JPH06339469A - Electrode material - Google Patents

Abstract

PURPOSE:To provide an electrode material which has excellent dimensional stability in addition to excellent conductivity and uniform surface resistance, provides good touch, and also provides rigidity, proper flexibility and flexural strength simultaneously. CONSTITUTION:An electrode material contains ceramic fibers and/or carbon fibers by 1 to 50wt.%, with the rest being a thermoplastic resin, the ceramic fibers having an average diameter of 0.01 to 3.0mum, an average length of 1 to 500mum, an average aspect ratio of 5 to 500, and a resistivity of 10<-3> to 10<4>OMEGA.cm, the carbon fibers having an average diameter of 0.5 to 3.0mum, an average length of 0.5 to 20mm, an average aspect ratio of 200 to 10000, and a resistivity of 10<-3> to 10<4>OMEGA.cm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode material and an electrode molded article obtained by molding the material.

[0002]

2. Description of the Related Art An electrode used for an object having an oily surface such as a living body, such as an electrode for measuring an electrocardiogram, is required to have compatibility with the oily surface, adhesiveness, deformation due to water, and the like. Conventionally, as an electrode material used for such a purpose, a water-soluble or hydrophilic polymer containing an electrolyte or a polyelectrolyte is known, and these are all used in a hydrogel state. . However,
These electrode materials have the drawback that the original shape cannot be easily deformed due to swelling or dissolution with water, which poses a problem during storage and transportation.For example, they can be attached to a toilet seat and used as an electrode for measuring electrocardiogram. When used, the durability was insufficient.

As an electrode material for improving such drawbacks,
For example, a conductive composition in which carbon black particles, which are a conductive substance, are dispersed in a rubber component has been proposed (JP-A-63-131406). Such a conductive composition is intended to improve the affinity and adhesiveness to an oily surface such as a human body by using rubber as a matrix, and to prevent deformation due to moisture or the like.
However, the electrically conductive composition has a drawback that the electrical conductivity does not reach a desired range because the electrical contact resistance to the skin is high.

It is also conceivable to disperse or emulsify an electrolyte with water in a continuous layer of rubber or the like to obtain a conductive composition, but such a method also fails to obtain sufficient conductivity. Moreover, there is a problem that water easily bleeds out of the system.

In addition, none of the above-mentioned conventional electrode materials can not be freely designed as a product, and are insufficient in strength.

On the other hand, it is known that when a thermoplastic resin composition containing conductive fibers is injection-molded, a surface skin layer having a relatively low filling ratio of conductive fibers and a thickness of about 300 to 400 μm is formed on the surface of the molded product. ing. The cause of the surface skin layer is that the molten thermoplastic resin exhibits a high viscosity, a fountain flows when flowing in the mold, causing so-called fountain flow, and the injected resin is instantaneously on the mold wall surface. It is believed that this is because the heat is taken away by and solidifies. Since the surface skin layer has a relatively low filling rate of conductive fibers, when the thickness exceeds about 200 μm, the surface electric resistance value becomes significantly higher than the desired range, and the resistance value also varies, If a molded product having such a surface skin layer is used as, for example, an electrode for measuring an electrocardiogram, accurate measured values cannot be obtained.

[0007]

Means for Solving the Problems The inventors of the present invention have made diligent research efforts to solve the problems that cannot be solved by the conventional techniques as described above, and as a result, the conductivity and the uniformity required by consumers are obtained. We have succeeded in obtaining an electrode material having not only surface resistance but also excellent dimensional stability, good feel to the touch, and rigidity, moderate flexibility and bending strength, and have completed the present invention.

That is, according to the present invention, the average diameter is 0.01 to 3.
0 μm, average length 1 to 500 μm, average aspect ratio 5 to 500 μm, specific resistance of ceramic fiber of 10 ^{−3 to} 10 ⁴ Ω · cm and / or average diameter of 0.5 to 3.0.
μm, average length 0.5 to 20 mm, average aspect ratio 200 to 10000, specific resistance 10 ^{−3 to} 10 ⁴ Ω · c
The present invention relates to an electrode material containing 1 to 50% by weight of carbon fiber of m and the balance being a thermoplastic resin, and an electrode molded article obtained by molding the material.

