Graphene-polylactic acid composite soundproof cotton and preparation method thereof

Abstract

The application relates to the technical field of sound insulation materials, in particular to a graphene-polylactic acid composite sound insulation cotton which is composed of the following raw materials: polylactic acid, graphene, plasticizer, compatilizer and antioxidant; the polylactic acid is levorotatory polylactic acid with a number average molecular weight of 100,000-150,000 or a mixture of levorotatory polylactic acid and racemic polylactic acid; the graphene is graphene oxide or reduced graphene oxide; and the compatilizer is maleic anhydride grafted polylactic acid. The application forms a uniform pore structure by constructing a synergistic mechanism of modified graphene blocking and porous filler adsorption and optimizing the process, greatly improves the sound wave attenuation effect, and obviously improves the sound insulation performance of the existing pure polylactic acid sound insulation cotton and simple composite scheme, so that the sound insulation cotton can meet the noise reduction requirements of multiple scenes such as automobiles, buildings, aerospace, etc.

Description

Technical Field

[0001] This invention relates to the field of sound insulation materials technology, specifically to a graphene-polylactic acid composite sound insulation cotton and its preparation method. Background Technology

[0002] With the increasing demands for sound insulation materials in the automotive, construction, and aerospace industries, sound insulation materials that combine environmental friendliness and high performance have become a hot research topic. Polylactic acid (PLA), as a biodegradable and environmentally friendly polymer, is widely used in the field of sound insulation materials due to its renewable and environmentally friendly nature. However, pure PLA sound insulation cotton has significant performance shortcomings. Its sound insulation effect is limited, making it difficult to meet the noise reduction needs of high-end scenarios. Furthermore, its mechanical strength is insufficient, making it prone to damage during use. Its thermal stability and aging resistance also need improvement, limiting the further expansion of its application range.

[0003] To improve the performance of polylactic acid (PLA) sound insulation cotton, existing technologies attempt to combine graphene with PLA, leveraging graphene's superior physical properties to optimize the material's overall performance. However, existing composite solutions suffer from several technical challenges: some solutions simply add graphene without targeted modification, resulting in poor compatibility between graphene and the PLA matrix, leading to agglomeration and hindering the full realization of its performance advantages; some solutions suffer from imbalanced component dosages, with unreasonable graphene additions causing a decline in material performance; and other solutions fail to achieve synergistic optimization of components and processes, simply combining existing technologies, causing mutual constraints on material properties and hindering synergistic effects. Furthermore, in some solutions, inappropriate selection of the PLA matrix's molecular weight and configuration, or unreasonable combination of auxiliary components, further exacerbates the imbalance between mechanical and processing properties, increasing the difficulty of industrial application. These problems limit the performance improvement of existing graphene-PLA composite sound insulation materials, failing to meet the market's urgent demand for high-performance, environmentally friendly sound insulation materials. Therefore, a technical solution that can overcome these shortcomings is urgently needed. Summary of the Invention

[0004] The primary objective of this invention is to provide a graphene-polylactic acid composite sound insulation cotton and its preparation method.

[0005] A further objective of this invention is to provide a graphene-polylactic acid composite sound insulation cotton, which, by weight, is composed of the following raw materials: 100 parts polylactic acid, 1-3 parts graphene, 4-6 parts plasticizer, 2-3 parts compatibilizer, and 0.4-0.8 parts antioxidant; wherein the polylactic acid is L-polylactic acid with a number average molecular weight of 100,000 to 150,000 or a mixture of L-polylactic acid and racemic polylactic acid; the graphene is graphene oxide or reduced graphene oxide; and the compatibilizer is maleic anhydride-grafted polylactic acid.

[0006] Preferably, by weight, the raw material further includes 7-9 parts of porous filler, wherein the porous filler is diatomaceous earth with a particle size of 500 mesh.

[0007] Preferably, the mass ratio of L-polylactic acid to racemic polylactic acid is 7:3.

[0008] Preferably, the reduced graphene oxide is modified with a silane coupling agent, wherein the silane coupling agent is KH550, and the amount of the silane coupling agent is 5% of the mass of the reduced graphene oxide.

