JP2005213455A - Conducting pressure sensitive adhesive composition, method for producing the same and biomedical electrode using the conducting pressure sensitive adhesive composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conducting pressure sensitive adhesive that causes reduced volume change by moisture absorption or sweat absorption. <P>SOLUTION: The composition comprises a copolymer of alkoxypolyethylene glycol mono(meth)acrylate polymer and diacetone-acrylamide polymer, propylene glycol, electrolyte and water. The resultant composition little swells with water and can easily be produced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a conductive pressure-sensitive adhesive composition that is attached to the body surface of a living body to derive an electrical phenomenon of the living body, a method for producing the same, and a biomedical electrode using the conductive pressure-sensitive adhesive composition. The present invention relates to a conductive pressure-sensitive adhesive composition with little volume change due to humidity, a method for producing the same, and a biological electrode.

A pressure-sensitive adhesive made of a polymer gel can have an appropriate adhesiveness to the surface of a living body. Therefore, a conductive material is applied to the pressure-sensitive adhesive so that a biological signal such as an electrocardiogram can be derived outside the body in the medical field. It has been suitably used for living body electrodes for introducing electrical signals into living bodies, such as living body electrodes, defibrillators, electric scalpels, and low-frequency treatment devices.

For example, when measuring a bioelectric potential, the biomedical electrode needs to be brought into direct contact with a part of the living body in order to efficiently extract a weak electric signal and guide it to an electrocardiograph or the like. However, simply touching the living body electrode element to the living body skin does not electrically connect the living body electrode element and the living body, and the unstable contact between the living body electrode element and the skin causes complex potentials and Impedance is generated, and there is a drawback that an electrical signal of a living body cannot be extracted and measured with high accuracy.

Therefore, in general, the above-mentioned biomedical electrode has a combination of a conductive jelly-like substance and a non-conductive adhesive or a conductive adhesive together with a bioelectrode element to electrically connect the living body and the electrode. I was planning.

However, a conductive jelly-like substance or a combination of a gel and a non-conductive adhesive can simultaneously satisfy good electrical performance and adhesiveness, but does not pass through a gel with a high degree of swelling due to water. When it is covered with a wet adhesive, cover, etc. and attached to the skin, the gel swells due to sweating in a sealed space, the gel leaks from the gap, or the surrounding adhesive is broken and peels off from the skin. May occur.

Therefore, conventionally, a gel composed of a water-soluble polyhydric alcohol such as glycerin, water and an electrolyte, a hydrophilic ionic or nonionic monomer, and a cross-linking polymer is used to form a gap between the living body and the electrode. The following techniques are disclosed which attempt to achieve electrical coupling of the above (see, for example, Patent Documents 1 to 4).
Japanese Patent Publication No. 3-51413 Japanese Patent Publication No. 8-19394 Japanese Patent No. 2625179 JP-A-11-290286

Conductive adhesives manufactured according to the above technique are used for patient ground plates, transcutaneous electrical nerve stimulation (TENS) electrodes, monitoring electrodes, diagnostic electrocardiogram (EKG / ECG) electrodes, and the like. While these adhesives provide excellent tack and electrical properties for certain applications, gels composed of ionic polymers swell significantly in water due to Donan's equilibrium. Further, when neutralization with acrylic acid or the like is not performed, the polymer becomes nonionic, so that the swellability in water is reduced. However, the pH of the pressure-sensitive adhesive itself is low, and it is not suitable for sticking to the skin for a long time.

Conventionally, a gel made of polyurethane is nonionic and has a small swelling property, but in order to give conductivity, it is immersed in water containing an electrolyte after forming a polymer or contains moisture in a high humidity atmosphere. There is a problem in productivity (see, for example, Patent Documents 5 and 6).
Japanese Patent Publication No. 2-9074 Japanese Patent Publication No. 3-76131

Further, as a conventional crosslinking method, there is a method of crosslinking a polymer solution containing a nonionic polymer such as polyethylene glycol or polyvinylpyrrolidone by ionizing radiation, but special equipment such as electron beam irradiation equipment is required ( For example, there are disadvantages such as Patent Documents 7 and 8.
Japanese Patent Publication No. 6-7858 US Pat. No. 5,276,079

Further, as a conventional gel preparation method, there is a method of forming a gel by crosslinking polymerization of vinyl lactam, but it is necessary to use a special crosslinking agent (see, for example, Patent Document 9), which is not preferable.
US Pat. No. 4,931,282

The problem to be solved by the present invention is to provide a conductive pressure-sensitive adhesive having a small volume change even by moisture absorption or sweat absorption. Specifically, even if the adhesive is applied to the human body for a long time, the adhesive does not swell due to humidity and sweating in the usage environment, and the moisture content does not fluctuate significantly compared to the initial moisture content. It is in providing the manufacturing method of an electroconductive adhesive, and the electrode for biological bodies using an electroconductive adhesive composition.

