JP2019204713A - Conductive tape for observation - Google Patents

Abstract

To provide a conductive tape for observation that has little variation in observation.SOLUTION: The present invention provides a conductive tape for observation that is a conductive tape having a conductive layer laminated on at least one side of a polymer film, the conductive layer containing a three-dimensional crosslinked structure having carbon nanotubes and amide ester bonds, and the conductive layer surface having a water contact angle of less than 60°.SELECTED DRAWING: None

Description

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

  Conventionally, a microtome is widely known as an apparatus for producing thin slice samples used for physicochemical sample analysis and microscopic observation of biological samples, etc., and reduces the burden on workers for producing thin slice samples. At the same time, in order to reduce a decrease in accuracy of a thin slice sample, Patent Document 1 (Japanese Patent Laid-Open No. 2004-28910) and Patent Document 2 (Japanese Patent Laid-Open No. 2000-275538) describe a thinly sliced sample as a carrier tape. It has been proposed to keep it.

  This carrier tape needs to be able to continuously collect sections cut with a microtome without wrinkles, etc., and to be observed with an electron microscope as it is. However, such a carrier tape has not been provided yet.

JP 2004-28910 A JP 2000-275538 A

The subject of this invention is providing the electroconductive tape for observation with small dispersion | variation in observation.
Another object of the present invention is to provide an electroconductive tape for observation in which the collected section can be easily visually confirmed in addition to the above problems.

  According to the present invention, a conductive tape having a conductive layer laminated on at least one surface of a polymer film, the conductive layer containing a three-dimensional crosslinked structure having a carbon nanotube and an amide ester bond, An observation conductive tape having a water contact angle of less than 60 ° is provided.

In addition, according to the present invention, as a preferred embodiment of the present invention, a metal alkoxide layer is provided between the polymer film and the conductive layer, and a visible light region (400 nm or more and 800 nm or less as viewed from the conductive layer surface of the conductive tape). ) Having a first reflection bottom peak in a wavelength range of 475 nm or more and 650 nm or less, and a ratio between the maximum reflectance of the first reflection peak and the minimum reflectance in the reflection spectrum (maximum reflectance / minimum reflectance). Ratio) is 1.2 times or more, and the transmission color tones a * and b * in the CIE-Lab colorimetric method measured from the conductive layer surface of the conductive tape are the following formulas (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, the carbon nanotubes contained in the conductive layer 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 an electron microscope observation. An electroconductive tape for observation comprising the above is also provided.

  According to the present invention, since a conductive layer containing a carbon nanotube and a three-dimensional cross-linked structure having an amide ester bond is used, the conductive characteristics are stable, and even when bent, cracks and disconnections are unlikely to occur, and flatness is also achieved. This can be maintained, and when the thinly sliced sample is floated in a water bath and then squeezed 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 a sample that has been sliced continuously with no variation.

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

It is a figure which shows the reflection spectroscopy spectrum of Example 2 of this invention, and the appearance of the cutting piece on an electroconductive tape. It is a figure which shows the reflection spectroscopy spectrum of Example 3 of this invention, and the appearance of the cutting piece on an electroconductive tape. It is a figure which shows the reflection spectroscopy spectrum of Example 4 of this invention, and the appearance of the cutting piece on an electroconductive tape.

  In general, as the conductive layer, an inorganic conductive layer such as carbon or ITO by vacuum film formation, an organic conductive layer using a conductive polymer such as PEDOT-PSS, and a conductive material such as metal wire or carbon. There are various types such as a conductive layer containing a material in a coating film.

  However, the conductive layer formed of carbon in a vacuum has an unstable surface resistance value, and ITO has a problem that the ITO cracks when the slice is collected and the ITO crack is visible when observed with an electron microscope. There is a problem that the contrast of the electron microscope image is lowered by secondary electrons. In addition, the conductive polymer has a problem of being charged up when observed with an electron microscope, and the conductive layer formed of silver nanowires is mesh-like, so it easily affects the electron microscope image, and the conductive layer has flatness. It is easily damaged. In addition, in a conductive layer using carbon nanotubes as a conductive material, the carbon nanotubes are likely to drop off, and the surface resistance tends to become unstable.

