Self-healing ink and preparation method thereof

Abstract

The invention provides a self-healing ink and a preparation method thereof, and the preparation method comprises the following steps: reacting 4-azobenzene furan with maleic anhydride at 60-80 DEG C for 3-5 hours to form a dynamic cross-linked prepolymer; the preparation method comprises the following steps: dispersing graphene nanosheets and titanium dioxide nanoparticles in dioxane through ultrasonic treatment at the power of 200-500W until the particle size is less than or equal to 100nm; and stirring the prepolymer and the dispersion liquid at 80-90 DEG C for 2-4 hours, and adjusting the solid content to 30% to obtain the self-healing ink. The self-healing ink disclosed by the invention realizes efficient self-healing, function integration and environment-friendly adaptation through dynamic chemical bond design, nano material collaboration and process optimization, and shows remarkable technical advantages and market potential in the fields of flexible electronics, intelligent packaging and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of inks, and particularly to a self-healing ink and a preparation method thereof. Background Art

[0002] With the rapid development of fields such as flexible electronics, smart wearable devices, and automotive electronics, higher requirements are put forward for the durability and reliability of functional inks. Traditional ink materials are prone to cracking or attenuation of electrical conductivity under mechanical stress or environmental aging, resulting in device failure. In recent years, self-healing technology has provided a new direction to solve this problem, but existing solutions still have significant limitations.

[0003] Early self-healing inks mostly relied on physical mechanisms, such as achieving local repair through photothermal effects. However, such methods have the following problems: 1. The healing conditions are harsh, requiring precise control of the light source wavelength and power. Excessive energy input is likely to accelerate the aging of the resin; 2. The interfacial bonding force after repair is weak and is only applicable to microcracks. Therefore, there is an urgent need to develop a new type of self-healing ink with fast self-healing ability to break through the bottleneck of existing technologies and meet the needs of high-value-added fields such as flexible electronics. Summary of the Invention

[0004] In view of this, the present invention proposes a self-healing ink and a preparation method thereof.

[0005] The technical solution of the present invention is realized as follows: The present invention provides a preparation method of a self-healing ink, including the following steps:

[0006] Step 1: React 4-azophenylfuran with maleic anhydride at 60 - 80 °C for 3 - 5 hours to form a dynamic crosslinked prepolymer;

[0007] Step 2: Disperse graphene nanosheets and titanium dioxide nanoparticles in dioxane by ultrasonic treatment with a power of 200 - 500 W until the particle size ≤ 100 nm;

[0008] Step 3: Stir the prepolymer in Step 1 and the dispersion in Step 2 at 80 - 90 °C for 2 - 4 h, and adjust the solid content to 30% to obtain the self-healing ink.

[0009] In Step 1, 4-azophenylfuran and maleic anhydride form a dynamic covalent bond network through the Diels - Alder reaction. This reaction is reversible, triggering the breakage and recombination of reversible bonds at 60 - 80 °C, endowing the ink with self-healing ability. The azobenzene group of 4-azophenyl undergoes cis - trans isomerization under 365 nm ultraviolet light, further accelerating the dynamic bond recombination and achieving rapid repair within 30 seconds.

[0010] In some embodiments, in step one, a mixed catalyst is further added. The mixed catalyst is obtained by mixing potassium bromide and peracetic acid in a molar ratio of 1:1. After the reaction, the pH is adjusted to 4.5 - 6.8.

[0011] The synergistic catalytic effect of potassium bromide and peracetic acid (1:1) inhibits side reactions (such as thiourea decomposition) and stabilizes reaction intermediates by adjusting the pH to 4.5 - 6.8, thereby enhancing the dynamic crosslinking efficiency. The acidic environment promotes the ring-opening reaction of maleic anhydride and enhances the interfacial bonding between the prepolymer and graphene.

[0012] In some embodiments, step three further includes grinding with a ball mill until the ink fineness reaches 20 - 40 μm.