For example, in a neonatal intensive care unit, the relative humidity may reach 95%, and the exercise test involves a large amount of perspiration, and the electrodes used in such an environment swell due to moisture absorption, so there is little deformation. There is a need for an adhesive. The present invention has been studied for the purpose of providing such an adhesive.

As described above, an ionic crosslinked polymer containing a low molecular ion as a counter ion has a strong tendency to swell in water due to Donan's membrane equilibrium. Therefore, in order to suppress swelling in water, it is required to use a nonionic hydrophilic polymer.
The present inventor has examined the use of various hydrophilic monomers for this purpose. For example, dimethylacrylamide, hydroxyethyl acrylate, etc. are extremely irritating to the skin of the monomer, and acrylamide, N-isopropylacrylamide, etc. The monomer has neurotoxicity, and hydroxyethyl methacrylate, N-hydroxymethyl acrylamide, etc. tend to undergo a crosslinking reaction, which is thought to be caused by dehydration condensation during polymerization or after production, and it is difficult to adjust the adhesive force. As described above, vinylpyrrolidone has some problems such as requiring a special crosslinking agent, and it has been difficult to produce vinylpyrrolidone by a simple method.

As a result of various investigations to solve these problems, the present inventor has found that a composition comprising a combination of a copolymer of alkoxy polyethylene glycol mono (meth) acrylate and diacetone acrylamide, an electrolyte and water has a swelling ratio. The present invention has been found to provide a conductive adhesive composition having a small size.

That is, first, the following general formula (1)
(Wherein R ₁ represents hydrogen or a methyl group, R ₂ represents a methyl group or an ethyl group, and n represents an integer of 2 to 12) or a mixture thereof and diacetone acrylamide This is accomplished by providing a copolymer composition.

Secondly, the following general formula (1)
Wherein R ₁ represents hydrogen or a methyl group, R ₂ represents a methyl group or an ethyl group, and n represents an integer of 2 to 12, and a mixture of diacetone acrylamide and diacetone acrylamide. This is achieved by providing a conductive pressure-sensitive adhesive composition composed of a polymer, an electrolyte, and water.

Third, the following general formula (1)
Wherein R ₁ represents hydrogen or a methyl group, R ₂ represents a methyl group or an ethyl group, and n represents an integer of 2 to 12, and a mixture of diacetone acrylamide and diacetone acrylamide. This is achieved by providing a conductive pressure-sensitive adhesive composition comprising a polymer, an electrolyte and water, and further having propylene glycol added to this system.

Fourth, the following general formula (1)
(Wherein R ₁ represents hydrogen or a methyl group, R ₂ represents a methyl group or an ethyl group, and n represents 2 to 12) and diacetone acrylamide in a mixture of propylene glycol, an electrolyte and water. This is achieved by providing a method for producing a conductive pressure-sensitive adhesive composition by allowing a mercaptan compound to be present during polymerization.

Fifth, the present invention provides the following general formula (1)
(Wherein R ₁ represents hydrogen or a methyl group, R ₂ represents a methyl group or an ethyl group, and n represents an integer of 2 to 12) and a copolymer of diacetone acrylamide and propylene This is achieved by a biological electrode comprising a conductive adhesive composed of glycol, electrolyte and water and an electrode element material which is electrically conductive and has an electrical connection to the outside.

Sixth, the present invention is achieved by providing a biological electrode using the pressure-sensitive adhesive composition according to any one of the first to fourth aspects.

According to the pressure-sensitive adhesive composition of the present invention, since it contains a copolymer of alkoxy polyethylene glycol mono (meth) acrylate and diacetone acrylamide which are nonionic monomers, there is no sudden increase in water absorption even at high humidity. As a result, the bioelectrode was small and stable for a long time. In addition, since it can be easily produced in one step with light or heat, it can be used very effectively for biomedical electrodes in which swelling is a problem due to perspiration from the living body.

Hereinafter, the best mode of the pressure-sensitive adhesive composition of the present invention, the production method thereof, and the electrode on which the pressure-sensitive adhesive is carried out will be described.