[0009] Preferably, the plasticizer is tributyl citrate, or a mixture of tributyl citrate and polyethylene glycol, wherein the mass ratio of tributyl citrate to polyethylene glycol is 6:4.

[0010] Preferably, the antioxidant is antioxidant 1010, or a mixture of antioxidant 1010 and antioxidant 168, wherein the mass ratio of antioxidant 1010 to antioxidant 168 is 1:1.

[0011] A method for preparing the graphene-polylactic acid composite sound insulation cotton includes the following steps: raw material pretreatment, melt blending, molding and granulation, foaming molding, and compression molding; the melt blending involves first mixing polylactic acid, plasticizer, compatibilizer, and antioxidant, and then adding graphene for further blending; the foaming molding is carried out at a temperature of 190°C to 200°C and a pressure of 1.5 MPa to 1.8 MPa; the compression molding is carried out at a temperature of 160°C to 170°C and a pressure of 2 MPa to 2.5 MPa.

[0012] Preferably, in the raw material pretreatment, polylactic acid is dried in a vacuum drying oven at 80°C for 4 hours; graphene is dried in a vacuum drying oven at 60°C for 6 hours; if the raw material contains porous filler, the porous filler is pretreated by drying at 100°C for 4 hours.

[0013] Preferably, the melt blending temperature is 180°C to 190°C, the screw speed is 300 r / min to 350 r / min, and the blending time after adding graphene is 8 minutes to 10 minutes.

[0014] Preferably, the cooling rate of the molding and granulation is 10°C / min to 25°C / min; the foaming molding time is 8 minutes to 10 minutes; and the pressing molding time is 5 minutes to 6 minutes.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention constructs a synergistic mechanism of modified graphene barrier and porous filler adsorption, and combines process optimization to form a uniform foam structure, which greatly improves the sound wave attenuation effect. The sound insulation performance is significantly improved compared with existing pure polylactic acid sound insulation cotton and simple composite solutions, and can meet the noise reduction needs of multiple scenarios such as automobiles, buildings, and aerospace.

[0016] 2. This invention achieves a significant improvement in tensile strength and elongation at break by precisely matching the molecular weight and configuration of polylactic acid substrate with the enhanced interfacial bonding effect of modified graphene. The material possesses excellent structural strength and toughness, effectively solving the problem of imbalance between mechanical properties and processing performance in existing technologies, and meeting the strength requirements for practical applications.

[0017] 3. The present invention adopts a synergistic design of compound antioxidants and composite plasticizers, which significantly improves the thermal decomposition temperature and tensile strength retention rate after aging of the material, extends the service life of the product, and broadens its application scenarios in different temperature environments.

[0018] 4. While improving various performance aspects, this invention effectively reduces material density, breaking the limitation that sound insulation performance improvement is often accompanied by increased density in existing technologies. This is more in line with the current trend of lightweight applications and further enhances the application value of the product.

[0019] 5. Furthermore, the technical solution of the present invention does not rely on complex process equipment, the raw material ratio is scientific and reasonable, the components and process system are well compatible, and industrial production can be achieved without significant adjustments to the existing production process, thereby reducing production costs and having broad market application prospects. Detailed Implementation

[0020] 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.

[0021] Example 1: This embodiment serves as the foundation of the entire technical system. Its core objective is to achieve the effective composite of graphene and polylactic acid, initially improving the performance shortcomings of pure polylactic acid sound insulation cotton, and providing a stable core composite matrix for subsequent optimization in various dimensions.

[0022] The raw material formula by weight is as follows: 100 parts polylactic acid (PLA), number average molecular weight 100,000, L-PLA; 2 parts graphene, graphene oxide, unmodified; 5 parts plasticizer, tributyl citrate; 2 parts compatibilizer, maleic anhydride-grafted PLA; 0.5 parts antioxidant, antioxidant 1010.

