JPH04357932A - Pad for electrode and electrode - Google Patents

Abstract

PURPOSE:To provide the pad for an electrode excellent in electrical conductivity, flocculatability, transparency, etc., and the electrode. CONSTITUTION:The pad for the electrode formed by reinforcing a gelatinous compd. with a sheet-like material, such as woven or knitted fabric, nonwoven fabric or net-like material and the electrode are provided. This gelatinous compsn. consists of the polymer of a monomer having a sulfonic acid group in the molecule, a polyvalent metal salt and water. This polymer holds an aq. polyvalent metal salt soln. consisting of the polyvalent metal salt and the water. The electrode is formed by laminating a conductive sheet provided with a connecting means to the outside and this pad.

Description

[Detailed description of the invention]

0001

[Industrial Application Fields] The present invention has excellent conductivity, cohesiveness, transparency, and antibacterial properties, and is suitable for adhesive electrodes, biological electrodes, electrodes for electrocardiographs, electrodes for low-frequency treatment devices, and electric scalpels. The present invention relates to electrode pads and electrodes used for counter electrode plates and the like.

0002

[Prior Art] Conventionally, gelatin (Japanese Patent Publication No. 50-2731
Natural hydrophilic polymers such as gum karaya (US Pat. No. 7, No. 7) and Karaya gum (US Pat. No. 4,125,110), and hydrophilic polymers crosslinked with a bifunctional crosslinking agent (Japanese Patent Publication No. 2-29328) are known. It is being

0003

[Problems to be Solved by the Invention] However, when natural hydrophilic polymers are used as biological adhesive materials or gels for biological electrodes, since the polymers are natural products, impurities and foreign substances may be present. Contamination is unavoidable, and as a result, the quality of the gel is unstable, the adhesiveness of the gel is inconsistent, it also has a negative effect on the electrical properties of the electrode, and furthermore, the impurities that are mixed in can cause allergic reactions on the skin of the living body. There was a problem.

Further, when a crosslinked hydrophilic polymer is used, processing after crosslinking is difficult and there are problems such as a lack of flexibility.

[0005] The present invention aims to solve the problems of the conventional technology as described above, and provides an electrode pad and an electrode for biological electrodes etc. that have excellent conductivity, transparency, etc. purpose.

[0006]

[Means for Solving the Problems] The above object is to provide an electrode pad and an electrode of the present invention, which are composed of a polymer of a monomer having a sulfonic acid group in the molecule, a polyvalent metal salt, and water. An electrode pad made by reinforcing a gel composition containing a polyvalent metal salt aqueous solution consisting of the polyvalent metal salt and water with a sheet-like material, and a conductive sheet having a means for connecting it to the outside are laminated. This is achieved by using a fixed electrode.

In the present invention, when the monomer having a sulfonic acid group is polymerized in an aqueous solution of a polyvalent metal salt,
The electrostatic interaction between the sulfonic acid anion and the polyvalent metal cation in the polyvalent metal salt aqueous solution forms bonds between the polymer molecular chains, thereby imparting electrical conductivity to the resulting gel-like composition. It imparts properties such as cohesiveness and cohesiveness. As such a monomer having a sulfonic acid group, various monomers having at least one polymerizable functional group, preferably an olefinic functional group and at least one sulfonic acid group in the molecule are used. be able to. Examples of such monomers include sulfoalkyl (meth)acrylates such as 3-sulfopropyl (meth)acrylate and 2-sulfoethyl (meth)acrylate, or 2-(
Meth)acrylamido-2-methylpropanesulfonic acid, 2-hydroxy-3-(N-sulfoethylamino)propyl-(meth)acrylate, styrenesulfonic acid, etc. can be used. Among these, sulfoalkyl (meth)acrylates can be preferably used. In particular, 3-sulfopropyl methacrylate and 2-sulfoethyl methacrylate can be preferably used.

