JPH0947437A - Electrode for organism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode for organism which is used to transmit an electric signal from an organism to a medical diagnostic device, to introduce low-frequency to the organism as alleviating pain and a treatment, and has excellent film intensity, flexibility heat-resistance, and high-adhesion with an electric conductive coating material 2. SOLUTION: This electrode for organism is formed in such a manner that an electrode board is formed by using a polyolefin film 1 as a supporting body, and coating an electric conductive coating material 2 composed of carbon black and a polyolefinic resin on one side of this supporting body and an electric conductive adhesive layer 3 is formed on the electric conductive coating material-forming face of this electrode board.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biomedical electrode, and more particularly, to a biomedical electrode for therapeutic use such as applying a low-frequency weak current to a living body to relieve pain such as stiff shoulders and low back pain, and a weak electrode in a living body. The present invention relates to a biomedical electrode for use in a monitor such as an electrocardiograph that derives and measures an electric current.

[0002]

2. Description of the Related Art Conventionally, an electrode for a living body which is used to introduce a weak current due to a low frequency and an electric signal such as an electromagnetic wave due to a high frequency from the outside of the living body into the body to promote blood flow and to mainly treat the massage effect and the like , Bioelectric electrodes such as an electrocardiograph, an electroencephalograph, and an electromyography that take out and measure a weak current from a living body are known, and these electrodes are of an integrated type in which an electrode plate and a conductive adhesive are laminated. The structure is used.

Usually, in an electrode plate used for such a biomedical electrode, a metal layer such as silver / silver chloride is formed as a conductive layer on one surface (conductive adhesive layer forming side) of a plastic film as a support. In addition, a conductive coating material containing a metal such as aluminum, tin, or silver (white silver) or carbon black is formed.

However, when a metal layer is formed, it may be oxidized or corroded depending on the type of the conductive adhesive layer formed on the surface of the metal layer. Paints that use black as a filler are often used.

On the other hand, as the plastic film as the support, a single layer film such as a polyethylene film, a polyurethane film, an ethylene / vinyl acetate film, a vinyl chloride film or the like, as well as an actual Kaihei 5-33704.
A composite film obtained by laminating a plurality of films is used as described in Japanese Patent Publication (Kokai). Such a film is generally excellent in terms of mechanical strength, flexibility, heat resistance, adhesion of a conductive coating, etc., but since a polyester film is somewhat lacking in flexibility, it can be used in a bent part of the human body. There is a problem that the conductive pressure-sensitive adhesive layer is easily peeled off from the edge and the edge of the film comes into contact with the skin to easily cause skin irritation.

[0006] As a method for solving such a problem,
There is a method to improve the adhesive strength of the conductive adhesive, but in this case, when peeling and removing from the skin surface, even the stratum corneum is peeled off and the adhesive strength of the adhesive layer is extremely reduced. Therefore, it is not suitable when the same biomedical electrode is used many times. Therefore, the improvement of the support is the most suitable method for solving the above problems.

As a biomedical electrode having an improved support, there is a method using a polyurethane film as described in Japanese Utility Model Laid-Open No. 5-76452. The polyurethane film is more flexible than the polyester film, and has appropriate followability in accordance with the movement of the attached skin due to its appropriate elasticity. However, in applications where sticking and peeling are repeated many times, such as in the case of biomedical electrodes used in low frequency therapeutic devices, stress is applied to the interface between the polyurethane film and the conductive layer during peeling, and the polyurethane film is formed from conductive paint. There is a risk that the conductive layer may crack and the conductive layer may peel off.

If the thickness of the polyurethane film is thin, it becomes so-called stiff and difficult to handle. Therefore, it is necessary to use paper or another plastic film as a process paper to have a two-layer structure in order to provide support during production. Occurs,
The manufacturing process tends to be complicated. Further, when the support has a laminated structure of a polyurethane film and another film, there is a problem that curling occurs when heat is applied because the shrinkage ratio is different.

[0009]

SUMMARY OF THE INVENTION The present invention is intended to solve the above problems of the conventional biomedical electrode, and has the film strength, flexibility, heat resistance, and conductivity required for the biomedical electrode. An object of the present invention is to provide a biomedical electrode that has an electrode plate having excellent adhesiveness to a conductive coating material and can exhibit practically excellent conductivity.

