Functionalized impact polylactic acid and method for making same

Abstract

The application discloses a kind of functional impact poly-lactic acid, it is the blend of poly-lactic acid and functional polymer, with functional impact poly-lactic acid 100 parts as quality, functional polymer 3-20 parts, poly-lactic acid 80-97 parts;Functional polymer is selected from at least one of functional butadiene styrene rubber, SIBR integrated rubber, styrene-butadiene-styrene thermoplastic elastomer, styrene-isoprene-styrene thermoplastic elastomer, styrene-isoprene / butadiene-styrene thermoplastic elastomer, and the functional degree of functional polymer mole percentage is 1-10%.Compared with traditional toughening poly-lactic acid, the poly-lactic acid is modified by functional polymer in the application, and the amount of toughening material is less, the toughness is greatly improved, the strength and modulus loss is small, and the modified poly-lactic acid shows obvious toughness fracture, and the biodegradable performance is well maintained;Mixing and blending method equipment is simple, and production cost is low, and it has higher popularization and application value.

Description

Technical Field

[0001] This invention belongs to the field of polymer material modification technology, specifically relating to a method for preparing functionalized impact-resistant polylactic acid by toughening polylactic acid with functionalized polymers. Background Technology

[0002] Polylactic acid (PLA) is a commercially available thermoplastic material with renewable raw material sources. It exhibits good biocompatibility and biodegradability, gradually degrading in the human body and natural environment, ultimately breaking down into carbon dioxide and water. Therefore, PLA is one of the most promising biomaterials to replace traditional petroleum-based polymers, with wide applications in medicine, pharmaceuticals, agriculture, and packaging. While PLA possesses high strength and modulus, its relatively poor toughness limits its use in applications requiring a certain degree of flexibility.

[0003] To improve the toughness of general-purpose polylactic acid (PLA) and thus broaden its applications, research on PLA toughening modification has been booming in recent years. Incorporating flexible components such as rubber into PLA is an effective way to improve its toughness. However, most toughening rubbers have poor polarity and compatibility with PLA, resulting in less than ideal toughening effects. To improve the compatibility between rubber and PLA, the rubber's polarity can generally be increased by modification (such as epoxidation or grafting with polar groups like maleic anhydride), or by adding a third-component compatibilizer during blending. However, these methods involve numerous steps and are difficult to precisely control. Therefore, how to solve the complex effects of blending toughening processes and further improve the toughness of PLA is an urgent technical problem to be solved. Summary of the Invention

[0004] The purpose of this invention is to provide a type of functionalized impact-resistant polylactic acid and its preparation method to improve the toughness of impact-resistant polylactic acid resin. The main method is to toughen and modify polylactic acid by using functionalized polymers through intensive mixing and blending. The functionalized impact-resistant polylactic acid is a blend of polylactic acid and functionalized polymers.

[0005] The technical solution of the present invention is as follows: a type of functionalized impact-resistant polylactic acid, wherein the functionalized impact-resistant polylactic acid is a blend of polylactic acid and a functionalized polymer, wherein, based on 100 parts by mass of the functionalized impact-resistant polylactic acid, the functionalized polymer comprises 3-20 parts and the polylactic acid comprises 80-97 parts; the functionalization degree of the functionalized polymer is 1-10% in molar percentage.

[0006] The functionalized polymer is selected from at least one of functionalized styrene-butadiene rubber, functionalized SIBR integrated rubber, functionalized styrene-butadiene-styrene thermoplastic elastomer, functionalized styrene-isoprene-styrene thermoplastic elastomer, and functionalized styrene-isoprene / butadiene-styrene thermoplastic elastomer.

[0007] Preferably, the functionalized polymer is selected from at least one of the following: functionalized styrene-butadiene rubber copolymerized with 1,1-diphenylethylene derivatives and styrene and butadiene; functionalized SIBR integrated rubber copolymerized with 1,1-diphenylethylene derivatives and styrene, butadiene and isoprene; functionalized styrene-isoprene-styrene thermoplastic elastomer copolymerized with 1,1-diphenylethylene derivatives and styrene and butadiene; functionalized styrene-isoprene-styrene thermoplastic elastomer copolymerized with 1,1-diphenylethylene derivatives and styrene and isoprene; and functionalized styrene-isoprene / butadiene-styrene thermoplastic elastomer copolymerized with 1,1-diphenylethylene derivatives and styrene, butadiene and isoprene.

[0008] The 1,1-diphenylethylene derivative is selected from at least one of nitrogen-containing diphenylethylene, silicon-containing diphenylethylene, and nitrogen / silicon-containing diphenylethylene.

