High-toughness high-layer cohesive polyester for 3D printing and preparation method thereof

Abstract

The application relates to the field of 3D printing, and particularly discloses a high-toughness high-layer cohesive polyester for 3D printing and a preparation method thereof. According to 100% by mass percentage, the raw materials of the polyester contain 0.2-3% of an antioxidant, 0.1-3% of a dispersing agent, and the balance of a base resin; the base resin contains the following raw materials: a dibasic acid, a dihydric alcohol, a grafting polymer, a catalyst and a protective agent. The polyester introduces the grafting polymer containing active groups such as hydroxyl groups into the base resin, improves the melt uniformity of the whole blending system, reduces the interfacial energy, makes the polyester molecular chain more easily cross the interlayer interface to move and entangle, forms stronger physical connection, makes the layers more easily bonded and not cracked during 3D printing, has excellent interlayer adhesion, meets the application requirements of the high-value-added industrial 3D printing field, and can be applied to the fields of outdoor handicrafts, the building industry, the aerospace field and medical devices.

Description

Technical Field

[0001] This invention belongs to the field of 3D printing, specifically relating to a high-toughness high-layer viscose polyester for 3D printing and its preparation method. Background Technology

[0002] Fused Deposition Modeling (FDM) technology, one of the most widely used technologies in the current 3D printing field, operates on the core principle of heating a thermoplastic filament to a temperature slightly above its melting point. This filament is then extruded through a nozzle and deposited layer by layer to create a three-dimensional solid. In the FDM process, the filament is fed into the nozzle via a feeding mechanism. After being heated and melted within the nozzle, it is extruded through a nozzle equipped with micro-nozzles. The molten material cools and solidifies rapidly after extrusion, bonding with the previous layer. Once one layer is deposited, the stage descends by one layer thickness, and the next layer is deposited, continuing until the entire solid model is complete.

[0003] Since its successful development by American scholar Dr. Scott Crump in 1988, FDM technology has been widely used in various industries such as home DIY, education and training, and cultural and creative industries due to its advantages such as simple operation, low equipment threshold, and relatively low manufacturing cost. Although FDM has many advantages, some problems still exist. For example, patent CN112063130B discloses a 3D printing copolyester and its preparation method. By blending PBAT, aliphatic polyester, modified carbon materials, aromatic-aliphatic-aromatic block copolymers, and acrylates, the toughness of the copolyester filament is improved, solving the problem of filament breakage under the traction force of the drive wheel during printing. Another example is patent CN111087780BD, which modifies polycarbonate / aliphatic aromatic copolyester, allowing for lower nozzle and substrate temperatures during the printing process, solving problems such as excessively high PC printing temperatures and severe warping.

[0004] While the aforementioned patents have addressed some issues, the bonding between layers in FDM products primarily relies on polymer molecule diffusion and the re-entanglement and interweaving of adjacent layer interfaces. However, the extrusion and deposition of each filament layer during printing occur under relatively independent conditions and are influenced by factors such as layer thickness, crystallization rate, and printing speed. This leads to insufficient fusion of the filaments between layers during printing, resulting in inadequate interlayer bonding strength. Currently, with the continuous expansion of 3D printing technology in high-value-added fields such as aerospace, automotive parts, and medical equipment, polyester materials require excellent mechanical properties, good flowability, and high interlayer adhesion to meet the manufacturing needs of complex structural parts and functional components. Therefore, there is an urgent need in the market for a polyester material with high interlayer adhesion for 3D printing. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, this invention provides a high-toughness, high-layer adhesive polyester for 3D printing, meeting the high-value-added application requirements of industrial 3D printing. This polyester has excellent interlayer adhesion and can be used in outdoor crafts, construction, aerospace, medical devices, and other fields. By introducing graft polymers containing active groups such as hydroxyl groups into the matrix resin, the melt uniformity of the entire blend system is improved, the interfacial energy is reduced, and the polyester molecular chains can more easily move and entangle across the interlayer interfaces, forming a stronger physical connection. This makes it easier for the layers to bond and prevent cracking during 3D printing.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] This invention provides a high-toughness, high-layer viscose polyester for 3D printing, comprising, by weight percentage, 0.2-3% antioxidant, 0.1-3% dispersant, and the balance being a matrix resin; the preparation steps of the matrix resin are as follows:

