Patent Application
20240279870
This application claims priority to Taiwanese Invention patent Application No. 112106338, filed on Feb. 21, 2023.
The disclosure relates to a method for preparing a fiber, and more particularly to a method for preparing an elastic conductive fiber.
US 20160122941 A1 discloses a conductive yarn, a conductive yarn-based pressure sensor including the conductive yarn, and a method for producing the conductive yarn. In this patent document, the conductive yarn includes a fiber, a flexible polymer on the fiber, and metallic nanoparticles contained in the flexible polymer. The a method for producing the conductive yarn includes: coating a yarn with a flexible polymer by, for example, immersing the yarn in a flexible polymer solution; soaking the flexible polymer coated on the yarn in a metallic precursor solution to allow metallic ions to be absorbed into the flexible polymer; and reducing the metallic ions to metallic nanoparticles with a reducer. By coating the flexible polymer on a surface of the yarn and forming the metallic nanoparticles in the flexible polymer, the subsequently formed conductive yarn, which has both flexibility and conductivity, can therefore be obtained without changing the properties of the yarn itself.
In spite of the aforesaid, there is still a need for those skilled in the art to develop a conductive yarn having a conductivity that meets the requirements of the industry.
Therefore, an object of the disclosure is to provide a method for preparing an elastic conductive fiber that can alleviate at least one of the drawbacks of the prior art. The method includes:
Before the present disclosure is described in greater detail, it should be noted that if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Taiwan or any other country.
For the purpose of this specification, it will be clearly understood that the word “comprising” means “including but not limited to”, and that the word “comprises” has a corresponding meaning.
Unless otherwise defined, all technical and scientific terms used herein have the meaning commonly understood by a person skilled in the art to which the present disclosure belongs. One skilled in the art will recognize many methods and materials similar or equivalent to those described herein, which could be used in the practice of the present disclosure. Indeed, the present disclosure is in no way limited to the methods and materials described.
The present disclosure provides a method for preparing an elastic conductive fiber, which includes:
According to the present disclosure, the alkaline solution is used to generate a plurality of hydroxyl groups on a surface of the elastic polyurethane fiber so that dipole-dipole interactions may occur between the hydroxyl groups and trifluoroacetate ions in the metal trifluoroacetate, thereby enhancing the absorption of the metal trifluoroacetate by the alkaline-treated elastic polyurethane fiber. Hence, an amount of the metal ions in the processed elastic polyurethane fiber is increased, thereby elevating the electrical conductivity of the elastic polyurethane fiber. In certain embodiments, the alkaline solution may contain a solvent. Examples of the solvent may include, but are not limited to, water, methanol, ethanol, and dimethyl sulfoxide (DMSO). In certain embodiments, the base may be present in an amount greater than or equal to 20 wt % and less than 30 wt % based on 100 wt % of the alkaline solution. In certain embodiments, the base may be present in an amount ranging from 24 wt % to 26 wt % based on 100 wt % of the alkaline solution. In certain embodiments, the elastic polyurethane fiber may be immersed in the alkaline solution having a temperature ranging from 25° C. to 90° C. for a time period ranging from 10 minutes to 120 minutes.
According to the present disclosure, the metal trifluoroacetates may be of a single type or different types. Examples of the metal trifluoroacetate may include, but are not limited to, silver trifluoroacetate, copper trifluoroacetate, and gold trifluoroacetate. In certain embodiments, the metal trifluoroacetate may be selected from the group consisting of silver trifluoroacetate, copper trifluoroacetate, gold trifluoroacetate, and combinations thereof.
In certain embodiments, the metal trifluoroacetate may be present in an amount ranging from 10 wt % to 50 wt % based on 100 wt % of the first treating composition.
According to the present disclosure, the alcohol solvent may be utilized to dissolve the metal trifluoroacetate, and may be of a single type or different types. Examples of the alcohol solvent may include, but are not limited to, an alcohol having one carbon atom, an alcohol having two carbon atoms, an alcohol having three carbon atoms and an alcohol having four carbon atoms. In certain embodiments, the alcohol solvent may be selected from the group consisting of an alcohol having one carbon atom, an alcohol having two carbon atoms, an alcohol having three carbon atoms and an alcohol having four carbon atoms.
