JP2021052868A - Electrode pad - Google Patents

Abstract

To provide an electrode pad in which swelling of gels is suppressed, and an electrode pad capable of reducing damage to the skin more substantially.SOLUTION: An electrode pad 1A used by being stuck to a living body surface for allowing current to flow through a living body includes: a surface material 10; a conductive layer 20 laminated in a region excluding a peripheral edge part of the surface material 10; and an adhesive gel layer 30 laminated on the whole surface of the surface material 10 while covering the conductive layer 20. The thickness deviation is 0.4 mm or less, and at least the outer periphery of the adhesive gel layer 30 is formed of a high water content adhesive gel containing 10-60 wt.% of water.SELECTED DRAWING: Figure 2

Description

The present invention relates to an electrode pad used by being attached to the surface of a living body in order to pass an electric current through the living body.

Electrode pads for passing an electric current to a living body are used in monitoring equipment such as electrocardiogram measurement, medical electrodes used when performing treatment using electrical stimulation such as low frequency and medium frequency, and electrosurgical scalpel devices. ing. For example, an electrosurgical knife device is composed of an electrosurgical knife that is electrically connected to a device body having a high frequency generating circuit and an electrode pad that is electrically connected to the device body and is used as a counter electrode of the electrosurgical knife (patented patent). Documents 1 and 2). The electrode pad is used by being attached to the surface of a living body, and is an earth electrode that recovers a high-frequency current flowing from the main body of the device through the female tip electrode of an electric knife to the living body by reducing the current density over a wide area.

In the conventional electric knife, the current density at the counter electrode is low because the current is passed through a narrow portion and the current is recovered by the electrode pad which is the counter electrode of a wide area. However, in recent years, it has become possible to use a mode in which a protein is denatured to ensure thermal coagulation without carbonizing the tissue, and a current is passed over a relatively wide range, so that the current density of the counter electrode is increasing.

As a conventional electrode pad, Patent Document 3 describes an electrode pad that is attached to a living body as a counter electrode of an electric knife, has an adhesive layer on the side to be attached to the living body, and can be connected to a lead wire. The present invention includes a surface material having a tongue piece portion provided at an end portion, a conductive layer laminated on a region excluding a peripheral portion on the surface material, and an adhesive gel layer laminated on the conductive layer. When the area of the adhesive gel layer is S1 and the area of the surface material is S2, 50% ≦ 100 × S1 / S2 ≦ 95%, and the width b of the peripheral edge portion on the surface material is 4 mm or more. An electrode pad having an adhesive strength B of 15 mm or less, an adhesive strength B of the pressure-sensitive adhesive layer of 3N / 20 mm or more and 9N / 20 mm or less, and a B × b value of 20 N ・ mm / 20 mm or more and 80 N ・ mm / 20 mm or less is disclosed. ing.

Japanese Patent No. 3714982 Japanese Unexamined Patent Publication No. 2007-175159 Japanese Unexamined Patent Publication No. 2019-34128

Conventionally, when the electrode pad is peeled off from the skin after use, there is a risk of skin damage due to strong adhesive force, especially in elderly people, infants, etc. However, the electrode pad described in Patent Document 3 described above has a risk of causing skin damage. By setting the adhesive strength and area ratio of the constituent members (adhesive gel, surface material) of the electrode pad within a specific range, damage to the skin when the electrode pad is peeled off is alleviated.

However, since the electrode pad of Patent Document 3 still has an adhesive layer for fixing to the skin at the peripheral edge of the surface material, it is due to the adhesive strength of the adhesive layer for elderly people and people with weak skin. There is a concern that the keratin may come off and skin damage such as skin irritation may occur, and further improvement is desired.

Further, as shown in FIG. 4, in the conventional electrode pad 400, the pressure-sensitive adhesive layer 402 is provided on the surface material 401, and the conductive film 403a and the electrode element 403b are formed in a region excluding the peripheral edge portion on the surface material 401. The layer 403 and the adhesive gel layer 404 are sequentially laminated and have a structure covered with a peelable cover film 405. Therefore, a step is formed between the pressure-sensitive adhesive layer 402 and the pressure-sensitive gel layer 404 at the peripheral portion. Due to this step, when the electrode pad 400 is attached to the skin, the pressure of the adhesive gel layer 404 on the skin may be increased.

Further, for example, during an operation, a drug solution such as physiological saline or blood that flows down may infiltrate from around the electrode pad to which the electrode pad is attached and permeate the electrode pad. In that case, conventionally, there is a risk that the gel will swell and the adhesion of the electrode pad will be weakened and peeled off. Therefore, it has been desired to suppress the swelling of the gel and reduce the risk of the electrode pad peeling off. Further, when the adhesive on the peripheral edge and the gel come into contact with each other at the edge, the adhesive on the peripheral edge and the plasticizer contained in the gel may be mixed and lack stability.

Therefore, an object of the present invention is to provide an electrode pad in which swelling of gel is suppressed. Another object of the present invention is to provide an electrode pad capable of further reducing damage to the skin.

As a result of diligent studies by the present inventors, it was found that the above problems can be solved by changing the shape of the adhesive gel layer in the electrode pad and optimizing the composition of the adhesive gel layer. Was completed. That is, the gist of the present invention is as follows.

(1) An electrode pad used by being attached to the surface of a living body in order to pass an electric current through the living body.
Surface material and
A conductive layer laminated in a region excluding the peripheral portion on the surface material, and
It has an adhesive gel layer laminated on the entire surface of the surface material while covering the conductive layer.
The thickness deviation is 0.4 mm or less,
The electrode pad in which at least the outer peripheral portion of the adhesive gel layer is made of a highly water-containing adhesive gel containing 10 to 60% by weight of water.
(2) The electrode pad according to (1) above, wherein the adhesive gel layer has the same composition in the outer peripheral portion and other portions.
(3) The electrode pad according to (1) or (2) above, wherein the highly water-containing adhesive gel has a swelling rate of 130% or less when exposed to an environment of 40 ° C. and 90% RH for 1 hour.
(4) The above-mentioned (1) to (3), wherein the highly water-containing adhesive gel has a swelling rate of 200% or less when exposed to an environment of 40 ° C. and 90% RH for 12 hours. Electrode pad.
(5) The above (1) to (4), wherein the highly water-containing adhesive gel is a hydrogel containing a polymer matrix, water and a plasticizer, and the plasticizer is a polyoxyalkylene alkyl ether and / or sugar. The electrode pad according to any one of.
(6) The polyoxyalkylene alkyl ether is at least one selected from the group consisting of polyoxyethylene methylglucoside and polyoxyethylene alkyl ether, and the sugar is selected from the group consisting of monosaccharides, disaccharides and polysaccharides. The electrode pad according to (5) above, which is at least one kind of electrode pad.
(7) The electrode pad according to (5) or (6) above, wherein the content of the plasticizer is 10 to 60% by weight with respect to 100% by weight of the total amount of the hydrogel.
(8) The electrode pad according to any one of (1) to (7) above, which is used as the counter electrode of the electric knife in the electric knife device.

In the electrode pad of the present invention, since the adhesive gel layer contains a highly water-containing adhesive gel, water resistance is improved, swelling of the gel is suppressed, and a decrease in adhesive strength is prevented.

