Polyurethane composition as well as preparation method and application thereof

Abstract

The invention relates to a polyurethane composition as well as a preparation method and application thereof. The polyurethane composition comprises the following components in parts by weight: 28-52 parts of thermoplastic polyurethane, 19-36 parts of polycaprolactone, 14-32 parts of polylactic acid and 5-10 parts of a plasticizer. The number average molecular weight of the polycaprolactone ranges from 48000 to 110000; the number average molecular weight of the polylactic acid is 980000 to 320000. A specific amount of polyurethane, polycaprolactone and polylactic acid are added, and the number-average molecular weight of polycaprolactone and the number-average molecular weight of polylactic acid are regulated to be within a specific range, so that a flexible wearable device product prepared from the prepared polyurethane composition not only has excellent elongation at break and high bending resistance, but also has excellent mechanical properties, and the service life of the flexible wearable device product is prolonged. And the roughness is low, and cracking is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of 3D printing materials, in particular to a polyurethane composition and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of 3D printing technology, the performance requirements of 3D printing materials are increasingly diversified. As the most widely used 3D printing technology, the core process of FDM (Fused Deposition Modeling) relies on the layer-by-layer accumulation of thermoplastic materials to print finished products. In the FDM process, the thermoplastic material (usually a 1.75mm or 2.85mm diameter round wire) is transported to the heating nozzle through the extruder, and after being melted into a semi-liquid state, it is precisely extruded from the nozzle according to the preset path. Each layer of molten wire is bonded and solidified after cooling, and the finished product is formed by layer-by-layer stacking.

[0003] The product of a flexible wearable device (such as the shell of a flexible wearable device) needs to have good flexibility and precision. When printing this type of product using FDM technology, the requirements for thermoplastic materials are higher. A low-temperature 3D printing material for bone rehabilitation braces and a preparation method thereof are disclosed in a Chinese patent. The 3D printing material has high strength and poor flexibility, making it difficult to be used for preparing the product of a flexible wearable device.

[0004] Therefore, it is urgent to find a 3D printing material that can realize the product of a flexible wearable device. SUMMARY

[0005] The primary object of the present application is to overcome the problem that the existing 3D printing materials cannot realize the product of a flexible wearable device, and to provide a polyurethane composition.

[0006] A further object of the present application is to provide a preparation method of the polyurethane composition.

[0007] Another object of the present application is to provide the application of the above-mentioned polyurethane composition in the preparation of wearable devices or moving mechanisms.

[0008] Another object of the present application is to provide a 3D printed product.

[0009] The above objects of the present application are achieved by the following technical solutions: A polyurethane composition comprising the following components in parts by weight: 28-52 parts of thermoplastic polyurethane, 19-36 parts of polycaprolactone, 14-32 parts of polylactic acid, and 5-10 parts of plasticizer. The number average molecular weight of the polycaprolactone is 48000-110000. The number average molecular weight of the polylactic acid is 98000-320000.

[0010] The inventors of this invention discovered through research that by adding specific amounts of polyurethane, polycaprolactone, and polylactic acid, and controlling the number-average molecular weight of polycaprolactone and polylactic acid within a specific range, the resulting polyurethane composition can be used to manufacture flexible wearable devices that not only have excellent elongation at break and high bending resistance, but also low roughness and no cracking.

[0011] The principle is as follows: Polyurethane, as the matrix resin, improves the elasticity of the polyurethane composition; polycaprolactone with a specific number-average molecular weight, as a flexible continuous phase, ensures the flexibility and entanglement balance of the polyurethane composition; polylactic acid with a specific number-average molecular weight, as a reinforcing phase, can maintain dimensional stability and surface smoothness; plasticizer improves processability. Through the combination of multiphase microstructure and plasticizer, not only is the elongation at break of the polyurethane composition improved and the roughness reduced, but stress dispersion can also effectively hinder crack propagation, thereby increasing the number of bending cycles and preventing cracking after extrusion.

[0012] Preferably, the polyurethane composition comprises the following components in parts by weight: 30-50 parts of thermoplastic polyurethane, 20-35 parts of polycaprolactone, 15-30 parts of polylactic acid, and 5-10 parts of plasticizer.

[0013] Preferably, the content of the thermoplastic polyurethane is more than 25 wt.% of the polyurethane composition.

[0014] Preferably, the thermoplastic polyurethane is a copolymer of diisocyanate and polymeric diol.

[0015] More preferably, the diisocyanate is at least one of aliphatic diisocyanate or aromatic diisocyanate.

