Degradable bio-based composite plastic cosmetic bottle and preparation method thereof

Abstract

The invention discloses a degradable bio-based composite plastic cosmetic bottle and a preparation method of the degradable bio-based composite plastic cosmetic bottle, and belongs to the technical field of high polymer materials and cosmetic packaging. The bio-based composite material is prepared from the following components in parts by weight: 40 to 60 parts of polylactic acid, 10 to 25 parts of modified plant fiber, 5 to 15 parts of supported nano calcium carbonate, 5 to 15 parts of bio-based elastomer and 2 to 5 parts of compatilizer. A bionic latticed structure is constructed on the surface of the inner wall of the bottle body, and a bacteriostatic functional layer loaded with natural plant extracts is formed on the surface of the bionic latticed structure in situ. Through the material-structure-process three-in-one collaborative innovative design, the obtained cosmetic bottle is high in bio-based content, excellent in mechanical property and good in antibacterial effect, the preparation method is simple and efficient, and the green and environment-friendly requirements are met.

Description

Technical Field

[0001] This invention relates to the field of polymer materials and cosmetic packaging technology, and in particular to a biodegradable bio-based composite plastic cosmetic bottle and its preparation method. Background Technology

[0002] Currently, with increasing global emphasis on environmental protection and sustainable development, the cosmetics industry is accelerating its transformation towards green, low-carbon, and recyclable methods. Traditional cosmetic packaging often uses glass or non-degradable plastics such as PE, PP, and PET, which are difficult to recycle or naturally degrade after disposal, causing serious "white pollution" and resource waste. Therefore, developing cosmetic packaging materials that combine excellent mechanical properties, high barrier properties, aesthetics, and complete biodegradability has become a research hotspot in the industry.

[0003] Polylactic acid (PLA), a biodegradable polyester derived from renewable resources (such as corn starch), possesses excellent biocompatibility, transparency, and mechanical strength, making it an ideal candidate material to replace traditional petroleum-based plastics. However, PLA's inherent brittleness, poor heat resistance, and slow crystallization rate severely limit its application in fields such as cosmetic packaging. To improve PLA's performance, existing technologies typically employ methods such as blending modification, fiber reinforcement, or nanocompositing. For example, Chinese invention patent application CN115895217A discloses a blow-molding-grade biodegradable material for cosmetic containers, comprising carbon nanotube-modified PLA and PBAT, but carbon nanotubes are costly and pose potential biosafety issues. Chinese invention patent application CN112694729A discloses a formulation for a biodegradable preform using plexiglass fiber-reinforced PLA, but the non-degradable nature of the glass fiber compromises the material's fully degradable properties. In addition, existing technologies mostly focus on modifying the materials themselves, with few reports on the integrated design of material formulation, product microstructure and molding process, especially in improving mechanical properties while endowing products with additional functions such as antibacterial and preservation, in order to meet the stringent requirements of high-end cosmetic packaging.

[0004] Therefore, how to collaboratively solve the problems of PLA-based materials such as high brittleness, poor interfacial bonding, and limited functionality through innovative formula design, ingenious microstructure, and precise molding process, and prepare a fully degradable cosmetic bottle with excellent comprehensive performance, controllable cost, and high added value, remains a technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0005] To address the technical bottlenecks in existing biodegradable bio-based plastics used in cosmetic packaging, such as high brittleness, insufficient toughness, poor interfacial compatibility, limited functionality, and difficulty in simultaneously achieving high strength and high degradation performance, this invention provides a biodegradable bio-based composite plastic cosmetic bottle and its preparation method. This invention aims to produce a fully biodegradable cosmetic bottle with high bio-based content, excellent mechanical properties (high strength and high toughness), antibacterial and preservation functions, and high molding precision through a synergistic innovative design integrating materials, structure, and process.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a biodegradable bio-based composite plastic cosmetic bottle, comprising a bottle body and an antibacterial functional layer attached to the inner wall of the bottle body;

[0008] The bottle body is obtained by injection molding of bio-based composite material, which includes the following components by weight: 40-60 parts of polylactic acid (PLA), 10-25 parts of modified plant fiber, 5-15 parts of supported nano-calcium carbonate, 5-15 parts of bio-based elastomer and 2-5 parts of compatibilizer.

[0009] The inner wall surface of the bottle body is constructed with a biomimetic grid structure;

[0010] The supported nano-calcium carbonate is nano-calcium carbonate loaded with natural plant extracts, and the antibacterial functional layer is formed by supported nano-calcium carbonate on the surface of the biomimetic mesh structure.

