A renewable bopp film, a preparation process and application thereof

Abstract

The application belongs to the technical field of plastic films, and specifically provides a renewable BOPP film, a preparation process and application thereof. The renewable BOPP film comprises an upper surface layer, a core layer and a lower surface layer, the upper surface layer and the lower surface layer are added with an anti-sticking master batch obtained by mixing and granulating homopolypropylene, maleic anhydride grafted polypropylene and composite fibers, and the composite fibers are composed of polyphenylene sulfide-nylon base fibers and silicon dioxide and gel microspheres attached to the surface of the polyphenylene sulfide-nylon base fibers. The renewable BOPP film prepared by the application has the advantages of good wear resistance and mechanical properties.

Description

Technical Field

[0001] This application belongs to the field of plastic film technology, and in particular relates to a renewable BOPP film, its preparation process and its application. Background Technology

[0002] Biaxially oriented polypropylene (BOPP) film, as an important polymer material, occupies a key position in modern industry due to its excellent optical properties, chemical stability, and cost advantages. BOPP film is a thin film material produced by melt-extruding polypropylene resin into thick sheets and then biaxially stretching it in both the longitudinal and transverse directions. During the stretching process, its molecular chains form an ordered arrangement, thus endowing the film with high crystallinity and mechanical strength. Compared to unstretched polypropylene film, BOPP film exhibits significantly improved overall performance, making it one of the preferred materials in industries such as packaging, electronics, and printing.

[0003] In the field of daily necessities packaging film, the application of BOPP film can be subdivided into several branches. In food-related daily necessities, it is often used as snack packaging bags, bread outer films, etc., thanks to its high transparency showcasing the food's color, and its good sealing properties delaying oxidation. For example, potato chip bags use BOPP composite film for moisture protection and freshness preservation. In personal care daily necessities, BOPP material is often used for the label films on shampoo and shower gel bottles. Its excellent printing performance clearly presents product information, and its water resistance allows it to adapt to humid environments. In household cleaning daily necessities, BOPP film is commonly used for the outer packaging bags of dishwashing liquid and laundry detergent, possessing a certain degree of chemical resistance to resist the corrosive effects of cleaning agents. Furthermore, in the individual packaging of small daily necessities such as toothbrushes and combs, BOPP film reduces packaging costs due to its thinness while providing dust protection.

[0004] However, BOPP film still faces some challenges in packaging applications, limiting its further expansion in the high-end packaging sector. In terms of toughness, conventional BOPP film is prone to embrittlement at low temperatures and easily breaks under impact, failing to meet the requirements of frozen food packaging. Furthermore, the film is susceptible to holes or tears during transportation and storage, affecting packaging integrity. For packaging items with sharp edges, the film is also easily punctured, losing its barrier function and impacting the packaging's lifespan. Additionally, BOPP film is prone to scratches during transportation and use, reducing its optical performance and product display. Therefore, ensuring BOPP film possesses good abrasion resistance and mechanical properties is crucial for providing a superior user experience.

[0005] In conclusion, although BOPP film is widely used in the packaging field, it still has many shortcomings in many aspects. There is an urgent need to improve its overall performance by improving the manufacturing process in order to meet the higher requirements of packaging applications. Summary of the Invention

[0006] To address the aforementioned issues and further improve the abrasion resistance and mechanical properties of BOPP film, this application provides a renewable BOPP film, its preparation process, and its application.

[0007] In a first aspect, this application provides a renewable BOPP film, comprising an upper surface layer, a core layer, and a lower surface layer;

[0008] Both the upper and lower surface layers comprise the following components: anti-sticking masterbatch, homopolymer polypropylene;

[0009] The core layer comprises the following components: homopolymer polypropylene and recycled polypropylene material;

[0010] The anti-sticking masterbatch is obtained by mixing and granulating homopolymer polypropylene, maleic anhydride grafted polypropylene, and composite fibers.

[0011] The composite fiber is composed of polyphenylene sulfide-nylon base fiber and silica and gel microspheres attached to the surface of the polyphenylene sulfide-nylon base fiber.

[0012] Furthermore, the method for preparing the composite fiber includes the following steps:

[0013] M1: Dissolve polyvinyl alcohol in an aqueous solution of phosphoric acid, add methacrylamide and organic acid, and carry out a cross-linking reaction. After the reaction is completed, dry the product and grind it to obtain gel microspheres.

[0014] M2: Disperse polyphenylene sulfide-nylon base fibers in a solvent, then add tetraethyl orthosilicate and γ-mercaptopropyltriethoxysilane, adjust the pH value with NaOH, add gel microspheres after reacting for a period of time, continue the reaction, wash and dry after the reaction is completed to obtain composite fibers.

