JP2806594B2 - Medical conductive adhesive gel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an electrode for potential pickup (for example, an electrode for electromyogram, an electrode for electroencephalogram measurement, an electrode for electrocardiogram, an electrode for electrooculogram measurement, etc.) and a current passive. Conductivity used for medical and electrical observations to connect the living body electrode (for example, a return electrode for an electric scalpel, an electrode for a low frequency treatment device, an electrode for iontophoresis, etc.) and a living body, or a living body observation of animals and plants. It relates to an adhesive gel.

(Prior Art) Numerous conductive adhesives or conductive adhesive gels have been devised for the purpose of electrically and physically connecting a potential pickup electrode and a current passive electrode to a living body. A feature common to many of these already proposed technologies is that a polymer electrolyte is used as a means for expressing conductivity. An example of such means is described as a carboxylate (for example, see
36939, JP-B-57-28505), quaternary ammonium salts (for example, JP-A-52-95895, JP-A-62-133935, JP-A-62-133935)
-3596391, JP-A-62-270135, JP-A-62-292140, JP-A-63-43646), sulfonate (for example, JP-A-55-8
1635, JP-A-58-135506, JP-A-59-125545) and phosphates (for example, JP-A-61-85925). Since these polymer electrolytes have very hard and brittle physical properties in a dry state and have very low conductivity, glycerin must be used to impart conductivity and tackiness to these polymer electrolytes. It is necessary to plasticize these robust polymers by using polyhydric alcohols having very high hydrophilicity represented by, for example, and in a large amount. Gels composed of such means have a low gel strength because they contain a large amount of plasticizer and require support materials such as nonwoven fabrics, and these gels absorb and desorb due to storage environment conditions, especially changes in humidity. Therefore, there is a drawback that the physical properties of the gel greatly change with this, so that long-term deterioration of physical properties is inevitable, and expensive packaging has to be used to prevent this. Furthermore, a fatal defect when these polyelectrolytes are used for such a purpose is that the gel swells due to moisture absorption when used under high humidity and absorption of sweat secreted from the skin. The worst case is that the electrodes can easily fall off the skin under their own weight. This disadvantage is an inevitable problem when the polymer electrolyte is used for such a purpose. Since the polymer disclosed in JP-A-56-36940 is composed of a nonionic polymer, it is thought that the disadvantage that the adhesive gel swells remarkably can be avoided. As can be understood, the conductivity and adhesiveness of the gel formed by such a technique are extremely low, and especially when the potential pickup electrode and the living body are connected by this gel, it is necessary to avoid being affected by the hum noise of the commercial power supply. It is highly anticipated that the goal of physically connecting a living body and an electrode with sufficient strength will not be achieved because of its low adhesiveness.

What has recently attracted the interest of the inventors is disclosed in Japanese Patent Application Laid-Open No. 62-139628.
Is an ionic conductive gel disclosed in US Pat. This gel is a product in which an alkali ion compound is contained in hydrophilic polyether urethane, and is a nonionic hydrophilic gel having relatively good conductivity and strong adhesiveness, based on a design concept that has never existed before. It was noted that it is composed of
However, gels made from this technique have drawbacks derived from the nature of the polymer synthesis and the respective polymer structure.

A disadvantage in polymer synthesis is that the presence of moisture is not allowed during the gel formation reaction. The gel-forming reaction referred to herein means a reaction between a polyether polyol prepolymer and a polyisocyanate prepolymer. Since the conductivity of the adhesive gel made of this polyether polyurethane gel is considerably inferior to the gel using the above-mentioned polymer electrolyte, when used for the purpose of connecting the potential pickup electrode and the living body,
It is necessary to further improve the conductivity. The simplest way to achieve this object is to include a solvent having a high dielectric constant, such as water or a (poly) alcohol, in the gel. These solvents are allowed to coexist during the gel formation reaction. This results in the generation of air bubbles and a decrease in the physical properties of the pressure-sensitive adhesive, which is not a preferable method. Therefore, in order to improve the dielectric properties by using these solvents, it is necessary to post-add by some method after the gel formation reaction, and as a result, mass production efficiency is significantly reduced. Will. Also, in the gel forming reaction step and the raw material storage step, strict control is required to avoid the absorption of the raw material, and the cost increase accompanying this is unavoidable.

