Conductive fabric material and method for producing the same

Abstract

To provide a conductive fabric material enabling improvement in washing durability, physical durability, and biological contact resistance, and a method for producing the same.SOLUTION: A conductive fabric material includes a plurality of conductive fibers composed of a base material with a conductive polymer deposited thereon. A coating film containing a conductive urethane material is provided on at least a part of the conductive polymer. The base material includes at least one selected from polyester, nylon, and urethane. It is preferable that the conductive polymer is poly(3,4-ethylenedioxythiophene) with an iron salt of polystyrenesulfonic acid or p-toluenesulfonic acid added as an oxidant and a dopant.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a conductive cloth material including a plurality of conductive fibers having a conductive polymer attached to a base material, and a method for manufacturing the same.

Background Art

[0002] In recent years, conductive fibers obtained by attaching a conductive polymer such as PEDOT-PSS {poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid)} to a base material made of silk have been known (see, for example, Patent Document 1). Since these conductive fibers have conductivity, hydrophilicity, tensile strength, and water resistance, they can be particularly used as a material for biological electrodes.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, electrodes using conventional conductive fibers have a problem that their conductivity decreases when washing is repeated. In addition, electrodes using conventional conductive fibers are weak against friction and have a problem that they are easily discolored in a wet environment such as sweat. Furthermore, electrodes using conventional conductive fibers have a problem that when measuring an electrocardiogram or the like, it is necessary to wet them with water in order to reduce the contact resistance between the electrode and a person's skin, and the handling is troublesome.

[0005] The present invention has been made based on such problems, and an object thereof is to provide a conductive cloth material capable of improving washing durability, physical durability, and contact resistance with a living body, and a method for manufacturing the same.

Means for Solving the Problems

[0006] The conductive fabric material of the present invention includes conductive fibers with a conductive polymer adhered to a base material, and has a coating film containing a conductive urethane material on at least a part of the conductive polymer.

[0007] The method for manufacturing the conductive fabric material of the present invention includes a step of producing a conductive polymer-attached fabric material containing conductive fibers with a conductive polymer adhered to a base material, and a step of forming a coating film containing a conductive urethane material on the conductive polymer-attached fabric material.

Advantages of the Invention

[0008] According to the conductive fabric material of the present invention, since a coating film containing a conductive urethane material is formed on at least a part of the conductive polymer, the washing durability and physical durability can be improved, and the contact resistance with a living body can be reduced.

[0009] According to the method for manufacturing the conductive fabric material of the present invention, after producing a conductive polymer-attached fabric material containing conductive fibers with a conductive polymer adhered to a base material, a coating film containing a conductive urethane material is formed on the conductive polymer-attached fabric material, so that the conductive fabric material of the present invention can be easily manufactured.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described in detail.

[0012] A conductive cloth material according to an embodiment of the present invention includes conductive fibers to which a conductive polymer is attached on a base material. The shape of the conductive cloth material is in the form of a cloth or a sheet, and may be any of a woven fabric, a knitted fabric, or a non-woven fabric. A non-woven fabric is a sheet-like material in which fibers are intertwined without being woven, and is a material in which fibers are adhered or intertwined by heat, mechanical, or chemical action. This conductive cloth material body can be used, for example, as a conductive polymer electrode.

[0013] The base material is composed of, for example, fibers, and examples of the material include natural fibers such as silk and cotton, and chemical fibers such as synthetic fibers. Among them, it is preferable to include chemical fibers such as synthetic fibers, and for example, it is preferable to include at least one of polyester, nylon, and urethane. This is because it is excellent in productivity and stretchability. In addition, if synthetic fibers having a deformed cross-section (that is, deformed cross-section yarns) are included, the conductive polymer also adheres between the fibers, and it is preferable because the washing resistance can be improved.

[0014] As the conductive polymer, for example, poly(3,4-ethylenedioxythiophene) (hereinafter referred to as PEDOT) added with polystyrene sulfonic acid (hereinafter referred to as PSS) or iron salt of p-toluenesulfonic acid (hereinafter referred to as pTS) as an oxidizing agent and a dopant is preferable. That is, the conductive polymer preferably contains PSS or pTS and PEDOT. In addition, it is preferable to configure the conductive polymer with PEDOT added with pTS because high conductivity can be obtained. pTS functions as an oxidizing agent when polymerizing the monomer of PEDOT, that is, 3,4-ethylenedioxythiophene (hereinafter referred to as EDOT), and also functions as a dopant for expressing conductivity in PEDOT.

