Polymer capable of realizing FDM printing interlayer defect self-repairing and use method thereof

Abstract

The invention discloses a polymer capable of realizing FDM printing interlayer defect self-repairing and a use method thereof. Comprising the following steps: synthesizing a self-repairing polymer by taking polypropylene glycol and isophorone diisocyanate as raw materials and adipic dihydrazide and 2, 2-diaminodiphenyl disulfide as chain extenders; the polymer material has excellent self-repairing performance, mechanical strength and ductility. An FDM fused deposition heating extrusion type printer is used, the self-repairing polymer serves as a printing material for printing, the material can repair FDM printing interlayer defects through the self-repairing capacity of the material, and the mechanical strength of the material is effectively improved and kept.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing materials, and in particular to a polymer capable of self-repairing defects between FDM printing layers and a method for using the polymer. Background Art

[0002] FDM (Fused Deposition Modeling) is a type of additive manufacturing. Based on the principle of extrusion, FDM is widely used and low-cost. However, the problem of interlayer defects in FDM printing is very difficult, and the mechanical strength of printed objects is greatly reduced. The disappointing interlayer adhesion produced by FDM often leads to poor mechanical properties, which has become a technical bottleneck in industrial production. Many scholars are committed to studying the impact of interlayer defects in FDM printing technology on mechanical properties. Currently, the materials that are more commonly used for printing include hydrogels and polyurethanes. Due to their excellent properties, self-healing materials have also been discovered by researchers and gradually developed for use in the field of 3D printing.

[0003] A search of existing technical literature revealed that the FDM printing materials currently on the market cannot solve the problem of poor mechanical properties caused by interlayer defects in FDM. Most research content reduces the impact of interlayer defects from the perspective of printing process and printing parameters. Wang Jun et al. compared several different TPU materials, and the ductility was only about 600%, and the printing temperature was as high as over 230°C. The printed materials had many defects and poor precision. Ritzen, L et al. studied a self-healing thermoplastic polyurethane material for FDM printing, and the printing temperature required was around 230°C. At this temperature, the printed samples themselves had many defects. Summary of the Invention

[0004] The purpose of the present invention is to provide a polymer that can realize self-repair of interlayer defects in FDM printing and a method of using the same, so as to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A polymer capable of self-repairing defects between FDM printing layers has the following structure:

[0007]

[0008] Wherein, m and n are the number of repeating units, m ranges from 6 to 40, and n ranges from 30 to 40.

[0009] The method for preparing the self-healing polymer comprises the following steps:

[0010] (1) Polypropylene glycol (PPG) is subjected to vacuum treatment at 85-150°C for 1-3 hours to eliminate air and moisture inside, and then filled with nitrogen for protection;

[0011] (2) After lowering the temperature to 70-85°C, a DMF solution of isophorone diisocyanate (IPDI) is added dropwise to the treated polypropylene glycol, and then a small amount of dibutyltin dilaurate is added dropwise. After the addition is completed, the prepolymerization reaction is stirred for a period of time. During the reaction, the molar ratio of polypropylene glycol to isophorone diisocyanate is controlled to be 1:3;

[0012] (3) lowering the temperature to 40-70° C. again, adding a DMF solution of a chain extender to the system of step (2), stirring the chain extension reaction for a period of time after the addition is completed, and obtaining the target product after drying, wherein the chain extender is adipic acid dihydrazide (ADH) and 2,2-diaminodiphenyl disulfide (DTDA).

[0013] As a further embodiment of the present invention, the mass of dibutyltin dilaurate is 0.1 to 0.2 g.

[0014] As a further embodiment of the present invention, the prepolymerization reaction is stirred for more than 3 hours after the dropwise addition is completed.

[0015] As a further embodiment of the present invention, the chain extension reaction is stirred for more than 16 hours after the dropwise addition is completed.

[0016] As a further embodiment of the present invention, the molar ratio of the total molar amount of the chain extender to PPG is 2:1, and the molar proportion of DTDA in the chain extender is greater than 50%, preferably 60-90%.

