JP7007988B2 - Conductive tape for observation - Google Patents

Description

The present invention relates to an observation conductive tape used for continuously collecting, for example, a section cut by a microtome and observing it as it is with an electron microscope or the like.

Conventionally, a microtome has been widely known as a device for producing a thin section sample used for physicochemical sample analysis or microscopic observation of a biological sample, etc., and reduces the burden on the operator of the thin section sample preparation work. At the same time, in order to reduce the decrease in the accuracy of the thin section sample, in Patent Document 1 (Japanese Patent Laid-Open No. 2004-28910) and Patent Document 2 (Japanese Patent Laid-Open No. 2000-275538), sliced samples are used as carrier tapes. It has been proposed to keep it in place.

This carrier tape requires that sections cut by microtome can be continuously collected without wrinkles, and that they can be observed as they are with an electron microscope, etc., that the surface resistance is stable and low, and that the collected sections are collected. It was necessary to be able to visually recognize the carrier tape, but the fact is that such a carrier tape has not yet been provided.

Japanese Unexamined Patent Publication No. 2004-28910 Japanese Unexamined Patent Publication No. 2000-275538

An object of the present invention is to provide an observation conductive tape having a small variation in observation.
Another object of the present invention is to provide an observation conductive tape in which the collected sections can be easily visually recognized in addition to the above-mentioned problems.

According to the present invention, it is a conductive tape in which a conductive layer is laminated on at least one side of a polymer film, and the conductive layer contains a three-dimensional crosslinked structure having an amide ester bond with carbon nanotubes, and the surface of the conductive layer. A conductive tape for observation having a water contact angle of less than 60 ° is provided.

Further, according to the present invention, as the preferred embodiment of the present invention, the metal alkoxide layer is provided between the polymer film and the conductive layer, and the visible light region (400 nm or more and 800 nm or less) seen from the conductive layer surface of the conductive tape. ) Has a first reflection bottom peak in the range of wavelength 475 nm or more and 650 nm or less, and the ratio of the maximum reflectance of the first reflection peak to the minimum reflectance in the reflection spectrum (maximum reflectance / minimum reflectance). The rate) is 1.2 times or more, and the transmitted color tones a * and b * in the CIE-Lab coloring method measured from the conductive layer surface of the conductive tape are the following equations (1) and (2), respectively.
-2.0 <a * <0.0 (1)
2.0 <b * <4.0 (2)
The surface resistance value of the conductive layer surface of the conductive tape is 100Ω / □ or more and 5,000Ω / □ or less, the metal alkoxide is alkoxysilane, and the carbon nanotubes contained in the conductive layer At least one of the following: the average diameter is in the range of 0.4 to 50 nm, the thickness of the polymer film is 12 μm or more and 75 μm or less, the conductive tape is the polymer film, and the observation is electron microscopic observation. Also provided is a conductive tape for observation.

According to the present invention, since a conductive layer containing a three-dimensional crosslinked structure having a carbon nanotube and an amide ester bond is used, the conductive characteristics are stable, cracks and disconnections are unlikely to occur even when bent, and flatness is also obtained. It can be maintained, and when a sliced sample is once floated in a water bath and then scooped up with a conductive tape immersed in the water bath, contamination of the water bath and deterioration of the conductive tape can be suppressed. It is very effective for observing continuously sliced samples without variation.

Further, according to the present invention, by providing the metal alkoxide layer between the polymer film and the conductive layer, the observation can be further stabilized, and the first reflection bottom peak is provided in the wavelength range of 475 to 650 nm. As a result, the visual visibility can be further improved.

It is a figure which shows the reflection spectroscopic spectrum of Example 2 of this invention, and the appearance of the cut piece on the conductive tape. It is a figure which shows the reflection spectroscopic spectrum of Example 3 of this invention, and the appearance of a cut piece on a conductive tape. It is a figure which shows the reflection spectroscopic spectrum of Example 4 of this invention, and the appearance of the cut piece on the conductive tape.

