Polylactic acid composite material and preparation method thereof

Abstract

The invention provides a polylactic acid composite material and a preparation method thereof. The polylactic acid composite material comprises the following components in parts by mass: 50-90 parts of polylactic acid, 5-50 parts of bio-based polycarbonate, 5-15 parts of an impact modifier and 0.1-3 parts of a chain extender, wherein the bio-based polycarbonate has the following structural unit: in the bio-based polycarbonate, R1 is selected from cyclohexenyl and-(CH2) n-, and n is equal to 0-6. The material provided by the invention also has good toughness and heat resistance on the basis of environmental friendliness.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a polylactic acid composite material and its preparation method. Background Technology

[0002] In recent years, bio-based polymer materials have developed rapidly, with a large number of bio-based plastics such as polylactic acid being developed. This has brought new hope for solving the environmental pollution problems caused by petroleum-based plastics. Under specific conditions (such as composting or high-temperature biogas fermentation), bio-based plastics can be degraded into water and carbon dioxide by natural microorganisms, returning to the green cycle of nature.

[0003] Polylactic acid (PLA) has become one of the most promising environmentally friendly bio-based polymer materials due to its excellent performance and cost-effectiveness. Research on high-performance PLA-based blends and composites for high-value-added applications is particularly noteworthy. However, PLA itself has poor toughness, lacks flexibility and elasticity, and has poor thermal stability, which limits its widespread application in various industries. The main shortcomings of PLA are: (1) Mechanical properties: PLA is brittle at room temperature and has poor impact resistance; (2) Thermal stability: It is sensitive to heat and is easily degraded at high temperatures, resulting in a decrease in material performance. The poor thermal stability of PLA materials limits its application in heat-resistant applications, especially in the field of disposable heat-resistant straws.

[0004] Researchers are exploring methods to modify the heat resistance of polylactic acid (PLA). For example, CN112646334A provides a high-strength, heat-resistant modified PLA, whose raw materials include a heat-resistant toughening agent obtained by copolymerization of modified lithium saponite, acrylate, and methacrylate. This composite material simultaneously meets the requirements of excellent toughness and heat resistance. CN106893276A provides a high-flexibility and heat-resistant modified PLA material and its preparation method, which simultaneously improves the heat resistance and toughness of PLA by combining poly(L) PLA homopolymer, poly(D) PLA copolymer, toughening and heat-resistant modifier, plasticizer, heat stabilizer, lubricant, and nucleating agent.

[0005] However, existing technologies lack modified polylactic acid-based composite materials that can simultaneously achieve environmental friendliness. Summary of the Invention

[0006] To address the aforementioned problems in the prior art, this invention provides a polylactic acid (PLA) composite material and its preparation method. PLA is a bio-based biodegradable material. The composite material of this invention utilizes bio-based polycarbonate (PC) for compounding, resulting in a material that is not only environmentally friendly but also possesses good toughness and heat resistance.

[0007] To achieve the above objectives, according to a first aspect of the present invention, a polylactic acid composite material is provided, comprising, by weight parts:

[0008] Polylactic acid 50-90 parts, bio-based polycarbonate 5-50 parts, impact modifier 5-15 parts, chain extender 0.1-3 parts

[0009] The bio-based polycarbonate has the following structural units:

[0010] R1 is selected from cyclohexenyl and -(CH2). n -, n = 0 to 6.

[0011] The polylactic acid composite material of the present invention is not only environmentally friendly, but also has good toughness and heat resistance.

[0012] In some preferred embodiments of the present invention, the polylactic acid composite material comprises, by weight, 60-90 parts of polylactic acid, 10-50 parts of bio-based polycarbonate, 5-10 parts of impact modifier, and 0.1-2.5 parts of chain extender. The polylactic acid composite material having the above preferred proportions exhibits superior toughness and heat resistance.

[0013] In some preferred embodiments of the present invention, the bio-based component accounts for 40% to 90% by mass in the bio-based polycarbonate.

[0014] In some preferred embodiments of the present invention, the bio-based component contains a bisphenol A structural unit derived from one or more combinations of isosorbide, vegetable oil, and residual oil derivatives.