[0017] As a further solution of the present invention, after the dropwise addition is completed, the chain extension reaction is stirred for a period of time, and the target product is obtained after drying. The drying temperature is 40-80° C. and the drying time is 1-2 days.

[0018] The present invention also provides the use of the self-healing polymer as a fused deposition type 3D printing material.

[0019] As a further solution of the present invention, a fused deposition type heated extrusion 3D printer is used, and the printing parameters are set. The printing temperature is set to 90-140°C, and the platform cooling temperature is set to room temperature 25°C; the extrusion nozzle diameter is selected to be 0.4-2mm; the layer height is set to 0.1-1mm, and the default extrusion width is 0.1-1mm; the filling density is 100%, the nozzle movement speed is set, and the layer height is limited to 0.1-2mm.

[0020] As a further solution of the present invention, after printing is completed, the sample is allowed to cool for 1 to 3 minutes and then placed in an oven at 60 to 80°C for 1 to 2 days for defect repair. The internal defects and interlayer gaps caused by FDM fused deposition printing can be repaired within 1 to 2 days.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) By utilizing the synergistic effect of hydrogen bonds and disulfide bonds, the self-healing polymer material has good self-healing properties, while also having excellent mechanical properties and ductility. This allows it to maintain its own mechanical strength while being able to repair interlayer defects when used as an FDM printing material. Its interlayer defect repair can increase the mechanical strength of FDM-printed splines from 1.5MPa to 4.05MPa, greatly enhancing the mechanical strength of the printed object.

[0023] (2) In the present invention, the ASCZ structure composed of adipic acid dihydrazide and polypropylene glycol provides abundant hydrogen bonding sites, and the high hydrogen bonding density helps enhance the mechanical properties of the material. With the addition of disulfide bonds provided by 2,2-diaminodiphenyl disulfide, its breakage and recombination can increase the mobility of the chain segments, thereby enhancing the self-healing properties of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 These are infrared spectra of the polymers PPG-A-75% SS, PPG-A-50% SS, PPG-A-25% SS, PPG-A, and PPG-SS of Examples 1 to 5 of the present invention.

[0025] Figure 2 The NMR spectra of the polymers prepared in Examples 1 to 5 of the present invention are shown.

[0026] Figure 3 The Raman spectra of the polymers prepared in Examples 1 to 5 of the present invention are shown.

[0027] Figure 4 The XRD spectra of the polymers prepared in Examples 1 to 5 of the present invention are shown.

[0028] Figure 5 These are TGA charts of the polymers prepared in Examples 1 to 5 of the present invention.

[0029] Figure 6 These are AFM images of the polymers prepared in Examples 1 to 5 of the present invention.

[0030] Figure 7 This is a tensile property test of the polymers prepared in Examples 1 to 5 of the present invention.

[0031] Figure 8 The repair tensile performance tests of the polymers prepared in Examples 1, 2, and 5 of the present invention are shown in Figures a and b, respectively, for the repair tensile test of PPG-SS at 60°C, and c, respectively, for the repair tensile test of PPG-A-75% SS at 60°C.

[0032] Figure 9This is a repair tensile property test of the polymers prepared in Examples 3 and 4 of the present invention, wherein a is a repair tensile test of PPG-A-25% SS at 100°C, and b is a tensile test of PPG-A at 100°C.

[0033] Figure 10 This is a microscope scratch repair test of Example 5 of the present invention, wherein a is the original scratch microscope image, and b is the image after repair at 60°C.

[0034] Figure 11 This is a microscope scratch repair test of Example 1 of the present invention, wherein a is the original scratch microscope image, and b is the image after repair at 60°C.

[0035] Figure 12 This is a rheological property test of the PPG-A-75% SS polymer prepared in Example 1 of the present invention, wherein a is the viscosity change curve of PPG-A-75% SS at 20°C to 160°C, and b is the viscosity of PPG-A-75% SS at 130°C and 1 to 100 Hz.