In the present invention, it is indispensable to use a minute fibrous substance to which conductivity is imparted, that is, a thermoplastic resin containing a ceramic fiber and / or a carbon fiber, when producing a material for an electrode.

Examples of the ceramic fiber used in the present invention include alkali titanate fiber, alkaline earth titanate fiber, aluminum titanate fiber, titania fiber, aluminum borate fiber, magnesium borate fiber, alumina fiber, and silicic acid. Examples of the compound include metal oxide compounds such as fibers and silicon nitride fibers and metal nitride compounds that are single crystals or polycrystals, but the present invention is not limited thereto. The ceramic fiber may have conductivity by depositing or depositing metal, metal oxide, carbon, or the like on the fiber surface. Metal on the fiber surface,
For attaching or depositing metal oxides, carbon, etc., for example, a method of reducing and firing the fibers in a reducing gas atmosphere, C
Well-known methods such as the VD method (chemical vapor deposition method), the electroless plating method, the dipping method, and the spray coating method can be widely applied.

In the present invention, carbon fibers produced by a known method, for example, the method described in JP-A-4-185720 can be widely used.

The ceramic fiber and carbon fiber used in the present invention must have a specific resistance of 10 ^{−3 to} 10 ⁴ Ω · cm. The ceramic fiber has an average diameter of 0.01 to 3.0 μm, an average length of 1 to 500 μm, and an average aspect ratio of 5 to 500. The carbon fiber has an average diameter of 0.5 to 3.0 μm. Average length is 0.5-2
It is necessary that the thickness is 0 mm and the average aspect ratio is 200 to 10,000. Here, the average diameter means an equivalent diameter when the fiber is not circular.

In the present invention, the use of fibers of this size is important for thinning the surface skin layer described later. In addition, the electrode material produced by using the fiber of this size has excellent surface smoothness and has a preferable tactile sensation as an electrode for human body. Further, since the tip of the molded product is reinforced with fibers, even if it is used in applications where a strong load is applied to the details of the product, there is little deformation or damage. The use of fibers larger than the above is unsuitable because it tends to cause local unevenness of the surface resistance on the surface.

The compounding amount of the ceramic fiber and / or carbon fiber in the electrode material of the present invention is usually 1 to 50% by weight, preferably 3 to 40% by weight, particularly preferably 5 to 30% by weight. If the blending amount is less than 1% by weight, the effect of adding the resin becomes poor. On the contrary, if the blending amount exceeds 50% by weight, the properties of the thermoplastic resin described below are impaired, so that the properties of the electrode material cannot be adjusted. It will be difficult.

In the present invention, these fibers may be subjected to various known surface treatments in order to enhance the interfacial adhesion between the ceramic resin or carbon fiber and the thermoplastic resin and enhance the mixing / dispersing property. For example, the surface treatment may be performed using a surface treatment agent such as a silane-based or titanate-based coupling agent.

As the thermoplastic resin used in the present invention, conventionally known ones can be widely used. For example, nylon 6, nylon 66, nylon 12, nylon 6-10,
Polyamide resin such as nylon 11 or nylon 6-12,
Polyester resin such as aromatic polyamide resin, polyacetal resin, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polycarbonate resin, polypropylene resin, acrylonitrile-butadiene-styrene resin (ABS resin), polyethylene resin, silicone resin, polyester elastomer Resin, polyurethane resin, etc. may be mentioned. Moreover, what foamed the thermoplastic composition can also be used as the thermoplastic resin of this invention.

The electrode material of the present invention includes stabilizers, antioxidants, lubricants, metal powders, carbon black, carbon fibers of ordinary thickness, and for improving the releasability from the mold during molding. Various known compounding agents such as the above-mentioned additives can be appropriately mixed.

When the electrode material according to the present invention is molded into a desired shape, it is preferable to use an injection molding method.
Other known molding methods can be used to produce the desired product.

When the electrode material is molded by the injection molding method, the surface skin layer of the obtained electrode molded material is 20
The thickness is preferably 0 μm or less, and more preferably 100 μm or less. If the surface skin layer is 200 μm or more, the volume resistance value and the surface resistance value of the molded product may partially differ, and the surface resistance value becomes high. Is not preferable.

