A method for producing a temperature visualizing yarn

Abstract

The application discloses a temperature visualized yarn, the outer surface of the yarn is provided with a thermochromic ink layer, the inside of the thermochromic ink layer is provided with fibers, and carbon-based conductive composite ink is arranged between the fibers. The application further discloses a preparation method of the temperature visualized yarn, and the method is simple in operation, mild in conditions, controllable in yarn diameter form and suitable for large-scale production. The obtained spiral stretchable electrothermal yarn has excellent stretchability and strain electrical stability, so that the electrothermal yarn can maintain excellent electrothermal stability in the stretching deformation process. In the stretching process, the yarn temperature can be accurately reflected through color change, and the application provides a basis for yarn functionalization and intelligentization, and exhibits great application value in the fields of temperature management, intelligent wearable and flexible display.

Description

Technical Field

[0001] This invention belongs to the field of fiber material technology, and specifically relates to a method for preparing temperature-visible yarn. Background Technology

[0002] In recent years, with the development of wearable technology, multifunctionality has become a major trend in flexible electronic devices. Personal health and thermal comfort, as fundamental requirements in daily life, are increasingly important for wearable electronic products. To promote the rapid development of this hot field, it is crucial to develop wearable electronic products that are flexible, durable, stretchable, and thermally stable. Flexible electrothermal yarns are considered an ideal substrate for developing flexible, breathable, and wearable heaters, better suited to the human body and meeting diverse application requirements. Currently, researchers have prepared flexible conductive yarns by depositing metal nanomaterials, conductive polymers, and carbon nanomaterials onto traditional textile yarns such as cotton and polyester. These yarns not only maintain good flexibility but also possess excellent abrasion and flexural strength. However, most of these flexible heaters are not stretchable or exhibit severely degraded heating performance under stretching due to the decomposition of the conductive network. For example, Chinese Patent Publication No. CN113512816A develops a machine-washable and knittable electrothermal composite yarn. This method is simple to operate and machine-washable and knittable, but its stretchability is poor, and performance is lost under excessive stretching, limiting its practical application prospects.

[0003] Wearable electronic products that regulate human thermal comfort are often referred to as "a second skin," thus requiring a certain degree of self-temperature sensing and self-regulation capabilities. While current electrothermal yarns can precisely control the heating temperature by adjusting the input voltage, temperature changes are not directly perceptible to humans, and this unvisualized temperature rise can easily cause direct harm. Electrothermal-chromic yarns, with their simple structure, can achieve controllable and reversible color changes under the stimulation of an external electric field, thereby making temperature visible. However, current stretchable thermochromic yarns are sensitive to changes in resistance; stretching causes changes in resistance, resulting in abrupt changes in heating temperature, affecting practical applications. For example, Chinese patent CN107475840 describes a stretchable electrothermal-chromic fiber prepared through a layer-by-layer impregnation method. Under different degrees of stretching, the fiber resistance changes, causing changes in heating temperature and color, failing to accurately reflect the heating temperature. Therefore, designing an electrothermal yarn that is simple to manufacture, durable, stretchable, and whose electrothermal and thermochromic properties remain stable during stretching is a problem that engineers urgently need to solve. Summary of the Invention

[0004] The purpose of this invention is to solve the technical problems of how to obtain a temperature-visible electrothermal yarn and its preparation method, so that the method is simple to operate, has mild conditions, low cost, and is suitable for large-scale production; and to make the prepared temperature-visible electrothermal yarn have high conductivity, good tensile properties, high electrothermal efficiency, and stable temperature visualization.

[0005] To address the aforementioned problems, the present invention provides a temperature-visualized electrothermal yarn and its preparation method.

[0006] In a first aspect, the present invention provides a temperature-visualizing yarn, wherein the outer surface of the yarn is provided with a thermochromic ink layer, the interior of the thermochromic ink layer is provided with fibers, and carbon-based conductive composite ink is provided between the fibers.