[0009] Preferably, the functionalized polymer is selected from at least one of nitrogen-containing / siloxane-based styrene-butadiene rubber, nitrogen-containing / siloxane-based SIBR integrated rubber, nitrogen-containing / siloxane-based styrene-butadiene-styrene copolymer (SBS), nitrogen-containing / siloxane-based styrene-isoprene-styrene copolymer (SIS), nitrogen-containing / siloxy-based styrene-butadiene rubber, nitrogen-containing / siloxy-based SIBR integrated rubber, nitrogen-containing / siloxy-based styrene-butadiene-styrene copolymer (SBS), and nitrogen-containing / siloxy-based styrene-isoprene-styrene copolymer (SIS).

[0010] Preferably, the functionalized polymer is selected from nitrogen-containing / silyl hydroxyl styrene-butadiene rubber.

[0011] Preferably, based on 100 parts by weight of functionalized impact-resistant polylactic acid, the functionalized polymer comprises 5-15 parts and the polylactic acid comprises 85-95 parts.

[0012] Preferably, the functionalized polymer has a linear or star-shaped structure.

[0013] Preferably, the polylactic acid is selected from L-polylactic acid.

[0014] Preferably, the polylactic acid has a number-average molecular weight of 50,000 to 300,000, and the functionalized polymer has a number-average molecular weight of 50,000 to 300,000.

[0015] Preferably, the polylactic acid has a number-average molecular weight of 100,000 to 200,000; the functionalized polymer has a number-average molecular weight of 100,000 to 200,000.

[0016] Preferably, the functionalization degree of the functionalized polymer is 5-8% molar percentage.

[0017] Preferably, the functionalized polymer is selected from nitrogen-containing / silyl styrene-butadiene rubber; based on 100 parts by weight of functionalized impact-resistant polylactic acid, the functionalized polymer comprises 8-10 parts and the polylactic acid comprises 90-92 parts.

[0018] Secondly, this invention discloses a method for preparing a type of functionalized impact-resistant polylactic acid, specifically: polylactic acid and functionalized polymer are mixed in an internal mixer for 10-20 minutes at a mixing temperature of 170-200℃ and a torque of 40-80 rpm to obtain functionalized impact-resistant polylactic acid.

[0019] Thirdly, this invention discloses the use of a class of functionalized polymers for toughening polylactic acid.

[0020] Beneficial effects

[0021] This invention has the following advantages: the impact resistance of functionalized impact-resistant polylactic acid is significantly improved. By modifying polylactic acid with functionalized polymers, the amount of modified material is small, the toughness is greatly improved, and the loss of strength and modulus is small. Functionalized impact-resistant polylactic acid exhibits obvious tough fracture, and the biodegradable characteristics of polylactic acid are well maintained. The internal mixing and blending toughening method is simple, efficient and easy to implement, and has low production cost, making it highly valuable for promotion and application. Detailed Implementation

[0022] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0023] Many specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the invention, and not all embodiments.

[0024] The preferred embodiments of the present invention will now be described in detail with reference to specific examples. It should be understood that the following examples are given for illustrative purposes only and are not intended to limit the scope of the present invention. Those skilled in the art can make various modifications and substitutions to the present invention without departing from its spirit and essence.

[0025] In this embodiment, the preparation method of the functionalized polymer in the chain is the classic anionic polymerization method, as detailed in the following references: Liu Pibo, Research on Living Anionic Polymerization of Amine / Alkoxysilyl DPE Derivatives, Doctoral Dissertation, Dalian University of Technology, 2019; Shen Heyu, Research on Anionic Polymerization of Primary Amine-Substituted Diphenylethylene Derivatives, Doctoral Dissertation, Dalian University of Technology, 2020; Design and Synthesis of Styrene / Diene Rubber and Research on the Properties of its Composites, Zhang Songbo, Doctoral Dissertation, Dalian University of Technology, 2021.

[0026] Mechanical performance testing:

[0027] Izod notched impact strength: Tested according to ASTM-D256 standard using an instrumented impact tester at a test temperature of 23°C and a pendulum weight of 5.5J.

[0028] Tensile properties: Tested according to ISO 527-1 standard using a universal testing machine, with a tensile rate of 10 mm / min and a test temperature of 23℃.

[0029] Each sample was repeated at least 5 times.

[0030] Example 1

[0031] Take 90 parts of L-polylactic acid and 10 parts of nitrogen-containing / silicone-based styrene-butadiene rubber (functionalization degree 7%, number average molecular weight 153,000). Mix the polylactic acid (number average molecular weight 145,000) and the functionalized rubber together in a mixer for 20 minutes at a mixing temperature of 175℃ and a torque of 70 rpm to obtain an impact-resistant polylactic acid material with an Izod impact strength of 435 J / m, a tensile strength of 57 MPa, a tensile modulus of 1.29 GPa, and an elongation at break of 205%.

