JPS63131406A - Conducting composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a conductive composition that can be applied to various electrodes in addition to electrocardiogram electrodes.

[Conventional technology]

Generally, electrodes such as electrocardiogram electrodes are used by being attached to the human skin using a conductive composition that has rubber elasticity and adhesive properties.

As such a conductive composition, a polymer electrolyte, a water-soluble polymer, or a wood-philic polymer containing an electrolyte is generally used as the conductive polymer, and is used in a hydrogel state. In such conventional conductive compositions, the main component of the hydrogel is the above-mentioned conductive polymer, and as mentioned above, the above-mentioned conductive polymer is a polymer electrolyte, a water-soluble polymer, or a hydrophilic polymer. be. Therefore, conventional conductive compositions tend to lack affinity and adhesiveness to oily surfaces such as human skin. Furthermore, a disadvantage of the water-soluble polymers and the like is that their original shape easily changes due to swelling or dissolution in water, which tends to cause problems during storage, transportation, etc.

[Problem that the invention seeks to solve]

In order to solve the problem of affinity for oily surfaces such as the human body, adhesion, and deformation due to moisture, carbon particles, which are conductive substances, are dispersed in the rubber component, thereby forming a conductive composition. A method was proposed. However, since this material does not contain water, the electrical contact resistance with respect to the skin is high and the conductivity does not reach the desired range. It is also possible to disperse or emulsify the electrolyte with water in a continuous phase such as rubber, but this method also does not provide sufficient conductivity and at the same time causes the water to bleed outside the system. It also has the disadvantage of being easy to use, so it is not practical.

This invention was made in view of the above circumstances, and provides a conductive composition that has a high affinity for oily surfaces such as those of the human body, does not easily change its original shape due to moisture, etc., and has high conductivity. Its purpose is to provide.

[Means for solving problems]

In order to achieve the above object, the conductive composition of the present invention has bentonite particles that have absorbed water and are in an integrated state distributed in a continuous phase mainly composed of a rubber component and an oil component. The structure is such that conductivity is imparted through mutual electrical contact between the bentonite particles that have absorbed water.

That is, unlike conventional electrolyte polymers or water-soluble polymers containing electrolytes, this conductive composition has a continuous phase mainly composed of a rubber component and an oil component, and the continuous phase contains only water. Bentonite does not exist as a dispersed or emulsified state, but is absorbed into bentonite and exists in an integrated state. Therefore, it does not cause bleeding, etc., and has a high affinity for human skin.Moreover, due to the action of the water-containing bentonite particles, the electrical contact resistance to the skin is low.

As a result, combined with electrical contact between bentonite particles, a high degree of electrical conductivity is exhibited. Furthermore, since the conductive composition of the present invention has a rubber component and an oil component as its main components, and does not contain a water-soluble polymer or the like as a main component, it does not cause swelling due to humidity or water. First, the initial shape can be maintained for a long period of time.

To explain in more detail, in the conventional oil-soluble polymer-based hydrogel, water particles are emulsified in the form of a W10 emulsion, whereas in the conductive composition of the present invention, water is absorbed by bentonite and integrated. Furthermore, these particles do not exist in the conventional form of emulsified particles in the rubber or oily continuous phase (usually as relatively large granular agglomerates in which fine particles are connected), and the water-absorbing bentonite agglomerates It is presumed that a part of the body is exposed on the surface of the conductive composition, and the rest is connected inside the conductive composition and distributed in electrical contact. It is thought that the excellent effects described above can be obtained.

In addition, in this invention, water-absorbing bentonite particles are
It is intended to include not only the original particles but also agglomerates formed by connecting fine particles such as those described above.

Such a conductive composition uses a rubber component and an oil component,
It can be obtained by using a tackifying component or the like as required.

Examples of the rubber component include ABA type teleblock copolymer elastomer. In this case, the A block is preferably made of a hard polymer of a vinyl compound such as styrene or methylstyrene, and the B block is preferably made of a soft polymer of a conjugated diene compound such as butadiene or isoprene. In addition, natural rubber, isoprene rubber, etc. can also be used. These may be used alone or in combination without any problem.

Examples of the oil component used together with the rubber component include machine oil, cylinder oil, transformer oil, rosin oil, various liquid paraffins, and vegetable oils such as salad oil.

These may be used alone or in combination. The amount of this oil component to be used is preferably set to about 100 parts per 5 to 120 parts by weight (hereinafter abbreviated as "parts") of the rubber component.

Examples of the tackifying component include rosin, modified rosin, petroleum resin, polyterpene resin, polybutene, liquid polyisobutylene, and the like.

These may be used alone or in combination. When used, the amount used is 10% of the above rubber component.
Good results can be obtained by setting the amount within the range of 50 to 300 parts relative to 0 parts.

In addition to the above components, an emulsifier is usually used. As this emulsifier, nonionic surfactants and anionic surfactants are mainly used. Examples of the nonionic surfactants include polyethylene glycol oleyl ether, polyethylene glycol nonylphenyl ether, and sorbitan monolaurate. Examples of the anionic surfactants include polyethylene glycol alkyl ether phosphate, magnesium stearate, aluminum stearate, calcium stearate, and zinc stearate.

The amount of these emulsifiers used is 1 to 20 parts per 100 parts of water.
It is preferable to set the value within the range of .

