final film. The masterbatches with mass contents of 5%, 10%, 15%, and 20% of the modified titanate nanosheets were mixed with ternary copolymer polypropylene (brand name FS5612, Singapore TPC Company) respectively. Then, slip agents, anti-sticking agents (erucamide is used as an example in this embodiment as both slip agent and anti-sticking agent), antioxidants (BASF composite antioxidant XT500 is used as an example in this embodiment) and other corresponding composite additives used in conventional BOPP film production (2% of the total mass in the final film) were added. The mixture was then extruded and granulated into plastic pellets using a twin-screw extruder. The obtained plastic pellets were added to a biaxially oriented extrusion apparatus for BOPP heat-sealable film production for melting and extrusion casting. The conditions and process were as follows: quench roll temperature controlled at 30℃; longitudinal stretching preheating, longitudinal stretching preheating roll temperature 80–150℃; longitudinal stretching, longitudinal stretching roll temperature 70–150℃; longitudinal stretching shaping roll temperature 20–80℃; longitudinal stretching ratio 5; transverse stretching preheating temperature 120–175℃; transverse stretching zone temperature 150–170℃; transverse stretching shaping zone temperature 100–150℃; cooling; traction speed 200 m / min; winding tension 150 N / m. In addition, control experiments were conducted including: films made without titanate nanosheets, without modified titanate nanosheets, and with modified titanate nanosheets added directly without masterbatch, using the same extrusion casting and planar biaxial stretching process. Photographs of the resulting films are shown below. Figure 3-5 As shown: among them, the BOPP films prepared by adding unmodified titanate nanosheets and those prepared by directly adding modified titanate nanosheets without using masterbatch show local opacity; the rest of the BOPP films are transparent and uniform film materials.

[0235] The tensile strength, elongation at break, and gloss of the prepared BOPP film were tested using the national standard GB / T12026-2000. The water vapor transmission rate of the prepared BOPP film was further tested using the national standard GB / T 26253-2010, and the results are shown in Table 3-1. The results show that the BOPP films prepared with unmodified titanate nanosheets and those prepared by directly adding modified titanate nanosheets without masterbatch have lower mechanical properties such as strength than the BOPP film without modification, and also have lower gloss. In comparison, the BOPP film prepared by adding modified titanate nanosheets in the form of masterbatch shows improved longitudinal and transverse tensile strength and elongation at break, while the gloss remains almost unchanged, and the water vapor transmission rate decreases.

[0236] The above results demonstrate that: the masterbatch prepared by mixing modified titanate nanosheets with maleic anhydride-grafted polypropylene achieves the initial uniform dispersion of titanate nanosheets; the granulation of the masterbatch with ternary copolymer polypropylene further improves the good dispersibility of titanate nanosheets and avoids their agglomeration; the white or light-colored appearance of titanate nanosheets does not affect the transparency and gloss of the packaging film; the well-dispersed titanate nanosheets easily form a dense barrier layer in the BOPP matrix, effectively extending the diffusion path of gas and water molecules and significantly improving the barrier performance of the packaging film.

[0237] Table 3-1: Test results of different BOPP films

[0238] Examples 3-4 (Content of modified titanate nanosheets)