[0023] Preparation steps: Raw material pretreatment: Polylactic acid was dried in an 80℃ vacuum drying oven for 4 hours to remove moisture, and graphene oxide was dried in a 60℃ vacuum drying oven for 6 hours for later use; Melt blending: The dried polylactic acid, plasticizer, compatibilizer, and antioxidant were added to a twin-screw extruder and melt blended for 5 minutes at 80℃-180℃ and a screw speed of 300 r / min. Then, graphene oxide was added and blended for another 8 minutes to obtain a blend; Molding and granulation: The blend was extruded through the extruder die head and granulated after cooling at a cooling rate of 10℃ / min to obtain composite granules; Foaming and molding: The composite granules were added to a foaming machine and foamed for 10 minutes at 190℃ and a pressure of 1.5 MPa. Then, they were pressed and molded at 160℃ and a pressure of 2 MPa for 5 minutes. After cooling to room temperature, graphene-polylactic acid composite sound insulation cotton was obtained.

[0024] Example 2: The raw material formula, by weight, is the same as in Example 1, except that the graphene-related parameters are adjusted: 2 parts graphene, reduced graphene oxide, modified with silane coupling agent KH550, the amount of coupling agent is 5% of the graphene mass, the modification temperature is 80℃, and the modification time is 2h.

[0025] Preparation steps: completely consistent with Example 1, without adjusting process parameters. The core verification is the compatibility of modified graphene with existing basic processes, ensuring that the modification scheme can be implemented without relying on complex processes.

[0026] Example 3: The raw material formula, by weight, is the same as in Example 2, except that the parameters related to polylactic acid are adjusted: 100 parts of polylactic acid with a number average molecular weight of 150,000, and L-polylactic acid and racemic polylactic acid are mixed at a weight ratio of 7:3.

[0027] Preparation steps: completely consistent with Example 2. By optimizing the substrate ratio to adapt to the existing process system, performance upgrades can be achieved without adjusting process parameters, reducing the cost of industrial applications.

[0028] Example 4: The raw material formula, by weight, is the same as in Example 3, except that the types and amounts of auxiliary components are adjusted: 8 parts of porous filler, diatomaceous earth, 500 mesh particle size, pretreated by drying at 100 degrees Celsius for 4 hours; 6 parts of plasticizer, tributyl citrate; 3 parts of compatibilizer, maleic anhydride grafted polylactic acid.

[0029] Preparation steps: completely consistent with Example 3, ensuring the compatibility of porous packing with the existing process system, without the need for significant adjustments to process parameters, thus ensuring the continuity and operability of the technology.

[0030] Example 5: Raw material formulation: It is completely consistent with Example 4. The core is to improve performance by optimizing process parameters. There is no need to adjust the raw material ratio, which reduces the complexity of the formulation and the cost of industrialization.

[0031] The preparation steps were the same as in Example 4, except for the process parameters: melt blending temperature 190℃, screw speed 350r / min, blending time after adding graphene 10min; cooling rate 25℃ / min; foaming molding temperature 200℃, pressure 1.8MPa, foaming time 8min; pressing molding temperature 170℃, pressure 2.5MPa, time 6min.

[0032] Example 6: The raw material formula, by weight, is the same as in Example 5, except that the parameters of plasticizer and antioxidant are adjusted: 4 parts plasticizer, tributyl citrate and polyethylene glycol are mixed at a weight ratio of 6:4; 0.8 parts antioxidant, antioxidant 1010 and antioxidant 168 are compounded at a weight ratio of 1:1.

[0033] Preparation steps: completely consistent with Example 5, ensuring that the optimized auxiliary components are perfectly compatible with the existing process system, and guaranteeing the industrial feasibility of the final solution.

[0034] Comparative Example 1: This scheme is a typical preparation method for pure polylactic acid sound insulation cotton in the existing technology. It does not add graphene and represents the current technical level of polylactic acid sound insulation materials without graphene modification. Its core defects are poor sound insulation performance, low mechanical strength and insufficient temperature resistance.

[0035] The raw material formula by weight is as follows: 100 parts polylactic acid (PLA), number average molecular weight 100,000, L-PLA; 5 parts plasticizer, tributyl citrate; 2 parts compatibilizer, maleic anhydride-grafted PLA; 50.5 parts antioxidant, antioxidant 1010.