Generally, the conductive layer includes an inorganic conductive layer such as carbon or ITO for vacuum film formation, an organic conductive layer using a conductive polymer such as PEDOT-PSS, and a conductive layer such as a metal wire or carbon. There are various things such as a conductive layer in which a material is contained in a coating film.

However, the surface resistance value of the conductive layer formed by forming carbon in a vacuum is unstable, and ITO has a problem that ITO cracks during section recovery and ITO cracks are visible when observing with an electron microscope. There is a problem that the contrast of the electron microscope image is lowered due to the secondary electrons. In addition, the conductive polymer has a problem of being charged up when observed with an electron microscope, and since the conductive layer formed of silver nanowires has a mesh shape, it easily affects the electron microscope image, and the flatness of the conductive layer is poor. Easy to be damaged. Further, in the conductive layer using carbon nanotubes as a conductive material, the carbon nanotubes tend to fall off and the surface resistance tends to be unstable.

However, surprisingly, by using a conductive layer containing a three-dimensional crosslinked structure having a carbon nanotube and an amide ester bond, the conductive characteristics are stable, cracks and disconnections are less likely to occur even when bent, and flatness is achieved. It was also found that when the sample is continuously observed using the water bath, the contamination of the water bath and the deterioration of the conductive tape can be suppressed.

Moreover, by providing a metal alkoxide layer between the polymer film and the conductive layer, the effect can be further enhanced, and the reflection in the visible light region (400 nm or more and 800 nm or less) seen from the conductive layer surface of the conductive tape. It was also found that the presence of the first reflection bottom peak in the range of the wavelength of 475 nm or more and 650 nm or less in the spectrum is more excellent in visual visibility.

Therefore, as described above, the conductive tape for observation of the present invention preferably has a conductive layer containing a three-dimensional crosslinked structure having a carbon nanotube and an amide ester bond laminated on at least one side of the polymer film. It has a metal alkoxide layer between the polymer film and the conductive layer, and preferably has a wavelength of 475 nm or more and 650 nm or less in the reflection spectrum of the visible light region (400 nm or more and 800 nm or less) seen from the conductive layer surface of the conductive tape. It is characterized by having a first reflection bottom peak in the range, which will be described in detail below.

<Conductive layer>
In the conductive layer in the present invention, the conductive layer contains at least a three-dimensional crosslinked structure having an amide ester bond with carbon nanotubes.

The content of carbon nanotubes in the conductive layer can be appropriately adjusted according to a desired surface resistance value, the surface resistance value can be reduced by increasing the content, and the surface resistance value can be increased by reducing the content. The content of carbon nanotubes is preferably in the range of 1 to 30 mg / m ² , more preferably in the range of 2 to 20 mg / m ² , and particularly preferably in the range of 3 to 17 mg / m ² .

The total solid content coating amount of the conductive layer is preferably in the range of 2 to 90 mg / m ² , preferably in the range of 3 to 60 mg / m ² , and preferably in the range of 4 to 50 mg / m ² .

The thickness of the conductive layer is preferably in the range of 1 to 20 nm, more preferably in the range of 2 to 15 nm, and particularly preferably in the range of 3 to 10 nm.

The conductive layer can be formed by applying a coating liquid containing a carbon nanotube dispersion liquid by a wet coating method. Examples of the wet coating method include a cast coating method, a dip coating method, a spin coating method, a knife coating method, a kiss coating method, a roll coating method, a gravure coating method, a slot die coating method, and a bar coating method. Among these, the slot die coat method is preferably used.

The carbon nanotubes contained in the conductive layer are not particularly limited as long as they have a shape in which one single surface of graphite is substantially wound into a tubular shape, and a single layer in which one single surface of graphite is wound in one layer. Both carbon nanotubes and multi-walled carbon nanotubes wound in multiple layers can be applied.

