Polymethyl methacrylate composition and preparation method thereof

Abstract

The invention relates to the technical field of high polymer materials, and discloses a polymethyl methacrylate composition and a preparation method thereof, and the polymethyl methacrylate composition is prepared from the following raw materials in parts by weight: 100 parts of polymethyl methacrylate resin, 0.2-3.2 parts of a Lewis acid center provider, 0.2-3.2 parts of a multifunctional bridging ligand, and 0.1-1.1 parts of a competitive replacement aid. The preparation method comprises the step of carrying out melt blending on the components. According to the invention, through the synergistic effect of the Lewis acid center provider and the multifunctional bridging ligand, a dynamic reversible supramolecular network is constructed in a polymethyl methacrylate matrix, and the structure of the supramolecular network effectively improves the impact toughness, rigidity and thermal deformation temperature of the material. The technical problem that toughness, rigidity, heat resistance and processability of a traditional polymethyl methacrylate material are difficult to consider at the same time is solved, and the polymethyl methacrylate composition with excellent comprehensive performance is prepared.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a polymethyl methacrylate composition and its preparation method. Background Technology

[0002] Polymethyl methacrylate (PMMA) is widely used in optics, construction, automotive, and electronics due to its excellent optical transparency, good weather resistance, and high surface hardness. However, as an amorphous polymer, PMMA's molecular chain structure results in inherent brittleness and poor notched impact toughness, which severely limits its applications in situations requiring impact loads or as structural components.

[0003] To mitigate the brittleness of PMMA, existing technologies employ blending modification methods, such as introducing methyl methacrylate-butadiene-styrene copolymers or acrylate core-shell elastomers as toughening agents. While this method effectively improves the material's impact toughness, the introduction of toughening agents significantly reduces the material's rigidity, hardness, and heat resistance. Furthermore, due to the refractive index mismatch between the toughening agent and the PMMA matrix, light scattering occurs at the interface, leading to decreased light transmittance and increased haze in the blend, thus sacrificing the core optical properties of PMMA.

[0004] On the other hand, PMMA's low heat distortion temperature limits its use in higher temperature environments. Modifications to improve PMMA's heat resistance and other mechanical properties, such as constructing strong interaction networks, while achieving the desired effect, drastically increase the material's viscosity in the molten state. Excessively high melt viscosity leads to poor processing flowability, causing difficulties in molding processes such as injection molding and extrusion. This not only increases energy consumption and equipment load but also easily leads to product defects. Therefore, existing technologies consistently face the technical challenge of simultaneously achieving high impact toughness, high rigidity, high heat resistance, high transparency, and good processing flowability in PMMA materials. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a polymethyl methacrylate composition and its preparation method, which solves the problem of balancing the impact toughness, rigidity, heat resistance, optical transparency, and processing fluidity of traditional polymethyl methacrylate materials.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a polymethyl methacrylate composition and its preparation method.

[0007] In a first aspect, the present invention provides a polymethyl methacrylate composition, which adopts the following technical solution: A polymethyl methacrylate composition, made from raw materials comprising the following parts by weight: 100 parts by weight of polymethyl methacrylate resin; Lewis acid centers provide 0.2-3.2 parts by weight; Multifunctional bridging ligands, 0.2-3.2 parts by weight; And 0.1-1.1 parts by weight of competitive displacement agent.

[0008] By employing the above technical solution, this invention constructs a dynamically reversible supramolecular network within a polymethyl methacrylate matrix. This supramolecular network, through synergistic effects, endows the composition with comprehensive properties including high impact toughness, high rigidity, high heat resistance, high transparency, and good processing flowability. Its mechanism of action is as follows: Construction of supramolecular networks: During melt blending, the Lewis acid center provides the metal cation in the polymer as a Lewis acid site, which coordinates with the carbonyl oxygen on the polymethyl methacrylate (PMMA) molecular chain to form an initial anchor point. Simultaneously, the multiple functional groups on the multifunctional bridging ligand molecule can coordinate with metal cations at different anchor points and form hydrogen bonds with other ligands or groups on the PMMA molecular chain.