[0015] The crystallinity of PEDOT is preferably low, and for example, it is preferable if it is non-crystalline. This is because it can improve the adhesion to the substrate and improve the washing resistance. The crystallinity of PEDOT can be determined by measuring the intensity of a crystalline peak that appears at 2θ=5 degrees to 7 degrees in X-ray diffraction, for example. In addition, the ratio of PEDOT coordinated with pTS among PEDOT is preferably 10% or more and 50% or less. This is because it can further improve the conductivity and washing resistance. The ratio of PEDOT coordinated with pTS among PEDOT can be determined, for example, from the area ratio of the peak of PEDOT obtained by XPS (X-ray Photoelectron Spectroscopy) to the peak of PEDOT coordinated with pTS.

[0016] The conductive polymer is preferably attached to the surface of the substrate in the form of a thin film. This is because high conductivity can be obtained. In addition, the conductive polymer is preferably not only attached to the surface of the substrate, but also permeated into the substrate. FIG. 1 shows an SEM photograph of a cross section of the conductive cloth material according to this embodiment cut in a direction perpendicular to the longitudinal direction of the conductive fibers. In FIG. 1, the white mass-like part is the substrate, and the gray part surrounding it and the gray part present in the substrate in patches are the conductive polymer. If the conductive polymer permeates the substrate in this way, an anchor effect in which the conductive polymer is strongly attached to the substrate can be obtained, which is preferable.

[0017] The penetration ratio of the conductive polymer into the substrate is preferably 1% to 100% in a cross section of the conductive fiber cut in a direction perpendicular to the longitudinal direction, more preferably 10% to 100%, and even more preferably 30% to 100%. This is because a higher anchoring effect can be expected. The penetration ratio of the conductive polymer into the substrate can be obtained, for example, by taking a cross-sectional photograph of the conductive fiber cut in a direction perpendicular to the longitudinal direction and analyzing the image. Specifically, for example, an SEM photograph of a cross section cut in a direction perpendicular to the longitudinal direction of the conductive fiber can be taken, and the penetration ratio can be obtained from the area of the conductive polymer part that has penetrated into the substrate and the area of the entire substrate including the conductive polymer part that has penetrated into the substrate.

[0018] This conductive fabric material also has a coating film containing a conductive urethane material on at least a portion of the conductive polymer. In FIG. 1, the white mass-like portion is the substrate, the gray portion around it is the conductive polymer, and the white thin-film-like portion around it is the coating film. In this way, the coating film is formed in a thin film shape so as to entirely cover the conductive polymer for each conductive fiber. This allows this conductive fabric material to improve washing durability and physical durability, and to reduce contact resistance with a living body.

[0019] The conductive urethane material is a material made by mixing conductive materials such as conductive polymers and carbon with urethane to give it conductivity. Urethane is a compound with urethane bonds formed by the reaction of a polyol component with an isocyanate component, and includes polyurethane. The thickness of the coating film is not particularly limited, but it is preferable that it is thinner than the thickness of the conductive polymer, for example. If the coating film is too thick, the proportion of the conductive polymer is relatively low, resulting in a decrease in conductivity.

[0020] This conductive fabric material can be manufactured, for example, as follows. First, a conductive polymer-attached fabric material containing conductive fibers with a conductive polymer attached to a base material is produced (Step 110; conductive polymer-attached fabric material production step). In the conductive polymer-attached fabric material production step, first, for example, a first liquid containing PSS or pTS and a solvent, and a second liquid containing a monomer of PEDOT and a solvent are mixed to produce a mixed solution (Step 111; mixed solution production step). At this time, it is preferable to adjust the ratio of pTS to the monomer of PEDOT (pTS: monomer of PEDOT) to be within the range of 1:0.2 to 1:0.6 in terms of molar ratio. This is because the proportion of PEDOT in which pTS is coordinated in PEDOT can be within the range of 10% or more and 50% or less.