As the carbon nanotubes, those having an average diameter of 0.3 to 20 nm and an average length of about 0.1 to 20 μm are preferably used. In particular, from the viewpoint of increasing the flatness of the conductive layer and reducing the surface resistance, it is preferable that the average diameter of the carbon nanotubes is 1 to 10 nm and the average length is 1 to 10 μm. From the viewpoint of maintaining a higher degree of flatness, it is preferable to use carbon nanotubes from which aggregates and the like have been removed by centrifugation or the like.

The carbon nanotube dispersion liquid preferably contains a carbon nanotube dispersant. As such a dispersant, an ionic dispersant having high dispersibility is preferably used. Examples of the ionic dispersant include anionic dispersants, cationic dispersants, and amphoteric dispersants. Among these ionic dispersants, anionic dispersants are preferably used because they are excellent in dispersibility and dispersion retention of carbon nanotubes. Among the anionic dispersants, carboxymethyl cellulose and salts thereof, such as sodium salts, ammonium salts, and polystyrene sulfonic acid salts, can efficiently disperse carbon nanotubes and disperse amide ester bonds described later. A dispersant having a carboxyl group is preferable because it can be formed by an agent, and carboxymethyl cellulose or a salt thereof is most preferable.

By the way, as described above, the conductive layer in the present invention is characterized by containing a three-dimensional crosslinked structure having an amide ester bond. In this three-dimensional crosslinked structure having an amide ester bond, for example, a carbon nanotube dispersion liquid contains a crosslinking agent having an oxazoline group and a dispersant having a carboxyl group, and the carbon nanotube dispersion liquid is applied onto a polymer substrate. When dried, the oxazoline group of the cross-linking agent and the carboxyl group of the dispersant undergo a reaction represented by the following chemical formula to form a three-dimensional cross-linked structure having an amide ester bond.

By containing the three-dimensional crosslinked structure having an amide ester bond in the conductive layer, the conductive layer can be fixed on the polymer film, and it is possible to prevent the conductive layer from peeling off when the microtome cut pieces are collected. Will be. This effect is very important for observing continuously sliced samples with an electron microscope, and if this elution is large, for example, the sliced sample is once floated in a water bath and then immersed in the water bath for conductivity. When trying to scoop up with a sex tape, the observation may vary due to contamination of the water bath or deterioration of the conductive tape. When the cross-linking agent and the dispersant are reacted to form a three-dimensional cross-linked structure having an amide ester bond, the amount of the cross-linking agent added is in the range of 1 to 100 parts by weight with respect to 100 parts by weight of the dispersant. It is preferable, and 10 to 50 parts by weight is more preferable. If the amount added is less than 1 part by weight, the elution of the dispersant cannot be suppressed, and if it is 100 parts by weight or more, the conductivity of the carbon nanotubes is likely to be impaired.

In the present invention, any cross-linking agent that forms an amide ester bond can be used without limitation to oxazoline, and other cross-linking agents that do not form an amide ester bond can also be used as long as the effects of the present invention are not impaired. As a specific other cross-linking agent, a cross-linking agent having an origin ring or a carboimide is generally known. However, the cross-linking agent having an origin ring has problems of toxicity and handling, and the cross-linking agent having carboimide has a problem that the reactivity in an acidic atmosphere is high and the carbon nanotube dispersion liquid is easily thickened and gelled.

The conductive layer in the present invention preferably contains a dispersant as described above in order to enhance the dispersibility of the carbon nanotubes, and the content of the dispersant does not deteriorate the conductivity (surface resistance value) of the carbon nanotubes. From the viewpoint of ensuring good dispersibility, the range of 50 to 1000 parts by mass is preferable, the range of 100 to 600 parts by mass is more preferable, and the range of 200 to 400 parts by mass is particularly preferable with respect to 100 parts by mass of carbon nanotubes. preferable.

Water is preferable as the dispersion medium used for preparing the carbon nanotube dispersion liquid from the viewpoints that the above-mentioned dispersant can be safely dissolved and that the waste liquid can be easily treated.