[0015] Furthermore, the preparation method of the polyphenylene sulfide-nylon base fiber includes the following steps:

[0016] 1) Hydroxylated nylon and polyphenylene sulfide are mixed, dried, and then melt-spun to obtain nascent fibers;

[0017] 2) The nascent fibers are further stretched and heat-set to obtain polyphenylene sulfide-nylon base fibers.

[0018] Furthermore, the average length of the polyphenylene sulfide-nylon base fiber is 1-1.5 mm.

[0019] Furthermore, in step 1), the preparation method of hydroxylated nylon includes the following steps:

[0020] S1: Mix polyol and trimellitic anhydride and carry out esterification reaction under the action of catalyst. After the reaction is completed, add more polyol and then add p-toluenesulfonic acid to carry out chain extension reaction. After the reaction is completed, rotary evaporate to obtain hyperbranched molecules.

[0021] S2: Nylon 66 and hyperbranched molecules are mixed and melt-extruded to obtain hydroxylated nylon.

[0022] Furthermore, in step 1), the temperature of the melt spinning nozzle is 310-330℃, the spinning speed is 800-1200m / min, and the spinneret orifice diameter is 0.18-0.3mm.

[0023] Furthermore, in step 1), the mass ratio of hydroxylated nylon to polyphenylene sulfide is 1:(9-12).

[0024] Furthermore, in step S2, the mass ratio of nylon 66 to hyperbranched molecules is (20-30):1.

[0025] Furthermore, by weight, both the upper and lower surface layers comprise the following components: 2-5 parts of anti-sticking masterbatch and 95-100 parts of homopolymer polypropylene.

[0026] The core layer comprises the following components: 25-70 parts of homopolymer polypropylene and 30-70 parts of recycled polypropylene.

[0027] Secondly, this application provides a process for preparing a renewable BOPP film, comprising the following steps: using a three-layer co-extrusion casting technology, mixing the components of the upper surface layer, core layer and lower surface layer in proportion, extruding, casting to obtain a thick sheet; after the thick sheet is stretched longitudinally and laterally, it is then shaped, and finally trimmed and wound to obtain a renewable BOPP film.

[0028] Thirdly, this application provides an application of renewable BOPP film in the outer packaging film of daily necessities.

[0029] Compared with the prior art, this application has the following beneficial effects:

[0030] 1. The composite fibers form an interlaced "skeleton structure" in BOPP, which can effectively resist the puncture of sharp objects and improve the toughness and durability of the film. In addition, it has excellent heat resistance. After addition, it can increase the heat distortion temperature of BOPP film and reduce shrinkage or softening under high temperature environment.

[0031] 2. The mercapto-modified silica on the surface of the composite fiber reacts with maleic anhydride during the preparation of the anti-sticking masterbatch, which can improve the bonding force between the composite fiber and polypropylene. The dispersion of the composite fiber in the polypropylene matrix is ​​improved, forming a more uniform and stable stress dispersion structure, thereby improving the mechanical properties of the film. At the same time, the silica adheres to the surface of the composite fiber, which enhances the wear resistance of the fiber and further improves the anti-slip and wear resistance of the film.

[0032] 3. When hyperbranched molecules containing terminal hydroxyl groups are blended and melted with nylon, some of the terminal hydroxyl groups interact with the amide groups in the nylon, enhancing the bonding force between the hyperbranched molecules and the nylon. This allows the hyperbranched molecules to be dispersed more uniformly in the nylon. This also allows some terminal hydroxyl groups to remain on the nylon surface, combining with the hydroxyl groups on the silica surface, improving the bonding force between silica and the fiber, preventing silica from slipping off under friction, and maintaining the stability of the composite fiber's properties. Simultaneously, the addition of nylon further enhances the toughness of the composite fiber, which has a beneficial effect on the mechanical properties of the film.

[0033] 4. Gel microspheres form an elastic buffer structure on the fiber surface. When the plastic film is impacted by external force, the microparticles can absorb energy through their own deformation, thereby improving the impact toughness of the film. Some silica covers the surface of the gel microspheres, forming an outer shell that retains high hardness and can directly resist surface friction. The inner elastic core can absorb external force through elastic deformation, reducing the instantaneous stress on the outer shell, maintaining the anti-wear effect, and reducing the wear rate. Attached Figure Description

[0034] Figure 1 This is a scanning electron microscope image of the composite fiber of Example 1 of this application. Detailed Implementation

[0035] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0037] When using “including,” “having,” and “contains” as described herein, the intention is to cover non-exclusive inclusion, unless an explicit qualifying term such as “only,” “consisting of,” etc., is used, in which case another component may be added.

[0038] The terms "preferred," "more preferably," "better," and "even better" used in this application refer to embodiments of this application that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this application. That is, in this application, "preferred," "more preferably," "better," and "even better" are merely descriptions of implementations or embodiments with better effects, but do not constitute a limitation on the scope of protection of this application.