[0009] Through the synergistic effect of metal coordination and hydrogen bonding, a three-dimensional, non-covalently cross-linked supramolecular network was constructed in a polymethyl methacrylate matrix. The supramolecular network effectively confines the movement of molecular chains in the solid state, thereby significantly improving the material's rigidity and heat distortion temperature. Meanwhile, the non-covalent bonds in the network can dissociate and recombine when subjected to external impact, effectively dissipating impact energy and thus endowing the material with excellent impact toughness.

[0010] Control of processing performance: While the aforementioned supramolecular network imparts excellent properties to the material, it also leads to a sharp increase in its melt viscosity, which is detrimental to processing and molding. The competitive substitution agent introduced in this invention contains functional groups on its molecule that can reversibly interact with Lewis acid centers.

[0011] Under high-temperature processing conditions, competitive substitution agent molecules can competitively and reversibly coordinate with metal cations on the carbonyl groups of polymethyl methacrylate molecular chains, thereby temporarily reducing the crosslinking density and strength of the supramolecular network.

[0012] This dynamic competitive displacement significantly reduces the viscosity of the composition in the molten state and improves its processing flowability. Once the material cools and solidifies, this competitive effect weakens, allowing the stable supramolecular network to be reconstructed, thus ensuring that the final product retains excellent mechanical and thermal properties.

[0013] Preferably, the weight ratio of the Lewis acid center provider to the multifunctional bridging ligand is (1.0-1.5):1.

[0014] By employing the above technical solution, the stoichiometric relationship between nodes and bridging agents in the supramolecular network was precisely controlled. A specific weight ratio ensures sufficient Lewis acid centers in the system, allowing for effective coordination of functional groups on the multifunctional bridging ligands, thus facilitating the formation of a more complete and uniformly distributed supramolecular network. An optimized network can more efficiently transfer stress and dissipate energy, thereby maximizing the improvement in impact toughness, rigidity, and heat resistance of the composition.

[0015] Preferably, the Lewis acid center is provided with a body selected from one or more of zinc stearate, zinc laurate, zinc acetylacetonate, magnesium stearate, aluminum stearate, and aluminum acetylacetonate; The multifunctional bridging ligand is selected from one or more of melamine, isocyanate, guanine, urea, dicyandiamide, and adipamide hydrazide. The competitive substitution agent is selected from one or more of ethylene bis-stearamide, erucamide, oleamide, pentaerythritol, and glyceryl monostearate.

[0016] By adopting the above technical solution, a variety of specific and feasible raw material options are provided. These raw materials are widely available and can effectively achieve the technical effects of the present invention, thus having good industrial applicability.

[0017] Secondly, the present invention provides a method for preparing a polymethyl methacrylate composition, which adopts the following technical solution: A method for preparing the polymethyl methacrylate composition according to any one of the preceding claims, comprising the following steps: The polymethyl methacrylate resin is subjected to a drying pretreatment. The Lewis acid center donor, multifunctional bridging ligand, and competitive displacement agent are subjected to drying pretreatment. The polymethyl methacrylate resin, the Lewis acid center donor, the multifunctional bridging ligand, and the competitive displacement agent are mixed and then melt-blended at a temperature of 210°C-245°C.

[0018] By employing the above technical solution, a highly efficient, stable, and industrially applicable preparation method is provided. In this method, the dynamic supramolecular network can be constructed in situ within the polymer matrix through a one-step melt blending process. The selected temperature range ensures complete melting of the polymethyl methacrylate resin, providing the necessary conditions for uniform dispersion and interaction of the components at the molecular level, while effectively activating the function of the competitive displacement agent to ensure the system has a suitable processing viscosity, and simultaneously avoiding material degradation caused by excessively high temperatures.

[0019] Preferably, the polymethyl methacrylate resin is dried at a temperature of 80°C-95°C for 3-5 hours. The Lewis acid center provider, multifunctional bridging ligand, and competitive displacement agent are dried at a temperature of 60°C-80°C for 1-2 hours.

[0020] By adopting the above technical solution, the moisture contained in the raw materials can be removed in advance, which can effectively prevent the hydrolysis of polymethyl methacrylate during high-temperature processing and avoid moisture from interfering with the coordination of Lewis acid and the formation of hydrogen bond network, thereby ensuring the stability of the final product performance and the consistency between batches.