  However, surprisingly, by using a conductive layer containing a carbon nanotube and a three-dimensional cross-linked structure having an amide ester bond, the conductive properties are stable, and even when bent, cracks and disconnection are unlikely to occur, and flatness It was also found that when the sample is continuously observed using a water bath, contamination of the water bath and 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) viewed from the conductive layer surface of the conductive tape. In the spectrum, it has also been found that the first reflective bottom peak is present in the wavelength range of 475 nm or more and 650 nm or less, whereby the visual visibility is further improved.

  Therefore, as described above, the conductive tape for observation of the present invention has a conductive layer containing a carbon nanotube and a three-dimensional crosslinked structure having an amide ester bond laminated on at least one surface 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 in the visible light region (400 nm or more and 800 nm or less) viewed from the conductive layer surface of the conductive tape. It is characterized by having a first reflective bottom peak in the range and will be described in detail below.

<Conductive layer>
The conductive layer in the present invention contains a three-dimensional crosslinked structure having at least a carbon nanotube and an amide ester bond.

The content of carbon nanotubes in the conductive layer can be adjusted as appropriate according to the 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 preferred content of the carbon nanotubes, preferably in the range of 1 to 30 mg / ^{m 2,} more preferably in the range of 2 to 20 mg / ^{m 2,} in particular in the range of 3~17mg / ^{m 2} is preferred.

Also, the total solid content coating amount of the conductive layer is suitably in the range of 2~90mg / ^{m 2,} preferably in the range of 3~60mg / ^{m 2,} the range of 4~50mg / ^{m 2} is preferred.

  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 solution containing a carbon nanotube dispersion 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. Of these, the slot die coating method is preferably used.

  The carbon nanotube to be contained in the conductive layer is not particularly limited as long as it has a shape obtained by winding one surface of graphite into a cylindrical shape, and is a single layer in which one surface of graphite is wound into one layer. Both carbon nanotubes and multi-walled carbon nanotubes wound in multiple layers can be applied.

  As the carbon nanotube, 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, the average diameter of the carbon nanotubes is preferably 1 to 10 nm and the average length is 1 to 10 μm. From the viewpoint of maintaining a higher level of flatness, it is preferable to use carbon nanotubes from which aggregates have been removed by centrifugation or the like.

  The carbon nanotube dispersion 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 an anionic dispersant, a cationic dispersant, and an amphoteric dispersant. Among these ionic dispersants, anionic dispersants are preferably used because of excellent dispersibility and dispersion retention of carbon nanotubes. Among anionic dispersants, carboxymethylcellulose and its salts such as sodium salt, ammonium salt, polystyrene sulfonic acid salt and the like 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 most preferable is carboxymethylcellulose or a salt thereof.

  Incidentally, as described above, the conductive layer in the present invention is characterized by containing a three-dimensional crosslinked structure having an amide ester bond. This three-dimensional crosslinked structure having an amide ester bond includes, for example, a carbon nanotube dispersion containing a cross-linking agent having an oxazoline group and a dispersant having a carboxyl group, and coating the carbon nanotube dispersion on a polymer substrate. When dried, the oxazoline group of the crosslinking agent and the carboxyl group of the dispersing agent react by the following chemical formula to form a three-dimensional crosslinked structure having an amide ester bond.

  Since the conductive layer contains a three-dimensional crosslinked structure having an amide ester bond, 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 cutting pieces are collected. It becomes. This effect is very important in observing a sample that has been sliced continuously with an electron microscope, etc. If this elution is large, for example, a conductive sample that has been sliced in a water bath and then immersed in the water bath. When an attempt is made to scoop up with a conductive tape, there will be variations in observation due to contamination of the water bath or deterioration of the conductive tape. When a three-dimensional crosslinked structure having an amide ester bond is formed by reacting a crosslinking agent and a dispersant, the amount of the crosslinking agent added is in the range of 1 to 100 parts by weight with respect to 100 parts by weight of the dispersant. Preferably, 10-50 weight part is further more preferable. If the addition amount 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 nanotube tends 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 within a range not impairing the effects of the present invention. As other specific cross-linking agents, cross-linking agents having an lysine ring or carboimide are generally known. However, the cross-linking agent having an aridine ring has problems of toxicity and handling, and the cross-linking agent having a carboimide has a high reactivity in an acidic atmosphere, and has a problem that the carbon nanotube dispersion liquid is easily thickened and gelled.

