High-toughness high-heat-resistance polylactic acid composite material for 3D printing and preparation method of high-toughness high-heat-resistance polylactic acid composite material

Abstract

The invention discloses a high-toughness and high-heat-resistance polylactic acid composite material for 3D printing and a preparation method of the high-toughness and high-heat-resistance polylactic acid composite material. The high-toughness and high-heat-resistance polylactic acid composite material is prepared from the following raw materials: poly-L-lactic acid, poly-D-lactic acid, a grafted rubber elastomer and a nucleating agent. The 3D printing material has the beneficial effects that the nucleating agent and the rubber elastomer are added in the technical scheme, so that the formed stereocomplex polylactic acid crystals are more uniform, the size deformation and warping caused by non-uniform crystallization in the 3D printing process are reduced, the notch impact strength of the blend is further improved, and on the basis, the 3D printing material has good mechanical properties. And in the form of preparing the master batch, the materials can be further dispersed, and the finally obtained performance is more excellent.

Description

Technical Field

[0001] This invention relates to the field of composite material preparation technology, and in particular to a high-toughness and high-heat-resistant polylactic acid composite material for 3D printing and its preparation method. Background Technology

[0002] Currently, additive manufacturing is one of the main driving forces. Additive manufacturing, also known as 3D printing, integrates many cutting-edge technologies such as materials science, electrical control technology, digital technology, and information science. Compared to traditional manufacturing methods such as injection molding and casting, 3D printing has advantages such as high-precision manufacturing of complex structures, saving materials and time, high design freedom, and personalized customization, constantly pushing the limits of product design, manufacturing, and usage, bringing new development opportunities to traditional manufacturing industries. Among them, fused deposition modeling (FDM) technology, which does not rely on lasers but instead heats and melts various thermoplastic filaments to build up shapes, has been widely used in the civilian sector due to its ease of operation and high cost-effectiveness. CN104910598 discloses an ultra-tough and highly heat-resistant polylactic acid / elastomer blend material or product and its preparation method, comprising 75-99 parts of L- or D-polylactic acid, 1-25 parts of D- or L-polylactic acid as the third component, and 5-30 wt% of elastomer based on the total amount of polylactic acid. The resulting blend material or product has a crystallinity of 43-53%, a heat resistance temperature of 113.5-140.5℃, and a notched impact strength of 20.5-93.3 kJ / m².

[0003] CN113717510 discloses an ultra-tough and heat-resistant polylactic acid / rubber alloy and its preparation method. The polylactic acid / rubber alloy is prepared by melt blending L-polylactic acid, D-polylactic acid and rubber particles. The resulting matrix has a crystallinity of 48.6-51.1%, a heat resistance temperature of 132.3-139.8℃, and a notched impact strength of 21.3-84.9 kJ / m².

[0004] Commonly used FDM 3D printing polymer materials include PLA, ABS, PETG, and TPU. Among them, polylactic acid (PLA) is the most commonly used 3D printing material. Its advantages are that it has no unpleasant odor when melted, and it is derived from biomass raw materials such as corn and is completely biodegradable. However, it also has disadvantages such as poor toughness and poor heat resistance, which greatly limits the performance and application of printed objects. Currently, there are some specific cases of improvement schemes for PLA's poor toughness and heat resistance. However, most of these cases suffer from warping and deformation during the printing process due to issues such as its crystallization rate, making it unsuitable for use in the 3D printing field. This patent proposes an improvement scheme that not only improves the heat resistance of PLA but also enhances its toughness, allowing it to be better applied in the 3D printing field and reducing dimensional deformation during the printing process. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned problems by designing a high-toughness and high-heat-resistant polylactic acid composite material for 3D printing and its preparation method.