The carbon nanotube dispersion liquid is, for example, a mixing and dispersing machine of carbon nanotubes and a dispersant in a dispersion medium, for example, a ball mill, a bead mill, a sand mill, a roll mill, a homogenizer, an ultrasonic homogenizer, a high-pressure homogenizer, an ultrasonic device, an attritor, and a resolver. , Can be prepared by dispersing using a paint shaker or the like. These mixing / dispersing machines may be used alone, or a plurality of mixing / dispersing machines may be combined to perform stepwise dispersion.

The concentration of the carbon nanotubes at the time of dispersing the carbon nanotubes is preferably in the range of 0.003 to 0.15% by mass because the processing time at the time of dispersion can be shortened. The carbon nanotube dispersion liquid thus prepared is further diluted and adjusted to a predetermined concentration suitable for coating.

When applying the carbon nanotube dispersion liquid, alcohol or a surfactant can be contained in the carbon nanotube dispersion liquid in order to improve the coatability. Among these, alcohol is preferable, and for example, lower alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol and isopropyl alcohol are preferably used.

The contact of the conductive layer with water is preferably low, specifically, the contact angle with water is preferably 70 degrees or less, and more preferably 55 degrees or less. It is known that if the contact angle of the conductive layer with water is large, the cutting piece will be wrinkled when the microtome cutting piece is collected, making it difficult to observe the cutting piece with an electron microscope.

When the contact angle of the conductive layer with water is large, it is also possible to perform plasma treatment such as corona treatment or UV / ozone treatment so that the contact angle with water is within a predetermined range.

<Metal alkoxide layer>
As described above, the observation conductive tape of the present invention preferably has a metal alkoxide layer between the polymer film and the conductive layer. The metal alkoxide layer in the present invention is a layer composed of a metal alkoxide represented by the general formula of M (OR) n, in which M is a metal element, R is an alkyl group, and n is the oxidation number of the metal element. Means. Examples of M in the general formula include Si, Mg, Ge, Li, Na, Fe, Ga, Sb, Sn, Ta and the like, and among these, alkoxide silane having Si as a metal element is preferable.

The R portion of the general formula will be described by taking alkoxide silane as an example. For example, tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, and γ-glycidoxypropyltrimethoxy. Silane, β- (3,4 epoxycyclohexyl) ethyltrimethoxysilane, vinyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyldimethoxysilane, Examples thereof include γ-aminopropyltriethoxysilane.

It is preferable to use two or more kinds of these alkoxysilanes in a mixture from the viewpoints of mechanical strength, adhesion and solvent resistance of the layer, and particularly from the viewpoint of solvent resistance, the weight of the alkoxysilanes in the entire composition. It is preferable that the alkoxysilane having an amino group is contained in the molecule in the range of 0.5 to 40%. Particularly preferred is the combined use of γ-glycidoxypropyltrimethoxylane and methyltrimethoxysilane.

Alkoxysilane may be used as a monomer or may be hydrolyzed and dehydrated and condensed in advance to form an appropriate oligomer, but usually, a coating liquid dissolved and diluted in an appropriate organic solvent is applied onto the substrate. .. The coating film formed on the substrate is hydrolyzed by moisture in the air or the like, and then crosslinked by dehydration condensation.

In general, an appropriate heat treatment is required to promote cross-linking, and it is preferable to perform a heat treatment at a temperature of 100 ° C. or higher for several minutes or longer in the coating step. In some cases, the degree of cross-linking can be further increased by irradiating the coating film with active rays such as ultraviolet rays in parallel with the heat treatment.

As the diluting solvent, alcohol-based or hydrocarbon-based solvents such as ethanol, isopropyl alcohol, butanol, 1-methoxy-2-propanol, hexane, cyclohexane, ligroin and the like are preferable. In addition, polar solvents such as xylene, toluene, cyclohexanone, methyl isobutyl ketone, and isobutyl acetate can also be used. These can be used alone or as a mixed solvent of two or more kinds.

Further, for the coating, a method using a known coating machine such as a doctor knife, a bar coater, a gravure roll coater, a curtain coater, a knife coater, a spin coater, a spray method, a dipping method and the like are used.

