High-toughness low-temperature-resistant PE material and reagent bottle thereof

Abstract

This invention provides a high-toughness, low-temperature resistant PE material and its reagent bottle, belonging to the field of polymer technology. It contains high-molecular-weight polyethylene, maleic anhydride-grafted low-molecular-weight polyethylene, a toughening agent, p-methylsalicylic acid amphiphilic block oligomer, hydrogenated rosin acid amphiphilic block oligomer, and an antioxidant. This invention achieves a breakthrough in the performance of polyethylene materials through multi-component synergy; the key lies in the simultaneous introduction of two functionally complementary amphiphilic block oligomers: one ensures efficient stress transfer between the matrix and the toughening agent, fully utilizing the toughening agent's potential; the other creates nanoscale energy dissipation centers within the matrix, inducing microplastic deformation. The two synergistically construct a three-dimensional toughening network. Ultimately, the material achieves impact toughness far exceeding that of conventional systems while maintaining high strength, solving the industry problem of balancing strength and toughness.

Description

Technical Field

[0001] This invention belongs to the field of polymer technology, and in particular relates to a high-toughness, low-temperature resistant PE material and its reagent bottle. Background Technology

[0002] Polyethylene (PE), as one of the world's largest-produced and most widely used thermoplastics, is a crucial pillar of the plastics industry due to its excellent comprehensive properties and processability. From a molecular structure perspective, PE is a macromolecular chain formed by the polymerization of ethylene monomers. Its main chain consists of repeating -CH2-CH2- units, and this simple linear structure endows the material with good flexibility and chemical stability. This molecular structure is the basis for PE's high toughness and excellent low-temperature resistance.

[0003] In the packaging industry, polyethylene (PE) materials hold a pivotal position due to their superior chemical stability, excellent mechanical properties, and reliable safety. This is particularly true in pharmaceutical packaging, where material requirements are extremely stringent, where PE applications are more extensive and diverse. The core objective of pharmaceutical packaging is to protect the stability, safety, and efficacy of drugs, and PE materials, with their unique performance advantages, effectively meet these requirements. PE materials not only possess good mechanical properties, including sufficient strength, elasticity, and impact resistance to ensure effective protection of drugs during transportation and storage, but also exhibit excellent chemical stability, showing good resistance to most chemical solvents and being less prone to reaction with acids, alkalis, and other chemicals. This allows them to effectively protect drugs from the influence of external chemicals. Furthermore, PE materials' excellent low-temperature resistance enables them to maintain performance stability in extremely cold environments, which is crucial for drugs that need to be stored under frozen conditions. Their excellent sealing properties and suitable permeability effectively prevent the intrusion of air, moisture, and bacteria, while also preventing drugs from becoming ineffective due to moisture.

[0004] However, PE materials also have some significant drawbacks in packaging applications. Their barrier properties are relatively poor, particularly their limited ability to block oxygen, water vapor, and odors, which restricts their application in the packaging of certain highly sensitive pharmaceuticals. Furthermore, PE materials have insufficient high-temperature resistance; the upper limit of the operating temperature for PE products is generally around 80°C, making them unable to withstand high-temperature sterilization. This limits the use of medical devices and pharmaceutical packaging requiring high-temperature sterilization. PE materials also have poor printability due to their low surface energy, requiring special surface treatments such as corona treatment to achieve good printing results. This increases the complexity of the process in some packaging applications that require high-quality printing.

[0005] In specific pharmaceutical packaging applications, PE materials function primarily through various means. Oral solid pharmaceutical bottles are commonly made of high-density polyethylene (HDPE). These bottles are typically white and opaque because colorants such as titanium dioxide are added during production to provide light protection for light-sensitive drugs. In pharmaceutical packaging films and bags, low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE), due to their flexibility, transparency, and good heat-sealing properties, are frequently used to make packaging films and inner bags. For example, the packaging of injectable powders may employ a multi-layered composite structure, where the inner and outer layers may contain multiple PE components. This design allows the packaging material to maintain excellent impact resistance and environmental stress cracking resistance even at extremely low temperatures. It is worth noting that although PE materials perform well in these applications, their inherent permeability issues still require attention, especially for drugs that are easily oxidized or sensitive to moisture. In such cases, they often need to be used in combination with other high-barrier materials.

[0006] With the continuous development of packaging technology, pharmaceutical PE packaging is also undergoing continuous improvement and innovation. The industry has significantly improved the overall barrier properties of packaging by combining PE with other high-barrier materials through multi-layer co-extrusion technology, better protecting drugs sensitive to oxygen or water vapor. To overcome the insufficient temperature resistance of PE materials, researchers have developed modified varieties such as cross-linked polyethylene, improving the material's thermal stability. Due to its comprehensive performance advantages, PE materials play an indispensable role in pharmaceutical packaging, from oral solid dosage bottles to cryogenic frozen drug packaging, from simple single-layer bags to complex composite film structures. PE materials are playing a crucial role in ensuring the safety, efficacy, and stability of drugs, while their inherent limitations are also driving continuous progress in material modification technology. Summary of the Invention

[0007] The first objective of this invention is to provide a PE material that has high toughness and low-temperature resistance; it contains the following components in parts by weight:

[0008] High molecular weight polyethylene, at least 70 parts

[0009] Maleic anhydride-grafted low molecular weight polyethylene, at least 8 parts

[0010] Toughening agent, at least 20 parts

[0011] p-Methylsalicylic acid amphiphilic block oligomer, at least 1 part

[0012] Hydrogenated rosin acid amphiphilic block oligomer, at least 1 part

[0013] Antioxidant, at least 0.5 parts;

[0014] The weight-average molecular weight of the high molecular weight polyethylene is at least 300K, and the molecular weight distribution is ≤2.5.