[0021] Preferably, the melt blending step is carried out in a twin-screw extruder, wherein the screw speed of the twin-screw extruder is 250-500 rpm, and the barrel temperature distribution is as follows: The feeding section is 180℃-200℃, the mixing and reaction section is 225℃-245℃, and the die head is 220℃-240℃.

[0022] By adopting the above technical solution and utilizing the high-intensity shearing and mixing action provided by the twin-screw extruder, it is possible to ensure that all auxiliary components are uniformly dispersed at the microscale in the polymethyl methacrylate melt, thus guaranteeing the formation of a homogeneous and efficient supramolecular network structure. The set process parameter range provides an optimized process window for achieving sufficient mixing, reaction, and flowability control.

[0023] This invention provides a polymethyl methacrylate composition and its preparation method. It has the following beneficial effects: 1. This invention constructs a dynamically reversible supramolecular network in a polymethyl methacrylate matrix using Lewis acid center donors and multifunctional bridging ligands. The supramolecular network exerts physical cross-linking in the solid state, effectively restricting the macroscopic movement of molecular chains. This improves impact toughness while avoiding or even improving tensile strength and flexural modulus. Compared with traditional elastomer toughening schemes such as MBS, the supramolecular network does not introduce light scattering centers. Therefore, the composition still maintains the excellent optical transparency of polymethyl methacrylate, resolving the contradiction between toughening and transparency.

[0024] 2. This invention generates an additional binding effect on the segmental movement of polymethyl methacrylate (PMMA) molecular chains through non-covalent interactions in the supramolecular network. This binding enhances the material's resistance to deformation when heated, thereby effectively increasing the heat distortion temperature. Compared with pure PMMA, the composition of this invention can still maintain better dimensional stability at high temperatures. This makes the composition a potential application in scenarios with higher requirements for heat resistance, such as lighting components, appliance housings, or automotive interiors.

[0025] 3. This invention introduces a competitive substitution agent into the supramolecular network system. Under high-temperature melt processing conditions, the competitive substitution agent can reversibly compete with Lewis acid centers for coordination, temporarily reducing the crosslinking density of the supramolecular network. This dynamic dissociation and recombination mechanism effectively reduces the viscosity of the melt, enabling the composition to have good melt index and processing fluidity without affecting the mechanical and thermal properties of the final product. This facilitates injection molding, extrusion, and other molding processes, improving production efficiency and molding yield. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to embodiments, comparative examples, and test examples. 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.

[0027] Examples 1-5: Example

[0028] This embodiment provides a method for preparing a polymethyl methacrylate composition, using the following raw materials in parts by weight: PMMA-1: 98 copies Zinc stearate: 1.0 part Melamine: 0.8 parts Ethylene bis-stearamide: 0.2 parts The specific preparation steps include: Pretreatment: Dry PMMA-1 resin in a forced-air oven at 85°C for 4 hours; dry zinc stearate, melamine and ethylene bis-stearamide in an oven at 70°C for 2 hours.

[0029] Melt blending: All the pretreated raw materials are simultaneously fed into a co-rotating twin-screw extruder with a length-to-diameter ratio of 40:1 via a loss-in-weight feeder. The extruder screw speed is set to 300 rpm, and the temperatures of each section are as follows: feeding section 190℃, melting section 220℃, mixing and reaction section 240℃, metering section and die head 230℃.

[0030] Post-processing: The molten strip extruded from the die head is introduced into a water tank for cooling, and then cut into pellets by a pelletizer to obtain the final composite pellets. Example

[0031] This embodiment provides a method for preparing a polymethyl methacrylate composition, using the following raw materials in parts by weight: PMMA-1: 96 copies Zinc acetylacetone: 2.0 parts Melamine: 1.5 parts Ethylene bis-stearamide: 0.5 parts The specific preparation steps include: Pretreatment: Dry PMMA-1 resin in a forced-air oven at 85°C for 4 hours; dry zinc acetylacetonate, melamine and ethylene bis-stearamide in an oven at 70°C for 2 hours.

[0032] Melt blending: All the pretreated raw materials were simultaneously fed into a co-rotating twin-screw extruder with a length-to-diameter ratio of 40:1 via a loss-in-weight feeder. The extruder screw speed was set to 400 rpm, and the temperature settings for each section were the same as in Example 1.