[0036] Preparation steps: Same as in Example 1, except that no graphene was added.

[0037] Comparative Example 2: This approach is a typical example of simply adding graphene to polylactic acid in existing technologies. It does not involve any specific modification of the graphene and represents the current level of technology for simple composite of graphene and polylactic acid. It is also a common way to combine existing technologies simply. Its core drawback is poor compatibility, easy agglomeration, and limited performance improvement.

[0038] The raw material formula, by weight, is the same as in Example 2, except that the graphene-related parameters are adjusted: 2 parts graphene, reduced graphene oxide, without any modification.

[0039] Preparation steps: Same as in Example 2.

[0040] Comparative Example 3: This scheme references a typical design in the prior art where the amount of graphene added is improperly controlled, which is beyond the scope of protection of this invention. It represents a common defect in the prior art where the amount of components is mismatched, and it is also a problem that is easy to occur when the prior art is simply combined. The core defect is that excessive amount leads to a decrease in aggregation performance.

[0041] The raw material formula, by weight, is the same as in Example 2, except for the amount of graphene added: 12 parts graphene, reduced graphene oxide, modified by silane coupling agent KH550.

[0042] Preparation steps: Same as in Example 2.

[0043] Comparative Example 4: This design, referencing a typical design in the prior art where the molecular weight of polylactic acid was improperly selected, exceeds the scope of protection of this invention. It represents a technical shortcoming of insufficient compatibility between existing polylactic acid substrates and graphene composite systems, and is also a common defect of simple combinations in existing technologies. The core defect is the imbalance between mechanical properties and processing performance.

[0044] The raw material formula, by weight, is the same as in Example 3, except that the polylactic acid parameters are adjusted: 100 parts polylactic acid with a number average molecular weight of 350,000, and L-polylactic acid and racemic polylactic acid are mixed at a weight ratio of 7:3.

[0045] Preparation steps: Same as in Example 3.

[0046] Comparative Example 5: This solution is a simple superposition of existing graphene composite technology, polylactic acid molding technology, and porous material preparation technology. It does not perform synergistic optimization of composition and process, and represents the typical level of simple combination of existing technologies. It is also the key technical pain point that this invention focuses on breaking through. The core defect is poor compatibility of composition and process, mutual restriction of performance, and inability to synergistically enhance efficiency.

[0047] Raw material formulation: Same as in Example 4, except that porous filler was not added.

[0048] The preparation steps were the same as in Example 4, except that the foaming parameters were adjusted: foaming temperature 240℃, pressure 0.3MPa, and foaming time 15min.

[0049] The modification operation of reduced graphene oxide with silane coupling agent KH550 in this invention is as follows: Reduced graphene oxide is mixed with deionized water to form a dispersion, and 5% of the mass of reduced graphene oxide KH550 silane coupling agent is added. The mixture is stirred and reacted at 80°C for 2 hours. After the reaction is completed, the mixture is filtered, dried, and ground to obtain modified reduced graphene oxide. This modification operation does not require special equipment and can be achieved by those skilled in the art through conventional wet modification processes.

[0050] The mass ratio range of each raw material in this invention is derived from the specific ratio optimization of Examples 1-6. The ratio range of 1-3 parts graphene and 7-9 parts porous filler can avoid the problem of decreased material mechanical properties caused by graphene agglomeration and excessive porous filler. The ratio range of 4-6 parts plasticizer, 2-3 parts compatibilizer and 0.4-0.8 parts antioxidant can achieve synergistic optimization of polylactic acid processing performance, compatibility and thermal stability. Those skilled in the art can adjust the specific amount of each raw material within this ratio range to prepare composite sound insulation cotton with excellent sound insulation, mechanical and thermal stability without making significant adjustments to the preparation process parameters described in this invention.

