TPU wire rod for 3D printing and preparation method thereof

Abstract

The invention relates to the technical field of 3D printing materials, and particularly provides a TPU wire rod for 3D printing and a preparation method thereof.The TPU wire rod comprises polyester type thermoplastic polyurethane and a modified polyester component, the modified polyester component is prepared from hydroxy acid and / or dicarboxylic acid and a dihydroxy compound through a condensation polymerization reaction, and the modified polyester component is prepared from polyester type thermoplastic polyurethane; at least part of the tail end of a molecular chain of the modified polyester component has carbon-carbon unsaturated bonds, the modified polyester component is modified by fatty acid or fatty acid derivatives, the molecular structure of the modified polyester component is designed, the modified polyester component is introduced into a polyester type thermoplastic polyurethane system, and the continuous filament-shaped TPU wire is prepared through melt blending and extrusion molding. A new technical scheme can be provided for the material structure design of the TPU wire rod, and the TPU wire rod is suitable for melt extrusion type 3D printing application.

Description

Technical Field

[0001] This invention belongs to the technical field of 3D printing filaments, and more specifically, relates to a TPU filament for 3D printing and its preparation method. Background Technology

[0002] With the development of additive manufacturing technology, fused deposition modeling (FDM) 3D printing has been widely used in industrial manufacturing, product prototyping, and the fabrication of functional structural components due to its simple equipment structure and wide material adaptability. The filaments used in FDM 3D printing typically need to possess good continuous extrusion performance, stable feeding characteristics, and a material structure that can adapt to the thermal cycling of the printing process.

[0003] Thermoplastic polyurethane (TPU) is increasingly being used in the field of 3D printing filaments due to its excellent flexibility, abrasion resistance, and processing performance. Existing TPU filaments mostly employ a single polymer system or adjust material properties through simple blending, resulting in relatively limited formulation design dimensions. There is still room for improvement in the flexibility of material structure control under different printing conditions or application scenarios.

[0004] On the other hand, polyester materials have certain advantages in terms of material performance control due to their strong designability of molecular structure. However, when polyester materials are directly applied to TPU filament systems, problems such as compatibility and processing stability are easily encountered.

[0005] Therefore, how to introduce structurally controllable polyester components to expand the material design space of TPU filaments while maintaining their processing characteristics is one of the technical issues that those skilled in the art need to consider. Summary of the Invention

[0006] This invention aims to provide a TPU filament for 3D printing. By introducing a modified polyester component with a specific structure into a polyester-type thermoplastic polyurethane system, the structure of the filament material can be adjusted, thereby providing a new technical solution for the formulation design of TPU filaments.

[0007] The purpose and effectiveness of this invention—a TPU filament for 3D printing and its preparation method—are achieved through the following specific technical means: A TPU filament for 3D printing comprises the following components in parts by weight: 70-95 parts of polyester-based thermoplastic polyurethane; The modified polyester component comprises 8 to 30 parts, wherein the modified polyester component is prepared by polycondensation reaction of hydroxy acid and / or dicarboxylic acid with dihydroxy compound, and the number average molecular weight of the modified polyester component is 1,000 to 8,000 g / mol. The modified polyester component has at least a portion of carbon-carbon unsaturated bonds at the ends of its molecular chains, and the molar fraction of the carbon-carbon unsaturated end groups at the ends of the modified polyester molecular chains is 0.5 mol% to 10 mol%. Furthermore, the modified polyester component is modified with fatty acids or fatty acid derivatives.

[0008] Furthermore, the hydroxy acid is selected from one or more of lactic acid, glycolic acid, hydroxybutyric acid, and hydroxyvalerate.

[0009] Furthermore, the dicarboxylic acid is selected from one or more of terephthalic acid, adipic acid, and succinic acid, and the dihydroxy compound is selected from one or more of ethylene glycol, 1,4-butanediol, and 1,6-hexanediol.

[0010] Furthermore, the carbon-carbon unsaturated bonds are derived from maleic acid, fumaric acid, itaconic acid, or their derivatives.

[0011] Furthermore, the fatty acid is selected from one or more of stearic acid, oleic acid, linoleic acid, ricinoleic acid, or rosin acid.

[0012] Furthermore, the fatty acids are grafted or block-linked onto the molecular chain of the modified polyester component via ester bonds.

[0013] Furthermore, the polyester-type thermoplastic polyurethane is prepared by reacting polyester polyol, diisocyanate and chain extender.

[0014] Furthermore, the wire is a continuous filament material prepared by melt extrusion.

[0015] The present invention provides a method for preparing TPU wire as described above, comprising the following steps: weighing polyester thermoplastic polyurethane and modified polyester components according to the stated weight parts, melt-blending and extruding to obtain TPU wire.

[0016] In the technical solution of the present invention, the modified polyester component is not used as a conventional filler or a simple modifying agent, but rather its molecular structure is designed in a targeted manner so that it plays a structural regulation role in the polyester-type thermoplastic polyurethane system.

