JP7324492B2 - Method for producing composition containing carbon nanotube and method for producing composite material - Google Patents

Description

The present invention relates to a method for producing a carbon nanotube-containing composition and a method for producing a composite material.

Carbon nanotubes are materials that are extremely lightweight and have excellent electrical properties, thermal conductivity, and mechanical properties. Therefore, carbon nanotubes are attracting attention as industrial materials for compounding with other materials.

In particular, a carbonna tube having a small average diameter has a large specific surface area, and even a small amount of carbon nanotubes can provide excellent reinforcing effects. However, such carbon nanotubes tend to agglomerate due to van der Waals forces, and exist in the composite material in the form of thick bundles (bundles), for example, as agglomerates. If such a thick bundle or agglomerate exists, not only can the large specific surface area of the carbon nanotube not be utilized, but the composite material tends to become a starting point of fracture.

After mixing and stirring a CNT dispersion liquid in which single-walled carbon nanotubes with a small average diameter are dispersed in a large amount of organic solvent and a matrix solution in which fluororubber is dissolved in an organic solvent, the organic solvent is removed by drying to obtain 1 wt. % CNT rubber has been proposed (Patent Documents 1 to 3).

JP 2014-196246 A JP 2016-175836 A JP 2018-39722 A

However, the methods of Patent Literatures 1 to 3 require removal of a large amount of organic solvent during compounding, making it difficult to be industrially put into practical use. In addition, since it is mixed with the CNT dispersion, the matrix material is limited to those that dissolve in an organic solvent.

Accordingly, the present invention provides a method for producing a carbon nanotube-containing composition and a method for producing a composite material, which can combine carbon nanotubes with a polymeric substance without using a large amount of organic solvent.

[1] One aspect of the method for producing a carbon nanotube-containing composition according to the present invention is
A mixture containing carbon nanotubes having an average diameter of 0.4 nm to 15.0 nm and a polyhydric alcohol is pressurized and compressed, and then the pressure is released or reduced to restore the original volume to obtain a carbon nanotube-containing composition. including a mixing step to obtain
The amount of the polyhydric alcohol compounded is 1.0 parts by mass or more and less than 10.0 parts by mass with respect to 1.0 parts by mass of the carbon nanotubes.

[2] In one aspect of the method for producing the carbon nanotube-containing composition,
The polyhydric alcohol can include at least one of a dihydric alcohol and a trihydric alcohol.

[3] One aspect of the method for producing a composite material according to the present invention is a method for producing a composite material using the carbon nanotube-containing composition obtained by one aspect of the method for producing the carbon nanotube-containing composition. ,
The mixing step is a first mixing step,
further comprising a second mixing step of mixing the carbon nanotube-containing composition obtained in the first mixing step with a polymeric substance to obtain a composite material;
A content of the carbon nanotubes in the composite material is 5.0 parts by mass or more and 40.0 parts by mass or less with respect to 100 parts by mass of the polymer substance.

[4] One aspect of the method for producing a composite material according to the present invention is a method for producing a composite material using the carbon nanotube-containing composition obtained by one aspect of the method for producing the carbon nanotube-containing composition. ,
The mixing step is a first mixing step,
a second mixing step of mixing the carbon nanotube-containing composition obtained in the first mixing step with a first polymeric substance to obtain a precursor;
a third mixing step of further mixing the precursor with the second polymeric substance to obtain the composite material;
characterized by further comprising

[5] In one aspect of the method for manufacturing the composite material,
The first polymeric substance and the second polymeric substance are thermoplastic resins,
The content of the polyhydric alcohol in the precursor is less than 400.0 parts by mass with respect to 100 parts by mass of the thermoplastic resin,
A content of the carbon nanotubes in the composite material may be 0.1 parts by mass or more and 15.0 parts by mass or less with respect to 100 parts by mass of the thermoplastic resin.