[0007] Preferably, the fiber is nylon fiber and / or polyester fiber.

[0008] Preferably, the temperature visualization yarn is spiral-shaped.

[0009] A second aspect of the present invention provides a method for preparing a temperature-visible yarn, comprising the following steps:

[0010] Step 1: Place the fibers in deionized water, ketone solvents and / or alcohol solvents for ultrasonic pretreatment, and then dry them;

[0011] Step 2: Add flexible resin and dispersant to carbon-based conductive ink with a carbon content of 2 wt.% to 10 wt.% to obtain carbon-based conductive composite ink;

[0012] Step 3: Immerse the pretreated fibers from Step 1 into the carbon-based conductive composite ink described in Step 2. After removing them, pre-stretch and pre-dry them in the air. Then, wind the conductive coated yarn onto the mandrel and perform heat annealing to set a spiral shape. After removing the mandrel, repeat the immersion and drying process.

[0013] Step 4: Dip the yarn obtained in Step 3 into thermochromic ink, dry and cure it to obtain temperature-visible yarn.

[0014] Preferably, the ketone solvent in step 1 is acetone; the alcohol solvent is ethanol; and the ultrasonic pretreatment time is 10-30 minutes.

[0015] Preferably, the carbon-based conductive ink in step 2 is selected from one or more of carbon nanotube conductive ink, graphene conductive ink, functionalized carbon nanotube ink, and functionalized graphene ink. The functionalized carbon nanotube ink is further preferably carboxylated carbon nanotube conductive ink and / or hydroxylated carbon nanotube conductive ink; the functionalized graphene ink is further preferably carboxylated graphene conductive ink and / or hydroxylated graphene conductive ink.

[0016] Preferably, the dispersant in step 2 is selected from one or more of PVP, sericin and TNWDIS, and the content of the dispersant is selected from 0.1 wt.% to 2 wt.%.

[0017] Preferably, the flexible resin in step 2 is selected from one or more of waterborne acrylic resin, waterborne polyurethane resin, waterborne epoxy resin and silicone-modified acrylic resin, and the content of the flexible resin is 3 wt.%~10 wt.%.

[0018] Preferably, the pre-stretching ratio in step 3 is 5-10%, and the pre-drying time is 10-15 minutes;

[0019] Preferably, the mandrel in step 3 is one or more of PTFE pipe, PVC pipe and PE pipe, with a diameter of 400-800µm, a rotating head speed of 300-500rpm, and a winding density of 1500-2500 rpm;

[0020] Preferably, the heat annealing temperature in step 3 is 150~220℃, and the heat annealing time is 1~3h;

[0021] Preferably, the repeated immersion and drying in step 3 is performed 5 to 8 times, the drying temperature is 60 to 90°C, and the drying time is 10 to 15 minutes.

[0022] Preferably, the thermochromic ink in step 4 is a thermochromic ink with a temperature range of 18–45°C.

[0023] Preferably, the resin matrix in the thermochromic ink in step 4 is selected from one or more of PVC resin, acrylic resin and ABS resin, with a content of 50 wt.% to 80 wt.%, the thermochromic pigment powder content is 5 wt.% to 10 wt.%, the color-changing time is 10 to 15 s, and the fading time is 10 to 20 s;

[0024] Preferably, the drying and curing temperature of the thermochromic ink in step 4 is 60-80°C, and the curing time is 15-30 minutes.

[0025] A third aspect of the present invention provides an application of a temperature-visualizing yarn in the fields of temperature management, smart wearables, and flexible displays.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The method of the present invention is simple to operate, has mild conditions, and allows for controllable yarn diameter and shape, making it suitable for large-scale production.

[0028] 2. The temperature visualization yarn obtained by the present invention has excellent tensile properties and strain electrical stability, enabling the electrothermal yarn to maintain excellent electrothermal stability during the stretching deformation process.