[0015] In some preferred embodiments of the present invention, the polylactic acid has a weight-average molecular weight of 80,000 to 300,000 g / mol.

[0016] In some preferred embodiments of the present invention, the bio-based polycarbonate has a weight-average molecular weight of 50,000-150,000 g / mol.

[0017] In some preferred embodiments of the present invention, the impact modifier comprises a polymer containing polymethyl methacrylate (PMMA) segments. This preferred impact modifier can improve the compatibility of PLA and bio-based PC composites, and therefore, when this preferred impact modifier is added to the polylactic acid composite of the present invention, it can better enhance the toughness of the composite.

[0018] In some preferred embodiments of the present invention, the impact modifier comprises a polymer having a core-shell structure, wherein the shell material comprises a polymer containing polymethyl methacrylate segments.

[0019] In some preferred embodiments of the present invention, the impact modifier includes methyl methacrylate-butadiene-styrene copolymer toughening agents (MBS) and core-shell toughening agents (such as PARALOID). TM One or a combination of two or more of the following: BPM-520, acrylate-methyl methacrylate copolymer core-shell impact modifier (Kane Ace M-577), and methyl methacrylate-butyl acrylate-methyl methacrylate triblock copolymer toughening agent (Arkema Nanostrength).

[0020] In some preferred embodiments of the present invention, the chain extender is ethylene-maleic anhydride copolymer and / or ethylene-acrylate-maleic anhydride copolymer.

[0021] In some preferred embodiments of the present invention, the maleic anhydride structural unit accounts for 15-78% of the mass of the chain extender.

[0022] In some preferred embodiments of the present invention, the polylactic acid composite material further includes an antioxidant;

[0023] Preferably, the antioxidant is present in 0.05 to 0.5 parts by weight;

[0024] Preferably, the antioxidant includes one or a combination of two or more of polyphenolic antioxidants, phosphite antioxidants, and vitamin E; more preferably, a combination of two or more of polyphenolic antioxidants, phosphite antioxidants, and vitamin E is selected.

[0025] The present invention also provides a method for preparing the above-mentioned polylactic acid composite material, comprising:

[0026] Polylactic acid, bio-based polycarbonate, impact modifier, chain extender, and optional antioxidant are mixed in parts by mass, and then processed and molded to obtain the polylactic acid composite material.

[0027] In some preferred embodiments of the present invention, antioxidants are also added during the preparation process.

[0028] In some preferred embodiments of the present invention, the processing and molding method includes: extrusion granulation using a screw extruder;

[0029] Preferably, the temperature of the feeding section is 70–120°C, the temperature of the mixing section is 165–200°C, and the temperature of the plasticizing section is 175–220°C.

[0030] Preferably, the head temperature is 175–190°C;

[0031] Preferably, the screw speed is 50 to 120 revolutions per minute.

[0032] In some preferred embodiments of the present invention, the polylactic acid, the bio-based polycarbonate, and the impact modifier are dried separately and then mixed.

[0033] Compared to existing technologies, this invention provides a polylactic acid-based composite material that is environmentally friendly and also possesses good toughness and heat resistance. Compared to pure polylactic acid, the composite material of this invention exhibits a significantly increased Vicat softening temperature and a significantly improved notched impact strength.

[0034] Meanwhile, by adding impact modifiers and chain extenders, the compatibility of the PLA / PC two-phase interface can be effectively improved, and the size of the impact-resistant dispersed phase can be refined, increasing the toughening effect of the dispersed phase on PLA, thereby greatly improving the toughness of polylactic acid composite materials.

[0035] In summary, this invention provides a high-toughness and high-heat-resistant polylactic acid composite material, which effectively improves the disadvantages of PLA's poor heat resistance and brittleness, and further broadens the application range of PLA. Attached Figure Description

[0036] Figure 1 Scanning electron microscope (SEM) images of the polymers obtained in Comparative Example 2, Comparative Example 3, Example 2, and Example 4 are shown. Detailed Implementation

[0037] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0038] In the following examples and comparative examples, unless otherwise specified, all parts refer to parts by mass, and all molecular weights refer to weight-average molecular weights.