[0011] In some specific technical solutions of this invention, the modified plant fiber is microcrystalline cellulose or bamboo fiber surface-modified with a silane coupling agent, with an average aspect ratio of (10~20):1. By surface-modifying these plant fibers, such as microcrystalline cellulose or bamboo fiber, their interfacial compatibility with the polylactic acid (PLA) matrix can be significantly improved, preventing fiber agglomeration and thereby enhancing the tensile strength and impact toughness of the bio-based composite material.

[0012] In some specific technical solutions of this invention, the average particle size of the nano-calcium carbonate is 50-80 nm, serving as a loading carrier for natural plant extracts. The natural plant extracts are tea polyphenols or artemisia oil, loaded in the pores or on the surface of the nano-calcium carbonate, with a loading amount accounting for 5%-15% of the mass of the nano-calcium carbonate. Nano-calcium carbonate not only serves as a reinforcing filler, but its nanoscale size and porous characteristics also make it an ideal carrier for loading natural plant extracts, protecting heat-sensitive plant extracts from damage during subsequent high-temperature processing and achieving long-lasting sustained release.

[0013] In some specific technical solutions of the present invention, the bio-based elastomer is polybutylene adipate / terephthalate (PBAT) or polybutylene succinate (PBS), both of which are fully biodegradable materials with good compatibility with polylactic acid (PLA). They can form uniform elastomer microparticles in the polylactic acid (PLA) matrix, inducing shear yielding and creasing, thereby absorbing a large amount of impact energy and effectively improving the brittleness of polylactic acid.

[0014] In some specific technical solutions of the present invention, the compatibilizer is polylactic acid grafted glycidyl methacrylate (PLA-g-GMA) or an epoxy functionalized chain extender. Its epoxy groups can react with the hydroxyl groups on the surface of plant fibers and the terminal carboxyl / terminal hydroxyl groups of polylactic acid to form chemical bonds, thereby further improving the compatibility and stability of the multiphase system.

[0015] In some specific technical solutions of the present invention, the biomimetic mesh structure is composed of grooves distributed in a mesh pattern with a depth of 0.1~0.3mm and a width of 0.2~0.5mm.

[0016] Secondly, the present invention provides a method for preparing a biodegradable bio-based composite plastic cosmetic bottle as described above, comprising the following steps:

[0017] (1) Preparation of supported nano-calcium carbonate: Natural plant extracts were dissolved in anhydrous ethanol, nano-calcium carbonate was added, ultrasonically dispersed and then stirred for adsorption, and the solvent was removed by drying to obtain supported nano-calcium carbonate.

[0018] (2) Surface modification of plant fibers: plant fibers are dispersed in an ethanol aqueous solution, a silane coupling agent is added, the pH value is adjusted to 4~5, and the reaction is carried out at 50~70℃ for 2~4h. After washing and drying, modified plant fibers are obtained.

[0019] (3) Blending and granulation of bio-based composite materials: The dried polylactic acid (PLA), bio-based elastomer, modified plant fiber obtained in step (2), supported nano-calcium carbonate obtained in step (1) and compatibilizer are mixed evenly according to the ratio, melt-blended, extruded, cooled and granulated by a twin-screw extruder to obtain bio-based composite material granules.

[0020] (4) Injection molding: The bio-based composite material granules obtained in step (3) are injected into the mold cavity with a biomimetic grid structure texture, and the three-stage injection molding process is used for molding. After cooling, the mold is opened to obtain the bottle body.

[0021] (5) In-situ formation of antibacterial functional layer: During the injection molding process, when the melt fills the mold cavity in step (4), the nano-calcium carbonate loaded with natural plant extracts migrates and accumulates to the inner wall of the bottle body under the action of shear force, and forms an antibacterial functional layer on the surface of the biomimetic grid structure after cooling.

[0022] In some specific technical solutions of the present invention, in step (1), the ultrasonic dispersion time is 15~30 min, and the adsorption conditions are stirring and adsorption at 30~50℃ for 2~6 h.

[0023] In some specific technical solutions of the present invention, in step (3), the processing temperature of the twin-screw extruder is 160~190℃ and the screw speed is 200~400rpm.

[0024] In some specific technical solutions of the present invention, step (4) specifically includes the following three-stage injection molding process:

[0025] First stage of mold filling: Injection temperature 170~180℃, injection pressure 80~90MPa, injection speed 60~70mm / s;

[0026] The second pressure holding stage: The pressure holding pressure is controlled by gradient, decreasing from 60MPa to 40MPa, the pressure holding speed is 20~30mm / s, and the pressure holding time is 5~8s;

[0027] The third cooling stage: the mold temperature is controlled at 30~40℃, and the cooling time is set to 8~12s.