[6] In one aspect of the method for manufacturing the composite material,
The first polymeric substance and the second polymeric substance are rubber components,
The content of the polyhydric alcohol in the precursor is 200.0 parts by mass or less with respect to 100 parts by mass of the rubber component,
A content of the carbon nanotubes in the composite material may be 0.1 parts by mass or more and 30.0 parts by mass or less with respect to 100 parts by mass of the rubber component.

FIG. 1 is a diagram schematically showing the first mixing step. FIG. 2 is a diagram schematically showing the second mixing step. FIG. 3 is a diagram schematically showing the third mixing step. 4 is a graph showing the DMA measurement results (temperature dependence of storage elastic modulus E') of the sample of Example 1. FIG. 5 is an optical micrograph of the composite material of Example 2. FIG. 6 is an optical micrograph of the composite material of Example 11. FIG. 7 is an optical micrograph of the composite material of Comparative Example 2. FIG. 8 is an optical micrograph of the composite material of Comparative Example 6. FIG. 9 is an optical micrograph of the composite material of Comparative Example 20. FIG. 10 is an electron micrograph of the composite material of Example 5. FIG. 11 is an electron micrograph of the composite material of Comparative Example 4. FIG. 12 is an electron micrograph of the composite material of Comparative Example 8. FIG. 13 is an electron micrograph of the composite material of Example 21. FIG. 14 is an electron micrograph of the composite material of Comparative Example 31. FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

1. Method for producing carbon nanotube-containing composition In the method for producing a carbon nanotube-containing composition according to the present embodiment, a mixture containing carbon nanotubes having an average diameter of 0.4 nm to 15.0 nm and a polyhydric alcohol is compressed under pressure. After that, the pressure is released or reduced to restore the original volume to obtain the carbon nanotube-containing composition.

In the following description, the mixing step in the method for producing a carbon nanotube-containing composition will be referred to as the "first mixing step" in order to clearly distinguish it from the second mixing step, etc., which will be described later.

1.1. First Mixing Step The first mixing step is a step of pressurizing and compressing a mixture containing carbon nanotubes and a polyhydric alcohol, and then releasing or reducing the pressure to restore the original volume. It can be inferred that when the volume of the mixture is changed in the first mixing step, the mixture flows so as to undergo pseudo-elastic deformation, allowing the polyhydric alcohol to permeate between the aggregated carbon nanotubes. The first mixing step is preferably performed at a relatively low temperature at which the polyhydric alcohol does not evaporate.

A mixture including carbon nanotubes and a polyhydric alcohol can be prepared prior to the first mixing step. For example, the mixture is prepared by putting predetermined amounts of carbon nanotubes and polyhydric alcohol in a container and stirring them. A polyhydric alcohol alone has low elasticity and viscosity, but a mixture containing carbon nanotubes has high elasticity and viscosity.

A specific example of the first mixing step will be described with reference to FIG.

A mixture 80 is put into the open roll 2 shown in FIG. 1 and the mixture 80 is wound around the first roll 10 . A roll gap d between the first roll 10 and the second roll 20 can be set to, for example, more than 0.0 mm and 0.5 mm or less. The surface temperatures of the first roll 10 and the second roll 20 are set to a temperature at which dew condensation on the rolls is difficult to occur and the polyhydric alcohol is difficult to evaporate. It can be above 30°C and below. The kneading time in the first mixing step can be, for example, 5 minutes or more and 20 minutes or less. By performing the first mixing step, the polyhydric alcohol can be sufficiently permeated between the aggregated carbon nanotubes, and a situation can be created in which the carbon nanotubes are easily fibrillated in the second mixing step. Since the mixture is highly elastic and viscous, after the mixture is compressed between the rolls, an elastic restoring force is generated when the pressure is released. It can be inferred that the carbon nanotubes move together with the movement of the polyhydric alcohol due to this restoring force, and the polyhydric alcohol enters the gaps between the carbon nanotubes forming the bundle.

