Graphene composite heating cloth and preparation process thereof

Abstract

The invention relates to the field of functional textiles, and discloses a graphene composite heating fabric and a preparation process thereof.The fabric comprises a fabric base material and a conductive heating layer arranged on the fabric base material; the conductive heating layer is prepared from amino functionalized graphene, temperature-sensitive functionalized ionic liquid and glutaraldehyde through a reaction. The preparation process comprises the following steps: mixing the components to prepare conductive ink, carrying out padding treatment on a fabric base material, finally carrying out heat treatment, forming a three-dimensional conductive network by utilizing glutaraldehyde cross-linked amino functionalized graphene, and fixing the network on the surface of a fabric fiber in a chemical bonding manner through temperature-sensitive functionalized ionic liquid. According to the scheme, the technical problems that in the prior art, due to the fact that a physical adhesive is adopted, the binding strength is low, the washing resistance is poor, and the breathability and softness of the fabric are damaged are solved, in addition, the introduced temperature-sensitive functionalized ionic liquid endows the fabric with a passive temperature self-limiting function, and the use safety is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of functional textiles, and in particular to a graphene composite heating fabric and a preparation process thereof. Background Art

[0002] In recent years, with the rapid development of flexible electronics and smart wearable device technologies, functional textiles, as an important carrier of these technologies, have received extensive research and attention. Among them, electrothermal fabrics, which can efficiently convert electrical energy into thermal energy, have become a key research direction due to their huge application potential in personal thermal management, rehabilitation therapy, outdoor clothing, and other fields.

[0003] Currently, one of the mainstream technical solutions for achieving electrothermal fabric functionality is to use a conductive coating method to composite highly conductive materials onto a fabric substrate. Graphene, due to its excellent conductivity, outstanding mechanical flexibility, and high specific surface area, is considered an ideal material for constructing high-performance electrothermal fabrics. In practice, graphene is typically dispersed in a polymer binder to form a conductive ink or slurry, which is then applied to the fabric surface through coating, padding, or other methods.

[0004] However, the bond between the conductive layer and the fabric fibers relies primarily on the physical adhesion of the adhesive, a relatively weak interfacial bonding force. Consequently, repeated daily washing, bending, and friction can cause the adhesive layer to develop microcracks or even peel, damaging the conductive network formed by the graphene. This rapidly degrades the electrical and thermal performance, making the fabric's lifespan difficult to guarantee.

[0005] Furthermore, to achieve sufficient bonding strength, a high amount of adhesive is typically used. This excessive amount of adhesive fills the natural pores between fabric fibers, forming a continuous, airtight film on the fabric surface. This structure compromises the fabric's inherent softness and breathability, reducing the wearer's comfort and limiting its application in applications such as intimate apparel.

[0006] The heating behavior of the electroheating fabric produced by this simple composite method is essentially pure resistive heating. This means that its surface temperature is entirely determined by an externally applied voltage and lacks an inherent temperature self-regulation mechanism. In actual use, voltage fluctuations or improper operation can easily lead to temperature runaway, posing a safety hazard of localized overheating or even low-temperature burns. Addressing this issue requires additional temperature sensors and complex control circuitry, which undoubtedly increases the cost, size, and complexity of the entire system.

[0007] Therefore, how to develop a new type of electrothermal fabric that has excellent electrothermal performance while also having high durability, high safety and good wearing comfort is a technical problem that needs to be urgently solved in this field. SUMMARY

[0008] The technical problem to be solved by the present application is that the graphene heating fabric in the prior art usually relies on a high polymer adhesive to attach graphene to the fabric, which leads to a decrease in the original air permeability and softness of the fabric, and the conductive layer is easily damaged after repeated washing and kneading, lacking durability. In addition, its heating temperature depends on an external temperature control system, which has safety hazards.

[0009] To solve the above technical problems, the present application provides a graphene composite heating fabric and a preparation process thereof.

[0010] The present application provides a graphene composite heating fabric in a first aspect.

[0011] The graphene composite heating fabric comprises a fabric substrate and a conductive heating layer arranged on the fabric substrate.

[0012] The conductive heating layer is prepared by a composition reaction, which comprises, by weight percentage: amine-functionalized graphene, accounting for 7.2% to 15.9%; temperature-sensitive functionalized ionic liquid, accounting for 73.5% to 90.3%; and glutaraldehyde, accounting for 2.2% to 11.8%.

[0013] In a specific embodiment, the amine-functionalized graphene is the product after the reaction of graphene oxide and 3-aminopropyltriethoxysilane; through the reaction, amine functional groups are introduced onto the surface of the graphene sheet layer.