[0015] The maleic anhydride-grafted low molecular weight polyethylene has a maximum weight-average molecular weight of 120K and a molecular weight distribution of Đ≤2.5.

[0016] The p-methylsalicylic acid amphiphilic block oligomer is an oligomer with a flexible segment linked to two p-methylsalicylic acid residues.

[0017] The hydrogenated rosin acid amphiphilic block oligomer is an oligomer in which a flexible segment is linked to two hydrogenated rosin acid residues.

[0018] Preferably, the flexible segment is an aliphatic polyether segment; and the number average molecular weight is ≤2000.

[0019] More preferably, the aliphatic polyether segment is polyethylene glycol or polypropylene glycol.

[0020] Preferably, the maleic anhydride-grafted low molecular weight polyethylene is prepared by grafting maleic anhydride onto polyethylene, and its grafting rate is ≤1.5%.

[0021] Preferably, the p-methylsalicylic acid amphiphilic block oligomer is prepared by condensation reaction of p-methylsalicylic acid with flexible segments under catalytic conditions.

[0022] Preferably, the hydrogenated rosin acid amphiphilic block oligomer is prepared by condensation reaction of hydrogenated rosin acid with flexible segments under catalytic conditions.

[0023] The second objective of this invention is to provide a method for preparing the aforementioned PE material. The method involves feeding high molecular weight polyethylene, maleic anhydride-grafted low molecular weight polyethylene, a toughening agent, and an antioxidant into a screw extruder via a feeder. Then, p-methylsalicylic acid amphiphilic block oligomer and hydrogenated rosin acid amphiphilic block oligomer are precisely injected into the screw extruder through a liquid injection port in the melting section. The process is then carried out using the screw extruder for melt blending, extrusion, cooling, drying, and pelletizing; this yields the PE material.

[0024] A third object of the present invention is to provide the application of the aforementioned PE material in the preparation of packaging materials. More specifically, the packaging material is pharmaceutical packaging.

[0025] A fourth object of the present invention is to provide a reagent bottle made of the aforementioned PE material.

[0026] The PE material provided by this invention, through the construction of a novel multi-component, multi-level synergistic system, cleverly balances the contradictions between the material's strength, toughness, and processability, achieving significantly superior overall performance compared to conventional blends. Specific beneficial effects are as follows:

[0027] (1) While maintaining high strength and high modulus, this material exhibits extremely high impact toughness, overcoming the shortcomings of high-strength polyethylene, which is usually lacking in toughness. This effect stems from the ternary synergistic structure of "rigid skeleton-flexible network-interface bridging".

[0028] High molecular weight polyethylene (HMWPE) serves as the matrix and rigid framework of the material. Its high molecular weight and regular chain structure ensure that the material possesses high crystallinity, tensile strength, and modulus, making it the main load-bearing component. Its nonpolar long molecular chains can form stable entanglements with the methyl ends of the amphiphilic block oligomers of p-methylsalicylic acid, providing an "anchoring foundation" for the oligomers and ensuring that the interfacial transition layer can firmly adhere to the matrix surface.

[0029] Toughening agents (such as POE) are the main flexible phases, distributed in the PE matrix as dispersed phases. Their core role is to absorb and dissipate a large amount of energy when the material is subjected to impact, through large deformation, initiation of crazing, and shear banding, making them the main contributor to the material's high toughness.

[0030] Amphiphilic block oligomers of p-methylsalicylic acid act as interfacial compatibilizers, precisely anchoring at the phase interface between HMWPE and POE. The nonpolar methyl group at one end of the molecule is compatible with HMWPE, while the polar segment at the other end interacts with POE, forming a strong "bridge" that significantly improves interfacial adhesion. This ensures that stress can be effectively transferred from the rigid matrix to the flexible POE phase, fully stimulating the toughening potential of POE and preventing failure due to interfacial delamination.

[0031] (2) In addition to macroscopic toughening by POE, an additional energy dissipation mechanism is formed inside the material body, which further increases the upper limit of toughness and moderately enhances the heat resistance and dimensional stability of the material.

[0032] This effect is primarily achieved by hydrogenated rosin acid amphiphilic block oligomers; these oligomers possess large triphenanthrene rings that act as dispersed, robust "islands," entangled with surrounding flexible chains and PE chains to form numerous tiny "energy dissipation units." These units directly participate in energy absorption. When the material is impacted, the flexible chains surrounding these "islands" undergo significant stretching and slippage, absorbing enormous amounts of energy. Furthermore, they are uniformly dispersed within the amorphous region of PE, entangled with the PE molecular chains. Under stress, these rigid "nano-islands" induce numerous microcrates and plastic deformation in the surrounding matrix, causing the connected flexible chain segments to stretch and absorb energy, thus achieving highly efficient energy dissipation at the microscale.

[0033] In this system, maleic anhydride-grafted low molecular weight polyethylene (POE) plays a dual role as a compatibility promoter and a network node. Its maleic anhydride functional group (grafting rate ≤1.5%) is key: it can interact not only with the potentially polar groups in the two amphiphilic oligomers but also undergo possible chemical reactions with the POE molecular chains, thus forming a synergistic network centered on chemical-physical crosslinking points in the multi-component system. This network stabilizes the phase morphology and enhances the cohesive strength of the material.

