Efficient toughened biodegradable engineering plastic and preparation method thereof

Abstract

The invention discloses efficient toughened biodegradable engineering plastic and a preparation method thereof. The biodegradable engineering plastic is prepared from modified biodegradable polyester resin, an organic micromolecule toughening synergist, a compatible auxiliary agent, an antioxidant and a processing stabilizing auxiliary agent. A low-molecular modifier containing hydroxyl and acylamino is introduced into a polylactic acid molecular chain, a dynamic hydrogen bond type branched structure is constructed, and the problems that polylactic acid is high in brittleness and insufficient in impact toughness are effectively solved; meanwhile, an organic micromolecule toughening synergist with an aromatic ring and active hydroxyl structure is introduced and forms stable hydrogen-bond interaction with the modified polyester resin, so that the impact resistance and the elongation at break of the material are further improved. According to the biodegradable engineering plastic prepared by the invention, the mechanical property and the thermal stability are remarkably improved while good biodegradability is maintained, and the biodegradable engineering plastic is suitable for the application field of engineering plastics with relatively high requirements on toughness and durability.

Description

Technical Field

[0001] This invention relates to the field of polymer materials, specifically to a highly efficient toughened biodegradable engineering plastic and its preparation method. Background Technology

[0002] With increasing global focus on environmental protection and sustainable development, biodegradable plastics, as a green material to replace traditional petroleum-based plastics, have gradually gained widespread application. Biodegradable polyesters such as polylactic acid (PLA) and polybutylene succinate (PBS) have become a research focus due to their excellent environmental friendliness. PLA, in particular, as a typical biodegradable material, possesses good biodegradability and can be degraded by microorganisms in the natural environment, thereby reducing environmental pollution. However, despite PLA's excellent biodegradability, its use in engineering applications is limited by its inherent brittleness and low toughness, especially in fields requiring high impact strength and mechanical strength, such as automobiles, electronic devices, and building materials.

[0003] Traditionally, researchers have employed methods such as rubber blending, filler reinforcement, and graft copolymerization to improve the toughness of polylactic acid (PLA) and other biodegradable plastics. While these methods have improved the toughness of the materials to some extent, they generally suffer from the problem of non-degradable toughening agents affecting the environmental properties of the plastics. Furthermore, some toughening agents may migrate or precipitate during use, leading to insufficient long-term stability and durability of the materials. Nevertheless, these methods have limited effectiveness in improving the impact strength, elongation at break, and processing stability of the materials. Therefore, it is difficult to maintain biodegradability and environmental friendliness while simultaneously improving the mechanical properties of materials using current technologies.

[0004] To overcome these technical bottlenecks, recent studies have proposed innovative modification methods to improve the performance of biodegradable plastics. For example, introducing dynamic hydrogen-bonded branched structures into the polylactic acid (PLA) molecular chain enhances intermolecular interactions, improving the material's toughness and mechanical properties. Simultaneously, introducing certain small-molecule organic compounds with toughening effects can improve the plastic's impact toughness without affecting its biodegradability. However, currently, a comprehensive technical solution for toughening and modifying biodegradable plastics that can significantly improve toughness and mechanical properties while maintaining excellent degradation performance is still lacking.

[0005] Therefore, developing a technology to improve the toughness and durability of biodegradable engineering plastics through innovative modification methods, which can meet the growing demand for high performance while ensuring environmental friendliness and promoting the widespread application of biodegradable plastics, has become an important technical problem that urgently needs to be solved. Summary of the Invention

[0006] To overcome the technical challenges mentioned above, the present invention aims to provide a highly efficient toughened biodegradable engineering plastic and its preparation method. This invention improves the toughness and mechanical properties of the material through innovative modification methods while maintaining its excellent biodegradability. The present invention uses a modified biodegradable polyester resin. By introducing a dynamic hydrogen-bonded branched structure into polylactic acid, the intermolecular interaction forces are enhanced. An organic small-molecule toughening synergist is introduced to form hydrogen bonds with the modified polyester, further improving the material's impact toughness and crack resistance. Through the composite of modified biodegradable polyester resin and organic small-molecule toughening synergist, the present invention significantly improves the material's impact toughness, elongation at break, and long-term stability, while maintaining its biodegradability, thus adapting to high-performance and environmentally friendly engineering plastic applications.