[0029] 3. The temperature-visualizing yarn obtained by this invention can accurately reflect the yarn temperature through color changes during the stretching process, providing a foundation for yarn functionalization and intelligence, and showing great application value in the fields of temperature management, smart wearables and flexible displays. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the spiral structure of the temperature visualization yarn of the present invention;

[0031] Figure 2 This is a schematic diagram of the cross-sectional structure of the temperature visualization yarn of the present invention;

[0032] Figure 3 The time-temperature curves of the temperature-visualized yarn prepared in Example 1 under different voltages;

[0033] Figure 4 The temperature-visible yarn cycling electrothermal performance curve prepared in Example 1;

[0034] Figure 5 The steady-state temperature change curve of the temperature visualization yarn prepared in Example 1 under cyclic stretching is shown.

[0035] Reference numerals: 1. Polyester or nylon fiber; 2. Carbon-based conductive composite ink; 3. Carbon-based nanomaterials; 4. Thermochromic ink. Detailed Implementation

[0036] To make the present invention more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings:

[0037] Example 1

[0038] Step 1: Place the polyester fibers in deionized water, acetone and ethanol respectively for ultrasonic treatment for 10-30 minutes, and then dry them.

[0039] Step 2: Add waterborne polyurethane and dispersant to carbon nanotube conductive ink with a carbon content of 10 wt.%, and sonicate for 1 hour using an ultrasonic cell disruptor to obtain carbon-based conductive composite ink, wherein the content of waterborne polyurethane resin is 5 wt.% and the dispersant is PVP with a content of 0.1 wt.%.

[0040] Step 3: Immerse the polyester fibers treated in Step 1 in the carbon-based conductive composite ink prepared in Step 2 for 5 minutes. After removal, pre-dry them in air under a tension of 10% pre-stretch ratio for 10 minutes. Then, spirally wind them onto a PTFE tube with a diameter of approximately 500µm, rotating the head at 300rpm. Finally, heat-anneal at 100℃ for 3 hours. After removing the PTFE tube, immerse the spiral-shaped electrothermal yarn in the carbon-based conductive composite ink from Step 2 for 5 minutes and dry it at 90℃ for 10 minutes. Repeat this step 5 times.

[0041] Step 4: Immerse the yarn obtained in Step 3 in red thermochromic ink (80 wt.% PVC resin content, 5 wt.% thermochromic pigment content) at 45℃ for 5 minutes, then dry and cure at 60℃ for 30 minutes to obtain a temperature-visible yarn with a diameter of approximately 800 μm and a winding density of 1500 rpm. This temperature-visible yarn appears red below 45℃ and colorless above 45℃.

[0042] Example 2

[0043] Step 1: Place the polyester fibers in deionized water, acetone and ethanol respectively for ultrasonic treatment for 10-30 minutes, and then dry them.

[0044] Step 2: Add waterborne polyurethane and dispersant to carbon nanotube conductive ink with a carbon content of 10 wt.%, and sonicate for 1 hour using an ultrasonic cell disruptor to obtain carbon-based conductive composite ink, wherein the content of waterborne polyurethane resin is 5 wt.% and the dispersant is PVP with a content of 0.1 wt.%.

[0045] Step 3: Immerse the polyester fibers treated in Step 1 in the carbon-based conductive composite ink prepared in Step 2 for 5 minutes. After removal, pre-dry them in air under a tension of 10% pre-stretch ratio for 10 minutes. Then, spirally wind them onto a PTFE tube with a diameter of approximately 500µm, rotating the head at 300rpm, and heat-anneal at 100℃ for 3 hours. After removing the PTFE tube, immerse the spiral-shaped electrothermal yarn in the carbon-based conductive composite ink from Step 2 for 5 minutes, and dry it at 90℃ for 10 minutes. Repeat this step 5 times.