Although an example of using the open roll 2 as the first mixing step has been described, other mixing methods can be adopted as long as the mixture can be restored after being compressed in volume. For example, a dispersing device (homogenizer) that pressurizes and compresses the liquid while fluidizing it, generates cavitation and turbulence, and then rapidly decompresses the liquid may be used.

1.2. Carbon Nanotubes Carbon nanotubes used in the first mixing step have an average diameter of 0.4 nm to 15.0 nm. Additionally, the carbon nanotubes can have an average diameter of 1.0 nm to 15.0 nm. Single-walled carbon nanotubes having an average diameter of 1.0 nm to 5.0 nm, which are particularly difficult to defibrate, may be used. The average diameter of carbon nanotubes can be measured by observation with an electron microscope. The carbon nanotube may be subjected to a known surface treatment in order to improve reactivity with a polymeric substance, which will be described later. In the detailed description of the present invention, the average diameter of the carbon nanotube is obtained by measuring the diameter of 200 or more points from an electron microscope, for example, at a magnification of 50,000 times (magnification can be changed as appropriate depending on the size of the carbon nanotube). It can be obtained by calculating as an average value.

Carbon nanotubes include single-wall carbon nanotubes (SWNT: single-wall carbon nanotubes), multi-wall carbon nanotubes (MWNT: multi-wall carbon nanotubes). Multi-walled carbon nanotubes include double-walled carbon nanotubes (DWNT). A carbon material partially having a carbon nanotube structure can also be used. In addition to the name of carbon nanotube, it is sometimes referred to by names such as graphite fibril nanotube and vapor-grown carbon fiber.

Carbon nanotubes can be obtained by a known production method, and commercially available carbon nanotubes may also be used. For example, carbon nanotubes can be obtained by vapor deposition. The vapor deposition method is also called a catalytic vapor deposition method (Catalytic Chemical Vapor Deposition: CCVD), and produces untreated carbon nanotubes by vapor phase pyrolysis of a gas such as a hydrocarbon in the presence of a metal catalyst. The method. To explain the vapor phase growth method in more detail, for example, organic compounds such as benzene and toluene are used as raw materials, and organic transition metal compounds such as ferrocene and nickelcene are used as metal catalysts. It is introduced into a reactor set at a reaction temperature of ~ 1000 ° C, and the floating reaction method that generates carbon nanotubes in a floating state or on the wall of the reactor, or supported on ceramics such as alumina and magnesium oxide in advance. A catalyst supporting reaction method (Substrate Reaction Method) or the like can be used in which the metal-containing particles are brought into contact with a carbon-containing compound at a high temperature to generate carbon nanotubes on a substrate.

1.3. Polyhydric Alcohol The polyhydric alcohol in the carbon nanotube-containing composition makes it easier to defibrate the carbon nanotubes when the carbon nanotube-containing composition is composited with a polymer substance. Specifically, the polyhydric alcohol permeates between aggregated carbon nanotubes in the first mixing step, so that bundles and agglomerates of carbon nanotubes can be easily loosened in the second mixing step described later.

Polyhydric alcohols can include at least one of dihydric alcohols and trihydric alcohols. Examples of dihydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol and neopentyl glycol. Examples of trihydric alcohols include glycerin, trimethylolethane, trimethylolpropane, cyclohexanedimethanol and the like. Polyhydric alcohols other than dihydric and trihydric alcohols may include, for example, pentaerythritol, diglycerin, polyglycerin, and the like.

The blending amount of the polyhydric alcohol is 1.0 parts by mass or more and less than 10.0 parts by mass with respect to 1.0 parts by mass of the carbon nanotubes. If the polyhydric alcohol is less than 1.0 part by mass, the effect of fibrillating the carbon nanotubes in the second mixing step is reduced. Moreover, when 10.0 parts by mass or more of the polyhydric alcohol is added, the processability in the second mixing step tends to deteriorate. Furthermore, the amount of the polyhydric alcohol to be blended can be preferably 1 part by mass or more and 8.0 parts by mass or less with respect to 1.0 part by mass of the carbon nanotube.