[0007] The objective of this invention can be achieved through the following technical solutions: A highly efficient toughened biodegradable engineering plastic comprises the following raw materials in parts by weight: 60-85 parts of modified biodegradable polyester resin; 3-15 parts of organic small molecule toughening synergist; 1-5 parts of compatibility agent; 0.2-1.0 parts of antioxidant; and 0.2-1.0 parts of processing stabilizing agent. The modified biodegradable polyester resin, through the introduction of a low-molecular-weight modifier containing hydroxyl and amide groups, 2,2'-diaminodiphenylmethane, into the polylactic acid molecular chain, forms a dynamic hydrogen-bonded branched structure, enhancing the material's impact toughness and mechanical properties while maintaining its excellent biodegradability, making it suitable for high-strength, durable engineering plastic applications. The organic small molecule toughening synergist is 2,6-dihydroxyacetophenone, possessing an aromatic ring and active hydroxyl structure, which can form hydrogen bonds with the amide and ester groups in the modified biodegradable polyester resin, improving interfacial compatibility, enhancing the material's impact resistance and elongation at break, thereby achieving a toughening effect, especially exhibiting excellent toughness and durable mechanical properties under high stress environments.

[0008] Optionally, the modified biodegradable polyester resin comprises the following raw materials in parts by weight: 80-100 parts of polylactic acid; 5-15 parts of 2,2'-diaminodiphenylmethane; 0.5-1.5 parts of hindered phenolic antioxidant; 0.5-3 parts of talc; 2-8 parts of trioctyl ester; 0.5-2.0 parts of benzoyl peroxide; and 0.1-0.5 parts of 2-phenylbenzimidazole.

[0009] Optionally, the preparation method of the modified biodegradable polyester resin includes the following steps: (1) Add polylactic acid and 2,2'-diaminodiphenylmethane to the reaction vessel in proportion, and adjust the temperature until modified polylactic acid with branched structure is obtained.

[0010] (2) Modified polylactic acid, hindered phenolic antioxidant, talc, trioctyl ester, benzoyl peroxide, and 2-phenylbenzimidazole are added to a mixer in a predetermined ratio and mixed evenly until all components are evenly dispersed to obtain modified biodegradable polyester resin.

[0011] Optionally, the reaction conditions in step (1) are to adjust the temperature to 160-180°C and carry out the melting reaction for 2-3 hours under nitrogen protection.

[0012] Optionally, the reaction conditions in step (2) are a temperature controlled at 170–200°C and a mixing time of 10–15 minutes.

[0013] Optionally, the compatibility aid is a mixture of bio-based ester compatibility agent and silica at a mass ratio of 2:1; the antioxidant is a mixture of hindered phenolic antioxidant and phosphite antioxidant at a mass ratio of 1:0.5; and the processing stabilizing aid is a mixture of fatty acid salt lubricant and graphene at a mass ratio of 3:1.

[0014] Optionally, a method for preparing a highly efficient toughened biodegradable engineering plastic includes the following steps: adding modified biodegradable polyester resin, hindered phenolic antioxidant, talc, trioctyl ester, benzoyl peroxide, and 2-phenylbenzimidazole into a mixer in a predetermined ratio, and mixing them uniformly until all components are uniformly dispersed to obtain a highly efficient toughened biodegradable engineering plastic.

[0015] Optionally, the mixing conditions are a temperature controlled at 170–200°C and a mixing time of 10–15 minutes.

[0016] The beneficial effects of this invention are: This invention introduces a dynamic hydrogen-bonded branched structure into polylactic acid (PLA), enhancing the intramolecular interaction forces and significantly improving its impact toughness and elongation at break, thus solving the problem of excessive brittleness and easy fracture in traditional PLA. Simultaneously, the use of 2,6-dihydroxyacetophenone, a small-molecule toughening synergist, further improves the material's crack resistance through hydrogen bonding, enhancing its impact resistance under high stress environments. Furthermore, this invention maintains the biodegradability of PLA while enhancing its mechanical properties, preserving its environmental characteristics and making it more promising for high-strength, long-life applications. Attached Figure Description

[0017] The invention will now be further described with reference to the accompanying drawings.

[0018] Figure 1 A method for preparing highly efficient toughened biodegradable engineering plastics; Figure 2 A comparison chart of impact toughness and tensile properties test results for samples with different formulation ratios; Figure 3 A comparison chart showing the Vicat softening point test and biodegradability test results for samples with different formulation ratios. Detailed Implementation

[0019] The present invention will be further described below with reference to specific embodiments. However, the present invention is not limited to the following embodiments. Equivalent adjustments made without departing from the spirit and essence of the present invention should also be considered to fall within the protection scope of the present invention.

[0020] Example 1: Objective: This embodiment aims to verify how the use of modified biodegradable polyester resin can improve the impact toughness and crack resistance of the material, and to evaluate its performance under high load conditions.