[0010]

Means for Solving the Problems As a result of intensive studies conducted by the present inventors in order to achieve such an object, a polyolefin film was used as a support and carbon black and a polyolefin resin were formed on one side of the film. It has been found that a biomedical electrode capable of achieving the above object can be obtained by applying a conductive paint, and the present invention has been completed.

That is, according to the present invention, a conductive pressure-sensitive adhesive layer is formed on the paint forming surface of an electrode plate, which is formed by providing a conductive paint containing carbon black and a polyolefin resin on one side of a flexible polyolefin film. The present invention relates to a biomedical electrode.

The electrode plate used in the biomedical electrode of the present invention uses a polyolefin film as a support. As the polyolefin film in the present invention, an olefin homopolymer such as polyethylene or polypropylene, an olefin resin copolymerized with maleic acid, or a random copolymer of an olefin such as ethylene / vinyl acetate and another copolymerizable monomer is used. A film made of an olefin resin obtained by graft copolymerization of a copolymerizable monomer such as methacrylic acid can be used. The thickness of the film is 25-2
The thickness is about 00 μm, preferably about 50 to 150 μm. Among these, it is particularly preferable to use an unstretched polypropylene film from the viewpoint of imparting flexibility and heat resistance.

In the present invention, the conductive coating material applied and formed on one surface of the support film is a mixture of carbon black as a conductive material and a polyolefin resin as a binder material. Examples of carbon black that can be used include furnace black, acetylene black, channel black, and the like, which are compounded with a polyolefin resin as a binder substance to give 3 to 50 μm on one side of the polyolefin film.
Apply with a thickness of about m. The compounding amount of carbon black is usually 10 per 100 parts by weight of the polyolefin resin.
˜120 parts by weight, preferably 10 to 100 parts by weight. If the blending amount is less than 10 parts by weight, sufficient conductivity cannot be obtained, and if the blending amount is more than 120 parts by weight, the mechanical strength of the coating becomes poor. Generally, when printing a paint on a polyolefin film, there is a problem in that the coating film is likely to come off due to poor adhesion between the film and the coating film, and there is a problem in productivity due to shrinkage of the film due to heating during drying. Have. However, in the present invention, since the polyolefin resin is blended as the binder substance in the conductive paint, the affinity between the film and the coating film is good, and the adhesion is excellent. Moreover, since the conductive coating material used in the present invention is cured at a temperature of 60 ° C. or lower, heat shrinkage of the polyolefin film as the support hardly occurs. Moreover, the pencil hardness after curing has a hardness of B or more, and has practical mechanical strength that is strong against scratches and the like. In the biomedical electrode of the present invention, the electric resistance of the coating film is 1 × 10 ⁶ Ω or less, preferably 1 in order to exhibit practical conductivity.
× 10 ⁴ Ω or less. The electric resistance value can be adjusted by changing the type and blending amount of the polyolefin resin or carbon black in the conductive paint.

The polyolefin-based resin as the binder substance can uniformly contain carbon black as the conductive substance in the coating film, and the materials exemplified for the polyolefin film can be used. Further, in order to improve the adhesion between the film and the coating film, it is preferable to use the same polyolefin resin as the film material as the binder substance.

In the biomedical electrode of the present invention, the conductive pressure-sensitive adhesive to be adhered on the conductive coating film (conductive coating layer) of the electrode plate is not particularly limited, and for example, acrylic pressure-sensitive adhesive may be used as a metal powder or conductive material. Conventionally known conductive pressure-sensitive adhesives, such as those containing water-soluble carbon black, polyurethane gels, acrylamide gels, polyvinyl alcohol gels, etc. can be used. Of these, 1 from the viewpoint of conductivity
It is preferable to use a hydrogel type containing water in the range of 0 to 80% by weight, preferably 15 to 60% by weight, and 0.2 to 3 from the viewpoint of adhesiveness to the skin surface and shape retention.
It is provided with a thickness of about mm. When the water content is less than 10% by weight, the adhesion to the skin surface is improved, but the electric resistance value becomes large, which is not preferable as a biomedical electrode. On the other hand, if it exceeds 80% by weight, the adhesive force to the skin is reduced, and the internal cohesive force of the pressure-sensitive adhesive is reduced, which may contaminate the skin surface during peeling.