[0006] The technical solution of the present invention to achieve the above objectives is a high-toughness, high-heat-resistant polylactic acid composite material for 3D printing. The raw materials for preparing the high-toughness, high-heat-resistant polylactic acid composite material are as follows: L-polylactic acid (PLLA), D-polylactic acid (PDLA), grafted rubber elastomer, and nucleating agent. The chemical structural formula of the high-toughness, high-heat-resistant polylactic acid composite material is as follows:

[0007] As a further description of this technical solution, the raw materials for preparation are composed of the following parts by weight: 50-95 parts of polylactic acid (PLLA), 5-50 parts of polylactic acid (PDLA), 5-15 parts of grafted rubber elastomer, and 5-15 parts of nucleating agent.

[0008] As a further description of this technical solution, the grafted rubber elastomer is an ethylene vinyl acetate copolymer, using EVA or EVM.

[0009] As a further description of this technical solution, the nucleating agent is an acylhydrazine-based nucleating agent, specifically TMC-300.

[0010] A method for preparing a high-toughness, high-heat-resistant polylactic acid composite material for 3D printing includes the following steps: Step 1: Weighing operation; Step 2: Mixing operation; Step 3: Granulation process; Step 4: Drying operation; Step 5: Extrusion operation; Step Six: Split Volume Operation; Step 7: Performance testing.

[0011] In step one, the raw materials for preparing the high-toughness and high-heat-resistant polylactic acid composite material are weighed.

[0012] In step two, polylactic acid (PLA), polylactic acid (PLA), grafted rubber elastomer, and nucleating agent are mixed in a high-speed mixer to ensure complete dispersion of each component. The mixing temperature is 150-200℃.

[0013] In step three, granulation is carried out using a twin-screw extruder, with a blending temperature of 160-190℃.

[0014] In step four, the extruded granules are placed in a drying oven to dry at a temperature of 50-100℃ for 6-12 hours. In step five, the dried granules are placed in a single-screw extruder for extrusion at a temperature of 160-200℃. The granules are then cooled by a water-cooling tank and an air-cooling machine to produce wires with a diameter of 1.75mm. In step six, the wires are slit by a spooler, dried, and finally sealed for storage.

[0015] In step seven, the dried filament is tested for printing performance and mechanical properties using a 3D printer. The printing temperature is 180℃-230℃, the printing speed is 50-200mm / s, and the base plate temperature does not need to be set.

[0016] Its beneficial effects are that the high-toughness and high-heat-resistant polylactic acid composite material prepared by this technical solution for 3D printing not only retains the high strength, high toughness and high heat resistance of stereocomposite polylactic acid, but also improves the shortcomings of printing warping and dimensional deformation caused by the original high crystallization rate for the application field of 3D printing. It provides a new idea for the realization of high-heat-resistant and high-toughness PLA 3D printing and also broadens the application fields of PLA in the future.

[0017] This technical solution incorporates nucleating agents and rubber elastomers, which not only make the formed stereocomposite polylactic acid crystals more uniform, reducing dimensional deformation and warping caused by uneven crystallization during 3D printing, but also further improve the notched impact strength of the blend. On this basis, by preparing masterbatch, the material can be further dispersed, resulting in better performance. Detailed Implementation

[0018] First, let me explain the design intention of this invention. Commonly used FDM 3D printing polymer materials include PLA, ABS, PETG, and TPU. Among them, polylactic acid (PLA) is the most commonly used 3D printing material. Its advantages are that it has no unpleasant odor when melted, and it is derived from biomass raw materials such as corn and can be completely degraded. However, it also has disadvantages such as poor toughness and poor heat resistance, which greatly limits the performance and application of printed objects. At present, there are some specific cases of improvement schemes for PLA's poor toughness and heat resistance. However, most cases have problems such as warping and deformation during the printing process due to issues such as its crystallization rate, which prevents it from being well applied in the field of 3D printing. Therefore, this invention designs a high-toughness and high-heat-resistant polylactic acid composite material for 3D printing and its preparation method.