A disadvantage derived from the polymer structure is that when a gel made of this technique is applied to a living body, the adhesive force is reduced in a relatively short time. This tendency is remarkable especially when worn on the skin of the human body with some sweating. This is probably due to the low hydrophilicity of the polymer. In other words, since the gel has low hydrophilicity, the perspiration rate of sweat secreted from the skin is higher than the rate at which the gel absorbs the sweat, so that a sweat reservoir layer is formed at the interface between the gel and the skin. It is conceivable that the body spreads over the entire surface of the gel, and eventually the gel falls off. This is a fatal drawback when a polyurethane made from polyether polyol is used for such a purpose. This is because, when further increasing the hydrophilicity, there is no effective means other than increasing the proportion of the ethylene oxide units in the polyether polyol molecule as the raw material. As one of ordinary skill in the art can easily guess, increasing the proportion of ethylene oxide in the polyether polyol molecule will increase the crystallization of the polyether polyol and the resulting gel. It is expected that the handling in the process is deteriorated, and that the conductivity is lowered.

(Object of the Invention) The object of the present invention is to solve the problem that could not be solved by the techniques proposed so far, namely, to ensure that the skin and the electrode are electrically and physically connected even when used under high humidity. It is an object of the present invention to provide a medical conductive adhesive gel which is connected and maintains this connection for a long period of time, and does not fall off even if there is slight sweat from a human body and maintains strong adhesiveness.

(Means for Achieving the Object) As a means for achieving the above object, the medical conductive adhesive gel of the present invention has a carbon number of 2 to 18 as an adhesive component.
Having an alkyl group of 40 mol% or more, a dissociable functional group as an ion carrier of 2 to 24 mol, and a repeating alkylene oxide unit of 2 or more, having a long alkylene oxide chain in a side chain. It is characterized by using a polymer to be used.

It is possible to provide sufficient tackiness by controlling the type of plasticizer and the amount of plasticizer only with a polymer not contained in the alkylene oxide long-chain molecule, but sufficient conductivity can be obtained with this system alone. It is difficult. Therefore, when this polymer is used as a base polymer of a pressure-sensitive adhesive, it is necessary to contain an appropriate low molecular electrolyte. As a result, a gel having tackiness and conductivity is obtained. However, when the potential pickup electrode and the living body are electrically connected, it is necessary to further improve the conductivity in order to avoid hum noise of a commercial power supply. As a method of improving conductivity, a method of increasing the content of a dissociable functional group as an ion carrier,
There is a method of adding a small amount of water to the gel. In the former method, the purpose of improving the conductivity can be achieved, but increasing the amount of the dissociable functional group in the base polymer results in an increase in the glass transition temperature of the polymer. In order to obtain the property, a large amount of a plasticizer is required, which is the same as the conventional technique of using a polyelectrolyte as a base polymer. The disadvantages of the gel are as described above. Also, when the conductivity is improved by the latter method, it will show good conductivity immediately after production, but if it is stored for a long time under low humidity, the water added during production will volatilize. Therefore, in order to avoid this volatilization, it is necessary to use expensive packaging as described above, so this method cannot be said to be a desirable method.

The present inventors have conducted intensive studies on this point, and have found that the above-mentioned alkyl group having 2 to 18 carbon atoms has 40 mol% or more and a dissociable functional group as an ion carrier has 2 to 24 mol%.
As a new ion carrier, a polymer obtained by introducing a long chain of alkylene oxide having two or more alkylene oxides as a new ion carrier into a side chain of a polymer having the same as a base polymer. By dissolving and cross-linking by well-known means, so that adhesiveness never before existed,
It has been found that a medical conductive adhesive gel selected for its conductivity and cohesion can be obtained.