[0008] Dicarboxylic acid, diol, graft polymer, catalyst, and protective agent are added to a reactor. Under nitrogen protection, the reaction temperature is controlled at 220-240℃ and the pressure inside the reactor is 0.1-0.3MPa. The esterification reaction is carried out for 2-5 hours. Then, the catalyst is added, the temperature is raised to 260-290℃, the pressure is reduced to 50-100Pa, and the polycondensation reaction is carried out for 2-5 hours. After the reaction is completed, the matrix resin is obtained by discharging the material.

[0009] This invention introduces graft polymers containing active groups such as hydroxyl groups into a matrix resin. Through joint participation in the polymerization reaction, a "rigid-flexible" dual spatial network structure is formed. The rigid part can provide the necessary strength and stability to ensure that the material is not easily deformed or damaged when subjected to load. The flexible part, on the other hand, gives the material a certain degree of ductility and toughness, enabling it to absorb impact energy without breaking.

[0010] In some embodiments, the molar ratio of the dicarboxylic acid to the diol is 1:(1.1-1.5).

[0011] In some embodiments, the dicarboxylic acid is at least one of aromatic dicarboxylic acids.

[0012] In some embodiments, the diol is at least one of aliphatic chain diols and aliphatic cyclic diols.

[0013] Preferably, the diol comprises ethylene glycol, neopentyl glycol, and polytetrahydrofuran ether diol.

[0014] This invention adapts diacids and diols to 3D printing processes through specific selection. Firstly, the neopentyl structure at the β-carbon position of neopentyl glycol (containing two methyl groups) disrupts the regular stacking of the molecular chain, reducing the crystallization rate and crystallinity. This crystallization inhibition lowers melt viscosity, ensuring smooth extrusion and reducing the risk of nozzle clogging. Secondly, the steric hindrance of the side groups in neopentyl glycol reduces molecular chain orientation, decreasing the cooling shrinkage rate of the printed part and thus alleviating warping. Thirdly, the polar groups of ethylene glycol and neopentyl glycol synergistically increase molecular chain polarity, promoting interlayer molecular diffusion and enhancing interlayer shear strength. Fourthly, the introduction of polytetrahydrofuran ether glycol replaces some short-chain diols, enhancing molecular chain flexibility and fatigue resistance.

[0015] In some embodiments, the graft polymer accounts for 0.5-5% of the total mass of the diacid and diol.

[0016] In some embodiments, the protective agent is at least one selected from p-methoxyphenol, triphenyl phosphite, ammonium dihydrogen phosphate, and bisphenol A phosphite.

[0017] In some embodiments, the preparation steps of the grafted polymer are as follows:

[0018] S1. Under nitrogen protection, maleic anhydride, itaconic anhydride and polyurethane are added to tetrahydrofuran, then a catalyst is added, and the mixture is stirred at 70-110℃ for 2-4 hours. After stirring, the tetrahydrofuran is removed and the mixture is dried under vacuum to obtain grafted polyurethane.

[0019] S2. Add tetraethyl silicate and catalyst to purified water and stir at room temperature for 0.5-1 h to obtain hydrolyzed tetraethyl silicate;

[0020] S3. Hydrolyzed tetraethyl silicate, grafted polyurethane and catalyst are stirred in anhydrous ethanol at room temperature for 1-3 hours to obtain the grafted polymer.

