CROSS REFERENCE TO THE RELATED APPLICATIONS

This application is the national phase entry of International Application No. PCT/CN2019/129799, filed on Dec. 30, 2019, which is based upon and claims priority to Chinese Patent Application No. 201910047850.X, filed on Jan. 18, 2019, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to the technical field of three-dimensional (3D) printing, and in particular, to a functional ink suitable for 3D printing and a preparation method thereof.

BACKGROUND

3D printing technology, also known as additive manufacturing technology, is a way of manufacturing layer-by-layer by adding materials based on 3D model data, which is completely opposite to the traditional material processing method. An advantage of 3D printing is that one is able to construct complex structures having arbitrary shapes, and realize the rapid and efficient production of three-dimensional structure. Due to its unique characteristics of dimension reduction and rapid layer-by-layer processing, 3D printing provides unlimited possibilities for the next generation of manufacturing technology. Additive manufacturing is the development direction supported by the 13th Five-Year Plan in China.

In recent years, 3D printing technology has developed rapidly in the preparation of structural materials, but it has fallen short with respect to the manufacture of functional devices having special utility and performance. Unlike shapes, functions are difficult to realize via printing. As a result, there is a desire to meet this urgent need in 3D printing industry. The existing 3D printing technologies mainly include fused deposition modeling (FDM), selective laser melting (SLM), stereolithography appearance (SLA), and direct ink writing (DIW). The DIW technology exhibits great potential in the application of preparing complex functional devices because of its wide selection of printing materials, easy printing at room temperature, simple procedure and low cost. Functional ink is the key that determines its processability and the final performance of the printed functional devices, and it is also the biggest difficulty of the direct ink writing 3D printing process.

Currently, there are numerous problems with existing methods for preparing 3D printing functional ink, including: 1. it is difficult to prepare a conductive ink suitable for 3D printing with uniform composition and stable dispersion at high concentrations; 2. the content of active substances in the ink is low, and the functional performance of printed devices is poor; 3. the interaction between layers obtained by the layer-by-layer printing is weak with inevitably created interfacial resistance, and the performance of the devices therefore decays rapidly with the increase of layers.

SUMMARY

In view of the above-mentioned deficiencies in the prior art, the present invention provides a functional ink suitable for 3D printing and a preparation method thereof. The new ink and method solve the problem that the existing ink has no self-healing function at room temperature, and the printed products have poor mechanical coalescence between layers and large interface resistance.

In order to achieve the above-mentioned objective, the technical solution adopted by the present invention to solve the technical problem is as follows.

A functional ink suitable for 3D printing includes the following components in parts by weight:

0.5-1.5 parts of a regulator, 1-5 parts of a conductive material, 0.1-0.5 parts of a crosslinking agent, 0.1-0.5 parts of a catalyst, and 10-80 parts of a solvent.

The regulator provides a reversible dynamic intermolecular interaction or a reversible dynamic intramolecular interaction at room temperature.

Further, the functional ink also includes 0-10 parts of a functional nanomaterial.

Further, the reversible dynamic interaction is realized by reversible dynamic bonds, and the reversible dynamic bonds are covalent bonds, hydrogen bonds or ion coordination bonds.

Further, the regulator is at least one selected from the group consisting of chitosan, polyvinyl alcohol, nanocellulose, polyethylene glycol, catechin and tannic acid.

Further, the conductive material is a conductive carbon material, a conductive polymer or a conductive metal particle.

Further, the crosslinking agent is polymaleic acid, citric acid, propane-1,2,3-tricarboxylic acid, butane-1,2,3,4-tetracarboxylic acid, glutaraldehyde or borate.

Further, the catalyst is sulfuric acid, hydrochloric acid, phosphoric acid, phosphomolybdic acid, potassium bisulfate, aluminum chloride, ferric chloride, sodium bisulfate, sodium hypophosphite, sodium acetate, aluminium oxide, silicon dioxide, zinc oxide or titanium dioxide.

Further, the functional nanomaterial is at least one selected from the group consisting of a metal oxide, a metal sulfide, a transition metal carbide, a transition metal nitride, an inorganic nonmetallic element, a redox small molecule, a phosphate and a titanate, which provide different functionalities such as conductivity, charge storage ability, and magnetism.

Further, the functional nanomaterial is at least one selected from the group consisting of SnO2, Fe3O4, MnO2, MoS2, SnS2, MXenes, TiNx, MoNx, Si, Sn, Viologen, LiFePO4and Li4Ti5O12.

Further, the solvent is water, ionic liquid, acetic acid, urea, thiourea, N, N-dimethylacetamide, dimethyl sulfoxide or N-methylmorphine.

A preparation method of the functional ink suitable for the 3D printing includes the following steps.

Under conditions of 20-35° C. and 8000-30000 r/min, the components are mixed and stirred for 20-60 min according to the formulation.

The specific process of the 3D printing with the functional ink suitable for the 3D printing is as follows:

(1) loading the prepared functional ink into a syringe barrel of a 3D printer, and then running a pneumatically driven dispenser at a speed of 5-10 mm/s;

(2) under a condition of 120-200° C., heating the product obtained in step (1) for 30-100 min, and washing followed by drying at 50-100° C. for 12-30 h.

Further, a heating time in step (2) is 40-60 min.

Further, a drying temperature in step (2) is 60-90° C., and a drying time is 20-24 h.

The advantages of the present invention are as follows.

1. The regulator, which enables the reversible dynamic intermolecular interaction or reversible dynamic intramolecular interaction at room temperature, is added to the formulation. The regulator contributes to reversible bonds or intermolecular dynamic interaction at room temperature, so that the ink prepared by the present invention has a self-healing function at room temperature. Therefore, when the 3D printing is carried out, the autonamous self-healing effect of the ink at room temperature eliminates the interface resistance between printing layers, enhances the interaction between the printed layers, and effectively improves the electrical, magnetic, electrochemical properties of the functional devices printed by using the ink.

2. The crosslinking and catalyst agents promote the crosslinking reaction between polymer chains in the formulation that fosters the development of a sturdy reticulate network with desired mechanical properties.

3. According to actual needs of the products to be prepared, the functional nanomaterials with different properties are selected to prepare the functional inks with different functions and applications.

4. The ink prepared by the present invention has excellent electrical conductivity, self-healing and multiple functions, which can be widely applied in the fields of functional devices such as energy storage, electromagnetic shielding and stress sensing.