[0028] In some preferred embodiments of the present invention, in step (4), during the injection molding process, in-mold gas backpressure technology is also employed, applying a reverse gas pressure of 0.3~0.8MPa to the mold cavity during the melt filling stage. By introducing in-mold gas backpressure technology during the injection molding filling stage and applying a reverse gas pressure of 0.3~0.8MPa to the closed mold cavity, air in the microstructure area can be expelled before the melt front reaches it, and a back pressure is provided to prevent high-speed melt from entraining gas and forming cavities or scorch marks. This ensures that the melt can smoothly and completely fill each micro-grid, thus assisting in the accurate replication of the microstructure. This is crucial for the molding of high-precision microstructures.

[0029] Compared with the prior art, the present invention provides a biodegradable bio-based composite plastic cosmetic bottle and its preparation method, which has the following beneficial effects:

[0030] 1. Innovative Material Formulation Design: This invention abandons the approach of single modification and constructs a quaternary composite system of "PLA / modified plant fiber / supported nano-calcium carbonate / bio-based elastomer". By modifying the plant fiber with a silane coupling agent, the interfacial compatibility problem between the hydrophilic fiber and the hydrophobic PLA is solved, achieving efficient reinforcement. The introduction of the bio-based elastomer forms an "island" structure within the PLA matrix, significantly absorbing impact energy and achieving high toughness. Utilizing the porous properties of nano-calcium carbonate, it not only serves as a reinforcing filler and PLA nucleating agent but also as a "protective chamber" and "slow-release reservoir" for natural antibacterial agents, exerting protective and slow-release effects to achieve long-term effective antibacterial function. These four components synergistically achieve a composite material with high strength (tensile strength ≥ 50 MPa) and high toughness (notched impact strength ≥ 15 kJ / m²). 2 With its excellent comprehensive properties of high heat resistance (heat distortion temperature ≥80℃), it fully meets the requirements for use in cosmetic packaging.

[0031] 2. Integrated Innovation of Structure and Process: This invention features a biomimetic grid structure on the inner wall of the bottle. Based on the characteristics of this structure and the rheological properties of the material, a matching three-stage injection molding process of "temperature-pressure-speed" was developed. In particular, gradient pressure control ensures the accurate replication of the biomimetic grid structure, eliminating defects such as bubbles and shrinkage marks, achieving a yield rate of 99.5%. This structure not only reduces the bottle weight by 15-20% while increasing impact strength by more than 30%, solving the problem of high brittleness in biodegradable materials, but also, due to its increased inner wall surface area, facilitates the adhesion and formation of the subsequent antibacterial functional layer, thereby enhancing the surface gloss and mechanical properties of the bottle. The deep coupling of the biomimetic grid structure design with the molding process is one of the core creative innovations of this invention.

[0032] 3. The functional layer adopts an in-situ formation mechanism: This invention cleverly utilizes the fluid dynamics phenomena during the injection molding process, and through material formulation design (supported nano-calcium carbonate) and process parameter control, achieves the in-situ spontaneous formation of the antibacterial functional layer. This mechanism avoids the problems of complex procedures, increased costs, poor adhesion, and solvent contamination caused by traditional coating processes. The formed antibacterial layer has a significant antibacterial effect on cosmetic contents (antibacterial rate against Escherichia coli ≥95%), and can effectively extend the shelf life of the contents.

[0033] 4. Green and Environmentally Friendly with High Added Value: All raw materials used in this invention are bio-based or biodegradable, with a bio-based content of over 70%. The finished product is completely biodegradable after disposal, complying with "dual carbon" targets and international environmental regulations such as the EU Packaging Regulation (EPR). Furthermore, through a three-pronged innovation integrating materials, structure, and process, the product possesses high-value-added functional characteristics, meeting the demands of high-end cosmetic brands for sustainable, high-performance, and functional packaging. This results in broad market application prospects and significant economic benefits. Detailed Implementation

[0034] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] A biodegradable bio-based composite plastic cosmetic bottle includes a bottle body and an antibacterial functional layer attached to the inner wall of the bottle body. The bottle body is obtained by injection molding of a bio-based composite material, which includes the following components by weight: 40-60 parts of polylactic acid (PLA), 10-25 parts of modified plant fiber, 5-15 parts of supported nano-calcium carbonate, 5-15 parts of bio-based elastomer, and 2-5 parts of compatibilizer. The inner wall surface of the bottle body is constructed with a biomimetic mesh structure. The supported nano-calcium carbonate is nano-calcium carbonate loaded with natural plant extracts, and the antibacterial functional layer is formed by supported nano-calcium carbonate on the surface of the biomimetic mesh structure.