[0039] Example 1

[0040] This embodiment provides a polylactic acid composite material, the raw material composition of which, by mass parts, includes:

[0041] Polylactic acid (molecular weight 80000 g / mol): 70 parts;

[0042] Bio-based polycarbonate (DURABIO D7340R): 30 parts; of which, the bio-based component accounts for 85% by mass.

[0043] Impact modifier BPM520: 10 parts;

[0044] Chain extender Zemac E60P: 0.2 parts;

[0045] Antioxidant Irganox 1010: 0.05 parts.

[0046] The specific preparation method of this polylactic acid composite material includes the following steps:

[0047] Polylactic acid and bio-based polycarbonate were dried in a vacuum oven at 80°C for 8 hours, while impact modifier and chain extender were dried in a vacuum oven at 40°C for 8 hours.

[0048] Dried polylactic acid, bio-based polycarbonate, impact modifier, chain extender, and antioxidant were melt-blended in a twin-screw extruder at a screw speed of 100 rpm for 5 minutes to obtain a polylactic acid composite material.

[0049] The temperature control in the twin-screw extruder is as follows: 110℃ in the feeding section, 175℃ in the mixing section, 200℃ in the plasticizing section, and 180℃ in the die head.

[0050] Example 2

[0051] This embodiment provides a polylactic acid composite material, the raw material composition of which, by mass parts, includes:

[0052] Polylactic acid (molecular weight 100,000 g / mol): 60 parts;

[0053] Bio-based isosorbide-based polycarbonate: 40 parts; of which, the bio-based component accounts for 80% by mass.

[0054] The bio-based polycarbonate is isosorbide polycarbonate with a molecular weight of 100,000 g / mol, and its molecular chain has the following structural units:

[0055]

[0056] Where R1 is cyclohexenyl;

[0057] Impact modifier Kane Ace M-577: 10 parts;

[0058] Chain extender Zemac E60p: 0.2 parts;

[0059] Antioxidant (Irganox 1010): 0.03 parts;

[0060] Antioxidant (Irganox 168): 0.02 parts.

[0061] The specific preparation method of this polylactic acid composite material includes the following steps:

[0062] Polylactic acid and bio-based polycarbonate were dried in a vacuum oven at 80°C for 8 hours, while impact modifier and chain extender were dried in a vacuum oven at 40°C for 8 hours.

[0063] Dried polylactic acid, bio-based polycarbonate, impact modifier, chain extender, and antioxidant were melt-blended in a twin-screw extruder at a screw speed of 100 rpm for 5 min to obtain a polylactic acid composite material.

[0064] The temperature control in the twin-screw extruder is as follows: 110℃ in the feeding section, 175℃ in the mixing section, 200℃ in the plasticizing section, and 180℃ in the die head.

[0065] Example 3

[0066] This embodiment provides a polylactic acid composite material, the raw material composition of which, by mass parts, includes:

[0067] Polylactic acid (molecular weight 300,000 g / mol): 50 parts;

[0068] Bio-based polycarbonate (poly(isosorbide succinate)): 50 parts; wherein the bio-based component accounts for 75% by mass; the bio-based polycarbonate is isosorbide polycarbonate with a molecular weight of 80,000 g / mol and has the following structural units:

[0069]

[0070] Wherein, R1 is (CH2)2;

[0071] Impact modifier BPM520: 5 parts;

[0072] Chain extender M600: 0.2 parts;

[0073] Antioxidant (Irganox 1076): 0.5 parts.

[0074] The specific preparation method of this polylactic acid composite material includes the following steps:

[0075] Polylactic acid and bio-based polycarbonate were dried in a vacuum oven at 80°C for 8 hours, while impact modifier and chain extender were dried in a vacuum oven at 40°C for 8 hours.

[0076] Dried polylactic acid, bio-based polycarbonate, impact modifier, chain extender, and antioxidant were melt-blended in a twin-screw extruder at a screw speed of 100 rpm for 5 minutes to obtain a polylactic acid composite material.

