JPS6286076A - Ion-conductive, high-molecular self-adhesive - Google Patents

Abstract

PURPOSE:To provide the titled self-adhesive which is soft and is excellent in adhesion to the skin, conductivity, etc., by reacting a particular polyurethane polyol prepolymer with a polyurethane polyisocyanate prepolymer and an ion compound. CONSTITUTION:100pts.wt. polyurethane polyol prepolymer (a) having an alkylene oxide chain and represented by formula I (wherein A-D are each a hydrophilic and ion-conductive polymer of a linear or partially branched alkylene oxide, or a copolymer of dissimilar alkylene oxides) is reacted with 10-15pts.wt. polyurethane polyisocyanate prepolymer (b) having an alkylene oxide chain represented by formula II (wherein R is an alkyl, an alicyclic compd. or an aromatic compd.), 5-100pts.wt. plasticizer (c) (e.g., dimethoxyethylene glycol), and 0.1-5pts.wt. per pt.wt. of the component (c) of an ionic compd. (d) (e.g., NaCl) in the presence of a catalyst such as dibutyltin laurate.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an ion conductive adhesive for biological electrodes, particularly for high-performance ECG (electrocardiogram) and EEG (electroencephalogram) for biological research or biological treatment. ), an ion conductive adhesive suitable for use as a dry bioelectrode material for EOG (electrooculogram), etc.

(Prior art) Conventionally, ion-conductive adhesives have been prepared by mixing fine metal powder, carbon fibers, metal fibers, carbon powder, metal salts, etc. into a suitable clearing agent to provide a conductive effect, or adhesives that have a water-absorbing effect. Polymers such as polyhydroxyethyl methacrylate (HEMA
) etc. by absorbing water to form a hydrogel and imparting conductivity. In addition, when using this water-absorbing polymer for bioelectrodes, since it is synthesized from monomers, its viscosity is low and it does not corrode fabrics such as foams and cloth, or unreacted seven-layer polymers.
It is thought that this may have negative effects on living organisms. In addition, thin plates of highly conductive metals such as aluminum, gold, silver, platinum, and copper have been used as bioelectrode materials, but bioelectrode materials made of such metals have poor adhesion to the skin and are easily removed from the skin. Since the detection of electrical signals is insufficient, it is necessary to apply conductive jelly, cream, paste, etc. to the skin to improve contact between the electrode material and the skin, and to secure it with surgical tape, etc. to prevent it from falling off. there were. In this case, if jelly, etc. is applied, the performance may deteriorate due to heat and sweat from the skin during use, and even if you try to remove the jelly, etc. after use, there are problems such as not being fully removed and remaining. .

Therefore, a dry type bioelectrode material as shown in FIG. 1 was developed that does not require the application of such a conductive jelly or the like.

That is, this bioelectrode material has a conductive adhesive 3 provided on the back surface of a holder 2 that holds an AgCβ-Ag based electrode connector 1. As this conductive adhesive 3, for example, there is one in which a foam such as polyurethane is impregnated with a conductive liquid compound, and it is possible to detect electrical signals from the skin. Because of its poor adhesion and adhesion to the skin, it is still necessary to fix it to the skin with surgical tape or the like.

On the other hand, products have been developed in which natural polymeric polysaccharide gums such as karaya gum are mixed with polyhydric alcohol, fine salt particles, fine metal particles, etc. in order to provide adhesion and adhesion. Because it uses natural polymeric polysaccharides, the quality may vary depending on the loft where it is produced, and since it is an ionic conductor that uses water as a medium, it may be affected by moisture content and cause problems. Furthermore, it is difficult to absorb sweat from living bodies and cannot respond to changes in pH.
When used for a long period of time, allergies and bacteria are likely to occur.
There are also problems from a functional and hygienic standpoint.

In addition, fine particles of metals and salts mixed together form discontinuous conductive paths, which can accidentally create an uneven electric field and cause noise, etc. Moreover, these particles change color and turn brown during long-term storage. There is a problem in that it tends to cause discomfort or disgust when it comes into contact with the skin because of the inconvenience.

(Objectives of the Invention) The present invention has been made in view of the above circumstances, and aims to be flexible, have excellent adhesion to the skin, have excellent adhesive strength itself, have good conductivity, Provides an ion conductive polymer adhesive that has properties that alleviate sweating and skin movement, has a good feel and familiarity, and can be used continuously for a long period of time without discomfort or aversion to perform stable electrical detection. It's about doing.

(Means for achieving the object) In order to achieve the object, the ion conductive polymer adhesive of the present invention comprises a polyurethane polyol prepolymer having an alkylene oxide chain and a polyurethane polyisocyanate prepolymer having an alkylene oxide chain. The gist of this invention is to have a structure in which the chemical compound is formed by reacting the following, and contains an ionic compound.

