Patent Description:
Techniques for electronically measuring human biometric information using textile-type wearable devices are gaining attention. Here, the textile-type wearable devices refer to devices that can take measurements or be operated while being worn as a garment. As a material of the textile-type wearable devices, fibers coated with highly conductive resin have been developed.

Document <CIT> discloses a sheet-like stretchable electrode sheet and a stretchable wiring sheet for wearable biological information measurement, that are capable of being laminated on a substrate. This document is focused merely on stopping a production of cracks by using an elongation stopper to suppress the elongation of a fabric but fails to disclose at least a stretchable protection layer as disclosed in amended claim <NUM>.

Document <CIT> relates to a fabric for marking and a method of forming a mark with the same, and particularly to a fabric for marking caused to adhere to various kinds of clothes such as casual wears, uniforms and swimming suits to form a mark on the surface of such an adherent as those clothes.

Document <CIT> relates to an adhesive tape which is permanently pressure-sensitively adhesive over the entire surface, being preferably unbacked, and being composed of a film of a pressure sensitive adhesive which is coated onto an antiadhesive medium.

Stretchable conductive films are also disclosed in<NPL> and <NPL>.

An object of the present invention is to provide a stretchable conductive film for textiles as described below. The conductive film can be easily attached to textile fabric, and has electrical conductivity and stretch properties.

A stretchable conductive film for textiles according to the present invention includes a stretchable conductive layer having stretch properties, and a hot-melt adhesive agent layer formed on one surface of the stretchable conductive layer. The stretchable conductive layer is configured from a conductive composition including an elastomer and a conductive filler filling the elastomer.

In this configuration, the stretchable conductive film for textiles (hereinafter referred to as "stretchable conductive film") may be attached to a textile fabric as follows, for example. First, the stretchable conductive film is cut to a shape in accordance with the purpose of use. Then, the stretchable conductive film is placed on the textile fabric in such a way that the surface of the stretchable conductive film on the side of the hot-melt adhesive agent layer opposes the textile fabric. Then, an iron or the like is used to thermally bond the stretchable conductive film to the textile fabric. In this way, the stretchable conductive film including the stretchable conductive layer and the hot-melt adhesive agent layer is placed in a state of being attached to the textile fabric.

That is, in this configuration, the stretchable conductive film for textiles can be obtained which can be easily attached to the textile fabric. The stretchable conductive layer includes the conductive composition having an elastomer and a conductive filler filling the elastomer. Therefore, the stretchable conductive film for textiles as attached to the textile fabric is electrically conductive and has stretch properties.

The present invention further includes a peel film formed on a surface of the hot-melt adhesive agent layer on the opposite side from the stretchable conductive layer side.

An embodiment not according to the invention includes a first peel film formed on a surface of the stretchable conductive layer on the opposite side from the hot-melt adhesive agent layer side; and a second peel film formed on a surface of the hot-melt adhesive agent layer on the opposite side from the stretchable conductive layer side.

The present invention further includes a stretchable protection layer having stretch properties and formed on at least a part of a surface of the stretchable conductive layer on the opposite side from the hot-melt adhesive agent layer side, wherein the stretchable protection layer includes an elastomer that is filled with carbon black.

An embodiment of the present invention further includes a stretchable protection layer having stretch properties and formed on at least a part of the surface of the stretchable conductive layer on the opposite side from the hot-melt adhesive agent layer side, and a peel film formed on a surface of the hot-melt adhesive agent layer on the opposite side from the stretchable conductive layer side.

An embodiment of the present invention further includes a stretchable protection layer having stretch properties and formed on at least a part of the surface of the stretchable conductive layer on the opposite side from the hot-melt adhesive agent layer side; a first peel film formed on the surface of the stretchable conductive layer on the opposite side from the hot-melt adhesive agent layer side so as to cover the stretchable protection layer; and a second peel film formed on the surface of the hot-melt adhesive agent layer on the opposite side from the stretchable conductive layer side.

In an embodiment of the present invention, the conductive filler is dendritic.

In an embodiment of the present invention, the conductive filler is a dendritic silver powder.

In an embodiment of the present invention, the conductive filler is a silver-coated copper powder including a dendritic copper powder coated with silver.

In an embodiment of the present invention, the conductive filler has a coil shape.

The above and other purposes, features, and effects of the present invention will become apparent from the following description of embodiments with reference made to the attached drawings.

<FIG> is a schematic cross sectional view illustrating a configuration of a stretchable conductive film for textiles (not according to the invention).

The stretchable conductive film for textiles (hereafter simply referred to as "stretchable conductive film <NUM>") includes a first peel film (transfer film) <NUM>, a stretchable conductive layer <NUM>, a hot-melt adhesive agent layer <NUM>, and a second peel film (protection film) <NUM>. The stretchable conductive layer <NUM> is formed on one surface of the first peel film <NUM>. The hot-melt adhesive agent layer <NUM> is formed on a surface of the stretchable conductive layer <NUM> on the opposite side from the first peel film <NUM> side. The second peel film <NUM> is formed on a surface of the hot-melt adhesive agent layer <NUM> on the opposite side from the stretchable conductive layer <NUM> side. The stretchable conductive film <NUM> is sheet-shaped. The stretchable conductive film <NUM> may have an elongate shape longer in one direction.

As the first peel film <NUM>, examples that may be used include peel paper (release paper); fluorine films; polyethylene naphthalate (PEN) films having a silicone-based or non-silicone-based (such as melamine-based or acrylic-based) mold-release agent applied to one or both surfaces thereof; and polyethylene terephthalate (PET) films. As the second peel film <NUM>, examples similar to those of the first peel film <NUM> may be used.