[0014] In another specific embodiment, the temperature-sensitive functionalized ionic liquid is a copolymer of N-isopropylacrylamide and 1-allyl-3-methylimidazolium chloride; the copolymer has both temperature-sensitive segments and active groups that can react with cellulose on the molecular chain.

[0015] In the technical solution of the present application, the components are structured into a stable conductive heating layer through the following chemical reactions and physical actions: First, the amine groups on the surface of the amine-functionalized graphene react with the aldehyde groups of glutaraldehyde to form a Schiff base, thus forming a covalent bond, so that multiple amine-functionalized graphene sheet layers are crosslinked with each other to form a stable three-dimensional conductive network structure.

[0016] Secondly, the active groups in the temperature-sensitive functionalized ionic liquid chemically bond with the hydroxyl groups on the surface of the fabric substrate (such as cotton fibers), anchoring their molecular chains on the single fibers of the fabric substrate. At the same time, the flexible polymer long chains wrap and fix the graphene three-dimensional conductive network formed by the above-mentioned physical entanglement and van der Waals force, etc.

[0017] This dual chemical fixing method of internal cross-linking and external anchoring ensures extremely high bonding strength between the conductive heating layer and the fabric substrate.

[0018] In addition, since this solution does not use traditional polymer adhesives, but instead constructs the functional layer on the surface of a single fiber through in-situ chemical reaction, it can retain the original yarn gaps and porous structure of the fabric substrate.

[0019] The technical solution provided by the present invention achieves the following technical effects through the above structure: When the fabric's temperature rises to the phase transition point of the thermosensitive functionalized ionic liquid, its molecular chains undergo conformational changes and contract in volume, increasing the spacing between graphene sheets. This increase in physical spacing increases the tunnel resistance in the conductive network, leading to an increase in the overall resistance of the conductive heating layer. This increased resistance reduces the heating power, thereby suppressing further temperature increases and achieving passive temperature regulation.

[0020] A second aspect of the present invention provides a process for preparing a graphene composite heating fabric.

[0021] The preparation process is used to prepare the graphene composite heating fabric described in the first aspect above, comprising the following steps: S1. Preparation of conductive ink: Mixing amino-functionalized graphene, temperature-sensitive functionalized ionic liquid, and glutaraldehyde in deionized water to obtain conductive ink.

[0022] S2, padding: immersing the fabric substrate in the conductive ink prepared in step S1, and performing a padding treatment to obtain the treated fabric substrate.

[0023] S3, heat treatment: heat treating the treated fabric substrate at a temperature of 110-140° C. for 5-20 minutes to obtain the graphene composite heating fabric; The heat treatment is intended to provide energy to promote the cross-linking reaction between glutaraldehyde and amino-functionalized graphene, and the chemical bonding reaction between the thermosensitive functionalized ionic liquid and the fabric substrate, thereby forming a stable conductive heating layer on the fabric.

[0024] In a specific embodiment, in step S1, the amine-functionalized graphene is added to a solution of the thermosensitive functionalized ionic liquid dissolved in deionized water, and then dispersed by ultrasonic treatment; the power of the ultrasonic treatment is set to 300-500W, and the treatment time is 1-1.5 hours.

[0025] In another specific embodiment, before step S2, the method further comprises the step of performing an alkali activation treatment on the fabric substrate; The alkali activation treatment is as follows: immersing the fabric substrate in a sodium hydroxide solution with a concentration of 1.5 to 2.5 mol / L for 45 to 60 minutes; The alkali activation treatment can partially destroy the crystalline region of cellulose and expose more hydroxyl active sites, thereby improving the subsequent chemical bonding efficiency of the thermosensitive functionalized ionic liquid and the fabric substrate.

[0026] In another specific embodiment, the rolling rate of the soaking in step S2 is controlled at 70% to 95%.

[0027] In a specific embodiment, the method for preparing the amine-functionalized graphene includes: reflux reaction of graphene oxide and 3-aminopropyltriethoxysilane in a solvent to obtain the amino-functionalized graphene; The temperature of the reflux reaction is controlled at 80-95° C., and the reaction time is 12 to 24 hours.

[0028] In another specific embodiment, the preparation method of the temperature-sensitive functionalized ionic liquid comprises: N-isopropylacrylamide and 1-allyl-3-methylimidazolium chloride are copolymerized in N,N-dimethylformamide solvent under the action of an initiator to obtain the temperature-sensitive functionalized ionic liquid; The molar ratio of the N-isopropylacrylamide to the 1-allyl-3-methylimidazolium chloride is 88-92:6-8, and the temperature of the copolymerization reaction is controlled at 65-75°C.