In the conductive composition of the present invention, bentonite is used in a water-absorbed state together with the above-mentioned components, and this is a major feature. The above bentonite is usually used in combination with water, and water accounts for 5 to 50% of the total conductive composition.
It is preferable to set the bentonite in a range of 70% by weight (hereinafter abbreviated as "%"), and set the bentonite at a ratio of 5 to 100 parts per 100 parts of water.

The conductive composition of the present invention can be produced using the above-mentioned raw materials, for example, in the following manner. That is, the rubber component, oil component, and tackifier component are mixed in a predetermined ratio, and the mixture is heated to about 80 to 150° C. to dissolve. Next, an emulsifier and the like are added to this melt and mixed. On the other hand, water and bentonite are mixed at a temperature of 40 to 100°C to form an integrated state (water is absorbed by bentonite and coexist in the same phase), and this is added to the above mixture. Mix well. In this way, the desired electrically conductive composition is obtained. This conductive composition is usually used by being coated on a support such as a nonwoven fabric or a synthetic resin film.

In the conductive composition thus obtained, bentonite absorbs water and is in an integrated state, so that water stably exists even in a high water content state.

Therefore, the adhesive force decrease phenomenon due to surface bleeding of water does not occur.

Note that although a tackifying component is used in the above example, when the conductive composition is used for applications that do not require tackiness, the use of the tackifying component can be omitted.

〔Effect of the invention〕

As described above, the conductive composition of the present invention includes a rubber component,
Bentonite particles, which absorb water and become integrated, are distributed in electrical contact in the continuous phase whose main component is oil, so water remains stable even in a highly hydrous gel state. It has high conductivity, good affinity for the skin, and does not deform due to moisture absorption. That is, the electrically conductive composition of the present invention exhibits excellent characteristics not seen in previous products due to its unique structure not seen in previous products.

Next, examples will be described together with comparative examples.

[Example 1] 100 parts of liquid paraffin with a viscosity of 170 cp (20°C),
Polyterpene resin (manufactured by Yasuyu Kogyo Co., Ltd., YS Resin PX
#800) and 50 parts of styrene-butadiene-styrene teleprotox elastomer (Califlex TRll0I, manufactured by Shell Chemical Co., Ltd.) were heated and dissolved at 110°C. Next, 10 parts of an emulsifier (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Neugen EA80) and 5 parts of magnesium stearate were added to the above-mentioned dissolved material. Then, while maintaining the temperature at 80 to 90°C, a mixture of 60 parts of bentonite (pharmaceutical product) dispersed in 200 parts of water is added and dispersed into the mixture to form the desired hydrogel-like conductive composition. I got something.

Next, the conductive composition obtained as described above was spread on a polyester nonwoven fabric to a thickness of 1 fl, and a sample was prepared.

[Example 2] Liquid paraffin (Sumoil P-55, manufactured by Matsumura Oil Research Institute)
) 120 parts, styrene-isoprene-styrene teleblock elastomer (manufactured by Shell Chemical Co., Ltd., Kaliflex T
90 parts of R1107) and 150 parts of petroleum resin (Alcon P-70, manufactured by Arayo Kagaku Co., Ltd.) were heated and dissolved at 120°C, and 20 parts of an emulsifier (Solgen S-40, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) was dissolved therein.
1 part, and 5 parts of magnesium stearate were added and mixed.

Next, while maintaining this at 80 to 90°C, a mixture of 60 parts of bentonite (pharmaceutical product) dispersed in 300 parts of water was added and dispersed therein to obtain the desired conductive composition. .

The conductive composition obtained as described above was spread on a nonwoven fabric in the same manner as in Example 1 to prepare a sample.

[Comparative Example 1] The same amount of precipitated calcium carbonate (pharmacopoeia product) was used in place of bentonite. A sample was prepared in the same manner as in Example 1 except for the above.

[Comparative Example 2] Precipitated calcium carbonate (pharmacopoeia product) was used in place of bentonite. A sample was produced in the same manner as in Example 2 except for this.

The adhesive force and change over time of the sample obtained as described above were measured. The results are shown in Table 1 below.

(Margin below) (Adhesion test method) Prepare a test piece with a width of 20 m and a length of 250 m. Wash the phenol resin board with acetone in advance, dry it thoroughly, and wipe it with a dry clean cloth. Paste the test piece and
A rubber roller was passed over it twice at a speed of 300 cranes/min, and after 30 minutes, a load of 9 was applied when peeling with 180@beer at a speed of 300 n/min using a Schottspa pendulum type tensile tester. It was measured.

From Table 1, although the initial adhesive strength of the tested product is slightly inferior to that of the comparative product, the adhesive strength actually increases over time, which is in sharp contrast to the comparative example, which significantly decreases over time. is doing. Moreover, it can be seen that the comparison product has a significantly high electrical resistance and has a major drawback in conductivity, whereas the practical product has a significantly low resistance value and is extremely rich in conductivity.

[Brief explanation of the drawing]

The drawing is a time/weight reduction rate curve diagram of the implemented product and the comparative product.

Claims (2)

[Claims] (1) In the continuous phase whose main components are a rubber component and an oil component,
Conductivity characterized in that bentonite particles that have absorbed water and are in an integrated state are distributed, and conductivity is imparted by mutual electrical contact of the bentonite particles that have absorbed water. Composition. (2) The conductive composition according to claim 1, wherein the continuous phase contains a tackifying component.