[0046] Step 4: Mix red, blue, and yellow thermochromic inks at a ratio of 1:2:1 to obtain a 45℃ blue / green thermochromic ink (PVC resin content 80 wt.%, thermochromic pigment powder content 5 wt.%). Immerse the stretchable electrothermal yarn obtained in Step 3 in this thermochromic ink for 5 minutes, then dry and cure at 60℃ for 30 minutes to obtain a temperature-visible yarn with a diameter of approximately 800 μm and a winding density of 1500 rpm. This temperature-visible yarn first changes color to purple as the temperature increases, then further to a lighter color, exhibiting more varied color changes, demonstrating the designability of the thermochromic properties of this temperature-visible yarn.

[0047] Example 3

[0048] Step 1: Place the nylon fibers in deionized water, acetone and ethanol respectively for ultrasonic treatment for 10-30 minutes, and then dry them.

[0049] Step 2: Add silicone-modified acrylic resin and dispersant to carbon nanotube conductive ink with a carbon content of 10 wt.%, and sonicate for 1 hour using an ultrasonic cell disruptor to obtain carbon-based conductive composite ink, wherein the content of silicone-modified acrylic resin is 5 wt.%, and the dispersant is silk protein with a content of 1 wt.%.

[0050] Step 3: Immerse the nylon fibers treated in Step 1 in the carbon-based conductive composite ink prepared in Step 2 for 5 minutes. After removal, pre-dry in air for 10 minutes under a tension of 10% pre-stretch ratio. Then, spirally wind the fibers onto a PTFE tube with a diameter of approximately 500µm, rotating the head at 300rpm. Heat anneal at 100℃ for 3 hours. After removing the PTFE tube, immerse the spiral-shaped electrothermal yarn in the carbon-based conductive composite ink from Step 2 for 5 minutes and dry at 90℃ for 10 minutes. Repeat this step 5 times.

[0051] Step 4: Immerse the yarn obtained in Step 3 in 18℃ blue thermochromic ink (PVC resin content 70 wt.%, thermochromic pigment powder content 8 wt.%) for 5 minutes, then dry and cure at 60℃ for 30 minutes to obtain a temperature-visible yarn with a diameter of approximately 800 μm and a winding density of 1500 rpm. This temperature-visible electrothermal yarn is a low-temperature thermochromic yarn, exhibiting blue below 18℃ and colorless above 18℃.

[0052] Comparative Example 1

[0053] Step 1: Place the polyester fibers in deionized water, acetone and ethanol respectively for ultrasonic treatment for 10-30 minutes, and then dry them.

[0054] Step 2: Add water-based acrylic resin and dispersant to carboxylated carbon nanotube conductive ink with a carbon content of 1.8 wt.%, and sonicate for 1 hour using an ultrasonic cell disruptor to obtain carbon-based conductive composite ink, wherein the content of water-based acrylic resin is 5 wt.% and the dispersant is PVP with a content of 0.1 wt.%.

[0055] Step 3: Immerse the polyester fibers treated in Step 1 in the carbon-based conductive composite ink prepared in Step 2 for 5 minutes. After removal, pre-dry in air for 10 minutes under a tension of 10% pre-stretch ratio. Then, spirally wind the fibers onto a PVC tube with a diameter of approximately 300µm, rotating the head at 300rpm. Heat anneal at 100℃ for 3 hours. After removing the PVC tube, immerse the spiral-shaped electric heating yarn in the carbon-based conductive composite ink from Step 2 for 5 minutes and dry at 90℃ for 10 minutes. Repeat this step 5 times.

[0056] Step 4: The yarn obtained in Step 3 is immersed in thermochromic ink (80 wt.% PVC resin content and 5 wt.% thermochromic pigment powder content) at 45°C for 5 minutes, and then dried and cured at 60°C for 30 minutes to obtain a temperature-visible yarn with a diameter of approximately 600 μm and a winding density of 1800 rpm. Because the carbon content in the carbon-based conductive ink is low, the amount of carbon material coated is less, resulting in poorer electrothermal and electrical properties compared to Example 1. This necessitates a higher applied voltage to reach the thermochromic temperature.