Examples of the material of the hot-melt adhesive agent used for the hot-melt adhesive agent layer <NUM> include thermoplastic resins, such as polyesters, polyurethanes, polyamides, olefins, and ethylene-vinyl acetates. In the present invention, the hot-melt adhesive agent preferably has a melting point of not more than <NUM>, durometer hardness of not more than 95A, and rupture elongation of not less than <NUM>%, and more preferably a melting point of not more than <NUM>, durometer hardness of not more than 85A, and rupture elongation of not less than <NUM>%. More specifically, as the hot-melt adhesive agent, a polyurethane-based thermoplastic resin may be used, such as "SHM101-PUR" (product name) manufactured by Sheedom Co.

The stretchable conductive layer <NUM> is configured from a conductive composition including an elastomer and a conductive filler filling the elastomer.

The elastomer is an elastic resin, such as a styrene-based elastomer, an olefin-based elastomer, a polyester-based elastomer, a polyurethane-based elastomer, a polyamide-based elastomer, and a silicone-based elastomer. A polyurethane-based elastomer is configured from a hard segment and a soft segment. Examples of the soft segment include carbonates, esters, and ethers. The soft segment, in terms of physical properties, preferably has <NUM>% modulus of <NUM> to <NUM> MPa, rupture strength of <NUM> to <NUM> MPa, rupture elongation of <NUM> to <NUM>%, permanent strain of not more than <NUM>%, and a thermal softening point of not less than <NUM>, and more preferably <NUM>% modulus of <NUM> to <NUM> MPa, rupture strength of <NUM> to <NUM> MPa, rupture elongation of <NUM> to <NUM>%, permanent strain of not more than <NUM>%, and a thermal softening point of not less than <NUM>.

Specific examples that may be used include NE-<NUM>, MAU-<NUM>, NE-<NUM>, NE-302HV, and CU-<NUM> manufactured by Dainichiseika Color & Chemicals Mfg. As a polyurethane-based elastomer, PANDEX 372E manufactured by DIC corporation may be used. The elastomer may comprise a single resin, or may include a plurality of kinds of resin. The elastomer, from the viewpoint of improving manufacturability (processability), flexibility and the like, may include an additive such as a plasticizer, a processing aid, a cross-linker, a vulcanization accelerator, a vulcanization aid, an anti-oxidant, a softener, and a coloring agent.

The shape of the conductive filler may be dendritic, coiled, clumpy, spherical, flaky, needle-like, fibrous, or the like. A dendritic shape refers to a shape in which bar-shaped separating branches extend in <NUM>-dimensional directions or <NUM>-dimensional directions from a bar-shaped main branch. A dendritic shape include a shape in which the separating branches are bent in the middle, and a shape in which additional bar-shaped separating branches extend from the middle of the separating branches.

A dendritic conductive filler will be described. The dendritic conductive filler may be a dendritic copper powder or silver powder, for example. The dendritic conductive filler may be a silver-coated copper powder comprising a dendritic copper powder with a silver coating, or a gold-coated copper powder comprising a dendritic copper powder with a gold coating. When the conductive filler is made from a dendritic silver-coated copper powder, a conductive filler which can be obtained is relatively inexpensive, has a resistance value close to that of a conductive filler made from silver, and has excellent electrical conductivity and migration resistance. When the conductive filler is made from a dendritic copper powder, a conductive filler can be obtained which is inexpensive and yet has a low resistance value.

When the conductive filler is made from a dendritic silver-coated copper powder, a polyurethane-based elastomer is preferably adopted as the elastomer. In this case, polyurethane-based elastomers have a volume resistivity of 10E+ <NUM> to <NUM>Ωcm, which is lower than that of other elastomers by approximately two orders of magnitude, and have high affinity with respect to a silver-containing conductive filler. Accordingly, the polyurethane-based elastomer enables the conductive composition to stretch well.

The conductive filler has a grain size lower limit of <NUM>, or preferably <NUM>. When the lower limit is not less than <NUM>, the conductive filler grains are more likely to contact each other, and the conductivity of the conductive composition is improved. The conductive filler has a grain size upper limit of <NUM>, or preferably <NUM>. When the upper limit is not more than <NUM>, it becomes possible to decrease the thickness of the conductive layer made from the conductive composition.

When the conductive filler has a coil shape (including a helix shape and a spiral shape), the conductive filler, upon stretching of the elastomer, extends as if a coil were pulled. Thus, even when the elastomer is stretched, an increase in the resistance value of the conductive composition can be suppressed. In this way, it becomes possible to provide a conductive composition that has stretch properties and that can suppress an increase in resistance value when stretched.

Examples of the stretchable conductive layer <NUM> will be described.

Table <NUM> indicates Examples <NUM> to <NUM> of the stretchable conductive layer <NUM>.

In a polyurethane-based elastomer (PANDEX 372E manufactured by DIC corporation), a dendritic silver-coated copper powder with an average grain size of <NUM> (manufactured by MITSUI MINING & SMELTING CO. ) was blended such that the filling factor of the silver-coated copper powder (filling factor of the conductive filler in the conductive composition) became <NUM> mass %. Then, to <NUM> parts by mass of the polyurethane-based elastomer, <NUM> parts by mass of a mixed solvent of isopropyl alcohol and toluene (isopropyl alcohol to toluene weight ratio <NUM>:<NUM>) was added and stirred using a planetary mixer. In this way, a solution containing the polyurethane-based elastomer, the silver-coated copper powder, and organic solvent (hereinafter referred to as "conductive solution") was obtained.

Then, the conductive solution was applied to one surface of a peel film using an applicator so that the film thickness after drying became <NUM>, and heated to dry. The heating and drying step involved heating and drying with hot air at <NUM>, heating and drying with hot air at <NUM>, and heating and drying with hot air at <NUM>, each for two minutes. In this way, a thin film of conductive composition (hereinafter referred to as "conductive layer") was formed on one surface of the peel film.

The conductive layer was cut to a predetermined size, and then the peel film was peeled from the conductive layer. In this way, samples b1, b2, and b3 of the stretchable conductive layer <NUM> were obtained.