The crosslinked polymer constituting the pressure-sensitive adhesive composition of the present invention has a general formula (1) as a monomer.
It contains an alkoxy polyethylene glycol mono (meth) acrylate represented by
Alkoxy polyethylene glycol mono (meth) acrylate is a compound synthesized by esterifying alkoxy polyethylene glycol with acrylic acid or methacrylic acid or by transesterification of alkoxy polyethylene glycol with acrylic acid ester or methacrylic acid ester. Alkoxypolyethylene glycol is an ethylene oxide oligomer that is synthesized by telomerization reaction of alcohol and ethylene oxide, one end of which is an alkoxy group and the other end is a hydroxy group, and there are various types having different chain lengths. The chain length (degree of polymerization) of the oligomer is determined by the synthesis conditions and purification conditions of the oligomer, but since the degree of polymerization usually has a distribution, it is not a single compound but a mixture of compounds of several degrees of polymerization. Therefore, the alkoxy polyethylene glycol mono (meth) acrylate derived therefrom is often a mixture of compounds having different chain lengths.

For example, NK ester AM series made by Shin-Nakamura Chemical Co., Ltd., Bremer AME series made by Nippon Yushi Co., Ltd. as acrylate, NK ester M series made by Shin-Nakamura Chemical Co., Ltd., Nippon Oil & Fat Co., Ltd. There are Bremer PME series.

The alkoxy polyethylene glycol mono (meth) acrylate used in the present invention is preferably a mixture of compounds in which the alkyl group is methyl or ethyl and the number of units of ethyleneoxy group (degree of polymerization) is 2 to 12, particularly Those having an average degree of polymerization of around 2 to 9 are preferred. Those with a low degree of polymerization have low hydrophilicity and electrolyte solubility, and those with a too high degree of polymerization have a low ratio of polymerizable functional groups, so the polymerization reactivity is poor and it is difficult to carry out a high ratio of copolymerization. Further, the coloring is large and the physical properties are not preferable.

Commercially available alkoxy polyethylene glycol mono (meth) acrylate contains polyethylene glycol di (meth) acrylate as an impurity, and the degree of cross-linking of the resulting cross-linked copolymer varies depending on the amount of this impurity, so care must be taken.

Diacetone acrylamide is a compound represented by the following formula 2 and is a solid having a melting point of 54 ° C. For example, it is industrially available from Kyowa Hakko Kogyo Co., Ltd. or Nippon Kasei Co., Ltd. Although this monomer is an acrylamide monomer, it is known that it does not show neurotoxicity unlike acrylamide.

The copolymerization ratio of alkoxy polyethylene glycol (meth) acrylate and diacetone acrylamide used as a monomer is 1: 3 to 3: 1, more preferably 2: 1 to 1: 2, and even more preferably 1: 1.5 to Performed at 1.5: 1. When the ratio of alkoxy polyethylene glycol (meth) acrylate alone or the ratio of alkoxy polyethylene glycol (meth) acrylate to diacetone acrylamide is greater than 3: 1, the composition is flexible and has good adhesion, but it has poor tack and obtains sufficient adhesive strength. It is difficult. Conversely, if the ratio of alkoxy polyethylene glycol (meth) acrylate to diacetone acrylamide is less than 1: 3 (a lot of diacetone acrylamide), a large amount of solvent is used to uniformly dissolve the solid diacetone acrylamide. It is necessary to use, and the tack is strong but the composition becomes hard, or the adhesion to the uneven adherend such as the skin or the curved adherend deteriorates. It becomes inferior.

The composition further contains an electrolyte and water. The electrolyte and water are necessary for imparting conductivity to the composition, and also play a role of imparting appropriate physical properties to the composition. As the electrolyte used in the present invention, ionizable salts such as sodium chloride, potassium chloride, lithium chloride, ammonium chloride, lithium perchlorate, and potassium bromide are used. In particular, alkali metal chlorides such as potassium chloride and sodium chloride are used. Is preferred. The content of the electrolyte is about 0.5% to 3% with respect to the entire composition, the content of water is 15% to 40%, and is appropriately selected according to physical properties such as conductivity and adhesiveness. For the purpose of use in biomedical electrodes, it is appropriate that the electrolyte concentration is about 1% or more, more preferably 2% or more, and the water content is 20% or more, more preferably 25% or more. When the electrolyte concentration is lowered or the water content is lowered, the impedance is increased, and depending on the shape of the electrode, there is a possibility that it is out of specification as an electrode.

In the composition of the present invention, since the alkoxy polyethylene glycol (meth) acrylate used as a monomer has an internal plasticizing effect, it can be used as an adhesive without using a plasticizer. Further, it can be used as appropriate. A suitable plasticizer is propylene glycol. Propylene glycol can be further improved in adhesive properties by adding an appropriate amount. Propylene glycol has good compatibility with the copolymer. Other polyhydric alcohols such as glycerin and sorbitol can be further used, but the composition should be determined appropriately in consideration of the compatibility of the whole composition. For example, glycerin can be added to improve moisture retention, but glycerin is not compatible with this copolymer, so using 50% or more of the polymer component may cause phase separation. There is not preferable.