[0039] In this application, terms such as "further," "even more," and "particularly" are used for descriptive purposes and to indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0040] In this application, "at least one" means one or more, such as one, two, or more. "Multiple" or "several" means at least two, such as two, three, etc., and "multi-layered" means at least two layers, such as two layers, three layers, etc., unless otherwise explicitly specified. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise explicitly specified.

[0041] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0042] Unless otherwise specified, all steps of this application may be performed sequentially or randomly. For example, the method comprising steps (a) and (b) indicates that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc. Unless otherwise stated, singular terms may include plural forms and should not be construed as having a quantity of one.

[0043] In this application, "above" or "below" includes the number itself. For example, "below 1" includes 1.

[0044] In this application, room temperature refers to 0-40°C, including but not limited to 10-40°C, or further to 20-30°C.

[0045] Based on extensive experimental research, this application provides a renewable BOPP film, comprising an upper surface layer, a core layer, and a lower surface layer.

[0046] Both the upper and lower surface layers comprise the following components: anti-sticking masterbatch and homopolymer polypropylene;

[0047] The core layer comprises the following components: homopolymer polypropylene, recycled polypropylene, and antistatic masterbatch;

[0048] The anti-sticking masterbatch is obtained by mixing and granulating homopolymer polypropylene, maleic anhydride grafted polypropylene, and composite fibers.

[0049] The composite fiber is composed of polyphenylene sulfide-nylon base fiber and silica and gel microspheres attached to the surface of the polyphenylene sulfide-nylon base fiber.

[0050] In some embodiments of this application, the method for preparing the anti-sticking masterbatch includes the following steps: adding homopolymer polypropylene, maleic anhydride-grafted polypropylene, and composite fibers into a feeding system, and then blending and melting-granulating them through a twin-screw extruder to obtain the anti-sticking masterbatch.

[0051] In some embodiments of this application, the method for preparing the composite fiber includes the following steps:

[0052] M1: Dissolve polyvinyl alcohol in an aqueous solution of phosphoric acid, add methacrylamide and organic acid, and carry out a cross-linking reaction. After the reaction is completed, dry the product and grind it to obtain gel microspheres.

[0053] M2: Disperse polyphenylene sulfide-nylon base fibers in a solvent, then add tetraethyl orthosilicate and γ-mercaptopropyltriethoxysilane, adjust the pH value with NaOH, add gel microspheres after reacting for a period of time, continue the reaction, wash and dry after the reaction is completed to obtain composite fibers.

[0054] In some embodiments of this application, step M2, the preparation method of polyphenylene sulfide-nylon base fiber includes the following steps:

[0055] 1) Hydroxylated nylon and polyphenylene sulfide are mixed, dried, and then melt-spun to obtain nascent fibers;

[0056] 2) The nascent fibers are further stretched and heat-set to obtain polyphenylene sulfide-nylon base fibers.

[0057] In some embodiments of this application, in step 1), the mass ratio of hydroxylated nylon to polyphenylene sulfide is 1:(9-12).

[0058] In some specific embodiments of this application, the mass ratio of hydroxylated nylon to polyphenylene sulfide can be 1:(9-10), 1:(10-11), or 1:(11-12); typically, but not limitingly, it can be 1:9, 1:10, or 1:12.

[0059] In some embodiments of this application, in step 1), the temperature of the melt spinning nozzle is 310-330℃, the spinning speed is 800-1200m / min, and the spinneret orifice diameter is 0.18-0.3mm.

[0060] In some specific embodiments of this application, the nozzle temperature for melt spinning can be 310-315℃, 315-320℃, 320-325℃, or 325-330℃; typically, but not limitingly, it can be 310℃ or 315℃; the spinning speed can be 800-900m / min, 900-1000m / min, 1000-1100m / min, or 1100-1200m / min; typically, but not limitingly, it can be 1000m / min; the spinneret orifice diameter can be 0.18-0.2mm, 0.2-0.22mm, 0.22-0.24mm, 0.24-0.26mm, 0.26-0.28mm, or 0.28-0.3mm; typically, but not limitingly, it can be 0.2mm or 0.21mm.

[0061] In some embodiments of this application, step 1) of the preparation method of hydroxylated nylon includes the following steps:

[0062] S1: Mix polyol and trimellitic anhydride and carry out esterification reaction under the action of catalyst. After the reaction is completed, add more polyol and then add p-toluenesulfonic acid to carry out chain extension reaction. After the reaction is completed, rotary evaporate to obtain hyperbranched molecules.

[0063] S2: Nylon 66 and hyperbranched molecules are mixed and melt-extruded to obtain hydroxylated nylon.

[0064] In some embodiments of this application, in step S2, the mass ratio of nylon 66 to hyperbranched molecules is (20-30):1.