[0036] Figure 13 This is a photo of the PPG-A-75% SS polymer prepared in Example 1 of the present invention being extruded into filaments by a printer, wherein a is a photo of the filaments just extruded, and b is a photo of the filament material.

[0037] Figure 14 Microscopic repair images of interlayer gaps and defects of two square sheets of PPG-A-75% SS polymer prepared in Example 1 of the present invention were printed by a printer, wherein a is the printed microscopic image of the two square sheets, and b to h are microscopic repair images of the sheets repaired at 60°C for 12 hours, 24 hours, 36 hours, 72 hours, 4 days, 8 days, and 12 days, respectively. DETAILED DESCRIPTION

[0038] The technical solution of the present invention will be further described in detail below in conjunction with specific implementation methods.

[0039] The present invention provides a method for preparing a polymer capable of self-repairing defects between FDM printing layers, comprising the following steps:

[0040] Weigh a certain mass of polypropylene glycol material, perform vacuum treatment at 85-150°C, vacuum for 1-3 hours until there is no air and moisture inside, and then fill with nitrogen for protection.

[0041] After lowering the temperature to 70-85°C, weigh a certain amount of isophorone diisocyanate (DII) in DMF and slowly add it dropwise using a syringe. Add 0.1-0.2g of dibutyltin dilaurate as a catalyst. Stir the prepolymerization reaction for at least 3 hours after the addition is complete. During the reaction, control the molar ratio of polypropylene glycol to isophorone diisocyanate to be 1:3.

[0042] The temperature was lowered again to 40-70° C., and a chain extender was added dropwise. After the addition was completed, the chain was stirred for more than 16 hours, and the target product was obtained after drying. The chain extender was a DMF solution of adipic acid dihydrazide (ADH) and a DMF solution of 2,2-diaminodiphenyl disulfide (DTDA).

[0043] The molar ratio of the total molar amount of the chain extender to PPG is 2:1, and the molar proportion of DTDA in the chain extender is greater than 50%, preferably 60-90%.

[0044] The sample after the reaction is completed is poured into a polytetrafluoroethylene (PTFE) mold and dried at 40-80°C for 1-2 days to obtain the final self-healing polymer.

[0045] Its synthetic route is as follows:

[0046]

[0047] Use a fused deposition model heated extrusion 3D printer and set the printing parameters. Set the printing temperature to 90-140°C and the platform cooling temperature to room temperature (25°C). Select an extrusion nozzle diameter of 0.4-2mm. Set the layer height to 0.1-1mm and the default extrusion width to 0.1-1mm. Set the infill density to 100%, set the nozzle speed, and limit the layer height to 0.1-2mm.

[0048] Add the self-healing polymer to the heating sleeve, set the heating temperature, and wait for the temperature to rise and stabilize before lowering the nut. Once the self-healing material is flowing steadily from the nozzle, select the print file and begin printing.

[0049] After printing is complete, wait for the sample to cool for 1-3 minutes before removing it. Place the sample in an oven for defect repair. Repairs can be completed within 1-2 days, significantly improving the mechanical properties of the object.

[0050] Example 1

[0051] A method for preparing a polymer capable of self-repairing interlayer defects in FDM printing, comprising the following steps:

[0052] S1. Weigh 4 g of polypropylene glycol and subject it to a vacuum treatment at 120°C for 2 hours to remove air and moisture from the interior, followed by nitrogen protection.

[0053] S2. After lowering the temperature to 80°C, weigh 1.4004 g of isophorone diisocyanate, dissolve it in DMF, and slowly add it dropwise using a syringe. The molar ratio of polypropylene glycol to isophorone diisocyanate is 1:3.

[0054] S3. Add 0.1 g of dibutyltin dilaurate dropwise for catalysis, and stir the prepolymerization reaction for 3 hours.

[0055] In step S4, lower the temperature again to 60°C, weigh 0.174 g of adipic acid dihydrazide, dissolve it in DMF, weigh 0.7451 g of 2,2-diaminodiphenyl disulfide, dissolve it in DMF, and slowly add it dropwise to the reaction solution in step S2. Incubate the chain extension reaction at 60°C for 24 hours. The molar ratio of DTDA to the chain extender is 75%.