[0016] More preferably, the polymeric polyol is at least one of polyester diol or polyether polyol.

[0017] Preferably, the thermoplastic polyurethane has a Shore hardness of 72 to 90 A.

[0018] More preferably, the thermoplastic polyurethane has a Shore hardness of 74 to 90 A.

[0019] More preferably, the Shore hardness of the thermoplastic polyurethane is 74-80A. Controlling the Shore hardness of the thermoplastic polyurethane within this range results in flexible parts made from the polyurethane composition having higher elongation at break and greater resistance to bending cycles.

[0020] In this invention, the Shore hardness of the thermoplastic polyurethane can be measured according to GB / T 531.1-2008.

[0021] Preferably, the melt flow rate of the thermoplastic polyurethane at 190°C and 2.16 kg is 5~20 g / 10min.

[0022] In this invention, the melt flow rate of the thermoplastic polyurethane can be measured according to GB / T 3682-2018.

[0023] Preferably, the tensile strength of the thermoplastic polyurethane is 5~30 MPa.

[0024] In this invention, the tensile strength of the thermoplastic polyurethane can be measured according to the ASTM D412 (2023 edition) standard.

[0025] Preferably, the thermoplastic polyurethane has an elongation at break of 300-900%.

[0026] In this invention, the elongation at break of the thermoplastic polyurethane can be measured according to GB / T 1040.3-2006.

[0027] Preferably, the number-average molecular weight of the polycaprolactone is 80,000 to 100,000. Controlling the number-average molecular weight of the polycaprolactone within this range results in flexible parts made from the polyurethane composition having higher elongation at break, greater resistance to bending cycles, and lower roughness.

[0028] In this invention, the number-average molecular weight of the polycaprolactone can be determined by GPC gel permeation chromatography, using tetrahydrofuran as the mobile phase and calibrated with a series of narrow-distribution polystyrene standards.

[0029] In this invention, polycaprolactone can be either commercially available or prepared in-house.

[0030] Preferably, the preparation method of polycaprolactone is as follows: a ring-opening polymerization reaction is carried out using caprolactone as a monomer.

[0031] More preferably, the ring-opening polymerization reaction is carried out at a temperature of 100~140℃ for a time of 20~72 h.

[0032] More preferably, the ring-opening polymerization reaction is carried out in the presence of a catalyst.

[0033] More preferably, the ring-opening polymerization reaction is carried out in an inert gas environment.

[0034] Preferably, the polylactic acid is at least one of L-polylactic acid or racemic polylactic acid.

[0035] Preferably, the number average molecular weight of the polylactic acid is 200,000 to 300,000; when the number average molecular weight of the polylactic acid is controlled within this range, the flexible parts made of the polyurethane composition have higher elongation at break and more bending resistance.

[0036] In this invention, the number-average molecular weight of polylactic acid can be determined by GPC gel permeation chromatography, using tetrahydrofuran as the mobile phase and calibrated with a series of narrow-distribution polystyrene standards.

[0037] In this invention, polylactic acid can be either commercially available or prepared in-house.

[0038] Preferably, polylactic acid is prepared by the following method: ring-opening polymerization of lactide as a monomer.

[0039] More preferably, the ring-opening polymerization reaction includes a first reaction stage and a second reaction stage.

[0040] More preferably, the reaction temperature of the first reaction stage is 140~160℃, the reaction time is 3~5 h, and the reaction pressure is 0.105~0.115 MPa.

[0041] More preferably, the reaction temperature of the second reaction stage is 170~190℃, the reaction time is 12~45 h, and the reaction pressure is 0.105~0.115 MPa.

[0042] More preferably, the ring-opening polymerization reaction is carried out in the presence of a catalyst.

[0043] Preferably, the plasticizer accounts for 5 to 15 wt.% of the polyurethane composition.

[0044] Preferably, the plasticizer is at least one of citrate plasticizers, polyol plasticizers, or epoxy plasticizers.

[0045] More preferably, the citrate plasticizer is at least one of tributyl citrate, triethyl citrate, or acetylated tributyl citrate.

[0046] More preferably, the polyol plasticizer is at least one of glycerol, propylene glycol, or sorbitol.

[0047] More preferably, the epoxy plasticizer is at least one of epoxidized soybean oil or epoxidized fatty acid methyl ester.

[0048] Preferably, the polyurethane composition further includes 0 to 5 parts of a lubricant.