Further, as these monomers, those whose sulfonic acid group is a salt with an organic cation or an inorganic cation can also be used. Such organic cations include ammonium ions, primary, secondary, tertiary or quaternary ammonium ions such as mono-, di-, tri- or tetraethylammonium ions, piperidinium ions, and the like. As the inorganic cation, various metal ions can be used, regardless of whether they are monovalent or polyvalent. Examples of such metal ions include ions of alkali metals such as sodium and potassium, and alkaline earth metals such as calcium. Among them, calcium ions, potassium ions, and sodium ions are preferably used.

[0009] As the other monomer to be copolymerized with the monomer having a sulfonic acid group, those which can be copolymerized with the monomer having a sulfonic acid group can be used, but the resulting gel In order to improve the water retention capacity of the gel-like composition, and in view of the fact that the other monomer is generally dissolved in a water-soluble polyhydric alcohol when producing the gel-like composition of the present invention, hydrophilic Preferably. In addition, in order to make the processability of the gel composition after polymerization easier, a hydrophilic polyfunctional monomer such as triethylene glycol-bis(meth)acrylate, which serves as a crosslinking agent, is used. Hydrophilic monofunctional monomers are also more preferred. Such other monomers include, in particular, 2-hydroxyethyl (
meth)acrylate, 2-hydroxypropyl(meth)
Hydroxyalkyl (meth)acrylates such as acrylates can be preferably used. Such monomers are not limited to one type, and multiple types of monomers can be used simultaneously.

[0010] When copolymerizing the above-mentioned other monomers with the monomer having a sulfonic acid group, the copolymerization ratio is such that the monomer having a sulfonic acid group is preferably used relative to the total monomers. is at least 10% by weight, more preferably 65-85%
The range is by weight%.

[0011] The polyvalent metal salt is used to cross-link multiple sulfonic acid anions of the polymer by electrostatic interaction via the metal cation of the salt in the hydrogel composition. It is. Therefore, the metal of the polyvalent metal salt needs to be at least divalent ions, ie, multivalent ions, when dissociated into ions. When only monovalent metal ions are used as metal cations, a water-containing gel composition cannot be produced.

[0012] As the metal of the polyvalent metal ion salt, for example, metals of group IIa, group IIb, group IIIb, etc. can be used. Among these, calcium compounds, magnesium compounds, zinc compounds, and aluminum compounds are preferably used as the polyvalent metal salt compound from the viewpoint of not causing coloration and safety, with calcium compounds being particularly preferred.

[0013] As for the type of anion forming the polyvalent metal salt, various anion species can be used as long as the polyvalent metal salt can be dissolved in water. Those having a solubility in water of 1% by weight or more are preferable, and chloride ions, nitrate ions, sulfate ions, etc. can be preferably used if pH stability and the like are also considered. In particular, chloride ions and sulfate ions can be preferably used.

[0014] Therefore, the above-mentioned polyvalent metal salts consisting of polyvalent metal cations and anions preferably have a solubility in water of 1% by weight or more, such as calcium chloride, magnesium sulfate, zinc chloride, Alum etc. can preferably be used. In particular, calcium chloride can be preferably used. Further, these salts may have crystal water or may be anhydrous.

[0015] The amount of polyvalent metal salt to be used relative to water is within a range that does not cause precipitation of the salt from the composition, regardless of before or after the polymerization reaction, so as to maintain the desired gel strength and flexibility of the resulting gel composition. Although the number can be selected as appropriate to achieve the desired value, a larger number is generally desirable in order to increase the number of electrostatic bonds between the polyvalent metal ion and the sulfonic acid group of the polymer. That is, the greater the number of electrostatic bonds between the sulfonic acid group and the polyvalent metal ion, the greater the gel strength of the resulting gel composition. Therefore, the preferred concentration of the polyvalent metal salt is 0.2 to 4.0% by weight, more preferably 1% by weight, based on the total amount of the gel composition, although it varies depending on the type of the polyvalent metal salt.
．． It ranges from 0 to 2.5% by weight.

[0016] In the present invention, general tap water can be used as water for the gel composition, but distilled water and deionized water are particularly preferably used.