[0013] 200 - 500W ultrasonic treatment disperses graphene - TiO₂ uniformly in dioxane (particle size ≤ 100 nm), avoiding nanoparticle aggregation. Subsequent ball milling to a fineness of 20 - 40 μm ensures that the ink fluidity is suitable for screen printing / inkjet printing processes and reduces surface defects of the coating.

[0014] In some embodiments, the dosage of the graphene nanosheets is 30 - 70% of the total mass of the self - healing ink.

[0015] The graphene nanosheets form a three - dimensional conductive network, endowing the ink with high electrical conductivity and anti - bending properties. Titanium dioxide nanoparticles, as photocatalysts, excite electron - hole pairs under ultraviolet light, accelerate the recombination of dynamic bonds, and decompose pollutants to achieve self - cleaning.

[0016] In some embodiments, the surface of the graphene nanosheets is modified with polyurethane segments. The polyurethane segments are obtained by grafting reaction of an isocyanate - terminated polyurethane prepolymer with the hydroxyl groups on the graphene surface. The reaction temperature is 70 - 90 °C and the time is 2 - 3 hours.

[0017] Grafting on the graphene surface with an isocyanate - terminated polyurethane prepolymer enhances its compatibility with the resin matrix. The flexible segments of polyurethane disperse stress through hydrogen bonds and physical entanglement, inhibit crack propagation, and improve the coating adhesion at the same time.

[0018] In some embodiments, the substitution degree of 4 - azophenylfuran is 0.5 - 1.2 mol / kg.

[0019] In some embodiments, the D50 of the titanium dioxide nanoparticles is 10 - 50 nm, and the dosage of the titanium dioxide nanoparticles is 5 - 10% of the total mass of the self - healing ink.

[0020] In some embodiments, after the ink is coated on the substrate, it is cured at 105 °C for 30 seconds to form a coating with a dry weight of 1.5 ± 0.05 g / m 2 ².

[0021] Cured at 105 °C for 30 seconds, a dense coating (dry weight 1.5 ± 0.05 g / m 2 ) was formed by thermally initiated dynamic bond crosslinking. Short-time curing at high temperature avoided thermal degradation of the resin matrix and balanced the flexibility and hardness of the coating.

[0022] In a second aspect of the present invention, a self-healing ink prepared by the above preparation method is also provided.

[0023] In a third aspect of the present invention, a use of the above self-healing ink is also provided, which is used for intelligent packaging electronic tags and can be repaired within 30 s by ultraviolet light irradiation with a wavelength of 365 nm.

[0024] The present invention has the following beneficial effects compared with the prior art:

[0025] Through dynamic chemical bond design, nanomaterial synergy and process optimization, the self-healing ink of the present invention realizes efficient self-healing, function integration and environmental protection adaptation, and shows significant technical advantages and market potential in the fields of flexible electronics, intelligent packaging, etc. Detailed Embodiments

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0027] Unless otherwise defined, all technical terms and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the embodiments of the present invention belong. If the definitions stated in this part are contrary to or inconsistent with the definitions stated in the patents, patent applications, published patent applications and other publications incorporated herein by reference, the definitions listed in this part shall prevail over the definitions incorporated herein by reference.

[0028] The methods used in the following examples are all conventional methods unless otherwise specified. The materials, reagents and instruments used are all conventional materials, reagents and instruments in the art unless otherwise specified, and those skilled in the art can obtain them through commercial channels.

[0029] When an equivalent, concentration or other value or parameter is expressed as a range, a preferred range or a range defined by a series of upper preferred values and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed individually. For example, when the range "1 to 5" is disclosed, the described range should be interpreted as including the ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values and all integers and fractions within the range. In the specification and claims of this application, range limitations may be combined and / or interchanged, and if not otherwise stated, these ranges include all sub-ranges contained therein.

[0030] Example 1

[0031] Raw material ratio:

[0032] 4-Azophenylfuran (substitution degree 1.0 mol / kg): 120 g

[0033] Maleic anhydride: 80 g

[0034] Mixed catalyst (KBr: peracetic acid = 1:1 molar ratio): KBr 12 g + peracetic acid 15 g

[0035] Solvent: dioxane 200 mL

[0036] Reaction conditions: React at 70 °C for 4 hours and adjust the pH to 5.5.