1.4. Carbon Nanotube-Containing Composition The carbon nanotube-containing composition obtained in the first mixing step is a paste-like substance containing carbon nanotubes and polyhydric alcohol. The mass ratio of carbon nanotubes and polyhydric alcohol in the carbon nanotube-containing composition is 1.0:1.0 to 1.0:10.0. The carbon nanotube-containing composition can be mixed with a matrix material such as a polymer substance or a metal and used as a raw material for compositing the carbon nanotube with the matrix material.

2. Method for Producing Composite Material The method for producing a composite material according to the present embodiment includes a second mixing step of mixing the carbon nanotube-containing composition obtained in the first mixing step with a polymeric substance to obtain a composite material. The method for producing the composite material comprises: a second mixing step of mixing the carbon nanotube-containing composition obtained in the first mixing step with a first polymer substance to obtain a precursor; and a third mixing step of mixing with the substance to obtain a composite material.

2.1. 2nd mixing process In the 2nd mixing process, a high shear force is applied to the polymer material, and the elastic restoring force of the polymer material is used to defibrate the carbon nanotubes and disperse them in the polymer material to produce a composite material. can do. Since the carbon nanotube-containing composition described above is used, carbon nanotubes can be composited with a polymer substance without using a large amount of organic solvent as in the conventional method.

The content of carbon nanotubes in the composite material is 5.0 parts by mass or more and 40.0 parts by mass or less with respect to 100 parts by mass of the polymer substance. If the content of the carbon nanotubes is 5.0 parts by mass or more, the carbon nanotubes constrain the polymer substance, so that the elastic restoring force can be used for mixing. Moreover, if the content of the carbon nanotubes is 40.0 parts by mass or less, the second mixing step can be carried out. Also, the content of carbon nanotubes in the composite material may be 5.0 parts by mass or more and 30.0 parts by mass or less with respect to 100 parts by mass of the polymer substance. In that case, the second mixing step can be carried out more easily.

At least one or more of thermoplastic resins, thermosetting resins, and rubber components can be selected as the polymer substance. The conditions for the mixing step differ depending on the polymeric substance that serves as the matrix.

The composite material obtained in the second mixing step may be used as a precursor (masterbatch) in the third mixing step described below.

2.1.1. Second Mixing Step Using Thermoplastic Resin The second mixing step when the polymeric substance is a thermoplastic resin will be described in detail.

In the second mixing step, the thermoplastic resin and the carbon nanotube-containing composition are mixed so that the carbon nanotubes are 5.0 parts by mass or more and 40.0 parts by mass or less with respect to 100 parts by mass of the thermoplastic resin. In the second mixing step, the carbon nanotubes can be 10.0 parts by mass or more and 30.0 parts by mass or less with respect to 100 parts by mass of the thermoplastic resin. It can be 15.0 parts by mass or more and 20.0 parts by mass or less.

In the second mixing step, the temperature at which the processing region appears in the storage modulus of the composite material near the melting point (Tm ° C.) of the thermoplastic resin is 1.06 times (T3 ° C. A low-temperature kneading step of kneading at a kneading temperature in the range up to the temperature of x1.06) can be included. In the case of a thermoplastic resin that does not have a melting point, the kneading temperature can be set from the storage elastic modulus using the glass transition point instead of the melting point.

In the low-temperature kneading step, an apparatus for melting and molding a thermoplastic resin, such as an open roll, closed kneader, extruder, injection molding machine, or the like, can be used. A method using an open roll 2 as shown in FIG. 2 will be described.

In the low-temperature kneading step, the roll gap d between the first roll 10 and the second roll 20 is set to, for example, 0.5 mm or less, more preferably more than 0.0 mm and 0.5 mm or less, and the polymer substance (here Then, the “thermoplastic resin”) 30 and the carbon nanotube-containing composition 80 can be put into the open roll 2 and kneaded.