Furthermore, since the adhesive gel layer is laminated on the entire surface of the surface material and the thickness deviation is reduced, there is no damage to the skin due to the conventional adhesive layer, and the pressure is not concentrated on a part of the skin, so that the skin is not affected. A gentle electrode pad can be obtained.

It is a top view which shows one Embodiment of the electrode pad which concerns on this invention. FIG. 1 is a cross-sectional view taken along the line AA'in FIG. It is sectional drawing which shows another embodiment of the electrode pad which concerns on this invention. It is sectional drawing of the conventional electrode pad.

Hereinafter, the present invention will be described in detail based on the embodiments.
FIG. 1 is a plan view of an embodiment of the electrode pad according to the present invention. FIG. 2 is a cross-sectional view taken along the line AA'of FIG. This electrode pad 1A is used as a counter electrode of an electric knife in an electric knife device (not shown). The electromesh device is composed of a device main body having a high frequency generating circuit, an electric knife electrically connected to the device main body by a lead wire, and an electrode pad 1A electrically connected to the device main body by a lead wire L. It is composed. When using an electrosurgical knife, the electrode pad 1A is attached to the surface of a living body such as a patient, a high-frequency current is applied between the electrode pad 1A and the electrosurgical knife from the device body, and incision and coagulation are performed at the tip of the electrosurgical knife. I do. Since the configuration of the electric knife and the main body of the device is the same as the conventional one, the description thereof will be omitted.

As shown in FIGS. 1 and 2, the electrode pad 1A according to the present embodiment has a surface material 10 provided with a tongue piece portion 101 connectable to a lead wire L at an end portion and a peripheral portion on the surface material 10. It is roughly composed of a conductive layer 20 laminated in a region other than the above, and an adhesive gel layer 30 laminated on the entire surface of the surface material 10 while covering the conductive layer 20. Further, a transparent cover film 40 is detachably laminated on the adhesive gel layer 30, and the adhesive gel layer 30 is covered with the adhesive gel layer 30 to protect the adhesive gel layer 30 and prevent drying. There is. Further, in the present embodiment, the peeling convex piece 102 is formed at the corner portion of the surface material 10. In this peeling convex piece 102, the adhesive gel layer 30 does not exist on the surface material 10, but since the cover film 40 is laminated, the peeling convex piece 102 is picked up when the electrode pad 1A is used. The entire cover film 40 can be easily peeled off by peeling.

As the surface material 10, a resin film having morphological properties and flexibility can be used, for example, a non-conductive film such as a polyethylene terephthalate film, a polypropylene film, a polyethylene film, paper, a non-woven fabric, a foam sheet, or the like, or them. Can be mentioned, such as a composite sheet in which the above is laminated. In order to improve the appearance as an electrode pad, cosmetic printing may be applied. The thickness of the surface material 10 is preferably about 10 μm to 200 μm from the viewpoint of handleability, but is not limited to this.

The conductive layer 20 is laminated and integrated in a region on the surface material 10 excluding the peripheral edge portion, and can be connected to the lead wire L at the connecting portion 201 formed on the tongue piece portion 101 of the surface material 10. .. The method of connecting the lead wire L and the conductive layer 20 is not particularly limited. For example, a method of crimping one end of the lead wire L to the conductive layer 20, or a connecting tool for connecting the conductive layer 20 and the lead wire L in a state of being overlapped as disclosed in Japanese Patent Application Laid-Open No. 2007-175159. Can be used separately, and a method of holding the conductive layer 20 and the lead wire L in a sandwiched state or the like can be appropriately adopted. Further, if necessary, the connecting portion between the lead wire L and the conductive layer 20 is insulated by winding with an insulating tape so that one end of the lead wire L and the conductive layer 20 do not come into contact with the living body and cause an electric shock. Can be processed.

In the present embodiment, the conductive layer 20 is composed of a laminate of a resin film 20a such as a polyethylene terephthalate film and an electrode element 20b. The resin film 20a is used as a reinforcing material for the electrode element 20b, and can maintain the function of the electrode element 20b even when the conductive layer 20 is deformed along the surface of the living body. The electrode element 20b is not particularly limited as long as it has a small electrical resistance, and for example, a metal foil such as an aluminum foil, a stainless foil, a copper foil, or a nickel foil can be applied, or carbon, silver, or silver chloride. The conductive material such as the above can be formed by coating it in a layer on the resin film 20a together with a binder such as a synthetic resin. The electrode element 20b is preferably made of a metal foil from the viewpoint of conductivity, and more preferably an aluminum foil is used from the viewpoint of lightness, cost, safety, workability and the like. Alternatively, as another embodiment, the conductive layer 20 may be composed of only the electrode element 20b.

In the present embodiment, if the thickness of the conductive layer 20 is too thick, the flexibility may decrease and the electrode pad 1A may not be deformed along the living body, and the adhesion of the electrode pad 1A to the living body may decrease. Yes, if it is too thin, the mechanical strength may decrease, so it is set appropriately in consideration of these balances. It is preferably 3 μm or more and 25 μm or less, and particularly preferably 9 μm or more and 15 μm or less. Here, the thickness of the conductive layer 20 refers to the thickness of the electrode element 20b when the conductive layer 20 is a laminate of the resin film 20a and the electrode element 20b, and the conductive layer 20 is formed only by the electrode element 20b. In this case, it refers to the thickness of the electrode element 20b.

In the present embodiment, as shown in FIGS. 1 and 2, the conductive layer 20 is divided into a predetermined area, and the lead wire L is connected to each of the conductive layers 20 at the tongue piece portion 101. Since the conductive layer 20 is divided into two and the lead wire L is connected to each conductive layer, even if one lead wire L is separated from the conductive layer 20 during use of the electrode pad 1A, the other lead wire L Maintains an electrical connection with the conductive layer 20. However, the present invention is not limited to the one in which the conductive layer is divided into two.

In the electrode pad 1A according to the present embodiment, the conductive layer 20 is laminated in a region excluding the peripheral edge portion on the surface material 10, but the width of the peripheral edge portion (from the end portion of the surface material 10 to the end portion of the conductive layer 20). The distance to) may be as long as it does not allow the chemical solution or the like to infiltrate from the surroundings and come into contact with the conductive layer 20 during use of the electrode pad 1A, and should be appropriately set according to the components of the adhesive gel layer 30 and the like. Can be done. Specifically, for example, as shown in FIG. 1, the area of the conductive layer 20 is S1, and the area of the surface material 10 (including the region where the conductive layer 20 and the adhesive gel layer 30 are laminated on the surface material 10). When the area of the entire surface material 10 is S2, it is preferable to secure the width of the peripheral edge portion so that 50% ≦ 100 × S1 / S2 ≦ 95%. More preferably, it is 60% ≦ 100 × S1 / S2 ≦ 80%. By setting this range, the area of the conductive layer 20 is sufficiently secured, the current density when used as the counter electrode of the electric knife is not increased, and the heat generation of the electrode pad 1A can be suppressed.

The area S1 of the conductive layer 20 and the area S2 of the surface material 10 are the tongue piece portion 101 formed at the end of the surface material 10 and the convex piece 102 for peeling on the surface of the surface material 10 in FIG. It shall be calculated for the part excluding.