[0032] Example 2 (The functionalization degrees of the functionalized polymers were 0%, 3%, 5%, 7%, 8%, 9%, 10%, and 15%, respectively; other aspects were the same as in Example 1)

[0033] 0％ 70 31 54 1％ 75 32 54 3％ 95 56 54 5％ 412 200 56 7％ 435 205 57 8％ 421 202 57 9％ 399 195 56 10％ 385 199 55 15％ 380 190 54

[0034] Example 3 (functionalized polymer ratios were 0%, 3%, 5%, 10%, 15%, 20%, and 25%, with other parameters the same as in Example 1)

[0035]

[0036]

[0037] Example 4 (The type of functionalized polymer was adjusted; otherwise, it was the same as Example 1)

[0038]

[0039] Example 5 (Adjusting the functionalization positions of the functionalized polymer, otherwise the same as Example 1)

[0040]

[0041] Comparative Example 1 (Polymer Unmodified)

[0042] Take 90 parts of L-polylactic acid (number average molecular weight of 116,000) and 10 parts of star-shaped polybutadiene rubber (number average molecular weight of 106,000). Mix the polylactic acid and rubber together in an internal mixer for 10 minutes at a mixing temperature of 170℃ and a torque of 60 rpm to obtain an impact-resistant polylactic acid material with an Izod impact strength of 74 J / m, a tensile strength of 50 MPa, a tensile modulus of 1.25 GPa, and an elongation at break of 28%.

[0043] Comparative Example 2 (Epoxidation)

[0044] Take 90 parts of L-polylactic acid (number average molecular weight of 116,000) and 10 parts of epoxidized star-shaped polybutadiene rubber (epoxidation degree of 21%, number average molecular weight of 107,000). Mix the polylactic acid and epoxidized rubber together in a mixer for 10 minutes at a mixing temperature of 170℃ and a torque of 60 rpm to obtain an impact-resistant polylactic acid material with an Izod impact strength of 384 J / m, a tensile strength of 54 MPa, a tensile modulus of 1.24 GPa, and an elongation at break of 158%.

[0045] Analysis revealed that to achieve optimal overall mechanical properties of polylactic acid (PLA) materials and a balance between strength and toughness, several key parameters of functionalized polymers work synergistically. These include: degree of functionalization, type of functionalized groups, amount of functionalized polymer added, type of functionalized polymer, and number-average molecular weight (number of functionalized polymers and PLA). Based on extensive experimentation, the inventors developed a superior technical solution for toughening PLA with functionalized polymers, resulting in approximately a 20% improvement in the overall mechanical properties of the prepared toughened PLA. The functionalized polymers improved polymer polarity and enhanced compatibility with PLA blends.

[0046] While the specific embodiments of the present invention have been described above, they are not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A type of functionalized impact-resistant polylactic acid, characterized in that, The functionalized impact-resistant polylactic acid is a blend of polylactic acid and a functionalized polymer. Based on 100 parts by mass of the functionalized impact-resistant polylactic acid, the functionalized polymer comprises 3-20 parts, and the polylactic acid comprises 80-97 parts; the functionalization degree of the functionalized polymer is 5-8% in molar percentage. The functionalized polymer is selected from at least one of the following: nitrogen-containing / siloxane-based styrene-butadiene rubber, nitrogen-containing / siloxane-based SIBR integrated rubber, nitrogen-containing / siloxane-based styrene-butadiene-styrene copolymer, nitrogen-containing / siloxane-based styrene-isoprene-styrene copolymer, nitrogen-containing / siloxy-based styrene-butadiene rubber, nitrogen-containing / siloxy-based SIBR integrated rubber, nitrogen-containing / siloxy-based styrene-butadiene-styrene copolymer, and nitrogen-containing / siloxy-based styrene-isoprene-styrene copolymer.

2. The functionalized impact-resistant polylactic acid according to claim 1, characterized in that, Based on 100 parts by weight of the functionalized impact-resistant polylactic acid, the functionalized polymer comprises 5-15 parts and the polylactic acid comprises 85-95 parts.

3. The functionalized impact-resistant polylactic acid according to claim 1, characterized in that, The functionalized polymer is selected from nitrogen-containing / silane-containing styrene-butadiene rubber; based on 100 parts by weight of functionalized impact-resistant polylactic acid, the functionalized polymer comprises 8-10 parts and the polylactic acid comprises 90-92 parts.

4. The functionalized impact-resistant polylactic acid according to any one of claims 1-3, characterized in that, The functionalized polymer has a linear or star-shaped structure.

5. The functionalized impact-resistant polylactic acid according to any one of claims 1-3, characterized in that, The polylactic acid has a number-average molecular weight of 50,000 to 300,000, and the functionalized polymer has a number-average molecular weight of 50,000 to 300,000.

6. The functionalized impact-resistant polylactic acid according to claim 5, characterized in that, The polylactic acid has a number-average molecular weight of 100,000 to 200,000; the functionalized polymer has a number-average molecular weight of 100,000 to 200,000.

7. A method for preparing functionalized impact-resistant polylactic acid as described in any one of claims 1-3 and 6, characterized in that, Functionalized impact-resistant polylactic acid can be obtained by mixing polylactic acid and functionalized polymer in an internal mixer for 10-20 minutes at a mixing temperature of 170-200℃ and a torque of 40-80 rpm.

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