[0034] (3) The present invention addresses the challenge of how to achieve its effect through interfacial bonding strength. To solve this problem, the present invention employs a combination of maleic anhydride-grafted low molecular weight polyethylene and p-methylsalicylic acid amphiphilic block oligomers:

[0035] Introducing polar maleic anhydride (-COOH) groups into polyethylene resolves the compatibility conflict between the non-polar nature of pure PE and the polar groups of toughening agents (such as POE) and amphiphilic oligomers, avoiding agglomeration and delamination caused by polarity differences between components. Simultaneously, its low molecular weight imparts excellent flowability to the substrate, allowing rapid diffusion to the interface between the PE matrix and the toughening agent / oligomer during processing. The low molecular weight segments can form "long-short chain entanglements" with high molecular weight PE chains, preserving the rigidity of high molecular weight PE while mitigating interfacial stress concentration through the flexibility of the low molecular weight chains, thus reducing the risk of brittle fracture at low temperatures.

[0036] The amphiphilic block oligomer of methyl salicylic acid has a molecular structure of "monoaromatic ring + methyl group", which gives it the advantage of "pre-compatibility design". The specific working process is as follows:

[0037] The nonpolar methyl end in its molecular chain can form a stable molecular entanglement with the nonpolar molecular chain of high molecular weight polyethylene, and at the same time, it works synergistically with the low molecular weight segments of maleic anhydride-grafted low molecular weight PE to ensure strong interfacial bonding between the oligomer and the PE matrix. The polar phenolic hydroxyl end in the molecular chain can form hydrogen bonds with the polar groups of the toughening agent (POE) and the maleic anhydride groups of maleic anhydride-grafted PE, forming a dense and continuous "interfacial transition layer" at the phase interface between the PE matrix and the toughening agent. When the material is subjected to external impact, this interfacial transition layer can act as an "energy transfer bridge" to smoothly transfer the impact energy from the PE matrix to the POE. The energy is fully dissipated by the elastic deformation of the POE, avoiding cracking caused by stress concentration at the interface.

[0038] One of the key innovations of this invention lies in the simultaneous use of p-methylsalicylic acid amphiphilic block oligomers and hydrogenated rosin acid amphiphilic block oligomers. These two substances are distinct yet complementary in terms of molecular structure, action site, and functional mechanism; their synergistic effect is the core of achieving improved material performance.

[0039] p-Methylsalicylic acid amphiphilic block oligomers have a terminal p-methylsalicylic acid residue with a single aromatic ring and a small molecular size. The methyl group in the structure provides excellent precompatibility with the nonpolar PE matrix. This molecule is designed to preferentially migrate and locate at the interface between the PE matrix and the POE toughening agent. Its function is similar to building a "molecular bridge" between two incompatible polymers, significantly reducing interfacial energy and strengthening interfacial adhesion through physical entanglement and van der Waals forces.

[0040] Hydrogenated rosin acid amphiphilic block oligomers have terminal hydrogenated rosin acid residues with a large triphenanthrene ring structure, exhibiting extremely high rigidity and volume. This structure itself serves as a robust nanoscale physical crosslinking point. The molecule tends to disperse uniformly within the amorphous regions of the PE matrix. Its large, rigid structure makes it difficult for it to fully integrate into the PE lattice, thus forming numerous nanoscale "energy dissipation cores" within the matrix.

[0041] p-Methylsalicylic acid amphiphilic block oligomers are primarily responsible for macroscopic energy transfer. They ensure that when the material is subjected to impact, energy from crack tips or stress concentrations can be smoothly transferred from the brittle PE matrix to the flexible POE phase, thereby inducing large deformation in the POE to absorb energy. Their core function is to "prevent the interface from becoming a weak point." Hydrogenated rosin acid amphiphilic block oligomers are primarily responsible for microscopic energy dissipation. They create countless tiny "plastic deformation zones" within the PE matrix. When the material is under stress, these rigid "islands" induce numerous crazes, shear bands, and localized yielding in the surrounding PE molecular chains, directly dissipating enormous amounts of energy through plastic deformation. Their core function is to "make the matrix itself tougher."

[0042] Without the amphiphilic block oligomer of p-methylsalicylic acid, the compatibility between PE and POE is poor, resulting in weak interfacial adhesion. Under impact, stress transfer efficiency is significantly reduced, leading to interfacial debonding between POE particles and the PE matrix, forming macroscopic cracks that propagate rapidly. The toughening potential of POE cannot be realized, and the material's impact toughness will heavily rely on the inherently brittle PE matrix, resulting in toughness far below expectations. Without the amphiphilic block oligomer of hydrogenated rosin acid, the material loses most of the microplastic deformation capability induced by its inherent rigid structure. Energy dissipation depends solely on the deformation of POE particles and limited matrix yielding, thus limiting the toughening efficiency.

[0043] Although the two amphiphilic block oligomers are structurally similar, their performance differs significantly due to the different structures of their rigid segments. These two mechanisms together constitute a multi-level, three-dimensional energy dissipation network from the interface to the bulk, and from the macroscopic to the microscopic. The p-methylsalicylic acid amphiphilic block oligomer ensures 100% utilization of the toughening agent's capabilities in POE, while the hydrogenated rosin acid amphiphilic block oligomer provides an additional toughening pathway within the PE phase—one that POE lacks—based on plastic deformation induced by rigid particles. The two complement each other, producing a synergistic toughening effect of "1+1>2".

[0044] In summary, this invention achieves a breakthrough in the performance of polyethylene materials through multi-component synergy. High molecular weight polyethylene (POE) forms a rigid framework providing high strength; the toughening agent, as a flexible phase, contributes core toughness. The key lies in the simultaneous introduction of two functionally complementary amphiphilic block oligomers: p-methylsalicylic acid amphiphilic block oligomers ensure efficient stress transfer between the matrix and the toughening agent, fully leveraging the potential of POE; hydrogenated rosin acid amphiphilic block oligomers create nanoscale energy dissipation centers within the matrix, inducing microplastic deformation. These two synergistically construct a three-dimensional toughening network. The addition of maleic anhydride-grafted low molecular weight polyethylene improves compatibility and processing, ultimately enabling the material to achieve impact toughness far exceeding that of conventional systems while maintaining high strength, solving the industry challenge of balancing strength and toughness. Detailed Implementation

[0045] The technical solutions in the embodiments 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.