Further, although not shown, the surface material 10 and the resin film 20a of the conductive layer 20 may be in close contact with each other via an adhesive layer. As the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer, various conventionally known pressure-sensitive adhesives can be applied. Specifically, for example, a rubber-based pressure-sensitive adhesive, a vinyl acetate-based pressure-sensitive adhesive, an ethylene-vinyl acetate-based pressure-sensitive adhesive, and the like. Examples thereof include polyvinyl alcohol-based adhesives, polyvinyl acetal-based adhesives, acrylic-based adhesives, polyamide-based adhesives, polyethylene-based adhesives, and cellulose-based adhesives.

Then, as shown in FIG. 2, the electrode pad 1A according to the present embodiment includes the adhesive gel layer 30 on the entire surface of the surface material 10 while covering the conductive layer 20. The adhesive gel layer 30 can be applied as long as it is a gel having adhesive strength to a living body. Since the adhesive gel layer 30 is laminated on the entire surface including the peripheral portion of the surface material 10, the adhesive layer on the peripheral portion does not come into contact with the skin as in the conventional case, and the adhesive is less irritating to the skin. Since only the sex gel layer 30 is in contact, the risk of skin damage can be reduced. Further, by forming the adhesive gel layer 30 on the peripheral edge of the surface material 10, there is no step at the end of the conductive layer 20, or the step is slight, and the region of the conductive layer 20 protrudes in the thickness direction. Eliminates excessive pressure on the skin. In the present invention, slits or the like may be formed in the adhesive gel layer 30 as long as the effect is not hindered. By forming a slit or the like, the contact area between the adhesive gel layer 30 and the skin can be reduced while avoiding the conventional contact of the adhesive layer with the skin, and the irritation to the skin can be further reduced. ..

The thickness h of the electrode pad 1A may be a value as long as the adhesive gel layer 30 can exert sufficient adhesive force on the surface of the living body, and can be appropriately set in consideration of the thickness of each layer. For example, the thickness h is preferably in the range of 0.5 to 2.0 mm, but is not limited to this range. In the present specification, the thickness h is the thickness at any 5 points on the peripheral edge portion on the electrode pad 1A and any 5 points on the conductive layer including the peripheral edge portion of the surface material 10 and the region where the conductive layer 20 is provided. And say the average value of them. Further, from the viewpoint of reducing the pressure on the skin, the deviation of the thickness h is set to 0.4 mm or less. It is preferably 0.3 mm or less. Here, the deviation of the thickness h, any average of values measured at each 5 points each h _{a (peripheral} portion) of the peripheral portion and the conductive layer of the above, when the h b _(conductive layer), | h _b It _{refers to the value of −h a} |, and the value of | h _b −h _a | is required to be 0.4 mm or less.

Further, in the present embodiment, the adhesive strength of the adhesive gel layer 30 varies depending on the use and size of the electrode pad 1A, but is preferably 1.0 N / 20 mm or more and 6.0 N / 20 mm or less. Within this range, the electrode pad 1A can be reliably fixed to the surface of the living body. The adhesive strength of the adhesive gel layer 30 refers to the adhesive strength when peeled off by 90 ° according to the adhesive tape test method of JIS Z 0237: 2009. However, the adherend uses a bakelite plate having a thickness of 2 mm and a length of 125 mm, and the adhesive frame width is 20 mm.

The adhesive gel layer 30 is formed by applying a pre-gelling compounding solution on the surface material 10 on which the conductive layer 20 is laminated and cross-linking the mixture, and also forming the adhesive gel layer 30 as a coating film on the cover film 40. 30 may be formed by superimposing the 30 on the surface material 10 on which the conductive layer 20 is laminated.

As described above, the adhesive gel layer 30 is a gel having adhesive strength to a living body, and at least the outer peripheral portion of the adhesive gel layer 30 is made of a highly water-containing adhesive gel containing 10 to 60% by weight of water. .. It is preferably 15 to 50% by weight. In the embodiment shown in FIG. 2, not only the outer peripheral portion of the adhesive gel layer 30 but also the portion other than the outer peripheral portion, that is, the adhesive gel layer 30 located on the conductive layer 20, has the same composition as the outer peripheral portion. It is composed of a water-containing adhesive gel. If the water content is too small, the water content of the gel is too small with respect to the equilibrium water content of the gel, so that the hygroscopicity becomes strong and the gel may deteriorate over time. On the other hand, if the water content is too large, the difference from the equilibrium water content of the gel becomes large, and there is a risk that the gel shrinks due to drying and changes in physical properties occur. Since the outer peripheral portion of the adhesive gel layer 30 is composed of a highly water-containing adhesive gel containing 10 to 60% by weight of water, the water resistance of the outer peripheral portion is improved, and a chemical solution such as physiological saline or blood or the like is an electrode. When the gel penetrates from the periphery of the pad 1A, the swelling of the gel is suppressed, and as a result, the adhesion force of the electrode pad 1A is reduced and the risk of peeling can be reduced.

The highly water-containing adhesive gel is preferably a hydrogel containing a polymer matrix and a plasticizer in addition to the above-mentioned water. The plasticizer runoff ratio is less than 2, the swelling rate when exposed to an environment of 40 ° C. and 90% RH for 1 hour is 130% or less, and the exposure to an environment of 40 ° C. and 90% RH for 12 hours. The swelling rate is preferably 200% or less. Further, it is preferable that the initial adhesive force to the Bakelite plate according to the adhesive tape test method of JIS Z 0237: 2009 is 1N / 20 mm or more. More preferably, the plasticizer washout ratio is less than 1.90, the swelling rate after 1 hour exposure is 110% or less, and the swelling rate after 12 hours exposure is 170% or less. The initial adhesive strength is more preferably 2N / 20 mm or more. More preferably, the swelling rate after exposure for 12 hours is 130% or less. When the plasticizer runoff ratio and the swelling rate are within the above ranges, the infiltration of water from the outside of the hydrogel is suppressed, and the initial high adhesive strength can be maintained even in a high humidity environment. Specifically, the adhesive strength after exposure to an environment of 40 ° C. and 90% RH for 1 hour is 60% or more, preferably 70% or more, with respect to the initial adhesive strength. Further, the adhesive strength after exposure to an environment of 40 ° C. and 90% RH for 12 hours is 30% or more, preferably 50% or more. Next, each component constituting the hydrogel as a highly water-containing adhesive gel will be described.

(Polymer matrix)
The polymer matrix is not particularly limited as long as it can form a network structure and can form a gel containing at least water. Synthetic polymers that can be applied to the skin can be applied. As a suitable example, it can be formed from a copolymer of a monofunctional monomer having one ethylenically unsaturated group and a crosslinkable monomer.

As the monofunctional monomer, a monomer such as (meth) acrylamide-based monomer, (meth) acrylic acid ester-based monomer, (meth) acrylic acid or a salt thereof is preferably used. Any of these compounds may be used alone, or two or more thereof may be used in combination.

