Highly transparent hydrolysis-resistant nylon composite material and preparation method thereof

Abstract

The application discloses a kind of high transparent hydrolysis-resistant nylon composite material and preparation method thereof.The composite material comprises, by weight parts: transparent nylon resin 100 parts, carbodiimide hydrolysis stabilizer 0.3-1.2 parts, epoxy functionalized cage-type silsesquioxane 0.5-1.5 parts, composite antioxidant 0.2-0.5 parts, lubricant 0.1-0.3 parts;It is prepared by the process of high-speed mixing, double-screw extrusion granulation, post-processing, and the core constructs polymeric polycarbodiimide capping+epoxy POSS dynamic crosslinking dual-protection mechanism.The application significantly improves the hydrolysis resistance of the nylon material without sacrificing its transparency, with a tensile strength retention rate of ≥85% after 48 hours of boiling at 121°C, and the dynamic crosslinking network formed by epoxy POSS is reversible, with a tensile strength retention rate of ≥90% after three times of recycling.The application can be applied to harsh use scenarios such as medical devices, optical devices and automotive window materials.

Description

Technical Field

[0001] This invention belongs to the field of polymer material modification technology, specifically relating to a recyclable, highly transparent, hydrolysis-resistant nylon composite material and its preparation method. Background Technology

[0002] Transparent nylon, as an important category of high-end transparent polymer materials, has broad application prospects in medical devices, optical components, and other fields due to its excellent transparency, chemical resistance, and mechanical properties. However, transparent nylon is prone to hydrolytic degradation in high-temperature and high-humidity environments, leading to problems such as turbidity and a sharp drop in mechanical properties, which severely limits its application in harsh working conditions.

[0003] Existing technologies for modifying the hydrolysis resistance of transparent nylon have several drawbacks: First, while copolymerization modification, such as PA12, can slightly improve hydrolysis resistance, the modification cost is high and the effect is limited, failing to meet the requirements for long-term use under humid and hot conditions. Second, simply adding polymeric polycarbodiimide hydrolysis stabilizers can only inhibit hydrolysis autocatalysis by capping carboxyl groups; excessive addition will damage the transparency of the material, and the protective effect under long-term high temperature and high humidity is insufficient. Third, in-situ polymerization methods that introduce nanofillers to construct cross-linked structures are complex processes with high equipment requirements, and the resulting cross-linked structures are irreversible, making the material unrecyclable and inconsistent with the requirements of circular economy development. Fourth, existing nanofiller modification routes, such as layered silicate modification, are prone to nanoparticle agglomeration, severely reducing the transparency of the material, and irreversible cross-linking leads to significant performance degradation after recycling.

[0004] In summary, existing technologies cannot simultaneously meet the triple requirements of high transparency, excellent hydrolysis resistance, and recyclability of transparent nylon materials. Furthermore, some modification technologies are complex and costly to produce, making industrial-scale promotion difficult. These issues have become urgent technical challenges to be addressed in this field. Summary of the Invention

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A highly transparent hydrolysis-resistant nylon composite material comprises the following raw material components by weight: 100 parts transparent nylon resin; 0.3-1.2 parts carbodiimide hydrolysis stabilizer; 0.5-1.5 parts epoxy functionalized cage-like silsesquioxane; 0.2-0.5 parts composite antioxidant; and 0.1-0.3 parts lubricant. The dynamic crosslinking network formed by the epoxy functionalized cage-like silsesquioxane and the nylon end groups can dissociate at the processing temperature and re-crosslink at room temperature.

[0006] Preferably, the transparent nylon resin is selected from one or more of semi-aromatic transparent nylon and alicyclic transparent nylon, and the glass transition temperature Tg of the nylon resin is ≥120℃ and the visible light transmittance is ≥90%.

[0007] Preferably, the carbodiimide hydrolytic stabilizer is a polymeric polycarbodiimide with a melting point of 70-90℃ and a decomposition temperature of ≥130℃.