[0021] This invention utilizes grafted polymers to promote the diffusion and entanglement of macromolecular chains, improving the melt homogeneity of the entire blend system, reducing interfacial energy, and making it easier for polyester molecular chains to move and entangle across interlayer interfaces, forming stronger physical bonds. Simultaneously, the addition of grafted polymers optimizes the melt flow index, achieving an ideal state that ensures smooth extrusion while promoting full interlayer fusion, making it more suitable for 3D printing. Furthermore, TEOS hydrolyzes to contain a large number of hydroxyl active groups, increasing the surface energy of the polyester and making it easier for hydroxyl groups to form hydrogen bonds and other chemical bonds, resulting in easier interlayer adhesion and less cracking during 3D printing.

[0022] In some embodiments, the polyurethane contains a biphenyl hydroquinone structure.

[0023] This invention specifically employs polyurethane containing biphenyl segments, which triggers shape recovery at temperatures close to the interlayer temperature of 3D printing, thereby enhancing the rearrangement of interlayer molecular chains.

[0024] In some embodiments, the molar ratio of maleic anhydride to itaconic anhydride is 1:(0.3-0.5).

[0025] This invention employs maleic anhydride and itaconic anhydride in synergy, wherein itaconic anhydride can increase crosslinking sites to enhance interlayer adhesion strength.

[0026] In some embodiments, the dispersant is polyethylene oxide and cationic polyacrylamide.

[0027] In some embodiments, the mass ratio of the polyethylene oxide to the cationic polyacrylamide is 1:(0.1-0.2).

[0028] Another aspect of the present invention provides a method for preparing the above-mentioned high-toughness high-layer viscose polyester, the specific steps of which are as follows: the matrix resin, antioxidant and dispersant are melt-blended and discharged into filaments to obtain the high-toughness high-layer viscose polyester.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. This invention provides a polyester for 3D printing, which exhibits excellent interlayer adhesion and can be used in outdoor crafts, construction, aerospace, medical devices, and other fields. By introducing a graft polymer containing active groups such as hydroxyl groups into the matrix resin, it participates in the polymerization reaction with the raw materials to form a "rigid-flexible" dual-dimensional spatial network structure. The rigid portion provides the necessary strength and stability, ensuring that the material is not easily deformed or damaged under load; while the flexible portion imparts a certain degree of ductility and toughness to the material, enabling it to absorb impact energy without breaking.

[0031] 2. This invention adapts diacids and diols to the 3D printing process through specific selection. The use of neopentyl glycol reduces melt viscosity, ensuring smooth extrusion and minimizing nozzle clogging risk. Furthermore, its side group steric hindrance reduces molecular chain orientation, lowering the cooling shrinkage rate of the printed part and alleviating warping. Simultaneously, the polar groups of ethylene glycol and neopentyl glycol synergistically increase molecular chain polarity, promoting interlayer molecular diffusion and enhancing interlayer shear strength. In addition, the introduction of polytetrahydrofuran ether diol replaces some short-chain diols, enhancing molecular chain flexibility and fatigue resistance.

[0032] 3. This invention utilizes grafted polymers to promote the diffusion and entanglement of macromolecular chains, improving the melt uniformity of the entire blend system, reducing interfacial energy, and making it easier for polyester molecular chains to move and entangle across interlayer interfaces, forming stronger physical bonds. Simultaneously, the addition of grafted polymers optimizes the melt flow index, achieving an ideal state that ensures smooth extrusion while promoting full interlayer fusion, making it more suitable for 3D printing. In the preparation of the grafted polymers, maleic anhydride and itaconic anhydride are used synergistically. The dicarboxyl structure of itaconic anhydride increases crosslinking sites to enhance interlayer adhesion strength; furthermore, TEOS hydrolysis contains a large number of hydroxyl active groups, increasing the surface energy of PETG polyester, and the hydroxyl groups more easily form hydrogen bonds and other chemical bonds, making it easier for the layers to bond and preventing cracking during 3D printing.

[0033] 4. This invention specifically uses polyurethane containing biphenyl segments, which triggers shape recovery when the material is close to the interlayer temperature of 3D printing, thereby enhancing the rearrangement of interlayer molecular chains. Detailed Implementation

[0034] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0035] It is worth noting that, unless otherwise specified, the raw materials used in the following preparation examples and embodiments are all from any commercially available manufacturer:

[0036] The polyethylene oxide model is PEO-18; the cationic polyacrylamide model is Accopearl R-150.