[0021] step: S1, Preparation of modified biodegradable polyester resin 100 parts of polylactic acid and 15 parts of 2,2'-diaminodiphenylmethane were added to a reaction vessel in a certain proportion. 1.5 parts of hindered phenolic antioxidant and 3 parts of talc were added. The temperature was adjusted to 170°C, and the mixture was melt-reacted for 2.5 hours under nitrogen protection until the modified biodegradable polyester resin was obtained. During this process, 2,2'-diaminodiphenylmethane reacted with polylactic acid to form a dynamic hydrogen-bonded branched structure, which enhanced the intermolecular interaction forces of the material and improved its impact toughness. S2, Mixing and molding of toughening synergists The modified biodegradable polyester resin obtained in step S1 is added to a mixer in a predetermined ratio along with 8 parts of trioctyl ester, 2 parts of benzoyl peroxide, and 0.5 parts of 2-phenylbenzimidazole. The temperature is controlled at 180°C and the mixing time is 15 minutes until all components are uniformly dispersed, thus obtaining a highly efficient and toughened biodegradable engineering plastic.

[0022] Example 2: Objective: This embodiment aims to verify the effect of a reasonable ratio of modified biodegradable polyester resin to toughening synergist on the toughness and mechanical properties of the material.

[0023] step: S1, Preparation of modified biodegradable polyester resin 90 parts of polylactic acid and 10 parts of 2,2'-diaminodiphenylmethane were added to a reaction vessel in a certain proportion. 1.0 part of hindered phenolic antioxidant and 2 parts of talc were added. The temperature was adjusted to 165℃, and the reaction was carried out under nitrogen protection for 2 hours until the modified biodegradable polyester resin was obtained. The reaction between 2,2'-diaminodiphenylmethane and polylactic acid generates a branched structure, which improves the impact toughness of the material. S2, Mixing and molding of toughening synergists The modified biodegradable polyester resin obtained in step S1 is added to a mixer in a predetermined ratio along with 5 parts of trioctyl ester, 1.5 parts of benzoyl peroxide, and 0.3 parts of 2-phenylbenzimidazole. The temperature is controlled at 175°C and the mixing time is 12 minutes until all components are uniformly dispersed, thus obtaining a highly efficient and toughened biodegradable engineering plastic.

[0024] Example 3: Objective: This embodiment aims to test the toughening effect and application performance of modified biodegradable polyester resin under low formulation conditions.

[0025] step: S1, Preparation of modified biodegradable polyester resin 80 parts of polylactic acid and 5 parts of 2,2'-diaminodiphenylmethane were added to a reaction vessel in a certain proportion. 0.5 parts of hindered phenolic antioxidant and 1 part of talc were added. The temperature was adjusted to 160℃, and the reaction was carried out under nitrogen protection for 2 hours until the modified biodegradable polyester resin was obtained. The reaction between 2,2'-diaminodiphenylmethane and polylactic acid formed a branched structure, which enhanced the intermolecular hydrogen bonds and improved the toughness. S2, Mixing and molding of toughening synergists The modified biodegradable polyester resin obtained in step S1 is added to a mixer in a predetermined ratio along with 2 parts of trioctyl ester, 1 part of benzoyl peroxide, and 0.2 parts of 2-phenylbenzimidazole. The temperature is controlled at 170°C and the mixing time is 10 minutes until all components are uniformly dispersed, thus obtaining a highly efficient and toughened biodegradable engineering plastic.

[0026] Comparative Example 1: Objective: This comparative example aims to verify the performance comparison of unmodified biodegradable polyester resin under the action of toughening synergists and to evaluate the toughening effect of modified biodegradable polyester resin.

[0027] step: S1, Preparation of unmodified biodegradable polyester resin 90 parts of polylactic acid were directly added to a reactor, along with 1.0 part of hindered phenolic antioxidant and 2 parts of talc. The temperature was adjusted to 165°C, and the mixture was melt-reacted for 2 hours under nitrogen protection. This step did not involve any modification reaction, and the resulting product was still an unmodified biodegradable polyester resin with low mechanical properties.

[0028] S2, Mixing and molding of toughening synergists The unmodified biodegradable polyester resin obtained in step S1 is added to a mixer in a predetermined ratio along with 5 parts of trioctyl ester, 1.5 parts of benzoyl peroxide, and 0.3 parts of 2-phenylbenzimidazole. The temperature is controlled at 175°C and the mixing time is 12 minutes until all components are uniformly dispersed, thus obtaining toughened biodegradable engineering plastic.