A conductive layer was formed on one surface of a peel film in the same way as in Example <NUM>, with the exception that in the polyurethane-based elastomer, a dendritic silver-coated copper powder was blended so that the filling factor of the silver-coated copper powder became <NUM> mass %, and that the mixed solvent was <NUM> parts by mass with respect to <NUM> parts by mass of the polyurethane-based elastomer. After the conductive layer was cut to a predetermined size, the peel film was peeled from the conductive layer. In this way, samples c1, c2, and c3 of the stretchable conductive layer <NUM> were obtained.

A conductive layer was formed on one surface of a peel film in the same way as in Example <NUM>, with the exception that in the polyurethane-based elastomer, the dendritic silver-coated copper powder was blended so that the filling factor of the silver-coated copper powder became <NUM> mass %, and that no mixed solvent was used. After the conductive layer was cut to a predetermined size, the peel film was peeled from the conductive layer. In this way, samples a1, a2, and a3 of the stretchable conductive layer <NUM> were obtained.

In a polyurethane-based elastomer (NE-<NUM> manufactured by Dainichiseika Color & Chemicals Mfg. ), a dendritic silver-coated copper powder with an average grain size of <NUM> (manufactured by MITSUI MINING & SMELTING CO. ) was blended such that the filling factor of the silver-coated copper powder (filling factor of the conductive filler in the conductive composition) became <NUM> mass %. Then, to <NUM> parts by mass of the polyurethane-based elastomer, <NUM> parts by mass of a mixed solvent of isopropyl alcohol and toluene (isopropyl alcohol to toluene weight ratio <NUM>:<NUM>) was added and stirred using a planetary mixer. In this way, a solution containing the polyurethane-based elastomer, the silver-coated copper powder, and organic solvent (hereinafter referred to as "conductive solution") was obtained.

After the conductive layer was cut to a predetermined size, the peel film was peeled from the conductive layer. In this way, samples d1 and d3 of the stretchable conductive layer <NUM> were obtained.

A conductive layer was formed on one surface of a peel film in the same way as in Example <NUM> with the exception that the conductive solution was applied to the one surface of the peel film so that the film thickness after drying became <NUM>. After the conductive layer was cut to a predetermined size, the peel film was peeled from the conductive layer. In this way, samples e1 and e3 of the stretchable conductive layer <NUM> were obtained.

In a polyurethane-based elastomer (NE-<NUM> manufactured by Dainichiseika Color & Chemicals Mfg. ), a dendritic silver powder (manufactured by MITSUI MINING & SMELTING CO. ) with an average grain size of <NUM> was blended such that the filling factor of the silver powder (filling factor of the conductive filler in the conductive composition) became <NUM> mass %. Then, with respect to <NUM> parts by mass of the polyurethane-based elastomer, <NUM> parts by mass of a mixed solvent of isopropyl alcohol and toluene (isopropyl alcohol to toluene weight ratio <NUM>:<NUM>) was added and stirred using a planetary mixer. In this way, a solution containing the polyurethane-based elastomer, the silver powder, and organic solvent (hereinafter referred to as "conductive solution") was obtained.

After the conductive layer was cut to a predetermined size, the peel film was peeled from the conductive layer. In this way, samples f1 and f3 of the stretchable conductive layer <NUM> were obtained.

A conductive layer was formed on one surface of a peel film in the same way as in Example <NUM>, with the exception that the conductive solution was applied to the one surface of the peel film so that the film thickness after drying became <NUM>. After the conductive layer was cut to a predetermined size, the peel film was peeled from the conductive layer. In this way, samples g1 and g3 of the stretchable conductive layer <NUM> were obtained.

Table <NUM> shows the filling factor of the conductive filler in each of the samples obtained as described above, and the length L, width W, and thickness T of the samples. <FIG> is a schematic diagram of the shape of each sample. As illustrated in <FIG>, the shape of each sample is rectangular band-like as viewed in plan. In <FIG>, L is the sample length, W is the sample width, and T is the sample thickness.

With respect to the samples a1, b1, c1, d1, e1, f1, and g1, a first evaluation experiment was conducted. In the first evaluation experiment, the samples were initially mounted to a home-built fatigue testing machine. Here, the home-built fatigue testing machine had a pair of acrylic plates of <NUM> centimeters square that was capable of executing reciprocating motion in opposite directions. Ends of the samples were respectively fastened to the surface of the acrylic plates, and the ends were further pinched by alligator clips and connected to an electric resistance measuring device. Then, the samples were maintained in natural state for <NUM> seconds. The period may be referred to as a first period P1. Thereafter, a <NUM>% tensile strain was applied to the samples repeatedly <NUM> times at a frequency of <NUM>. This period may be referred to as a second period P2. The second period P2 was <NUM> seconds. Finally, the samples were again maintained in natural state for <NUM> seconds. This period may be referred to as a third period P3. During each of these periods, the resistance between the ends of the samples was measured.

The <NUM>% tensile strain refers to a tensile strain such that the stretch rate r of the samples becomes <NUM>%. When the length of the sample before being stretched is L1, the length of the sample after being stretched is L2, and an increase in length L2 after a stretch with respect to the length L1 of the sample before being stretched is ΔL (= L2 - L1), the stretch rate r is expressed by the following expression (<NUM>).

The length L1 before stretch of the samples a1, b1, c1, d1, e1, f1, and g1 was <NUM>. Accordingly, when the <NUM>% tensile strain was applied, the length of the samples a1, b1, c1, d1, e1, f1, and g1 after a stretch became <NUM>.

<FIG>, <FIG>, and <FIG> show graphs illustrating the results of the first evaluation experiment. The broken curves A1, B1, and C1 of <FIG> respectively indicate changes in the resistance values of the samples a1, b1, and c1. <FIG> shows a part, enlarged, of <FIG> in a resistance value range of from <NUM>Ω to <NUM>Ω of the broken curves A1, B1, and C1. The broken curves D1, E1, F1, and G1 of <FIG> respectively indicate changes in the resistance values of the samples d1, e1, f1, and g1. The units of scale of the horizontal axis and the vertical axis in <FIG> are respectively the same as the units of scale of the horizontal axis and the vertical axis in <FIG>. In the graphs of <FIG>, <FIG>, and <FIG>, P1, P2, and P3 respectively indicate the first period P1, the second period P2, and the third period P3.