Since the metal alkoxide layer thus obtained can easily prevent wrinkles from forming in the cutting piece when the cutting piece of the microtome is collected, it is preferable to further make the surface hydrophilic. As a method for hydrophilizing the metal alkoxide layer, a method of mixing a resin containing a hydroxyl group or a method of adding a resin having a quaternary ammonium salt or a surfactant can be adopted.

By the way, in the metal alkoxide layer in the present invention, a cross-linking agent having a cardiboimide group or an oxozarin group can be added to the metal alkoxide solution in order to further improve the adhesion to the conductive layer. This is because the carboxyl group for forming the three-dimensional crosslinked structure having an amide ester bond contained in the conductive layer reacts with the crosslinking agent to improve the adhesion. When a carbodiimide group present in the metal alkoxide layer is present, an N-acylurea is formed, and when an oxozarin group is present, an amide ester bond is formed. That is, the cross-linking agent added to the metal alkoxide layer reacts with the resin component having a carboxyl group contained in the conductive layer to form a bond thereof, thereby further improving the adhesion between the metal alkoxide layer and the conductive layer. Can be made to.

The ratio of the cross-linking agent for forming the metal alkoxide layer is 1 to 100 parts by weight, more preferably 1 to 50 parts by weight, of the cross-linking agent having a carbodiimide group or an oxozarin group with respect to 100 parts by weight of the metal alkoxide. If an excessive amount of the cross-linking agent is added, a large amount of the unreacted cross-linking agent will be present in the metal alkoxide layer, and the adhesion tends to be lowered.

<Optical characteristics>
The observation conductive tape of the present invention has a wavelength range of 475 nm or more and 650 nm or less, more preferably 485 nm or more and 640 nm or less in the reflection spectrum of the visible light region (400 nm or more and 800 nm or less) seen from the conductive layer surface. It is particularly preferable to have the first reflection peak in the range of 490 nm or more and 630 nm or less. By setting the first reflection peak in this region, the reflection color tone of the conductive tape becomes bluish, which makes it easier to visually recognize the microtome cutting pieces deposited on the conductive tape. From such a viewpoint, it is preferable that the ratio (maximum reflectance / minimum reflectance) of the maximum reflectance of the first reflection peak to the minimum reflectance in the reflection spectrum is 1.2 times or more.

It is preferable that the transmitted color tones a * and b * in the CIE-Lab coloring method measured from the surface of the conductive tape on the low surface resistance layer side in the present invention satisfy the following formulas (1) and (2), respectively. ..
-2.0 <a * <0.0 (1)
2.0 <b * <4.0 (2)
More preferable a * and b * are
-1.0 <a * <0.0 (1')
2.5 <b * <4.0 (2')
Is in the range of.

The surface resistance value of the conductive layer surface of the conductive tape in the present invention is 100Ω / □ or more and 5,000Ω / □ or less because it is easy to prevent wrinkles from forming in the cutting piece when collecting the cutting piece of the microtome. It is preferable that it is 200 Ω / □ or more, 3,000 Ω / □ or less, and particularly preferably 500 Ω / □ or more and 1500 Ω / □ or less.

As described above, the conductive tape for observation of the present invention preferably includes a conductive layer / metal alkoxide layer (laminated form 1) or a metal alkoxide layer / conductive layer (laminated form 2) when viewed from the polymer film side. .. The above-mentioned laminated forms 1 and 2 have an advantage that the surface resistance can be more easily suppressed because the conductive layer is on the surface. From such a viewpoint, the surface resistance value of the conductive layer is preferably 250 Ω / □ or more and 2000 Ω / □ or less.

<Polymer film>
As the polymer film in the present invention, a known polymer film can be adopted, and the polymer film is not particularly limited. Examples of resins that form polymer films include polyester resins, polypropylene resins, polyolefin resins such as polyethylene films, polylactic acid resins, polycarbonate resins, acrylic resins such as polymethacrylate resins and polystyrene resins, and polyamide resins such as nylon resins. Examples thereof include a polyvinyl chloride resin, a polyurethane resin, a fluororesin, and a polyphenylene resin, which may be a homopolymer, a copolymer polymer, or a mixture of a plurality of resins.