In certain embodiments, the alkaline-treated elastic polyurethane fiber may be immersed in the first treating composition having a temperature ranging from 25° C. to 70° C. for a time period ranging from 5 minutes to 40 minutes.
Examples of the reducing agent of the second treating composition may include, but are not limited to, aniline, ascorbic acid and hydrazine. In certain embodiments, the reducing agent may be present in an amount ranging from 0.5 wt % to 4 wt % based on 100 wt % of the second treating composition.
In certain embodiments, the processed elastic polyurethane fiber may be immersed in the second treating composition having a temperature ranging from 25° C. to 90° C. for a time period ranging from 10 minutes to 140 minutes.
In certain embodiments, the second treating composition may further contain a nano conductive material. Examples of the nano conductive material of the second treating composition may include, but are not limited to, a nano metal wire, a nano metal particle, and a carbon nanotube. In addition, examples of the nano metal wire may include, but are not limited to, a nano silver wire, a nano gold wire, and a nano copper wire. Examples of the nano metal particle may include, but are not limited to, a nano silver particle, a nano gold particle, and a nano copper particle.
In certain embodiments, the nano conductive material may be present in an amount ranging from 1.56 wt % to 50 wt % based on 100 wt % of the second treating composition.
According to the present disclosure, the thus obtained elastic conductive fiber may be further immersed in the first treating composition and the second treating composition in sequence as described above. The immersion of the elastic conductive fiber in the first treating composition, and then in the second treating composition may be repeated several times, so as to enhance the electrical conductivity of the elastic conductive fiber.
The disclosure will be further described by way of the following examples. However, it should be understood that the following examples are solely intended for the purpose of illustration and should not be construed as limiting the disclosure in practice.
First, 10 g of elastic polyurethane fiber (5 cm in length and 0.5 mm in diameter) was immersed in 10 mL of an alkaline solution at a temperature of 25° C. for 30 minutes, so as to obtain an alkaline-treated elastic polyurethane fiber. The alkaline solution contained triethylamine and water, and the triethylamine was present in an amount of 25 wt % based on 100 wt % of the alkaline solution.
Afterward, 10 g of the alkaline-treated elastic polyurethane fiber was immersed in 10 ml of a first treating composition at a temperature of 25° C. for 30 minutes, so that the alkaline-treated elastic polyurethane fiber absorbed the first treating composition to from an immersed elastic polyurethane fiber. The first treating composition contained silver trifluoroacetate and ethanol, and the silver trifluoroacetate was present in an amount of 35 wt % based on 100 wt % of the first treating composition. Subsequently, the immersed elastic polyurethane fiber was taken out from the first treating composition, and then was dried in an oven at 50° C. for 30 minutes, so as to remove the ethanol remaining in the immersed elastic polyurethane fiber, thereby obtaining a processed elastic polyurethane fiber containing the silver trifluoroacetate.
Next, the processed elastic polyurethane fiber was immersed in 10 mL of a second treating composition at a temperature of 25° C. for 60 minutes, thereby obtaining an elastic conductive fiber. The second treating composition contained ascorbic acid and 10 ml of water. In addition, the ascorbic acid was present in an amount of 2 wt % based on 100 wt % of the second treating composition. In formation of the elastic conductive fiber, the ascorbic acid was utilized to reduce silver ions in the silver trifluoroacetate of the processed elastic polyurethane fiber so that silver particles were formed on a surface of the processed elastic polyurethane fiber. The thus obtained elastic conductive fiber was then taken out from the second treating composition, followed by washing off the ascorbic acid remaining therein using 63 mL of deionized water and subsequently drying in an oven at 50° C. for 30 minutes.
The procedures for preparing the elastic conductive fiber of Example 2 were similar to those of Example 1, except that sodium hydroxide was used in replacement of the triethylamine.