The inventors of the present invention used a ceramic fiber or carbon fiber compounding ratio to the resin to form the surface skin layer,
Injection pressure, injection temperature, molding (material) temperature during injection molding,
Conditions such as injection speed and mold temperature are related, and the thickness of the skin layer can be 200 μm by adjusting these conditions appropriately.
It has been found that the following moldings can be obtained.

These conditions differ depending on the thermoplastic resin used, but the injection pressure should be higher than usual and the injection amount should be lower than usual. The mold temperature is preferably higher than usual. Table 1 shows preferable conditions for main resins by an FS150 injection molding machine manufactured by Nissei Plastic Industry Co., Ltd.

[0022]

[Table 1]

The molded product obtained by molding the electrode material of the present invention can be used as various measuring electrodes. For example, it can be attached to a toilet seat and used as an electrocardiogram measurement electrode. At this time, the molded article may be attached to at least one portion of the toilet seat that can come into contact with the skin. A specific installation example is shown in FIG.

Further, since the molded product obtained by molding the electrode material of the present invention has an excellent surface resistance value and is uniform, a resistance proportional to the contact area can be obtained when a conductive substance is contacted. have. Further, since any portion shows a uniform resistance value, it has a feature that a resistance value proportional to the contact length can be obtained. Therefore, it can be suitably used as a material for an electrode for a depth measuring device, a position measuring sensor, or the like.

[0025]

EFFECTS OF THE INVENTION A molded article for an electrode manufactured by using the electrode material of the present invention has the following preferable features.

1. It has a low electric resistance value, and there is no problem in measuring minute currents.

2. The electric resistance value of the molded product is uniform over the entire part of the molded product, and the electric resistance value is so low that the difference in the measured values due to the difference in the contact position with the measurement object is hardly a problem.

3. The molded product is hardly subject to deformation due to use or deterioration due to oxidation over a long period of time.

4. The surface is smooth and feels good.

5. It has both rigidity, moderate flexibility and bending strength.

The electrode molded article of the present invention has almost no change in surface resistance value and volume resistance value, and is capable of sensing a minute voltage from the human body. Therefore, the toilet seat to which the molded article for an electrode of the present invention is attached has a function of enabling health management at home when facing an aging society in the future, and can be said to be effective from a social perspective. Since the electrode material of the present invention is based on a thermoplastic resin, it has the characteristic that it can be washed with water, and therefore can be used in many applications.

[0032]

EXAMPLES The present invention will be further clarified with reference to Examples and Comparative Examples below.

Example 1 Conductive potassium titanate fibers obtained by reducing and firing potassium titanate fibers at 1000 ° C. in an inert atmosphere (fiber diameter 0.3 μm, fiber length 15 μm, specific resistance 10 ⁻² Ω · cm,
Aromatic polyamide resin (nylon MXD) manufactured by melting Otsuka Chemical Co., Ltd. at the compounding ratio (% by weight) shown in Table 2 below.
6, trade name: Lenny 6000) was mixed with a twin-screw extruder set at 270 ° C., and extrusion granulated to obtain the composition of the present invention.

An injection pressure of 800 kg /
cm ² , molding temperature 290 ° C., injection amount 100 cm ³ / sec,
Injection molding was performed at a mold temperature of 130 ° C. to prepare a test piece for measuring physical properties.

The mechanical properties and electrical properties of the obtained test piece were examined. The results are shown in Table 2.

[Conditions for Measuring Mechanical and Electrical Properties] Variations in surface resistance and surface resistance (conductivity); JIS
According to K 6911. Then, the conductive variation in the test piece was evaluated according to the following criteria.

According to ASTM D790; [0037] ^{○ ... 1 × 10 -1.0 ~1 ×} 10 +1.0 Ω / □ range × of ^{... 1 × 10 -1.0 ~1 × 10} +1.0 Ω / □ outside bending strength.

Surface roughness: Measured with Surfcom 304B [Tokyo Seimitsu Co., Ltd.] with a measuring length of 8 mm for the plate for electrostatic coating property test (Rmax).

Comparative Example 1 Using each raw material shown in Table 2, a test piece was manufactured in the same manner as in Example 1 and the same test as above was conducted. The results are also shown in Table 2.

[0040]

[Table 2]

Example 2 PBT resin was used as the thermoplastic resin, and various tests were carried out in substantially the same operation as in Example 1. The results are shown in Table 3.