When the surface speed of the first roll 10 is V1 and the surface speed of the second roll 20 is V2, the surface speed ratio (V1/V2) between the two in this step can be 1.05 to 3.00, Further, it can be from 1.05 to 1.2. By using such a surface velocity ratio, the desired high shear force can be obtained. The mixture extruded from such a narrow roll gap has moderate elasticity at the kneading temperature and has a moderate viscosity in the temperature range, so the restoring force due to the elasticity of the thermoplastic resin is large. The carbon nanotubes can move greatly along with the deformation of the thermoplastic resin at that time. The rubber elastic region will be described later.

The kneading temperature is the surface temperature of the mixture in the low temperature kneading step, not the set temperature of the processing equipment. It is desirable to measure the actual surface temperature of the resin as much as possible for the kneading temperature, but if it cannot be measured, measure the surface temperature of the resin immediately after taking out the composite material from the processing equipment, and use that temperature as the kneading temperature during processing. be able to.

In the case of the open roll 2, as shown in FIG. 1, the surface temperature of the polymeric material 30 wound around the first roll 10 can be measured using a non-contact thermometer 40. FIG. The non-contact thermometer 40 may be placed at a position other than immediately after passing through the nip, preferably above the first roll 10 . Immediately after passing through the nip, the temperature of the polymeric substance changes rapidly and is unstable, so it is desirable to avoid it.

If the surface temperature of the composite material cannot be measured during the low-temperature kneading process, such as when using an internal kneader or extruder, the surface temperature of the composite material should be measured immediately after it is removed from the apparatus after kneading. , it can be confirmed that it is within the kneading temperature range. Further, when using a kneader capable of accurately monitoring the temperature of the resin during mixing, it may be confirmed that the monitored temperature is within the predetermined kneading temperature range.

According to the method for producing a composite material, the carbon nanotubes, which tend to aggregate easily, can be separated from each other and dispersed in the thermoplastic resin, and the dispersed state can be maintained in the thermoplastic resin.

The low-temperature kneading step is a flat region from a temperature near the melting point (a flat region where the storage elastic modulus (E') hardly decreases even after the melting point in the results of a dynamic viscoelasticity test (hereinafter referred to as a DMA test), That is, by using up to a part of the rubber elastic region like an elastomer), aggregated carbon nanotubes are defibrated so as to be loosened and dispersed in a thermoplastic resin. In order to set the kneading temperature range, it is necessary to perform a DMA test in advance on a composite material sample of that formulation. The low-temperature kneading temperature is described in detail in JP-A-2017-145406.

First, a DMA test was performed on a composite material sample of a predetermined composition, the horizontal axis was temperature, the left vertical axis was the logarithm value (log(E')) of the storage modulus (E'), and the right vertical axis was storage A graph is created as the differential value (d(log(E'))/dT) of the logarithm of the elastic modulus (E') (log(E')) with respect to temperature (eg, FIG. 4).

The log(E') graph has an inflection point P1 near the melting point of the thermoplastic resin. The inflection point P1 clearly appears as an extreme point in the graph of d(log(E'))/dT. The inflection point appears at slightly different temperatures by changing the blending amount of CNTs and the like.

Next, from the graph of d (log (E ')) / dT, the temperature range of the first region W1 in which the slope in the region below the melting point before the flow starts is constant is obtained, and log (E '
) and the tangent line L1 of the graph of log(E′) at the inflection point P1, the temperature at the intersection point P2 is obtained as the processing region manifestation temperature T2. The processing region manifestation temperature T2 is the lower limit temperature at which kneading processing in the low-temperature kneading step is possible.

Further, from the graph of d(log(E′))/dT, the range where the slope of the graph of log(E′) is constant is defined as a second region W2, and log(E′) in the temperature range of the second region W2 and the tangent line L1 of the graph of log(E') at the inflection point P1 is determined as the flat region appearance temperature T3.

It should be noted that the regions (W1, W2) where the slope is constant are assumed to exist in a temperature range of at least 10° C. or more where the slope of the log(E′) graph is constant. The flat area is the second area W2.