For the purpose of improving the moisture retention of the composition, it is also possible to add a humectant such as lactic acid, pyrrolidone carboxylic acid or L-proline.

The feature of the present invention resides in the presence of a mercaptan when the composition precursor is polymerized in order to impart tackiness to the composition as described above.
As mentioned above, alkoxypolyethyleneglycol (meth) acrylate generally contains a compound having a plurality of polymerizable functional groups in the same molecule as an impurity, so it is apparent even in a homopolymer that should originally give a soluble linear polymer. This results in an insoluble polymer that appears to be based on crosslinking.
In order to synthesize a crosslinked gel, it is common to impart cohesion by copolymerizing a polyfunctional crosslinking monomer in addition to a monofunctional monomer. When a commercially available alkoxy polyethylene glycol (meth) acrylate is polymerized as in the present invention, the polyfunctional monomer contained as an impurity contains a larger amount than necessary to produce a pressure-sensitive adhesive. In many cases, a cohesive conductive pressure-sensitive adhesive composition having a relatively low adhesive force is provided without adding a polyfunctional crosslinking monomer.

However, when an appropriate amount of mercaptan compound is added to this system for polymerization, a conductive adhesive composition that is softer and more sticky than when polymerized with the same composition except for the addition of mercaptan is obtained. It has been found that the present invention has been reached.
The present inventor gave moderate adhesive strength by antagonizing excessive cross-linking due to the presence of an excessive cross-linking agent as described above by causing chain transfer reaction and shortening the chain length due to the presence of mercaptan. I guess that. If the amount of mercaptan added was too large, the chain length would be excessively short, or a thick composition having no cohesiveness even after sufficient polymerization was obtained.

As the mercaptan used in the present invention, one that is easily dissolved in an aqueous solvent is selected. Examples of mercaptans that can be suitably used include thioglycolic acid, its alkali metal salt, ammonium salt, 3-mercaptopropionic acid, its alkali metal salt, ammonium salt, thioglycolic acid, its alkali metal salt, ammonium salt, thiomalic acid, Examples thereof include alkali metal salts, ammonium salts and mercaptoethanol.
The amount of mercaptan used depends on the composition of the precursor, the purity of the raw material used, and the type of mercaptan, and therefore needs to be appropriately determined by experiment, but is approximately 0.1 weight based on the alkoxy polyethylene glycol (meth) acrylate used. % To 0.5% by weight is a standard. If added too much, the resulting composition will be sticky and non-aggregating. Usually, a suitable amount is found with an addition amount of 0.3% or less.

As described above, since the raw material used in the present invention usually contains a crosslinking agent as an impurity, it is generally unnecessary to add a crosslinking agent. It is possible to use one or a combination of two or more compounds having a functional functional group.
Specific examples of the compound having a plurality of unsaturated groups herein include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, and tetraethylene glycol di (meth) acrylate. Alkanediol di (meth) such as polyethylene glycol di (meth) acrylate such as propanediol di (meth) acrylate, butanediol di (meth) acrylate, pentanediol di (meth) acrylate, hexanediol di (meth) acrylate Acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, N, N'-methylenebis (meth) acrylamide, N, N'-ethylenebis (meth) acryl Bromide, and the like.
In particular, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate (n = 9,23), etc. Polyethylene glycol di (meth) acrylate is preferred.
In addition, when using these crosslinking agents together, it is necessary to increase the addition amount of the above-mentioned mercaptan compound.

Examples of the polymerization initiator used in the present invention include azo compounds such as azobisisobutyronitrile, 2,2′-azobis-2-amidinopropane hydrochloride, and radical polymerization initiators that are organic peroxides, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1- (4- (2-hydroxyethoxy) -phenyl) -2-hydroxy-2-methyl-1-propane, which is a radical polymerization initiator Examples include polymerization initiators such as acetophenones such as -1-one, benzoin ethers such as benzoin methyl ether, benzoin ethyl ether, and benzyldimethyl ketal.
In addition, you may use a polymerization initiator individually or in mixture of 2 or more types as needed.

The ratio of the cross-linked polymer and the liquid component constituting the conductive adhesive composition is an important factor for maintaining the adhesiveness and moisture absorption / release characteristics of the conductive adhesive composition to be generated appropriately. Although appropriately determined, it is preferably determined in a weight ratio of 85:15 to 40:60, more preferably 80:20 to 50:50. In order to lower the impedance, the water content must be 15% or more, preferably 20% or more, and the polymer content is necessarily 85% or less, preferably 80% or less. On the other hand, propylene glycol or the like is added to further soften the composition. However, if too much is added, the physical strength of the composition is lowered, so that the polymer concentration is suitably 40% or more.