As will be understood from the graphs of <FIG>, <FIG>, and <FIG>, in the second period P2, the resistance values of samples a1, b1, c1, d1, e1, f1, and g1 became greater as the number of times of application of tensile strain was increased. When the periodic application of tensile strain to the samples a1, b1, c1, d1, e1, f1, and g1 was stopped, the resistance values of samples a1, b1, c1, d1, e1, f1, and g1 rapidly became smaller, and then gradually decreased (see the third period P3).

As will also be understood from the graphs of <FIG>, <FIG>, and <FIG>, in the second period P2, the resistance values of samples a1, b1, c1, d1, e1, f1, and g1 had different rates of increase. For example, as illustrated in <FIG> and <FIG>, with respect to sample a1, the resistance values at the start point of the second period P2 was <NUM>Ω, and the maximum value of resistance in the second period P2 was <NUM>Ω. With respect to sample b1, the resistance value at the start point of the second period P2 was <NUM>Ω, and the maximum value of resistance immediately before the end of the second period P2 was <NUM>Ω. With respect to sample c1, the resistance value at the start point of the second period P2 was <NUM>Ω, and the maximum value of resistance of the second period P2 was <NUM>Ω.

Thus, when the <NUM>% tensile strain was applied to the samples a1, b1, and c1 repeatedly <NUM> times at a frequency of <NUM>, the resistance value became <NUM>Ω or more in the case of sample a1, while in the case of sample b1 and sample c1, the resistance values became <NUM>Ω or less. Accordingly, it can be predicted that when the filling factor of the dendritic conductive filler in the conductive composition is not less than <NUM> mass % and not more than <NUM> mass %, the increase in resistance value upon application of the <NUM>% tensile strain repeatedly <NUM> times at a frequency of <NUM> will be reduced. It can also be predicted that when the filling factor of the dendritic conductive filler in the conductive composition is not less than <NUM> mass % and not more than <NUM> mass %, the increase in resistance value upon application of the <NUM>% tensile strain repeatedly <NUM> times at a frequency of <NUM> will be reduced more.

As illustrated in <FIG>, with respect to sample d1, the resistance value at the start point of the second period P2 was <NUM>Ω, and the maximum value of resistance in the second period P2 was <NUM>Ω. With respect to sample e1, the resistance value at the start point of the second period P2 was <NUM>Ω, and the maximum value of resistance in the second period P2 was <NUM>Ω. With respect to sample f1, the resistance value at the start point of the second period P2 was <NUM>Ω, and the maximum value of resistance in the second period P2 was <NUM>Ω. With respect to sample g1, the resistance value at the start point of the second period P2 was <NUM>Ω, and the maximum value of resistance in the second period P2 was <NUM>Ω. This indicates that, for the same thickness of the samples, the samples f1 and g1 using silver powder, compared with the samples d1 and e1 using silver-coated copper powder, have smaller rates of increase in resistance value in the second period P2 and smaller maximum values of resistance in the second period P2. In other words, when the samples have the same length and the same width, in order to make the maximum value of resistance in the second period P2 less than or equal to a predetermined value, the thickness of the stretchable conductive layer can be made thinner in samples f1 and g1 using silver powder than in samples d1 and e1 using silver-coated copper powder.

With respect to samples a2, b2, and c2, a second evaluation experiment was conducted. In the second evaluation experiment, first, the samples were maintained in natural state for <NUM> seconds. This period may be referred to as a first period P1. Then, a <NUM>% tensile strain was applied to the samples repeatedly <NUM> times at a frequency of <NUM>. This period may be referred to as a second period P2. The second period P2 was <NUM> seconds. Finally, the samples were again maintained in natural state for <NUM> seconds. This period may be referred to as a third period P3. During each of these periods, the resistance between the ends of the samples were measured.

<FIG> is a graph illustrating the results of the second evaluation experiment. In the graph of <FIG>, broken curves A2, B2, and C2 respectively indicate changes in the resistance values of samples a2, b2, and c2. Further, in the graph of <FIG>, P1, P2, and P3 respectively indicate the first period P1, the second period P2, and the third period P3. As will be understood from the graph of <FIG>, in the second period P2, the resistance values of the samples a2, b2, and c2 became greater as the number of times of application of tensile strain was increased. When the periodic application of tensile strain to the samples was stopped, the resistance values of the samples a2, b2, and c2 rapidly became smaller, and then gradually decreased (see the third period P3).

As will be understood from the graph of <FIG>, in the second period P2, the samples a2, b2, and c2 had different rates of increase in resistance value. Specifically, with respect to sample a2, the resistance value at the start point of the second period P2 was <NUM>Ω, and the maximum value of resistance in the second period P2 was <NUM>Ω or more (measurement limit). With respect to sample b2, the resistance value at the start point of the second period P2 was <NUM>Ω, and the maximum value of resistance in the second period P2 was <NUM>Ω. With respect to sample c2, the resistance value at the start point of the second period P2 was <NUM>Ω, and the maximum value of resistance in the second period P2 was <NUM>Ω.

That is, when the <NUM>% tensile strain was applied to the samples a2, b2, and c2 repeatedly <NUM> times at a frequency of <NUM>, the maximum value of resistance was <NUM>Ω or more in the case of sample a2, while the maximum value of resistance was not more than <NUM>Ω in the case of samples b2 and c2. Accordingly, it can be predicted that when the filling factor of the dendritic conductive filler in the conductive composition is not less than <NUM> wt% and not more than <NUM> wt%, the increase in resistance value upon application of a <NUM>% tensile strain repeatedly <NUM> times at a frequency of <NUM> will be decreased. Further, it can be predicted that when the filling factor of the dendritic conductive filler in the conductive composition is not less than <NUM> mass % and not more than <NUM> mass %, the increase in resistance value upon application of a <NUM>% tensile strain repeatedly <NUM> times at a frequency of <NUM> will be reduced more.