Typical examples of polymer films include polyethylene terephthalate films, polyester films such as polyethylene naphthalenedicarboxylate films and polylactic acid films, polyolefin films such as polypropylene films and polyethylene films, and acrylic films such as polycarbonate films and polymethacrylate films. Examples thereof include polyamide films such as nylon, polyvinyl chloride films, polyurethane films, fluorofilms, polyphenylene sulfide films, and polystyrene films. Among these, a polymer film having a carboxyl group is preferable from the viewpoint of further enhancing the adhesion between the conductive layer and the metal alkoxide layer.

Of these, polyester film, polycarbonate film, etc. are preferable in terms of mechanical properties, dimensional stability, transparency, etc., and polyethylene terephthalate film and polyethylene naphthalenedibox carboxylate film are also preferable in terms of mechanical strength, versatility, etc. Is preferable, and polyethylene-2,6-naphthalenedicarboxylate film is particularly preferable.

The thickness of the polymer film is not particularly limited as long as it can secure flexibility when formed into a tape and has excellent handleability, but is preferably 12 μm or more, and preferably 75 μm or less. The lower limit of the thickness of the preferable polymer film is 20 μm, further 30 μm. A more preferable upper limit of the thickness of the polymer film is 70 μm, further 60 μm. Further, the polymer film may be a composite film produced by coextrusion, or may be a film obtained by laminating the obtained films by various methods. Further, in order to improve the adhesion to the above-mentioned low surface resistance layer, an easy-adhesion layer may be separately formed on the surface.

[Application example of conductive tape]
The conductive tape of the present invention can be used as a carrier tape for continuously preparing a sample with a microtome or the like and transporting the sample so that it can be observed with an electron microscope or the like.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited thereto. The various measured values in the present invention are measured by the following methods, and parts and% mean parts by weight and% by weight, respectively, unless otherwise specified.
(1) Measurement of surface resistance value (Ω / □)
The surface resistance value of the conductive layer of the conductive tape was measured using Loresta AX MCP-T370 (4 probe method) manufactured by Mitsubishi Chemical Corporation. The measurement environment is 23 ° C. and a relative humidity of 55%.
(2) Measurement of the thickness of each layer
The measurement was performed by observing the cross section of the conductive tape with a transmission electron microscope (TEM). The observation was performed by selecting a magnification at which the thickness of each layer was within 50% in the vertical direction within one visual field.
(3) Contact angle of water The water contact angle on the surface of the conductive layer of the conductive tape was measured using a contact angle meter Model CA-X manufactured by Kyowa Interface Science Co., Ltd.
(4) Reflection spectroscopic spectrum The reflection spectroscopic spectrum was measured from the conductive layer surface side of the conductive tape using a Spectrophotometer U-4000 manufactured by Hitachi, Ltd.
(5) Transmission color tone The transmission color tone was measured by arranging the conductive layer surface side of the conductive tape on the light receiving side using SE-6000 manufactured by Nippon Denshoku Co., Ltd.
(6) Average diameter and average length of carbon nanotubes The average diameter and average length of carbon nanotubes were measured by observation with a transmission electron microscope (TEM). Specifically, 50 carbon nanotubes were arbitrarily selected, their outer diameters and lengths were measured, and the average values thereof were taken as the average diameter and the average length.