[0021] Next, a solvent is mixed into the mixed solution to produce a reaction solution (Step 112; reaction solution production step). The solvent in the mixed solution and the reaction solution is preferably water and does not contain alcohols such as ethanol. This is because by using water as the solvent, the polymerization rate of EDOT can be easily slowed down. In addition, it is preferable to adjust the proportion of water in the reaction solution (water / reaction solution) to be within the range of 1 volume% or more and 30 volume% or less.

[0022] Subsequently, the reaction solution is applied to the base material, and EDOT is polymerized to attach the conductive polymer to the base material (Step 113; attachment step). At this time, it is preferable to control the polymerization rate by adjusting at least one of the temperature and humidity during polymerization. By slowing down the polymerization rate, the reaction solution can penetrate into the interior of the base material, and the conductive polymer can penetrate into the interior of the base material. The heating temperature during polymerization is preferably, for example, 20°C to 60°C, the heating time is preferably, for example, 5 minutes to 60 minutes, and the reaction time is preferably 10 minutes to 24 hours. Then, for example, it is washed with water and dried (Step 114; water washing / drying step).

[0023] After the step of manufacturing the conductive polymer-coated fabric material, a coating film containing a conductive urethane material is formed on the conductive polymer-coated fabric material (step 120; coating film forming step). Thereby, a coating film is formed on at least a part of the conductive polymer. The coating film can be formed, for example, by applying a conductive urethane material dissolved in water to the fibers and heating as necessary. The heating temperature is preferably, for example, from 80°C to 140°C. The heating time is preferably, for example, from 5 minutes to 30 minutes.

[0024] Thus, according to the conductive fabric material of the present embodiment, since a coating film containing a conductive urethane material is formed on at least a part of the conductive polymer, the washing durability and physical durability can be improved, and the contact resistance with a living body can be reduced.

[0025] According to the manufacturing method of the present embodiment, after forming a conductive polymer-coated fabric material including conductive fibers to which a conductive polymer is attached on a base material, a coating film containing a conductive urethane material is formed on the conductive polymer-coated fabric material, so that the conductive fabric material of the present invention can be easily manufactured.

Examples

[0026] (Example 1) First, a conductive polymer-coated fabric material including conductive fibers to which a conductive polymer is attached was manufactured on a base material (step 110; conductive polymer-coated fabric material manufacturing step). Specifically, first, a first liquid containing pTS and water as a solvent and a second liquid containing a monomer of PEDOT and water as a solvent were mixed to prepare a mixed solution (step 111; mixed solution preparation step). The ratio of pTS to the monomer of PEDOT (pTS: monomer of PEDOT) was set to be from 1:0.2 to 1:0.6 in terms of molar ratio. Next, water was mixed as a solvent into this mixed solution to prepare a reaction solution (step 112; reaction solution preparation step). The ratio of water in the reaction solution (water / reaction solution) was set to 20% by volume.

[0027] Subsequently, the reaction solution was applied to the substrate, heated, and then maintained in a room at 25°C and 60% humidity for 2 hours to polymerize EDOT, thereby attaching the conductive polymer to the substrate (Step 113; attachment step). A polyester cloth was used as the substrate. The heating temperature was 60°C and the heating time was 6 minutes. Thereafter, it was washed with water and dried (Step 114; washing / drying step). Further, the steps of applying the reaction solution to the substrate, polymerizing it, and washing / drying it were performed in order one more time.

[0028] After performing the process for producing the conductive polymer-attached cloth material, a coating film containing a conductive urethane material was formed on the conductive polymer-attached cloth material (Step 120; coating film formation step). Specifically, the conductive urethane material dissolved in water was applied to the fibers and heated. The heating temperature was 140°C and the heating time was 5 minutes. Thereby, the conductive cloth material of Example 1 was obtained.

[0029] Regarding the obtained conductive cloth material, as described above, SEM photographs of the cross section cut in a direction orthogonal to the longitudinal direction were taken, and the penetration ratio of the conductive polymer into the substrate was determined to be 30%. The SEM photograph of the cross section of the conductive cloth material of Example 1 cut in a direction orthogonal to the longitudinal direction of the conductive fibers is as shown in FIG. 1. Also, in the conductive cloth material of Example 1, it was confirmed that a coating film containing a conductive urethane material was formed on the conductive polymer.