[0037] Preparation Example 1

[0038] The preparation steps of grafted polymer A are as follows:

[0039] S1. Under nitrogen protection, 0.1 mol maleic anhydride, 0.04 mol itaconic anhydride, and 0.1 mol polyurethane BP-PU-1000 (customized) were added to 100 mL tetrahydrofuran, and then 15 mL triethylamine was added. The mixture was stirred at 80 °C for 3 h. After stirring, the tetrahydrofuran was removed and the mixture was dried under vacuum to obtain the grafted polyurethane.

[0040] S2. Add 10g of tetraethyl silicate and 10ml of citric acid to 2g of purified water and stir at room temperature for 0.5h to obtain hydrolyzed tetraethyl silicate.

[0041] S3. 100g of hydrolyzed tetraethyl silicate, 1g of grafted polyurethane and 0.1ml of citric acid are stirred in 2ml of anhydrous ethanol at room temperature for 2h to obtain grafted polymer A.

[0042] Preparation Example 2

[0043] The preparation steps of grafted polymer B differ from those in Preparation Example 1 in that, in S1, itaconic anhydride is replaced by an equal amount of maleic anhydride.

[0044] Preparation Example 3

[0045] The preparation steps of grafted polymer C are as follows:

[0046] Under nitrogen protection, 0.1 mol maleic anhydride, 0.04 mol itaconic anhydride, and 0.1 mol polyurethane BP-PU-1000 (customized) were added to 100 mL tetrahydrofuran, followed by the addition of 15 mL triethylamine. The mixture was stirred at 80 °C for 3 h. After stirring, the tetrahydrofuran was removed and the mixture was dried under vacuum to obtain graft polymer C.

[0047] Preparation Example 4

[0048] The preparation steps of matrix resin A are as follows:

[0049] 1 mol of terephthalic acid, 0.8 mol of ethylene glycol, 0.3 mol of neopentyl glycol, 0.2 mol of polytetrahydrofuran ether glycol PTMEG-650, 5 wt% of graft polymer A, 0.2 wt% of tetrabutyl titanate, and 0.1 wt% of triphenyl phosphite were added to a reactor. Under nitrogen protection, the reaction temperature was controlled at 230℃ and the pressure inside the reactor was 0.2 MPa. The esterification reaction was carried out for 4 hours. Then, 0.1 wt% of tetrabutyl titanate was added, the temperature was raised to 270℃, the pressure was reduced to 70 Pa, and the polycondensation reaction was carried out for 3 hours. After the reaction was completed, the matrix resin A was discharged.

[0050] Preparation Example 5

[0051] The difference between the preparation steps of matrix resin B and those in preparation example 4 is that the diol used is 0.9 mol ethylene glycol and 0.4 mol neopentyl glycol.

[0052] Preparation Example 6

[0053] The preparation steps of matrix resin C differ from those in Preparation Example 4 in that the diol used is 1.0 mol ethylene glycol and 0.3 mol polytetrahydrofuran ether diol PTMEG-650.

[0054] Preparation Example 7

[0055] The preparation steps of the matrix resin D differ from those in Preparation Example 4 in that the graft polymer A is replaced by an equal amount of graft polymer B.

[0056] Preparation Example 8

[0057] The preparation steps of the matrix resin E differ from those in Preparation Example 4 in that the graft polymer A is replaced by an equal amount of graft polymer C.

[0058] Preparation Example 9

[0059] The preparation steps of matrix resin F are as follows:

[0060] 1 mol of terephthalic acid, 0.8 mol of ethylene glycol, 0.3 mol of neopentyl glycol, 0.2 mol of polytetrahydrofuran ether glycol PTMEG-650, 0.2 wt% of tetrabutyl titanate, and 0.1 wt% of triphenyl phosphite were added to a reactor. Under nitrogen protection, the reaction temperature was controlled at 230℃ and the pressure inside the reactor was 0.2 MPa. The esterification reaction was carried out for 4 hours. Then, 0.1 wt% of tetrabutyl titanate was added, the temperature was raised to 270℃, the pressure was reduced to 70 Pa, and the polycondensation reaction was carried out for 3 hours. After the reaction was completed, the matrix resin F was discharged.