[0065] In some specific embodiments of this application, the mass ratio of nylon 66 to hyperbranched molecules can be (20-21):1, (21-22):1, (22-23):1, (23-24):1, (24-25):1, (25-26):1, (26-27):1, (27-28):1, (28-29):1, (29-30):1; typically, but not limitingly, it can be 20:1 or 25:1.

[0066] In some embodiments of this application, the upper and lower surface layers, by weight, each comprise the following components: 2-5 parts of anti-sticking masterbatch and 95-100 parts of homopolymer polypropylene.

[0067] The core layer comprises the following components: 25-70 parts of homopolymer polypropylene and 30-70 parts of recycled polypropylene.

[0068] The present application will be further illustrated by the following examples, but these examples do not limit the scope of the present application.

[0069] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in this application, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. All reagents or instruments whose manufacturers are not specified are conventional products that can be purchased commercially. In addition to the specific methods, equipment, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description in this application, any prior art methods, equipment, and materials similar to or equivalent to those described, used, or made by the methods, equipment, and materials in the embodiments of this application may be used to implement this application.

[0070] Example 1

[0071] The renewable BOPP film of this embodiment includes an upper surface layer, a core layer, and a lower surface layer. The upper and lower surface layers are each composed of the following components: 4g of anti-sticking masterbatch, 190g of homopolymer polypropylene, 0.2g of erucamide, and 0.15g of glyceryl monostearate. The core layer is composed of the following components: 50g of homopolymer polypropylene, 140g of recycled polypropylene, 8g of maleic anhydride-grafted polypropylene, and 0.1g of EP548s nucleating agent. The average thickness of the upper surface layer is 6.9μm, the average thickness of the lower surface layer is 7.04μm, and the average total thickness of the renewable BOPP film is 35.22μm.

[0072] The preparation method of polyphenylene sulfide-nylon base fiber in this embodiment is as follows:

[0073] 1) Take 13.6g of glycerol and 54g of trimellitic anhydride and put them into a 250mL three-necked flask. After mixing evenly, adjust the temperature to 160℃, add 1g of zinc sulfate under a nitrogen atmosphere, stir and react for 4h. Then adjust the temperature to 120℃, add 18.5g of glycerol, and then add 2g of p-toluenesulfonic acid. React for 3h. After the reaction is completed, rotary evaporate, filter, and centrifuge to obtain hyperbranched molecules.

[0074] 2) Weigh 200g of nylon 66 and 8g of hyperbranched molecules and add them to a high-speed mixer. Mix for 5 minutes at a speed of 800r / min. Add the mixed material to the hopper of a twin-screw extruder for melt extrusion. The die head temperature of the twin-screw extruder is 230℃. The strip material obtained by the twin-screw extruder is granulated by a pelletizer and dried to obtain hydroxylated nylon.

[0075] 3) Weigh 2g of hydroxylated nylon and 18g of polyphenylene sulfide and mix them. Dry them in a vacuum drying oven at 120℃ for 6 hours. After drying, melt spin spinning is performed at a temperature of 310℃ and a spinning speed of 1000m / min. The spinneret used has an orifice diameter of 0.2mm to obtain nascent fibers.

[0076] 4) The nascent fibers are further stretched and heat-set using a three-stage hot roller stretcher and a hot air circulating setter. During stretching, the temperature of the first roller is 110℃, the temperature of the second roller is 135℃, and the temperature of the third roller is 170℃. The stretching ratio is 3.5-4. The heat-setting temperature is 165℃. After cooling, the fibers are crushed to obtain polyphenylene sulfide-nylon base fibers with an average length of 1.5mm.

[0077] The method for preparing the composite fiber in this embodiment is as follows:

[0078] M1: Measure 150 mL of 42% (w / w) phosphoric acid aqueous solution and add it to a three-necked flask. Then add 15 g of polyvinyl alcohol, heat to 85 °C, stir for 3 h, then add 6 g of methacrylamide, 1.2 g of citric acid and 0.1 g of ammonium persulfate, react for 2 h, dry the product after the reaction, pulverize it, put it into a medium-stirred mill, add 70 g of deionized water, grind for 35 min, the grinding medium is zirconia beads with an average diameter of 0.6 mm, the amount of zirconia beads added is 75 g, the speed is 1100 rpm, filter, dry, and obtain gel microspheres.

[0079] M2: Weigh 10g of polyphenylene sulfide-nylon base fiber and place it in a beaker. Add 90g of ethanol and 100g of deionized water, and ultrasonically disperse it evenly. Then add 6.5g of tetraethyl orthosilicate and 0.15mL of γ-mercaptopropyltriethoxysilane. Adjust the pH value to 13 with NaOH. After reacting for 1h, add 1g of gel microspheres and continue reacting for 2.5h. After the reaction is completed, filter, wash, and dry to obtain composite fiber.