[0019] The present invention will now be described in detail, providing a high-toughness, high-heat-resistant polylactic acid composite material for 3D printing. The raw materials for preparing the high-toughness, high-heat-resistant polylactic acid composite material are as follows: L-polylactic acid (PLLA), D-polylactic acid (PDLA), grafted rubber elastomer, and nucleating agent. The raw materials are composed of the following parts by weight: 50-95 parts of L-polylactic acid (PLLA), preferably 65 parts; 5-50 parts of D-polylactic acid (PDLA), preferably 25 parts; 5-15 parts of grafted rubber elastomer; and 5-15 parts of nucleating agent.

[0020] The chemical structural formula of the high-toughness and high-heat-resistant polylactic acid composite material is as follows:

[0021] The grafted rubber elastomer is an ethylene vinyl acetate copolymer, using EVA or EVM, with an addition amount preferably of 3-15 parts, more preferably 5 parts. The nucleating agent is an acylhydrazine nucleating agent, using TMC-300, with an addition amount preferably of 5-15 parts, more preferably 5 parts.

[0022] The following describes the preparation method of high-toughness and high-heat-resistant polylactic acid composite materials for 3D printing, including the following steps: Step 1: Weighing operation; In Step 1, the raw materials for preparing high-toughness and high-heat-resistant polylactic acid composite materials are weighed.

[0023] Step 2: Mixing operation; In step 2, L-polylactic acid, D-polylactic acid, grafted rubber elastomer, and nucleating agent are mixed in a high-speed mixer to ensure complete dispersion of each component. The mixing temperature is 150-200℃.

[0024] Step 3: Granulation process; In step 3, granulation is carried out by a twin-screw extruder. The blending temperature of the twin-screw extruder is preferably 160-190℃, more preferably 180℃.

[0025] Step 4: Drying operation; In step 4, the extruded granules are placed in a drying oven for drying. The temperature inside the drying oven is 50-100℃, preferably 80-100℃, and the drying time is 6-12 hours, preferably 8 hours.

[0026] Step 5: Extrusion operation; In step 5, the dried granules are placed in a single-screw extruder for extrusion at 180°C. The single-screw extrusion temperature is preferably 160-200°C, more preferably 180°C. The granules are cooled by a water cooling tank and an air cooler to produce wires with a diameter of 1.75 mm.

[0027] Step Six: Rewinding Operation; In Step Six, the wire is rewound using a slitting machine, dried, and finally sealed for storage.

[0028] Step 7: Performance testing. In step 7, the dried filament is tested for printing performance and mechanical properties using a 3D printer. The printing temperature is 180℃-230℃, the printing speed is 50-200mm / s, and the base plate temperature does not need to be set.

[0029] The following will describe the details with reference to the embodiments: Example 1 The preparation method of high-toughness and high-heat-resistant polylactic acid composite materials for 3D printing includes the following steps: (1) Weigh the dried PLLA, PDLA, EVA rubber elastomers and nucleating agent in a ratio of 50 / 40 / 5 / 5 and mix them in a high-speed mixer; (2) After the particles from (1) are mixed evenly, they are granulated by a twin-screw extruder. The temperatures of each zone of the twin-screw extruder are set to 130℃, 150℃, 170℃, 180℃, 180℃, 180℃, 180℃, 180℃, 180℃, 180℃, 180℃. (3) Place the granules prepared in (2) in a drying oven at 80-100℃ and dry for 8 hours; (4) The dried material from (3) is extruded in a single-screw extruder. The temperatures of each zone of the extruder are 150℃, 170℃, 180℃, 180℃, 180℃, and 180℃. The material is cooled by a water cooling tank and an air cooler to produce wire with a diameter of 1.75mm. The wire is then spun by a slitting machine, dried, and finally sealed for storage. (5) Test the printing performance and mechanical properties of the dried filament (4) using a 3D printer. The printing temperature is 180℃-230℃ and the printing speed is 50-200mm / s. The base plate temperature does not need to be set.