[0037] Nanomaterial dispersion

[0038] Polyurethane-modified graphene nanosheets (accounting for 50% of the total ink mass): 500 g

[0039] Modification process: React isocyanate-terminated polyurethane prepolymer (100 g) with graphene (400 g) at 80 °C for 2.5 hours.

[0040] Titanium dioxide nanoparticles (D50 = 30 nm, accounting for 5% of the total ink mass): 50 g

[0041] Dispersion solvent: dioxane 300 mL

[0042] Dispersion process: Ultrasonic treatment at 400 W until the particle size ≤ 100 nm

[0043] Ink compounding and curing

[0044] Mix the prepolymer and the dispersion, stir at 80 - 90 °C for 3 hours, and adjust the solid content to 30% (total mass 1000 g).

[0045] Grinding process: Ball mill to a fineness of 30 μm (ball mill rotation speed 200 rpm, time 2 hours).

[0046] Curing conditions: Bake at 105 °C for 30 seconds, dry weight 1.5 g / m 2 。

[0047] Comparative Example 1

[0048] In this comparative example, based on Example 1, 4-azophenylfuran was replaced with a common epoxy resin crosslinking agent (120 g), and the catalyst was omitted.

[0049] Raw materials and process:

[0050] Prepolymer: Epoxy resin (120 g) and maleic anhydride (80 g) were reacted at 70 °C for 4 hours.

[0051] The remaining steps were the same as in Example 1.

[0052] Example 2

[0053] In this example, based on Example 1, the proportion of graphene nanosheets was adjusted to 70%: 700 g (modified with polyurethane); titanium dioxide nanoparticles (D50 = 10 nm, proportion 10%): 100 g. The remaining conditions were the same as in Example 1

[0054] Comparative Example 2

[0055] In this comparative example, based on Example 1, unmodified graphene (500 g) was used, and the polyurethane grafting step was omitted. The remaining conditions were the same as in Example 1.

[0056] Example 3

[0057] In this example, based on Example 1, the pH was adjusted to 6.0 after the prepolymer reaction. The remaining conditions were the same as in Example 1.

[0058] Comparative Example 3

[0059] In this comparative example, based on Example 1, the pH was adjusted to 3.0 after the prepolymer reaction. The remaining conditions were the same as in Example 1.

[0060] Comparative Example 4

[0061] Microcapsule preparation:

[0062] Core material: Dicyclopentadiene (DCPD) 100 g;

[0063] Wall material: Urea-formaldehyde resin (urea:formaldehyde = 1:2) was coated by in-situ polymerization, and the microcapsule diameter was 50 - 200 μm.

[0064] Catalyst dispersion:

[0065] 5 g of Grubbs catalyst (second-generation Ru catalyst) was dispersed in the epoxy resin matrix.

[0066] Coating preparation:

[0067] Microcapsules (10% mass fraction) and catalyst (0.5% mass fraction) were dispersed in the epoxy resin matrix (1000 g).

[0068] Curing conditions: 80 °C / 2 hours, dry coating weight 1.8 g / m 2 。

[0069] The self-healing efficiency test, electrical properties and durability test, chemical resistance test, and mechanical properties test were respectively carried out on the cured inks prepared in the above examples and comparative examples.

[0070] Self-healing efficiency test: According to the T / GDEIA17—2021 standard, after scratching with a copper brush (copper wire diameter 0.2 mm), the repair time was recorded under 365 nm ultraviolet light irradiation (assisted by 50 - 60 °C hot air);

[0071] Electrical properties and durability test: The change rate of resistance after 100,000 times of bending (curvature radius 3 mm) was tested according to GB / T 2792-2014.

[0072] Chemical resistance test: Salt spray test (5% NaCl solution, 35 °C) for 48 hours according to GB / T 30790.6, and the spread of scratch corrosion (M value) was observed.

[0073] Mechanical properties test: The tensile resilience rate and elongation at break were tested according to GB / T 528-2009.