[0080] The preparation method of the anti-sticking masterbatch in this embodiment is as follows: 180g of homopolymer polypropylene and 10g of maleic anhydride-grafted polypropylene are placed in an electric heating drying oven and dried at 80°C for 5 hours. The dried material is then mixed with 10g of composite fiber and melt-blended extruded using a twin-screw extruder. The temperature settings of the twin-screw extruder are: Zone 1 155°C, Zone 2 165°C, Zone 3 175°C, Zone 4 185°C, Zone 5 195°C, Zone 6 190°C, Zone 7 185°C, and die head 185°C. The sample obtained by the twin-screw extruder is granulated using a pelletizer and dried to obtain the anti-sticking masterbatch.

[0081] The preparation process of the BOPP film in this embodiment is as follows: Each layer component is mixed evenly according to the ratio, melted using an extruder for each layer, and then co-extruded through a three-layer die. The melt extrusion temperature of the upper and lower surface layers is 220-245℃, and the melt extrusion temperature of the core layer is 235-255℃. The film is then cast into a thick sheet by a cooling roller at 10-15℃, preheated at 130℃, and stretched longitudinally by 4.5 times. The temperature is then adjusted to 160℃ for transverse stretching, with a transverse stretching ratio of 8. The film is then shaped at 150℃, and finally trimmed and wound up to obtain the recyclable BOPP film.

[0082] Example 2

[0083] The renewable BOPP film of this embodiment includes an upper surface layer, a core layer, and a lower surface layer. The upper and lower surface layers are each composed of the following components: 10g of anti-sticking masterbatch, 200g of homopolymer polypropylene, 0.3g of erucamide, and 0.2g of glyceryl monostearate. The core layer is composed of the following components: 140g of homopolymer polypropylene, 60g of recycled polypropylene, 4g of maleic anhydride-grafted polypropylene, and 0.15g of EP548s nucleating agent. The average thickness of the upper surface layer is 7.49μm, the average thickness of the lower surface layer is 8.03μm, and the average total thickness of the renewable BOPP film is 35.16μm.

[0084] The preparation method of polyphenylene sulfide-nylon base fiber in this embodiment is as follows:

[0085] 1) Take 14g of glycerol and 54g of trimellitic anhydride and put them into a 250mL three-necked flask. After mixing evenly, adjust the temperature to 160℃, add 1g of zinc sulfate under a nitrogen atmosphere, stir and react for 4h. Then adjust the temperature to 120℃, add 18g of glycerol, and then add 2g of p-toluenesulfonic acid. React for 3h. After the reaction is completed, rotary evaporate, filter, and centrifuge to obtain hyperbranched molecules.

[0086] 2) Weigh 200g of nylon 66 and 10g of hyperbranched molecules and add them to a high-speed mixer. Mix for 5 minutes at a speed of 800r / min. Add the mixed material to the hopper of a twin-screw extruder for melt extrusion. The die head temperature of the twin-screw extruder is 230℃. The strip material obtained by the twin-screw extruder is granulated by a pelletizer and dried to obtain hydroxylated nylon.

[0087] 3) Weigh 2g of hydroxylated nylon and 18g of polyphenylene sulfide and mix them. Dry them in a vacuum drying oven at 120℃ for 6 hours. After drying, melt spin them at a temperature of 315℃ and a spinning speed of 1000m / min. The spinneret used has an orifice diameter of 0.21mm to obtain nascent fibers.

[0088] 4) The nascent fibers are further stretched and heat-set using a three-stage hot roller stretcher and a hot air circulating setter. During stretching, the temperature of the first roller is 110℃, the temperature of the second roller is 135℃, and the temperature of the third roller is 170℃. The stretching ratio is 3.5-4. The heat-setting temperature is 165℃. After cooling, the fibers are crushed to obtain polyphenylene sulfide-nylon base fibers with an average length of 1mm.

[0089] The method for preparing the composite fiber in this embodiment is as follows:

[0090] M1: Measure 150 mL of 41.5% (w / w) phosphoric acid aqueous solution and add it to a three-necked flask. Then add 15 g of polyvinyl alcohol, heat to 85 °C, stir for 3 h, then add 6 g of methacrylamide, 1.2 g of citric acid and 0.1 g of ammonium persulfate, react for 2 h. After the reaction is complete, dry the product, pulverize it, put it into a medium-stirred mill, add 70 g of deionized water, and grind for 35 min. The grinding medium is zirconia beads with an average diameter of 0.6 mm, the amount of zirconia beads added is 75 g, the speed is 1000 rpm, filter, dry, and obtain gel microspheres.