Specific examples of the (meth) acrylamide-based monomer include N, N-dialkyl (meth) acrylamide such as (meth) acrylamide, N, N-dimethyl (meth) acrylamide and N, N-diethyl (meth) acrylamide; N-alkyl (meth) acrylamides such as N-isopropyl (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide and N-propyl (meth) acrylamide; N-hydroxyethyl (meth) acrylamide and N-hydroxyalkyl (meth) acrylamide such as N-hydroxymethyl (meth) acrylamide; amino group-containing cationic acrylamide compounds such as dimethylaminopropyl (meth) acrylamide; 4-acrylloylmorpholine and tert-butylacrylamide sulfonic acid The sulfonic acid group-containing anionic monofunctional monomer or a salt thereof; and derivatives thereof and the like can be mentioned. Each of these monofunctional monomers may be used alone, or two or more kinds of monomers may be used in combination.

Specific examples of the (meth) acrylic acid ester include (meth) acrylic acid alkyl esters having an alkyl group having 1 to 18 carbon atoms, such as methyl (meth) acrylic acid, ethyl (meth) acrylic acid, and (meth) acrylic acid. N-propyl acid, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate; 2-methoxyethyl (meth) acrylate, (meth) (Meta) Acrylic acid ester containing an alkoxy group such as (meth) methoxypolyethylene glycol (meth) such as ethoxyethoxyethyl acrylate and methoxytriethylene glycol (meth) acrylate; 2-hydroxyethyl (meth) acrylate, (meth) (The aryl group may be bonded to the hydroxyalkyl group via an ether bond) such as 2-hydroxypropyl acrylate (meth) hydroxyalkyl acrylate; glycerin mono (meth) acrylate; mono (meth) acrylic acid. Polyalkylene glycol mono (meth) acrylic acid such as polyethylene glycol and polyethylene glycol-polypropylene glycol copolymer; (meth) acrylic acid ester having an aromatic ring such as benzyl (meth) acrylic acid can be mentioned. Each of these monofunctional monomers may be used alone, or two or more kinds of monomers may be used in combination.

Specific examples of (meth) acrylic acid or a salt thereof include acrylic acid, methacrylic acid, sodium acrylate, potassium acrylate, potassium methacrylate and the like. Each of these monofunctional monomers may be used alone, or two or more kinds of monomers may be used in combination.

In the hydrogel, the total content of the structural units derived from the monofunctional monomer is not particularly limited, but is preferably in the range of 10 to 50% by weight with respect to 100% by weight of the total amount of the hydrogel. More preferably, it is in the range of 15 to 45% by weight. If the total content of the structural units derived from the monofunctional monomer in the hydrogel is too small, the shape retention of the hydrogel may be insufficient, and the hydrogel may be too soft or easily torn. Further, if the total content of the structural units derived from the monofunctional monomer in the hydrogel is too large, the hydrogel may become hard and the flexibility may be impaired.

The crosslinkable monomer is not particularly limited, but a compound having two or more polymerizable carbon-carbon double bonds in the molecule is preferable, and for example, divinylbenzene, divinylbiphenyl, N, N'-methylenebis ( Examples thereof include meta) acrylamide, ethylene glycol di (meth) acrylate, glycerin tri (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, and polyglycerin di (meth) acrylate. Any of these compounds may be used alone, or two or more thereof may be used in combination.

In the hydrogel, the content of the structural unit derived from the crosslinkable monomer is not particularly limited and varies depending on the type of the monofunctional monomer and the crosslinkable monomer used, but the total amount of the hydrogel is 100. It is preferably in the range of 0.01 to 0.5% by weight, more preferably in the range of 0.01 to 0.1% by weight, based on% by weight. If the content of the structural unit derived from the crosslinkable monomer in the hydrogel is too small, the crosslink density may be low and the shape stability of the gel may be poor. Further, if the content of the structural unit derived from the crosslinkable monomer in the hydrogel is too large, the gel tends to be hard and brittle.

(Plasticizer)
The plasticizer imparts moisturizing power to the hydrogel, suppresses the evaporation of water, and maintains the flexibility of the gel. As such a plasticizer, a compound that is relatively hydrophobic (hydrophilic as an absolute index) can be used as compared with conventional polyhydric alcohols such as glycerin. Specifically, it is preferable to use polyoxyalkylene alkyl ether and / or sugar. These compounds have a composition closer to hydrophobicity than polyhydric alcohols, can reduce the infiltration of water into the hydrogel from the outside, and can suppress the swelling of the gel.

As a polyoxyalkylene alkyl ether, the general formula:
_{H 2m + 1 C m -O- (} C n H 2n -O) x -H
A linear polyoxyalkylene alkyl ether represented by is applicable. In the above general formula, m is preferably 1 to 20, n is 2 to 3, and x is preferably in the range of 2 to 50. Specific examples of the linear polyoxyalkylene alkyl ether include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, and polyoxyethylene isostearyl ether, polyoxypropylene lauryl ether, and polyoxy. Examples thereof include polyoxypropylene alkyl ethers such as propylene stearyl ether and polyoxypropylene isostearyl ether.

Further, as another example of the polyoxyalkylene alkyl ether, a cyclic (multi-chain type) polyoxyalkylene alkyl ether such as polyoxyethylene methyl glucoside or polyoxypropylene methyl glucoside can also be applied. These linear or multi-chain polyoxyalkylene alkyl ethers may be used alone or in combination of two or more.

Further, as the sugar, one or more selected from the group consisting of monosaccharides, disaccharides and polysaccharides can be used. Examples of monosaccharides include xylose, arabinose, glucose, galactose, mannose and the like, examples of disaccharides include sucrose, maltose, cellobiose and lactose, and examples of polysaccharides include oligosaccharides such as maltotriose. Examples thereof include xylan, starch, cellulose, chitin, chitosan and the like. Amino sugars of these sugars and their N-acetylated products are also applicable. Regardless of the D form and the L form, any two or more of them may be used in combination.

The content of the plasticizer varies depending on the type of the plasticizer and is not particularly limited, but is preferably in the range of 10 to 60% by weight, particularly preferably, with respect to 100% by weight of the total amount of the hydrogel. 20 to 50% by weight. If the content of the plasticizer in the above hydrogel is too small, the moisturizing power of the gel is poor, the evaporation of water becomes remarkable, and the gel lacks stability and flexibility over time, so that the gel may not be able to maintain its adhesive strength. is there. On the other hand, if the content of the plasticizer in the hydrogel is too large, the plasticizer may bleed out to the surface of the gel.

The content ratio of the polymer matrix and the plasticizer is not particularly limited, but the weight ratio is preferably in the range of 0.25: 1 to 3.0: 1, and 0.45: 1 to 2.5 :. It is more preferably within the range of 1.

(Water-soluble polymer)
The hydrogel may contain a water-soluble polymer, if necessary. Applicable water-soluble polymers are not particularly limited, but are, for example, homopolymers of vinylpyrrolidone (ie, polyvinylpyrrolidone); copolymers of vinyl alcohol and vinylpyrrolidone, ether-modified vinyl alcohol and vinylpyrrolidone. Vinyl pyrrolidone copolymers such as copolymers, copolymers of vinyl pyrrolidone and vinyl acetate; polyvinyl alcohol, polyacrylic acid, sodium polyacrylate, sodium carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, sodium alginate, dextran, etc. Can be mentioned. Any one of these water-soluble polymers can be used alone or in combination of two or more.