[0017] Specifically, by controlling the molecular weight of the modified polyester component to be in a low range, it has good fluidity and dispersibility in the molten state, which facilitates uniform blending in the TPU matrix. At the same time, a controlled proportion of carbon-carbon unsaturated structures are introduced at the ends of the modified polyester molecular chains, which gives the ends of the molecular chains a certain degree of structural activity, which is beneficial for forming stable physical or chemical interactions with the TPU molecular chains during melt processing.

[0018] Furthermore, by modifying the modified polyester component with fatty acids or fatty acid derivatives, flexible hydrophobic structural units are introduced into its molecular chain, thereby improving its compatibility and processing adaptability in the TPU system while maintaining the structural characteristics of the polyester.

[0019] Based on the above structural design, this invention achieves multi-dimensional control of the TPU filament material structure by introducing the modified polyester component into the polyester-type thermoplastic polyurethane system, providing a new technical approach for the formulation design of TPU filaments for melt extrusion 3D printing.

[0020] Compared with the prior art, the present invention has the following beneficial effects: This invention expands the material structure design dimensions of TPU filaments by introducing modified polyester components with a specific molecular weight range into a polyester-type thermoplastic polyurethane system, thereby giving the filament system greater structural adjustability.

[0021] By introducing a controlled proportion of carbon-carbon unsaturated structures at the molecular chain ends of the modified polyester component, and combining this with fatty acid modification, the modified polyester exhibits a distinct molecular structure characteristic within the TPU system. This facilitates the formation of a stable blend system with the TPU matrix during melt processing. Through comprehensive design of the molecular weight, unsaturated end-group ratio, and fatty acid structure of the modified polyester component, this invention provides a TPU filament material structure suitable for melt extrusion 3D printing. The resulting filament can meet the basic requirements of continuous extrusion and molding processing. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the preparation process of a TPU filament for 3D printing according to the present invention; Figure 2 This is a schematic diagram of the preparation process of the modified polyester component in this invention. Detailed Implementation

[0023] The following embodiments are used to illustrate the technical solution of the present invention, but are not intended to limit the scope of protection of the present invention. Those skilled in the art can make appropriate adjustments to the types of raw materials, proportions, and process conditions without departing from the spirit of the present invention.

[0024] like Figure 1 and Figure 2 As shown, the present invention provides a method for preparing TPU filaments for 3D printing, comprising the following steps: S101, Preparation steps of modified polyester components S1011, Provide hydroxy acids and / or dicarboxylic acids and dihydroxy compounds as reaction raw materials; S1012. Polycondensation reaction is carried out under an inert atmosphere to obtain low molecular weight polyester; S1013. During or in the later stage of the polycondensation reaction, a reactant with an unsaturated structure is introduced; S1014. Carbon-carbon unsaturated end groups are formed at the ends of the resulting polyester molecular chains. S1015. The polyester after introducing carbon-carbon unsaturated end groups is subjected to fatty acid modification treatment, so that the fatty acids are grafted or block-linked to the polyester molecular chain in the form of ester bonds, thereby obtaining the modified polyester component.

[0025] Preparation steps of S102 and TPU wires S1021. Provide a polyester-type thermoplastic polyurethane and the modified polyester component obtained in step S101; S1022. Mix according to the predetermined weight ratio; S1023. The polyester-type thermoplastic polyurethane is melt-blended with the modified polyester component; S1024, and a continuous long filament TPU wire is prepared by extrusion molding process.

[0026] Without departing from the technical concept of this invention, those skilled in the art can make appropriate adjustments to the types of raw materials, proportions, and process conditions in the above steps according to actual needs. This invention provides an embodiment 1 of a TPU filament for 3D printing.

[0027] (1) Preparation of modified polyester components Lactic acid was weighed as a hydroxy acid raw material and heated to 140–180°C under nitrogen protection to carry out a polycondensation reaction. During the reaction, water was gradually removed to form a low molecular weight polyester in the reaction system.

[0028] When the number average molecular weight of the obtained polyester is controlled at about 2,000–4,000 g / mol, a small amount of maleic anhydride is added to the reaction system to introduce carbon-carbon unsaturated structures at the ends of the polyester molecular chains. The molar fraction of the unsaturated end groups at the ends of the molecular chains is controlled at about 1–5 mol.

[0029] Castor oil acid was then added to the system, and the reaction continued at 160–200°C, allowing the castor oil acid to be grafted onto the polyester molecular chain via esterification, resulting in a modified polyester component modified with fatty acids.

[0030] (2) Preparation of TPU wire Weigh 80 parts by weight of commercially available polyester-type thermoplastic polyurethane and mix it with 20 parts by weight of the above-mentioned modified polyester component. Melt blend the mixture through a twin-screw extruder, and after extrusion molding, cool and sizing to obtain continuous long filament TPU wire.

[0031] This invention provides an embodiment 2 of a TPU filament for 3D printing.

[0032] (1) Preparation of modified polyester components Adipic acid and 1,4-butanediol were weighed and heated to 180–220°C in the presence of a catalyst to carry out a polycondensation reaction. The reaction time was controlled to obtain a low molecular weight polyester with a number average molecular weight of about 3,000–6,000 g / mol.