[0046] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0047] In the description of this invention, the term "for example" is used to mean "used as an example, illustration, or description." Any embodiment described as "for example" in this invention is not necessarily to be construed as being more preferred or advantageous than other embodiments. The following description is provided to enable any person skilled in the art to make and use the invention. Details are set forth in the following description for purposes of explanation. It should be understood that those skilled in the art will recognize that the invention can be made without using these specific details. In other instances, well-known structures and processes will not be described in detail to avoid obscuring the description of the invention with unnecessary detail. Therefore, the invention is not intended to be limited to the embodiments shown, but is consistent with the broadest scope of the principles and features disclosed herein.

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

[0049] In this invention, unless otherwise specified, "%" represents a percentage by mass; the raw materials and reagents used are all commercially available products.

[0050] The raw materials used in this invention are as follows:

[0051] Polyolefin elastomers: Exxon POE (USA)

[0052] Polyethylene glycol: PEG-2000

[0053] Polypropylene glycol: PPG-2000

[0054] High molecular weight polyethylene (HMWPE) has a weight-average molecular weight of 320K and a molecular weight distribution of Đ of 2.3.

[0055] Medium molecular weight polyethylene; weight-average molecular weight is 200K, and molecular weight distribution is 2.2.

[0056] Low molecular weight polyethylene: mPE, with a weight-average molecular weight of 110K and a molecular weight distribution of Đ of 2.2;

[0057] Polyethylene wax: weight average molecular weight is 40K, and molecular weight distribution is 2.5;

[0058] The polyethylenes of this invention are all synthesized using metallocene catalysis.

[0059] Example 1: Preparation of p-methylsalicylic acid amphiphilic block oligomers

[0060] (1) Preparation of p-methylsalicylic acid-PEG oligomers

[0061] The melt polycondensation method is used to generate an ABA-type amphiphilic block oligomer with PEG as a flexible spacer chain and both ends of p-methylsalicylic acid by esterification reaction between the carboxyl group on the p-methylsalicylic acid molecule and the hydroxyl groups at both ends of polyethylene glycol (PEG-2000).

[0062] raw material:

[0063] Polyethylene glycol (PEG-2000)

[0064] The molar ratio of p-methylsalicylic acid to polyethylene glycol is 2.2 mol: 1 mol (10% excess p-methylsalicylic acid to ensure complete reaction of the hydroxyl groups at the PEG chain ends).

[0065] Esterification catalyst: p-toluenesulfonic acid (p-TSA), added at 1.0% of the mass of p-methylsalicylic acid.

[0066] Antioxidant: Tris(2,4-di-tert-butylphenyl) phosphite (Irganox 168), added at 0.2% of the total feed mass.

[0067] Preparation steps:

[0068] S1 Feeding and Dehydration: In a reactor equipped with a stirrer, water separator, and condenser, add PEG-2000, p-methylsalicylic acid, catalyst, and antioxidant. Under nitrogen protection, slowly heat to 120°C and maintain a vacuum (-0.095 MPa) for 30 minutes to remove trace amounts of moisture from the raw materials.

[0069] S2 Esterification Reaction: After removing the vacuum, the reaction system temperature is slowly raised to 160±5℃ under a continuous nitrogen atmosphere. At this temperature, the esterification reaction begins, and the byproduct water is separated using a water separator. The reaction continues for at least 4 hours, and the reaction progress is monitored by periodically measuring the acid value of the system.

[0070] S3 Endpoint Judgment and Post-processing: When the measured acid value drops to more than 95% of the theoretically calculated value (indicating that the carboxyl group reaction is basically complete), the reaction can be determined as the endpoint. Stop heating, pour the reaction product into deionized water while it is still hot, and stir vigorously. The product will solidify into a white waxy solid.

[0071] S4 Purification: The crude product was filtered and washed three times with hot deionized water to remove unreacted p-methylsalicylic acid, catalyst, and trace amounts of PEG. Finally, the product was vacuum dried at 50°C for 12 hours to obtain a pale yellow waxy solid, which is the p-methylsalicylic acid-PEG oligomer.

[0072] (2) Preparation of p-methylsalicylic acid-PPG oligomers

[0073] The melt polycondensation method was used to esterify the carboxyl group on the methylsalicylic acid molecule with the hydroxyl group at the chain end of PPG-2000. Since the hydroxyl group of PPG is a secondary hydroxyl group, its reactivity is much lower than that of the primary hydroxyl group of PEG, thus requiring a more efficient catalytic system and / or a longer reaction time.

[0074] raw material:

[0075] Polypropylene glycol (PPG-2000)

[0076] The molar ratio of p-methylsalicylic acid to polypropylene glycol is 2.5 mol: 1 mol (p-methylsalicylic acid in 25% excess).

[0077] Esterification catalyst: Butyltin oxide (DBTO), added at 1.5% of the mass of p-methylsalicylic acid.

[0078] Antioxidant: Tris(2,4-di-tert-butylphenyl) phosphite (Irganox 168), added at 0.3% of the total feed mass.

[0079] Preparation steps:

[0080] S1 Feeding and Dehydration: In a reactor equipped with a stirrer, water separator, and condenser, add PPG-2000, p-methylsalicylic acid, and antioxidant. Under nitrogen protection, slowly heat to 100°C and maintain a vacuum (-0.095MPa) for 60 minutes to remove trace amounts of moisture from the raw materials.