Among the water-soluble polymers, polyacrylic acid and / or sodium polyacrylate are excellent in the effect of imparting adhesiveness to the hydrogel. When the hydrogel contains polyacrylic acid and / or sodium polyacrylate, the content of polyacrylic acid and / or sodium polyacrylate (the total amount when both are contained) is 100 in the total amount of the hydrogel. It is preferably in the range of 0.1 to 5% by weight with respect to% by weight. If the content of the water-soluble polymer in the hydrogel is too large, not only the handling becomes difficult due to the increase in the viscosity of the entire system, but also the effect commensurate with the added amount cannot be obtained.

(Electrolytes)
The hydrogel can contain an electrolyte, if desired. By blending an electrolyte, conductivity is imparted to the hydrogel. As described above, in the highly water-containing adhesive gel containing 10 to 60% by weight of water, the electrolyte is easily dissolved, and therefore the electrical characteristics of the adhesive gel layer 30 can be improved. The specific resistance of the hydrogel containing the electrolyte is preferably in the range of 0.01 to 100 kΩ · cm.

The electrolyte is not particularly limited, and examples thereof include salts. Examples of the salt include alkali metal halides such as sodium halide (for example, sodium chloride), lithium halide and potassium halide; alkaline earth metals halide such as magnesium halide and calcium halide; and other metal halogens. Compounds: Hypochlorites, chlorates, chlorates, perchlorates, sulfates, carbonates, nitrates, phosphates of various metals; Inorganic salts such as ammonium salts and various complex salts; Acetic acid, benzo Salts of monovalent organic carboxylic acids such as acids and lactic acid; monovalent or divalent or higher salts of polyvalent carboxylic acids such as tartaric acid, phthalic acid, succinic acid, adipic acid and citric acid; organic acids such as sulfonic acid and amino acids Metal salts; organic ammonium salts; salts of high molecular weight electrolytes such as poly (meth) acrylic acid, polyvinyl sulfonic acid, polyterriary butyl acrylamide sulfonic acid, polyallylamine, polyethylene imine; and the like.

Further, as the electrolyte, a substance that is insoluble at the time of blending the hydrogel and has a property of being dissolved in the hydrogel over time may be used even if it is in a dispersed form during the preparation of the blending solution. Examples of such an electrolyte include silicates, aluminates, metal oxides, hydroxides and the like.

The content of the electrolyte in the hydrogel is preferably in the range of 0.001 to 10% by weight, preferably in the range of 0.1 to 5% by weight, based on 100% by weight of the total amount of the hydrogel. Is more preferable. A hydrogel containing water originally has characteristics as a dielectric, and when an electrode pad is produced by combining with an electrode element, it has an electric capacity according to the thickness of the gel and the area of the electrode element. However, the impedance (Z) of the hydrogel is greatly affected by the electrolyte concentration, especially in the low frequency region of less than 1 kHz. If the content of the electrolyte in the hydrogel is less than 0.001% by weight, the impedance becomes high, and the hydrogel may not be suitable for conductive applications. On the other hand, if the content of the electrolyte in the hydrogel is too large, it becomes difficult to dissolve the electrolyte in the hydrogel, and crystals may precipitate inside the gel or the dissolution of other components may be inhibited. .. In addition, the conductivity reaches a plateau, and further addition cannot be said to be beneficial from the viewpoint of imparting conductivity.

The above electrolyte may be used for purposes other than imparting conductivity to the hydrogel. For example, an acid salt, a basic salt, or a polyfunctional salt may be added for the purpose of adjusting the pH of the hydrogel. Further, the above electrolyte may be added for the purpose of improving the moisturizing performance of the hydrogel and imparting antibacterial properties.

(Other additives)
Hydrogels include preservatives, bactericides, rust inhibitors, antioxidants, stabilizers, fragrances, surfactants, colorants, anti-inflammatory agents, as required, as long as they do not impair the effects of the present invention. Other medicinal ingredients such as vitamins and whitening agents may be added as appropriate. Any of these additives may be used alone, or two or more thereof may be used in combination. Further, these additives can be used in the range of 0.01 to 10% by weight based on 100% by weight of the total amount of the hydrogel.

(Manufacturing method of hydrogel)
In the hydrogel, when the polymer matrix is composed of a monofunctional monomer and a crosslinkable monomer, the components constituting the polymer matrix and the plasticizer are uniformly mixed and dissolved in water. It can be easily produced by a production method in which a monofunctional monomer and a crosslinkable monomer in the compounding solution are copolymerized with each other. The compounding solution may contain the above-mentioned water-soluble polymer, electrolyte, and / or various additives, if necessary.

Alternatively, water and a plasticizer, and, if necessary, the above-mentioned water-soluble polymer and electrolyte, are added to the polymer matrix formed by polymerizing the monofunctional monomer and the crosslinkable monomer in advance. And / or can also be produced by a production method impregnated with various additives.

The polymerization of the monofunctional monomer and the crosslinkable monomer is preferably carried out in the presence of a polymerization initiator. For example, it is preferable that the above-mentioned compounding solution contains a polymerization initiator. The polymerization initiator is not particularly limited, and examples thereof include a thermal polymerization initiator and a photopolymerization initiator.

The thermal polymerization initiator is not particularly limited as long as it is cleaved by heat to generate radicals, and is, for example, an organic peroxide such as benzoyl peroxide; azobiscyanovaleric acid, azobisisobutyronitrile, etc. Examples include azo polymerization initiators such as azobisamidinopropane dihydrochloride; persulfates such as potassium persulfate and ammonium persulfate. Any of these thermal polymerization initiators may be used alone, or two or more thereof may be used in combination. In addition, if necessary, a redox initiator composed of a reducing agent such as ferrous sulfate or pyrosulfate and a peroxide such as hydrogen peroxide, sodium thiosulfate, or peroxodisulfate is used in combination with a thermal polymerization initiator. You may.

The photopolymerization initiator is not particularly limited as long as it is cleaved by ultraviolet rays or visible light to generate radicals, and is, for example, 2,2'-azobis-N- (2-hydroxyethyl) propionamide or the like. Azo-based polymerization initiators such as 2,2'-azobis (1-imino-1-pyrrolidino-2-methylpropane) dihydrochloride, α-hydroxyketone, α-aminoketone, benzylmethylketal, bisacylphosphine oxide, metallocene More specifically, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-propan-1-one (product name: IRGACURE (registered trademark) 2959, BASF Japan Co., Ltd.), 2-Hydroxy-2-methyl-1-phenyl-propan-1-one (product name: Darocur® 1173, BASF Japan Co., Ltd.), 1-hydroxy-cyclohexyl-phenyl-ketone (manufactured by BASF Japan) Product name: IRGACURE (registered trademark) 184, manufactured by BASF Japan Co., Ltd., 2-Methyl-1-[(methylthio) phenyl] -2-morpholinopropan-1-one (Product name: IRGACURE (registered trademark) 907, BASF (Manufactured by Japan), 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butane-1-one (product name: IRGACURE (registered trademark) 369, manufactured by BASF Japan) and the like. Any of these photopolymerization initiators may be used alone, or two or more thereof may be used in combination.