In the pressure-sensitive adhesive composition of the present invention, the polymer itself is internally plasticized, so that it is possible to impart a flexible property without adding a plasticizer. In addition, it is necessary to add a humectant to retain moisture.

Production example

The conductive adhesive composition of the present invention can be produced by the following procedure.
First, (1) a predetermined amount of each of alkoxy polyethylene glycol mono (meth) acrylate, diacetone acrylamide, water and electrolyte salt is weighed and stirred to uniformly dissolve and mix to prepare a mixed solution. (2) Further, if necessary, other plasticizers such as propylene glycol and glycerin and a humectant are added. (3) Next, after mixing a polymerization initiator and a mercaptan compound and impregnating the prepared liquid into a non-woven fabric or putting it into a recess for storing a precursor solution, heating, light, electron beam Alternatively, the conductive pressure-sensitive adhesive composition is produced by polymerizing and crosslinking by irradiating ultraviolet rays or the like.
In particular, a method of polymerizing and crosslinking by irradiating with light, electron beam or ultraviolet rays is preferable. In the case of polymerization crosslinking by heating, the polymerization crosslinking can be almost completed within 20 minutes by setting the heating temperature to 40 ° C. to 90 ° C.
In this case, the reaction can be performed in a shorter time by increasing the heating efficiency using far infrared rays or the like.
On the other hand, in the case of polymerization crosslinking by irradiation with light, an electron beam, ultraviolet rays, or the like, particularly by ultraviolet irradiation, the polymerization crosslinking can be completed within 3 minutes by irradiating ultraviolet rays having an intensity of, for example, 50 milliwatts / cm 2. This is considered to be a more preferred embodiment industrially.

By the operation as described above, the precursor solution is uniformly polymerized and crosslinked, and the physical properties are uniformed as a whole. Therefore, a high quality conductive adhesive composition can be obtained. In the polymerization, the nonwoven fabric is impregnated with the raw material liquid and then polymerized to obtain a conductive adhesive composition with good form stability reinforced by the nonwoven fabric, which is convenient for use with electrode elements and the like. Sometimes an adhesive with good physical properties can be obtained.
In addition, when the precursor solution is irradiated with ultraviolet rays or the like in a state where the precursor solution is in contact with the electrode element, a living body electrode integrated with the element is obtained. The polymerization can be carried out in the air, but it is preferable to carry out the polymerization in an inert gas such as nitrogen in order to suppress polymerization inhibition by oxygen.
Thus, the pressure-sensitive adhesive composition of the present invention containing an electrolyte can be suitably used as a biomedical electrode by being bonded and integrated with an electrode element made of Ag / AgCl, silver, carbon, or the like.

Next, the Example at the time of using the electroconductive adhesive composition of this invention as a biomedical electrode is described with a figure.
FIG. 1 is a perspective view showing a state in which the present invention is inclined as viewed from the back. In FIG. 1, both surfaces of an annular foam tape member 1 are formed on a front surface 1a and a back surface 1b that can be bonded. A hole 2 is provided in the center of the foam tape member 1, and the conductive adhesive composition 3 of the present invention is interposed in the hole 2 to constitute a living body electrode.
FIG. 2 is a central cross-sectional view of FIG. 1 viewed from the side without tilting. In FIG. 2, an annular foam tape member 1 that can be bonded is formed by a peripheral surface 1 a and a back surface 1 b, and a sheet-like non-conductive support member 4 having the same diameter as the foam tape member 1 is formed on the back surface 1 b of the foam tape member 1. It is pasted on. From the perforation 5 provided in the vicinity of the center of the non-conductive support member 4, a conductive terminal 6 having a T-shaped flange 61 is located outside the sheet-like non-conductive support member 4 with the flange 61 inside. Is fixed integrally with the non-conductive support member 4 in a state in which is projected.
Since the biomedical electrode of the present invention is integrally bonded to one back surface of the annular foam tape member 1 with the terminal terminal 62 of the conductive terminal 6 protruding outward, these non-conductive support members Since the hole 2 is formed by the ring foam member 4 and the annular foam tape member 1, the living body electrode is formed by interposing the conductive adhesive composition 3 in the hole 2.
For electrical connection with the living body, a lead wire (not shown) is connected to the terminal terminal 62, and an electrical connection with an external electrocardiograph (not shown) is made via this lead wire.
FIG. 3 is a plan view of the biomedical electrode of FIGS. 1 and 2 as viewed from the surface 1a. As shown in the figure, a stud and an eyelet of the terminal terminal 6 are provided protruding from the center in the center portion. In this embodiment, the T-shaped ridge 61 is visible from the direction of the surface 1a of the electrode because the conductive adhesive composition 3 is transparent. The surface of the conductive terminal 6 is coated with Ag / AgCl so as to be electrically conductive.