[0239] Using the method in Example 3-1 (1), titanate nanosheets were treated with a 0.1 mol / L NaOH aqueous solution for 30 min, and modified titanate nanosheets were prepared using hexadecyltrimethylammonium bromide as a surfactant modifier. Using the method in Example 3-3, a masterbatch with a modified titanate nanosheet content of 10% was first prepared, mixed with ternary copolymer polypropylene (brand name FS5612, Singapore TPC Company), and then corresponding composite additives used in conventional BOPP film production, such as slip agents, anti-adhesion agents, and antioxidants (2% of the total mass in the final film), were added. The mixture was extruded and granulated using a twin-screw extruder to obtain plastic pellets with modified titanate nanosheet contents of 0.05%, 0.1%, 0.2%, 0.5%, 1.0%, 3.0%, 5.0%, and 8.0%, respectively. The obtained plastic pellets were still processed into films using the process in Example 3-3, and tested. The results are shown in Table 3-2 below. The results showed that: (1) the mechanical properties of BOPP film first increased and then decreased with the increase of modified titanate nanosheet content; (2) the improvement effect was significant when the amount of modified titanate nanosheet added exceeded 0.2%; (3) the mechanical properties of BOPP film decreased and the gloss decreased when the amount of modified titanate nanosheet added reached 8.0%; (4) the water vapor permeability of BOPP film increased significantly when the amount of modified titanate nanosheet added reached 3.0% or more. Considering all factors, the preferred amount of modified titanate nanosheet added to BOPP film is 0.2%-5.0%; more preferably 1.0%-5.0%.

[0240] Table 3-2: Test results of BOPP films containing different contents of modified titanate nanosheets

[0241] The above samples were subjected to programmed heating and cooling under a nitrogen atmosphere using a Netzsch DSC 204 F1 differential scanning calorimeter to characterize their melting point and crystallization temperature. Figure 3-6 As shown, the DSC cooling curves of BOPP without additives exhibit a higher crystallization peak at a weaker temperature. However, for the sample with added titanate nanosheets, if the nanosheets effectively nucleate, the polypropylene molecular chains crystallize more rapidly during cooling, resulting in a lower crystallization temperature observed on the DSC curve. This indicates that the addition of nanosheets improves the crystallization rate and crystallinity of polypropylene. During heat sealing, the film needs to be heated to near its softened state to allow adjacent polypropylene molecules to fuse together, followed by cooling to solidify and form a strong bond. The decrease in crystallization temperature in the DSC test indicates that titanate nanosheet composite BOPP can achieve effective fusion at a lower temperature during the heat sealing process, thus facilitating more complete melting and recrystallization at a lower heat sealing temperature. This improves sealing quality and strength, reduces energy consumption, and is beneficial for process control and product quality stability.

[0242] Further observation was conducted using a Japanese Olympus BX53 polarizing microscope on the unmodified BOPP film and BOPP films with modified titanate nanosheets added at levels of 1.0%, 3.0%, and 5.0%. The results are as follows: Figure 3-7 As shown, the unmodified BOPP film exhibits a large spherulite size, while the spherulite diameter decreases with increasing modified titanate nanosheet content. It is well known that the crystallization process includes nucleation and crystal growth. In the unmodified BOPP film, spherulites mainly form through uniform nucleation, meaning that nucleus formation is slow and few in number, allowing for sufficient crystal growth and the formation of large spherulites. However, in the modified titanate nanosheet composite BOPP film, the introduction of nanosheets alters the nucleation mechanism, promoting non-uniform nucleation of spherulites. Due to the rapid generation of numerous nuclei, spherulite growth is limited, preventing expansion to larger sizes, resulting in significantly smaller spherulite sizes compared to the unmodified BOPP film. Modified titanate nanosheets, acting as nucleating agents, improve the crystallization rate and microstructure uniformity of the BOPP film, potentially becoming a key factor in enhancing its mechanical properties and improving heat-sealing performance.

[0243] Examples 3-5 (Dispersibility of modified titanate nanosheets)

[0244] Modified titanate nanosheet masterbatch was prepared using the methods described in Examples 3-4. This masterbatch was then mixed with heat-sealable polypropylene raw material (RP129K) in a specific ratio, maintaining other process parameters to prepare BOPP films. The samples were observed using a transmission electron microscope. Figure 3-8The results show that the modified titanate nanosheets are dispersed very uniformly in the polypropylene matrix, with almost no obvious agglomeration. This characterization result proves that the preparation method can effectively improve the dispersibility of titanate nanosheets in polypropylene, thereby providing a uniform and stable nanofiller distribution for BOPP film reinforcement, which in turn helps to improve the overall mechanical and heat-sealing properties of the film.