[0049] More preferably, the lubricant is at least one of zinc stearate or ethylene bis-stearamide.

[0050] Preferably, the polyurethane composition further includes 0 to 5 parts of filler.

[0051] More preferably, the filler includes, but is not limited to, talc or calcium carbonate.

[0052] Preferably, the polyurethane composition further includes 0 to 7 parts of other additives.

[0053] More preferably, the other additives include at least one of antioxidants or light stabilizers.

[0054] Typically, the amount of antioxidant used is 0.5 to 2 parts, and the amount of light stabilizer used is 0.5 to 2 parts.

[0055] More preferably, the antioxidant is a hindered phenolic antioxidant.

[0056] Specifically, the hindered phenolic antioxidant is at least one of antioxidant 1010, antioxidant 1076, or antioxidant 1098.

[0057] More preferably, the light stabilizer is at least one of UV-531 or light stabilizer 770.

[0058] A method for preparing a polyurethane composition includes the following steps: weighing and mixing each component according to the formula, performing melt extrusion, and granulation to obtain the polyurethane composition.

[0059] Preferably, the melt extrusion is carried out in an extruder.

[0060] More preferably, the extruder is a twin-screw extruder.

[0061] More preferably, the screw speed of the extruder is 100~200 rpm and the temperature is 120~200℃.

[0062] The present invention also protects the use of the above-described polyurethane composition in the manufacture of wearable devices or active mechanisms.

[0063] Preferably, the above-described polyurethane composition is used in the preparation of flexible wearable devices or flexible motion mechanisms.

[0064] The present invention also protects a 3D printed part made from the above-described polyurethane composition using 3D printing technology.

[0065] Preferably, the 3D printed part is at least one of the following: a shell of a flexible wearable device, a flexible sensor, a connecting part of an active mechanism, or a medical protective garment.

[0066] More preferably, the housing of the flexible wearable device includes, but is not limited to, the housing of a smartwatch.

[0067] More preferably, the medical protective gear includes, but is not limited to, knee braces or wrist guards.

[0068] Compared with the prior art, the beneficial effects of the present invention are: This invention incorporates specific amounts of polyurethane, polycaprolactone, and polylactic acid, and controls the number-average molecular weight of polycaprolactone and polylactic acid within a specific range. This results in a polyurethane composition that, when used to manufacture flexible wearable devices, not only exhibits excellent elongation at break and high bending resistance, but also low roughness and resistance to cracking. Detailed Implementation

[0069] To more clearly and completely describe the technical solution of the present invention, the present invention will be further described in detail below through specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention. Various changes can be made within the scope of the claims of the present invention.

[0070] The reagents used in the various embodiments and comparative examples of this invention are described below: Thermoplastic polyurethane 1#: BASF, Elastollan® C75AW, melt flow rate of 10 g / 10min at 190°C and 2.16 kg, Shore hardness of 74 A; Thermoplastic polyurethane 2#: Dow Chemical, TPU Isoplast 302EZ, melt flow rate of 10 g / 10 min at 190°C and 2.16 kg, Shore hardness of 80 A; Thermoplastic polyurethane #3: Covestro, Texin® 985AU, melt flow rate of 10 g / 10 min at 190°C and 2.16 kg, Shore hardness of 90A; Thermoplastic polyurethane 4#: Lubrizol, ESTANE 58070 TPU, melt flow rate of 15 g / 10min at 190℃ and 2.16 kg, Shore hardness of 72A; Polycaprolactone 1#: Prepared in-house, the process is as follows: Ring-opening polymerization was carried out using ε-caprolactone as monomer and stannous octoate as catalyst at 120℃ under nitrogen atmosphere for 42 h (t1) to obtain polycaprolactone 1#. The number average molecular weight of polycaprolactone 1# is 80058; Polycaprolactone 2#: self-made, the process differs from that of polycaprolactone 1# in that: t1 is 20 h, and the number average molecular weight of the obtained polycaprolactone 2# is 50110; Polycaprolactone 3#: self-made, the process differs from that of polycaprolactone 1# in that: t1 is 72h, and the number average molecular weight of the obtained polycaprolactone 3# is 99757; Polycaprolactone 4#: self-made, the process differs from that of polycaprolactone 1# in that: t1 is 10 h, and the number average molecular weight of the obtained polycaprolactone 4# is 29983; Polycaprolactone 5#: self-made, the process differs from that of polycaprolactone 1# in that: t1 is 135h, and the number average molecular weight of the obtained polycaprolactone 5# is 150182; Polycaprolactone 6#: Pastor PCL CAPA® 6800 high molecular weight granules from France, general grade, with a number average molecular weight of 50,000; In this invention, the number-average molecular weight of polycaprolactone (GPC) can be determined by gel permeation chromatography (GPC). The GPC testing procedure is as follows: GPC is performed using a Waters ACQUITY APC™ instrument at a test temperature of 40°C. XT45, XT200, and XT459 columns are used. The solvent is tetrahydrofuran, and the mobile phase flow rate is 0.5 mL / min. Polystyrene standards are used as reference samples, and the results are taken as the average of three measurements.