[0030] Example 2 The preparation method of high-toughness and high-heat-resistant polylactic acid composite materials for 3D printing includes the following steps: (1) Weigh the dried PLLA, PDLA, EVA rubber elastomers and nucleating agent in a ratio of 65 / 25 / 5 / 5 and mix them in a high-speed mixer; (2) After the particles from (1) are mixed evenly, they are granulated by a twin-screw extruder. The temperatures of each zone of the twin-screw extruder are set to 130℃, 150℃, 170℃, 180℃, 180℃, 180℃, 180℃, 180℃, 180℃, 180℃, 180℃. (3) Place the granules prepared in (2) in a drying oven at 80-100℃ and dry for 8 hours; (4) The dried material from (3) is extruded in a single-screw extruder. The temperatures of each zone of the extruder are 150℃, 170℃, 180℃, 180℃, 180℃, and 180℃. The material is cooled by a water cooling tank and an air cooler to produce wire with a diameter of 1.75mm. The wire is then spun by a slitting machine, dried, and finally sealed for storage. (5) Test the printing performance and mechanical properties of the dried filament (4) using a 3D printer. The printing temperature is 180℃-230℃ and the printing speed is 50-200mm / s. The base plate temperature does not need to be set.

[0031] Example 3 The preparation method of high-toughness and high-heat-resistant polylactic acid composite materials for 3D printing includes the following steps: (1) Weigh the dried PLLA, PDLA, EVA rubber elastomers and nucleating agent in a ratio of 85 / 5 / 5 / 5 and mix them in a high-speed mixer; (2) After the particles from (1) are mixed evenly, they are granulated by a twin-screw extruder. The temperatures of each zone of the twin-screw extruder are set to 130℃, 150℃, 170℃, 180℃, 180℃, 180℃, 180℃, 180℃, 180℃, 180℃, 180℃. (3) Place the granules prepared in (2) in a drying oven at 80-100℃ and dry for 8 hours; (4) The dried material from (3) is extruded in a single-screw extruder. The temperatures of each zone of the extruder are 150℃, 170℃, 180℃, 180℃, 180℃, and 180℃. The material is cooled by a water cooling tank and an air cooler to produce wire with a diameter of 1.75mm. The wire is then spun by a slitting machine, dried, and finally sealed for storage. (5) Test the printing performance and mechanical properties of the dried filament (4) using a 3D printer. The printing temperature is 180℃-230℃ and the printing speed is 50-200mm / s. The base plate temperature does not need to be set.

[0032] Example 4 The preparation method of high-toughness and high-heat-resistant polylactic acid composite materials for 3D printing includes the following steps: (1) Weigh the dried PLLA, PDLA, EVM rubber elastomers and nucleating agent in a ratio of 65 / 25 / 5 / 5 and mix them in a high-speed mixer; (2) After the particles from (1) are mixed evenly, they are granulated by a twin-screw extruder. The temperatures of each zone of the twin-screw extruder are set to 130℃, 150℃, 170℃, 180℃, 180℃, 180℃, 180℃, 180℃, 180℃, 180℃, 180℃. (3) Place the granules prepared in (2) in a drying oven at 80-100℃ and dry for 8 hours; (4) The dried material from (3) is extruded in a single-screw extruder. The temperatures of each zone of the extruder are 150℃, 170℃, 180℃, 180℃, 180℃, and 180℃. The material is cooled by a water cooling tank and an air cooler to produce wire with a diameter of 1.75mm. The wire is then spun by a slitting machine, dried, and finally sealed for storage. (5) Test the printing performance and mechanical properties of the dried filament (4) using a 3D printer. The printing temperature is 180℃-230℃ and the printing speed is 50-200mm / s. The base plate temperature does not need to be set.