A temperature higher than the temperature T1 of the inflection point P1 thus obtained, and a temperature at which the viscosity of the composite material sample becomes low and does not flow out, for example, 1.06 times the flat region manifestation temperature T3 (T3 ° C. × 1.06) is defined as the upper limit of the kneading temperature. It is believed that any thermoplastic resin can be used to defibrate carbon nanotube bundles and agglomerates up to a temperature T4 that is 1.06 times (T3°C x 1.06) the temperature at which the flat region appears (T3°C). be done. Within the temperature range from the working zone manifestation temperature T2 to the temperature T4 that is 1.06 times (T3°C x 1.06) the flat zone manifestation temperature (T3°C), the mixture has moderate elasticity and moderate viscosity. Therefore, processing is possible and the carbon nanotubes can be defibrated.

The lower limit of the kneading temperature in the low-temperature kneading step may be equal to or higher than the inflection point temperature T1 at the inflection point P1. This is because the processing of the second mixture becomes easier. It should be noted that the temperature T2 and the temperature T4 are slightly different by changing the blending amount of the carbon nanotubes.

The kneading temperature is a relatively low temperature that has not been used as a processing temperature for thermoplastic resins, and in particular, it falls within a low temperature range that has not been used as a processing temperature for mixtures.

In the present invention, "melting point (Tm)" refers to a value measured using differential scanning calorimetry (DSC) according to JIS K7121.

Since the carbon nanotubes tend to reaggregate when all the polyhydric alcohol volatilizes, the low-temperature kneading step is preferably carried out in a state in which the polyhydric alcohol is contained until the carbon nanotubes are completely defibrated and dispersed. Therefore, the range of the kneading temperature in the low-temperature kneading step is preferably below the boiling point of the polyhydric alcohol.

Thermoplastic resins used in the second mixing step include, for example, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polystyrene, polyethylene, polypropylene, polyacrylic acid, polymethacrylic acid, polymethylmethacrylate (PMMA), polyamide, and polyethylene. Terephthalate, polylactic acid, polyurethane, polyvinyl alcohol (PVA), polycarbonate (PC), polyacetal (POM), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), Polyimide (PI), fluorine resin (PFA) and the like can be used alone or in combination of two or more. When two or more resins are used in combination, a mixture of these different resins, a melt blend of different resins, or a copolymer can be used. As the thermoplastic resin, for example, polyethylene, polypropylene, or the like can be selected. Examples of copolymers of thermoplastic resins may include resins commonly called thermoplastic elastomers. Thermoplastic elastomers can be roughly divided into styrene (TPS: SBS (styrene-butylene-styrene block copolymer), SEBS (styrene-ethylene-butylene-styrene), olefin-based (TPO), vinyl chloride (TPVC), and urethane-based (TPU). , ester-based (TPEE), amide-based (TPAE), and the like can be used alone or in combination of two or more.

The thermoplastic resin may be a recycled plastic that is recycled from discarded plastic after being used. For example, a thermoplastic resin obtained by sorting, washing, pulverizing, and pelletizing waste plastics such as food containers, beverage containers, and trays may be used. The polyolefin resin component of the recycled plastic may be 80% by mass or more, and may be 90% by mass or more. Further, the main resin may be 50% by mass or more, more preferably 70% by mass or more, and particularly 80% by mass or more.

The thermoplastic resin may contain known additives such as antioxidants, plasticizers, flame retardants, etc., as long as they do not impair the effects of the present invention.

2.1.2. Second Mixing Step Using Rubber Component The second mixing step when the polymeric substance is a rubber component will be described in detail.

In the second mixing step, the rubber component and the carbon nanotube-containing composition are mixed such that the carbon nanotubes are 5.0 parts by mass or more and 40.0 parts by mass or less per 100 parts by mass of the rubber component. In the second mixing step, carbon nanotubes can be 5.0 parts by mass or more and 35.0 parts by mass or less with respect to 100 parts by mass of the rubber component, and further, 10.0 parts by mass or more and 30.0 parts by mass or less. can be.