[0077] The temperature control in the twin-screw extruder is as follows: 110℃ in the feeding section, 175℃ in the mixing section, 220℃ in the plasticizing section, and 180℃ in the die head.

[0078] Example 4:

[0079] This embodiment provides a polylactic acid composite material, the raw material composition of which, by mass parts, includes:

[0080] Polylactic acid (molecular weight 150,000 g / mol): 50 parts;

[0081] Bio-based polycarbonate (DURABIO D6350R): 50 parts; of which, the bio-based component accounts for 75% by mass.

[0082] Impact modifier Kane Ace M-577: 10 parts;

[0083] Chain extender Zemac E60p: 0.2 parts;

[0084] Antioxidant (Irganox B225): 0.2 parts.

[0085] The specific preparation method of this polylactic acid composite material includes the following steps:

[0086] Bio-based polylactic acid and bio-based polycarbonate were dried in a vacuum oven at 80°C for 8 hours, and impact modifier and chain extender were dried in a vacuum oven at 40°C for 8 hours.

[0087] Dried polylactic acid, bio-based polycarbonate, impact modifier, chain extender, and antioxidant were melt-blended in a twin-screw extruder at a screw speed of 100 rpm for 5 minutes to obtain a polylactic acid composite material.

[0088] The temperature control in the twin-screw extruder is as follows: 110℃ in the feeding section, 175℃ in the mixing section, 200℃ in the plasticizing section, and 180℃ in the die head.

[0089] Example 5

[0090] This embodiment provides a polylactic acid composite material, the raw material composition of which, by mass parts, includes:

[0091] Polylactic acid (molecular weight 150,000 g / mol): 50 parts;

[0092] Bio-based polycarbonate: 50 parts; wherein the bio-based component accounts for 75% by mass; the bio-based polycarbonate is isosorbide polycarbonate with a molecular weight of 200,000 g / mol and has the following structural units:

[0093]

[0094] Wherein, R1 is (CH2)4;

[0095] Impact modifier ECO-g-PMMA: 15 parts;

[0096] chain extender Arkema 4700: 0.2 copies.

[0097] The specific preparation method of this polylactic acid composite material includes the following steps:

[0098] Bio-based polylactic acid and bio-based polycarbonate were dried in a vacuum oven at 80°C for 8 hours, and impact modifier and chain extender were dried in a vacuum oven at 40°C for 8 hours.

[0099] Dried polylactic acid, bio-based polycarbonate, impact modifier, and chain extender were melt-blended in a twin-screw extruder at a screw speed of 100 rpm for 5 min to obtain a polylactic acid composite material.

[0100] The temperature control in the twin-screw extruder is as follows: 110℃ in the feeding section, 175℃ in the mixing section, 200℃ in the plasticizing section, and 180℃ in the die head.

[0101] Example 6:

[0102] This embodiment provides a polylactic acid composite material, the raw material composition of which, by mass parts, includes:

[0103] Polylactic acid (molecular weight 200,000 g / mol): 50 parts;

[0104] Bio-based polycarbonate: 50 parts; of which, the bio-based component accounts for 75% by mass.

[0105] The bio-based polycarbonate is isosorbide polycarbonate with a molecular weight of 150,000 g / mol and has the following structural units:

[0106]

[0107] Wherein, R1 is (CH2)6;

[0108] Impact modifier BPM520: 15 parts;

[0109] Chain extender Zemac E60p: 0.8 parts;

[0110] Antioxidant (Irganox B225): 0.1 parts.

[0111] The specific preparation method of the composite material includes the following steps:

[0112] Polylactic acid and bio-based polycarbonate were dried in a vacuum oven at 80°C for 8 hours, while impact modifier and chain extender were dried in a vacuum oven at 40°C for 8 hours.

[0113] Dried polylactic acid, bio-based polycarbonate, impact modifier, chain extender, and antioxidant were melt-blended in a twin-screw extruder at a screw speed of 100 rpm for 5 minutes to obtain a polylactic acid composite material.