  In order to improve the dispersibility of the carbon nanotube, the conductive layer in the present invention preferably contains a dispersant as described above, and the content of the dispersant does not deteriorate the conductivity (surface resistance value) of the carbon nanotube. And from a viewpoint of ensuring favorable dispersibility, the range of 50-1000 mass parts is preferable with respect to 100 mass parts of carbon nanotubes, the range of 100-600 mass parts is more preferable, and the range of 200-400 mass parts is especially. preferable.

  The dispersion medium used for the preparation of the carbon nanotube dispersion liquid is preferably water from the viewpoints that the above-described dispersant can be safely dissolved and that the waste liquid can be easily treated.

  The carbon nanotube dispersion is, for example, a carbon nanotube and a dispersing agent mixed 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, a resolver. It can be prepared by dispersing using a paint shaker or the like. These mixing and dispersing machines may be used alone or may be dispersed stepwise by combining a plurality of mixing and dispersing machines.

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

  In applying the carbon nanotube dispersion liquid, alcohol or a surfactant can be contained in the carbon nanotube dispersion liquid in order to improve the coating property. Among these, alcohol is preferable, and 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, and specifically, the contact angle with water is preferably 70 degrees or less, and more preferably 55 degrees or less. It is known that when the contact angle of the conductive layer with water is large, the cut piece is wrinkled when the microtome cut piece is collected, making it difficult to observe the cut piece with an electron microscope.

  When the contact angle of the conductive layer with water is large, plasma treatment such as corona treatment or UV / ozone treatment can be performed 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 made of a metal alkoxide represented by the general formula of M (OR) n, where M is a metal element, R is an alkyl group, and n is an oxidation number of the metal element. I mean. Examples of M in the general formula include Si, Mg, Ge, Li, Na, Fe, Ga, Sb, Sn, and Ta. 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, γ-glycidoxypropyltrimethoxy Silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, vinyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyldimethoxysilane, Examples thereof include γ-aminopropyltriethoxysilane.

  These alkoxysilanes are preferably used in a mixture of two or more from the viewpoints of the mechanical strength, adhesion and solvent resistance of the layer, and in particular from the viewpoint of solvent resistance, It is preferable that the alkoxysilane which has an amino group in a molecule | numerator is contained in the range of 0.5-40% of a ratio. Particularly preferred is the combined use of γ-glycidoxypropyltrimethoxylane and methyltrimethoxysilane.

  Alkoxysilane may be used as a monomer or may be used after being hydrolyzed and dehydrated and condensed into a suitable oligomer. Usually, a coating solution dissolved and diluted in an appropriate organic solvent is applied onto a substrate. . The coating film formed on the substrate is hydrolyzed by moisture in the air and the like, and subsequently cross-linked by dehydration condensation.

  In general, an appropriate heat treatment is required to promote crosslinking, and it is preferable to perform a heat treatment for several minutes or more at a temperature of 100 ° C. or higher in the coating process. In some cases, the degree of crosslinking can be further increased by irradiating the coating film with actinic 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.

  For coating, a method using a known coating machine such as a doctor knife, bar coater, gravure roll coater, curtain coater, knife coater, spin coater, spray method, dipping method or the like is used.

  Since the metal alkoxide layer obtained in this way is easy to suppress wrinkles from entering the cut piece when the cut piece of the microtome is collected, it is preferable to make the surface more hydrophilic. As a method for hydrophilizing the metal alkoxide layer, a method of mixing a resin containing a hydroxyl group, a method of adding a resin having a quaternary ammonium salt, or a surfactant can be employed.

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

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

<Optical characteristics>
The electroconductive tape for observation of the present invention has a wavelength 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 in the visible light region (400 nm or more and 800 nm or less) viewed from the surface of the conductive layer. The first reflection peak is preferably in the range, particularly preferably in the range of 490 nm to 630 nm. By setting the first reflection peak in this region, the reflection color tone of the conductive tape becomes bluish, so that the microtome cutting pieces deposited on the conductive tape can be easily recognized visually. From such a viewpoint, it is preferable that the ratio (maximum reflectance / minimum reflectance) between the maximum reflectance of the first reflection peak and the minimum reflectance in the reflection spectrum is 1.2 times or more.

The transmission color tones a * and b * in the CIE-Lab colorimetric method measured from the surface on the low surface resistance layer side of the conductive tape in the present invention preferably satisfy the following formulas (1) and (2), respectively. .
−2.0 <a * <0.0 (1)
2.0 <b * <4.0 (2)
Further preferred a * and b * are
−1.0 <a * <0.0 (1 ′)
2.5 <b * <4.0 (2 ′)
Range.