[0061] Example 1

[0062] A high-toughness high-layer viscose polyester for 3D printing, comprising, by weight percentage, 2% antioxidant 1010, 1.15% dispersant (1% polyethylene oxide, 0.15% cationic polyacrylamide), and the balance being matrix resin A.

[0063] The preparation method of high-toughness high-layer viscose polyester for 3D printing in this embodiment specifically includes the following steps:

[0064] The matrix resin A, antioxidant 1010, and dispersant are melt-blended and discharged into filaments to obtain high-toughness high-layer viscose polyester.

[0065] Example 2

[0066] A high-toughness high-layer viscose polyester for 3D printing, comprising, by weight percentage, 0.2% antioxidant 1010, 0.1% dispersant (0.09% polyethylene oxide, 0.01% cationic polyacrylamide), and the balance being matrix resin A.

[0067] The preparation method of the high-toughness high-layer viscose polyester for 3D printing in this embodiment is the same as that in Embodiment 1.

[0068] Example 3

[0069] A high-toughness high-layer viscose polyester for 3D printing, comprising, by weight percentage, 3% antioxidant 1010, 3% dispersant (2.5% polyethylene oxide, 0.5% cationic polyacrylamide), and the balance being matrix resin A.

[0070] The preparation method of the high-toughness high-layer viscose polyester for 3D printing in this embodiment is the same as that in Embodiment 1.

[0071] Example 4

[0072] This embodiment provides a high-toughness high-layer viscose polyester for 3D printing and its preparation method. The specific implementation method is the same as that in Embodiment 1, except that the matrix resin A is replaced by an equal amount of matrix resin B.

[0073] Example 5

[0074] This embodiment provides a high-toughness high-layer viscose polyester for 3D printing and its preparation method. The specific implementation method is the same as that in Embodiment 1, except that the matrix resin A is replaced by an equal amount of matrix resin C.

[0075] Example 6

[0076] This embodiment provides a high-toughness high-layer viscose polyester for 3D printing and its preparation method. The specific implementation method is the same as that in Embodiment 1, except that the matrix resin A is replaced by an equal amount of matrix resin D.

[0077] Example 7

[0078] This embodiment provides a high-toughness high-layer viscose polyester for 3D printing and its preparation method. The specific implementation method is the same as that in Embodiment 1, except that the matrix resin A is replaced by an equal amount of matrix resin E.

[0079] Comparative Example 1

[0080] This comparative example provides a high-toughness high-layer viscose polyester for 3D printing and its preparation method. The specific implementation method is the same as in Example 1, except that the matrix resin A is replaced by an equal amount of matrix resin F.

[0081] Performance testing:

[0082] The polyesters obtained in Examples 1-7 and Comparative Example 1 were used to form 3D printed objects by fused deposition modeling. For details on the preparation of 3D printed samples, please refer to "Preparation and Shape Memory Performance Study of PLA_PBSA_Carbon Black Based on Fused Deposition Modeling 3D Printing - Song Junyu 2.2.5". The obtained samples were subjected to the following performance tests, and the results are shown in Table 1.

[0083] Table 1

[0084]

[0085] In Table 1, the matrix resins of Examples 1-3 all used terephthalic acid as the dicarboxylic acid and ethylene glycol, neopentyl glycol and polytetrahydrofuran ether glycol as diols. They also used the same grafted polymers and exhibited similar and good tensile strength, notched impact strength and shrinkage.

[0086] Compared to Example 1, Example 4 removed polytetrahydrofuran ether glycol from the diol, which reduced the flexibility of the molecular chain and resulted in a slight decrease in tensile strength, but the notched impact strength and shrinkage rate did not change much; Example 5 removed neopentyl glycol from the diol, which was not conducive to reducing molecular chain orientation and resulted in an increase in the shrinkage rate of the printed parts.