[0036] The modified plant fiber is microcrystalline cellulose or bamboo fiber surface-modified with a silane coupling agent, with an average aspect ratio of (10~20):1. The average particle size of the nano-calcium carbonate is 50~80nm. The natural plant extract is tea polyphenols or artemisia oil, loaded in the pores or on the surface of the nano-calcium carbonate, accounting for 5%~15% of the mass of the nano-calcium carbonate. The bio-based elastomer is polybutylene adipate / terephthalate (PBAT) or polybutylene succinate (PBS). The compatibilizer is polylactic acid grafted glycidyl methacrylate (PLA-g-GMA) or epoxy functionalized chain extender. The biomimetic mesh structure consists of grooves distributed in a mesh pattern with a depth of 0.1~0.3mm and a width of 0.2~0.5mm.

[0037] Furthermore, the preparation method of this biodegradable bio-based composite plastic cosmetic bottle includes the following steps:

[0038] (1) Preparation of supported nano-calcium carbonate: Natural plant extracts were dissolved in anhydrous ethanol to prepare a solution with a mass fraction of 10%~20%; nano-calcium carbonate (average particle size 50~80nm) was added, and the mixture was ultrasonically dispersed for 15~30min, then stirred and adsorbed at 30~50℃ for 2~6h; then the solvent was removed by vacuum drying at 40~60℃ to obtain supported nano-calcium carbonate. The purpose of this step is to adsorb and fix the heat-sensitive plant extracts onto the pores or surface of nano-calcium carbonate, and to utilize the protective effect of the inorganic carrier to prevent volatilization or decomposition during subsequent high-temperature extrusion and injection molding, which is the key to achieving long-lasting antibacterial function.

[0039] (2) Surface modification of plant fibers: Plant fibers (such as microcrystalline cellulose and bamboo fiber) are dispersed in a 70% (v / v) aqueous ethanol solution, and 1% to 3% (w / v) of silane coupling agent (such as KH550 or KH560) is added. The pH is adjusted to 4 to 5 with acetic acid, the temperature is raised to 50 to 70°C, and the reaction is stirred for 2 to 4 hours. After the reaction is completed, the mixture is filtered, washed 2 to 3 times with anhydrous ethanol, and dried under vacuum at 60 to 80°C to constant weight to obtain modified plant fibers. By treating with silane coupling agents, organic functional groups that can physically entangle or chemically react with polylactic acid (PLA) matrix are introduced on the surface of plant fibers, thereby greatly improving the interfacial bonding force between the fiber and the matrix, which is the basis for improving the mechanical strength of composite materials.

[0040] (3) Blending and granulation of bio-based composite materials: Polylactic acid (PLA), bio-based elastomer (such as PBAT), modified plant fiber obtained in step (2), supported nano-calcium carbonate obtained in step (1), and compatibilizer are mixed in a high-speed mixer for 3-5 minutes according to the formula ratio; then the mixture is added to a twin-screw extruder for melt blending, extrusion, cooling, and pelletizing to obtain bio-based composite material granules. The twin-screw extruder has an aspect ratio of 40:1, a processing temperature of 160-190℃ (gradually increasing from the feed port to the die head), and a screw speed of 200-400 rpm. This process achieves uniform dispersion of multiple components and, through reactive extrusion, enables the compatibilizer to compatibilize the interfaces of each phase in situ, providing a stable raw material for subsequent injection molding.

[0041] (4) Injection Molding: The bio-based composite material granules obtained in step (3) are injected into a mold cavity with a biomimetic mesh-like texture. A three-stage injection molding process is used for molding. After cooling, the mold is opened to obtain the bottle body. The mold cavity surface is mirror-polished, and a biomimetic mesh-like texture (such as a hexagonal honeycomb) with a depth of 0.1~0.3mm and a width of 0.2~0.5mm is processed at positions corresponding to the inner wall of the bottle body using laser engraving or etching technology. The specific process of the three-stage injection molding includes:

[0042] The first stage of mold filling: injection temperature 170~180℃, injection pressure 80~90MPa, injection speed 60~70mm / s. This stage aims to quickly fill the main part of the mold cavity to prevent the melt from cooling too early.

[0043] The second stage of pressure holding: The pressure holding is controlled by gradient, gradually decreasing from 60MPa to 40MPa, with a pressure holding speed of 20~30mm / s and a pressure holding time of 5~8s. This stage is the core of the biomimetic mesh structure forming. Under continuous pressure, the melt is precisely pressed into the micro-mesh texture on the surface of the mold and fills the volume gap caused by the cooling and shrinkage of the melt, ensuring the complete replication of the microstructure.

[0044] The third cooling stage: The mold temperature is controlled at 30~40℃ and the cooling time is 8~12s. The rapid cooling in this stage helps to "freeze" the microstructure shape and the crystal morphology of PLA, prevent the product from shrinking and deforming, and improve dimensional stability.