[0008] Furthermore, the epoxy equivalent of the epoxy-functionalized cage-type silsesquioxane is 150-250 g / mol, preferably epoxy cyclohexyl-functionalized cage-type silsesquioxane; the dual hydrolysis-resistant protection mechanism of polymeric polycarbodiimide carboxyl end-capping and epoxy POSS dynamic crosslinking, together with the other two, ensures that the tensile strength retention rate is ≥85% after cooking at 121°C for 48 hours.

[0009] Furthermore, the composite antioxidant is a compound system of hindered phenolic antioxidant and phosphite auxiliary antioxidant in a mass ratio of 2:1; the hindered phenolic antioxidant is Irganox 1098, and the phosphite auxiliary antioxidant is Irgafos 168.

[0010] Preferably, the lubricant is selected from one or more combinations of ethylene bis-stearamide and high molecular weight silicone powder.

[0011] A method for preparing a highly transparent, hydrolysis-resistant nylon composite material includes the following steps: S1. Raw material mixing: Add transparent nylon resin, carbodiimide hydrolytic stabilizer, epoxy functionalized cage-type silsesquioxane, composite antioxidant and lubricant to a high-speed mixer according to the weight ratio, mix for 3 to 8 minutes to obtain the mixture. S2. Twin-screw extrusion granulation: The mixture is fed into a twin-screw extruder with a length-to-diameter ratio of 40:1. The temperatures of each zone of the extruder from the feed port to the die head are as follows: Zone 1 220℃, Zone 2 260℃, Zone 3 260℃, Zone 4 260℃, Zone 5 240℃, Zone 6 240℃, Zone 7 230℃, Zone 8 230℃, Zone 9 240℃, Zone 10 250℃, and Die head 260℃. The screw speed is 300 rpm, the vacuum degree is -0.09 MPa, and the entire process is vacuum exhaust. After the molten material is extruded through the die head, it enters a 30℃ water cooling tank for cooling. S3. Post-processing: The cooled extrudate is air-dried and pelletized to obtain granules; the granules are vacuum-dried at 80-100℃ for 3-4 hours to obtain recyclable, highly transparent, hydrolysis-resistant nylon composite material.

[0012] Furthermore, it also includes a recyclability verification step: the composite material granules obtained in step S3 are processed three times in the same manner as steps S2-S3, and the mechanical properties and transparency retention rate of the material are tested after each recycling.

[0013] The beneficial effects of this invention are: 1. Excellent hydrolysis resistance: Through the dual protection mechanism of polymeric polycarbodiimide end capping + epoxy POSS dynamic crosslinking, the hydrolysis resistance is synergistically enhanced. After being boiled at 121℃ for 48 hours, the tensile strength retention rate of the material increases from ≤50% to over 85%, and the material remains transparent without whitening. 2. Good transparency: Both carbodiimide hydrolytic stabilizer and epoxy POSS are added in low amounts, with a total amount not exceeding 2.7 parts. Epoxy POSS is dispersed at the nanoscale molecular level and does not cause visible light scattering. The visible light transmittance of the composite material is ≥88%, and the haze is ≤3%, which meets the requirements of optical applications. 3. Excellent recyclability: The dynamic cross-linked network formed by epoxy POSS and nylon end groups can be reversibly dissociated at the processing temperature. The material can be melt-processed multiple times without irreversible cross-linking or gelation. After three recyclings, the tensile strength retention rate is ≥90%, which meets the requirements of circular economy development.

[0014] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below. Detailed Implementation

[0015] The preferred embodiments of the present invention will be described in detail below so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more explicit definition of the scope of protection of the present invention.

[0016] This invention provides a recyclable, highly transparent, hydrolysis-resistant nylon composite material, comprising the following raw material components by weight: 100 parts transparent nylon resin; 0.3-1.2 parts carbodiimide hydrolysis stabilizer; 0.5-1.5 parts epoxy functionalized cage-type silsesquioxane (epoxy POSS); 0.2-0.5 parts composite antioxidant; and 0.1-0.3 parts lubricant.