[0091] M2: Weigh 10g of polyphenylene sulfide-nylon base fiber and place it in a beaker. Add 90g of ethanol and 100g of deionized water, and ultrasonically disperse it evenly. Then add 6.5g of tetraethyl orthosilicate and 0.15mL of γ-mercaptopropyltriethoxysilane. Adjust the pH value to 13 with NaOH. After reacting for 1 hour, add 1.2g of gel microspheres and continue reacting for 2.5 hours. After the reaction is completed, filter, wash, and dry to obtain composite fiber.

[0092] The preparation method of the anti-sticking masterbatch in this embodiment is as follows: 180g of homopolymer polypropylene and 10g of maleic anhydride-grafted polypropylene are placed in an electric heating drying oven and dried at 80°C for 5 hours. The dried material is then mixed with 8g of composite fiber and melt-blended extruded using a twin-screw extruder. The temperature settings of the twin-screw extruder are: Zone 1 155°C, Zone 2 165°C, Zone 3 175°C, Zone 4 185°C, Zone 5 195°C, Zone 6 190°C, Zone 7 185°C, and die head 185°C. The sample obtained by the twin-screw extruder is granulated using a pelletizer and dried to obtain the anti-sticking masterbatch.

[0093] The preparation process of the BOPP film in this embodiment is as follows: Each layer component is mixed evenly according to the ratio, melted using an extruder for each layer, and then co-extruded through a three-layer die. The melt extrusion temperature of the upper and lower surface layers is 220-245℃, and the melt extrusion temperature of the core layer is 235-255℃. The film is then cast into a 1mm thick sheet by a cooling roller at 10-15℃. After preheating at 130℃, it is stretched longitudinally by 4.6 times. The temperature is then adjusted to 160℃ for transverse stretching, with a transverse stretching ratio of 8.5. The film is then shaped at 150℃, and finally trimmed and wound up to obtain the recyclable BOPP film.

[0094] Example 3

[0095] The renewable BOPP film of this embodiment includes an upper surface layer, a core layer, and a lower surface layer. The upper and lower surface layers are each composed of the following components: 5g of anti-sticking masterbatch, 197g of homopolymer polypropylene, 0.3g of erucamide, and 0.2g of glyceryl monostearate. The core layer is composed of the following components: 100g of homopolymer polypropylene, 100g of recycled polypropylene, 7g of maleic anhydride-grafted polypropylene, and 0.15g of EP548s nucleating agent. The average thickness of the upper surface layer is 7.32μm, the average thickness of the lower surface layer is 7.19μm, and the average total thickness of the renewable BOPP film is 35.51μm.

[0096] The preparation method of polyphenylene sulfide-nylon base fiber in this embodiment is as follows:

[0097] 1) Take 13.6g of glycerol and 54g of trimellitic anhydride and put them into a 250mL three-necked flask. After mixing them evenly, adjust the temperature to 160℃, add 1g of zinc sulfate under a nitrogen atmosphere, stir and react for 4h. Then adjust the temperature to 120℃, add 20g of glycerol, and then add 2g of p-toluenesulfonic acid. React for 3h. After the reaction is completed, rotary evaporate, filter, and centrifuge to obtain hyperbranched molecules.

[0098] 2) Weigh 200g of nylon 66 and 7g of hyperbranched molecules and add them to a high-speed mixer. Mix for 5 minutes at a speed of 800r / min. Add the mixed material to the hopper of a twin-screw extruder for melt extrusion. The die head temperature of the twin-screw extruder is 230℃. Granulate the strip obtained by the twin-screw extruder through a pelletizer and dry it to obtain hydroxylated nylon.

[0099] 3) Weigh 3g of hydroxylated nylon and 18g of polyphenylene sulfide and mix them. Dry them in a vacuum drying oven at 120℃ for 6 hours. After drying, melt spin spinning is performed at a temperature of 310℃ and a spinning speed of 1000m / min. The spinneret used has an orifice diameter of 0.2mm to obtain nascent fibers.

[0100] 4) The nascent fibers are further stretched and heat-set using a three-stage hot roller stretcher and a hot air circulating setter. During stretching, the temperature of the first roller is 110℃, the temperature of the second roller is 135℃, and the temperature of the third roller is 170℃. The stretching ratio is 3.5-4. The heat-setting temperature is 165℃. After cooling, the fibers are crushed to obtain polyphenylene sulfide-nylon base fibers with an average length of 1mm.

[0101] The method for preparing the composite fiber in this embodiment is as follows:

[0102] M1: Measure 150 mL of 42% (w / w) phosphoric acid aqueous solution and add it to a three-necked flask. Then add 15 g of polyvinyl alcohol, heat to 90 °C, stir for 3 h, then add 7 g of methacrylamide, 1.2 g of citric acid and 0.1 g of ammonium persulfate, react for 2 h, dry the product after the reaction, pulverize it, put it into a medium-stirred mill, add 70 g of deionized water, grind for 40 min, the grinding medium is zirconia beads with an average diameter of 0.6 mm, the amount of zirconia beads added is 75 g, the speed is 1100 rpm, filter, dry, and obtain gel microspheres.