[0056] S5. After the reaction is completed, the mixture is poured into a polytetrafluoroethylene (PTFE) mold and dried in an oven at 80°C for 2 days to obtain the final self-healing polymer, named PPG-A-75% SS.

[0057] S6. Use a fused deposition model heated extrusion 3D printer and set the printing parameters. Set the printing temperature to 130°C and the platform cooling temperature to room temperature (25°C). Select an extrusion nozzle diameter of 1mm. Set the layer height to 1mm and the default extrusion width to 1mm. Set the fill density to 100% and the nozzle speed to 3mm / s. -1 , the layer height is limited to 1mm.

[0058] S7. After the self-repairing material flows out of the nozzle stably, select the print file and start printing.

[0059] After printing is complete, wait for the sample to cool for 3 minutes before removing it from the oven. Place the sample in a 60°C oven for defect repair. After 24 hours, the internal defects and interlayer gaps caused by FDM fused deposition modeling are completely repaired.

[0060] Example 2

[0061] The preparation steps are the same as those in Example 1;

[0062] The difference is that in step S4, 0.348 g of adipic acid dihydrazide was weighed and dissolved in DMF by heating. 0.4967 g of 2,2-diaminodiphenyl disulfide was weighed and dissolved in DMF and slowly added dropwise to the reaction solution in S2. The chain extension reaction was carried out at 60°C for 24 hours. The molar proportion of DTDA in the chain extender was 50%.

[0063] Finally, the self-healing polymer was obtained and named PPG-A-50%SS.

[0064] Example 3

[0065] The preparation steps are the same as those in Example 1;

[0066] The difference is that in step S4, 0.522 g of adipic acid dihydrazide was weighed and dissolved in DMF by heating. 0.2484 g of 2,2-diaminodiphenyl disulfide was weighed and dissolved in DMF and slowly added dropwise to the reaction solution in S2. The chain extension reaction was carried out at 60°C for 24 h. The molar proportion of DTDA in the chain extender was 25%.

[0067] Finally, the self-healing polymer was obtained and named PPG-A-25%SS.

[0068] Example 4

[0069] The preparation steps are the same as those in Example 1;

[0070] The difference is that in step S4, 0.696 g of adipic acid dihydrazide was weighed, heated and dissolved in DMF, and slowly added dropwise to the reaction solution in S2, and the chain extension reaction was carried out at 60°C for 24 hours. The chain extender contained only adipic acid dihydrazide, and the molar proportion of DTDA in the chain extender was 0%.

[0071] The final polymer was named PPG-A.

[0072] Example 5

[0073] The preparation steps are the same as those in Example 1;

[0074] The difference is that in step S4, 0.9934 g of 2,2-diaminodiphenyl disulfide was weighed and dissolved in DMF, which was slowly added dropwise to the reaction solution in S2, and the chain extension reaction was carried out at 60°C for 24 hours. The chain extender contained only 2,2-diaminodiphenyl disulfide, and the molar proportion of DTDA in the chain extender was 100%.

[0075] The final polymer was named PPG-SS.

[0076] Experimental results:

[0077] The PPG-A-75%SS, PPG-A-50%SS, PPG-A-25%SS, PPG-A, and PPG-SS polymers prepared in Examples 1 to 5 were subjected to infrared scanning, and the results are shown in the attached figure. Figure 1 As shown. Figure 1 It can be seen that the presence of characteristic peaks such as the stretching vibration peak of the internal NH group and the symmetric and antisymmetric stretching vibration peaks of CH confirms the successful synthesis of the self-healing polymer.

[0078] The polymers obtained in Examples 1 to 5 were scanned with nuclear magnetic resonance (NMR), and the results are shown in the attached figure. Figure 2 As shown. Figure 2 The characteristic peaks on the curve correspond to the chemical structures. The characteristic peaks of aromatic hydrogen and 2-aminothiophenol are similar, confirming the successful introduction of the disulfide. The four peaks appearing at 6-7 ppm clearly indicate the presence of 2'2-diaminodiphenyl disulfide structures, which are absent from the PPG-A prepared in Example 4.