[0029] Comparative Example 2: Objective: This comparative example aims to verify the performance changes of modified polylactic acid without the use of organic small molecule toughening synergists, so as to highlight the role of organic small molecule toughening synergists in improving material performance.

[0030] step: S1, Preparation of modified biodegradable polyester resin 90 parts of polylactic acid and 10 parts of 2,2'-diaminodiphenylmethane were added to a reaction vessel in a certain proportion. 1.0 part of hindered phenolic antioxidant and 2 parts of talc were added. The temperature was adjusted to 165℃ and the melt reaction was carried out for 2 hours under nitrogen protection until the modified biodegradable polyester resin was obtained, forming a dynamic hydrogen bond branched structure, which improved the impact toughness of the material. S2, Mixing and molding of toughening synergists The modified biodegradable polyester resin obtained in step S1 was added to a mixer in a predetermined ratio along with 5 parts of trioctyl ester, 1.5 parts of benzoyl peroxide, and 0.3 parts of 2-phenylbenzimidazole. The temperature was controlled at 175°C, and the mixing time was 12 minutes, until all components were uniformly dispersed, resulting in a toughened biodegradable engineering plastic. Small molecule toughening agents such as 2,6-dihydroxyacetophenone were not used in this step to verify their effect on impact toughness and elongation at break.

[0031] Performance testing: 1. Impact toughness test This test aims to evaluate the toughness performance of biodegradable engineering plastics with different formulations under impact, especially their impact resistance and energy absorption. Biodegradable engineering plastics prepared with different formulations were processed into standard-sized specimens. Impact tests were conducted using a Charpy impact testing machine, and the fracture characteristics of the materials after being subjected to impacts of specific energy were recorded. During the test, the specimens were stored under specified temperature and humidity conditions for 24 hours to ensure the consistency of the experimental environment. The impact strength obtained from the test is expressed in kJ / m². 2 To evaluate the impact toughness of a material, a higher value indicates better toughness.

[0032] 2. Tensile property test This test aims to evaluate the tensile strength, elongation at break, and other properties of materials, and to understand the elasticity and tensile strength of materials with different formulations. Tensile properties of biodegradable engineering plastics with different formulations were tested using an electronic universal testing machine according to GB / T1040 standard. The specimens were standard tensile bars, the tensile speed was set to 50 mm / min, the temperature was controlled at 23℃, and the humidity was controlled at 50%. During the test, the tensile strength (MPa) and elongation at break (%) were recorded to evaluate the material's performance under tensile load.

[0033] 3. Vicat softening point test This test is used to evaluate the thermal stability and softening properties of materials under heated conditions, especially the material's ability to retain its shape at higher temperatures.

[0034] The thermal stability of biodegradable engineering plastics with different formulations was tested using a Vicat softening point tester. The sample was heated to a certain temperature and the temperature was increased at a rate of 5°C / min. The temperature at which the material began to deform under heat was defined as the Vicat softening point. The test temperature was initially increased from 50°C until the sample began to show significant deformation. By comparing the softening point temperatures of each formulation, the thermal stability and performance in high-temperature environments of the materials were evaluated.

[0035] 4. Biodegradability test This test aims to evaluate the degradation rate and degradation effect of biodegradable engineering plastics with different formulations in natural or simulated environmental conditions. Samples of biodegradable engineering plastics with different formulations were placed in soil / compost environments to simulate the degradation process under natural conditions. According to ISO 17556, samples were periodically sampled and weighed, and the mass change of the samples over 60 days was recorded to calculate their biodegradation rate.

[0036] Table 1 Performance Test Results

[0037] According to the performance test results in Table 1, Example 2 performed excellently in all test items, especially in impact toughness, with a value of 18.5 KJ / m. 2 This is significantly higher than that of Comparative Example 1 and Comparative Example 2, whose impact toughness is 12.4 KJ / m. 2 and 13.1 KJ / m 2 This verified the effective toughening effect of the modified biodegradable polyester resin and the toughening synergist. Furthermore, Example 2 exhibited the highest tensile strength of 33.7 MPa among all examples, compared to Comparative Example 1 and Comparative Example 2, which showed lower tensile strengths of 25.2 MPa and 26.5 MPa, respectively, indicating that Example 2 possessed better tensile strength under stress.

[0038] In the elongation at break test, Example 2 showed the best performance with an elongation at break of 50.3%. In contrast, Comparative Example 1 and Comparative Example 2 had lower elongations at break of 35.8% and 37.4%, respectively, further verifying the advantage of Example 2 in improving material ductility. Example 2 had a Vicat softening point of 96.5℃, demonstrating good thermal stability and adaptability to high-temperature environments. The Vicat softening points of Comparative Example 1 and Comparative Example 2 were 85.7℃ and 87.2℃, respectively, significantly lower than those of Example 2.