[0245] Examples 3-6 (UV shielding of modified titanate nanosheets)

[0246] Modified titanate nanosheets were prepared using the methods described in Examples 3-4. These nanosheets were then mixed with maleic anhydride-grafted polypropylene (grade ST868M) to prepare a masterbatch, which was subsequently used to prepare BOPP films with modified titanate nanosheet contents of 3.0% and 5.0% in the final film material, also using the methods described in Examples 3-4. The transmission spectra of each BOPP film sample were measured using a UV-Vis spectrophotometer (PerkinElmer Lambda 950) in the wavelength range of 200-400 nm. Figure 3-9 As shown, the unmodified BOPP film exhibits low absorbance in the 200-400 nm UV band, while the UV absorbance of the film significantly increases with the increase of modified titanate nanosheet content, especially in the 200-300 nm band, where it demonstrates strong UV absorption. This property contributes to the degradation resistance of this BOPP film after use.

[0247] Furthermore, BOPP film samples with different formulations were placed in a UV aging test chamber and subjected to UV aging tests at 60 ℃ using a UVA-340 fluorescent UV lamp, according to GB / T 16422.3-2014 standard, with cumulative exposure times of 10, 20, 40, 60, and 80 h. Samples were periodically removed, and the color change (ΔE) before and after aging was measured using a colorimeter (Konica Minolta CM-3600A). The tensile strength retention rate was tested using an electronic tensile testing machine (Instron 5967). The results are shown in Table 3-3. The introduction of modified titanate nanosheets significantly improved the UV aging performance of the BOPP film. After 80 h of UV aging, the color change (ΔE) of the unmodified BOPP film was 19.5, mechanical properties declined, and the tensile strength retention rate was 84%. The ΔE values ​​of BOPP films with 3% and 5% modified titanate nanosheets reached 40.2 and 45.8, respectively, and the tensile strength retention rates decreased to 37% and 24%, respectively, indicating that the modified titanate nanosheets can effectively absorb ultraviolet light and promote yellowing and degradation.

[0248] Table 3-3: UV aging test results of BOPP film samples with different formulations

[0249] The above description is merely a preferred embodiment of the present invention, and therefore should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made in accordance with the scope of the patent and the contents of the specification should still fall within the scope of the present invention.

Claims

1. A BOPP composite film masterbatch comprising modified titanate nanotubes, modified titanate nanowires, or modified titanate nanoplates, wherein, The modified titanate nanotubes are titanate nanotubes with surfactants adsorbed on their surfaces, the modified titanate nanowires are titanate nanowires with surfactants adsorbed on their surfaces, and the modified titanate nanosheets are titanate nanosheets with surfactants coated on their surfaces. When the BOPP composite membrane masterbatch contains modified titanate nanotubes, the mass fraction of the modified titanate nanotubes in the BOPP composite membrane masterbatch is 10%-20%. When the BOPP composite membrane masterbatch contains modified titanate nanowires, the mass fraction of the modified titanate nanowires in the BOPP composite membrane masterbatch is 2%-25%. When the BOPP composite membrane masterbatch contains modified titanate nanosheets, the mass fraction of the modified titanate nanosheets in the BOPP composite membrane masterbatch is 5%-20%. The modified titanate nanotubes are obtained by activating titanate nanotubes with a strong alkali and then mixing them with a surfactant. The modified titanate nanowires are obtained by activating titanate nanowires with a strong alkali and then mixing them with a surfactant. The modified titanate nanosheets are obtained by activating titanate nanosheets with a strong alkali and then mixing them with a surfactant.

2. The BOPP composite film masterbatch according to claim 1, wherein, When the BOPP composite membrane masterbatch contains modified titanate nanotubes, the mass fraction of the modified titanate nanotubes in the BOPP composite membrane masterbatch is 15%.