[0051] The maleic anhydride-grafted polylactic acid used in this invention is a conventional modified polylactic acid product in the field of polymer composites. Its maleic anhydride grafting rate is 0.5%-2.0%. Maleic anhydride-grafted polylactic acid within this grafting rate range can effectively improve the interfacial bonding force between the polylactic acid matrix and graphene and inhibit the aggregation of graphene in the matrix. Those skilled in the art can select one from this range according to actual production needs, and all can achieve the technical effects of this invention.

[0052] The equipment used in this invention are all conventional equipment in the field of polymer material molding, including twin-screw extruders, foaming machines, flat vulcanizing machines (for compression molding), vacuum drying ovens, etc. There are no special limitations on the model and specifications of the equipment. Those skilled in the art can choose one according to the production scale. The operating parameters of conventional equipment can be adapted to the process conditions described in this invention. The equipment used in the preparation process of this invention are all conventional and general-purpose equipment in the field of polymer material molding, specifically including twin-screw extruders, foaming machines, flat vulcanizing machines (for compression molding), vacuum drying ovens, etc. There are no special limitations on the model and specifications of the equipment. Those skilled in the art can choose one according to the production scale. The conventional operating parameters of conventional equipment can be adapted to the process conditions described in this invention, without the need for additional equipment modification.

[0053] Test sample: The graphene-polylactic acid composite sound insulation cotton or pure polylactic acid sound insulation cotton prepared in Examples 1 to 6 and Comparative Examples 1 to 5 of this invention were all cut into standard sample sizes of 100mm×100mm×20mm. Each group of samples was tested in parallel three times, and the average value was taken as the test result. The test process strictly followed the relevant national standards to ensure the accuracy, reliability and repeatability of the test data, and to provide strong data support for the feasibility of the technical solution.

[0054] The test items, standards, and instruments are listed in Table 1 below:

[0055] The test results are shown in Table 2 below:

[0056] Test Result Analysis: The above test results clearly demonstrate the performance differences between the various embodiments of the present invention and related prior art solutions. The performance indicators of each embodiment show a trend of gradual optimization, and the overall performance is significantly better than the prior art and simple combinations of technologies represented by the comparative examples. The testing process was strictly carried out in accordance with national standards, and the sample preparation and testing operations were repeatable. The test data are authentic and reliable, fully demonstrating the feasibility and rationality of the technical solution of the present invention and ensuring its stable implementation.

[0057] In terms of sound insulation performance, the average sound insulation of Examples 5 and 6 reached 42.3 dB and 41.8 dB, respectively, which is more than 65% higher than that of Comparative Example 1 and more than 30% higher than that of Comparative Example 5. This performance improvement is due to the synergistic mechanism of modified graphene barrier and porous filler adsorption constructed in this invention, combined with the uniform pore structure formed by process optimization, which effectively improves the sound wave attenuation effect. Compared with the existing technology and simple combination schemes, the sound insulation performance is significantly optimized, which can meet the sound insulation requirements of scenarios such as automobiles, buildings, and aerospace.

[0058] In terms of mechanical properties, Example 6 exhibits a tensile strength of 27.5 MPa and an elongation at break of 22.5%, representing improvements of over 115% compared to Comparative Example 1 and over 70% and 70% / 78% respectively compared to Comparative Example 3. This optimization is attributed to the precise matching of the molecular weight and configuration of the polylactic acid substrate, as well as the enhancing effect of modified graphene on interfacial bonding. This effectively solves the problem of imbalance between mechanical and processing properties in existing technologies, giving the composite sound insulation cotton good structural strength and toughness, meeting the needs of practical applications.

[0059] Regarding thermal stability and aging resistance, Example 6 exhibited a thermal decomposition temperature of 315°C and a tensile strength retention rate of 92.3% after aging, representing improvements of over 21.9% and 21.2% respectively compared to Comparative Example 1, and over 13% and 17.1% respectively compared to Comparative Example 2. This advantage stems from the synergistic effect of the compounded antioxidant and composite plasticizer. Through targeted component optimization, the thermal stability and environmental aging resistance of the composite system were enhanced, extending the product's service life and broadening its application scenarios.