Next, Example 1 to Example 13 of the present invention will be specifically described with reference to Tables 1 and 2 below.
The numbers in the table represent parts by weight.
The numbers in the table represent parts by weight.

Example 1 (see Table 1 above)
(1) In a solution obtained by dissolving 1.7 g of potassium chloride in 20 g of water, 33.2 g of diacetone acrylamide (manufactured by Kyowa Hakko Kogyo Co., Ltd.), methoxynonaethylene glycol acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name AM90G (R in formula 1) ₁ = hydrogen, R ₂ = methyl, n = 9 compound)) 33.2 g and propylene glycol 11 g were added and stirred to make a homogeneous solution. (2) To this solution, 0.06 g of thiomalic acid and 0.75 g of a 20% ethanol solution of benzyldimethyl ketal (2,2-dimethoxy-2-methylacetophenone) were added and dissolved uniformly to prepare a precursor solution. (3) The precursor solution was impregnated into a nonwoven fabric placed on a silicon-treated polyester film held horizontally and cast to a thickness of about 1 mm, and polymerized and cured by irradiating with ultraviolet light from a black light under a nitrogen atmosphere. A conductive adhesive composition was obtained.
This thing had moderate adhesive strength with respect to skin. (4) The biomedical electrode was obtained by injecting the precursor solution into the hole 2 without the conductive adhesive composition 3 of FIG. 2 and irradiating it with ultraviolet rays while keeping it in a nitrogen atmosphere to be cured.

Example 2 (see Table 1 above)
(1) In a solution obtained by dissolving 1.7 g of potassium chloride in 20 g of water, 33.2 g of diacetone acrylamide (manufactured by Kyowa Hakko Kogyo Co., Ltd.), methoxynonaethylene glycol acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name AM90G (R in formula 1) ₁ = hydrogen, R ₂ = methyl, n = 9 compound)) 33.2 g and propylene glycol 11 g were added and stirred to make a homogeneous solution. (2) To this solution, 0.75 g of a 20% ethanol solution of benzyldimethyl ketal (2,2-dimethoxy-2-methylacetophenone) was further added and dissolved uniformly to prepare a precursor solution. (3) The precursor solution was impregnated into a nonwoven fabric placed on a silicon-treated polyester film held horizontally and cast to a thickness of about 1 mm, and polymerized and cured by irradiating with ultraviolet light from a black light under a nitrogen atmosphere. A conductive adhesive composition was obtained. This thing had moderate adhesive strength with respect to skin. (4) The biomedical electrode was obtained by injecting the precursor solution into the hole 2 without the conductive adhesive composition 3 of FIG. 2 and irradiating it with ultraviolet rays while keeping it in a nitrogen atmosphere, and curing it.

Example 3 (see Table 1 above)
(1) In a solution of 1.7 g of potassium chloride dissolved in 20 g of water, 48.0 g of diacetone acrylamide (manufactured by Kyowa Hakko Kogyo Co., Ltd.), methoxynonaethylene glycol acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name AM90G (R in formula 1) ₁ = hydrogen, R ₂ = methyl, n = 9 compound)) 16.0 g and propylene glycol 11 g were added and stirred to make a homogeneous solution. (2) 0.06 g of thiomalic acid and 0.75 g of a 20% ethanol solution of benzyldimethyl ketal (2,2-dimethoxy-2-methylacetophenone) were further added to this solution and uniformly dissolved to prepare a precursor solution. (3) The precursor solution was impregnated into a nonwoven fabric placed on a silicon-treated polyester film held horizontally and cast to a thickness of about 1 mm, and polymerized and cured by irradiating with ultraviolet light from a black light under a nitrogen atmosphere. A conductive adhesive composition was obtained. This thing had moderate adhesive strength with respect to skin. (4) The biomedical electrode was obtained by injecting the precursor solution into the hole 2 without the conductive adhesive composition 3 of FIG. 2 and irradiating it with ultraviolet rays while keeping it in a nitrogen atmosphere to be cured.