The amount of the polymerization initiator used is preferably 0.01 to 1.0% by weight, preferably 0.05 to 0% by weight, based on 100% by weight of the total amount of the obtained hydrogel (the total amount of the compounding solution). More preferably, it is 5% by weight. When the amount of the polymerization initiator used is 0.01% by weight or more with respect to 100% by weight of the total amount of the obtained hydrogel (the total amount of the above-mentioned compounding solution), the polymerization reaction proceeds sufficiently and the obtained hydrogel The amount of the monofunctional monomer and the crosslinkable monomer remaining therein can be reduced. Further, when the amount of the polymerization initiator used is 1.0% by weight or less with respect to 100% by weight of the total amount of the obtained hydrogel (the total amount of the above-mentioned compounding solution), the polymerization initiation remaining in the obtained hydrogel It is possible to prevent discoloration (yellowing) and odor caused by the agent.

The method for polymerizing the monofunctional monomer and the crosslinkable monomer is not particularly limited, and for example, heating a mixture (blending solution) containing the monofunctional monomer and the crosslinkable monomer is performed. Examples thereof include light irradiation and a method of performing radiation irradiation. Specifically, a method in which a thermal polymerization initiator is contained in the mixture as a polymerization initiator and the monofunctional monomer and the crosslinkable monomer in the mixture are polymerized by heating; the polymerization is initiated in the mixture. A method in which a photopolymerization initiator is contained as an agent and the monofunctional monomer and the crosslinkable monomer in the mixture are polymerized by light irradiation (ultraviolet or visible light irradiation); the above mixture is heated as a polymerization initiator. A method of polymerizing a monofunctional monomer and a crosslinkable monomer in the mixture by containing a polymerization initiator and a photopolymerization initiator and simultaneously performing light irradiation and heating; an electron beam is added to the mixture. A method of polymerizing the monofunctional monomer and the crosslinkable monomer in the mixture by irradiating with radiation such as gamma rays or gamma rays can be mentioned. When a redox initiator is used in combination as the thermal polymerization initiator, the reaction can be carried out without heating, but the redox initiator is used in combination in order to reduce the residual monomer or shorten the reaction time. Even in this case, it is preferable to perform heating. Further, as described above, it is possible to irradiate the mixture with radiation to polymerize the monofunctional monomer and the crosslinkable monomer in the mixture, but it is a special facility for irradiation. Therefore, as a method for polymerizing the monofunctional monomer and the crosslinkable monomer in the mixture, a method of heating or irradiating the mixture with light is preferable, and a gel having stable physical properties can be obtained. From the viewpoint that the above mixture can be irradiated with light, a method of irradiating the mixture with light is more preferable.

When the above mixture contains a photopolymerization initiator and is polymerized by ultraviolet irradiation, the integrated irradiation amount of ultraviolet rays ^{is preferably 1000 mJ / cm 2} or more.

When the adhesive gel layer 30 made of hydrogel is formed, the components used for producing the hydrogel (for example, monofunctional monomer, crosslinkable monomer, plasticizer, water, water-soluble polymer, electrolyte). , Other additives) relative to the total weight (or the weight of the above-mentioned compounding solution), components other than the monofunctional monomer and the crosslinkable monomer (for example, plasticizer, water, water-soluble polymer, electrolyte, etc.) The amount of the additive) used is equal to the content of the components other than the monofunctional monomer and the crosslinkable monomer in the hydrogel. The amount of the monofunctional monomer and the crosslinkable monomer used with respect to the total weight of the components used in the production of the hydrogel (or the weight of the above-mentioned compounding solution) is the amount of the monofunctional monomer and the crosslinkable monomer in the hydrogel. Equal to the content of the sex monomer. For example, the content of the monofunctional monomer in the above-mentioned compounding solution is equal to the content of the structural unit derived from the monofunctional monomer in the hydrogel. Further, the content of the crosslinkable monomer in the above-mentioned compounding solution is equal to the content of the structural unit derived from the crosslinkable monomer in the hydrogel. Further, the total content of the monofunctional monomer and the crosslinkable monomer in the compounding solution is equal to the content of the polymer matrix in the hydrogel.

Next, another embodiment of the electrode pad according to the present invention will be described. FIG. 3 is a cross-sectional view of an electrode pad according to another embodiment. As shown in FIG. 3, the electrode pad 1B of the present embodiment has the surface material 10 and the conductive layer 20 laminated in a region excluding the peripheral portion of the surface material 10, similarly to the electrode pads 1A of FIGS. 1 and 2. And the adhesive gel layers 30 and 31 laminated on the entire surface of the surface material 10 while covering the conductive layer 20.

In the electrode pad 1A of FIGS. 1 and 2, the adhesive gel layer 30 having the same composition in the outer peripheral portion and the other portion is provided on the entire surface of the surface material 10, but the electrode pad 1B of FIG. 3 is provided. The adhesive gel layer 30 made of a highly water-containing adhesive gel containing 10 to 60% by weight of water is provided on the outer peripheral portion, and the portion other than the outer peripheral portion is adhesive having a composition different from that of the adhesive gel layer 30. It is composed of a gel layer 31. By forming at least the outer peripheral portion of the highly water-containing adhesive gel, the swelling of the adhesive gel layer 30 is suppressed when a chemical solution such as physiological saline or blood or the like comes into contact with the periphery of the electrode pad 1B, and the electrode pad 1B becomes The risk of peeling can be reduced. The width of the "outer peripheral portion" on which the adhesive gel layer 30 is provided may be the same as or different from the width of the "peripheral portion" of the surface material 10 on which the conductive layer 20 is not provided.

The adhesive gel layer 31 having a composition different from that of the adhesive gel layer 30 may contain the same components as the adhesive gel layer 30 in the electrode pads 1A of FIGS. 1 and 2. However, the content of each component is not limited to the above range and can be changed as appropriate. Further, the adhesive gel layer 31 may contain a component not contained in the adhesive gel layer 30 in the electrode pads 1A of FIGS. 1 and 2 as long as the effect of the present invention is not impaired. An example of this is polyhydric alcohols.

Examples of polyhydric alcohols include diols such as ethylene glycol, propylene glycol and butanediol, polyhydric alcohols such as glycerin, pentaerythritol and sorbitol, polyhydric alcohol condensates such as polyethylene glycol, polypropylene glycol and polyglycerin, and poly. Polyhydric alcohol variants such as oxyethylene glycerin can be used. These polyhydric alcohols can be used alone or in combination of two or more.

Among these polyhydric alcohols, it is preferable to use a liquid polyhydric alcohol in a temperature range in which the electrode pad 1B is actually used (for example, around 20 ° C. when used indoors). Examples of such preferable polyhydric alcohols include ethylene glycol, propylene glycol, polyethylene glycol, polyglycerin, and glycerin.

When a polyhydric alcohol is used, its content is preferably 150 to 350 parts by weight, more preferably 200 to 300 parts by weight, based on 100 parts by weight of the monomer constituting the polymer matrix. .. When the amount of the polyhydric alcohol added is 150 to 350 parts by weight, the change in physical properties due to drying of the obtained gel is small and high adhesive strength can be obtained, which is preferable.