The polyurethane polyol prepolymer used in the present invention has, for example, the following structural formula (■), and the polyurethane polyisocyanate prepolymer has, for example, the following structural formula (n).
It is a polyfunctional compound with a structure shown in the following, which has a relatively low molecular weight and is liquid at room temperature.
(C) and (D)]. In particular, polyurethane polyol prepolymer becomes a viscous resin liquid or solid at room temperature in a relatively polymeric region, and when it is reacted with polyurethane polyisocyanate prepolymer, it becomes a solid resin without tackiness, which is the object of the present invention. It is not meant to be neat. In order to exhibit adhesiveness, the size of each alkylene oxide chain and the total molecular weight must be controlled as shown in the Examples. The alkylene oxide chains (A), (B), (C), and (D) are hydrophilic and ionic conductive linear or partially functional alkylene oxide polymers or copolymers of different alkylene oxides, such as +CH, -0 -(i→CHt -CHz
-0 light, -+CH, -CH, -C1 (yo-CH knee 0÷
, →Cl! Iage 1 Sue (1) - OHOH Structural formula (I [) However, R can be any of an alkyl group, an alicyclic compound, or an aromatic compound. ) These prepolymers (1) and (If) have reactive functional groups (-〇H group and -NCO group) at their terminals or side chains, and these functional groups react to form urethane bonds. As a result, an adhesive penetrating polyurethane is formed.

This polyurethane alkylene oxide chain (A) (B
) (C) is in a state where the ionic compound is likely to form a complex. Therefore, when an ionic compound is mixed, a complex or solid solution is formed mainly at this alkylene oxide chain, and when a potential is applied, ionic conduction occurs and a current flows.

Examples of ionic compounds to be mixed include water, sodium chloride, potassium chloride, lithium chloride, lithium perchlorate, ammonium chloride, potassium chlorate, aluminum chloride, copper chloride, ferrous chloride, ferric chloride, and ammonium sulfate. , potassium nitrate, sodium nitrate, sodium carbonate, lithium borofluoride, sodium thiocyanate,
Inorganic salts such as lithium trifluoromethanesulfonate,
Organic salts such as sodium acetate, sodium alginate, sodium polyacrylate, sodium ligninsulfonate, and sodium toluenesulfonate are used.

These may be used alone or in combination.

However, when used as an adhesive for bioelectrodes, one that does not affect the human body is selected.

Such an ionic compound may be blended at the time of mixing the polyol prepolymer and the polyisocyanate prepolymer, or after the reaction, it may be impregnated as an aqueous or organic solution and the solvent may be removed by drying.

Further, if necessary, it is desirable to blend a plasticizer such as dimethoxypolyethylene glycol, for example dimethoxytetraethylene glycol, with the ionic compound to modify the adhesive. When such a plasticizer is added, the hydrogen bonds in the alkylene oxide chain are destroyed, reducing crystallinity and increasing the space for absorbing ionic compounds.
Opportunities for complex formation with ionic compounds increase, further improving conductivity.

The blending amount of the polyurethane polyisocyanate prepolymer is variable depending on the molecular weight and segment structure of the polyurethane polyol prepolymer, and is 100 parts (parts by weight, same hereinafter) of the polyurethane polyol prepolymer.
10 to 150 parts, preferably 20 to 80 parts.

The amount of the plasticizer to be blended is 5 to 100 parts, preferably 10 to 50 parts, based on 100 parts of the polyurethane polyol prepolymer. This is because if the amount is less than 5 parts, no plasticizer effect will be observed, and if it exceeds 100 parts, the mechanical strength of the polyurethane adhesive film will be lost.

In addition, when the ionic compound is melted and blended with a plasticizer, 5 to 80 parts, preferably 1 part to 100 parts of the plasticizer.
It is said to be 0 to 40 parts. This is because if it is less than 5 parts, a sufficient plasticizing effect cannot be obtained, and if it exceeds 80 parts, it becomes difficult to dissolve.

Note that a catalyst such as diptyltin dilaurate is used, and the amount of this catalyst is 0.1 to 5 parts, preferably 0.5 parts, based on 100 parts of polyurethane polyol prepolymer.
~1 part.

As mentioned above, the ion conductive polymer adhesive of the present invention is
By mixing and reacting a polyurethane polyol prepolymer, a polyurethane polyisocyanate prepolymer, an ionic compound, and preferably a plasticizer, or by mixing and reacting only the previous two components and then impregnating and drying the ionic compound etc. as a solution. In that case, if necessary, the above-mentioned mixture is coated on a substrate such as cloth, paper, plastic sheet, foam, etc. and reacted to form an appropriate shape such as a sheet, disk, mesh, etc. Form into. Unlike monomers, the prepolymers used in this case are safe because they do not leave any unreacted substances, and they have a moderate viscosity, so they can penetrate into the bubbles or seams of foams, cloth, etc. during the reaction, creating a base. This will avoid problems such as damage to the wood.