[0029] The present invention provides a graphene composite heating fabric and a preparation process thereof, which has the following beneficial effects: 1. The graphene composite heating fabric of the present invention has excellent washability and structural durability. Its technical solution uses glutaraldehyde to cross-link amino-functionalized graphene to form a stable three-dimensional conductive network. At the same time, a temperature-sensitive functionalized ionic liquid is used as a chemical bridge, one end of which forms a covalent bond with the hydroxyl groups of the fabric substrate fibers and the other end interacts with the graphene network. This multiple chemical bond locking method replaces traditional physical adhesion, forming a strong bond between the conductive heating layer and the fabric substrate. Therefore, it can maintain its structural integrity and stable electrical properties after repeated washing and bending.

[0030] 2. The graphene composite heating fabric of the present invention possesses an inherent passive temperature control function. This function originates from the thermosensitive functionalized ionic liquid used. This material contains N-isopropylacrylamide units and has a specific phase transition temperature. When the heating temperature of the fabric reaches this phase transition temperature, its polymer chains undergo conformational contraction, physically increasing the spacing between graphene sheets in the conductive network. This increased spacing causes the tunnel resistance in the conductive path to increase, raising the total resistance of the conductive heating layer. This automatically reduces the heating power based on the principle of electrothermal conversion, achieving a passive limit on the maximum temperature of the fabric, thus improving user safety without relying on external temperature control components.

[0031] 3. The preparation process of the present invention chemically bonds the functional components directly to the surface of individual fibers of the fabric substrate through a padding process followed by a heat curing step. This method avoids the use of polymer adhesives, which form a continuous, dense film in traditional coating processes, thereby preserving the original inter-yarn gaps and porous structure of the fabric substrate. This structural feature avoids the problems of decreased air permeability and overall stiffening of the fabric caused by clogged pores. The final product maintains its original softness and breathability while providing electric heating functionality, thereby ensuring the product's physical comfort. DETAILED DESCRIPTION

[0032] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0033] 1. Experimental Materials and Reagents The sources and specifications of the main raw materials and reagents used in the following examples and comparative examples are as follows. Reagents not specifically specified are all commercially available products of analytical grade or higher.

[0034] 3-Aminopropyltriethoxysilane: CAS number: 919-30-2; N-isopropylacrylamide: CAS number: 2210-25-5; Glutaraldehyde: CAS No.: 111-30-8; Sodium hydroxide: CAS number: 1310-73-2; N,N-Dimethylformamide: CAS number: 68-12-2.

[0035] Example 1-3: Example 1: (1) Preparation of conductive ink: The following weight percentages were mixed based on solid content: 15.9% amine-functionalized graphene, 79.4% thermosensitive functionalized ionic liquid, and 4.7% glutaraldehyde. These components were added to 100 g of deionized water and ultrasonically treated at 400 W for 1 hour to allow for thorough dispersion and mixing. The mixture was then mechanically stirred for 30 minutes to obtain the conductive ink.

[0036] (2) Fabric pretreatment: Soak the pure cotton fabric substrate in a 1.5 mol / L sodium hydroxide solution for 45 minutes, take it out and wash it with deionized water until it is neutral, and dry it for later use.

[0037] (3) Padding and heat treatment: The pretreated fabric substrate is immersed in the conductive ink prepared in step (1), and then padded by a padder, with the padding ratio set at 70%. The padded fabric is placed in an oven at 110°C for 20 minutes, and then taken out and cooled to obtain a graphene composite heating fabric.

[0038] Example 2: A graphene composite heating fabric is prepared. The preparation method is basically the same as that of Example 1, except that: In the preparation of the conductive ink in step (1), the weight percentage of the solid content of each component is: 10.0% of amino-functionalized graphene (f-GO), 85.0% of thermosensitive functionalized ionic liquid, and 5.0% of glutaraldehyde.

[0039] In step (2), the concentration of the sodium hydroxide solution is 2.0 mol / L, and the soaking time is 50 minutes.

[0040] In step (3), the rolling ratio is 80%, the heat treatment temperature is 120°C, and the time is 10 minutes.

[0041] Example 3: A graphene composite heating fabric is prepared. The preparation method is basically the same as that of Example 1, except that: In the preparation of the conductive ink in step (1), the weight percentage of the solid content of each component is: 7.2% of amino-functionalized graphene (f-GO), 87.0% of thermosensitive functionalized ionic liquid, and 5.8% of glutaraldehyde.