Other configurations of the electrode pad 1B conform to the embodiment of the electrode pad 1A.

In the embodiments of FIGS. 1 to 3, the electrode pad used as the counter electrode of the electric knife has been described, but in addition to this, the present invention is used for an electrocardiogram measurement electrode, a low frequency therapy device electrode, and other bioelectrodes. Electrode pads can be used.

Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples, but the present invention is not limited to these Examples.

(Example 1)
15 parts by weight of acrylamide (abbreviated as "AAM", manufactured by Mitsubishi Chemical Co., Ltd.), 15 parts by weight of diacetone acrylamide (abbreviated as "DAAM", manufactured by Nippon Kasei Co., Ltd.), and N, N'-methylenebisacrylamide as a crosslinkable monomer. 0.045 parts by weight (abbreviation "MBAA", manufactured by MRC Unitech), 0.1 part by weight of sodium citrate (abbreviation "SB", manufactured by Wako Junyaku Co., Ltd.) as an antiseptic, and the following formula (1) as a plasticizer. ) Shown in polyoxyethylene methyl glucoside (methyl glyces-20, model number "MG-20E", manufactured by Nichiyu Co., Ltd., n (= a + b + c + d) in formula (1) is 20) 27.2 parts by weight and ion-exchanged water 40. .805 parts by weight, 1.00 parts by weight of citric acid as an electrolyte, 0.70 parts by weight of sodium citrate, 1- [4- (2-hydroxyethoxy) -phenyl] -2- as a photopolymerization initiator Hydroxy-2-methyl-1-propane-1-one (product name "IRGACURE (registered trademark) 2959", manufactured by BASF Japan, Inc.) was mixed with 0.15 parts by weight and dissolved by stirring to obtain a compounded solution.

Next, the obtained monomer compounding solution was spread on a silicone-coated PET film so as to have a predetermined thickness, and ^{ultraviolet rays having an energy amount of 3000 mJ / cm 2} were applied to the monomer compounding solution using a metal halide lamp. By irradiating, the above-mentioned compounding solution was polymerized to form a sheet-like adhesive gel layer having a thickness of 0.5 mm.

The prepared adhesive gel layer, a conductive layer (a laminate of 9 μm of aluminum foil and 50 μm of PET film as a reinforcing material), and a surface material to which an adhesive is applied according to the conductive layer (PE film on polypropylene non-woven fabric). It was laminated, and an acrylic adhesive was used as the adhesive), and punched into a predetermined shape to obtain an electrode pad of a predetermined size and shape. The conductive layer is laminated on the surface material in a region other than the width of 9 mm.

(Example 2)
An electrode pad was manufactured in the same manner as in Example 1 except that the adhesive gel layer was formed so that the thickness deviation was different.

(Examples 3 and 4)
An electrode pad was manufactured in the same manner as in Example 1 except that the amount of water and the amount of plasticizer in the adhesive gel layer were changed as shown in Table 1 to form the adhesive gel layer so that the thickness deviation was different. ..

(Example 5)
Instead of MG-20E, as a plasticizer, polyoxyethylene methylglucoside (methylgluces-10, model number "MG-10E", manufactured by NOF CORPORATION, n (= a + b + c + d) in formula (1) is 10) 27.2 weight An electrode pad was manufactured in the same manner as in Example 1 above, except that the parts were blended to form an adhesive gel layer so that the thickness deviation was different.

(Example 6)
In the same manner as in Example 1 above, 27.2 parts by weight of sucrose (manufactured by Kanto Chemical Co., Inc.) was blended as a plasticizer instead of MG-20E to form an adhesive gel layer so that the thickness deviation was different. An electrode pad was manufactured.

(Example 7)
Using a stirring / mixing container, first, 18 parts by weight of acrylamide as a polymerizable monomer, 0.032 parts by weight of methylenebisacrylamide as a crosslinkable monomer, and 16.41 parts by weight of ion-exchanged water were mixed. After stirring and uniformly dissolving the mixture, 60.678 parts by weight of glycerin was added as a plasticizing agent, and the mixture was stirred until uniform as described above. Next, 2.0 parts by weight of a 20% aqueous solution of polyacrylic acid was added, and the mixture was stirred until uniform in the same manner as described above. In addition, add 0.5 parts by weight of sodium chloride as an electrolyte and 2.38 parts by weight of citric acid, Na citrate, Na benzoate, ethylenediaminetetraacetic acid, and a photoinitiator as additives, and stir until completely dissolved. did. Then, the mixture was stirred for several minutes to obtain a transparent compounding solution.

Next, the obtained monomer compounding solution was spread on a silicone-coated PET film so as to have a predetermined thickness, and ^{ultraviolet rays having an energy amount of 3000 mJ / cm 2} were applied to the monomer compounding solution using a metal halide lamp. By irradiating, the above-mentioned compounding solution was polymerized to form a sheet-like adhesive gel layer having a thickness of 0.5 mm.

An electrode pad was manufactured in the same manner as in Example 1 except that the obtained adhesive gel layer was used.

(Example 8)
The above-mentioned embodiment except that the adhesive gel layer of Example 7 was laminated on the region where the conductive layer was laminated, and the adhesive gel layer of Example 1 was laminated on the peripheral edge of the surface material on which the conductive layer was not laminated. An electrode pad was manufactured in the same manner as in Example 1.

(Comparative Examples 1 and 2)
An electrode pad was manufactured in the same manner as in Example 1 except that the amount of water and the amount of plasticizer in the adhesive gel layer were changed as shown in Table 1 and the thickness deviation was made different.

(Comparative Example 3)
An electrode pad having an adhesive gel layer made of a different gel type in the outer peripheral portion and the other portion was produced in the same manner as in Example 8 except that the thickness deviation was made different.

(Comparative Example 4)
An electrode pad was manufactured in the same manner as in Example 7, except that an adhesive gel layer was not provided on the peripheral edge of the surface material, and an adhesive layer made of an acrylic acid ester resin was provided instead.

(Comparative Example 5)
As an electrode pad, "NE-SP" manufactured by Sekisui Plastics Co., Ltd. was prepared. The plan view of this electrode pad is equivalent to that shown in FIG. 1, and the cross section has the structure shown in FIG.

(Comparative Example 6)
As an electrode pad, "Thermo Gard (registered trademark) 51-7310" manufactured by CONMED was prepared. This electrode pad has a recess in the center of the surface material, and the recess has a structure in which a conductive layer and an adhesive gel layer are laminated, and an adhesive layer is provided on the periphery of the surface material, which is a peelable cover film. It has a covered structure.

(Comparative Example 7)
As an electrode pad, "NESSY (registered trademark) Omega Plate" manufactured by ERBE was prepared. This electrode pad has a structure in which an adhesive layer is provided on the surface material, a conductive layer and an adhesive gel layer are sequentially laminated in a region excluding the peripheral portion on the surface material, and covered with a peelable cover film. ..