Prior to the second mixing step, first, as shown in FIG. to generate free radicals. The free radicals of the rubber component generated by mastication are in a state where they are likely to bond with the carbon nanotubes.

Next, the carbon nanotube-containing composition 80 is added to the bank 34 of the polymer substance (rubber component) 30 wound around the first roll 10 and kneaded. At this stage, known additives used in rubber components may be mixed with the rubber component.

Furthermore, in the second mixing step, the roll gap d is set to, for example, 0.5 mm or less, more preferably more than 0.0 mm to 0.5 mm or less, and the polymer substance 30 mixed with the carbon nanotube-containing composition is thinly let through. The thin threading can be performed, for example, about 1 to 10 times.

The surface speed ratio (V1/V2) of the rolls in thin threading can be from 1.05 to 3.00, preferably from 1.05 to 1.2. A desired shear force can be obtained by using such a surface velocity ratio.

In this second mixing step, the roll temperature is set to a relatively low temperature, for example 0° C. to 50° C., more preferably 5° C. to 40° C., in order to obtain a shear force as high as possible. The measured temperature of the polymeric material (rubber component) 30 can also be adjusted from 0°C to 50°C.

The composite material extruded from the narrow gap between the open rolls 2 is greatly deformed by the restoring force due to the elasticity of the rubber component, and at that time the carbon nanotubes move greatly together with the rubber component.

Due to the shearing force thus obtained, a high shearing force acts on the rubber component, and the aggregated carbon nanotubes are separated from each other and fibrillated so that they are pulled out by the rubber molecules, and dispersed in the rubber component. be. In particular, since the rubber component has elasticity, viscosity, and chemical interaction with carbon nanotubes, the carbon nanotubes can be easily dispersed. Then, it is possible to obtain a composite material excellent in the dispersibility and dispersion stability of the carbon nanotubes (the carbon nanotubes are difficult to re-aggregate).

More specifically, when the rubber component and the carbon nanotubes are mixed in an open roll, the viscous rubber component penetrates into the carbon nanotubes, and a specific portion of the rubber component chemically interacts with the carbon nanotubes. Binds to highly active moieties. If the activity of the surface of the carbon nanotube is moderately high, it can be particularly easy to bond with rubber component molecules. Next, when a strong shearing force acts on the rubber component, the carbon nanotubes move along with the movement of the rubber component molecules, and the aggregated carbon nanotubes are separated by the restoring force of the rubber component due to the elasticity after shearing. , will be dispersed in the rubber component.

Thin threading is not limited to the open roll method, but may be an internal kneading method or a multi-screw extrusion kneading method, as long as the carbon nanotubes can be fibrillated in the rubber component by a shearing force. In short, in this step, it suffices if a shearing force capable of separating and fibrillating the aggregated carbon nanotubes can be applied to the rubber component. In particular, the open roll method is preferred because it allows not only control of the roll temperature, but also the actual temperature of the mixture to be measured and controlled. In cases other than the open roll method, it is preferable to keep the temperature of the mixture during kneading within the temperature range of the rolls in order to obtain an appropriate shearing force.

The composite material obtained by thinning is rolled by rolls to form a sheet having a predetermined thickness.

Examples of rubber components used in the second mixing step include natural rubber (NR), nitrile rubber (NBR), hydrogenated nitrile rubber (H-NBR), epoxidized natural rubber (ENR), and styrene-butadiene rubber (SBR). , chloroprene rubber (CR), ethylene propylene rubber (EPM), ethylene-propylene-diene copolymer (EPDM), butyl rubber (IIR), chlorobutyl rubber (CIIR), silicone rubber (Q), fluororubber (FKM, FFKM, FEPM, etc.), butadiene rubber (BR), epoxidized butadiene rubber (EBR), urethane rubber (U), polysulfide rubber (T), and the like can be employed.

2.1.3. Second Mixing Step Using Thermosetting Resin The second mixing step when the polymer substance is a thermosetting resin will be described in detail.