3. The BOPP composite film masterbatch according to claim 1, wherein, When the BOPP composite membrane masterbatch contains modified titanate nanowires, the mass fraction of the modified titanate nanowires in the BOPP composite membrane masterbatch is 5-20%.

4. The BOPP composite film masterbatch according to claim 1, wherein, When the BOPP composite membrane masterbatch contains modified titanate nanowires, the mass fraction of the modified titanate nanowires in the BOPP composite membrane masterbatch is 10%.

5. The BOPP composite film masterbatch according to claim 1, wherein, When the BOPP composite membrane masterbatch contains modified titanate nanosheets, the mass fraction of the modified titanate nanosheets in the BOPP composite membrane masterbatch is 10%-20%.

6. The BOPP composite film masterbatch according to claim 1, wherein, The modified titanate nanotubes were prepared by the following method: (1) The titanate nanotubes are first mixed with a strong alkaline aqueous solution; (2) The mixture obtained from the first mixing is then mixed with a surfactant in a second mixing process; (3) The mixture obtained by the second mixing is filtered, washed with water and dried to obtain modified titanate nanotubes.

7. The BOPP composite film masterbatch according to claim 1, wherein, The modified titanate nanowires were prepared by the following method: (1) The titanate nanowires are first mixed with a strong alkaline aqueous solution; (2) The mixture obtained from the first mixing is then mixed with a surfactant in a second mixing process; (3) The mixture obtained by the second mixing is filtered, washed with water and dried to obtain modified titanate nanowires.

8. The BOPP composite film masterbatch according to claim 1, wherein, The modified titanate nanosheets were prepared by the following method: (1) The titanate nanosheets are first mixed with a strong alkaline aqueous solution; (2) The mixture obtained from the first mixing is then mixed with a surfactant in a second mixing process; (3) The mixture obtained by the second mixing is filtered, washed with water and dried to obtain modified titanate nanosheets.

9. The BOPP composite film masterbatch according to claim 6, wherein, The method for preparing the modified titanate nanotubes further comprises one or more technical features selected from (i)-(ii): (i) In the strong base aqueous solution, the concentration of the strong base is 0.1-0.5 mol / L; (ii) The second mixing is performed under ultrasonic conditions.

10. The BOPP composite film masterbatch according to claim 9, wherein, In the strong alkali aqueous solution, the concentration of the strong alkali is 0.3-0.5 mol / L.

11. The BOPP composite film masterbatch according to claim 9, wherein, The concentration of the strong base in the aqueous solution is 0.3 mol / L.

12. The BOPP composite film masterbatch according to claim 9, wherein, The power of the ultrasound is 100W-1000W.

13. The BOPP composite film masterbatch according to claim 9, wherein, The power of the ultrasound is 100W-500W.

14. The BOPP composite film masterbatch according to claim 9, wherein, The power of the ultrasound is 300W.

15. The BOPP composite film masterbatch according to claim 7, wherein, The method for preparing the modified titanate nanowires further comprises one or more technical features selected from (i)-(ii): (i) In the strong base aqueous solution, the concentration of the strong base is 0.05-1 mol / L; (ii) The second mixing is performed under ultrasonic conditions.

16. The BOPP composite film masterbatch according to claim 15, wherein, In the strong alkali aqueous solution, the concentration of the strong alkali is 0.05-0.25 mol / L.

17. The BOPP composite film masterbatch according to claim 15, wherein, In the strong alkali aqueous solution, the concentration of the strong alkali is 0.1-0.2 mol / L.

18. The BOPP composite film masterbatch according to claim 15, wherein, In the strong alkali aqueous solution, the concentration of the strong alkali is 0.1 mol / L.