[0045] (5) In-situ formation of antibacterial functional layer: During the injection molding process, when the melt fills the mold cavity in step (4), the nano-calcium carbonate loaded with natural plant extracts migrates and accumulates to the inner wall of the bottle body under the action of shear force (this process is controlled by the holding pressure and holding time of the second stage of injection molding), and after cooling, an antibacterial functional layer is formed on the surface of the biomimetic grid structure.

[0046] In this invention, the antibacterial functional layer is not formed through a post-coating process, but rather spontaneously formed in situ during the injection molding process. Specifically, in the high-pressure injection and holding stages of step (4), a velocity gradient and shear stress field exist as the melt flows within the mold cavity. Due to the difference in fluidity and density between the nanoscale supported calcium carbonate and the polymer melt, they migrate under shear force, tending to accumulate near the melt front and mold wall where the shear rate is highest. When the melt contacts the mold wall (30-40°C) at a lower temperature, the surface layer rich in supported calcium carbonate rapidly solidifies, thus forming an antibacterial functional layer rich in natural plant extracts in situ on the inner wall surface of the bottle body, especially on the surface of the biomimetic mesh structure with a large specific surface area. By controlling the holding pressure and time in the second holding stage, the degree of migration and accumulation of calcium carbonate can be effectively controlled, thereby controlling the thickness and uniformity of the antibacterial layer. This method requires no additional coating process, is simple, and the functional layer is firmly bonded to the substrate and will not detach.

[0047] The present invention will be further described in detail below through detailed embodiments.

[0048] Unless otherwise specified, the experimental methods used in the examples and comparative examples are all conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0049] The source information of the raw materials used in the embodiments and comparative examples of this invention is as follows:

[0050] Polylactic acid (PLA), 4032D, NatureWorks, USA;

[0051] Microcrystalline cellulose (MCC), with an average particle size of 20 μm and an aspect ratio of 15:1, is commercially available.

[0052] Bamboo fiber, mechanically ground and passed through a 200-mesh sieve, with an aspect ratio of 15:1, is commercially available.

[0053] Nano-calcium carbonate, average particle size 60nm, Shanxi Ruicheng Huana Nanomaterials Co., Ltd.

[0054] Polybutylene adipate / butylene terephthalate (PBAT), C1200, BASF GmbH, Germany;

[0055] Polylactic acid grafted with glycidyl methacrylate (PLA-g-GMA), grafting rate 1.2%, prepared in the laboratory;

[0056] Silane coupling agent, KH550, Nanjing Chuangshi Chemical Additives Co., Ltd.;

[0057] Tea polyphenols, food grade, content ≥98%, Wuxi Taiyang Lvbao Technology Co., Ltd.

[0058] Artemisia argyi essential oil, food grade, Jiangxi Hengcheng Natural Fragrance Oil Co., Ltd.

[0059] Example 1

[0060] This embodiment provides a biodegradable bio-based composite plastic cosmetic bottle, including a bottle body and an antibacterial functional layer attached to the inner wall of the bottle body. The bottle body is injection molded from a bio-based composite material, and the inner wall surface of the bottle body has a biomimetic mesh structure, which consists of grooves distributed in a grid pattern with a depth of 0.2 mm and a width of 0.3 mm. The antibacterial functional layer is formed on the surface of the biomimetic mesh structure using nano-calcium carbonate loaded with natural plant extracts.

[0061] The preparation method of this biodegradable bio-based composite plastic cosmetic bottle includes the following steps:

[0062] (1) Preparation of supported nano-calcium carbonate: Natural plant extract (tea polyphenols) was dissolved in anhydrous ethanol to prepare a solution with a mass fraction of 15%; nano-calcium carbonate (average particle size 60nm) was added, ultrasonically dispersed for 20min, and then stirred and adsorbed at 40℃ for 4h; then the solvent was removed by vacuum drying at 50℃ for 24h to obtain supported nano-calcium carbonate (tea polyphenol loading of 9%).

[0063] (2) Surface modification of plant fiber: Weigh 100g of plant fiber (microcrystalline cellulose with an average aspect ratio of 15:1), disperse it in 1000mL of 70% ethanol aqueous solution, add 2g of silane coupling agent (KH550), adjust the pH value to 4.5 with acetic acid, heat to 60℃, and stir for 3h. After the reaction is completed, filter, wash twice with anhydrous ethanol, and vacuum dry at 60℃ to constant weight to obtain modified plant fiber.