First, 10 g of elastic polyurethane fiber (5 cm in length and 0.5 mm in diameter) was immersed in 10 mL of an alkaline solution at a temperature of 25° C. for 30 minutes, so as to obtain an alkaline-treated elastic polyurethane fiber. The alkaline solution contained sodium hydroxide and water, and the sodium hydroxide was present in an amount of 25 wt % based on 100 wt % of the alkaline solution.
Afterward, 10 g of the alkaline-treated elastic polyurethane fiber was immersed in 10 ml of a first treating composition at a temperature of 25° C. for 30 minutes so that the alkaline-treated elastic polyurethane fiber absorbed the first treating composition to form an immersed elastic polyurethane fiber. The first treating composition contained silver trifluoroacetate and ethanol, and the silver trifluoroacetate was present in an amount of 35 wt % based on 100 wt % of the first treating composition. Subsequently, the immersed elastic polyurethane fiber was taken out from the first treating composition, and then was dried in an oven at 50° C. for 30 minutes, so as to remove the ethanol remaining in the immersed elastic polyurethane fiber, thereby obtaining a processed elastic polyurethane fiber containing the silver trifluoroacetate.
Next, the processed elastic polyurethane fiber was immersed in 10 mL of a second treating composition at a temperature of 25° C. for 60 minutes, thereby obtaining an elastic conductive fiber. The second treating composition contained nano silver wires (with lengths ranging from 10 μm to 20 μm and diameters ranging from 5 nm to 20 nm), ascorbic acid and 10 ml of water. In addition, the nano silver wires were present in an amount of 25 wt % based on 100 wt % of the second treating composition, and the ascorbic acid was present in an amount of 2 wt % based on 100 wt % of the second treating composition. In formation of the elastic conductive fiber, the ascorbic acid was utilized to reduce silver ions in the silver trifluoroacetate of the processed elastic polyurethane fiber so that silver particles were formed on a surface of the processed elastic polyurethane fiber. In the meanwhile, the nano silver wires were deposited on a surface of the processed elastic polyurethane fiber and on a surface of at least one of the silver particles. The thus obtained elastic conductive fiber was then taken out from the second treating composition, followed by washing off the ascorbic acid remaining therein using 63 mL of deionized water and subsequently drying in an oven at 50° C. for 30 minutes.
First, 10 g of elastic polyurethane fiber (5 cm in length and 0.5 mm in diameter) was immersed in 10 mL of a first treating composition at a temperature of 25° C. for 30 minutes, so that the elastic polyurethane fiber absorbed the first treating composition to from an immersed elastic polyurethane fiber. The first treating composition contained silver trifluoroacetate and ethanol, and the silver trifluoroacetate was present in an amount of 35 wt % based on 100 wt % of the first treating composition. Afterward, the immersed elastic polyurethane fiber was taken out from the first treating composition, and then was dried in an oven at 50° C. for 30 minutes, so as to remove the ethanol remaining in the immersed elastic polyurethane fiber, thereby obtaining a processed elastic polyurethane fiber containing the silver trifluoroacetate.
Next, the processed elastic polyurethane fiber was immersed in 10 mL of a second treating composition at a temperature of 25° C. for 60 minutes, thereby obtaining an elastic conductive fiber. The second treating composition contained ascorbic acid and 10 mL of water. In addition, the ascorbic acid was present in an amount of 2 wt % based on 100 wt % of the second treating composition. In formation of the elastic conductive fiber, the ascorbic acid was utilized to reduce silver ions in the silver trifluoroacetate of the processed elastic polyurethane fiber so that silver particles were formed on a surface of the processed elastic polyurethane fiber. The thus obtained elastic conductive fiber was then taken out from the second treating composition, followed by washing off the ascorbic acid remaining therein using 63 mL of deionized water, and subsequently drying in an oven at 50° C. for 30 minutes.
The procedures for preparing the elastic conductive fiber of Comparative Example 2 were similar to those of Example 1, except that acetic acid was used in replacement of the triethylamine.