19. The BOPP composite film masterbatch according to claim 15, wherein, The power of the ultrasound is 50W-2000W.

20. The BOPP composite film masterbatch according to claim 15, wherein, The power of the ultrasound is 50W-1500W.

21. The BOPP composite film masterbatch according to claim 15, wherein, The power of the ultrasound is 100W-1000W.

22. The BOPP composite film masterbatch according to claim 15, wherein, The power of the ultrasound is 300W.

23. The BOPP composite film masterbatch according to claim 15, wherein, The ultrasound session lasted 5 to 60 minutes.

24. The BOPP composite film masterbatch according to claim 15, wherein, The ultrasound duration is 5-40 minutes.

25. The BOPP composite film masterbatch according to claim 15, wherein, The ultrasound session lasted 20-40 minutes.

26. The BOPP composite film masterbatch according to claim 15, wherein, The ultrasound session lasted for 30 minutes.

27. The BOPP composite film masterbatch according to claim 8, wherein, The method for preparing the modified titanate nanosheets further comprises one or more technical features selected from (i)-(iii): (i) In the strong base aqueous solution, the concentration of the strong base is 0.01-0.25 mol / L; (ii) The first mixing time is 10 min to 2 h; (iii) The second mixing time is 10 min to 48 h.

28. The BOPP composite film masterbatch according to claim 27, wherein, In the strong alkali aqueous solution, the concentration of the strong alkali is 0.01-0.15 mol / L.

29. The BOPP composite film masterbatch according to claim 27, wherein, In the strong alkali aqueous solution, the concentration of the strong alkali is 0.05-0.1 mol / L.

30. The BOPP composite film masterbatch according to claim 27, wherein, In the strong alkali aqueous solution, the concentration of the strong alkali is 0.1 mol / L.

31. The BOPP composite film masterbatch according to claim 27, wherein, The first mixing time is 30 min to 1 h.

32. The BOPP composite film masterbatch according to claim 27, wherein, The first mixing time is 30 minutes.

33. The BOPP composite film masterbatch according to claim 27, wherein, The second mixing time is 20 min to 5 h.

34. The BOPP composite film masterbatch according to claim 27, wherein, The second mixing time is 30-60 minutes.

35. The BOPP composite film masterbatch according to claim 27, wherein, The second mixing time is 30 minutes.

36. The BOPP composite film masterbatch according to claim 1, wherein, The surfactant is selected from one or more long-chain alkyl quaternary ammonium salts containing 12 or more carbon atoms.

37. The BOPP composite film masterbatch according to claim 36, wherein, The surfactant is selected from tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, octadecylammonium chloride, tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, octadecylammonium bromide, hexadecylpyridine chloride, dodecylpyridine chloride, or any combination thereof.

38. The BOPP composite film masterbatch according to claim 36, wherein, The surfactant is tetradecyltrimethylammonium bromide.

39. The BOPP composite film masterbatch according to claim 36, wherein, The surfactant is hexadecyltrimethylammonium chloride.

40. The BOPP composite film masterbatch according to claim 1, wherein, The strong base is selected from sodium hydroxide, potassium hydroxide, lithium hydroxide, or any combination thereof.

41. The BOPP composite film masterbatch according to claim 40, wherein, The strong base is sodium hydroxide.

42. The BOPP composite film masterbatch according to claim 6, wherein, The method for preparing the modified titanate nanotubes further comprises one or more of the following technical features selected from (i)-(iv): (i) In the first mixture, the ratio of the mass of the titanate nanotubes to the volume of the strong alkaline aqueous solution is 1 / 40 to 1 / 60 g / mL; (ii) In the second mixture, the surfactant is provided in the form of an aqueous solution; (iii) The first mixing time is 0.5-5 hours; (iv) In the second mixture, the ultrasound time is 5 to 30 minutes.

43. The BOPP composite film masterbatch according to claim 42, wherein, In the first mixture, the mass ratio of the titanate nanotubes to the volume of the strong alkaline aqueous solution is 1 / 50 g / mL.