[0071] Polylactic acid 1#: Self-made, the process is as follows: L-lactide was dissolved in hexanediol, and stannous octoate was added as a catalyst for ring-opening polymerization. The reaction was first carried out at a reaction temperature of 150℃ and a reaction pressure of 0.11 MPa for 4 hours (time t2), and then at a reaction temperature of 180℃ and a reaction pressure of 0.11 MPa for 28 hours (time t3). The product was then pelletized underwater, crystallized, and dried to obtain polylactic acid 1#. The number average molecular weight of polylactic acid 1# is 201897. Polylactic acid 2#: self-made, the process differs from that of polylactic acid 1# in that t3 is 12 hours, and the number average molecular weight of the obtained polylactic acid 2# is 99880; Polylactic acid 3#: self-made, the process differs from that of polylactic acid 1# in that: t3 is 45 hours, and the number average molecular weight of the obtained polylactic acid 3# is 298481; Polylactic acid 4#: self-made, the process differs from that of polylactic acid 1# in that: t3 is 5 hours, and the number average molecular weight of the obtained polylactic acid 4# is 50020; Polylactic acid 5#: self-made, the process differs from that of polylactic acid 1# in that: t3 is 72 hours, and the number average molecular weight of the obtained polylactic acid 5# is 398965; Polylactic acid 6#: NatureWorks Ingeo 2002D, USA, with a number average molecular weight of 200,000; In this invention, the number-average molecular weight of polylactic acid (PLA) can be determined by gel permeation chromatography (GPC). The GPC testing procedure is as follows: GPC is performed using a Waters ACQUITY APC™ instrument at a test temperature of 40°C. XT45, XT200, and XT459 columns are used. The solvent is tetrahydrofuran, and the mobile phase flow rate is 0.5 mL / min. Polystyrene standards are used as reference samples, and the results are taken as the average of three measurements.

[0072] Plasticizer 1#: Tributyl citrate, Aladdin, T105179; Plasticizer 2#: Epoxidized soybean oil, Aladdin, E107074; Lubricant: Zinc stearate, Shanghai Pinlan Chemical Co., Ltd., PL-101; Other additives: Antioxidant, Antioxidant 1010, commercially available; Unless otherwise specified, all components (e.g., other additives) used in the parallel examples and comparative examples are the same commercially available products.

[0073] The polyurethane compositions of the various embodiments and comparative examples of the present invention are prepared by the following process: weighing and mixing each component according to the formula, performing melt extrusion, and granulation to obtain the polyurethane composition.

[0074] The melt extrusion is carried out in a twin-screw extruder. The temperature of the twin-screw extruder is 140℃ in zone 1, 150℃ in zone 2, 160℃ in zone 3, 170℃ in zone 4, 180℃ in zone 5, 190℃ in zone 6, 190℃ in zone 7, 180℃ in zone 8, 170℃ in zone 9, and 160℃ in zone 10. The screw speed of the twin-screw extruder is 150 rpm.

[0075] The polyurethane compositions of the various embodiments and comparative examples of this invention were melt-extruded using a twin-screw extruder (extrusion temperature 200°C, screw speed 150 rpm) to produce filaments with a diameter of 1.75 mm. Using an FDM 3D printer, the filaments were heated to 220°C and printed layer by layer on a printing platform (printing temperature 220°C, printing speed 100 mm / s, layer thickness 0.4 mm) to obtain flexible parts with smooth surfaces and no obvious defects. The specifications of the flexible parts are as follows: length 150 mm, width 40 mm, height 5 mm, and shape rectangular. The performance testing methods and standards for the flexible parts are as follows: (1) Elongation at break: The flexible part is processed into type 4 specimens in the standard GB / T 1040.3-2006, and then the elongation at break is tested according to the standard GB / T 1040.3-2006. Test conditions: tensile speed is 50 mm / min.