First, 10 g of elastic polyurethane fiber (5 cm in length and 0.5 mm in diameter) was immersed in 10 mL of a first treating composition at a temperature of 25° C. for 30 minutes, so that the elastic polyurethane fiber absorbed the first treating composition to from an immersed elastic polyurethane fiber. The first treating composition contained silver trifluoroacetate and ethanol, and the silver trifluoroacetate was present in an amount of 35 wt % based on 100 wt % of the first treating composition. Afterward, the immersed elastic polyurethane fiber was taken out from the first treating composition, and then was dried in an oven at 50° C. for 30 minutes, so as to remove the ethanol remaining in the immersed elastic polyurethane fiber, thereby obtaining a processed elastic polyurethane fiber containing the silver trifluoroacetate.
Next, the processed elastic polyurethane fiber was immersed in 10 mL of a second treating composition at a temperature of 25° C. for 60 minutes, thereby obtaining an elastic conductive fiber. The second treating composition contained nano silver wires (with lengths ranging from 10 μm to 20 μm and diameters ranging from 5 nm to 20 nm), ascorbic acid and 10 ml of water. In addition, the nano silver wires were present in an amount of 25 wt % based on 100 wt % of the second treating composition, and the ascorbic acid was present in an amount of 2 wt % based on 100 wt % of the second treating composition. In formation of the elastic conductive fiber, the ascorbic acid was utilized to reduce silver ions in the silver trifluoroacetate of the processed elastic polyurethane fiber, so that silver particles were formed on a surface of the processed elastic polyurethane fiber. In the meanwhile, the nano silver wires were deposited on a surface of the processed elastic polyurethane fiber and on a surface of at least one of the silver particles. The thus obtained elastic conductive fiber was then taken out from the second treating composition, followed by washing off the ascorbic acid remaining therein using 63 mL of deionized water, and subsequently drying in an oven at 50° C. for 30 minutes.
The procedures for preparing the elastic conductive fiber of each of Comparative Examples 4 and 5 were similar to those of Example 1, except that anomia and potassium hydroxide were used respectively in replacement of the triethylamine.
Each of the elastic polyurethane fiber and the elastic conductive fibers obtained in Examples 2 and 3 as well as in Comparative Example 1 was subjected to weight measurement using a balance. Afterward, the density of silver (mg/cm3) of a respective one of the aforesaid fibers was calculated using the following Equation (I):
A respective one of the elastic conductive fibers of Examples 1 to 3 (each having a length of 3 cm) was placed on a tensile machine (WINTEAM; Model: WTSPP-20200-A) for being stretched to 4.5 cm for numerous times. In addition, the resistance values at the 1st time of stretching, the 1000th time of stretching, the 2000th time of stretching, and the 3000th time of stretching were respectively measured using a resistance measuring instrument (Keithley; Model: LSR4-KHT200), which was electrically connected to the tensile machine, and a data processor with Keith Link software.
A respective one of the elastic conductive fibers of Examples 1 to 3 and Comparative Example 1, and the elastic polyurethane fiber (each having a length of 3 cm) was subjected to electrical resistance (A0) measurement using a resistance measuring instrument (Keithley, Model: LSR4-KHT200), and then was placed in a tensile machine (WINTEAM; Model: WTSPP-20200-A) for being stretched to 3.9 cm with a predetermined tensile force. Next, the tensile force was released so that the respective one of the elastic conductive fiber and the elastic polyurethane fiber returned to its original length. Thereafter, the respective one of the elastic conductive fiber and the elastic polyurethane fiber was subjected to electrical resistance (A1) measurement using the aforesaid resistance measuring instrument. The resistance value (A0) and resistance value (A1) measured for the elastic polyurethane fiber are both 107 (2/cm, and the resistance value (A0) and resistance value (A1) measured for the respective one of the elastic conductive fiber ae shown in Table 3 below.
A respective one of the elastic conductive fibers of Examples 2 and 3 as well as in Comparative Example 1 (each having a length of 3 cm) was subjected to electrical resistance (A0) measurement using a resistance measuring instrument (Keithley, Model: LSR4-KHT200), and then was placed on a tensile machine (WINTEAM, Model: WTSPP-20200-A) for being stretched to 3.9 cm, 4.2 cm and 4.5 cm, respectively, with different tensile forces. In the meanwhile, the resistance value at each length was measured using the resistance measuring instrument, which was electrically connected to the tensile machine, and a data processor with Keith Link software.