[0030] (Comparative Example 1) As Comparative Example 1 with respect to Example 1, a conductive polymer-attached cloth material was produced in the same manner as in Example 1 except that the coating film formation step was not performed and no coating film was formed. Regarding the obtained conductive polymer-attached cloth material, the penetration ratio of the conductive polymer into the substrate was determined in the same manner as in Example 1, and it was 31.25%. FIG. 2 shows an SEM photograph of the cross section of the conductive polymer-attached cloth material of Comparative Example 1 cut in a direction orthogonal to the longitudinal direction of the conductive fibers. In FIG. 2, the white portion is the substrate, and the gray portion covering the periphery and the gray portion irregularly present inside the substrate are the conductive polymer.

[0031] (Comparative Example 2) As a Comparative Example 2 for Example 1, a first liquid containing pTS and ethanol as a solvent and a second liquid containing EDOT and ethanol as a solvent were mixed to prepare a mixed solution, and a conductive polymer-attached cloth material was produced in the same manner as in Example 1 except that the film-forming step was not performed and the coating film was not formed. Regarding the obtained conductive polymer-attached cloth material, when the penetration rate of the conductive polymer into the base material was determined in the same manner as in Example 1, it was less than 1%. Fig. 3 shows an SEM photograph of a cross section obtained by cutting the conductive polymer-attached cloth material of Comparative Example 2 in a direction orthogonal to the longitudinal direction of the conductive fiber. In Fig. 3, the white portion is the base material, and the gray portion covering the periphery thereof is the conductive polymer. In Fig. 2, the gray portion observed inside the base material is due to the shadow of the base material or the conductive polymer adhering around the base material adhering during cutting.

[0032] (Performance Evaluation 1 of Example 1, Comparative Example 1, and Comparative Example 2) Regarding the conductive cloth material of Example 1 and the conductive polymer-attached cloth materials of Comparative Examples 1 and 2, washing was performed from 1 to 10 times, and the sheet resistance was measured before washing (i.e., 0 times of washing) and after each washing to examine the change in resistance due to washing. The washing method was JIS L 103 method. The sheet resistance was measured using Loresta-AX MCP-T370 manufactured by Mitsubishi Chemical Analytech, and the surface resistance between three points separated by 8 mm was measured. The obtained results are shown in Fig. 4.

[0033] As shown in Fig. 4, according to Example 1 in which a coating film containing a conductive urethane material was formed, the sheet resistance before washing could be made smaller than that of Comparative Examples 1 and 2 in which the coating film was not formed. Further, according to Example 1, the degree to which the sheet resistance increases due to repeated washing could be significantly reduced compared to Comparative Examples 1 and 2. That is, it was found that by forming a coating film containing a conductive urethane material, the sheet resistance and the washing durability can be improved.

[0034] Also, according to Example 1 and Comparative Example 1 where the penetration rate of the conductive polymer into the substrate was 1% or more in the cross-section orthogonal to the longitudinal direction, compared to Comparative Example 2 where it was less than 1%, the sheet resistance before washing was smaller, and the degree to which the sheet resistance increased due to repeated washing was smaller. That is, it was found that by setting the penetration rate of the conductive polymer into the substrate to be 1% or more and 100% or less, further 10% or more and 100% or less, and further 30% or more and 100% or less, the sheet resistance and washing durability can be improved.

[0035] (Performance Evaluation 2 of Example 1, Comparative Example 1, and Comparative Example 2) For the conductive cloth material of Example 1 and the conductive polymer-attached cloth materials of Comparative Examples 1 and 2, the rubbing fastness in a dry environment and a humid environment was measured. The rubbing fastness was measured by the JIS L 0849 Type II test. The obtained results are shown in Table 1.

[0036]

Table 1

[0037] As shown in Table 1, according to Example 1 in which a coating film containing a conductive urethane material was formed, the rubbing fastness could be increased in both the dry environment and the humid environment compared to Comparative Examples 1 and 2 in which no coating film was formed. That is, it was found that by forming a coating film containing a conductive urethane material, the physical durability can be improved and the color bleeding in a wet environment such as with sweat can be suppressed.