A water-soluble polyhydric alcohol can be added to the gel composition of the present invention for the purpose of preventing water evaporation from the hydrogel and lowering the freezing point of the aqueous solution held in the composition. As a water-soluble polyhydric alcohol,
Those having at least 2 or more hydroxyl groups and 6 or less carbon atoms in one molecule can be preferably used. Examples include ethylene glycol, propylene glycol, diethylene glycol, and glycerin. Among them, glycerin is most preferred. The concentration of water-soluble polyhydric alcohol is
Preferably 30 to 70% by weight based on the total amount of the gel composition,
More preferably, it is in the range of 45 to 55% by weight.

In producing the gel composition in the present invention, it is preferable to sufficiently dissolve the polyvalent metal salt in the raw material mixture, and for this purpose it is preferable to use the polyvalent metal salt as an aqueous solution in advance. Such a polyvalent metal salt aqueous solution is
It can be used in an amount of 10 to 80% by weight, preferably 40 to 80% by weight, based on the gel composition. Therefore, the method for producing a gel composition of the present invention involves combining a monomer having a sulfonic acid group and other monomers as necessary with a polyvalent metal containing a water-soluble polyhydric alcohol as necessary. It is characterized by polymerization in an aqueous salt solution.

As a method for polymerizing the monomer, it is preferable to apply a general radical polymerization method known to those skilled in the art, in which the polymerization reaction is initiated by heat or ultraviolet irradiation. That is, in the polymerization reaction, monomers, aqueous polyvalent metal salt solutions, water-soluble polyhydric alcohols, and radical polymerization initiators are mixed in proportions depending on the desired performance (flexibility, conductivity, adhesiveness, etc.). This can be carried out by pouring it into a container of a desired shape and then heating or irradiating it with ultraviolet rays, thereby making it possible to obtain a gel-like composition of a desired shape and a transparent and uniform surface. In this case, as the thermal radical polymerization initiator, azobisisobutyronitrile, benzoyl peroxide, lauroyl peroxide, etc. can be used, and as the ultraviolet radical polymerization initiator, benzoin alkyl ether, benzophenone, 1- Hydroxycyclohexyl phenyl ketone and the like can be used.

[0020] The gel composition in the present invention comprises polymer 1
The amount of sulfonic acid groups per 00 g is 0.04 to 0.52 mol, preferably 0.26 to 0.44 mol.

In the gel composition of the present invention, since the monomer having a sulfonic acid group is polymerized in an aqueous solution of a polyvalent metal salt, the sulfonic acid group of the polymer and the polyvalent metal cation are electrostatically The polymer is selectively and cross-linked, thereby allowing the polymer to retain the polyvalent metal aqueous solution therein and gel it. Furthermore, when a water-soluble polyhydric alcohol is contained in the polyvalent metal salt aqueous solution, it is possible to evaporate water from the generated gel composition and lower the freezing point of the retained aqueous solution.

[0022]

[Operation] The electrode pad of the present invention is characterized in that the gel composition obtained as described above is reinforced with a sheet-like material such as a woven fabric, a non-woven fabric, or a knitted fabric. As a method for obtaining such a reinforcing body, a sheet-like polymerized gel may be attached to one or both sides of a sheet-like object.
By inserting a sheet-like material in advance into the bottom layer or intermediate layer of the container during polymerization and then injecting the prepared liquid, a reinforced electrode pad can be obtained in one step.

Further, the electrode of the present invention is obtained by laminating the above-mentioned pad and a conductive sheet provided with external connection means. The conductive sheet has the function of transmitting the current from the low-frequency treatment device to the gel-like composition attached to the skin, and transmitting the electrocardiogram signal detected by the gel-like composition to the recorder cord. Such conductive sheets include conductive carbon sheets, conductive metal sheets, or sheets printed, vapor-deposited, or pasted on part or all of a strength support material such as rubber, flexible plastic, or foamed plastic. etc. can be used. Among these, when using a strength support material, the size relationship between the conductive sheet and the strength support material may be larger as long as the gel-like composition is in contact with the conductive sheet over an area sufficient for energization. They may also be the same size.