[0042] In step (2), the concentration of the sodium hydroxide solution is 2.5 mol / L, and the soaking time is 60 minutes.

[0043] In step (3), the rolling ratio is 95%, the heat treatment temperature is 140°C, and the time is 5 minutes.

[0044] Comparative Examples 1-3: Comparative Example 1: Compared with Example 2, the difference is that glutaraldehyde is not added in the preparation of the conductive ink.

[0045] Comparative Example 2: Compared with Example 2, the difference is that the temperature-sensitive functionalized ionic liquid is not added in the preparation of the conductive ink, but is replaced by polyurethane accounting for 85.0% of the total solid content.

[0046] Comparative Example 3: Compared with Example 2, the difference is that in the preparation of the conductive ink, the weight percentage of the solid content of each component is adjusted to: 28.6% of the amino-functionalized graphene, 57.1% of the temperature-sensitive functionalized ionic liquid, and 14.3% of the glutaraldehyde.

[0047] Performance test example 1-2: Test Example 1: Conductivity, heat generation and washability tests (1) Test method: a) Initial conductivity test: Use a four-probe tester (model: RTS-8) to measure the sheet resistance of each sample at five randomly selected points on the surface, and take the average value.

[0048] b) Thermal Performance Test: Connect electrodes to both ends of a 5 cm × 5 cm sample and apply a 5 V DC voltage. Use an infrared thermal imager (FLIRE6) to record the temperature at the center of the sample until the temperature stabilizes. The stable temperature is recorded.

[0049] c) Washability Test: Samples were placed in a standard launder-ometer and washed 10 times according to AATCC 61-2013. After each wash cycle, the samples were dried at 60°C and their sheet resistance was remeasured. The change in sheet resistance after 10 wash cycles was calculated. Change (%) = (Post-wash resistance - Pre-wash resistance) / Pre-wash resistance × 100%.

[0050] Table 1: Test data of electrical conductivity, heat generation and washability (2) Test results: As can be seen from the data in Table 1, the samples prepared in Examples 1-3 all have low initial sheet resistance. Due to the lack of glutaraldehyde as a crosslinking agent in Comparative Example 1, the sheet resistance of the sample prepared therefrom increased significantly after undergoing a water washing cycle, indicating that its conductive layer structure is unstable. This is because the aldehyde groups of glutaraldehyde react with the amine groups on the surface of the amino-functionalized graphene, forming covalent crosslinks, thereby constructing a stable three-dimensional conductive network. Without this crosslinking effect, the graphene sheets are only bonded by physical adsorption and are easily detached under the mechanical action of water flow.

[0051] After 10 wash cycles, the sheet resistance change rates of the samples in Examples 1-3 all remained low, demonstrating the strong bond between the conductive layer and the textile substrate. This strong bond is attributed to the chemical bonding of the thermosensitive functionalized ionic liquid with the hydroxyl groups on the cellulose surface of the textile substrate, while its molecular chains interact with the graphene network, stably anchoring the conductive network to the textile surface. In Comparative Example 3, insufficient thermosensitive functionalized ionic liquid was used, resulting in a reduced anchoring effect, and the resistance change rate after washing was significantly higher than that of the examples.

[0052] Test Example 2: Passive Temperature Control Performance and Fabric Physical Properties Test (1) Test method: (a) Passive temperature control test: Electrodes are connected to the two ends of a 5 cm × 5 cm sample. A high constant voltage (10 V) is applied. An infrared thermal imager is used to continuously record the temperature change at the center of the sample over time until the temperature stops rising significantly and reaches a plateau. The stable temperature during this plateau is then recorded.

[0053] (b) Air permeability test: The air permeability of the sample was tested at a pressure difference of 100 Pa using a fabric air permeability tester (model: YG461E) in accordance with GB / T5453-1997.

[0054] (c) Softness test: A fabric stiffness tester (model: YG(B)022D) was used to measure the bending length of the sample. The smaller the bending length, the softer the fabric.