[0017] Preferably, the transparent nylon resin is selected from one or a mixture of semi-aromatic transparent nylon, alicyclic transparent nylon, and has a glass transition temperature (Tg) ≥ 120℃ and visible light transmittance ≥ 90%, ensuring the transparency and heat resistance of the material base. The carbodiimide hydrolysis stabilizer is a polymeric polycarbodiimide with a melting point of 70-90℃, which can react with the nylon terminal carboxyl groups and the carboxyl groups generated by hydrolysis to form a stable acylurea structure, interrupting the hydrolysis chain reaction. The epoxy POSS has an epoxy equivalent of 150-250 g / mol, preferably epoxy cyclohexyl functionalized POSS; its epoxy groups can react with the nylon terminal groups to form high-temperature reversible and room-temperature stable micro-dynamic crosslinking points, which enhances hydrolysis resistance and imparts recyclability to the material.

[0018] Preferably, the composite antioxidant is a mixture of hindered phenolic antioxidant Irganox 1098 and phosphite-based auxiliary antioxidant Irgafos 168, with a mass ratio of 2:1, which can effectively inhibit thermo-oxidative aging during material processing and use. The lubricant is selected from ethylene bis-stearamide (EBS) and high molecular weight silicone powder, which improves the material's processing fluidity and avoids problems such as sticking to the mold and uneven plasticization during extrusion.

[0019] Furthermore, the preparation method of the high-transparency hydrolysis-resistant nylon composite material of the present invention includes the following steps: S1. Raw material mixing: Add transparent nylon resin, carbodiimide hydrolytic stabilizer, epoxy functionalized cage-type silsesquioxane, composite antioxidant and lubricant to a high-speed mixer according to the weight ratio, mix for 3 to 8 minutes to obtain the mixture. S2. Twin-screw extrusion granulation: The mixture is fed into a twin-screw extruder with a length-to-diameter ratio of 40:1. The temperatures of each zone of the extruder from the feed port to the die head are as follows: Zone 1 220℃, Zone 2 260℃, Zone 3 260℃, Zone 4 260℃, Zone 5 240℃, Zone 6 240℃, Zone 7 230℃, Zone 8 230℃, Zone 9 240℃, Zone 10 250℃, and Die head 260℃. The screw speed is 300 rpm, the vacuum degree is -0.09 MPa, and the entire process is vacuum exhaust. After the molten material is extruded through the die head, it enters a 30℃ water cooling tank for cooling. S3. Post-processing: The cooled extrudate is air-dried and pelletized to obtain granules; the granules are vacuum-dried at 80-100℃ for 3-4 hours to obtain recyclable, highly transparent, hydrolysis-resistant nylon composite material.

[0020] S4. Recyclability verification step: Repeat the process of steps S2-S3 three times with the composite material granules obtained in step S3, and test the mechanical properties and transparency retention rate of the material after each recycling.

[0021] Raw material information The raw materials used in the following examples and comparative examples are: transparent nylon PA MACM12 with a glass transition temperature Tg = 155℃ and visible light transmittance of 92%; transparent nylon PA 6I / 6T copolymer with a glass transition temperature Tg = 125℃ and visible light transmittance of 90%; polymeric polycarbodiimide with a melting point of 70-90℃; epoxy POSS with an epoxy equivalent of approximately 180 g / mol, which is epoxy cyclohexyl functionalized; the composite antioxidant is a mixture of Irganox 1098 and Irgafos 168 in a mass ratio of 2:1; the lubricant is ethylene bis-stearamide (EBS); and layered silicate nanosheets, surface-functionalized, were used as raw materials for comparative experiments. All examples and comparative examples followed the same preparation steps as described above, and will not be described further below.

[0022] Example 1: The recyclable, highly transparent, hydrolysis-resistant nylon composite material of this embodiment has the following raw material components by weight: 100 parts transparent nylon PA MACM12, 0.8 parts polymeric polycarbodiimide, 1.5 parts epoxy POSS, 0.4 parts composite antioxidant, and 0.2 parts EBS.

[0023] Example 2: The recyclable, highly transparent, hydrolysis-resistant nylon composite material of this embodiment has the following raw material components by weight: 100 parts of transparent nylon PA MACM12, 1.2 parts of polymeric polycarbodiimide, 1.0 part of epoxy POSS, 0.4 parts of composite antioxidant, and 0.2 parts of EBS.