[0033] Example 5 The preparation method of high-toughness and high-heat-resistant polylactic acid composite materials for 3D printing includes the following steps: (1) Weigh the dried PLLA and EVM rubber elastomers at a ratio of 65 / 5, and weigh the PDLA and nucleating agent at a ratio of 25 / 5 respectively, and put them into a high-speed mixer for mixing; (2) After the two groups of particles in (1) are mixed evenly, they are granulated by a twin-screw extruder. The temperature of each zone of the twin-screw extruder is set to 130℃, 150℃, 170℃, 180℃, 180℃, 180℃, 180℃, 180℃, 180℃, 180℃, 180℃, 180℃. (3) Place the two groups of particles prepared in (2) in a drying oven at 80-100℃ and dry for 8 hours; (4) Mix the dried material from (3) at a weight ratio of 7 / 3 and extrude it in a single-screw extruder. The temperatures of each zone of the extruder are 150℃, 170℃, 180℃, 180℃, 180℃, and 180℃. The material is cooled by a water cooling tank and an air cooler to produce wire with a diameter of 1.75mm. The wire is then slit by a slitting machine, dried, and finally sealed for storage. (5) Test the printing performance and mechanical properties of the dried filament (4) using a 3D printer. The printing temperature is 180℃-230℃ and the printing speed is 50-200mm / s. The base plate temperature does not need to be set.

[0034] Example 6 The preparation method of high-toughness and high-heat-resistant polylactic acid composite materials for 3D printing includes the following steps: (1) Weigh the dried PLLA and EVA rubber elastomers at a ratio of 65 / 5, and weigh the PDLA and nucleating agent at a ratio of 25 / 5 respectively, and put them into a high-speed mixer for mixing; (2) After the two groups of particles in (1) are mixed evenly, they are granulated by a twin-screw extruder. The temperature of each zone of the twin-screw extruder is set to 130℃, 150℃, 170℃, 180℃, 180℃, 180℃, 180℃, 180℃, 180℃, 180℃, 180℃, 180℃. (3) Place the two groups of particles prepared in (2) in a drying oven at 80-100℃ and dry for 8 hours; (4) Mix the dried material from (3) at a weight ratio of 7 / 3 and extrude it in a single-screw extruder. The temperatures of each zone of the extruder are 150℃, 170℃, 180℃, 180℃, 180℃, and 180℃. The material is cooled by a water cooling tank and an air cooler to produce wire with a diameter of 1.75mm. The wire is then slit by a slitting machine, dried, and finally sealed for storage. (5) Test the printing performance and mechanical properties of the dried filament (4) using a 3D printer. The printing temperature is 180℃-230℃ and the printing speed is 50-200mm / s. The base plate temperature does not need to be set.

[0035] Comparative Example 1 Unlike Example 1, no rubber elastomer and nucleating agent were added, while other raw materials and preparation processes remained unchanged.

[0036] Comparative Example 2 Unlike Example 2, no rubber elastomer and nucleating agent were added, while other raw materials and preparation processes remained unchanged.

[0037] Comparative Example 3 Unlike Example 3, no rubber elastomer and nucleating agent were added, while other raw materials and preparation processes remained unchanged.

[0038] Comparative Example 4 Unlike Example 4, no rubber elastomer and nucleating agent were added, while other raw materials and preparation processes remained unchanged.

[0039] Comparative Example 5 Unlike Example 5, no rubber elastomer and nucleating agent were added, while other raw materials and preparation processes remained unchanged.

[0040] Comparative Example 6 Unlike Example 6, no rubber elastomer and nucleating agent were added, while other raw materials and preparation processes remained unchanged.

[0041] The following tables will show the tensile strength, elongation at break, flexural strength, flexural modulus, unnotched impact strength, notched impact strength, tensile modulus, Z-axis strength test, Vicat softening temperature, heat distortion temperature, block test, sag test, tilt angle test, printing accuracy test, wire drawing test, and warpage test of the examples and comparative examples.

[0042] Table 1 Test Tables for Examples 1-6 Table 2 Test Tables for Comparative Examples 1-6 The dextrorotatory polylactic acid in this technical solution is high molecular weight dextrorotatory polylactic acid, but it can also be replaced with low molecular weight dextrorotatory polylactic acid. The grafted rubber elastomer is an active group rubber elastomer, which can also be replaced with a conventional rubber elastomer, but the performance will be slightly reduced.