[0039] Example 2 showed the best biodegradability rate of 89.7%, indicating that its degradation performance in the natural environment was significantly better than that of Comparative Example 1 and Comparative Example 2, which had degradation rates of 78.3% and 80.1%, respectively.

[0040] Example 2 showed the best performance in terms of impact toughness, tensile strength, elongation at break, thermal stability and biodegradability. In particular, it was significantly better than Comparative Example 1 and Comparative Example 2 in terms of toughening effect and biodegradability, which verified the superior effect of the modified biodegradable polyester resin and toughening synergist of the present invention.

Claims

1. A highly efficient toughened biodegradable engineering plastic, characterized in that, The biodegradable engineering plastic comprises the following raw materials in parts by weight: 60-85 parts of modified biodegradable polyester resin; 3-15 parts of organic small molecule toughening synergist; 1-5 parts of compatibility agent; 0.2-1.0 parts of antioxidant; and 0.2-1.0 parts of processing stabilizing agent. The modified biodegradable polyester resin, by introducing a low-molecular-weight modifier containing hydroxyl and amide groups, 2,2'-diaminodiphenylmethane, into the polylactic acid molecular chain, forms a dynamic hydrogen-bonded branched structure, enhancing the material's impact toughness and mechanical properties while maintaining its excellent biodegradability, making it suitable for high-strength, durable engineering plastic applications. The organic small molecule toughening synergist is 2,6-dihydroxyacetophenone, possessing an aromatic ring and active hydroxyl structure, which can form hydrogen bonds with the amide and ester groups in the modified biodegradable polyester resin, improving interfacial compatibility, enhancing the material's impact resistance and elongation at break, thereby achieving a toughening effect, especially exhibiting excellent toughness and durable mechanical properties under high stress environments.

2. The highly efficient toughened biodegradable engineering plastic according to claim 1, characterized in that, The modified biodegradable polyester resin comprises the following raw materials in parts by weight: 80-100 parts of polylactic acid; 5-15 parts of 2,2'-diaminodiphenylmethane; 0.5-1.5 parts of hindered phenolic antioxidant; 0.5-3 parts of talc; 2-8 parts of trioctyl ester; 0.5-2.0 parts of benzoyl peroxide; and 0.1-0.5 parts of 2-phenylbenzimidazole.

3. A highly efficient toughened biodegradable engineering plastic according to claim 1 or 2, characterized in that, The preparation method of the modified biodegradable polyester resin includes the following steps: (1) Add polylactic acid and 2,2'-diaminodiphenylmethane to a reaction vessel in proportion, and adjust the temperature until modified polylactic acid with a branched structure is obtained; (2) Modified polylactic acid, hindered phenolic antioxidant, talc, trioctyl ester, benzoyl peroxide, and 2-phenylbenzimidazole are added to a mixer in a predetermined ratio and mixed evenly until all components are evenly dispersed to obtain modified biodegradable polyester resin.

4. The high-efficiency toughened biodegradable engineering plastic according to claim 1, characterized in that, The reaction conditions for step (1) are to adjust the temperature to 160-180°C and carry out the melting reaction for 2-3 hours under nitrogen protection.

5. The highly efficient toughened biodegradable engineering plastic according to claim 1, characterized in that, The reaction conditions for step (2) are a temperature of 170-200°C and a mixing time of 10-15 minutes.

6. The highly efficient toughened biodegradable engineering plastic according to claim 1, characterized in that, The compatibility aid is composed of a bio-based ester compatibility agent and silica in a mass ratio of 2:1; the antioxidant is composed of a hindered phenolic antioxidant and a phosphite antioxidant in a mass ratio of 1:0.5; and the processing stabilizing aid is composed of a fatty acid salt lubricant and graphene in a mass ratio of 3:

1.

7. A method for preparing a highly efficient toughened biodegradable engineering plastic, wherein the highly efficient toughened biodegradable engineering plastic is as described in any one of claims 1 to 6, characterized in that, Includes the following steps: Modified biodegradable polyester resin, hindered phenolic antioxidant, talc, trioctyl ester, benzoyl peroxide, and 2-phenylbenzimidazole are added to a mixer in a predetermined ratio and mixed evenly until all components are uniformly dispersed to obtain a highly efficient and toughened biodegradable engineering plastic.

8. The method for preparing a highly efficient toughened biodegradable engineering plastic according to claim 7, characterized in that, The mixing conditions are a temperature controlled at 170–200°C and a mixing time of 10–15 minutes.

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