[0024] The external connection means attached to the conductive sheet electrically reliably and easily connects the gel composition and the conductive sheet to the external low frequency treatment device oscillator or electrocardiogram recorder cord. This is what you need to connect. Such connection methods include fixing a snap-on electrical connector such as a snap fastener on the opposite side of the conductive sheet to the gel-like composition, or making the conductive sheet wider than the gel-like composition. There is a method of sandwiching the excess portion of the gel between clip electrodes. In the former case, where snap-on electrical connectors are also used, the conductive sheet may be smaller than the gel-like composition, and in the latter case, where grip electrodes are used, the conductive sheet also provides strength support to the gel-like composition. If there is a part of the surface that is not in contact with the material,
Similar to the former, the area may be smaller than that of the gel composition.

[0025] As described above, the method of forming a laminate of a conductive sheet having external connection means and a gel-like composition involves polymerizing the gel-like composition and reinforcing material into a sheet. A method may be employed in which the gel-like composition prepared above is applied to a conductive sheet, or a method may be employed in which the gel-like composition is polymerized on a conductive sheet during polymerization, resulting in a one-step operation. Among these methods, in the method of polymerizing on a conductive sheet, a bank-like weir is provided around the sheet using a strength support material that can be attached to the conductive sheet, and the prepared liquid is injected into the weir to form a gel. Polymerization of the composition not only improves work efficiency, but also improves the area of the gel and the adhesion of the electrode.

[0026]

[Examples] The present invention will be explained in more detail with reference to Examples below. The adhesive strength of the gel composition for electrodes in the examples was determined by applying the electrode gel to the bottom surface (#46 polished finish) of a stainless steel (SUS304) cylinder with a diameter of 1.0 cm with a force of 400 g.
It was measured by the peeling force (probe tack test) when pressing for seconds and pulling away at 2.0 cm/min. Example 1 23.86 parts by weight of potassium salt of 3-sulfopropyl methacrylate (hereinafter referred to as SPM), 1.0 parts by weight of calcium chloride.
56 parts by weight was dissolved in 13.68 parts by weight of water, and in this,
A solution of 0.038 parts by weight of 1-hydroxycyclohexylphenyl ketone (trade name Irgacure 184) dissolved in 53.42 parts by weight of glycerin was mixed to obtain a uniform monomer mixture. Next, place a piece of rayon non-woven fabric (basis weight 10g) in a silicone resin Petri dish of the same size as the bottom
/m2), place one sheet and fill it with the mixture to a depth of 2mm,
Lower part of 40W chemical lamp (Toshiba FL40BL)
At a position of 5 cm, the entire structure was replaced with nitrogen, and then ultraviolet rays were irradiated for 10 minutes for polymerization. The electrode pad that was peeled off from the bottom of the petri dish had an adhesive strength of 144 g, and when it was applied to the skin, it was held appropriately. Example 2 34.95 parts by weight of SPM, 2.28 parts by weight of calcium chloride, 20.35 parts by weight of water, 8.75 parts by weight of 2-hydroxyethyl methacrylate, 0.038 parts by weight of 1-hydroxycyclohexyl phenyl ketone, 35 parts by weight of glycerin.
95 parts by weight were mixed in the same manner as in Example 1 to obtain a monomer preparation. Next, 1mm from the bottom of the silicone resin container.
Polyester fiber mesh (fabric weight 60g/m
2) Fix it and pour the mixture into the container to a depth of 2mm.
Polymerization was carried out in the same manner as in Example 1. The electrode pad peeled from the container had an adhesive strength of 263 g. Example 3 The composition was the same as in Example 1 except that the monomers were one type of SPM 34.95 parts by weight and glycerin 44.7 parts by weight, and a container of the same size as the bottom was placed on the bottom of a silicone resin container. Place gauze and pour the preparation solution to a depth of 2 mm, Example 1
It was polymerized in the same way. When the electrode pad was peeled off from the container and applied to the skin, it fit well due to the flexibility of the gel. Example 4 The polyvalent metal salt is alum (KAl(SO4)2.
When an electrode pad was obtained using the same container and operation as in Example 2 with the same composition as in Example 3 except that it contained 0.75 parts by weight of 12H2O), it was found that it was not excessively retained on the skin and had good conductivity. showed that. Example 5 An electrode pad was obtained using the same composition and operation as in Example 4, except that the polyvalent metal salt was 3.0 parts by weight of zinc chloride. When attached to the stainless steel electrodes of a pair-type small low-frequency treatment device and applied to the skin, it showed excessive adhesive strength and good conductivity. Example 6 An electrode pad was obtained using the same composition and operation as in Example 4, except that the polyvalent metal salt was 1.5 parts by weight of magnesium sulfate, and it showed good conductivity. Example 7 When the electrode pad obtained in Example 1 was attached to a conductive carbon sheet having a silicone resin as a strength support material and applied to the skin, it was properly retained. Also, when connected to low-frequency therapy via a snap-type connector and flowing electricity, a good sensation of electricity was obtained. Example 8 The electrode pad obtained in Example 2 was cut into squares of 41 mm on a side and attached to the same conductive carbon sheet as in Example 1 to make a biological electrode, and then the impedance at AC voltage was measured. As a result, when the two electrodes of this example were bonded together, the resistance was 93Ω at 10Hz and 1kHz.
shows 12.9 Ω at 10 Hz, and 160 k Ω at 1 kHz when two electrodes are attached to the skin of an adult male's arm.
showed 2.68 kΩ. Example 9 A liquid preparation having the same composition as in Example 3 was dropped onto a silver foil laminated with a PET film, and the liquid was spread out, leaving a portion of the silver foil. Polymerization was carried out in the same manner as in Example 1, and when the obtained electrode was applied to the skin, it fit well due to the flexibility of the gel, and when connected to an electrocardiograph by sandwiching the exposed part of the silver foil with alligator clips, a good electrocardiogram was obtained. It was suitable as an electrocardiograph electrode. Example 10 A formulation with the same composition as in Example 4 was polymerized as in Example 1 on a PET film with a carbon print layer and a snap-on connector connected thereto. When the cord of the low-frequency therapy device was connected to the snap-type connector and the electrode was applied to the skin, it was found that it was properly retained on the skin and had good conductivity. Example 11 A liquid preparation with the same composition as in Example 5 was polymerized using the same equipment as in Example 2, and when applied to the skin on the same carbon sheet, it showed moderate adhesive strength and good conductivity. Ta. Example 12 An electrode pad was prepared in the same manner as in Example 11 except that the polyvalent metal salt was 1.5 parts by weight of magnesium sulfate, and when connected to a low frequency treatment device, a good feeling of electricity was obtained.