[0081] S2 esterification reaction: Remove the vacuum and add the catalyst under a continuous nitrogen atmosphere; slowly raise the temperature of the reaction system to 170±5℃. At this temperature, the esterification reaction begins, and the byproduct water is separated by a water separator. The reaction continues for at least 6 hours, and the reaction progress is monitored by periodically measuring the acid value of the system.

[0082] S3 Endpoint Judgment and Post-processing: When the measured acid value drops to more than 95% of the theoretically calculated value (indicating that the carboxyl group reaction is basically complete), the reaction can be determined as the endpoint. Stop heating and pour the reaction product into 60℃ hot water while it is still hot; the product will solidify rapidly.

[0083] S4 Purification: The solid product was collected and washed three times with hot water to remove unreacted p-methylsalicylic acid and catalyst. Finally, the product was vacuum dried at 55°C for 24 hours to obtain a white waxy solid, which is the p-methylsalicylic acid-PPG oligomer.

[0084] Example 2: Preparation of amphiphilic block oligomers of hydrogenated rosin acid

[0085] (1) Preparation of hydrogenated rosin acid-PEG oligomers

[0086] The principle is the same as in Example 1, but because the carboxyl group of hydrogenated rosin acid has large steric hindrance and relatively low reactivity, a more active catalyst and a slightly higher reaction temperature are required to enable it to undergo esterification with the terminal hydroxyl group of PEG-2000.

[0087] raw material:

[0088] Polyethylene glycol (PEG-2000)

[0089] The molar ratio of hydrogenated rosin acid to polyethylene glycol is 2.2 mol: 1 mol (hydrogenated rosin acid in excess by 10%).

[0090] Esterification catalyst: Tetrabutyl titanate (TBT), added at 1.5% of the mass of hydrogenated rosin acid;

[0091] Antioxidant: Irganox 168, added at 0.3% of the total feed mass.

[0092] Preparation steps:

[0093] S1 Feeding and Dehydration: Add PEG-2000, hydrogenated rosin acid, and antioxidant to the reactor. Under nitrogen protection, heat to 130°C and maintain a vacuum (-0.095MPa) for 40 minutes to ensure complete dehydration.

[0094] S2 esterification reaction: Remove the vacuum and raise the temperature to 190±5℃ under nitrogen protection. At this temperature, slowly add the catalyst tetrabutyl titanate through a constant-pressure dropping funnel. Maintain this temperature for at least 5 hours and monitor the change in acid value.

[0095] S3 endpoint determination and post-processing: The reaction is complete when the acid value drops to more than 95% of the theoretical value. Stop heating and stirring, and pour the molten product into cold n-hexane while it is still hot. A pale yellow viscous substance will immediately precipitate in the solution.

[0096] S4 Purification: The precipitated product was filtered and washed with a small amount of cold n-hexane to completely remove unreacted hydrogenated rosin acid. The product was then vacuum dried at 60°C for 24 hours to obtain a pale yellow, high-viscosity, semi-transparent resinous product, which is the hydrogenated rosin acid-PEG oligomer.

[0097] (2) Preparation of hydrogenated rosin acid-PPG oligomers

[0098] The principle is the same as in Example 1, but due to the large steric hindrance, a highly active catalyst and high temperature are required.

[0099] raw material:

[0100] Polypropylene glycol (PPG-2000)

[0101] The molar ratio of hydrogenated rosin acid to polypropylene glycol is 2.5 mol: 1 mol (hydrogenated rosin acid in excess by 25%).

[0102] Esterification catalyst: Tetraisopropyl titanate (TPT), added at 2.0% of the mass of hydrogenated rosin acid.

[0103] Antioxidant: Irganox 168, added at 0.4% of the total feed mass.

[0104] Preparation steps:

[0105] S1 Feeding and Dehydration: Add PPG-2000, hydrogenated rosin acid, and antioxidant to the reactor. Under nitrogen protection, heat to 120°C and maintain a vacuum (-0.098MPa) for 90 minutes to ensure complete dehydration.

[0106] S2 esterification reaction: Remove the vacuum and raise the temperature to 200±5℃ under nitrogen protection. At this temperature, slowly add the catalyst tetraisopropyl titanate through a constant-pressure dropping funnel. Maintain this temperature for at least 7 hours and monitor the acid value change.

[0107] S3 endpoint determination and post-processing: Stop the reaction when the acid value drops to more than 95% of the theoretical value.

[0108] After the reaction is complete, the hot molten product is slowly poured into approximately four times its volume of an 80% ethanol aqueous solution pre-cooled to 0-5°C under vigorous stirring. The precipitated light yellow viscous solid is the product.

[0109] S4 Purification: The precipitated product was filtered and washed three times with a small amount of cold 50% ethanol aqueous solution. The product was then vacuum dried at 60°C for 24 hours to obtain a pale yellow to amber transparent resin, which is the hydrogenated rosin acid-PPG oligomer.

[0110] Example 3: Preparation of maleic anhydride-grafted polyethylene

[0111] (1) Preparation of medium molecular weight polyethylene grafted with maleic anhydride

[0112] A melt radical grafting method is employed. In the molten state, free radicals are generated using an organic peroxide initiator, which abstract tertiary hydrogen atoms from the polyethylene molecular chain to form polyethylene macromolecular free radicals. These free radicals then react with maleic anhydride monomers, grafting maleic anhydride onto the polyethylene backbone in the form of single or multiple dangling branches.