[0103] M2: Weigh 10g of polyphenylene sulfide-nylon base fiber and place it in a beaker. Add 90g of ethanol and 100g of deionized water, and ultrasonically disperse it evenly. Then add 6.5g of tetraethyl orthosilicate and 0.15mL of γ-mercaptopropyltriethoxysilane. Adjust the pH value to 13 with NaOH. After reacting for 1h, add 1g of gel microspheres and continue reacting for 2.5h. After the reaction is completed, filter, wash, and dry to obtain composite fiber.

[0104] The preparation method of the anti-sticking masterbatch in this embodiment is as follows: 180g of homopolymer polypropylene and 10g of maleic anhydride-grafted polypropylene are placed in an electric heating drying oven and dried at 80°C for 5 hours. The dried material is then mixed with 5g of composite fiber and melt-blended extruded using a twin-screw extruder. The temperature settings of the twin-screw extruder are: Zone 1 155°C, Zone 2 165°C, Zone 3 175°C, Zone 4 185°C, Zone 5 195°C, Zone 6 190°C, Zone 7 185°C, and die head 185°C. The sample obtained by the twin-screw extruder is granulated using a pelletizer and dried to obtain the anti-sticking masterbatch.

[0105] The preparation process of the BOPP film in this embodiment is as follows: Each layer component is mixed evenly according to the ratio, melted using an extruder for each layer, and then co-extruded through a three-layer die. The melt extrusion temperature of the upper and lower surface layers is 220-245℃, and the melt extrusion temperature of the core layer is 235-255℃. The film is then cast into a 1mm thick sheet by a cooling roller at 10-15℃. After preheating at 130℃, it is stretched longitudinally by 4.5 times. The temperature is then adjusted to 160℃ for transverse stretching, with a transverse stretching ratio of 8. The film is then shaped at 150℃, and finally trimmed and wound up to obtain the recyclable BOPP film.

[0106] Control group 1

[0107] The recyclable BOPP film in this control group consists of an upper layer, a core layer, and a lower layer. The upper and lower layers are composed of the following components: 4g of anti-sticking masterbatch, 190g of homopolymer polypropylene, 0.2g of erucamide, and 0.15g of glyceryl monostearate. The core layer is composed of the following components: 50g of homopolymer polypropylene, 140g of recycled polypropylene, 8g of maleic anhydride-grafted polypropylene, and 0.1g of EP548s nucleating agent. The average thickness of the upper layer is 7.08μm, the average thickness of the lower layer is 7.02μm, and the average total thickness of the recyclable BOPP film is 35.16μm.

[0108] The preparation method of the composite fiber in this control group is as follows: 10g of polyphenylene sulfide-nylon base fiber was weighed and placed in a beaker, 90g of ethanol and 100g of deionized water were added, and the mixture was ultrasonically dispersed evenly. Then, 6.5g of tetraethyl orthosilicate and 0.15mL of γ-mercaptopropyltriethoxysilane were added, and the pH value was adjusted to 13 with NaOH. The reaction was carried out for 3.5h. After the reaction was completed, the fiber was filtered, washed, and dried to obtain the composite fiber.

[0109] The other steps are the same as in Example 1.

[0110] Control group 2

[0111] The recyclable BOPP film in this control group consists of an upper layer, a core layer, and a lower layer. Both the upper and lower layers are composed of the following components: 4g anti-stick masterbatch, 190g homopolymer polypropylene, 0.2g erucamide, and 0.15g glyceryl monostearate. The core layer is composed of the following components: 50g homopolymer polypropylene, 140g recycled polypropylene, 8g maleic anhydride-grafted polypropylene, and 0.1g EP548s nucleating agent. The average thickness of the upper layer is 6.97μm, the average thickness of the lower layer is 6.97μm, and the average total thickness of the recyclable BOPP film is 35.31μm.

[0112] The preparation method of the polyphenylene sulfide fiber in this control group is as follows:

[0113] 1) Weigh 20g of polyphenylene sulfide and dry it in a vacuum drying oven at 120℃ for 6h. After drying, melt spinning is performed at a temperature of 310℃ and a spinning speed of 1000m / min. The spinneret has an orifice diameter of 0.2mm to obtain nascent fibers.

[0114] 2) The nascent fibers are further stretched and heat-set using a three-stage hot roller stretcher and a hot air circulating setter. During stretching, the temperature of the first roller is 110℃, the temperature of the second roller is 135℃, and the temperature of the third roller is 170℃. The stretching ratio is 3.5-4. The heat-setting temperature is 165℃. After cooling, the fibers are crushed to obtain polyphenylene sulfide fibers with an average length of 1.5mm.