(Function and Effect) Such an ion-conductive polymer adhesive contains an ionic compound or a plasticizer mainly in the alkylene oxide chain portion of the interstitial polyurethane formed by the reaction of a polyurethane polyol prepolymer and a polyurethane polyisocyanate prepolymer. It has an intervening structure, and when a potential is applied to it, a current flows due to ion propagation, and as shown in the measurement results of Examples described later, it exhibits good conductivity with a volume resistivity of about 10 Ωcm.

Moreover, since this adhesive is a reaction product of a solvent-free prepolymer, there is no adverse effect such as skin irritation due to solvents, and the prepolymer has an alkylene oxide chain as its main chain. It is hydrophilic, non-toxic, and forms a gel-like material with excellent adhesiveness, flexibility, and skin compatibility due to urethane bonding. Therefore, even if it is not fixed with surgical tape or the like, it will adhere tightly to the skin due to its excellent adhesiveness and will not fall off. Furthermore, since it is transparent, it does not cause discomfort or disgust.

Next, an example is given (Example 1) The alkylene oxide chain (A
) (B) (C) is a polyurethane polyol prepolymer having the structure shown in Table 1 below, a polyurethane polyisocyanate prepolymer (molecule ffi: 1600, segment D: polypropylene glycol), and an ionic compound (lithium perchlorate). , a plasticizer (dimethoxytetraethylene glycol), and a catalyst (dibutyltin dilaurate) are mixed in the proportions shown in Table 1 below, and the mixture is reacted and cured at room temperature to form an ion conductive polymer adhesive test piece ( N
o, 1-6) were obtained. Regarding this test piece, JrS
The volume resistivity was measured by a method according to Section K-69115-13, and the tackiness was also examined.

The results are shown in Table 1 below. Incidentally, the segment (D) of this example uses the molecule Ef1000, and the polyurethane polyisocyanate prepolymer used is mixed with a low molecular weight polyfunctional isocyanate at the time of synthesis.

(Left below) Note) In Table 1, P-OH means polyurethane polyol prepolymer, P-NGO means polyurethane polyisocyanate prepolymer, E means polyethylene glycol,
P represents polypropylene glycol. The composition is the molecular weight ratio of each segment. In addition, ◯ indicates good adhesion, △ indicates average adhesion, and × indicates slightly poor adhesion.

(Example 2) The alkylene oxide chain (A
) (B) (C) is a polyurethane polyol prepolymer having the composition shown in Table 2 below, a polyurethane polyisocyanate prepolymer (same as in Example 1), and a catalyst (
(same as in Example 1) were mixed in the proportions shown in Table 2 below, and reacted and cured at room temperature to obtain three types of sheet pieces (No.
7 to 9) were obtained. Add this sheet piece to solution 1 (0,5
mol/12 LiC104 in ethanol solution),
Solution n (0.5 mol/E LiCβ04 water/ethanol solution), Solution m (0.5 mol/e LiCβ04)
0. A test piece was prepared by immersing the test piece in an aqueous solution of 1, drying it by leaving it at room temperature day and night, and then drying it under reduced pressure at 40°C for 2 hours. Regarding this test piece, JIS K-69115-13
The volume resistivity was measured after immersion and after drying by a method similar to the above, and the results are shown in Table 3 below.

l1l Note) In Table 2, P -011, P -NCO, P and E
is the same as in Table 1 above, and E/P indicates a copolymer of polyethylene glycol and polypropylene glycol. The composition ratio is the molecular weight ratio of each segment.

Sushi L Table Note) In Table 3, the added letters of fish are a, b, c,
d indicates presence or absence of plasticizer, a indicates no plasticizer, b indicates 5
part added, C added 10 parts, and d added 20 parts.

The ion conductive adhesive used in this example showed no cracking, bacterial growth, loss of transparency, or loss of adhesiveness over a long period of time. Conventional natural polysaccharide-based ion conductive adhesives for bioelectrodes (e.g. Karaya gum) are
It exhibits a specific volume resistivity of 0 to 10 Ωcm, and has drawbacks such as variations in quality, changes in performance due to the influence of moisture, easy growth of germs, and discoloration. based on the above results,
The ion conductive polymer adhesive of the present invention exhibits sufficient conductivity and good adhesive properties for use in biological electrodes, and good results were obtained when electrocardiograms were actually measured. , furthermore, there is no change over time,
It can be seen that the conventional problems have been solved.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a dry bioelectrode material. DESCRIPTION OF SYMBOLS 1... Electrode connector, 2... Holder, 3... Conductive adhesive.

Claims (2)

[Claims] (1) An ion-conductive polymer adhesive characterized by reacting a polyurethane polyol prepolymer having an alkylene oxide chain and a polyurethane polyisocyanate prepolymer having an alkylene oxide chain, and containing an ionic compound. agent. (2) The ion conductive polymer adhesive according to claim 1, further containing a plasticizer.