With respect to the samples a3, b3, c3, d3, e3, f3, and g3, a third evaluation experiment was conducted. The third evaluation experiment was conducted as follows. First, the resistance value between the ends of the samples before elongation was measured. Thereafter, the samples were elongated to a plurality of predetermined lengths, and the resistance value between the ends of the samples after elongation was measured. The measurement of the resistance value was performed in an elongation rate range of from <NUM>% to <NUM>% with respect to a plurality of kinds of elongation rates varying at <NUM>% intervals.

Table <NUM> shows the results of the third evaluation experiment with respect to sample a3. Table <NUM> shows the results of the third evaluation experiment with respect to sample b3. Table <NUM> shows the results of the third evaluation experiment with respect to sample c3. Table <NUM> shows the results of the third evaluation experiment with respect to sample d3. Table <NUM> shows the results of the third evaluation experiment with respect to sample e3. Table <NUM> shows the results of the third evaluation experiment with respect to sample f3. Table <NUM> shows the results of the third evaluation experiment with respect to sample g3.

<FIG>, <FIG>, and <FIG> are graphs illustrating the results of the third evaluation experiment. In the graph of <FIG>, broken curves A3, B3, C3, D3, E3, F3, and G3 respectively indicate the resistance values relative to elongation rate of the samples a3, b3, c3, d3, e3, f3, and g3. <FIG> is a graph only illustrating B3, D3, and E3 among the broken curves A3 to G3 in <FIG>. <FIG> is a graph only illustrating D3, E3, F3, and G3 among the broken curves A3 to G3 in <FIG>.

In Table <NUM> to Table <NUM>, the length L1 indicates the lengths of the samples before elongation. The length L1 of the samples a3, b3, c3, d3, e3, f3, and g3 before elongation was <NUM>. The length L2 indicates the lengths of the samples after elongation. The stretch rate r is the values computed based on the expression (<NUM>). The resistance value R1 indicates the resistance values of the samples before elongation. The resistance value R2 indicates the resistance values of the samples after elongation.

As illustrated in <FIG>, <FIG>, and <FIG>, in all of the samples a3, b3, c3, d3, e3, f3, and g3, the resistance value R2 when stretched at the stretch rate of <NUM>% was not more than <NUM>Ω. In this way, it will be seen that the conductive compositions according to Examples <NUM> to <NUM> are stretchable and able to suppress an increase in resistivity when stretched. In addition, as illustrated in <FIG>, the sample c3 became severed when stretched at the stretch rate of <NUM>%, resulting in a non-conducting state (see also Table <NUM>). The sample a3, when stretched at the stretch rate of <NUM>%, did not become severed but resulted in a non-conducting state (see also Table <NUM>). On the other hand, the samples b3, d3, e3, f3, and g3, as illustrated in <FIG>, <FIG>, and <FIG>, did not result in a non-conducting state even when stretched at the stretch rate of <NUM>%. The resistance value R2 of the samples b3, d3, e3, f3, and g3 when stretched at the stretch rate of <NUM>% was <NUM>Ω, <NUM>Ω, <NUM>Ω, <NUM>Ω, and <NUM>Ω, respectively (see also Table <NUM> to Table <NUM>).

Thus, it can be predicted that when the filling factor of the conductive filler in the conductive composition is not less than <NUM> mass % and not more than <NUM> mass %, the stretch properties will be enhanced and it will become possible to suppress an increase in resistance value upon elongation. Also, it can be predicted that when the filling factor of the conductive filler in the conductive composition is not less than <NUM> mass % and not more than <NUM> mass %, the stretch properties will be more enhanced and it will become possible to suppress an increase in resistance value upon elongation even more. Further, it can be predicted that when the filling factor of the conductive filler in the conductive composition is not less than <NUM> mass % and not more than <NUM> mass %, the stretch properties will become extremely high and it will become possible to more effectively suppress an increase in resistance value upon elongation.

It is also seen from <FIG> that the smaller the thickness of the samples, the higher the resistance value R2 becomes when stretched at the stretch rate of <NUM>%. It is also seen that, from a comparison of the broken curves D3 and F3 and a comparison of the broken curves E3 and G3 in <FIG>, when the thicknesses of the samples are the same, the resistance value R2 when stretched at the stretch rate of <NUM>% becomes lower if a silver powder is used as the conductive filler than if a silver-coated copper powder is used.

In the foregoing Examples <NUM> to <NUM>, as the elastomer, PANDEX 372E manufactured by DIC corporation or NE-<NUM> manufactured by Dainichiseika Color & Chemicals Mfg. As the elastomer, NE-<NUM>, MAU-<NUM>, NE-302HV, CU-<NUM> and the like manufactured by Dainichiseika Color & Chemicals Mfg. , Ltd may also be used.

<FIG> are process diagrams illustrating a method for manufacturing the stretchable conductive film <NUM>.

First, as illustrated in <FIG>, the stretchable conductive layer <NUM> is formed on one surface of the first peel film <NUM>, fabricating a first laminated film <NUM>.

Then, as illustrated in <FIG>, the hot-melt adhesive agent layer <NUM> is formed on one surface of the second peel film <NUM>, fabricating a second laminated film <NUM>.

Finally, as illustrated in <FIG>, the surface of the first laminated film <NUM> on the side of the stretchable conductive layer <NUM> and the surface of the second laminated film <NUM> on the side of the hot-melt adhesive agent layer <NUM> are laminate-adhered to each other. In this way, the stretchable conductive film <NUM> is obtained.

<FIG> are process diagrams illustrating another method for manufacturing the stretchable conductive film <NUM>.

First, as illustrated in <FIG>, the stretchable conductive layer <NUM> is formed on one surface of the first peel film <NUM>.