[0060] In terms of lightweight performance, the density of Example 6 is only 0.25 g / cm³. 3 Compared to Comparative Example 1, the density is reduced by 28.6%, and compared to Comparative Example 5, the density is reduced by 26.5%. This invention achieves simultaneous optimization of lightweighting while improving sound insulation and mechanical properties, breaking the limitation of existing technologies where improved sound insulation performance is often accompanied by increased density. This makes the product more suitable for lightweight applications and further enhances the product's application value.

[0061] In summary, this invention forms a complete technical system through multi-dimensional design involving graphene modification, polylactic acid substrate optimization, synergistic use of functional auxiliary components, and precise control of process parameters. The raw material ratios in each embodiment are clearly defined, the process steps are detailed, and the test data fully verify the superiority and feasibility of the technical solution. Each aspect of the technical solution has been reasonably verified, the parameter settings are scientifically sound, and it can stably achieve industrial production, providing high-performance, environmentally friendly composite sound insulation materials for related fields.

[0062] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A graphene-polylactic acid composite sound insulation cotton, characterized in that, The product is composed of the following raw materials by weight: 100 parts polylactic acid, 1-3 parts graphene, 4-6 parts plasticizer, 2-3 parts compatibilizer, and 0.4-0.8 parts antioxidant; wherein the polylactic acid is L-polylactic acid with a number average molecular weight of 100,000 to 150,000 or a mixture of L-polylactic acid and racemic polylactic acid; wherein the graphene is graphene oxide or reduced graphene oxide; and wherein the compatibilizer is maleic anhydride-grafted polylactic acid.

2. The graphene-polylactic acid composite sound insulation cotton according to claim 1, characterized in that, The raw materials also include 7-9 parts of porous filler by weight, wherein the porous filler is diatomaceous earth with a particle size of 500 mesh.

3. The graphene-polylactic acid composite sound insulation cotton according to claim 1, characterized in that, The mass ratio of L-polylactic acid to racemic polylactic acid is 7:

3.

4. The graphene-polylactic acid composite sound insulation cotton according to claim 1, characterized in that, The reduced graphene oxide is modified with a silane coupling agent, the silane coupling agent being KH550, and the amount of the silane coupling agent being 5% of the mass of the reduced graphene oxide.

5. The graphene-polylactic acid composite sound insulation cotton according to claim 1, characterized in that, The plasticizer is tributyl citrate, or a mixture of tributyl citrate and polyethylene glycol, wherein the mass ratio of tributyl citrate to polyethylene glycol is 6:

4.

6. The graphene-polylactic acid composite sound insulation cotton according to claim 1, characterized in that, The antioxidant is antioxidant 1010, or a mixture of antioxidant 1010 and antioxidant 168, wherein the mass ratio of antioxidant 1010 to antioxidant 168 is 1:

1.

7. A method for preparing graphene-polylactic acid composite sound insulation cotton as described in any one of claims 1 to 6, characterized in that, Includes the following steps: The process includes raw material pretreatment, melt blending, molding and granulation, foaming molding, and compression molding. The melt blending involves first mixing polylactic acid, plasticizer, compatibilizer, and antioxidant, and then adding graphene for further blending. The foaming molding is carried out at a temperature of 190°C to 200°C and a pressure of 1.5MPa to 1.8MPa. The compression molding is carried out at a temperature of 160°C to 170°C and a pressure of 2MPa to 2.5MPa.

8. The preparation method according to claim 7, characterized in that, In the raw material pretreatment, polylactic acid is dried in a vacuum drying oven at 80°C for 4 hours; graphene is dried in a vacuum drying oven at 60°C for 6 hours; if the raw material contains porous filler, the porous filler is pretreated by drying at 100°C for 4 hours.

9. The preparation method according to claim 7, characterized in that, The melt blending temperature is 180°C to 190°C, the screw speed is 300 r / min to 350 r / min, and the blending time after adding graphene is 8 minutes to 10 minutes.

10. The preparation method according to claim 7, characterized in that, The cooling rate for the granulation process is 10°C / min to 25°C / min; the foaming time is 8 to 10 minutes; and the pressing time is 5 to 6 minutes.

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