[0024] Example 3: The recyclable, highly transparent, hydrolysis-resistant nylon composite material of this embodiment has the following raw material components by weight: 100 parts of transparent nylon PA 6I / 6T copolymer, 0.8 parts of polymeric polycarbodiimide, 1.5 parts of epoxy POSS, 0.4 parts of composite antioxidant, and 0.2 parts of EBS.

[0025] Comparative Example 1: This comparative example is an unmodified transparent nylon material. The raw material composition by weight is: 100 parts transparent nylon PAMACM12, 0.4 parts composite antioxidant, 0.2 parts EBS, without the addition of polymeric polycarbodiimide and epoxy POSS.

[0026] Comparative Example 2: This comparative example only added polymeric polycarbodiimide as a hydrolysis stabilizer. The raw material composition by weight is: 100 parts transparent nylon PA MACM12, 0.8 parts polymeric polycarbodiimide, 0.4 parts composite antioxidant, and 0.2 parts EBS. No epoxy POSS was added.

[0027] Comparative Example 3: This comparative example only added epoxy POSS as a modifying component. The raw material components by weight are: 100 parts transparent nylon PAMACM12, 1.5 parts epoxy POSS, 0.4 parts composite antioxidant, and 0.2 parts EBS. No polymeric polycarbodiimide was added.

[0028] Comparative Example 4: This comparative example simulates existing nanofiller modification routes and adopts an irreversible crosslinking modification method. The raw material components by weight are: 100 parts of transparent nylon PA MACM12, 0.4 parts of composite antioxidant, 0.2 parts of EBS, and 2 parts of surface-functionalized layered silicate nanosheets. Polymerized polycarbodiimide and epoxy POSS were not added.

[0029] Performance testing The composite materials obtained in Examples 1-3 and Comparative Examples 1-4 were subjected to performance tests. All test standards were kept consistent, and all test data were the average of three parallel tests to ensure the accuracy and comparability of the test results.

[0030] The test items and corresponding test standards are as follows: 1. Light transmittance: Tested according to ISO13468-1 standard, the test sample is a square piece of 50mm×50mm×1mm; 2. Haze: Tested according to ISO14782 standard, the test sample is a square piece of 50mm×50mm×1mm; 3. Tensile strength: Tested according to ISO527-2 standard, the initial tensile strength of the material, the tensile strength after cooking at 121℃ for 48 hours, and the tensile strength after three recyclings are tested respectively, and the corresponding strength retention rate is calculated based on the test results.

[0031] The results are as follows:

[0032] The table above shows that: 1. Synergistic effect of dual protection: Comparing Example 1 with Comparative Examples 2 and 3, it can be seen that Comparative Example 2, which added polymeric polycarbodiimide alone, had a strength retention rate of only 75.4% after cooking, and Comparative Example 3, which added epoxy POSS alone, had a strength retention rate of only 66.2% after cooking. However, Example 1, which added both, had a strength retention rate of 87.7% after cooking, which was significantly higher than that of the comparative examples with single additions. This proves that the end-capping effect of polymeric polycarbodiimide and the dynamic cross-linking effect of epoxy POSS combine to form a significant synergistic effect of hydrolysis resistance.

[0033] 2. Maintaining Transparency Advantage: The transmittance of Examples 1-3 were 90.2%, 89.8%, and 88.5%, respectively, which is close to the 92.1% of the unmodified Comparative Example 1. However, the transmittance of Comparative Example 4, which added layered silicate nanosheets, was only 82.3%, which is much lower than that of the other examples. This shows that the nanoscale molecular dispersion characteristics of epoxy POSS can effectively avoid the problem of nanoparticle aggregation and ensure that the transparency of the material does not decrease significantly.

[0034] 3. Recyclability verification: The tensile strength retention rate of Example 1 after three recyclings reached 93.2%, and that of Examples 2 and 3 was also above 90%. However, the tensile strength retention rate of Comparative Example 4, which adopted irreversible crosslinking modification, was only 74.4% after three recyclings, and the material properties deteriorated severely. This proves that the dynamic crosslinking network constructed in this invention has good reversibility and can realize the multiple recycling of materials.