[0113] raw material:

[0114] medium molecular weight polyethylene

[0115] Maleic anhydride: The amount added is 1.5% of the mass of polyethylene;

[0116] Initiator: dicumyl peroxide (DCP), added at 0.05% of the mass of polyethylene.

[0117] Antioxidant: Pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (Irganox1010), added at 0.1% of the mass of polyethylene.

[0118] Anti-crosslinking agent: styrene, added at 0.5% of the mass of polyethylene.

[0119] Preparation steps:

[0120] S1: Add polyethylene powder, maleic anhydride powder, initiator, antioxidant and synergistic anti-crosslinking agent together into a high-speed mixer.

[0121] Mix at room temperature for 10 minutes to ensure all additives adhere evenly to the surface of the polyethylene granules.

[0122] S2 melt grafting reaction: The premixed material is fed into the twin-screw extruder through a feeder.

[0123] Set the temperature for each zone of the extruder to ensure the reaction completes within the temperature range with the shortest initiator half-life. Example temperature settings are as follows:

[0124] Zone 1 (feeding port): 160℃

[0125] Zone 2 (Melting Zone): 180℃

[0126] Zones 3 to 5 (Reaction Zone): 2000℃

[0127] Zone 6 (Homogenization Zone): 195℃

[0128] Nose: 190℃

[0129] Throughout the process, nitrogen gas is introduced through the feed port to remove oxygen.

[0130] The screw speed is set to 150 rpm to provide sufficient shearing and mixing while controlling the material residence time.

[0131] S3: The strip-shaped product extruded from the die head immediately enters the water tank for cooling; after being dried, it is pelletized to obtain grafted medium molecular weight polyethylene granules.

[0132] (2) Preparation of grafted low molecular weight polyethylene

[0133] The principle is the same as (1).

[0134] raw material:

[0135] Low molecular weight polyethylene

[0136] Maleic anhydride: The amount added is 1.5% of the mass of polyethylene;

[0137] Initiator: dicumyl peroxide (DCP), added at 0.10% of the polyethylene mass.

[0138] Antioxidant: Pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (Irganox1010), added at 0.1% of the mass of polyethylene.

[0139] Anti-crosslinking agent: styrene, added at 0.5% of the mass of polyethylene.

[0140] Preparation steps:

[0141] S1: Add polyethylene powder, maleic anhydride powder, initiator, antioxidant and synergistic anti-crosslinking agent together into a high-speed mixer.

[0142] Mix at room temperature for 10 minutes to ensure all additives adhere evenly to the surface of the polyethylene granules.

[0143] S2 melt grafting reaction: The premixed material is fed into the twin-screw extruder through a feeder.

[0144] Set the temperature for each zone of the extruder to ensure the reaction completes within the temperature range with the shortest initiator half-life. Example temperature settings are as follows:

[0145] Zone 1 (feeding port): 150℃

[0146] Zone 2 (Melting Zone): 170℃

[0147] Zones 3 to 5 (Reaction Zone): 190℃

[0148] Zone 6 (Homogenization Zone): 185℃

[0149] Head: 180℃

[0150] Throughout the process, nitrogen gas is introduced through the feed port to remove oxygen.

[0151] The screw speed is set to 200 rpm to provide sufficient shearing and mixing while controlling the material residence time.

[0152] S3: The strip-shaped product extruded from the die head immediately enters the water tank for cooling; after being dried, it is granulated to obtain grafted low molecular weight polyethylene granules.

[0153] (3) Preparation of grafted polyethylene wax

[0154] The principle is the same as (1).

[0155] raw material:

[0156] Polyethylene wax maleic anhydride: The amount added is 1.5% of the mass of polyethylene;

[0157] Initiator: dicumyl peroxide (DCP), added at 0.02% of the mass of polyethylene.

[0158] Antioxidant: Pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (Irganox1010), added at 0.1% of the mass of polyethylene.

[0159] Preparation steps:

[0160] S1: Add polyethylene powder, maleic anhydride powder, initiator, antioxidant and synergistic anti-crosslinking agent together into a high-speed mixer.

[0161] Mix at room temperature for 10 minutes to ensure all additives adhere evenly to the surface of the polyethylene granules.

[0162] S2 melt grafting reaction: The premixed material is fed into the twin-screw extruder through a feeder.

[0163] Set the temperature for each zone of the extruder to ensure the reaction completes within the temperature range with the shortest initiator half-life. Example temperature settings are as follows:

[0164] Zone 1 (feeding port): 130℃

[0165] Zone 2 (Melting Zone): 150℃

[0166] Zones 3 to 5 (Reaction Zone): 170℃

[0167] Zone 6 (Homogenization Zone): 165℃

[0168] Head: 160℃

[0169] Throughout the process, nitrogen gas is introduced through the feed port to remove oxygen.

[0170] The screw speed is set to 200 rpm to provide sufficient shearing and mixing while controlling the material residence time.

[0171] S3: The strip-shaped product extruded from the die head immediately enters the water tank for cooling; after being dried, it is granulated to obtain grafted polyethylene wax granules.

[0172] The grafting rate of each particle was determined by chemical titration. The grafting rate of medium molecular weight polyethylene was 1.2%; the grafting rate of low molecular weight polyethylene was 1.4%; and the grafting rate of polyethylene wax was 1.7%.

[0173] Example 4: Preparation of Composite Polyethylene Material

[0174] This embodiment utilizes a twin-screw extruder to prepare composite polymerized polyethylene material, with specific dosages shown in Table 1 below.

[0175] The steps are as follows:

[0176] S1 Premixing and Feeding: Pour the weighed polyethylene, toughening agent, and antioxidant into a high-speed mixer and mix for 5 minutes at room temperature to ensure uniformity. Transfer the mixed solid material to a loss-in-weight feeder.