[0043] The high-toughness and high-heat-resistant polylactic acid composite material prepared by this technical solution for 3D printing not only retains the high strength, high toughness and high heat resistance of stereocomposite polylactic acid, but also improves the printing warping and dimensional deformation caused by the original high crystallization rate for the 3D printing application field. It provides a new idea for realizing high-heat-resistant and high-toughness PLA 3D printing and also broadens the future application fields of PLA.

[0044] This technical solution incorporates nucleating agents and rubber elastomers, which not only make the formed stereocomposite polylactic acid crystals more uniform, reducing dimensional deformation and warping caused by uneven crystallization during 3D printing, but also further improve the notched impact strength of the blend. On this basis, by preparing masterbatch, the material can be further dispersed, resulting in better performance.

[0045] The above technical solutions only embody the preferred technical solutions of the present invention. Any modifications that may be made by those skilled in the art to certain parts thereof embody the principles of the present invention and fall within the protection scope of the present invention.

Claims

1. A high-toughness and high-heat-resistance polylactic acid composite material for 3D printing, characterized by, The raw materials for preparing the high-toughness and high-heat-resistance polylactic acid composite material are as follows: left-handed polylactic acid, right-handed polylactic acid, grafted rubber elastomer, nucleating agent, and the chemical structural formula of the high-toughness and high-heat-resistance polylactic acid composite material is as follows: 。 2.The high-toughness and high-heat-resistance polylactic acid composite material for 3D printing of claim 1, wherein, The raw materials are composed of 50-95 parts of left-handed polylactic acid, 5-50 parts of right-handed polylactic acid, 3-15 parts of grafted rubber elastomer, and 5-15 parts of nucleating agent. 3.The high-toughness and high-heat-resistance polylactic acid composite material for 3D printing of claim 1, wherein, The grafted rubber elastomer is ethylene-vinyl acetate copolymer, and EVA or EVM is used. 4.The high-toughness and high-heat-resistance polylactic acid composite material for 3D printing of claim 1, wherein, The nucleating agent is hydrazide nucleating agent, and TMC-300 is used.

5. A method for preparing a high-toughness and high-heat-resistance polylactic acid composite material for 3D printing according to any one of claims 1-4, characterized in that, The method comprises the following steps: Step one: weighing operation; Step two: mixing operation; Step three: granulation process; Step four: drying operation; Step five: extrusion operation; Step six: roll division operation; Step seven: performance test operation. 6.The method for preparing a high-toughness and high-heat-resistance polylactic acid composite material for 3D printing according to claim 5, characterized in that, In the step one, the raw materials for preparing the high-toughness and high-heat-resistance polylactic acid composite material are weighed. 7.The method for preparing a high-toughness and high-heat-resistance polylactic acid composite material for 3D printing according to claim 5, characterized in that, In the step two, the left-handed polylactic acid, right-handed polylactic acid, grafted rubber elastomer, and nucleating agent are mixed in a high-speed mixer to make the components fully dispersed, and the blending temperature is 150-200℃. 8.The method for preparing a high-toughness and high-heat-resistance polylactic acid composite material for 3D printing according to claim 5, characterized in that, In the step three, the granulation is performed by a double-screw extruder, and the blending temperature of the double-screw extruder is 160-190℃. 9.The method for preparing a high-toughness and high-heat-resistance polylactic acid composite material for 3D printing according to claim 5, characterized in that, In the step four, the granules prepared by the extruder are dried in a drying box, the temperature in the drying box is 50-100℃, and the drying time is 6-12h. 10.The method for preparing a high-toughness and high-heat-resistance polylactic acid composite material for 3D printing according to claim 5, characterized in that, In the step five, the dried granules are extruded in a single-screw extruder, the extrusion temperature of the single-screw extruder is 160-200℃, and the granules are cooled by a water cooling tank and an air cooling machine to prepare a 1.75mm diameter wire. In the step six, the wire is rolled by a roll division machine, dried, and finally plastic-sealed and stored. In the step seven, the dried wire is printed by a 3D printer to test the printing performance and mechanical properties, the printing temperature is 180-230℃, the printing speed is 50-200mm / s, and the bottom plate temperature does not need to be set.

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