(7) Preparation of metal alkoxide (alkoxysilane) solution γ-glycidoxypropyltrimethoxylan (“KBM403” manufactured by Shin-Etsu Chemical Industry Co., Ltd.) and methyltrimethoxysilane (“KBM13” manufactured by Shin-Etsu Chemical Industry Co., Ltd.) Was mixed at a molar ratio of 1: 1 and the alkoxysilane was hydrolyzed with an aqueous acetic acid solution (pH = 3.0) by a known method to obtain an alkoxysilane hydrolyzate 1. N-β (aminoethyl) γ-aminopropylmethoxysilane (“KBM603” manufactured by Shin-Etsu Chemical Co., Ltd.) was added at a ratio of 1 part by weight to 20 parts by weight of the solid content of the alkoxysilane hydrolyzate 1. Further, a mixed solution of isopropyl alcohol and n-butanol (weight ratio of isopropyl alcohol to n-butanol is 2: 1) is diluted so that the solid content concentration is 3 parts by weight with respect to 100 parts by weight of the solution, and the metal alkoxide solution is used. -Created A.
A cross-linking agent carbodilite SV-02 (manufactured by Nisshinbo Chemical Co., Ltd.) having a carbodiimide group was added to 100 parts by weight of the metal alkoxide solution-A to prepare a metal alkoxide solution-B.

(8) Dispersion of carbon nanotubes As the dispersion of carbon nanotubes, a commercially available carbon nanotube dispersion using carboxylmethylcellulose as a dispersant is prepared, and centrifugal separation is performed on the dispersion to form aggregates having a particle size of 5 μm or more. What was removed as much as possible was designated as carbon nanotube dispersion liquid-I. The content of carbon nanotubes in the carbon nanotube dispersion liquid-I was 0.1% by mass, the average diameter was less than 10 nm, the average length was less than 10 μm, and the dispersion liquid was water. To 100 parts by weight of the dispersion liquid, 1 part by weight of the cross-linking agent Evocross WS-700 (manufactured by Nippon Shokubai Co., Ltd.) having an oxazoline group was added to the carbon nanotube dispersion liquid after centrifugation. This was designated as carbon nanotube dispersion liquid-II.

(9) Appearance of the cutting piece A microtome cutting piece (epoxy resin, thickness about 30 μm) was placed on the prepared conductive tape, and the appearance of the cutting piece in the mounted state was observed and evaluated according to the following criteria. ..
A: The cutting piece could be easily observed visually.
B: It was difficult to visually confirm the cutting piece.

(10) Evaluation of the conductive tape as a carrier film Immerse the conductive tape in distilled water for 10 minutes and check for any change in appearance. Also, soak a cotton swab with distilled water and lightly rub the conductive layer surface side with a cotton swab 10 times to check for peeling of the conductive layer.
The above evaluation was performed, and the judgment was made according to the following criteria.
Good: No color unevenness due to peeling of the conductive layer, no coloring due to the conductive layer on the cotton swab Unusable: Color unevenness due to peeling of the conductive layer, or coloring due to the conductive layer is seen on the cotton swab

[Example 1]
As a polymer film, a polyester film manufactured by Teijin Film Solutions Co., Ltd. (trade name: Q65HW, substrate thickness 50 μm) was prepared, the above-mentioned carbon nanotube dispersion liquid-II was applied, and the film was dried at 140 ° C. for 5 minutes to form a conductive layer. Formed. The surface resistance value after forming the carbon nanotube layer was 1200 Ω / □.
The obtained conductive tape was immersed in distilled water for 10 minutes, but no particular change was observed in appearance.
The surface of the conductive layer was lightly rubbed with a cotton swab soaked in distilled water, but no peeling of the conductive layer was observed.

[Example 2]
As a polymer film, a polyester film manufactured by Teijin Film Solutions Co., Ltd. (trade name: Q65HW, substrate thickness 50 μm) was prepared, and the above-mentioned metal alkoxide solution −A was applied to one surface thereof at 130 ° C. for 2 minutes. It was dried to form the metal alkoxide layer-1. The above-mentioned carbon nanotube dispersion liquid-II was applied onto the metal alkoxide layer-1, and dried at 140 ° C. for 5 minutes to form a conductive layer. The surface resistance value after forming the carbon nanotube layer was 1050 Ω / □. Further, the reflection spectrum after forming the conductive layer is shown in FIG.
The obtained conductive tape was immersed in distilled water for 10 minutes, but no particular change was observed in appearance.
The surface of the conductive layer was lightly rubbed with a cotton swab soaked in distilled water, but no peeling of the conductive layer was observed.