[0177] S2 extruder temperature settings: From the feed port to the die head, set the following temperatures:

[0178] Zone 1 (feeding port): 170℃

[0179] Zone 2 (Melting Zone): 190℃

[0180] Zones 3 to 5 (Melting and Reaction Zones): 210℃

[0181] Zone 6 (Homogenization and Pressure Building Zone): 200℃

[0182] Nose: 190℃

[0183] S3 Solid Feeding and Melting: Start the twin-screw extruder. After the temperature of each zone reaches the set value, the premixed solid material is stably fed into the main feed port of the extruder through a loss-in-weight feeder.

[0184] Precise injection of S4 liquid oligomers: The p-methylsalicylic acid amphiphilic block oligomer and the hydrogenated rosin acid amphiphilic block oligomer are separately (or pre-mixed evenly) loaded into the tank of the liquid injection pump.

[0185] As the solid material advances through the extruder to the fully molten section (zone three or four), a mixture of the two oligomers is injected at a constant rate into the molten polymer matrix through a precision liquid injection pump via an injection port located on the barrel.

[0186] S5 Melt Blending and Deviation: Under the action of the screw's kneading block, each component is fully dispersed and mixed evenly. A vacuum deviation port is set after the injection port, and a certain vacuum degree (-0.08MPa) is applied to extract any small molecule volatiles that may remain.

[0187] S6 Extrusion, Cooling and Pelletizing: The fully blended and devolatilized molten material is extruded into strips through a die and immediately enters a cooling water tank for cooling and solidification. After drying, it is cut into uniform pellets by a pelletizer.

[0188] S7 Packaging: After drying, the cut granules are collected and packaged by a cyclone separator to obtain the high-performance composite PE material.

[0189] Table 1. Composition ratio of composite polyethylene materials

[0190]

[0191] Table 1 (continued) Composite Polyethylene Material Proportions

[0192]

[0193] Performance testing of composite polyethylene materials includes the following aspects:

[0194] The impact strength of the cantilever beam was tested at room temperature (25℃) and low temperature (-30℃), and the test method was in accordance with GB / T 1843-2008 Determination of Impact Strength of Plastic Cantilever Beams.

[0195] Tensile strength and elongation at break at room temperature (25℃) and low temperature (-30℃) were tested according to GB / T1040.2-2022 Determination of tensile properties of plastics - Part 2: Test conditions for molded and extruded plastics.

[0196] The test results are shown in Table 2.

[0197] Table 2 Performance test results of composite polyethylene materials

[0198]

[0199] Based on the data in Tables 1 and 2, the performance test results of the composite polyethylene materials showed significant differences under different serial numbers. These differences mainly stemmed from variations in the component ratios of each group, particularly the molecular weight of polyethylene, the type of grafted polyethylene, the amount of toughening agent, and the type and amount of amphiphilic block oligomers. Combining the component differences in Table 1 with a detailed analysis of the reasons for the performance changes in Table 2, this invention identifies the following factors:

[0200] 1. The effect of high molecular weight polyethylene (HMWPE) content

[0201] Numbers 9, 10, and 12: These numbers contain zero high-molecular-weight polyethylene (HMWPE), replaced by grafted medium-molecular-weight polyethylene (CMPE) or grafted low-molecular-weight polyethylene (LMPE) as the main component. Performance tests show that the impact strength, tensile strength, and elongation at break of these numbers are significantly lower than those of number 1. This indicates that HMWPE is crucial for maintaining the material's high strength and toughness, and its absence leads to a severe decline in material performance.

[0202] 2. Effects of grafted polyethylene type and dosage

[0203] In item 1, 8 parts of grafted low molecular weight polyethylene were used, resulting in excellent performance. In contrast, item 7, using grafted medium molecular weight polyethylene, showed a slight decrease in performance, and item 8, using grafted polyethylene wax, showed a further decrease in performance. This is because low molecular weight polyethylene is more easily dispersed in the matrix after grafting, effectively improving interfacial compatibility. In contrast, the grafted products of medium molecular weight polyethylene and polyethylene wax have lower molecular weights, which may lead to insufficient compatibility or the formation of defects, thus reducing mechanical properties.

[0204] The grafting rates measured in Example 3 show that, although there are differences in the grafting rates of the three types of polyethylene, they are relatively close. However, the grafted polyethylene wax, due to its low molecular weight, has a high grafting rate but poor strength, which weakens the overall performance. Therefore, the molecular weight of the grafted polyethylene has a significant impact on its performance, and grafting low molecular weight polyethylene is the most effective in improving compatibility and toughness.

[0205] 3. Effects of the type and amount of amphiphilic block oligomers

[0206] Using p-methylsalicylic acid-PEG oligomers and hydrogenated rosin acid-PEG oligomers resulted in superior performance compared to item 3 (using PPG-based oligomers). This is because PEG has primary hydroxyl groups at its end, which have high reactivity, allowing the resulting oligomers to be more compatible with the polyethylene matrix. In contrast, PPG has secondary hydroxyl groups with low reactivity, leading to poorer oligomer compatibility and thus slightly inferior performance.

[0207] Oligomer 1, using both p-methylsalicylic acid-PEG and hydrogenated abietic acid-PEG oligomers, exhibits the best performance. Oligomer 4, using only hydrogenated abietic acid-PEG oligomers, and oligomer 5, using only p-methylsalicylic acid-PEG oligomers, both show lower performance than oligomer 1. This indicates that the two oligomers have a synergistic effect, jointly improving interfacial adhesion and stress dispersion.