[0035] 4. Overall performance comparison: Although Comparative Example 4 has an initial tensile strength of 82 MPa, which is higher than that of the other examples, the material has poor transparency, a haze of up to 7.8%, and its performance drops significantly after recycling, resulting in poor overall performance. In contrast, the embodiments of the present invention achieve excellent hydrolysis resistance and good recyclability while maintaining high transparency. Compared with existing modification routes, the overall performance of the material is significantly improved.

[0036] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the present invention specification and content, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A highly transparent, hydrolysis-resistant nylon composite material, characterized in that, The raw material components are as follows by weight: 100 parts transparent nylon resin; 0.3 to 1.2 parts carbodiimide hydrolytic stabilizer; 0.5 to 1.5 parts epoxy functionalized cage-like silsesquioxane; 0.2 to 0.5 parts composite antioxidant; and 0.1 to 0.3 parts lubricant. The dynamic crosslinking network formed by the epoxy functionalized cage-like silsesquioxane and the nylon end groups can dissociate at the processing temperature and re-crosslink at room temperature.

2. The high-transparency, hydrolysis-resistant nylon composite material according to claim 1, characterized in that: The transparent nylon resin is selected from one or more of semi-aromatic transparent nylon and alicyclic transparent nylon, and the glass transition temperature Tg of the nylon resin is ≥120℃ and the visible light transmittance is ≥90%.

3. The high-transparency, hydrolysis-resistant nylon composite material according to claim 1, characterized in that: The carbodiimide hydrolytic stabilizer is a polymeric polycarbodiimide with a melting point of 70-90℃ and a decomposition temperature of ≥130℃.

4. The high-transparency, hydrolysis-resistant nylon composite material according to claim 3, characterized in that: The epoxy equivalent of the epoxy-functionalized cage-type silsesquioxane is 150-250 g / mol, preferably epoxy cyclohexyl-functionalized cage-type silsesquioxane; the dual hydrolysis-resistant protection mechanism of polymeric polycarbodiimide carboxyl end-capping and epoxy POSS dynamic crosslinking, together ensure that the tensile strength retention rate is ≥85% after cooking at 121℃ for 48 hours.

5. The high-transparency, hydrolysis-resistant nylon composite material according to claim 1, characterized in that: The composite antioxidant is a mixture of hindered phenolic antioxidant and phosphite auxiliary antioxidant in a mass ratio of 2:1; the hindered phenolic antioxidant is Irganox 1098, and the phosphite auxiliary antioxidant is Irgafos 168.

6. The high-transparency, hydrolysis-resistant nylon composite material according to claim 1, characterized in that: The lubricant is selected from one or more combinations of ethylene bis-stearamide and high molecular weight silicone powder.

7. A method for preparing a highly transparent, hydrolysis-resistant nylon composite material, characterized in that: Includes the following steps: S1. Raw material mixing: Add transparent nylon resin, carbodiimide hydrolytic stabilizer, epoxy functionalized cage-type silsesquioxane, composite antioxidant and lubricant to a high-speed mixer according to the weight ratio, mix for 3 to 8 minutes to obtain the mixture. S2, Twin-screw extrusion granulation: The mixture is added to a twin-screw extruder, the screw speed is 300 rpm, the entire process is vacuum de-exhausted, and the molten material is extruded through the die head and then cooled in a 30℃ water cooling tank; S3. Post-processing: The cooled extrudate is air-dried and pelletized to obtain granules; the granules are vacuum-dried at 80-100℃ for 3-4 hours to obtain recyclable, highly transparent, hydrolysis-resistant nylon composite material.

8. The method for preparing a highly transparent, hydrolysis-resistant nylon composite material according to claim 7, characterized in that: It also includes a recyclability verification step: the composite material granules obtained in step S3 are processed three times in the same way as steps S2-S3, and the mechanical properties and transparency retention rate of the material are tested after each recycling.

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