Then, as illustrated in <FIG>, the hot-melt adhesive agent layer <NUM> is formed on the surface of the stretchable conductive layer <NUM> on the opposite side from the first peel film <NUM> side.

Finally, as illustrated in <FIG>, the second peel film <NUM> is attached to the surface of the hot-melt adhesive agent layer <NUM> on the opposite side from the stretchable conductive layer <NUM> side. In this way, the stretchable conductive film <NUM> is obtained.

With reference to <FIG>, a method for using the stretchable conductive film <NUM> will be described.

First, the stretchable conductive film <NUM> is cut to a shape in accordance with the purpose of use.

Then, as illustrated in <FIG>, the second peel film <NUM> is peeled from the stretchable conductive film <NUM>.

Thereafter, as illustrated in <FIG>, the stretchable conductive film <NUM> from which the second peel film <NUM> has been peeled (which may be hereinafter referred to as "stretchable conductive film <NUM>") is placed on a textile fabric <NUM> in such a way that the surface of the stretchable conductive film <NUM> on the side of the hot-melt adhesive agent layer <NUM> opposes the textile fabric <NUM>. Then, an iron or the like is used to thermally bond the stretchable conductive film <NUM> onto the textile fabric <NUM>.

Thereafter, as illustrated in <FIG>, the first peel film <NUM> is peeled from the stretchable conductive film <NUM>. In this way, as illustrated in <FIG>, the stretchable conductive film <NUM> comprising the stretchable conductive layer <NUM> and the hot-melt adhesive agent layer <NUM> (which may be hereinafter referred to as "stretchable conductive film <NUM>") is placed in a state of being attached to the textile fabric <NUM>.

The stretchable conductive film <NUM> is used as an electrode and wiring material for biometric information measurement, such as electrocardiographic measurement and myoelectric measurement.

<FIG> is a schematic diagram illustrating an example in which the stretchable conductive film <NUM> is used as an electrode and wiring material for electrocardiographic measurement.

A shirt <NUM> made of a stretchy fabric has an electrocardiographic measurement wiring pattern configured from the stretchable conductive film <NUM> attached to the back surface of the front side thereof. The electrocardiographic measurement wiring pattern includes a first wiring <NUM>, a second wiring <NUM>, and a third wiring <NUM>. The wirings <NUM>, <NUM>, and <NUM> respectively include electrode portions 61a, 62a, and 63a; terminal portions 61b, 62b, and 63b; and wiring portions 61c, 62c, and 63c connecting the electrode and terminal portions. The electrode portions 61a, 62a, and 63a are the portions that contact the human body, and constitute electrocardiographic measurement electrodes. The electrode portions 61a and 62a of the first wiring <NUM> and second wiring <NUM> are disposed in positions corresponding to the chest on the back surface of the front side of the shirt <NUM>. The electrode portion 63a of the third wiring <NUM> is disposed in a position corresponding to the flank on the back surface of the front side of the shirt <NUM>. The terminal portions 61b, 62b, and 63b constitute terminals for connecting the wirings <NUM>, <NUM>, and <NUM> to an electrocardiograph. The terminal portions 61b, 62b, and 63b are disposed at the lower end on the back surface of the front side of the shirt <NUM>.

To the back surface of the front side of the shirt <NUM>, elongated stretchable protection films <NUM> are attached, the films covering the wiring portions 61c, 62c, and 63c of the respective wirings <NUM>, <NUM>, and <NUM>. The stretchable protection films <NUM> serve to insulate the surfaces (stretchable conductive layer <NUM>) of the wiring portions 61c, 62c, and 63c, and to prevent the development of scratches (damage) on the surfaces (stretchable conductive layer <NUM>) of the wiring portions 61c, 62c, and 63c. As the foregoing stretchable protection films <NUM>, the elastomer used in the stretchable conductive layer <NUM> that is filled with carbon black, for example, may be used. The stretchable protection films <NUM> may similarly include additives such as a plasticizer, a processing aid, a cross-linker, a vulcanization accelerator, a vulcanization aid, an anti-oxidant, a softener, and a coloring agent.

<FIG> is a schematic diagram illustrating an example in which the stretchable conductive film <NUM> is used as an electrode and wiring material for electromyographic measurement.

To the back surface (inner peripheral surface) of an arm cover <NUM> worn on the forearm, a wiring pattern for electromyographic measurement configured from the stretchable conductive film <NUM> is attached. The arm cover <NUM> is made of a stretchy fabric. The wiring pattern for electromyographic measurement includes a first wiring <NUM>, a second wiring <NUM>, and a third wiring <NUM>. The wirings <NUM>, <NUM>, and <NUM> respectively include electrode portions 71a, 72a, and 73a; terminal portions 71b, 72b, and 73b; and wiring portions 71c, 72c, and 73c connecting the electrode and terminal portions. The electrode portions 71a, 72a, and 73a are the portions that contact the human body, and constitute electromyographic measurement electrodes. The electrode portions 71a, 72a, and 73a are disposed in positions corresponding to the forearm muscle portion on the back surface of the arm cover <NUM>. The terminal portions 71b, 72b, and 73b constitute terminals for connecting the wirings <NUM>, <NUM>, and <NUM> to the electromyograph. The terminal portions 71b, 72b, and 73b are disposed at one end of the arm cover <NUM>.

To the back surface of the arm cover <NUM>, elongated stretchable protection films <NUM> are attached, the films covering the wiring portions 71c, 72c, and 73c of the respective wirings <NUM>, <NUM>, and <NUM>. The stretchable protection films <NUM> are made from the same material as the stretchable protection films <NUM>.

A plurality of kinds of samples of the stretchable conductive film <NUM> was fabricated. The samples were attached to a stretchy fiber fabric by the method described with reference to <FIG>. In this way, a plurality of kinds of test samples h, i, and j was fabricated. The stretchable conductive film <NUM> was attached to the stretchy fiber fabric by thermal bonding using an iron at <NUM>. The test samples h, i, and j were subjected to an evaluation test. The content and evaluation results of the evaluation test will be described.