[0033] Itaconic acid is added in the later stage of the polycondensation reaction to introduce carbon-carbon unsaturated structures at the ends of the resulting polyester molecular chains. The molar fraction of the unsaturated end groups is controlled at about 2–8 mol.

[0034] Oleic acid was then added, and an esterification reaction was carried out under elevated temperature conditions, so that the oleic acid blocks were linked to the polyester molecular chain to obtain the modified polyester component.

[0035] (2) Preparation of TPU wire Weigh 75 parts by weight of polyester-type thermoplastic polyurethane and 25 parts by weight of the above-mentioned modified polyester component, melt blend and extrude to obtain TPU wire.

[0036] This invention provides an embodiment 3 of a TPU filament for 3D printing.

[0037] (1) Preparation of modified polyester components Lactic acid, terephthalic acid, and 1,6-hexanediol are added to a reaction vessel in a predetermined molar ratio and heated to 160–220°C under nitrogen protection to carry out a copolymerization reaction. During the reaction, the generated water is gradually removed to form a low molecular weight polyester.

[0038] By controlling the reaction time, the number-average molecular weight of the obtained polyester is controlled at approximately 1,500–7,000 g / mol.

[0039] Fumaric acid is added during or in the later stages of the polycondensation reaction to introduce carbon-carbon unsaturated structures at the ends of the resulting polyester molecular chains. The molar fraction of the unsaturated end groups at the ends of the polyester molecular chains is controlled between 0.5 and 10 mol.

[0040] Stearic acid is then added to the reaction system, and the reaction continues at 170–210°C, allowing stearic acid to be grafted or block-linked onto the polyester molecular chain via esterification, resulting in a modified polyester component modified with fatty acids.

[0041] (2) Wire preparation Weigh 70-95 parts by weight of commercially available polyester-type thermoplastic polyurethane and 8-30 parts by weight of the above-mentioned modified polyester component, melt-blend them through a twin-screw extruder, and then extrude, cool and sizing them to obtain continuous long filament TPU wire.

[0042] The TPU filaments prepared by the above method exhibit good processing stability during melt extrusion. The filaments are extruded continuously with a uniform surface and no obvious bubbles or broken filaments.

[0043] This TPU filament can be stably fed in conventional melt extrusion 3D printing equipment and maintains good flexibility and molding continuity during the printing process.

[0044] Because the modified polyester component has a specific molecular weight range, terminal unsaturated structure and fatty acid modified structure, it can achieve good compatibility and dispersion in polyester thermoplastic polyurethane system, which is beneficial to adjust the processing performance of the filament and make the resulting filament suitable for a variety of 3D printing molding scenarios.

[0045] The embodiments of the present invention are given for illustrative and descriptive purposes only, and are not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described in order to better illustrate the principles and practical application of the invention, and to enable those skilled in the art to understand the invention and to design various embodiments with various modifications suitable for a particular purpose.

Claims

1. A TPU filament for 3D printing, characterized in that, The components include the following parts by weight: 70-95 parts of polyester-based thermoplastic polyurethane; The modified polyester component comprises 8 to 30 parts, wherein the modified polyester component is prepared by polycondensation reaction of hydroxy acid and / or dicarboxylic acid with dihydroxy compound, and the number average molecular weight of the modified polyester component is 1,000 to 8,000 g / mol. The modified polyester component has at least a portion of carbon-carbon unsaturated bonds at the ends of its molecular chains, and the molar fraction of the carbon-carbon unsaturated end groups at the ends of the modified polyester molecular chains is 0.5 mol% to 10 mol%. Furthermore, the modified polyester component is modified with fatty acids or fatty acid derivatives.

2. The TPU wire according to claim 1, characterized in that, The hydroxy acid is selected from one or more of lactic acid, glycolic acid, hydroxybutyric acid, and hydroxyvalerate.

3. The TPU wire according to claim 1, characterized in that, The dicarboxylic acid is selected from one or more of terephthalic acid, adipic acid, and succinic acid, and the dihydroxy compound is selected from one or more of ethylene glycol, 1,4-butanediol, and 1,6-hexanediol.

4. The TPU wire according to any one of claims 1-3, characterized in that, The carbon-carbon unsaturated bonds are derived from maleic acid, fumaric acid, itaconic acid, or their derivatives.

5. The TPU wire according to claim 1, characterized in that, The fatty acid is selected from one or more of stearic acid, oleic acid, linoleic acid, ricinoleic acid, or rosin acid.

6. The TPU wire according to claim 1 or 5, characterized in that, The fatty acids are grafted or block-linked onto the molecular chain of the modified polyester component via ester bonds.

7. The TPU wire according to claim 1, characterized in that, The polyester-type thermoplastic polyurethane is prepared by reacting polyester polyol, diisocyanate and chain extender.

8. The TPU wire according to any one of claims 1-7, characterized in that, The wire is a continuous filament material prepared by melt extrusion.

9. A method for preparing a TPU filament as described in any one of claims 1-8, characterized in that, Includes the following steps: Weigh out the polyester-type thermoplastic polyurethane and the modified polyester component according to the stated weight proportions, melt-blend them, and then extrude them to obtain TPU wire.

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