44. The BOPP composite film masterbatch according to claim 42, wherein, In the aqueous solution of the surfactant, the mass-volume concentration of the surfactant is 3-8% (w / v).

45. The BOPP composite film masterbatch according to claim 42, wherein, In the aqueous solution of the surfactant, the mass-volume concentration of the surfactant is 5% (w / v).

46. ​​The BOPP composite film masterbatch according to claim 42, wherein, The mass ratio of the titanate nanotubes to the volume of the aqueous solution of the surfactant is 1 / 40 to 1 / 60 g / mL.

47. The BOPP composite film masterbatch according to claim 42, wherein, The mass ratio of the titanate nanotubes to the volume of the aqueous solution of the surfactant is 1 / 50 g / mL.

48. The BOPP composite film masterbatch according to claim 42, wherein, The first mixing time is 1 hour.

49. The BOPP composite film masterbatch according to claim 42, wherein, In the second mixing, the ultrasound duration is 10 minutes.

50. The BOPP composite film masterbatch according to claim 7, wherein, The method for preparing the modified titanate nanowires further comprises one or more technical features selected from (i)-(iii): (i) In the first mixture, the mass ratio of the titanate nanowires to the volume of the strong alkaline aqueous solution is 1 / 40 to 1 / 60 g / mL; (ii) In the second mixture, the surfactant is provided in the form of an aqueous solution; (iii) The first mixing time is 0.5-5 hours.

51. The BOPP composite film masterbatch according to claim 50, wherein, In the first mixture, the mass ratio of the titanate nanowires to the volume of the strong alkaline aqueous solution is 1 / 50 g / mL.

52. The BOPP composite film masterbatch according to claim 50, wherein, In the aqueous solution of the surfactant, the mass-volume concentration of the surfactant is 3-8% (w / v).

53. The BOPP composite film masterbatch according to claim 50, wherein, In the aqueous solution of the surfactant, the mass-volume concentration of the surfactant is 5% (w / v).

54. The BOPP composite film masterbatch according to claim 50, wherein, The mass ratio of the titanate nanowires to the volume of the aqueous solution of the surfactant is 1 / 80 to 1 / 120 g / mL.

55. The BOPP composite film masterbatch according to claim 50, wherein, The mass ratio of the titanate nanowires to the volume of the aqueous solution of the surfactant is 1 / 100 g / mL.

56. The BOPP composite film masterbatch according to claim 50, wherein, The first mixing time is 1 hour.

57. The BOPP composite film masterbatch according to claim 8, wherein, The method for preparing the modified titanate nanosheets further comprises one or more technical features selected from (i)-(ii): (i) In the first mixture, the mass ratio of the titanate nanosheets to the volume of the strong alkaline aqueous solution is 1 / 40 to 1 / 60 g / mL; (ii) In the second mixture, the surfactant is provided in the form of an aqueous solution.

58. The BOPP composite film masterbatch according to claim 57, wherein, In the first mixture, the mass ratio of the titanate nanosheets to the volume of the strong alkaline aqueous solution is 1 / 50 g / mL.

59. The BOPP composite film masterbatch according to claim 57, wherein, In the aqueous solution of the surfactant, the mass-volume concentration of the surfactant is 3-8% (w / v).

60. The BOPP composite film masterbatch according to claim 57, wherein, In the aqueous solution of the surfactant, the mass-volume concentration of the surfactant is 5% (w / v).

61. The BOPP composite film masterbatch according to claim 57, wherein, The mass ratio of the titanate nanosheets to the volume of the aqueous solution of the surfactant is 1 / 40 to 1 / 60 g / mL.

62. The BOPP composite film masterbatch according to claim 57, wherein, The mass ratio of the titanate nanosheets to the volume of the aqueous solution of the surfactant is 1 / 50 g / mL.

63. The BOPP composite film masterbatch according to any one of claims 1-62, wherein, The BOPP composite film masterbatch also includes a carrier material.