<FIG> is a plan view diagrammatically illustrating the configuration of the test samples. <FIG> is a front view diagrammatically illustrating the configuration of the test samples.

Each of the test samples h, i, and j included a stretchy fiber fabric <NUM> which was rectangular as viewed in plan, and a stretchable conductive film <NUM>(<NUM>). The stretchable conductive film <NUM>(<NUM>) was attached to a surface central portion of the stretchy fiber fabric <NUM>, and was rectangular as viewed in plan. The stretchable conductive film <NUM> attached to the stretchy fiber fabric <NUM> included the hot-melt adhesive agent layer <NUM> on the stretchy fiber fabric <NUM> side, and the stretchable conductive layer <NUM> formed on the hot-melt adhesive agent layer <NUM>.

In the test samples h, i, and j, the stretchy fiber fabric <NUM> had the same shape, size, material and the like. The stretchy fiber fabric <NUM> had a length L1 of <NUM> and a width W1 of <NUM>. The stretchy fiber fabric <NUM> had a thickness of <NUM>.

The test samples h, i, and j had the same planar shape and size of the stretchable conductive film <NUM>. The stretchable conductive film <NUM> had a length L2 of <NUM> and a width W2 of <NUM>. As viewed in plan, an interval D1 between the long sides of the stretchy fiber fabric <NUM> and the corresponding long sides of the stretchable conductive film <NUM> was <NUM>. An interval D2 between the short sides of the stretchy fiber fabric <NUM> and the corresponding short sides of the stretchable conductive film <NUM> was <NUM>.

In the test samples h, i, and j, the conductive composition of the stretchable conductive layer <NUM> had the same material and thickness. Specifically, the conductive filler was a dendritic silver-coated copper powder with an average grain size of <NUM> (manufactured by MITSUI MINING & SMELTING CO. The filling factor of the silver-coated copper powder (filling factor of the conductive filler in the conductive composition) was <NUM> mass %. The elastomer was a polyurethane-based elastomer (NE-<NUM> manufactured by Dainichiseika Color & Chemicals Mfg. The stretchable conductive layer <NUM> had a thickness of <NUM>.

In the test samples h, i, and j, the material of the hot-melt adhesive agent layer <NUM> was the same. However, the hot-melt adhesive agent layer <NUM> had different thicknesses. The hot-melt adhesive agent layer <NUM> was a thermoplastic polyurethane (SHM101-PUR manufactured by Sheedom Co. , melting point <NUM>, durometer hardness 75A, and rupture elongation <NUM>%). The test sample h had a thickness of <NUM>. The test sample i had a thickness of <NUM>. The test sample j had a thickness of <NUM>.

Three each of the test samples h, i, and j were fabricated. The test samples were individually subjected to the evaluation test. During the evaluation test, one end of the test sample was fixed, and the other end was pulled at a constant speed (<NUM>/sec in the present example). At constant time intervals, the stretch rate (%) of the test sample and the resistance value (Ω) between the ends of the stretchable conductive film <NUM> were measured. The central value of the time-based resistance values of the three test samples h was considered as the time-based resistance value of the test sample h. The central value of the time-based resistance values of the three test samples i was considered as the time-based resistance value of the test sample i. The central value of the time-based resistance values of the three test samples j was considered as the time-based resistance value of the test sample j.

<FIG> is a graph illustrating the results of the evaluation test with respect to the test samples. In <FIG>, the curved lines H, I, and J indicate changes in the resistance values of the test samples h, i, and j.

It will be seen from the graph that as the thickness of the hot-melt adhesive agent layer <NUM> increased, the maximum stretch rate of the stretchable conductive film <NUM> became smaller and the resistance value relative to the stretch rate of the stretchable conductive film <NUM> became smaller.

A stretchable conductive film <NUM> not according to the invention includes the first peel film <NUM>, the stretchable conductive layer <NUM>, the hot-melt adhesive agent layer <NUM>, and the second peel film <NUM>. The hot-melt adhesive agent layer is formed on one surface of the stretchable conductive layer.

In the following, the configurations of the stretchable conductive film will be described with reference to <FIG>.

<FIG> is a cross sectional view illustrating the configuration of the stretchable conductive film not according to the invention. The stretchable conductive film 1A includes the stretchable conductive layer <NUM>, the hot-melt adhesive agent layer <NUM>, and the peel film <NUM>. The hot-melt adhesive agent layer <NUM> is formed on one surface of the stretchable conductive layer <NUM>. The peel film <NUM> is formed on the surface of the hot-melt adhesive agent layer <NUM> on the opposite side from the stretchable conductive layer <NUM> side.

<FIG> is a cross sectional view illustrating the configuration of the stretchable conductive film not according to the invention. The stretchable conductive film 1B includes the stretchable conductive layer <NUM>, the hot-melt adhesive agent layer <NUM>, and the peel film <NUM>. The hot-melt adhesive agent layer <NUM> is formed on one surface of the stretchable conductive layer <NUM>. The peel film <NUM> is formed on the surface of the stretchable conductive layer <NUM> on the opposite side from the hot-melt adhesive agent layer <NUM> side.

<FIG> is a cross sectional view illustrating the configuration of the stretchable conductive film according to the present invention. The stretchable conductive film 1C includes the stretchable conductive layer <NUM>, the hot-melt adhesive agent layer <NUM>, a stretchable protection layer <NUM>, and a peel film <NUM>. The hot-melt adhesive agent layer <NUM> is formed on one surface of the stretchable conductive layer <NUM>. The stretchable protection layer <NUM> is formed in at least a part on the surface of the stretchable conductive layer <NUM> on the opposite side from the hot-melt adhesive agent layer <NUM> side. The peel film <NUM> is formed on the surface of hot-melt adhesive agent layer <NUM> on the opposite side from the stretchable conductive layer <NUM> side. The stretchable protection layer <NUM> serves to insulate a part or all of the surface of the stretchable conductive layer <NUM> on the opposite side from the hot-melt adhesive agent layer <NUM> side. The stretchable protection layer <NUM> also serves to prevent the development of scratches (damage) in a part or all of the surface of the stretchable conductive layer <NUM> on the opposite side from the hot-melt adhesive agent layer <NUM> side. As the stretchable protection layer <NUM>, the elastomer used in the stretchable conductive layer <NUM> that is filled with carbon black, for example, may be used. The stretchable protection layer <NUM> may similarly include an additive such as a plasticizer, a processing aid, a cross-linker, a vulcanization accelerator, a vulcanization aid, an anti-oxidant, a softener, and a coloring agent.