[0057] Comparative Example 2

[0058] Step 1: Place the polyester fibers in deionized water, acetone and ethanol respectively for ultrasonic treatment for 10-30 minutes, and then dry them.

[0059] Step 2: Add waterborne epoxy resin and dispersant to carbon nanotube / graphene bicomponent conductive ink with a carbon content of 8 wt.%, and sonicate for 1 hour using an ultrasonic cell disruptor to obtain carbon-based conductive composite ink, wherein the content of waterborne epoxy resin is 1 wt.% and the dispersant is PVP with a content of 0.1 wt.%.

[0060] Step 3: Immerse the polyester fibers treated in Step 1 in the carbon-based conductive composite ink prepared in Step 2 for 5 minutes. After removal, pre-dry them in air for 10 minutes under a tension of 10% pre-stretch ratio. Then, spirally wind them onto a PE tube with a diameter of approximately 500µm, rotating the head at 500rpm. Heat-anneal at 100℃ for 3 hours. After removing the PE tube, immerse the spiral electric heating yarn in the carbon-based conductive composite ink from Step (1) for 5 minutes and dry it at 90℃ for 10 minutes. Repeat this step 5 times.

[0061] Step 4: The yarn obtained in Step 3 is immersed in thermochromic ink (80 wt.% PVC resin content and 5 wt.% thermochromic pigment powder content) at 45°C for 5 minutes, and then dried and cured at 60°C for 30 minutes to obtain a temperature-visible yarn with a diameter of approximately 800 μm and a winding density of 2200 rpm. Because the flexible resin content in the carbon-based conductive ink is only 1 wt.%, the adhesion between the conductive ink and the yarn substrate is poor. After heat annealing on the PE pipe, some of the conductive coating peels off, resulting in poorer electrothermal performance compared to Example 1. Therefore, flexible resin can improve the durability of the electrothermal yarn.

[0062] Comparative Example 3

[0063] Step 1: Place the polyester fibers in deionized water, acetone and ethanol respectively for ultrasonic treatment for 10-30 minutes, and then dry them.

[0064] Step 2: Add waterborne polyurethane and dispersant to carbon nanotube conductive ink with a carbon content of 10 wt.%, and sonicate for 1 hour using an ultrasonic cell disruptor to obtain carbon-based conductive composite ink, wherein the content of waterborne polyurethane resin is 5 wt.% and the dispersant is PVP with a content of 0.1 wt.%.

[0065] Step 3: Immerse the polyester fibers treated in Step 1 in the carbon-based conductive composite ink prepared in Step 2 for 5 minutes. After removing them, pre-dry them directly in air for 10 minutes, and then spirally wind them onto a PTFE tube with a diameter of approximately 500µm. Rotate the head at 300rpm and heat-anneal at 100℃ for 3 hours. After removing the PTFE tube, immerse the spiral electric heating yarn in the carbon-based conductive composite ink from Step (1) for 5 minutes, and dry it at 90℃ for 10 minutes. Repeat this step 5 times.

[0066] Step 4: Immerse the yarn obtained in Step 3 in thermochromic ink (80 wt.% PVC resin content, 5 wt.% thermochromic pigment powder content) at 45℃ for 5 minutes, and then dry and cure at 60℃ for 30 minutes to obtain temperature-visible yarn. Because the yarn was not pre-dried in air under pre-stretch after impregnation with conductive composite ink, a large amount of conductive filler accumulated in the gaps between the yarn fibers, reducing the mechanical properties and uniformity of the electrothermal yarn. After heat annealing on the PTFE tube, the conductive layer cracked, resulting in poorer electrothermal performance than in Example 1 and uneven thermochromic color. Therefore, pre-stretching can uniformize the yarn structure and improve the performance of the electrothermal yarn.