[0208] In item 6, using pure PEG-2000 instead of oligomers resulted in the worst performance. This is because pure PEG-2000 lacks end-group modification, making it unable to act as an effective compatibilizer. Its poor compatibility with other components leads to phase separation. Furthermore, it lacks the buffering effect provided by a rigid structure, ultimately contributing to the performance degradation.

[0209] Finally, looking at items 1-3, 7-12, and 4, 5, and 6, the degree of performance degradation at low temperatures differs significantly. Since the proportions of the two oligomers used in items 2, 3, and 7-12 are known, their degradation levels are roughly the same as item 1. However, items 4, 5, and 6 show significant differences compared to item 1. The core reason for this is the different states and energy dissipation capabilities of the interfacial phases constructed by each component at low temperatures. Item 1, serving as the benchmark, uses both p-methylsalicylic acid-PEG and hydrogenated rosin acid-PEG oligomers. These two oligomers are "anchored" to the polyethylene matrix in different modes through their rigid aromatic or alicyclic end groups, while the flexible PEG segments together form a robust and complete interfacial network. At -30℃, this network can still effectively transfer and disperse stress, thus exhibiting the best low-temperature performance retention. In contrast, numbers 4 and 5 use only a single type of oligomer, resulting in a limited interfacial toughening mechanism. Number 4 contains only hydrogenated rosin acid-PEG, which is compatible with POE, but lacks the "aromatic ring-PE" binding site of p-methylsalicylic acid-PEG, weakening the interfacial bonding between the oligomer and the PE matrix. At low temperatures, the rigidity of the PE molecular chain further increases, making the interface between the oligomer and PE prone to micro-gaps (stress concentration points). When subjected to impact, stress preferentially accumulates at these micro-gaps, leading to earlier crack initiation. Although POE can still absorb some stress, the interfacial transfer efficiency decreases, exacerbating performance degradation. Number 5 contains only p-methylsalicylic acid-PEG, which binds well with PE, but lacks the "alicyclic structure-POE" binding site of hydrogenated rosin acid-PEG, significantly weakening the interfacial bonding between the oligomer and POE. At low temperatures, the elasticity of POE decreases (approaching its glass transition temperature). Without tight binding with the oligomer, POE easily aggregates in the PE matrix (losing its role as an elastic dispersed phase). When the material is subjected to impact, the aggregated POE cannot absorb stress, and the stress acts directly on the rigid PE matrix, causing cracks to propagate rapidly and the degradation rate to increase further. The root cause of the problem in item 6, which shows a precipitous decline in performance, lies in the use of pure PEG-2000. It has extremely poor compatibility with the non-polar polyethylene matrix and forms independent crystalline phase regions. At low temperatures, these PEG phase regions are completely "frozen" into hard defect points, becoming sources of stress concentration. This makes cracks very easy to initiate and rapidly propagate, ultimately leading to catastrophic brittle fracture of the material at low temperatures.

[0210] The above detailed description is a specific description of one of the feasible embodiments of the present invention. This embodiment is not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included within the scope of the technical solution of the present invention.

Claims

1. A PE material, characterized in that, It contains the following ingredients based on parts by weight: High molecular weight polyethylene, 70-90 parts Maleic anhydride-grafted low molecular weight polyethylene, 8-15 parts Toughening agent, 20-30 parts p-Methylsalicylic acid amphiphilic block oligomer, 1-2 parts Hydrogenated rosin acid amphiphilic block oligomer, 1-2 parts Antioxidant, 0.5-1 part; The high molecular weight polyethylene has a weight-average molecular weight of 300K-320K and a molecular weight distribution of K≤2.

5. The maleic anhydride-grafted low molecular weight polyethylene has a maximum weight-average molecular weight of 120K and a molecular weight distribution of Đ≤2.

5. The p-methylsalicylic acid amphiphilic block oligomer is an oligomer with a flexible segment linked to two p-methylsalicylic acid residues. The hydrogenated rosin acid amphiphilic block oligomer is an oligomer in which a flexible segment is linked to two hydrogenated rosin acid residues.

2. The PE material according to claim 1, characterized in that, The flexible segment is an aliphatic polyether segment; and the number average molecular weight is ≤2000.

3. The PE material according to claim 2, characterized in that, The aliphatic polyether segment is polyethylene glycol or polypropylene glycol.

4. The PE material according to claim 1, characterized in that, The maleic anhydride-grafted low molecular weight polyethylene is prepared by grafting maleic anhydride onto polyethylene, and its grafting rate is ≤1.5%.

5. The PE material according to claim 1, characterized in that, The p-methylsalicylic acid amphiphilic block oligomer was prepared by condensation reaction of p-methylsalicylic acid with flexible segments under catalytic conditions.

6. The PE material according to claim 1, characterized in that, The hydrogenated rosin acid amphiphilic block oligomer was prepared by condensation reaction of hydrogenated rosin acid with flexible segments under catalytic conditions.

7. The method for preparing the PE material according to any one of claims 1-6, characterized in that, High molecular weight polyethylene, maleic anhydride-grafted low molecular weight polyethylene, toughening agents, and antioxidants are fed into a screw extruder via a feeder. P-methylsalicylic acid amphiphilic block oligomer and hydrogenated rosin acid amphiphilic block oligomer are precisely injected into the screw extruder through a liquid injection port in the melting section. The screw extruder is then used for melt blending, extrusion, cooling, drying, and pelletizing to produce PE material.

8. The use of the PE material according to any one of claims 1-6 in the preparation of packaging materials.

9. The application according to claim 8, wherein the packaging material is pharmaceutical packaging.

10. A reagent bottle, characterized in that... Made of the PE material as described in any one of claims 1-6.

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