[0074] The test results are shown in the following table:

[0075]

[0076]

[0077] From the comparison between Example 1 and Comparative Example 1, it can be seen that in Example 1, through the synergy of photo / thermal dual-responsive dynamic bonds (4-azophenylfuran) and TiO2 photocatalysis, the self-healing time was shortened to 30 seconds (traditional physical cross-linking required 30 minutes), and the conductive recovery rate was increased to 99.2% (compared with 65%).

[0078] From the comparison between Example 1 and Comparative Example 2, it can be seen that in Example 1, by modifying graphene with polyurethane segments, the tensile strength recovery rate was 96% (compared with 82%), and the conductivity was 17000 S / cm (compared with 12000 S / cm).

[0079] It can be seen from the comparison between Example 1 and Comparative Example 3 that in Example 1, the dynamic bond crosslinking degree is 95% at pH = 5.5 (compared with 60% at pH = 3.0), and the M value of salt spray resistance is -0.15 mm (corrosion does not spread).

[0080] The present invention realizes ultra-fast self-healing (30 seconds) and high conductive recovery rate (>99%) through the synergy of dynamic bonds and photocatalysis, which is significantly better than the solutions of traditional physical / microcapsule systems.

[0081] The modification of graphene with nano-interfacial polyurethane solves the contradiction between dispersibility and mechanics.

[0082] Short-time curing and high-precision processes meet the mass production requirements of flexible electronics.

[0083] The design of the chemical stability of dynamic bonds is applicable to harsh environments.

[0084] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of a self-healing ink, characterized in that, It includes the following steps: Step 1: React 4-azophenylfuran with maleic anhydride at 60 - 80 °C for 3 - 5 hours to form a dynamic crosslinked prepolymer; Step 2: Disperse graphene nanosheets and titanium dioxide nanoparticles in dioxane by ultrasonic treatment with a power of 200 - 500 W until the particle size is ≤100 nm; Step 3: Stir the prepolymer from Step 1 and the dispersion from Step 2 at 80 - 90 °C for 2 - 4 h, and adjust the solid content to 30% to obtain a self-healing ink.

2. The preparation method of the self-healing ink according to claim 1, wherein, In Step 1, a mixed catalyst is also added. The mixed catalyst is obtained by mixing potassium bromide and peracetic acid in a molar ratio of 1:1, and after the reaction, the pH is adjusted to 4.5 - 6.

8.

3. The preparation method of the self-healing ink according to claim 1, characterized in that Step 3 also includes grinding with a ball mill until the ink fineness is 20 - 40 μm.

4. The preparation method of the self-healing ink according to claim 1, characterized in that, The dosage of the graphene nanosheets is 30 - 70% of the total mass of the self-healing ink.

5. The preparation method of the self-healing ink according to claim 1, wherein, The surface of the graphene nanosheets is modified with polyurethane segments, and the polyurethane segments are obtained by grafting reaction of an isocyanate-terminated polyurethane prepolymer with the hydroxyl groups on the graphene surface. The reaction temperature is 70 - 90 °C and the time is 2 - 3 hours.

6. The preparation method of the self-healing ink according to claim 1, characterized in that, The substitution degree of the 4-azophenylfuran is 0.5 - 1.2 mol / kg.

7. The preparation method of the self-healing ink according to claim 1, wherein, The D50 of the titanium dioxide nanoparticles is 10 - 50 nm, and the dosage of the titanium dioxide nanoparticles is 5 - 10% of the total mass of the self-healing ink.

8. The preparation method of the self-healing ink according to claim 1, wherein, The ink is cured at 105 °C for 30 seconds after being coated on the substrate, forming a coating with a dry weight of 1.5 ± 0.05 g / m 2 ².

9. A self-healing ink, characterized in that, Prepared by the preparation method described in any one of claims 1 - 8.

10. Use of the self-healing ink according to claim 9, wherein, For intelligent packaging electronic tags, it can repair wear within 30 s by ultraviolet light irradiation with a wavelength of 365 nm.

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