[0079] The self-repairing polymers prepared in Examples 1 to 5 above were scanned by Raman spectroscopy, and the results are shown in the attached figure. Figure 3 As shown. Figure 3It can be seen that at 486 cm-1, the characteristic vibration peaks of SS bonds are clearly visible in PPG-A-25% SS, PPG-A-50% SS, PPG-A-75% SS, and PPG-SS. PPG-A is different because it does not contain DTDA.

[0080] The polymers obtained in Examples 1 to 5 were scanned by XRD, and the results are shown in the attached figure. Figure 4 As shown. Figure 4 It can be seen that there are two broad and short peaks in the XRD curve, indicating that the polymers prepared in Examples 1 to 5 are all amorphous.

[0081] The polymers obtained in Examples 1 to 5 were subjected to TGA thermal stability tests, and the results are shown in the attached figure. Figure 5 As shown. Figure 5 It can be seen that the polymers prepared in Examples 1 to 5 all have initial decomposition temperatures above 200° C. and have excellent thermal stability.

[0082] The polymers obtained in Examples 1 to 5 were subjected to AFM tests, and the results are shown in the attached figure. Figure 6 As shown. Figure 6 It can be seen that the microphase separation results of the samples prepared in the five examples are obvious, the ADH content gradually decreases, and the degree of polymer microphase separation gradually weakens.

[0083] The polymers obtained in Examples 1 to 5 were subjected to tensile test, and the results are shown in the attached figure. Figure 7 As shown. Figure 7 It can be seen that PPG-A has the highest maximum tensile strength, reaching 27.2MPa, and the elongation at break is 1811%. The tensile strength of PPG-A-25%SS is 17.3MPa, and the elongation at break is 2109%. The tensile strength of PPG-A-50%SS is 6.25MPa, and the elongation at break is 2162%. The tensile strength of PPG-A-75%SS is 4.05MPa, and the elongation at break is 2445%. The tensile strength of PPG-SS is 0.14MPa, and the elongation at break is 4950%. From the comparison of tensile strength, the mechanical properties of PPG-SS are too poor.

[0084] The self-repairing performance of the polymers prepared in Examples 1 to 5 above was tested, and the results are shown in the attached figure. Figures 8-9 shown. Figure 8 a is a comparison chart of PPG-SS repair tensile test at 60℃, Figure 8 b is the comparison chart of tensile test of PPG-A-75% SS at 60℃, Figure 8 c is the comparison chart of PPG-A-50% SS repair tensile test at 60℃, Figure 9 a is a comparison chart of the repair tensile test of PPG-A-25% SS at 100°C. Figure 9 Figure b compares the repair tensile test results of PPG-A at 100°C. After 10 minutes at 60°C, PPG-SS achieved a tensile strength of 92.8% of its original value, and its elongation at break recovered to 85%, demonstrating excellent self-repair rate and efficiency. The maximum tensile strength and elongation at break of PPG-A-75% SS recovered to 95.8% and 95.4%, respectively. PPG-A-50% SS, PPG-A-25% SS, and PPG-A showed virtually no self-repair capability.

[0085] The polymers prepared in Examples 1 and 5 were subjected to a microscope scratch self-repair test, and the results are shown in the attached figure. Figure 10 、 11 As shown. Figure 10 、 11 It can be seen that the scratches on PPG-SS and PPG-A-75%SS almost completely disappear at 60 °C, indicating excellent self-healing ability.

[0086] The rheological properties of the PPG-A-75% SS polymer prepared in Example 1 were tested, and the results are shown in the attached figure. Figure 12 As shown. Figure 12 It can be seen that the viscosity of PPG-A-75% SS gradually decreases with increasing temperature. When the temperature is above 107°C, its viscosity is less than 1000 Pa.s. At a temperature of 120°C, its viscosity is 340 Pa.s. Therefore, at 130°C, PPG-A-75% SS polymer can be smoothly extruded from the 3D printer nozzle.