Next, each raw material constituting the medical conductive adhesive gel will be described in detail. The structure of the base polymer, when viewed in monomer units, is basically composed of the following three units. That is, it is composed of three components: an alkyl acrylate unit (A unit) having an alkyl group having 2 to 18 carbon atoms, an ion carrier unit (B unit), and another unit (C unit).

The purpose of introducing the A unit is to lower the glass transition temperature of the base polymer to impart tackiness, and to control the hydrophilicity. The simplest and most practical method for introducing this unit is to copolymerize an alkyl ester of an α, β-unsaturated carboxylic acid having an alkyl group having 1 to 18 carbon atoms. Monomers suitable for this purpose include, but are not limited to, ethyl acrylate, acrylic acid-n-
Butyl, t-butyl acrylate, 2-ethylhexyl acrylate, butyl methacrylate, methacrylic acid-n
-Lauryl, tridecyl methacrylate, dibutyl fumarate, monobutyl itaconate, dibutyl itaconate and the like. The proportion of the A unit in the base polymer is at least 40 mol% if the unit is an alkyl ester of an α, β-unsaturated carboxylic acid, but the practical range is 60 to 90 mol%. If the amount is less than 60 mol%, it is difficult to obtain sufficient tackiness, and if it exceeds 90 mol%, it tends to be difficult to obtain sufficient hydrophilicity and conductivity.

The purpose of introducing the B unit is to introduce the ion carrier into the base polymer and to control the hydrophilicity in combination with the ratio of the A unit.
As can be seen from the above description, the B unit is composed of a monomer unit having a dissociative functional group and a monomer unit for introducing an alkylene oxide long chain having a repetition number of 2 or more into the base polymer main chain. .

As a means for introducing a dissociable functional group, when the base polymer is viewed in monomer units, it can be obtained by copolymerizing the following monomers, which are not limited thereto. α, β-unsaturated carboxylate (eg, acrylate, methacrylate, itaconic acid salt, etc.), vinyl monomer having sulfonate (eg, allyl sulfonate, methacryl sulfonate, vinyl sulfonate) , 2-acrylamido-2-methylpropanesulfonate, etc.), a monomer having a phosphate or a phosphite (eg, 2-acryloyloxyethyl phosphate), and a vinyl monomer having a quaternary ammonium salt (eg, , Methacryloyloxyethyltrimethylammonium chloride, methacrylamidopropyltrimethylammonium chloride, etc.)
Etc. are monomers for introducing a dissociative functional group,
It is not necessary for the copolymer to be already in a salt form at the time of copolymerization, and it is needless to say that it can be introduced by partial neutralization or complete neutralization after polymerization of the base polymer. Further, these dissociative functional groups are not limited to one kind, and may be composed of a monomer unit having a plurality of kinds of dissociative functional groups. The proportion of this dissociable functional group in the base polymer molecule is
It is 2 to 24 mol%, and practically, it is in the range of 5 to 15 mol%. If it is less than 5 mol%, it is difficult to obtain sufficient hydrophilicity and cohesive strength, and if it exceeds 15 mol%, the base polymer tends to be too hard to obtain a sufficient adhesive force.

Means for introducing a long alkylene oxide chain into the base polymer side chain include a method using a polymer reaction and a method for copolymerizing a vinyl monomer having an alkylene oxide. The method seems to be better. Non-limiting structures of monomers suitable for this purpose are shown in the following structural formula (I).

Here, R ₁ is either H or CH ₃ , and R ₂ is H, CH ₃ ,
It is an unsubstituted alkyl group such as CH ₂ CH ₃ or a substituted alkyl group. (EO) represents an ethylene oxide unit, and m is ≧
Number of 0. (AO) represents an alkylene oxide unit, and n is the number of repetitions of the alkylene oxide unit, and n ≧ 2.
Is an integer greater than or equal to. The alkylene oxide chains suitable for the present invention include, but are not limited to, those shown in structural formula (II).