  The surface resistance value of the conductive layer surface of the conductive tape in the present invention is preferably 100 Ω / □ or more and 5,000 Ω / □ or less because it is easy to suppress wrinkles from entering the cut piece when the microtome cut piece is collected. More preferably, it is 200Ω / □ or more and 3,000Ω / □ or less, particularly 500Ω / □ or more and 1500Ω / □ or less.

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

<Polymer film>
The polymer film in the present invention may be any known per se and is not particularly limited. Examples of the resin forming the polymer film include polyolefin resins such as polyester resin, polypropylene resin and polyethylene film, polylactic acid resin, polycarbonate resin, acrylic resin such as polymethacrylate resin and polystyrene resin, polyamide resin such as nylon resin, A polyvinyl chloride resin, a polyurethane resin, a fluororesin, a polyphenylene resin, etc. are mentioned, These may be a homopolymer or a copolymer, or may be a mixture of a plurality of resins.

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

  Of these, polyester films and polycarbonate films are preferable in terms of mechanical properties, dimensional stability, transparency, and polyethylene terephthalate films and polyethylene naphthalene dicarboxylate films in terms of mechanical strength and versatility. And a polyethylene-2,6-naphthalenedicarboxylate film is particularly preferable.

  The thickness of the polymer film is not particularly limited as long as it can ensure flexibility when formed into a tape and has excellent handling properties, but is preferably 12 μm or more, and preferably 75 μm or less. The minimum of the thickness of a preferable polymer film is 20 micrometers, and also 30 micrometers. Furthermore, the upper limit of the thickness of a preferable polymer film is 70 μm, and further 60 μm. The polymer film may be a composite film obtained by coextrusion, or a film obtained by bonding the obtained film by various methods. Moreover, in order to improve adhesiveness with the above-mentioned low surface-resistance layer, you may form the easily bonding layer in the surface separately.

[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. Various measured values in the present invention are measured by the following methods, and unless otherwise specified, parts and% mean parts by weight and% by weight, respectively.
(1) Measurement of surface resistance (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 55% relative humidity.
(2) Measurement of thickness of each layer
The cross section of the conductive tape was measured by observation with a transmission electron microscope (TEM). Observation was performed by selecting a magnification at which the thickness of each layer was 50% or more in the vertical direction within one field of view.
(3) Contact angle of water The contact angle of water 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 spectrum spectrum The reflection spectrum 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 using SE-6000 manufactured by Nippon Denshoku Co., Ltd. with the conductive layer surface side of the conductive tape placed on the light receiving side.
(6) Average diameter and average length of carbon nanotube The average diameter and average length of the carbon nanotube 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-glycidoxypropyltrimethoxylane (“KBM403” manufactured by Shin-Etsu Chemical Co., Ltd.) and methyltrimethoxysilane (“KBM13” manufactured by Shin-Etsu Chemical Co., Ltd.) Were mixed at a molar ratio of 1: 1, and the alkoxysilane was hydrolyzed with an acetic acid aqueous 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.) is added at a ratio of 1 part by weight of solid content to 20 parts by weight of solid content of alkoxysilane hydrolyzate 1. Further, a metal alkoxide solution is diluted with a mixed solution of isopropyl alcohol and n-butanol (weight ratio of isopropyl alcohol and n-butanol is 2: 1) so that the solid concentration is 3 parts by weight with respect to 100 parts by weight of the solution. -Created A.
A metal alkoxide solution-B was prepared by adding 1 part by weight of carbodilite SV-02 (Nisshinbo Chemical Co., Ltd.) having a carbodiimide group to the metal alkoxide solution-A with respect to 100 parts by weight of the metal alkoxide solution.

(8) Carbon nanotube dispersion liquid For the carbon nanotube dispersion liquid, a commercially available carbon nanotube dispersion liquid using carboxymethyl cellulose as a dispersant is prepared, and this is centrifuged to form an aggregate having a particle diameter of 5 μm or more. The carbon nanotube dispersion liquid-I was removed as much as possible. 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. One part by weight of a cross-linking agent Evocross WS-700 (manufactured by Nippon Shokubai Co., Ltd.) having an oxazoline group with respect to 100 parts by weight of the dispersion was added to the carbon nanotube dispersion after centrifugation. This was designated as carbon nanotube dispersion liquid-II.