[0038] (Performance Evaluation 3 of Example 1, Comparative Example 1, and Comparative Example 2) Using the conductive fabric material of Example 1 and the conductive polymer-coated fabric materials of Comparative Examples 1 and 2, electrodes for measuring electrocardiogram and heart rate were fabricated, and the electrodes were brought into contact with a person to measure the electrocardiogram and heart rate. As a result, in Comparative Example 1 and Comparative Example 2, it was difficult to obtain normal measurements without wetting the electrodes with water, whereas in Example 1, normal measurements could be obtained without wetting the electrodes with water. That is, it was found that by forming a coating film containing a conductive urethane material, the contact resistance between the electrode and human skin could be reduced, and measurements could be performed without wetting with water.

[0039] As described above, the present invention has been described with reference to the embodiments. However, the present invention is not limited to the above embodiments and can be variously modified. For example, in the above embodiments, each component has been specifically described, but not all components need to be provided, and other components may be provided.

Industrial Applicability

[0040] In recent years, in Japan, with the progress of aging, for the purpose of monitoring health status and extending healthy life expectancy, wearable devices have been developed to detect biological information such as electrocardiogram (information underlying electrocardiogram; the same shall apply hereinafter) and electromyogram by unobtrusive sensing, prevent diseases and injuries, and detect diseases at an early stage. However, when measuring electrocardiogram or the like, conventionally, it has been necessary to attach a gel or a sticky seal for measurement, or strongly press with a belt, making it difficult to wear for a long time. In addition, although disposable seals or the like are used as a substitute, there may be a sense of discomfort during wearing, and problems such as rough skin may occur. Conventionally, those mainly coated with Ag metal have also been generally used, but there are concerns about adverse effects on the living body. Furthermore, there has been a problem that the electrodes are oxidized by moisture and sweat, resulting in performance degradation. That is, it is desired that the electrodes do not have an adverse effect on the living body even when used continuously for a long time. According to the present invention, for example, a mixed solution containing a monomer of a conductive polymer, an oxidizing agent, and ethanol as a solvent is applied to the surface of commercially available underwear and polymerized by a chemical reaction, so that the underwear can be provided with a conductive function. The electrode can be measured without strongly pressing against the living body, the underwear can be manufactured at a lower cost than conventional products, and biological information can be detected. If the price of the wear becomes low, it can be widely applied to healthcare and nursing support robots, work support robots, fitness, work clothes, etc.

Claims

1. A conductive fabric material comprising conductive fibers with a conductive polymer attached to a substrate, having a coating film containing a conductive urethane material on at least a part of the conductive polymer. The conductive fabric material is characterized by this.

2. The substrate contains at least one of polyester, nylon, and urethane, and the conductive fabric material according to Claim 1 is characterized by this.

3. The conductive polymer is poly(3,4-ethylenedioxythiophene) with polystyrene sulfonic acid or an iron salt of p-toluenesulfonic acid added as an oxidizing agent and a dopant. The conductive fabric material according to Claim 1 is characterized by this.

4. The conductive polymer also penetrates into the interior of the substrate, and the penetration ratio of the conductive polymer into the substrate is 1% or more and 100% or less in a cross-section perpendicular to the longitudinal direction. The conductive fabric material according to Claim 1 is characterized by this.

5. A fabric material manufacturing process for manufacturing a conductive polymer-attached fabric material containing conductive fibers with a conductive polymer attached to a substrate, and a coating film forming process for forming a coating film containing a conductive urethane material on the conductive polymer-attached fabric material. The manufacturing method of the conductive fabric material is characterized by including these.

6. In the process of manufacturing the conductive polymer-attached fabric material, the conductive polymer is polymerized using a reaction solution containing polystyrene sulfonic acid or an iron salt of p-toluenesulfonic acid, a monomer of poly(3,4-ethylenedioxythiophene), and a solvent. The solvent is water, and the polymerization rate is controlled by adjusting at least one of the temperature and humidity during polymerization, so that the conductive polymer penetrates into the interior of the substrate. The manufacturing method of the conductive fabric material according to Claim 5 is characterized by this.

Images