Claims

1. A method for preparing temperature-visible yarn, characterized in that, Includes the following steps: Step 1: Place the fiber in deionized water, ketone solvent and / or alcohol solvent for ultrasonic pretreatment, and then dry it; the fiber is nylon fiber and / or polyester fiber; Step 2: Add flexible resin and dispersant to carbon-based conductive ink with a carbon content of 2wt.% to 10wt.% to obtain carbon-based conductive composite ink; Step 3: Immerse the pretreated fibers from Step 1 into the carbon-based conductive composite ink described in Step 2. After removing them, pre-stretch and pre-dry them in air. Then, wind the conductive coated yarn onto a mandrel and perform heat annealing to set a spiral shape. After removing the mandrel, repeat the immersion and drying process. The heat annealing temperature is 150~220℃, and the heat annealing time is 1~3h. Step 4: Dip the yarn obtained in Step 3 into thermochromic ink, dry and cure it to obtain temperature-visible yarn.

2. The preparation method according to claim 1, characterized in that, Step 1 satisfies one or more of the following conditions: Condition 1 is that the ketone solvent is acetone; Condition 2 is that the alcohol solvent is ethanol; Condition 3 is that the processing time for the ultrasonic pretreatment is 10 to 30 minutes.

3. The preparation method according to claim 1, characterized in that, The carbon-based conductive ink in step 2 is one or more of carbon nanotube conductive ink, graphene conductive ink, functionalized carbon nanotube ink, and functionalized graphene ink.

4. The preparation method according to claim 1, characterized in that, The dispersant in step 2 is one or more of PVP, sericin and TNWDIS, and the content of the dispersant is 0.1 wt.% to 2 wt.%.

5. The preparation method according to claim 1, characterized in that, The flexible resin in step 2 is one or more of waterborne acrylic resin, waterborne polyurethane resin, waterborne epoxy resin, and silicone-modified acrylic resin, and the content of the flexible resin is 3 wt.%~10 wt.%.

6. The preparation method according to claim 1, characterized in that, Step 3 also satisfies one or more of the following conditions: Condition 1 is that the pre-stretching ratio is 5~10% and the pre-drying time is 10~15 min; Condition 2 is that the mandrel is one or more of PTFE pipe, PVC pipe and PE pipe, with a diameter of 400 to 800 µm, a rotating head speed of 300 to 500 rpm, and a winding density of 1500 to 2500 rpm; Condition 3 is that the repeated immersion and drying is performed 5 to 8 times, the drying temperature is 60 to 90°C, and the drying time is 10 to 15 minutes.

7. The preparation method according to claim 1, characterized in that, Step 4 must satisfy one or more of the following conditions: Condition 1 is that the thermochromic ink is a thermochromic ink with a temperature range of 18–45°C; Condition 2 is that the resin matrix in the thermochromic ink is one or more of PVC resin, acrylic resin and ABS resin, with a content of 50 wt.% to 80 wt.%, the thermochromic pigment powder content is 5 wt.% to 10 wt.%, the color change time is 10 to 15 s, and the fading time is 10 to 20 s; Condition 3 is that the drying and curing temperature of the thermochromic ink is 60-80℃ and the curing time is 15-30 min.

8. The preparation method according to claim 3, characterized in that, The functionalized carbon nanotube ink is a carboxylated carbon nanotube conductive ink and / or a hydroxylated carbon nanotube conductive ink; the functionalized graphene ink is a carboxylated graphene conductive ink and / or a hydroxylated graphene conductive ink.

9. A temperature-visualizing yarn prepared by the method for preparing temperature-visualizing yarn according to any one of claims 1-8, characterized in that, The outer surface of the yarn is provided with a thermochromic ink layer, and the interior of the thermochromic ink layer contains fibers, with carbon-based conductive composite ink between the fibers; the fibers are nylon fibers and / or polyester fibers; the yarn is heat-annealed to form a spiral shape; the yarn maintains electrothermal stability during stretching and deformation, and can reflect the yarn temperature through color change during stretching.

10. An application of the temperature visualization yarn as described in claim 9 in the fields of temperature management, smart wearables, and flexible displays.

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