Example 4 (see Table 1 above)
(1) In a solution of 1.7 g of potassium chloride dissolved in 20 g of water, 48.0 g of diacetone acrylamide (manufactured by Kyowa Hakko Kogyo Co., Ltd.), methoxynonaethylene glycol acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name AM90G (R in formula 1) ₁ = hydrogen, R ₂ = methyl, n = 9 compound)) 16.0 g and propylene glycol 11 g were added and stirred to make a homogeneous solution. (2) 0.06 g of thiomalic acid and 0.75 g of a 20% ethanol solution of benzyldimethyl ketal (2,2-dimethoxy-2-methylacetophenone) were further added to this solution and uniformly dissolved to prepare a precursor solution. (3) The precursor solution was impregnated into a nonwoven fabric placed on a silicon-treated polyester film held horizontally and cast to a thickness of about 1 mm, and polymerized and cured by irradiating with ultraviolet light from a black light under a nitrogen atmosphere. A conductive adhesive composition was obtained. This thing had moderate adhesive strength with respect to skin. (4) The biomedical electrode was obtained by injecting the precursor solution into the hole 2 without the conductive adhesive composition 3 of FIG. 2 and irradiating it with ultraviolet rays while keeping it in a nitrogen atmosphere to be cured.

Hereinafter, for Examples 5 to 13 in Table 1 and Table 2, the pressure-sensitive adhesive composition and the biomedical electrode were prepared in the same manner as in Examples 1 to 4 by changing the type and addition amount of the raw material components. This is shown as a blended composition and description is omitted.

In Examples 1 to 13, DAAM is diacetone acrylamide, AM90G is NK ester AM90G (methoxynonaethylene glycol acrylate) manufactured by Shin-Nakamura Chemical, and M90G is NK ester M90G (manufactured by Shin-Nakamura Chemical. Methoxynonaethylene glycol methacrylate), AM30G is NK ester AM30G (methoxytriethylene glycol acrylate) manufactured by Shin-Nakamura Chemical Co., Ltd., and ethanol solution of benzyldimethyl ketal is 20 of benzyldimethyl ketal (2,2-dimethoxy-2-methylacetophenone). Each represents a% ethanol solution.

Impedance Measurement The results of measuring impedance using the biological electrode of Example 1 of the present invention will be described. When two biomedical electrodes were bonded face to face, an alternating current of 10 Hz was passed between the elements and the impedance was measured, it was 250Ω. In addition, this electrode was attached to the chest and abdomen of 10 men and women, and the impedance, electrocardiogram waveform and respiratory waveform were measured. The impedance when an alternating current of 10 Hz was applied was 241 kΩ on average for 10 men and women, and in both cases, an electrocardiogram waveform and a respiratory waveform could be measured without any problem.

Comparative Example The biological electrodes of Examples 1, 3 and 5 of the present invention will be described in comparison with conventional comparative examples.
(1) A slurry prepared by mixing 31 g of 2-acrylamido-2-methylpropanesulfonic acid with 13.5 g of water was slowly added to 15 g of 47% aqueous sodium hydroxide solution with cooling and stirring, and further 31 g of propylene glycol and 3 methylenebisacrylamide. 1.2 g of 2% aqueous solution was added. (2) 17.5% hydrochloric acid was added dropwise to this solution with stirring to adjust the pH to 7.5. (3) Further, 25 g of glycerin and a 2% ethanol solution of benzoin ethyl ether were added to obtain a comparative example of the precursor solution.
A similar electrode was prepared by the same method as in Example 1, and the impedance when directly bonded to the precursor, the impedance when bonded to the human body, and the monitor waveform were measured. The impedance when directly pasted was 100 Ω at 10 Hz, and the impedance when pasted on the human body was 226 kΩ on an average of 10 people, and there was no hindrance to observation of the electrocardiogram waveform and respiratory waveform in any subject.

Swelling test
A swelling test was performed on the biomedical electrodes of Examples 1, 3 and 5 and the comparative electrode.
(1) The biomedical electrodes of Example 1, Example 3 and Example 5 and the electrode of the comparative example were immersed in water so that the surface of the conductive adhesive composition was sufficiently immersed in water and occasionally taken out, and the weight was measured. (2) The weight of the conductive adhesive composition was calculated from the difference between the weight of members other than the conductive adhesive composition measured in advance and the weight of the entire electrode. (3) Next, the degree of swelling (weight of conductive adhesive composition after water immersion / initial conductive adhesive composition weight) was calculated by comparison with the weight of the initial conductive adhesive composition. The result is shown in FIG.
The electrode of the comparative example was destroyed after 180 minutes and measurement was impossible. On the other hand, Examples 1, 3 and 5 of the present invention gradually increased up to 300 minutes, slightly swollen from 2 to 3, and swelled from 300 to 400 minutes. Was found to hardly swell from 4 to 5. Moreover, it was found that Example 5 was slightly swollen with a degree of swelling of 5.7 to 7.3.