[0027]

According to the present invention, an electrode pad with excellent cohesiveness can be obtained by reinforcing a gel composition with a sheet-like material such as a knitted fabric, a non-woven fabric, or a net-like material. Further, according to the present invention, by forming a laminate in which a conductive sheet is bonded to a gel-like composition, it is possible to obtain an electrode that has excellent conductivity, is easy to connect to the outside, and is easy to handle. Furthermore, the softness and adhesive strength of gel compositions and pads,
Cohesiveness and the like can be adjusted by increasing or decreasing the polymer fraction in the gel as in Examples 1 and 2.

Claims (6)

[Claims] Claim 1: Consisting of a polymer of a monomer having a sulfonic acid group in the molecule, a polyvalent metal salt, and water, the polymer retains a polyvalent metal salt aqueous solution consisting of the polyvalent metal salt and water. An electrode pad made of a gel-like composition reinforced with a sheet-like material. 2. Claim 1, wherein the polymer is a copolymer of a monomer having a sulfonic acid group in the molecule and another monomer.
The electrode pad described. 3. The electrode pad according to claim 1, wherein the gel composition further contains a water-soluble polyhydric alcohol. 4. The electrode pad according to claim 1, wherein the polyvalent metal salt aqueous solution is contained in a proportion of 10 to 80% by weight based on the entire gel composition. 5. The electrode pad according to claim 1, wherein the monomer is sulfoalkyl methacrylate. 6. An electrode formed by laminating the electrode pad according to claim 1 and a conductive sheet provided with external connection means.