[0114] The temperature control in the twin-screw extruder is as follows: 100℃ in the feeding section, 175℃ in the mixing section, 210℃ in the plasticizing section, and 185℃ in the die head.

[0115] Comparative Example 1

[0116] This comparative example provides a composite material, whose raw material composition, by mass parts, includes:

[0117] Polylactic acid (molecular weight 150,000 g / mol): 70 parts;

[0118] Bio-based polycarbonate (DURABIO D7340R): 30 parts; of which, the bio-based component accounts for 85% by mass.

[0119] The specific preparation method of this composite material includes the following steps:

[0120] Polylactic acid and bio-based polycarbonate were dried in a vacuum oven at 80°C for 8 hours, respectively.

[0121] The composite material can be obtained by melt-blending dried polylactic acid and bio-based polycarbonate in a twin-screw extruder at a screw speed of 100 rpm for 5 minutes.

[0122] The temperature control in the twin-screw extruder is as follows: 110℃ in the feeding section, 175℃ in the mixing section, 200℃ in the plasticizing section, and 180℃ in the die head.

[0123] Comparative Example 2

[0124] This comparative example provides a composite material, whose raw material composition, by mass parts, includes:

[0125] Polylactic acid (molecular weight 100,000 g / mol): 60 parts;

[0126] Bio-based polycarbonate (DURABIO D7340R): 40 parts; of which, the bio-based component accounts for 80% by mass.

[0127] The specific preparation method of this composite material includes the following steps:

[0128] Polylactic acid and bio-based polycarbonate were dried in a vacuum oven at 80°C for 8 hours, respectively.

[0129] The dried polylactic acid and bio-based polycarbonate are added to a twin-screw extruder and melt-blended at a screw speed of 100 rpm for 5 minutes to obtain the composite material.

[0130] The temperature control in the twin-screw extruder is as follows: 110℃ in the feeding section, 175℃ in the mixing section, 200℃ in the plasticizing section, and 180℃ in the die head.

[0131] Comparative Example 3

[0132] This comparative example provides a composite material, whose raw material composition, by mass parts, includes:

[0133] Polylactic acid (molecular weight 200,000 g / mol): 50 parts;

[0134] Bio-based polycarbonate (DURABIO D6340R): 50 parts; of which, the bio-based component accounts for 75% by mass.

[0135] The specific preparation method of this composite material includes the following steps:

[0136] Polylactic acid and bio-based polycarbonate were dried in a vacuum oven at 80°C for 8 hours, respectively.

[0137] The composite material can be obtained by melt-blending dried polylactic acid and bio-based polycarbonate in a twin-screw extruder at a screw speed of 100 rpm for 5 minutes.

[0138] The temperature control in the twin-screw extruder is as follows: 110℃ in the feeding section, 175℃ in the mixing section, 200℃ in the plasticizing section, and 180℃ in the die head.

[0139] Comparative Example 4

[0140] This comparative example provides a polylactic acid material, in which the molecular weight of the polylactic acid raw material is 120,000 g / mol.

[0141] The preparation method of this polylactic acid material includes the following steps:

[0142] Polylactic acid was vacuum dried at 80°C for 8 hours.

[0143] Polylactic acid material can be obtained by melt-blending polylactic acid in a twin-screw extruder at a screw speed of 70 rpm for 5 minutes.

[0144] The temperature control in the twin-screw extruder is as follows: 90°C in the feeding section, 170°C in the mixing section, 180°C in the plasticizing section, and 185°C in the die head.

[0145] The Vicat softening temperature (GB / T 1633-2000), elongation at break (GB / T 1040-2-2022), and notched impact strength of cantilever beam (GB / T 1843-2008) of the materials obtained in the examples and comparative examples were tested respectively, and the performance data are shown in Table 1.