[0076] (2) Bending resistance: The flexible part is fixed on the bending resistance tester and bent at a swing angle of 45° at room temperature. The number of bending times when the part breaks or has obvious cracks is recorded.

[0077] (3) Cracking performance test: The flexible part is subjected to 500 extrusion operations. Observe whether cracks appear on the surface of the flexible part. If cracks appear, it is recorded as "cracking"; if no cracks appear, it is recorded as "no cracking". The extrusion operation process is as follows: fix the sample on the test platform, adjust the pressure head to align with the center of the sample, set the total number of times to 500, set the extrusion force to 100N, start the extrusion cycle, and stop automatically after reaching the set number of times. Observe the sample surface with a magnifying glass (10x) and record whether cracks appear.

[0078] (4) Roughness: Five different regions of each sample were selected and line scanned using a surface roughness measuring instrument (Taylor Hobson Surtronic 3+, measurement range 0.001~800μm) to obtain the Ra value.

[0079] Examples 1-16 Examples 1-16 provide a series of polyurethane compositions, the weight parts of each component in the formulation are shown in Table 1.

[0080] Table 1 Formulations of Examples 1-16

[0081] Comparative Examples 1-9 Comparative Examples 1 to 9 provide a series of polyurethane compositions, the weight parts of each component in the formulation of which are shown in Table 2.

[0082] Table 2 Formulations of Comparative Examples 1-9

[0083] The performance test results of the 3D printing filaments of each embodiment and comparative example according to the methods mentioned above are shown in Table 3.

[0084] Table 3 Performance test results of 3D printing filaments in each embodiment and comparative example

[0085] As shown in Table 3, the polyurethane compositions of Examples 1-16 have an elongation at break of 250% or higher, a flexural strength of 400 or higher, and do not crack after 500 compressions, with a surface roughness of less than 1.5 μm. This indicates that the flexible parts made from the polyurethane compositions of the present invention not only have excellent elongation at break and high flexural strength, but also low surface roughness and do not crack.

[0086] Comparative Example 1 did not contain polycaprolactone, Comparative Example 4 used too much polycaprolactone, and the number-average molecular weight of polycaprolactone in Comparative Examples 6-7 was not suitable. The resulting flexible parts had low elongation at break, few bending cycles, cracked after 500 compressions, and high roughness.

[0087] Comparative Example 2, which did not contain polylactic acid, Comparative Example 5, which used too much polylactic acid, and Comparative Examples 8-9, which had unsuitable number-average molecular weights of polylactic acid, resulted in flexible parts with low elongation at break, low resistance to bending cycles, cracking after 500 compression cycles, and high roughness.

[0088] Comparative Example 3, without plasticizer, produced flexible parts with low elongation at break, low resistance to bending cycles, cracking after 500 compression cycles, and high roughness.

[0089] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A polyurethane composition, characterized in that, The product comprises the following components in parts by weight: 28-52 parts thermoplastic polyurethane, 19-36 parts polycaprolactone, 14-32 parts polylactic acid, and 5-10 parts plasticizer. The number-average molecular weight of the polycaprolactone is 48,000 to 110,000. The polylactic acid has a number-average molecular weight of 98,000 to 320,000.

2. The polyurethane composition according to claim 1, characterized in that, The thermoplastic polyurethane has a Shore hardness of 72~90A.

3. The polyurethane composition according to claim 1, characterized in that, The number-average molecular weight of the polycaprolactone is 80,000 to 100,000.

4. The polyurethane composition according to claim 1, characterized in that, The polylactic acid has a number average molecular weight of 200,000 to 300,000.

5. The polyurethane composition according to claim 1, characterized in that, The plasticizer is at least one of citrate ester plasticizers, polyol plasticizers, or epoxy plasticizers.

6. The polyurethane composition according to claim 1, characterized in that, The polyurethane composition also includes 2 to 5 parts of lubricant.

7. The polyurethane composition according to claim 1, characterized in that, The polyurethane composition also includes 0 to 7 parts of other additives.

8. A method for preparing the polyurethane composition according to claims 1-7, characterized in that, The process includes the following steps: weighing and mixing each component according to the formula, performing melt extrusion, and granulation to obtain the polyurethane composition.

9. The use of the polyurethane composition according to claims 1 to 7 in the preparation of flexible wearable devices or active mechanisms.

10. A 3D printed part, characterized in that, The polyurethane composition according to any one of claims 1 to 7 is prepared using 3D printing technology.

Images