As the base material constituting the hydrogel-type conductive adhesive, it is preferable to use an acrylic polymer material from the viewpoint of aging stability of the adhesive, and particularly (meth) acrylic acid or a salt thereof. It is preferable to employ a polymer substance obtained by polymerizing as a monomer component. Specifically, poly (meth) acrylic acid such as polyacrylic acid, polymethacrylic acid, sodium polyacrylate, sodium polymethacrylate, (meth) acrylic acid or a salt thereof and a (meth) acrylic ester Examples thereof include polymers.

As the conductive adhesive, glycerin or a polyhydric alcohol such as (poly) ethylene glycol or (poly) propylene glycol is added in order to enhance the water retention on the skin surface and the adhesion to the skin surface. 20-80% by weight
It can be contained in the range of. In order to improve the internal cohesive force of the pressure-sensitive adhesive, a polyfunctional epoxy cross-linking agent having two or more epoxy groups in the molecule, such as triglycidyl isocyanate, polyethylene glycol diglycidyl ether, and glycerin diglycidyl ether, is further added. Various electrolytes such as lithium chloride, sodium chloride and potassium chloride can be appropriately mixed in order to improve conductivity.

The biomedical electrode of the present invention has the above-mentioned structure, and basically has the structure shown in FIG.
At the time of use, it suffices to connect a terminal for connection to an external device to the electrode plate. However, in order to simplify the connection operation, as shown in FIG. 2, it is preferable to provide the electrode plate with a snap for terminal connection, such as brass-plated nickel, and to separate the biomedical electrode from the skin surface. In order to make it easier, it is preferable to provide the snap at the peripheral portion rather than the central portion of the electrode plate. Further, when the snap is provided, the snap bottom, that is, the contact surface of the conductive adhesive may be corroded by the moisture in the adhesive, so a rust preventive paint may be applied to the contact surface, or the adhesive may be applied to the polyester film. It is preferable to apply the applied anticorrosion tape.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below and specifically described. In the following description, “part” in the text means “part by weight” and “%” means “% by weight”.

Example of production of electrode plate <Electrode plate a> A conductive paint (Doutite XC-32, polyolefin-based paint, carbon filler) manufactured by Fujikura Kasei Kogyo Co., Ltd. was applied to one side of a white polyethylene film having a thickness of 60 μm and the thickness after drying. To 20 μm, and dried at room temperature for 24 hours to prepare electrode plate a. The electrode plate showed no shrinkage phenomenon when dried, and the coating film had good adhesion. The pencil hardness of the coating film was B.

<Electrode plate B> A conductive paint (Doutite XC-32, polyolefin paint, carbon filler) manufactured by Fujikura Kasei Kogyo Co., Ltd. is coated on one side of a 60 μm thick unstretched polypropylene film to have a thickness of 20 μm after drying. And then dried at 50 ° C. for 1 hour to prepare an electrode plate b. The electrode plate showed no shrinkage phenomenon when dried, and the coating film had good adhesion. The pencil hardness of the coating film was B.

Production Example of Conductive Adhesive Layer <Adhesive Layer A> 20 parts of sodium polyacrylate was dispersed in 50 parts of glycerin, 30 parts of water was added and sufficiently stirred to prepare an adhesive solution. After adding 0.4 parts of triglycidyl isocyanate as a cross-linking agent to this solution and stirring sufficiently, it was dried on a polyester separator,
Apply it so that the thickness after cross-linking is 1.0 mm
A conductive pressure-sensitive adhesive layer A was prepared by drying at 0 ° C., crosslinking, and cutting into a size of 50 mm × 50 mm. The electric resistance value of this adhesive layer was 25Ω.