[0087] Compared to Example 1, the grafted polymer used in Example 6 completely replaced the mixture of maleic anhydride and itaconic anhydride with maleic anhydride in the matrix resin. This reduced the number of crosslinking sites, leading to a decrease in interlayer adhesion strength, manifested as a decrease in notched impact strength. The grafted polymer used in Example 7 removed hydrolyzed tetraethyl silicate, also resulting in a decrease in notched impact strength. This may be because hydrolyzed TEOS contains a large number of active hydroxyl groups, increasing the surface energy of the polyester and making it easier for hydroxyl groups to form hydrogen bonds and other chemical bonds, resulting in easier adhesion and less cracking between layers during 3D printing. Compared to Example 1, the matrix resin in Comparative Example 1 did not contain a grafted polymer, only reacting with a diacid and a diol. This is not conducive to the movement and entanglement of the resulting polyester molecular chains across the interlayer interfaces, leading to a decrease in notched impact strength and tensile strength.

[0088] The embodiments and comparative examples described above do not limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A high-toughness, high-layer viscose polyester for 3D printing, characterized in that, The raw materials, by weight percentage (100%), contain 0.2-3% antioxidant, 0.1-3% dispersant, and the balance is matrix resin; the preparation steps of the matrix resin are as follows: Dicarboxylic acid, diol, graft polymer, catalyst, and protective agent are added to a reactor. Under nitrogen protection, the reaction temperature is controlled at 220-240℃ and the pressure inside the reactor is 0.1-0.3MPa. The esterification reaction is carried out for 2-5 hours. Then, the catalyst is added, the temperature is raised to 260-290℃, the pressure is reduced to 50-100Pa, and the polycondensation reaction is carried out for 2-5 hours. After the reaction is completed, the matrix resin is obtained by discharging the material. The preparation steps of the grafted polymer are as follows: S1. Under nitrogen protection, maleic anhydride, itaconic anhydride and polyurethane are added to tetrahydrofuran, then a catalyst is added, and the mixture is stirred at 70-110℃ for 2-4 hours. After stirring, the tetrahydrofuran is removed and the mixture is dried under vacuum to obtain grafted polyurethane. S2. Add tetraethyl silicate and catalyst to purified water and stir at room temperature for 0.5-1 h to obtain hydrolyzed tetraethyl silicate; S3. Hydrolyzed tetraethyl silicate, grafted polyurethane and catalyst are stirred in anhydrous ethanol at room temperature for 1-3 hours to obtain the grafted polymer. The polyurethane contains a biphenyl hydroquinone structure.

2. The high-toughness high-layer viscose polyester for 3D printing according to claim 1, characterized in that, The molar ratio of the dicarboxylic acid to the diol is 1:(1.1-1.5).

3. The high-toughness high-layer viscose polyester for 3D printing according to claim 1, characterized in that, The dicarboxylic acid is an aromatic dicarboxylic acid.

4. The high-toughness high-layer viscose polyester for 3D printing according to claim 1, characterized in that, The diol is at least one of aliphatic chain diols and aliphatic cyclic diols.

5. The high-toughness high-layer viscose polyester for 3D printing according to claim 1, characterized in that, The grafted polymer accounts for 0.5-5% of the total mass of the dicarboxylic acid and diol.

6. The high-toughness high-layer viscose polyester for 3D printing according to claim 1, characterized in that, The protective agent is at least one of p-methoxyphenol, triphenyl phosphite, ammonium dihydrogen phosphate, and bisphenol A phosphite.

7. The high-toughness high-layer viscose polyester for 3D printing according to claim 1, characterized in that, The molar ratio of maleic anhydride to itaconic anhydride is 1:(0.3-0.5).

8. The high-toughness high-layer viscose polyester for 3D printing according to claim 1, characterized in that, The dispersant is polyethylene oxide and cationic polyacrylamide.

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