[0064] (3) Blending and granulation of bio-based composite materials: Weigh 50 parts of polylactic acid (PLA), 10 parts of bio-based elastomer (PBAT), 20 parts of modified plant fiber obtained in step (2), 15 parts of supported nano-calcium carbonate obtained in step (1), and 5 parts of compatibilizer (PLA-g-GMA), totaling 100 parts; mix all components in a high-speed mixer for 3 minutes. Then add the mixture to a twin-screw extruder (length-to-diameter ratio of 40:1) for melt blending, extrusion, cooling, and pelletizing to obtain bio-based composite material granules. The processing temperature of the twin-screw extruder is set sequentially from the feed port to the die head as follows: Zone 1: 160℃, Zone 2: 170℃, Zone 3: 180℃, Zone 4: 185℃, and Die head: 185℃, with a screw speed of 300 rpm.

[0065] (4) Injection molding: After drying the bio-based composite material granules obtained in step (3) at 80°C for 4 hours, they are injected into a mold cavity with a biomimetic mesh structure texture. The surface of the mold cavity is mirror polished, and a biomimetic mesh structure texture (specifically a hexagonal honeycomb structure) with a depth of 0.2 mm and a width of 0.3 mm is processed at the position corresponding to the inner wall of the bottle by laser engraving or etching technology.

[0066] The molding process adopts a three-stage injection molding process, which includes: the first stage of mold filling (injection temperature 175℃, injection pressure 85MPa, injection speed 65mm / s), the second stage of holding pressure (holding pressure gradually decreases linearly from 60MPa to 40MPa, holding speed 25mm / s, holding time 6s), and the third stage of cooling (mold temperature controlled at 35℃, cooling time 10s).

[0067] After cooling, the mold is opened to obtain the bottle body.

[0068] (5) In-situ formation of antibacterial functional layer: During the injection molding process, when the melt fills the mold cavity in step (4), the nano-calcium carbonate loaded with natural plant extracts migrates and accumulates to the inner wall of the bottle body under the action of shear force, and forms an antibacterial functional layer on the surface of the biomimetic grid structure after cooling.

[0069] Example 2

[0070] This embodiment provides a biodegradable bio-based composite plastic cosmetic bottle and its preparation method, which is basically the same as that in Example 1, except that the plant fiber is replaced by bamboo fiber instead of microcrystalline cellulose. The other conditions remain unchanged, so they will not be described again.

[0071] Example 3

[0072] This embodiment provides a biodegradable bio-based composite plastic cosmetic bottle and its preparation method, which is basically the same as that in Example 1, except that the natural plant extract loaded is replaced with mugwort essential oil instead of tea polyphenols. The loading of mugwort essential oil is 8%, and the other conditions remain unchanged, so they will not be described in detail.

[0073] Example 4

[0074] This embodiment provides a biodegradable bio-based composite plastic cosmetic bottle and its preparation method, which is basically the same as that in embodiment 1. The difference is that the second stage of the injection molding in step (4) uses a constant pressure of 50MPa instead of a gradient pressure reduction. The other conditions remain unchanged, so they will not be described again.

[0075] Example 5

[0076] This embodiment provides a biodegradable bio-based composite plastic cosmetic bottle and its preparation method, which is basically the same as that in embodiment 1. The difference is that in the injection molding process of step (4), the in-mold gas back pressure device is turned on at the same time during the first stage of mold filling, and nitrogen back pressure of 0.5MPa is applied to the mold cavity. The other conditions remain unchanged, so they will not be described again.

[0077] Comparative Example 1

[0078] This comparative example provides a cosmetic bottle and its preparation method, which is basically the same as Example 1. The difference is that step (2) is removed, that is, the plant fiber is not modified by silane coupling agent, and is directly used to obtain bio-based composite material granules by co-mixing and granulation in step (3). The other conditions remain unchanged, so they will not be described again.

[0079] Comparative Example 2

[0080] This comparative example provides a cosmetic bottle and its preparation method, which is basically the same as Example 1. The difference is that no bio-based elastomer is added to the bio-based composite material formulation. That is, the bio-based composite material granules in step (3) are changed to be composed of 60 parts of polylactic acid (PLA), 20 parts of modified plant fiber, 15 parts of supported nano calcium carbonate (tea polyphenol loading of 9%) and 5 parts of compatibilizer (PLA-g-GMA is selected). The other conditions remain unchanged, so they will not be described in detail.

[0081] Comparative Example 3

[0082] This comparative example provides a cosmetic bottle and its preparation method, which is basically the same as Example 1. The difference is that the inner wall of the mold cavity in step (4) is a smooth surface without biomimetic mesh texture, and the inner wall surface of the cosmetic bottle is a smooth surface. The other conditions remain unchanged, so they will not be described again.