64. The BOPP composite film masterbatch according to claim 63, wherein, The carrier material is polypropylene.

65. The BOPP composite film masterbatch according to claim 63, wherein, The carrier material is maleic anhydride-grafted polypropylene.

66. The BOPP composite film masterbatch according to claim 63, wherein, The masterbatch is obtained by mixing the modified titanate nanotubes, the modified titanate nanowires, or the modified titanate nanosheets with the carrier material in a mixer and then extruding and granulating them using a kneading machine.

67. A BOPP composite film, wherein the raw material comprises: the masterbatch described in any one of claims 1-66.

68. The BOPP composite film according to claim 67, wherein, When the masterbatch contains modified titanate nanotubes, the mass fraction of the modified titanate nanotubes in the BOPP composite film is 0.05%-6.0%.

69. The BOPP composite membrane according to claim 67, wherein, When the masterbatch contains modified titanate nanotubes, the mass fraction of the modified titanate nanotubes in the BOPP composite film is 0.5%-6.0%.

70. The BOPP composite membrane according to claim 67, wherein, When the masterbatch contains modified titanate nanotubes, the mass fraction of the modified titanate nanotubes in the BOPP composite film is 1.0%-4.0%.

71. The BOPP composite film according to claim 67, wherein, When the masterbatch contains modified titanate nanotubes, the mass fraction of the modified titanate nanotubes in the BOPP composite film is 4.0%.

72. The BOPP composite membrane according to claim 67, wherein, When the masterbatch contains modified titanate nanowires, the mass fraction of the modified titanate nanowires in the BOPP composite film is 0.1%-8.0%.

73. The BOPP composite film according to claim 67, wherein, When the masterbatch contains modified titanate nanowires, the mass fraction of the modified titanate nanowires in the BOPP composite film is 0.5%-6.0%.

74. The BOPP composite membrane according to claim 67, wherein, When the masterbatch contains modified titanate nanowires, the mass fraction of the modified titanate nanowires in the BOPP composite film is 1.0%-6.0%.

75. The BOPP composite membrane according to claim 67, wherein, When the masterbatch contains modified titanate nanowires, the mass fraction of the modified titanate nanowires in the BOPP composite film is 4.0%.

76. The BOPP composite film according to claim 67, wherein, When the masterbatch contains modified titanate nanosheets, the mass fraction of the modified titanate nanosheets in the BOPP composite film is 0.05%-8.0%.

77. The BOPP composite membrane according to claim 67, wherein, When the masterbatch contains modified titanate nanosheets, the mass fraction of the modified titanate nanosheets in the BOPP composite film is 0.2%-5.0%.

78. The BOPP composite film according to claim 67, wherein, When the masterbatch contains modified titanate nanosheets, the mass fraction of the modified titanate nanosheets in the BOPP composite film is 1.0%-5.0%.

79. The BOPP composite membrane according to claim 67, wherein, The raw materials for the BOPP composite film also include the main material and additives.

80. The BOPP composite membrane according to claim 79, wherein, The main material is polypropylene.

81. The BOPP composite membrane according to claim 79, wherein, The main material is ternary copolymer polypropylene or heat-sealing polypropylene.

82. The BOPP composite membrane according to claim 79, wherein, The additives include slip agents, anti-adhesion agents, antioxidants, or any combination thereof.

83. The BOPP composite membrane according to claim 79, wherein, The mass fraction of the additives in the BOPP composite film is 1%-5%.

84. The BOPP composite film according to claim 79, wherein, The mass fraction of the additives in the BOPP composite film is 2%.

85. The BOPP composite membrane according to claim 79, wherein, The BOPP composite membrane is prepared by the following method: (1) The masterbatch, the main material and the additives are mixed and then extruded and granulated using a twin-screw extruder to obtain plastic pellets; (2) The BOPP composite film is obtained by extrusion casting and planar biaxial stretching of the plastic rice.

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