In the electrode pads of Examples 1 to 8 and Comparative Examples 1 to 7, the thickness (mm) of the electrode pad in the portion where the conductive layer is present, the thickness (mm) of the electrode pad in the peripheral portion of the surface material, and the thickness deviation (mm). The values of are summarized in Table 1. Further, when the swelling rate (%) of the outer peripheral portion of the adhesive gel layer is exposed to an environment of 40 ° C. and 90% RH for 1 hour, and when exposed to an environment of 40 ° C. and 90% RH for 12 hours. It was measured. The measurement results are shown in Tables 1 and 2. In Tables 1 and 2, those having a swelling rate of 130% or less when exposed for 1 hour are indicated by 〇, and those exceeding 130% are indicated by ×. In addition, those with a swelling rate of 130% or less after exposure for 12 hours are ⊚, those with a swelling rate of more than 130% and 170% or less are 〇, those with a swelling rate of more than 170% and 200% or less are △, and those exceeding 200%. Is written as x.

(Measurement method of swelling rate)
The hydrogels (gel sheets) obtained in Examples 1 to 8 and Comparative Examples 1 and 3 are each cut into a size of 20 mm in width × 120 mm in length, and then the PET film (top film) on one side is peeled off. It was. A test piece was prepared by lining this surface with synthetic paper having a thickness of 80 μm (for example, “Peach Coated Paper SE80” manufactured by Nisshinbo Paper Products Co., Ltd. or “FGS80” manufactured by Yupo Corporation). The PET film (base film) on the other side of the hydrogel in this test piece was peeled off, and then the weight was measured to obtain the weight (W0) before exposure to a high humidity environment. Then, it was allowed to stand in a constant temperature bath at 40 ° C. and a relative humidity of 90% for 1 hour. After 1 hour, the weight of the hydrogel was measured and used as the weight (W1) after exposure to a high humidity environment. Then, the swelling rate was calculated from the following formula. The high humidity environment means 40 ° C. and 90% relative humidity.
Swelling rate (%) = W1 / W0 × 100
W0 = weight of hydrogel before exposure to high humidity environment (g)
W1 = Weight of hydrogel after exposure to high humidity environment (g)

<Skin irritation evaluation>
Each of the obtained electrode pads was attached to the thighs of 5 subjects, left to stand for 60 minutes, and then peeled off. At that time, 1 point was given when pain was felt, 3 points were given when slightly pain was felt, and 5 points were given when almost no pain was felt. Was set to Δ, and 10 points or more was set to 〇. The evaluation results are shown in Tables 1 and 2.

<Skin adhesive strength>
The adhesive strength to the skin was measured for each of the obtained electrode pads. The outer peripheral portion of the electrode pad was cut out with a width of 9 mm, attached to the inner portion of the forearm, and the adhesive strength at 180 ° peeling was measured (unit: N / 9 mm). The results are shown in Tables 1 and 2.

<Evaluation of pressure on the skin>
Each of the obtained electrode pads was attached to the thighs of five subjects, and the feeling of pressure on the skin when the subjects were in a lying position for 60 minutes was examined. 1 point when feeling pressure, 3 points when feeling a little pressure, 5 points when almost no pressure is felt, and the total score of 5 people is 10 points or less × 11 to 19 points △, 20 Scores above the point were marked as 〇. The evaluation results are shown in Tables 1 and 2.

As shown in Table 1, the electrode pads of Examples 1 to 8 were controlled so that the thickness deviation was 0.4 mm or less and the water content of the outer peripheral portion of the adhesive gel layer was within the range of 10 to 60% by weight. In each case, the swelling rate of the adhesive gel layer was small. In addition, since the adhesive gel layer provided on the entire surface of the surface material comes into contact with the skin, it is less irritating to the skin and is superior. Further, in the electrode pads of Examples 1 to 8, the adhesive gel layer was provided on the entire surface of the surface material, and the thickness deviation was 0.4 mm or less, so that the feeling of pressure on the skin was small.

Since the electrode pads of Examples 1 to 7 have the same gel type in the outer peripheral portion of the adhesive gel layer and the portion on the conductive layer, the stability over time is high. On the other hand, in the electrode pad of Example 8, since the composition of the gel type is different between the outer peripheral portion and the portion on the conductive layer, the plasticizer in the gel may be mixed and the stability may be lost.

The electrode pad of Comparative Example 1 had a large swelling rate and was unsuitable because the amount of water in the outer peripheral portion of the adhesive gel layer was small. In addition, since the thickness deviation was large, the feeling of pressure on the skin was large. Further, in the electrode pad of Comparative Example 2, since the water content of the adhesive gel layer was too large, the shape retention of the gel was poor, and it was not possible to produce an electrode pad that could be attached to the skin.

Since the electrode pad of Comparative Example 3 had a large thickness deviation, the feeling of pressure on the skin was large and could not be achieved. The electrode pads of Comparative Examples 4 to 5 had higher adhesive strength at the peripheral portion as compared with Examples, and were slightly irritating to the skin. The electrode pads of Comparative Examples 6 to 7 had a very high adhesive force at the peripheral portion and were highly irritating to the skin. Further, since the electrode pads of Comparative Examples 4 to 7 have an adhesive on the peripheral edge, they may be mixed with each other when they come into contact with the plasticizer in the gel, resulting in lack of stability.

1A Electrode pad 1B Electrode pad 10 Surface material 101 Tongue piece 102 Peeling convex piece 20 Conductive layer 20a Resin film 20b Electrode element 201 Connection part 30 Adhesive gel layer 31 Adhesive gel layer 40 Cover film 400 Electrode pad 401 Surface material 402 Adhesive layer 403 Conductive layer 403a Resin film 403b Electrode element 404 Adhesive gel layer 405 Cover film h Thickness L Lead wire S1 Conductive layer area S2 Surface material area

Claims (8)

An electrode pad used by being attached to the surface of a living body to pass an electric current through the living body.
Surface material and
A conductive layer laminated in a region excluding the peripheral portion on the surface material, and
It has an adhesive gel layer laminated on the entire surface of the surface material while covering the conductive layer.
The thickness deviation is 0.4 mm or less,
The electrode pad in which at least the outer peripheral portion of the adhesive gel layer is made of a highly water-containing adhesive gel containing 10 to 60% by weight of water. The electrode pad according to claim 1, wherein the adhesive gel layer has the same composition in the outer peripheral portion and other portions. The electrode pad according to claim 1 or 2, wherein the highly water-containing adhesive gel has a swelling rate of 130% or less when exposed to an environment of 40 ° C. and 90% RH for 1 hour. The electrode pad according to any one of claims 1 to 3, wherein the highly water-containing adhesive gel has a swelling rate of 200% or less when exposed to an environment of 40 ° C. and 90% RH for 12 hours. The high water content adhesive gel is a hydrogel containing a polymer matrix, water and a plasticizer, and the plasticizer is a polyoxyalkylene alkyl ether and / or a sugar according to any one of claims 1 to 4. The electrode pad described. The polyoxyalkylene alkyl ether is at least one selected from the group consisting of polyoxyethylene methyl glucoside and polyoxyethylene alkyl ether, and the sugar is at least selected from the group consisting of monosaccharides, disaccharides and polysaccharides. The electrode pad according to claim 5, which is a kind. The electrode pad according to claim 5 or 6, wherein the content of the plasticizer is 10 to 60% by weight based on 100% by weight of the total amount of the hydrogel. The electrode pad according to any one of claims 1 to 7, which is used as a counter electrode of an electric knife in an electric knife device.

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