[0083] Comparative Example 4

[0084] This comparative example provides a cosmetic bottle and its preparation method, which is prepared using existing technology (refer to the formulation of Example 2 in CN112694729A): 120 parts of polylactic acid, 20 parts of plexiglass fiber, 12 parts of nano-calcium carbonate, 10 parts of silane coupling agent, 8 parts of nano-silica, 18 parts of phosphate and 5 parts of active dispersant are weighed, mixed, extruded and granulated, and then injection molded into a bottle body in a common smooth mold; then, a layer of tea polyphenol solution is coated on the inner wall of the bottle body by impregnation, and an antibacterial layer is formed after drying.

[0085] The cosmetic bottles prepared in Examples 1-5 and Comparative Examples 1-4 were subjected to the following performance tests, and the test results are shown in Table 1 below. Specific performance test items included tensile strength, notched impact strength, bio-based content, antibacterial rate, and microstructure replication rate. Tensile strength was tested according to GB / T 1040.2-2006 standard; notched impact strength was tested according to GB / T 1843-2008 standard; bio-based content was tested according to ASTM D6866 standard; antibacterial rate was tested against Escherichia coli according to GB / T 31402-2015 standard; and the microstructure replication rate was determined by observing the microstructure of the inner wall grid of the bottle using a laser confocal microscope, measuring the actual molding depth and width, and comparing it to the mold design dimensions.

[0086] Table 1. Performance test results of each embodiment and comparative example

[0087] The results in Table 1 are analyzed as follows:

[0088] (1) As can be seen from the test results of Examples 1 to 3, the cosmetic bottles prepared by the present invention have excellent comprehensive performance, with tensile strength greater than 55 MPa and notched impact strength higher than 16 kJ / m. 2 It is far superior to ordinary PLA materials, achieving the goal of high strength and high toughness. At the same time, the antibacterial rate is above 96%, and the bio-based content is as high as 78%, proving that the technical solution of this invention can simultaneously meet the requirements of mechanical properties, functionality, and environmental protection.

[0089] (2) Comparing Example 1 and Comparative Example 1, in Comparative Example 1, the plant fibers were not modified. Due to the poor interfacial bonding between the fibers and the PLA matrix, the tensile strength and notched impact strength of the composite material were significantly reduced. This indicates that surface modification of plant fibers to improve interfacial compatibility is the key to achieving reinforcement and toughening.

[0090] (3) Comparing Example 1 and Comparative Example 2, Comparative Example 2 did not add bio-based elastomer. Although the tensile strength was slightly improved, the notched impact strength decreased sharply (7.5 kJ / m). 2The material exhibits typical brittle fracture. This indicates that the introduction of elastomers is crucial for absorbing impact energy and improving the toughness of PLA-based composites.

[0091] (4) Comparing Example 1 and Comparative Example 3, the inner wall of the bottle in Comparative Example 3 has a smooth surface and no biomimetic mesh structure. Its impact strength (12.8 kJ / m) is lower. 2 The efficiency was significantly lower than that of Example 1, which had a biomimetic mesh structure (16.8 kJ / m³). 2 This study verified the significant contribution of the biomimetic grid structure to improving the impact resistance of the bottle, achieving a balance between weight reduction and reinforcement.

[0092] (5) Comparing Example 1 and Example 4, Example 4 uses constant holding pressure, and the microstructure replication rate (88%) is lower than that of Example 1 (95%) which uses gradient holding pressure. This shows that gradient holding pressure can more effectively compensate for shrinkage and improve the molding accuracy of microstructure, thus also having a positive impact on its mechanical properties (the impact strength of Example 4 is slightly lower than that of Example 1).

[0093] (6) Comparing Example 1 and Example 5, Example 5 introduced in-mold gas back pressure technology, and the microstructure replication rate reached 99%, and the mechanical properties were also optimal, which proved the auxiliary effect of the optimized process on high-precision microstructure molding.

[0094] (7) Comparing Example 1 and Comparative Example 4, Comparative Example 4, prepared using existing technology (unmodified fibers, no elastomers, no biomimetic mesh structure, and post-coating process), has a significantly lower overall performance than the present invention. In particular, its post-coated antibacterial layer not only increases the number of steps but also has poor adhesion, resulting in antibacterial effect and durability that cannot be compared with the in-situ formed antibacterial layer of the present invention. Furthermore, the use of plexiglass fibers reduces the bio-based content and biodegradability of the material. This comparison fully demonstrates the superiority of the "material-structure-process" integrated technical solution of the present invention.

[0095] As can be seen, this invention, through ingenious material formulation design, unique microstructure construction, and precise molding process control, has successfully prepared a biodegradable bio-based composite plastic cosmetic bottle with excellent comprehensive performance and high added value, which has good industrial application prospects and significant economic value.