[0087] The PPG-A-75% SS polymer prepared in Example 1 was printed and extruded. The actual extrusion diagram is shown in FIG. Figure 13 As shown. Figure 13 It can be seen that PPG-A-75% SS is used as the printing material, and the extruded filament is smooth and has no defects.

[0088] The double-layer square sheet printed with the PPG-A-75% SS polymer prepared in Example 1 was repaired and photographed with a microscope. The results are shown in the attached figure. Figure 14 As shown. Figure 14 It can be seen that the gap at circle 1 is the gap between the first layer, 2 is the gap between the second layer, and there is a large printing defect at position 3. After leaving it in a 60°C environment for 12 hours, both the interlayer gaps and internal defects have become significantly smaller. After 24 hours of repair, the interlayer gaps of the first layer are almost completely healed, and the interlayer gaps of the second layer have not healed but have been greatly reduced. When the repair time reaches 36 hours, the interlayer gaps of the first layer completely disappear, and after 72 hours, the interlayer gaps of the second layer also disappear. The relatively large defects in printing can also completely disappear after 12 days.

[0089] The above describes in detail the preferred embodiment 1 of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solution that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A polymer capable of self-repairing interlayer defects in FDM printing, characterized in that: It has the following structure: Wherein, m and n are the number of repeating units, m ranges from 6 to 40, and n ranges from 30 to 40.

2. A method for preparing a self-repairing polymer, characterized in that: The following steps are involved: (1) subjecting polypropylene glycol to a vacuum treatment at 85-150°C for 1-3 hours to eliminate air and moisture inside, and then filling with nitrogen for protection; (2) After lowering the temperature to 70-85°C, the DMF solution of isophorone diisocyanate is added dropwise to the treated polypropylene glycol, and then a small amount of dibutyltin dilaurate is added dropwise. After the addition is completed, the prepolymerization reaction is stirred for a period of time. During the reaction, the molar ratio of polypropylene glycol to isophorone diisocyanate is controlled to be 1:3; (3) lowering the temperature to 40-70° C. again, adding the DMF solution of the chain extender to the system of step (2), stirring the chain extension reaction for a period of time after the addition is completed, and obtaining the target product after drying, wherein the chain extender is adipic acid dihydrazide and 2,2-diaminodiphenyl disulfide.

3. The method according to claim 2, wherein The mass of dibutyltin dilaurate is 0.1-0.2g.

4. The method according to claim 2, wherein The prepolymerization reaction was stirred for more than 3 hours after the addition was completed.

5. The method according to claim 2, wherein After the addition was completed, the chain extension reaction was stirred for more than 16 hours.

6. The method according to claim 2, wherein The molar ratio of the total molar amount of the chain extender to the polypropylene glycol is 2:1, and the molar proportion of 2,2-diaminodiphenyl disulfide in the chain extender is greater than 50%, preferably 60-90%.

7. The method according to claim 2, wherein After the dropwise addition is completed, the chain extension reaction is stirred for a period of time, and the target product is obtained after drying. The drying temperature is 40-80° C. and the drying time is 1-2 days.

8. Use of the self-healing polymer according to claim 1 as a fused deposition type 3D printing material.

9. The use according to claim 8, characterized in that Use a fused deposition model heated extrusion 3D printer, set the printing parameters, set the printing temperature to 90-140°C, the platform cooling temperature to room temperature 25°C; select an extrusion nozzle diameter of 0.4-2mm; set the layer height to 0.1-1mm, the default extrusion width to 0.1-1mm; the filling density is 100%, set the nozzle speed, and limit the layer height to 0.1-2mm.

10. The use according to claim 8, characterized in that After printing is completed, wait for the sample to cool down for 1 to 3 minutes, and then place the sample in an oven at 60 to 80°C for 1 to 2 days to repair the defects.

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