[0042]

[Table 3]

Example 3 As the potassium titanate fiber, antimony-doped, tin oxide-coated conductive potassium titanate fiber (fiber diameter 0.35) was used.
[mu] m, fiber length 15 [mu] m, using a specific resistance 10 ⁰ Ω · cm), and using the ABS resin as the thermoplastic resin, were subjected to various tests at substantially the same procedure as in Example 1. The results are shown in Table 4.

[0044]

[Table 4]

Example 4 Carbon fiber having an average diameter of 1.5 μm and an average length of 7.5 m
m, using ultrafine carbon fiber with a specific resistance of 10 ^-2 Ω · cm,
In addition, an ABS / PBT alloy resin was used as the thermoplastic resin, and various tests were performed in substantially the same operation as in Example 3. The results are shown in Table 5.

[0046]

[Table 5]

Example 5 A full-size ECG measuring toilet seat and ancillary parts were molded, and No. 3 of Example 3 was molded thereon. An electrode molded product obtained by molding the electrode material of 3 was attached. An example of this ECG-measuring toilet seat is shown in FIG. 1 and 2 in FIG. 1 are the positions where the electrode molded product is attached, and the thigh is placed at the position 1
The ECG can be measured by placing the palm on the second place. Using this toilet seat, the electrocardiogram of 5 persons was measured. The result is shown in FIG.

Example 6 Polyphenylene sulfide resin as carbon fibers having an average of 1.5 μm, an average length of 15 mm and a specific resistance of 10 ⁻² Ω · cm.
Conductive potassium titanate fiber (fiber diameter 0.3 μm, fiber length 15 μm) obtained by reducing and firing 7% by weight of ultrafine carbon fiber and potassium titanate fiber at 1000 ° C. in an inert atmosphere.
m, specific resistance 10 ⁻² Ω · cm) 7 wt%, polytetrafluoroethylene powder 5 wt%, ordinary carbon fiber 5 w
t% and Ketjen EC 0.5 wt% were kneaded by a twin-screw extruder set at 270 ° C., extruded, and granulated to obtain the composition of the present invention.

The composition of the present invention obtained above was injection molded into the shape shown in FIG. 3 to obtain a molded product. The surface skin layer of this molded product was measured and found to be 30 μm. Furthermore, this molded product was used in a part of the apparatus shown in FIG. 4 to measure impedance as an electrode material. Results are shown in FIG.

As is apparent from FIG. 5, the needle-shaped electrode prepared using the composition of the present invention had a uniform resistance value in each part, and the depth of the saline solution could be read electrically. .
In addition, by applying this property, it was effective to measure the depth of a narrow and fine portion, for example, the depth of the periodontal pocket.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of an electrocardiogram measurement toilet seat to which the molded electrode product of the present invention is attached.

FIG. 2 is an electrocardiogram of 5 persons measured by using an electrocardiogram measuring toilet seat to which the molded electrode product of the present invention is attached.

FIG. 3 is a side view of a molded product created in Example 6.

FIG. 4 is a schematic diagram of an apparatus for measuring impedance in Example 6.

FIG. 5 is a graph showing the relationship between the depth of a molded article immersed in physiological saline and the impedance.

[Explanation of symbols]

 1 Molded product for electrode of the present invention 2 Molded product for electrode of the present invention 3 Molded product of the present invention 4 Saline solution 5 Electrode

Claims (4)

[Claims] 1. A ceramic fiber having an average diameter of 0.01 to 3.0 μm, an average length of 1 to 500 μm, an average aspect ratio of 5 to 500, and a specific resistance of 10 ^{−3 to} 10 ⁴ Ω · cm, and / or The average diameter is 0.5 to 3.0 μm, and the average length is 0.
5-20 mm, average aspect ratio 200-1000
An electrode material comprising 0 to 50% by weight of carbon fiber having a specific resistance of 10 ^{−3 to} 10 ⁴ Ω · cm and the remainder being a thermoplastic resin. 2. A molded article for an electrode obtained by molding the material for an electrode according to claim 1. 3. The molded product according to claim 2, wherein the thickness of the surface skin layer is 200 μm or less. 4. A toilet seat having the molded article according to claim 3 attached to at least one part of the part that comes into contact with the skin.