[0096] The above embodiments are merely illustrative of the concept and technical solution of the present invention and are not intended to limit the present invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

[0097] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A biodegradable bio-based composite plastic cosmetic bottle, characterized in that, Includes the bottle body and the antibacterial functional layer attached to the inner wall of the bottle body; The bottle body is obtained by injection molding of bio-based composite material, which includes the following components by weight: 40-60 parts of polylactic acid, 10-25 parts of modified plant fiber, 5-15 parts of supported nano-calcium carbonate, 5-15 parts of bio-based elastomer and 2-5 parts of compatibilizer. The inner wall surface of the bottle body is constructed with a biomimetic grid structure; The supported nano-calcium carbonate is nano-calcium carbonate loaded with natural plant extracts, and the antibacterial functional layer is formed by supported nano-calcium carbonate on the surface of the biomimetic mesh structure.

2. The biodegradable bio-based composite plastic cosmetic bottle according to claim 1, characterized in that, The modified plant fiber is microcrystalline cellulose or bamboo fiber that has been surface modified with a silane coupling agent, with an average aspect ratio of (10~20):

1.

3. The biodegradable bio-based composite plastic cosmetic bottle according to claim 1, characterized in that, The average particle size of the nano-calcium carbonate is 50~80nm; the natural plant extract is tea polyphenol or artemisia oil, which is loaded in the pores or on the surface of the nano-calcium carbonate, and the loading amount accounts for 5%~15% of the mass of the nano-calcium carbonate.

4. The biodegradable bio-based composite plastic cosmetic bottle according to claim 1, characterized in that, The bio-based elastomer is polybutylene adipate / terephthalate or polybutylene succinate; the compatibilizer is polylactic acid grafted glycidyl methacrylate or epoxy functionalized chain extender.

5. The biodegradable bio-based composite plastic cosmetic bottle according to claim 1, characterized in that, The biomimetic mesh structure is composed of grooves distributed in a mesh pattern with a depth of 0.1~0.3mm and a width of 0.2~0.5mm.

6. A method for preparing a biodegradable bio-based composite plastic cosmetic bottle as described in any one of claims 1 to 5, characterized in that, Includes the following steps: (1) Preparation of supported nano-calcium carbonate: Natural plant extracts were dissolved in anhydrous ethanol, nano-calcium carbonate was added, ultrasonically dispersed and then stirred for adsorption, and the solvent was removed by drying to obtain supported nano-calcium carbonate. (2) Surface modification of plant fibers: plant fibers are dispersed in an ethanol aqueous solution, a silane coupling agent is added, the pH value is adjusted to 4~5, and the reaction is carried out at 50~70℃ for 2~4h. After washing and drying, modified plant fibers are obtained. (3) Blending and granulation of bio-based composite materials: The dried polylactic acid, bio-based elastomer, modified plant fiber obtained in step (2), supported nano-calcium carbonate obtained in step (1) and compatibilizer are mixed evenly according to the ratio, melt-blended, extruded, cooled and granulated by a twin-screw extruder to obtain bio-based composite material granules. (4) Injection molding: The bio-based composite material granules obtained in step (3) are injected into the mold cavity with a biomimetic grid structure texture, and the three-stage injection molding process is used for molding. After cooling, the mold is opened to obtain the bottle body. (5) In-situ formation of antibacterial functional layer: During the injection molding process, when the melt fills the mold cavity in step (4), the nano-calcium carbonate loaded with natural plant extracts migrates and accumulates to the inner wall of the bottle body under the action of shear force, and forms an antibacterial functional layer on the surface of the biomimetic grid structure after cooling.

7. The method for preparing a biodegradable bio-based composite plastic cosmetic bottle according to claim 6, characterized in that, In step (1), the ultrasonic dispersion time is 15~30 min, and the adsorption conditions are stirring and adsorption at 30~50℃ for 2~6 h.

8. The method for preparing a biodegradable bio-based composite plastic cosmetic bottle according to claim 6, characterized in that, In step (3), the processing temperature of the twin-screw extruder is 160~190℃ and the screw speed is 200~400rpm.

9. The method for preparing a biodegradable bio-based composite plastic cosmetic bottle according to claim 6, characterized in that, In step (4), the three-stage injection molding process specifically includes: First stage of mold filling: Injection temperature 170~180℃, injection pressure 80~90MPa, injection speed 60~70mm / s; The second pressure holding stage: The pressure holding pressure is controlled by gradient, decreasing from 60MPa to 40MPa, the pressure holding speed is 20~30mm / s, and the pressure holding time is 5~8s; The third cooling stage: the mold temperature is controlled at 30~40℃, and the cooling time is 8~12s.

10. The method for preparing a biodegradable bio-based composite plastic cosmetic bottle according to claim 6, characterized in that, In step (4), during the injection molding process, in-mold gas back pressure technology is also used to apply a reverse gas pressure of 0.3~0.8MPa to the mold cavity during the melt filling stage.

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