Adhesive strength and swelling degree Using the conductive adhesive compositions of Examples 1 to 13, a biomedical electrode having the shape in which the conductive adhesive composition 3 of the present invention was disposed was prepared. Measurements were made.
The adhesive strength was measured by creating a 25 mm wide sample lined with a nonwoven fabric (WP8085 made by Nippon Vileen Co., Ltd.) on a 1 mm thick adhesive composition containing a nonwoven fabric, and a rigid polyvinyl chloride plate (T-932 made by Takiron Co., Ltd.). It was peeled off at a constant speed of 100 mm / min in the vertical direction, and the maximum value of the stress was measured.
Tables 3 and 4 show the results of measuring the maximum value of the stress in the same manner by attaching a sheet of the pressure-sensitive adhesive composition to a certain place inside the human forearm to evaluate the adhesive strength to the human body.
The degree of swelling was evaluated by the method described above.
Tables 3 and 4 below show the test results of adhesive strength and swelling degree.
As can be seen from the examples, Examples 1 to 13 have a low degree of swelling after immersing in water for 100 minutes, ranging from 2.7 to 3.1, whereas the comparative example has 7.7. . Moreover, although the swelling degree after 180-minute water immersion of Example 1 to Example 13 is increasing slightly in the range of 3.5 to 4.0, it is significantly less than 23 of the comparative example. Moreover, although the swelling degree after 300-minute water immersion of Example 1 to Example 13 is increasing with the range of 4.3 to 5.7, compared with the thing of the thing of a comparative example, it can still use. In addition, the swelling degree after immersion for 420 minutes in Examples 1 to 13 increased from 4.7 to 7.3, but it was still in use so as not to be compared with the damaged one in the comparative example. It turns out that it can serve.

As described above, the pressure-sensitive adhesive composition of the present invention contains a copolymer of alkoxypolyethylene glycol mono (meth) acrylate and diacetone acrylamide, which are nonionic monomers, and the constituent monomers complement each other in flexibility and tack. Therefore, the water absorption rate does not increase rapidly even at high humidity, and the composition is excellent in adhesive performance. Further, it has an excellent effect that it can be easily produced in one step by light or heat, and can be used for a living body electrode in which swelling due to perspiration or the like becomes a problem.

It is the perspective view which looked in the state which inclined this invention from the back surface in the state which made the hole 2 inside the center of the cyclic | annular foam tape member 1 have the electroconductive adhesive composition 3 interposed. It is the center sectional view seen from the side in the state where FIG. 1 is not inclined. It is the top view which looked at the biomedical electrode of FIG. 1, FIG. 2 of this invention from the direction of the surface 1a. The figure which showed the relationship between the immersion time and swelling degree of an electroconductive adhesive composition.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Foam tape member 1a Front surface 1b Back surface 2 Hole 3 Conductive adhesive composition 4 Nonelectroconductive support member 5 Perforation 6 Conductive terminal 61 T type cage

Claims (7)

The following general formula (1)
(Wherein R ₁ represents hydrogen or a methyl group, R ₂ represents a methyl group or an ethyl group, and n represents an integer of 2 to 12) or a mixture thereof and diacetone acrylamide Copolymer composition. The following general formula (1)
(Wherein R ₁ represents hydrogen or a methyl group, R ₂ represents a methyl group or an ethyl group, and n represents an integer of 2 to 12) or a mixture thereof and diacetone acrylamide A conductive pressure-sensitive adhesive composition comprising a copolymer, an electrolyte, and water. The conductive adhesive composition according to claim 2, comprising propylene glycol. The conductive pressure-sensitive adhesive composition according to any one of claims 2 to 3, wherein the weight ratio of the compound represented by formula (1) to diacetone acrylamide is 1: 3 to 3: 1. The following general formula (1)
(Wherein R ₁ represents hydrogen or a methyl group, R ₂ represents a methyl group or an ethyl group, and n represents an integer of 2 to 12), a solvent containing an electrolyte and water, diacetone acrylamide A method for producing a conductive pressure-sensitive adhesive composition, wherein a mercaptan compound is present for copolymerization therein. The mercaptan compound to be present in the method for producing a conductive adhesive composition is thioglycolic acid, its alkali metal salt, ammonium salt, 3-mercaptopropionic acid, its alkali metal salt, ammonium salt, thioglycolic acid, its alkali metal salt, The method for producing a conductive pressure-sensitive adhesive according to claim 5, wherein the method is one selected from ammonium salt, thiomalic acid, alkali metal salt thereof, ammonium salt, and mercaptoethanol, or a mixture thereof. The following general formula (1)
(Wherein R ₁ represents hydrogen or a methyl group, R ₂ represents a methyl group or an ethyl group, and n represents an integer of 2 to 12) and a copolymer of diacetone acrylamide and propylene A biological electrode comprising a conductive pressure-sensitive adhesive composed of glycol, an electrolyte and water and an electrode element material which is electronically conductive and has an electrical connection to the outside.