[0033] Post-processing: The molten strip extruded from the die head is introduced into a water tank for cooling, and then cut into pellets by a pelletizer to obtain the final composite pellets. Example

[0034] This embodiment provides a method for preparing a polymethyl methacrylate composition, using the following raw materials in parts by weight: PMMA-2: 97 copies Zinc stearate: 1.5 parts Urea: 1.0 part Pentaerythritol: 0.5 parts The specific preparation steps include: Pretreatment: Dry PMMA-2 resin in a forced-air oven at 85°C for 4 hours; dry zinc stearate, urea and pentaerythritol in an oven at 70°C for 2 hours.

[0035] Melt blending: All the pretreated raw materials were simultaneously fed into a co-rotating twin-screw extruder with a length-to-diameter ratio of 40:1 via a loss-in-weight feeder. The extruder screw speed was set to 350 rpm, and the temperature settings for each section were the same as in Example 1.

[0036] Post-processing: The molten strip extruded from the die head is introduced into a water tank for cooling, and then cut into pellets by a pelletizer to obtain the final composite pellets. Example

[0037] This embodiment provides a method for preparing a polymethyl methacrylate composition, using the following raw materials in parts by weight: PMMA-1: 95 servings Magnesium stearate: 2.5 parts Adipic acid hydrazide: 2.0 parts Ethylene bis-stearamide: 0.5 parts The specific preparation steps include: Pretreatment: Dry PMMA-1 resin in a forced-air oven at 85°C for 4 hours; dry magnesium stearate, adipamide, and ethylene bis-stearamide in an oven at 70°C for 2 hours.

[0038] Melt blending: All the pretreated raw materials were simultaneously fed into a co-rotating twin-screw extruder with a length-to-diameter ratio of 40:1 via a loss-in-weight feeder. The extruder screw speed was set to 400 rpm, and the temperature settings for each section were the same as in Example 1.

[0039] Post-processing: The molten strip extruded from the die head is introduced into a water tank for cooling, and then cut into pellets by a pelletizer to obtain the final composite pellets. Example

[0040] This embodiment provides a method for preparing a polymethyl methacrylate composition, using the following raw materials in parts by weight: PMMA-1: 98.9 copies Zinc stearate: 0.5 parts Melamine: 0.5 parts Ethylene bis-stearamide: 0.1 parts The specific preparation steps include: Pretreatment: Dry PMMA-1 resin in a forced-air oven at 85°C for 4 hours; dry zinc stearate, melamine and ethylene bis-stearamide in an oven at 70°C for 2 hours.

[0041] Melt blending: All the pretreated raw materials were simultaneously fed into a co-rotating twin-screw extruder with a length-to-diameter ratio of 40:1 via a loss-in-weight feeder. The extruder screw speed was set to 300 rpm, and the temperature settings for each section were the same as in Example 1.

[0042] Post-processing: The molten strip extruded from the die head is introduced into a water tank for cooling, and then cut into pellets by a pelletizer to obtain the final composite pellets.

[0043] Comparative Examples 1-5: Among them: zinc stearate, zinc acetylacetone, and magnesium stearate provide the body for Lewis acid centers; Melamine, urea, and adipic acid hydrazide are multifunctional bridging ligands; Ethylene bis-stearamide and pentaerythritol are competitive displacement agents.

[0044] Comparative Example 1: Compared with Example 1, the difference is that this comparative example only uses 100 parts by weight of PMMA-1 resin, without adding Lewis acid center donors, multifunctional bridging ligands and competitive displacement agents, and the dried PMMA-1 resin is directly used for injection molding.

[0045] Comparative Example 2: Compared with Example 1, the difference is that this comparative example does not adopt the technical solution of the present invention, but uses the conventional MBS resin toughening method in the prior art. The composition is 90 parts by weight of PMMA-1 and 10 parts by weight of MBS resin, and the melt blending and subsequent steps in the preparation method are the same as in Example 1.

[0046] Comparative Example 3: Compared with Example 1, the difference is that the composition of this comparative example lacks the key multifunctional bridging ligand. It consists of 99.0 parts by weight of PMMA-1 and 1.0 parts by weight of zinc stearate, without the addition of the multifunctional bridging ligand and competitive displacement agent; the remaining preparation steps are the same as in Example 1.