(CH ₂ O), (CH ₂ CH ₂ O) (CH ₂ CH (CH ₃ ) O), (CH ₂ CH ₂ CH ₂ CH ₂ O) (II) (AO) represented by the structural formula (I) ) Is the structural formula (II)
May be a single body or a random body or a block body of a plurality of types of alkylene oxide units. However, from the viewpoint of hydrophilicity and conductivity, (AO) represented by the structural formula (I) It is preferable that a part or the whole is an ethylene oxide unit, and the number of m is preferably 4 or more. When the number is less than 4, there is a tendency that it is difficult to obtain sufficient hydrophilicity and conductivity. The monomer unit as a means for introducing the alkylene oxide long chain includes:
It is not limited to one kind, and a plurality of monomers can be used in combination. Non-limiting examples of the monomer corresponding to the structural formula (I) include polypropylene glycol monomethacrylate (repeat number of propylene oxide (n = 12)), polyethylene glycol monomethacrylate (n = 7 to 9), polyethylene glycol (n
= 10) polytetramethylene glycol (n = 5) monomethacrylate, methoxypolyethylene glycol (n =
8) Allyl ether, methoxypolyethylene glycol (n = 9) methacrylate and the like. The proportion of the monomer having an alkylene oxide chain in the base polymer is difficult to show a proper range because the molecular weight of the monomer greatly varies depending on the number of repeating alkylene oxide units. Had a desirable tendency.

The purpose of introducing the C unit is to finely adjust the adhesiveness, hydrophilicity and cohesive force, and at the same time to introduce a crosslinking functional group. Non-limiting examples of monomers suitable for this purpose include vinyl acetate, acrylonitrile, acrylamide, t-butylacrylamide, diacetone acrylamide, styrene, methyl methacrylate, methacrylic acid, acrylic acid,
Itaconic acid, maleic anhydride, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, dimethylaminoethyl methacrylate, methylol acrylamide, glycidyl methacrylate, acrylic acid-2
-Methoxyethyl, ethoxyethoxyethyl acrylate, tetrahydrofurfuryl acrylate and the like. These monomers are incorporated into the base polymer by copolymerization, but can be used as a cross-linking functional group by a known technique as described above. Needless to say, for example, the possibility of obtaining a self-crosslinking base polymer, such as the combination of methacrylic acid and glycidyl methacrylate, is also mentioned. Since the proportion of the C unit in the base polymer varies depending on the required characteristics, a typical range cannot be shown.

The purpose of adding the plasticizer to the base polymer is not only to plasticize the polymer but also to promote the dissociation of the low-molecular electrolyte described below. For this reason, it is difficult to achieve this object by using only one type of plasticizer, and usually, a mixture of a plurality of plasticizers often provides favorable results in terms of various physical properties. Non-limiting examples of plasticizers that have achieved this purpose include water, ethylene glycol, propylene glycol, glycerin,
And other polyethers; polyethylene glycol derivatives such as ethylene glycol dimethyl ether, polyethylene glycol dimethyl ether and polyethylene glycol monomethyl ether; polypropylene glycol derivatives such as polypropylene glycol and poly (oxyethylene-oxypropylene) alkyl ether; and other various polyethers. (Poly) ols, carbonates such as ethylene carbonate, propylene carbonate, and glycerin carbonate; amides such as N-methylpyrrolidone, dimethylamide, and hexamethylphosphoramide;
Fatty acid esters containing an alkylene oxide chain such as polyoxyethylene alkyl phenyl ethers, polyethylene glycol fatty acid esters, polyoxyethylene glycerin fatty acid esters, and polyoxyethylene sorbite fatty acid esters. The amount of these plasticizers varies greatly depending on the purpose of use of the adhesive gel and the environment of use, but is approximately 50 to 250 parts by weight based on 100 parts by weight of the base polymer.
A suitable range is about parts by weight.