<Adhesive layer B> 1 part of potassium persulfate was dissolved in 350 parts of water, and a solution prepared by adding 95 parts of acrylic acid and 5 parts of acrylic acid butyl ester was placed in a flask and placed under an inert gas atmosphere. Polymerization was carried out for 8 hours while maintaining the reaction temperature at 60 ° C. After completion of the reaction, water was evaporated to obtain a copolymer powder, 15 parts of this powder was dispersed in 60 parts of polyethylene glycol, and 25 parts of water was further added and stirred to prepare an adhesive solution. To this solution was added 0.3 part of triglycidyl isocyanate as a cross-linking agent, stirred sufficiently, dried on a polyester separator, coated so that the thickness after cross-linking would be 1.0 mm, and dried at 100 ° C. Then, it was crosslinked and cut into a size of 50 mm × 50 mm to prepare a conductive adhesive layer B. The electric resistance value of this adhesive layer was 120Ω.

The electrode plate and the conductive pressure-sensitive adhesive layer obtained above were combined to prepare a biomedical electrode of the present invention, and the results are shown in Table 1. As a comparative example, a conductive coating (Doutite FC-404CA, polyester-based coating, carbon filler) manufactured by Fujikura Kasei Kogyo Co., Ltd. was formed on one surface of a polyester film having a thickness of 75 μm and the thickness after drying was 20 μm.
And the electrode plate c obtained by drying at 100 ° C. for 10 minutes, and an electrode plate d of 500 μm thick silver vapor-deposited on a 50 μm-thick polyester film. It was produced and the results are also shown in Table 1.

The measuring method of each characteristic in Table 1 is as follows.

<Corrosion resistance> Each biological electrode was hermetically sealed and stored at 40 ° C. for one month, the adhesive layer was peeled off from the electrode plate, and the corrosion of the conductive coating layer of the electrode plate was visually observed. Then, it was judged according to the following criteria.

◯: No corrosion was observed. X: Corrosion was confirmed.

<Flexibility> Each biomedical electrode cut into a size of 40 mm × 70 mm was adhered to the upper arm, and the adhered state 1 hour after the adhesion was visually observed and judged according to the following criteria. . ◯: The electrodes are firmly attached.

Δ: A slight floating is seen at the end of the electrode. X: Both ends of the electrode are considerably raised.

<Adhesiveness> The pressure-sensitive adhesive layer was peeled off from the electrode plate and the peeled state was observed, and the judgment was made according to the following criteria. ◯: Adhesion is good, and the adhesive layer remains on the electrode. Δ: Good adhesion, but the adhesive does not remain on the electrode plate.

X: Easy peeling

<Electrical resistance value> After peeling the polyester separator from the biomedical electrode and pasting the measuring electrode on the copper plate, the terminal connection part of the electrode plate and the copper plate are sandwiched by metal cords respectively, and Hewlett-Packard Impedance was measured under the conditions of an applied voltage of 1 V and a measurement frequency of 1 kHz using a LCR meter manufactured by the same company. The electrode area is 50 mm
The size was × 50 mm.

[0033]

[Table 1]

[0034]

Since the biomedical electrode of the present invention has the above-mentioned structure, the electrode plate and the conductive pressure-sensitive adhesive layer are bonded extremely well integrally, and the operability is excellent. In addition, since the polyolefin film is coated with a conductive paint having a specific composition, it is highly flexible, has less corrosion of the electrode plate, and has a small electrical resistance value and highly reliable conduction.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a biomedical electrode of the present invention.

FIG. 2 is a cross-sectional view showing another embodiment of the biomedical electrode of the present invention.

[Explanation of symbols]

 1 Polyolefin Film 2 Conductive Paint Layer (Coating Film) 3 Conductive Adhesive Layer 4 Separator 5 Snap 6 Anticorrosion Sheet

Claims (3)

[Claims] 1. A biomedical electrode in which a conductive pressure-sensitive adhesive layer is formed on the paint forming surface of an electrode plate which is provided with a conductive paint containing carbon black and a polyolefin resin on one side of a flexible polyolefin film. . 2. The biomedical electrode according to claim 1, wherein the conductive paint is cured at a temperature of 60 ° C. or lower, and the pencil hardness after curing is B or higher. 3. The living body according to claim 1, wherein the polyolefin-based film is one selected from an olefin homopolymer and a polyolefin-based copolymer obtained by graft-copolymerizing or random-copolymerizing another copolymerizable monomer. Electrodes.