<FIG> is a cross sectional view illustrating the configuration of the stretchable conductive film not according to the invention. The stretchable conductive film 1D includes the stretchable conductive layer <NUM>, the hot-melt adhesive agent layer <NUM>, the stretchable protection layer <NUM>, and a peel film <NUM>. The hot-melt adhesive agent layer <NUM> is formed on one surface of the stretchable conductive layer <NUM>. The stretchable protection layer <NUM> is formed in at least a part of the surface of the stretchable conductive layer <NUM> on the opposite side from the hot-melt adhesive agent layer <NUM> side. The peel film <NUM> is formed on the surface of the stretchable conductive layer <NUM> on the opposite side from the hot-melt adhesive agent layer <NUM> side so as to cover the stretchable protection layer <NUM>.

<FIG> is a cross sectional view illustrating the configuration of the stretchable conductive film according to the present invention. The stretchable conductive film 1E comprises the stretchable conductive layer <NUM>, the hot-melt adhesive agent layer <NUM>, the stretchable protection layer <NUM>, a first peel film <NUM>, and a second peel film <NUM>. The hot-melt adhesive agent layer <NUM> is formed on one surface of the stretchable conductive layer <NUM>. The stretchable protection layer <NUM> is formed in at least a part of the surface of the stretchable conductive layer <NUM> on the opposite side from the hot-melt adhesive agent layer <NUM> side. The first peel film <NUM> is formed on the surface of the stretchable conductive layer <NUM> on the opposite side from the hot-melt adhesive agent layer <NUM> side so as to cover the stretchable protection layer <NUM>. The second peel film <NUM> is formed on the surface of the hot-melt adhesive agent layer <NUM> on the opposite side from the stretchable conductive layer <NUM> side.

<FIG> is a cross sectional view illustrating a use state of the stretchable conductive film 1E.

When the stretchable conductive film 1E is used, first, the stretchable conductive film 1E is cut to a shape in accordance with the purpose of use. Then, the second peel film <NUM> is peeled from the stretchable conductive film 1E. Thereafter, the stretchable conductive film 1E from which the second peel film <NUM> has been peeled is placed on the textile fabric <NUM> in such a way that the surface of the stretchable conductive film on the side of the hot-melt adhesive agent layer <NUM> opposes the textile fabric <NUM>. Then, an iron or the like is used to thermally bond the stretchable conductive film 1E onto the textile fabric <NUM>. Thereafter, the first peel film <NUM> is peeled from the stretchable conductive film 1E. In this way, as illustrated in <FIG>, the stretchable conductive film 1E (indicated by the sign 12Ea in <FIG>) including the stretchable protection layer <NUM>, the stretchable conductive layer <NUM>, and the hot-melt adhesive agent layer <NUM> is placed in a state of being attached to the textile fabric <NUM>.

<FIG> is a cross sectional view illustrating a use state of the stretchable conductive film 1E. In this state, the stretchable protection layer <NUM> is formed in only a part of the surface of the stretchable conductive layer <NUM>. When the stretchable protection layer <NUM> is formed in only a part of the surface of the stretchable conductive layer <NUM>, as illustrated in <FIG>, the stretchable conductive film IE (indicated by the sign 12Eb in <FIG>) including the stretchable conductive layer <NUM>, the stretchable protection layer <NUM> formed in only a part of one surface of the stretchable conductive layer <NUM>, and the hot-melt adhesive agent layer <NUM> formed on the other surface of the stretchable conductive layer <NUM> is placed in a state of being attached to the textile fabric <NUM>.

When the stretchable protection layer <NUM> is formed in only a part of the surface of the stretchable conductive layer <NUM>, the exposed stretchable conductive layer can be used as an electrode or wiring. The configuration in which the stretchable protection layer <NUM> is formed in only a part of the surface of the stretchable conductive layer <NUM> can be fabricated by cutting out the stretchable protection layer <NUM> that has been patterned on the stretchable conductive layer <NUM> in advance.

The configuration in which the stretchable protection film is formed in only a part of the surface of the stretchable conductive layer <NUM> can also be obtained by attaching the stretchable protection film onto a part of the stretchable conductive layer attached to the textile fabric via the hot-melt adhesive agent layer.

While the embodiments of the present invention have been described in detail, the embodiments are merely specific examples for illustrating the technical content of the present invention. It should be noted that the present invention is not to be interpreted as being limited to the specific examples, and that the scope of the present invention is limited only by the appended claims.

Claim 1:
A stretchable conductive film for textiles, comprising:
a stretchable conductive layer (<NUM>) having stretch properties;
a hot-melt adhesive agent layer (<NUM>) formed on one surface of the stretchable conductive layer (<NUM>);
a stretchable protection layer (<NUM>) having stretch properties and formed on at least
a part of a surface of the stretchable conductive layer (<NUM>) on an opposite side from the hot-melt adhesive agent layer (<NUM>) side, and
a peel film (<NUM>) is formed on the surface of hot-melt adhesive agent layer (<NUM>) on an opposite side from the stretchable conductive layer (<NUM>) side; wherein
the stretchable conductive layer is configured from a conductive composition including an elastomer and a conductive filler filling the elastomer, and wherein
the stretchable protection layer (<NUM>) includes the elastomer that is filled with carbon black.