Since the base polymer in the present invention has much lower hydrophilicity than the base polymer using a polymer electrolyte found in the prior art, in order to provide sufficient conductivity, a low molecular electrolyte must be dissolved and contained. is required.
As an electrolyte for achieving this purpose, alkali metal ions represented by Li ⁺ , Na ⁺ , K ⁺
Alternatively, a quaternary ammonium ion represented by R ₄ N ⁺ (R is hydrogen or a lower alkyl group), and an anion component includes a halogen ion represented by Cl ⁻ , Br ⁻ , and I ⁻ , a thiocyanate ion, and a perchlorine. Acid ion, alkylsulfonic acid ion and the like. The electrolyte composed of a combination of the elements exemplified here is not limited to one kind, and a plurality of electrolytes can be mixed and used. The addition of these electrolytes may be dissolved in the polymerization solvent in advance, or may be added and dissolved after the polymerization. The addition amount of these electrolytes is in the range of about 0.2 to 30 parts by weight with respect to 100 parts by weight of the base polymer, but practically 1 to 10 parts are balanced in both adhesiveness and conductivity. Area. If the amount is less than 1 part, sufficient conductivity cannot be obtained. If the amount exceeds 10 parts, the base polymer tends to be hard and it is difficult to obtain sufficient tackiness.

(Function and Effect) The conductive adhesive gel for medical use according to the present invention has properties that cannot be obtained by the prior art, that is, sufficient adhesive force and cohesion without swelling even during long-term storage and long-term operation under high humidity. It maintains its power and can maintain a sufficient adhesive strength to the skin with slight sweating, and contains almost no volatile components and moisture-absorbing components. Has the characteristic that it does not fluctuate significantly.

In addition, since the viscosity of the dope at the time of production is lower than that of a gel using a conventional polymer electrolyte, the production method can be selected according to the final use purpose and the target shape such as casting, coating, impregnating a non-woven fabric, etc. The fact that there are many types of manufacturing methods is also an advantage of this technology.

(Examples) Next, the present invention will be described in more detail with reference to examples.

[Measurement method] 1. Volume resistance value (SR) An adhesive gel with a thickness of about 1 mm is punched to a diameter of 20 mm, and the upper and lower surfaces are sandwiched between stainless steel plates (SUS 304) with a thickness of about 1 mm. Assemble, apply 1kHz sine wave and measure impedance by Lissajous method. From this value and the shape of the gel, a volume resistance value is calculated. All measurements
The test was performed at 23 ° C. and 60% RH.

2. Equilibrium swelling degree (DS) An adhesive gel with a thickness of about 1 mm is punched out with a diameter of 10 mm (d1 = 10 mm) and attached to a petri dish with an inner diameter of 8 cm and a depth of 2 cm. Pour 40 ml of pure water into this dish. This is properly evaporated and placed in a 40 ° C. incubator for 20 ± 4 hours, and the diameter (d2) of the swollen gel is measured. From this, d2 / d1 is calculated, and this is 40
Degree of equilibrium swelling in water at ℃.

3. Rate of decrease in peeling force (DP) Cut a 1 mm thick adhesive gel into a 2 x 5 cm rectangle, paste one side to a bakelite plate, and release the other side
Leave for about 2 weeks in an environment of 40 ° C and 40RH%. A soft vinyl chloride film is adhered to the open surface. Hold this film in the long side direction, 180 ° from the adhesive sheet, 30cm / mi
Average the peeling force at a speed of n between 5 cm, and this is 40
Peeling force (P40) in an environment of 40 ° C and 40 ° C. The same measurement is also performed on a sample that has been left for about two weeks in an environment of 40 ° C. and 90 RH%, and this is defined as (P90).
From these two data, (P90 / P40) is calculated, and this is defined as the rate of decrease in the peeling force.