[0047] Comparative Example 4: Compared with Example 1, the difference is that the composition of this comparative example lacks the key Lewis acid center donor. It consists of 99.2 parts by weight of PMMA-1 and 0.8 parts by weight of melamine, without the addition of the Lewis acid center donor and competing displacement agent; the remaining preparation steps are the same as in Example 1.

[0048] Comparative Example 5: Compared with Example 1, the difference is that the composition of this comparative example lacks a competitive displacement agent. The composition is 98.2 parts by weight of PMMA-1, 1.0 parts by weight of zinc stearate and 0.8 parts by weight of melamine, and the remaining preparation steps are the same as in Example 1.

[0049] Test Example 1-2: Test Example 1: Feasibility Verification Test for Dynamic Network Formation of the Composition To verify the feasibility of the supramolecular dynamic network in the technical solution of the present invention, dynamic mechanical property (DMA) and melt rheological property analysis were performed on the samples prepared from the composition particles of Example 1, Comparative Example 1 and Comparative Example 5.

[0050] Experimental methods: Dynamic mechanical property analysis: A dynamic mechanical analyzer was used to test injection-molded specimens measuring 30mm × 10mm × 3mm. The test mode was a single cantilever beam, and the test parameters were set as follows: test frequency 1Hz, strain amplitude 0.1%, heating rate 3℃ / min, and temperature scan range 30℃ to 180℃. The storage modulus (G) of the sample was recorded. 1 ), loss modulus (G) 2 ) and loss factor (tan r Glass transition temperature (T) varies with temperature. g ) by tan r The peak temperature is determined.

[0051] Melt rheological property analysis: The viscoelastic behavior of the samples in the molten state was tested using a rotational rheometer. The composition particles were molded into discs with a diameter of 25 mm and a thickness of 1 mm at 230 °C. A parallel plate geometry was used for the test, and frequency scanning was performed at 230 °C under nitrogen protection. The strain amplitude was set to 1% to ensure the test was conducted within the linear viscoelastic region. The angular frequency scan range was 0.01 rad / s to 100 rad / s. The storage modulus (G) of the samples was recorded. 1 ), loss modulus (G) 2 ) and complex viscosity (h n ) with the change of angular frequency.

[0052] Experimental data: Table 1. Dynamic Mechanical Performance Analysis Test Data Test sample <![CDATA[T g (tan r Peak value, ℃) <![CDATA[Storage modulus G 1 40℃ (GPa)]]> <![CDATA[Storage modulus G 1 150℃ (MPa)]]> Comparative Example 1 106.2 2.15 0.28 Comparative Example 5 119.8 2.51 2.13 Example 1 118.5 2.46 1.95 Table 2. Test data of melt rheological properties (230℃) Test sample <![CDATA[Complex viscosity η n 0.1rad / s (Pa·s)]]> <![CDATA[Complex viscosity η n 100rad / s (Pa·s)]]> <![CDATA[G 1 -G 2 Crosslinking point angular frequency w c (rad / s) Comparative Example 1 <![CDATA[1.1×10 3 ]]> <![CDATA[3.5×10 2 ]]> 8.5 Comparative Example 5 <![CDATA[9.8×10 4 ]]> <![CDATA[5.1×10 2 ]]> 0.12 Example 1 <![CDATA[4.5×10 4 ]]> <![CDATA[4.8×10 2 ]]> 0.47 in conclusion: The test results of dynamic mechanical properties and melt rheological properties provide objective data support for the formation and controllability of the supramolecular dynamic network in this technical solution.

[0053] As shown in Table 1, compared with the unmodified Comparative Example 1, the glass transition temperatures of Comparative Example 5 and Example 1, which contain Lewis acid center donors and multifunctional bridging ligands, are all increased. This indicates that the segmental motion of the PMMA molecular chain is subject to additional constraints. More crucial data is the storage modulus at 150°C. The G of Comparative Example 1... 1 150℃The values ​​are extremely low, exhibiting typical mechanical behavior of amorphous linear polymers entering the viscous flow state. However, Comparative Example 5 and Example 1 still maintain high storage moduli at this temperature, forming a clear rubbery plateau, which is direct evidence of the existence of a three-dimensional network structure within the material. The three-dimensional network structure restricts the macroscopic flow of molecular chains, thereby endowing the material with high modulus at high temperatures.