[0055] Table 2: Passive temperature control and physical performance test data (2) Test results: The test results in Table 2 show that the temperature of the samples of Examples 1-3 can automatically stabilize within a certain numerical range (54-57°C) under a voltage of 10V. This phenomenon is attributed to the temperature-sensitive functionalized ionic liquid in the conductive heating layer. When the temperature rises to near its phase transition point, the conformation of its molecular chain changes and causes volume contraction, thereby increasing the physical spacing between the graphene sheets. The increase in this spacing increases the tunnel resistance in the conductive network, resulting in an increase in the total resistance of the conductive heating layer, and the heating power decreases accordingly, thereby inhibiting further temperature increases. Since Comparative Examples 1 and 2 do not contain or contain the temperature-sensitive functionalized ionic liquid, they do not have this structural change mechanism, so the temperature continues to rise, posing a safety hazard.

[0056] In terms of fabric physical properties, the samples of embodiments 1-3 all maintained a high air permeability and a low bending length, indicating that they did not significantly sacrifice the air permeability and softness of the fabric while obtaining the electrothermal function. This is because the present technical solution constructs the conductive network on the surface of the single fiber through in-situ chemical bonding, thereby preserving the original porous structure of the fabric substrate between the fibers and between the yarns. In contrast, as shown in Comparative Example 2, the traditional process using polyurethane as the adhesive, the polymer adhesive will fill and close these key pores during the finishing process, forming a continuous, non-permeable polymer film on the surface and inside of the fabric. The presence of this film not only hinders the circulation of air, leading to a significant reduction in air permeability, but also limits the relative movement of the fibers and yarns, increasing the bending stiffness of the entire fabric composite, macroscopically manifested as a hard hand feel and a decrease in softness. Therefore, the preparation method of the present application ensures the maintenance of the physical comfort of the final product.

Claims

1. A graphene composite heating fabric, characterized in that: include: A fabric substrate, and a conductive heating layer disposed on the fabric substrate; The conductive heating layer is prepared from the following components, calculated by weight percentage: Amine-functionalized graphene, accounting for 7.2% to 15.9%; Thermosensitive functionalized ionic liquids, accounting for 73.5% to 90.3%; and glutaraldehyde, ranging from 2.2% to 11.8%.

2. The graphene composite heating fabric according to claim 1, characterized in that: The amino-functionalized graphene is a product of the reaction between graphene oxide and 3-aminopropyltriethoxysilane.

3. The graphene composite heating fabric according to claim 1, characterized in that: The temperature-sensitive functionalized ionic liquid is a copolymer of N-isopropylacrylamide and 1-allyl-3-methylimidazolium chloride.

4. A process for preparing the graphene composite heating fabric according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1. Preparation of conductive ink: Mixing amine-functionalized graphene, temperature-sensitive functionalized ionic liquid, and glutaraldehyde in deionized water to obtain conductive ink; S2, padding: immersing the fabric substrate in the conductive ink prepared in step S1, and performing a padding treatment to obtain the treated fabric substrate; S3. Heat treatment: heat-treating the treated fabric substrate at a temperature of 110-140° C. for 5-20 minutes to obtain the treated graphene composite heating fabric.

5. The preparation process of a graphene composite heating fabric according to claim 4, characterized in that: In step S1, the amine-functionalized graphene is added to a solution of the thermosensitive functionalized ionic liquid dissolved in deionized water, and then dispersed by ultrasonic treatment; The power of the ultrasonic treatment is 300-500W, and the treatment time is 1-1.5 hours.

6. The preparation process of a graphene composite heating fabric according to claim 4, characterized in that: The fabric substrate described in step S2 is a fabric substrate that has been subjected to alkali activation treatment; The alkali activation treatment comprises: immersing the fabric substrate in a sodium hydroxide solution with a concentration of 1.5 to 2.5 mol / L for 45 to 60 minutes.

7. The preparation process of a graphene composite heating fabric according to claim 4, characterized in that: In step S2, the rolling rate is 70% to 95%.

8. The preparation process of a graphene composite heating fabric according to claim 4, characterized in that: The preparation method of the amino-functionalized graphene comprises: subjecting graphene oxide and 3-aminopropyltriethoxysilane to a reflux reaction in a solvent to obtain the amino-functionalized graphene; The temperature of the reflux reaction is 80-95° C., and the reaction time is 12 to 24 hours.

9. The preparation process of a graphene composite heating fabric according to claim 4, characterized in that: The preparation method of the thermosensitive functionalized ionic liquid comprises: copolymerizing N-isopropylacrylamide and 1-allyl-3-methylimidazolium chloride in an N,N-dimethylformamide solvent under the action of an initiator to obtain the thermosensitive functionalized ionic liquid; The molar ratio of the N-isopropylacrylamide to the 1-allyl-3-methylimidazolium chloride is 88-92:6-8, and the temperature of the copolymerization reaction is 65-75°C.

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