[0146] Table 1

[0147] serial number Vicat softening temperature (VST, °C) Elongation at break (%) <![CDATA[Izod impact strength (kJ / m 2 )]]> Example 1 64.9 116.3 4.9 Example 2 74.1 142.5 5.6 Example 3 121.3 215 5.8 Example 4 116.4 270 8.9 Example 5 109.1 239 7.3 Example 6 110.3 98 3.6 Comparative Example 1 68.1 11.2 2.9 Comparative Example 2 81.1 13.5 3.5 Comparative Example 3 106.5 18.2 4.9 Comparative Example 4 61.2 9.1 2.3

[0148] As shown in Table 1, in some embodiments of the present invention, the Vicat softening point of the material reaches above 120°C, and its notched impact strength can reach up to 8.9 kJ / m. 2 Furthermore, the composite material of the present invention has a significantly improved elongation at break and excellent toughness.

[0149] To further characterize the phase distribution and interface structure of the compositions, scanning electron microscopy was performed on the polymers obtained in Comparative Example 2, Comparative Example 3, Example 2, and Example 4. The results are as follows: Figure 1 As shown. By Figure 1 As can be seen, adding impact modifiers and chain extenders can effectively improve the compatibility of the PLA / PC two-phase interface and refine the size of the impact-resistant dispersed phase.

[0150] The embodiments and advantages of the present invention have been described above. Finally, it should be noted that the above embodiments are merely illustrative examples and are not intended to limit the scope of protection of the present invention. Although the embodiments have described the present invention in detail, those skilled in the art should understand that various changes or modifications can be made without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions should also fall within the scope of the present invention.

Claims

1. A polylactic acid composite material, characterized in that, By weight, including: The composition comprises 50-90 parts polylactic acid, 5-50 parts bio-based polycarbonate, 5-15 parts impact modifier, and 0.1-3 parts chain extender; wherein the bio-based polycarbonate has the following structural units: R1 is selected from cyclohexenyl and -(CH2). n -, n = 0 to 6.

2. The polylactic acid composite material according to claim 1, characterized in that, By weight, including: 60-90 parts of polylactic acid, 10-50 parts of the bio-based polycarbonate, 5-10 parts of impact modifier, and 0.1-2.5 parts of chain extender.

3. The polylactic acid composite material according to claim 1, characterized in that, In the bio-based polycarbonate, the bio-based component accounts for 40% to 90% by mass.

4. The polylactic acid composite material according to claim 3, characterized in that, The bio-based component contains bisphenol A structural units derived from one or more of isosorbide, vegetable oil, and residual oil derivatives.

5. The polylactic acid composite material according to claim 1, characterized in that, The polylactic acid has a weight-average molecular weight of 80,000 to 300,000 g / mol.

6. The polylactic acid composite material according to claim 1, characterized in that, The bio-based polycarbonate has a weight-average molecular weight of 50,000-150,000 g / mol.

7. The polylactic acid composite material according to claim 1, characterized in that, The impact modifier includes polymers containing polymethyl methacrylate segments.

8. The polylactic acid composite material according to claim 7, characterized in that, The impact modifier comprises a polymer having a core-shell structure, wherein the shell material comprises a polymer containing polymethyl methacrylate segments.

9. The polylactic acid composite material according to claim 1, characterized in that, The chain extender includes ethylene-maleic anhydride copolymer and / or ethylene-acrylate-maleic anhydride copolymer.

10. The polylactic acid composite material according to claim 9, characterized in that, In the chain extender, the mass percentage of maleic anhydride structural units is 15-78%.

11. The polylactic acid composite material according to claim 1, characterized in that, The polylactic acid composite material also includes antioxidants.

12. A method for preparing a polylactic acid composite material according to any one of claims 1 to 11, characterized in that, include: Polylactic acid, bio-based polycarbonate, impact modifier, and chain extender are mixed in parts by mass to obtain a mixture, which is then processed and molded to obtain the polylactic acid composite material.

13. The preparation method according to claim 12, characterized in that, Antioxidants were also added during the preparation process.

14. The preparation method according to claim 12, characterized in that, The processing and molding method includes: extrusion granulation using a screw extruder, wherein the temperature of the feeding section is 70-110℃, the temperature of the mixing section is 165-195℃, the temperature of the plasticizing section is 175-220℃, the temperature of the die head is 175-190℃, and the screw speed is 50-100 rpm.

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