[0054] As shown in Table 2, the dynamic characteristics of the network are evident in the molten state at 230℃. Compared to Comparative Example 1, Comparative Example 5 exhibits a complex viscosity nearly two orders of magnitude higher in the low-frequency region, and G... 1 -G 2 The crosslinking point angular frequency decreased significantly, exhibiting gel-like behavior, indicating that the combination of Lewis acid center donor and multifunctional bridging ligand formed an effective supramolecular network in the melt. The comparison between Example 1 and Comparative Example 5 reveals the mechanism of action of the competitive displacement agent. In Example 1, after the addition of the competitive displacement agent, the viscosity in the low-frequency region decreased significantly compared to Comparative Example 5, while w c The frequency shifts towards higher frequencies. This indicates that under high-temperature processing conditions, the competitive displacement agent effectively reduces the crosslinking density of the main network through reversible competitive interactions with it, thereby improving melt flowability. In the high-frequency region, the viscosity of all samples tends to be similar, indicating that the main network dissociates at high shear rates, exhibiting dynamic reversibility.

[0055] Based on the above analysis, the data in Table 1 confirms that a thermally stable supramolecular network was successfully constructed in the composition of the present invention in the solid state; the melt rheological data further confirms the dynamic reversibility of the supramolecular network at the melt processing temperature, as well as the effective regulation of network strength by the competitive substitution agent, thereby verifying the feasibility of the technical solution of the present invention.

[0056] Test Example 2: Performance Comparison Test Between the Example and the Comparative Example To evaluate the overall performance of the compositions of the present invention and to compare them with existing technologies and formulations lacking key components, the composition particles of Examples 1-5 and Comparative Examples 1-5 were injection molded into specimens according to standard methods, and their mechanical, thermal, processability and optical properties were tested.

[0057] Experimental methods: Sample preparation: After drying the composition particles of each example and comparative example at 85°C for 4 hours, standard samples for various tests were prepared using an injection molding machine. The injection molding process parameters were: melt temperature 230°C, mold temperature 70°C.

[0058] Performance testing: Notched impact strength of cantilever beam: tested according to ASTM D256 standard.

[0059] Tensile strength and tensile modulus: tested according to ASTM D638 standard.

[0060] Bending strength and bending modulus: tested according to ASTM D790 standard.

[0061] Rockwell hardness: Tested according to ASTM D785 standard using the R scale.

[0062] Heat distortion temperature (HDT): Tested according to ASTM D648 standard under a load of 1.82 MPa.

[0063] Melt Flow Index (MFI): Tested according to ASTM D1238 standard at 230°C and 3.8 kg load.

[0064] Light transmittance and haze: Tested according to ASTM D1003 standard using 3mm thick injection molded samples.

[0065] Experimental data: Table 3. Overall performance test data of each embodiment and comparative example Test sample Notched impact strength (kJ / m²) Tensile strength (MPa) Flexural modulus (GPa) Rockwell hardness (R) HDT (°C) MFI (g / 10min) Light transmittance (%) Example 1 12.1 79 3.5 115 111 3.5 92.1 Example 2 15.8 75 3.4 112 114 2.9 91.8 Example 3 11.5 82 3.6 116 109 10.2 92.0 Example 4 14.2 77 3.5 113 113 2.5 91.5 Example 5 8.9 80 3.4 114 108 4.1 92.2 Comparative Example 1 1.6 78 3.3 118 96 2.1 92.5 Comparative Example 2 13.5 62 2.5 98 89 3.1 88.3 Comparative Example 3 2.1 78 3.3 117 98 2.0 92.4 Comparative Example 4 2.5 79 3.4 119 97 2.2 91.9 Comparative Example 5 12.5 80 3.6 116 112 0.8 92.0 in conclusion: The comprehensive performance test data in Table 3 systematically verifies the superiority of the technical solution of this invention over existing technologies and incomplete formulations.