[0115] The preparation method of the composite fiber in this embodiment is as follows: Weigh 10g of polyphenylene sulfide fiber and put it into a beaker, add 90g of ethanol and 100g of deionized water, and disperse it evenly by ultrasonication. Then add 6.5g of tetraethyl orthosilicate and 0.15mL of γ-mercaptopropyltriethoxysilane, adjust the pH value to 13 with NaOH, react for 3.5h, filter, wash, and dry to obtain the composite fiber.

[0116] The other steps are the same as in Example 1.

[0117] Performance testing

[0118] 1. Various performance tests were conducted on the renewable BOPP films of Examples 1-3 and Control Groups 1-2. The test methods and data are shown in Table 1.

[0119] 2. The composite fibers prepared in Example 1 were observed using a scanning electron microscope, and the obtained images are as follows: Figure 1 As shown.

[0120] Table 1 Performance Test Methods and Data

[0121]

[0122] Analysis of Examples 1-3 and Control Groups 1-2, combined with Table 1, shows that the addition of composite fibers doped with hydroxylated nylon and deposited with silica and gel microspheres during the preparation of renewable BOPP films has a good effect on improving the mechanical properties and abrasion resistance of renewable BOPP films. The composite fibers prepared in the examples have good compatibility and bonding with the film matrix, which not only improves the mechanical properties of the film, but also makes the film have good dimensional stability.

[0123] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A renewable BOPP film, characterized in that: The upper surface layer, the core layer and the lower surface layer are included. The upper surface layer and the lower surface layer both include the following components: anti-sticking masterbatch, homopolymer polypropylene; The core layer includes the following components: homopolymer polypropylene, recycled polypropylene; The anti-sticking masterbatch is obtained by mixing homopolymer polypropylene, maleic anhydride grafted polypropylene and composite fibers and granulating; The composite fiber is composed of polyphenylene sulfide-nylon base fiber and silica and gel microspheres attached to the surface of the polyphenylene sulfide-nylon base fiber; The preparation method of the composite fiber includes the following steps: M1: polyvinyl alcohol is dissolved in phosphoric acid aqueous solution, methyl acrylamide and organic acid are added, crosslinking reaction is carried out, the product is dried after the reaction is completed, and grinding is carried out, to obtain gel microspheres; M2: polyphenylene sulfide-nylon base fiber is dispersed in a solvent, then tetraethyl orthosilicate and γ-mercaptopropyl triethoxysilane are added, the pH value is adjusted by NaOH, the reaction is continued for a period of time after the gel microspheres are added, and then the reaction is completed, followed by washing and drying, to obtain the composite fiber; The preparation method of the polyphenylene sulfide-nylon base fiber includes the following steps: 1) hydroxylated nylon and polyphenylene sulfide are mixed, and after drying, melt spinning is carried out to obtain primary fibers; 2) the primary fibers are continuously drawn and heat set to obtain polyphenylene sulfide-nylon base fiber; In step 1), the preparation method of the hydroxylated nylon includes the following steps: S1: polyol and trimellitic anhydride are mixed, esterification reaction is carried out under the action of a catalyst, after the reaction is completed, polyol is added again, then p-toluenesulfonic acid is added for chain extension reaction, and after the reaction is completed, rotary evaporation is carried out to obtain hyperbranched molecules; S2: nylon 66 and hyperbranched molecules are mixed and melt extruded to obtain hydroxylated nylon.

2. A renewable BOPP film as claimed in claim 1, wherein: In step 1), the nozzle temperature of melt spinning is 310-330 ℃, the spinning speed is 800-1200 m / min, and the spinneret hole diameter is 0.18-0.3 mm.

3. A renewable BOPP film as claimed in claim 1, wherein: In step 1), the mass ratio of hydroxylated nylon to polyphenylene sulfide is 1:(9-12).

4. A renewable BOPP film as claimed in claim 1, wherein: In step S2, the mass ratio of nylon 66 to hyperbranched molecules is (20-30):

1.

5. A renewable BOPP film as claimed in claim 1, wherein: The upper surface layer and the lower surface layer both include the following components: anti-sticking masterbatch 2-5 parts, homopolymer polypropylene 95-100 parts, by weight; The core layer includes the following components: homopolymer polypropylene 25-70 parts, recycled polypropylene 30-70 parts.

6. A process for the production of the renewable BOPP film as claimed in claim 1, characterized in that: The following steps are included: using three-layer co-extrusion casting technology, the components of the upper surface layer, the core layer and the lower surface layer are mixed in proportion, extruded, cast into a thick sheet, the thick sheet is subjected to longitudinal stretching and transverse stretching, then is subjected to setting treatment, and finally is subjected to edge cutting and winding treatment, to obtain the renewable BOPP film.

7. Use of a renewable BOPP film, characterized in that: The renewable BOPP film as claimed in any one of claims 1-6 is used as a daily necessity outer packaging film.

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