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

(10) Evaluation of conductive tape as carrier film The conductive tape is immersed in distilled water for 10 minutes, and the presence or absence of appearance change is confirmed. Further, distilled water is included in the cotton swab, and the conductive layer surface side is lightly rubbed 10 times with a cotton swab to confirm the presence or absence of peeling of the conductive layer.
Said evaluation was performed and it determined by the following references | standards.
Good: No color unevenness due to peeling of the conductive layer, and the cotton swab has no coloring due to the conductive layer. Unusable: There is color unevenness due to peeling of the conductive layer, or the cotton swab has coloring due to the conductive layer.

[Example 1]
As a polymer film, prepare a polyester film (trade name: Q65HW, substrate thickness: 50 μm) manufactured by Teijin Film Solutions, apply the above-mentioned carbon nanotube dispersion liquid-II, and dry at 140 ° C. for 5 minutes to form a conductive layer. Formed. The surface resistance value after forming the carbon nanotube layer was 1200Ω / □.
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 containing distilled water, but no peeling of the conductive layer was observed.

[Example 2]
A polyester film (trade name: Q65HW, base material thickness 50 μm) prepared by Teijin Film Solutions Co., Ltd. is prepared as a polymer film, and the above-mentioned metal alkoxide solution-A is applied to one surface thereof at 130 ° C. for 2 minutes. The metal alkoxide layer-1 was formed by drying. On the metal alkoxide layer-1, the above-mentioned carbon nanotube dispersion liquid-II was applied and dried at 140 ° C. for 5 minutes to form a conductive layer. The surface resistance value after forming the carbon nanotube layer was 1050Ω / □. Further, 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 containing distilled water, but no peeling of the conductive layer was observed.

[Example 3]
A conductive tape was prepared in the same manner as in Example 1 except that the metal alkoxide layer in Example 1 was replaced with the metal alkoxide solution-B.
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 containing distilled water, but no peeling of the conductive layer was observed.

[Comparative Example 1]
A conductive tape was prepared in the same manner 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.
When the conductive layer was lightly rubbed with a cotton swab containing distilled water, the conductive layer was easily peeled off.

[Comparative Example 2]
A conductive tape was prepared in the same manner as in Example-2 except that the carbon nanotube dispersion was replaced with the carbon nanotube dispersion-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.

[Example 4]
Except having changed the film thickness of the metal alkoxide layer, the same operation as Example 2 was performed and the electroconductive tape was created.
The reflection spectrum after forming the metal alkoxide layer on the polymer film is shown in FIG. 3, and 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 containing distilled water, but no peeling of the conductive layer was observed.
Table 1 shows the characteristics of the obtained conductive tape.

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

Claims (10)

  A conductive tape having a conductive layer laminated on at least one surface of a polymer film, the conductive layer containing a three-dimensional cross-linked structure having a carbon nanotube and an amide ester bond, and a water contact angle on the surface of the conductive layer being 60 ° An electroconductive tape for observation characterized by being less than.   The electroconductive tape for observation of Claim 1 which has a metal alkoxide layer between a polymer film and a conductive layer.   The conductive for observation according to claim 2, wherein in a reflection spectrum in a visible light region (400 nm or more and 800 nm or less) viewed from the conductive layer surface of the conductive tape, the first reflection bottom peak is in a wavelength range of 475 nm or more and 650 nm or less. tape.   The conductive tape for observation according to claim 3, wherein a ratio (maximum reflectance / minimum reflectance) between the minimum reflectance of the first reflection bottom peak and the first reflection peak in the reflection spectrum is 1.2 times or more. The conductive tape for observation according to claim 3, wherein the transmission color tones a * and b * in the CIE-Lab colorimetric method measured from the conductive layer surface of the conductive tape satisfy the following expressions (1) and (2), respectively.
−2.0 <a * <0.0 (1)
2.0 <b * <4.0 (2)   The conductive tape for observation according to claim 1, wherein the conductive tape has a surface resistance value of 100 Ω / □ or more and 5,000 Ω / □ or less.   3. The observation conductive tape according to claim 2, wherein the metal alkoxide is alkoxysilane.   The observation conductive tape according to claim 1, wherein an average diameter of the carbon nanotubes contained in the conductive layer is in a range of 0.4 to 50 nm.   The conductive tape for observation according to claim 1, wherein the polymer film has a thickness of 12 μm to 75 μm.   4. The observation conductive tape according to claim 1, wherein the observation is an electron microscope observation.