[0066] First, the comparison between Examples 1-5 and Comparative Examples 1 and 2 reveals that the present invention solves the technical problem of mutually exclusive performance. The notched impact strength of the Examples is much higher than that of Comparative Example 1, and is at the same level or even higher than that of Comparative Example 2, which is toughened with conventional MBS. Meanwhile, the heat distortion temperature, flexural modulus, and Rockwell hardness of the Examples are all superior to those of Comparative Example 2, and essentially maintain or exceed the levels of pure PMMA. In terms of optical performance, the transmittance and haze of the Examples are basically consistent with those of pure PMMA, and far superior to those of Comparative Example 2, which suffers from deteriorated optical performance due to phase separation.

[0067] The comparison between Example 1 and Comparative Examples 3 and 4 demonstrates the necessity of the synergistic effect of the Lewis acid center donor and the multifunctional bridging ligand. The properties of Comparative Examples 3 and 4 showed no substantial improvement compared to pure PMMA, indicating that a single component cannot effectively construct a reinforcing network. Only when both components are present can a significant improvement in material properties be achieved through the synergistic effect of ionic coordination and hydrogen bonding.

[0068] Finally, the comparison between Example 1 and Comparative Example 5 clarified the crucial role of competitive displacement agents in regulating processing performance. While Comparative Example 5 exhibited excellent mechanical and thermal properties, its extremely low melt index indicated excessively high melt viscosity and poor processing flowability. Example 1, by adding only 0.2 parts by weight of ethylene bis-stearamide to Comparative Example 5, restored the MFI value to 3.5 g / 10 min, effectively improving flowability while maintaining essentially the same mechanical and thermal properties. This confirms that competitive displacement agents can effectively reduce the melt viscosity of the system during processing without sacrificing the final product's performance.

[0069] In summary, the test data show that by constructing a dynamic and reversible supramolecular network and introducing a competitive substitution mechanism to regulate the network, this invention successfully prepared a polymethyl methacrylate composition with high toughness, high rigidity, high heat resistance, high transparency, and good processing flowability.

Claims

1. A polymethyl methacrylate composition, characterized by, The poly-methyl methacrylate resin is prepared from raw materials comprising the following weight parts: Poly-methyl methacrylate resin: 100 parts; Lewis acid center provider: 0.2-3.2 parts; Multifunctional bridging ligand: 0.2-3.2 parts; Competitive displacement aid: 0.1-1.1 parts.

2. The polymethyl methacrylate composition according to claim 1, characterized by The weight ratio of the Lewis acid center provider to the multifunctional bridging ligand is (1.0-1.5):

1.

3. The polymethyl methacrylate composition according to claim 1, wherein The Lewis acid center provider is at least one selected from zinc stearate, zinc laurate, zinc acetylacetone, magnesium stearate, aluminum stearate, aluminum acetylacetone.

4. The polymethyl methacrylate composition according to claim 1, wherein The multifunctional bridging ligand is at least one selected from melamine, triisocyanuric acid, guanine, urea, dicyandiamide, adipic dihydrazide.

5. The polymethyl methacrylate composition according to claim 1, wherein The competitive displacement aid is at least one selected from ethylene bis-stearamide, erucamide, oleamide, pentaerythritol, glycerol monostearate.

6. A process for the preparation of the polymethyl methacrylate composition according to claims 1 to 5, characterized in that The method comprises the following steps: The poly-methyl methacrylate resin is subjected to drying pretreatment; The Lewis acid center provider, multifunctional bridging ligand, and competitive displacement aid are subjected to drying pretreatment; After the pretreated poly-methyl methacrylate resin, Lewis acid center provider, multifunctional bridging ligand, and competitive displacement aid are mixed, melt blending is performed at a temperature of 210-245°C.

7. The method of polymethyl methacrylate composition according to claim 6, characterized in that, The temperature during drying of the poly-methyl methacrylate resin is 80-95°C, and the time is 3-5 hours; The temperature during drying of the Lewis acid center provider, multifunctional bridging ligand, and competitive displacement aid is 60-80°C, and the time is 1-2 hours.

8. The method of polymethyl methacrylate composition according to claim 6, characterized by, The melt blending step is performed in a twin-screw extruder.

9. The method of polymethyl methacrylate composition according to claim 8, characterized in that, The screw rotation speed of the twin-screw extruder is 250-500 rpm.

10. The method of polymethyl methacrylate composition according to claim 8, characterized in that, The barrel temperature distribution of the twin-screw extruder is: 180-200°C for the feeding section, 225-245°C for the mixing reaction section, and 220-240°C for the head.