4. Moisture absorption increase rate (IA) A 1mm thick adhesive sheet is punched into 20mmφ, 40 ℃, 75R
Leave in an environment of H% for about 2 weeks and determine the moisture absorption (W75).
At this time, the sheet having the same shape is similarly left for about two weeks in an environment of 40 ° C. and 90 RH%, and the moisture absorption (W90) is obtained. These two
((W90-W75) / W75) is determined from the two data, and is defined as the rate of increase in moisture absorption.

[Adjustment of Polymer and Gel] Comparative Example 1 Raw materials were charged into a three-neck separable flask at the following ratio (parts by weight).

2-hydroxymethacrylate 43.9 parts Acrylic acid 6.1 Methanol 75.0 After purging with nitrogen, 1.4 parts of AIBN (azobisisobutyronitrile) was added as an initiator, and polymerization was carried out under reflux for 18 hours. After cooling the system to near room temperature, 10.11 parts of 5N-sodium hydroxide solution was added to control the degree of neutralization of acrylic acid to 0.5. The polymerization solvent and water used for neutralization were removed by heating to pulverize the polymer.

To 10 parts of the obtained polymer, 28 parts of glycerin and 12 parts of purified water were added, and a uniform dope was obtained at 80 ° C. for 16 hours.

To 50 parts of this dope, 0.5 part of tetrafunctional polyglycerol polyglycidyl ether was added, and heating was performed at 60 ° C. for 16 hours to obtain a sticky gel.

Comparative Example 2 The charged materials are as follows.

Butyl acrylate 32 parts Acrylic acid 18 Methanol 75 AIBN 1.64 A uniform dope is obtained by the same operation as in Comparative Example 1.

To 50 parts of the dope, 0.42 part of a tetrafunctional polyglycerol polyglycidyl ether was added, and heating was performed at 60 ° C. for 16 hours to obtain a sticky gel.

Example 1 Raw materials were charged into a three-neck separable flask at the following ratio (parts by weight).

 Butyl acrylate 18.0 parts Acrylic acid 2.0 Methanol 30.0 Lithium perchlorate 1.0 AIBN 0.51 Polymerization was carried out for about 16 hours at a reflux temperature under a nitrogen stream.

The whole system was cooled to around room temperature, and 14.0 parts of polyoxyethylene nonylphenyl ether (average number of oxyethylene repeats: 7.5) and 6.0 parts of dimethoxy polyethylene glycol (molecular weight: about 300) were added and mixed as plasticizers.
About 5 parts of potassium hydroxide was added, and the neutralization degree of acrylic acid was reduced to 0.
Control to 5. After confirming that the neutralization reaction was completed and the whole solution returned to room temperature, 0.2 parts of tetrafunctional polyglycerol polyglycidyl ether was added, and a tacky gel was obtained by heating at 60 ° C. for 16 hours.

Example 2 Raw materials were charged into a three-neck separable flask at the following ratio (parts by weight).

Butyl acrylate 14.0 parts Acrylic acid 2.0 MPEGMA (n = 9) 4.0 Methanol 30.0 Lithium perchlorate 1.0 AIBN 0.51 * MPEGMA (n = 9) means methoxypolyethylene glycol (repeating number of ethylene oxide n = 9) methacrylate.

An adhesive sheet was obtained under the same operation and under the same conditions as in Example 1.

Example 3 Raw materials were charged into a three-neck separable flask at the following ratio (parts by weight).

Butyl acrylate 14.0 parts Acrylic acid 2.0 MBEGMA (n = 23) 4.0 Methanol 30.0 Lithium perchlorate 1.0 AIBN 0.51 * MPEGMA (n = 23) refers to methoxypolyethylene glycol (ethylene oxide repeating number n = 23) methacrylate.

An adhesive sheet was obtained under the same operation and under the same conditions as in Example 1.