Afterward, the change rate of electrical resistance at each length was calculated using the following Equation (II):
The results are shown in Tables 3 below.
A respective one of a surface area and a cross-sectional area of the elastic conductive fibers of Example 2 and Comparative Example 1 was photographed using a scanning electron microscope, and then subjected to an energy-dispersive X-ray spectroscopy (JEOL; Model: JSM-6701F) such that X-rays are irradiated on the surface area and the cross-sectional area, so as to obtain an energy dispersive X-ray spectrum showing a peak of silver signal.
Afterward, the silver content was calculated using the following Equation (III):
The results are shown in Tables 3 below.
Referring to Table 3, by using the sodium hydroxide (serving as the base) contained in the alkaline solution to treat the elastic polyurethane fiber of Example 2, the thus obtained elastic conductive fiber of Example 2 had a resistance value (A0) of 8.67 Ω/cm in. On the contrary, the elastic polyurethane fiber of Comparative Example 1 was not treated with the alkaline solution, therefore, the thus obtained elastic conductive fiber of Comparative Example 1 had a resistance value (A0) of 20.08 Ω/cm. These results indicate that in the method for preparing the elastic conductive fiber of the present disclosure, by virtue of the treatment of the elastic polyurethane fiber with a base (i.e., triethylamine and sodium hydroxide), the elastic conductive fiber thus obtained has a high electrical conductivity.
Additionally, in the method for preparing the elastic conductive fiber of the present disclosure, by using the alkaline solution to treat the elastic polyurethane fiber, and adding the nano silver wires into the second treating composition, the thus obtained elastic conductive fiber of Example 3 had a resistance value (A0) of 5.40 Ω/cm. In view of the above description, the elastic conductive fiber obtained in Example 3 had a resistance value even lower than that of the elastic conductive fiber of Example 2. Moreover, each of the elastic conductive fibers obtained in Examples 2 and 3 had the resistance value (A0) similar to the resistance value (A1), i.e., the resistance value measured after release of the tensile force. These results indicate that by virtue of the method of the present disclosure, the thus obtained elastic conductive fiber is reusable, and hence has a long service life.
Furthermore, referring to Table 3, each of the elastic conductive fibers obtained in Examples 2 and 3 had resistance values varying with lengths thereof. These results indicate that by virtue of the method of the present disclosure, the thus obtained elastic conductive fiber can serve as a strain-sensing fiber, e.g., a resistance strain-sensing fiber, and hence can be applied in a strain sensor used in a wearable electronic device, so that the stain sensor is conferred with various advantages, such as a low initial resistance, a broad strain-sensing range, and a good quality of electrical resilience under repeated stretching.
In sum, through treating the elastic polyurethane fiber with an alkaline solution, i.e., the alkaline solution containing triethylamine or sodium hydroxide, the method for preparing the elastic conductive fiber according to the present disclosure can fabricate the elastic conductive fiber having good electrical conductivity.
In the description above, for the purposes of explanation, numerous specific details have been set forth in order to provide a thorough understanding of the embodiment(s). It will be apparent, however, to one skilled in the art, that one or more other embodiments may be practiced without some of these specific details. It should also be appreciated that reference throughout this specification to “one embodiment,” “an embodiment,” an embodiment with an indication of an ordinal number and so forth means that a particular feature, structure, or characteristic may be included in the practice of the disclosure. It should be further appreciated that in the description, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of various inventive aspects; such does not mean that every one of these features needs to be practiced with the presence of all the other features. In other words, in any described embodiment, when implementation of one or more features or specific details does not affect implementation of another one or more features or specific details, said one or more features may be singled out and practiced alone without said another one or more features or specific details. It should be further noted that one or more features or specific details from one embodiment may be practiced together with one or more features or specific details from another embodiment, where appropriate, in the practice of the disclosure.
While the disclosure has been described in connection with what is(are) considered the exemplary embodiment(s), it is understood that this disclosure is not limited to the disclosed embodiment(s) but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.
| Number | Date | Country | Kind |
|---|---|---|---|
| 112106338 | Feb 2023 | TW | national |