[Example 3]
The same operation as in Example 1 was performed except that the metal alkoxide layer of Example 1 was replaced with the metal alkoxide solution −B, to prepare a conductive tape.
The obtained conductive tape was immersed in distilled water for 10 minutes, but no particular change was observed in appearance.
The surface of the conductive layer was lightly rubbed with a cotton swab soaked in distilled water, but no peeling of the conductive layer was observed.

[Comparative Example 1]
A conductive tape was prepared by performing the same operation as in Example 1 except that the carbon nanotube dispersion liquid was replaced with the carbon nanotube dispersion liquid-I.
The obtained conductive tape was immersed in distilled water, and it was confirmed that the thin film was peeled off from the surface of the conductive layer immediately after the immersion.
Further, when the conductive layer was lightly rubbed with a cotton swab soaked with distilled water, the conductive layer was easily peeled off.

[Comparative Example 2]
The same operation as in Example 2 was performed except that the carbon nanotube dispersion liquid was replaced with the carbon nanotube dispersion liquid-I, to prepare a conductive tape.
The obtained conductive tape was immersed in distilled water, and it was confirmed that the thin film was peeled off from the surface of the conductive layer immediately after the immersion.

[Example 4]
The same operation as in Example 2 was performed except that the film thickness of the metal alkoxide layer was changed, to prepare a conductive tape.
The reflection spectrum after the formation of the metal alkoxide layer on the polymer film is shown in FIG. 3, and the reflection spectrum after the formation of the conductive layer is shown in FIG.
The obtained conductive tape was immersed in distilled water for 10 minutes, but no particular change was observed in appearance.
The surface of the conductive layer was lightly rubbed with a cotton swab soaked in distilled water, but no peeling of the conductive layer was observed.
The characteristics of the obtained conductive tape are shown in Table 1.

The conductive tape of the present invention can be suitably used as a carrier tape for observing continuously sliced samples with an electron microscope or the like without variation.

Claims (10)

A conductive tape in which a conductive layer is laminated on at least one side of a polymer film, the conductive layer contains a three-dimensional crosslinked structure having an amide ester bond with carbon nanotubes, and the water contact angle of the surface of the conductive layer is 60 °. Conductive tape for observation, characterized by being less than. The observing conductive tape according to claim 1, which has a metal alkoxide layer between the polymer film and the conductive layer. The observational conductivity according to claim 2, wherein the first reflection bottom peak is provided in the wavelength range of 475 nm or more and 650 nm or less in the reflection spectrum of the visible light region (400 nm or more and 800 nm or less) seen from the conductive layer surface of the conductive tape. tape. The observing conductive tape according to claim 3, wherein the ratio (maximum reflectance / minimum reflectance) of the minimum reflectance of the first reflection bottom peak to the first reflection peak in the reflection spectrum is 1.2 times or more. Transmission color tones a * and b in the CIE-Lab coloring method measured from the conductive layer surface of the conductive tape.
* Is the conductive tape for observation according to claim 3, which satisfies the following formulas (1) and (2), respectively.
-2.0 <a * <0.0 (1)
2.0 <b * <4.0 (2) The observation conductive tape according to any one of claims 1 to 3, wherein the surface resistance value of the conductive layer surface of the conductive tape is 100 Ω / □ or more and 5,000 Ω / □ or less. The conductive tape for observation according to claim 2, wherein the metal alkoxide is alkoxysilane. The observation conductive tape according to any one of claims 1 to 3, wherein the average diameter of the carbon nanotubes contained in the conductive layer is in the range of 0.4 to 50 nm. The conductive tape for observation according to any one of claims 1 to 3, wherein the thickness of the polymer film is 12 μm or more and 75 μm or less. The conductive tape for observation according to any one of claims 1 to 3, wherein the observation is an electron microscope observation.

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