Example 4 Raw materials were charged into a three-neck separable flask at the following ratio (parts by weight).

 Butyl acrylate 14.0 parts Acrylic acid 2.0 MPEGMA (n = 23) 4.0 Methanol 30.0 Lithium perchlorate 1.0 AIBN 0.52 Polymerization was carried out under a nitrogen stream at a dry distillation temperature for about 16 hours.

The whole system was cooled down to around room temperature, and 8.1 parts of polyoxyethylene nonyl phenyl ether (average number of repetitions of oxyethylene 7.5) as a plasticizer and glycerin carbonate 24.4
The mixture is added and mixed, and about 5 parts of 3N-potassium hydroxide is further added to control the neutralization degree of acrylic acid to 0.5. It was confirmed that the neutralization reaction was completed and the whole solution had returned to room temperature, and 0.27 parts of tetrafunctional polyglycerol polyglycidyl ether was added, and a sticky gel was obtained by heating at 60 ° C. for 16 hours.

Example 5 Raw materials were charged into a three-neck separable flask at the following ratio (parts by weight).

Butyl acrylate 14.0 parts Acrylic acid 0.4 MPEGMA (n = 23) 4.0 MOETMAC 4.0 Methanol 30.0 Lithium perchlorate 1.0 AIBN 0.52 * MOETMAC indicates methacryloyloxyethylenetomethylammonium chloride.

 Polymerization was carried out under a nitrogen stream at a distillation temperature for about 16 hours.

The whole system was cooled down to around room temperature, and 16.0 parts of polyoxyethylene nonylphenyl ether (average number of repetitions of oxyethylene: 7.5) as a plasticizer and 4.0 parts of dimethoxy polyethylene glycol (molecular weight: about 300) were added and mixed, and then 3N-
About 5 parts of potassium hydroxide was added, and the neutralization degree of acrylic acid was reduced to 0.
Control to 5. After the neutralization reaction was completed and the whole solution was returned to room temperature, 0.22 parts of tetrafunctional polyglycerol polyglycidyl ether was added, and the mixture was heated at 60 ° C. for 16 hours to have a tacky volume resistance value of 556 KΩ. Cm gel was obtained.

[Characteristic evaluation] 1. Comparison of volume resistance values Table 1 shows a comparison of volume resistance values of Examples 1, 2, and 3. This data shows the effect of introducing a long alkylene oxide chain on conductivity.

2. Comparison with Conventional Technique Next, Table 2 shows each characteristic value of Comparative Examples 1 and 2 and Example 4, and it is desired to clarify that the present invention is superior to the prior art. think.

In Table 2, the hydrophilicity of the gel according to the technology of the present invention is suppressed to be lower than that of the conventional gel, and although the conductivity is slightly worse than that of the conventional gel,
It is recognized that the improvement in the decrease in tackiness during use or storage under high humidity is sufficiently achieved.

3. Others Example 5 shows that coexistence of a carboxylate and another dissociable functional group is possible as a dissociable functional group.

As described in this specification, the means for crosslinking include:
The scope is not limited only to the reaction between the carboxylate and the water-soluble glycidyl compound shown in the examples, and any well-known means can be used.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) A61B 5/0408 A61N 1/04

Claims (1)

(57) [Claims] (1) a monomer unit having at least 40 mol% of an alkyl acrylate having an alkyl group having 2 to 18 carbon atoms, having a dissociable functional group of 2 to 24 mol%, and having at least 2 alkylene oxide repeating units; The above condition is that a polymer characterized by having an alkylene oxide long chain in the side chain is an essential condition, and further, this polymer is plasticized, and a low molecular dissociable salt is dissolved and contained to form a three-dimensional crosslinked structure. A conductive adhesive gel having sufficient strength, adheres to the human skin with sufficient strength, and has an equilibrium swelling degree in water of 40 ° C. of 3.5 or less. Adhesive gel.