In the second mixing step, the carbon nanotube-containing composition is mixed with a thermosetting resin main agent, and kneaded at a kneading temperature in the range of 20° C. lower than the softening point of the main agent to 10° C. higher than the softening point. Furthermore, the process of mixing a hardening|curing agent can be included. If the temperature is near the softening point of the base compound, it is not completely liquid, and according to the test results, it is suitable for kneading temperatures ranging from 20°C lower than the softening point to 10°C higher than the softening point. It can be elastic and viscous.

As the thermosetting resin, a two-liquid mixed type resin using a main agent such as an epoxy resin, a phenol resin, or a urethane resin and a curing agent can be used, but the thermosetting resin is not limited thereto.

For the kneading step, for example, an open roll, closed kneader, extruder, or the like can be used.

The basic procedure is the same as for thermoplastic resins, but here, for epoxy resins, bisphenol A type base resin (solid at room temperature and softening point 64° C.) will be described as an example. First, mastication is performed at a temperature of 60 to 70° C. for the first roll 10 in FIG. 2 and a temperature of 50 to 60° C. for the second roll 20 . Next, the carbon nanotube-containing composition is gradually added to the main agent and mixed. After that, a thin threading step can be performed by setting the roll gap d to more than 0.0 mm and not more than 0.5 mm, for example. The surface speed ratio of the rolls is the same as for thermoplastics. The thin threading step of the second mixing step defibrates the carbon nanotubes by utilizing the moderate elasticity and moderate viscosity of the main agent.

After kneading the main agent and carbon nanotubes, a curing agent (for example, polyamidoamine) is added, and kneaded again under the same method and conditions as in the case of the main agent to uniformly mix the curing agent. . After that, molding (pressing, compression molding, extrusion molding, etc.) is performed, for example, it is cured by leaving it at room temperature for one day, and then post-baking (80 ° C., 15 hours) is performed to obtain a composite material.

2.1.4. Composite material (precursor)
In the composite material obtained by the second mixing step, the carbon nanotubes are dispersed in the macromolecular substance in a fibrillated state. The composite resulting from the second mixing step may be free of carbon nanotube bundles or agglomerates having a maximum width of 1 μm or greater.

In general, a plurality of single-walled carbon nanotubes are bundled together to form a bundle unless the carbon nanotube is defibrated. Also in the case of multi-walled carbon nanotubes, the fibers are entangled to form a pill-like aggregate. A composite material using single-walled carbon nanotubes has no bundles with a maximum width of 1 μm or more, and a composite material using multi-walled carbon nanotubes has no agglomerates with a maximum width of 1 μm or more. The maximum width of the bundle is the maximum width of the bundled fibers in the direction perpendicular to the longitudinal direction when viewed under a microscope. The maximum width of the agglomerate is the maximum width of the agglomerate in the microscopic view.

The composite material obtained by the second mixing step can be a composite material containing carbon nanotubes with an average diameter of 0.4 nm to 15.0 nm in the thermoplastic resin or rubber component. The composite material contains 5.0 parts by mass or more and 40.0 parts by mass or less of carbon nanotubes with respect to 100 parts by mass of thermoplastic resin or 100 parts by mass of a rubber component, which are polymeric substances.

2.2. Third Mixing Step In the third mixing step, the composite material obtained in the second step is used as a "precursor", and the precursor is further mixed with a polymer substance to obtain a composite material. In the third mixing step, the polymeric material in the second mixing step is called the first polymeric substance, and the polymeric substance in the third mixing step is called the second polymeric substance. The first polymeric substance and the second polymeric substance may be the same type of polymeric substance or different types of polymeric substances.

A third mixing step may mix the precursor with a second polymeric material to adjust the concentration of carbon nanotubes in the composite. In the third mixing step, similarly to the second mixing step, a high shearing force is applied to the second polymer substance, and the elastic restoring force of the second polymer substance is used to fibrillate the carbon nanotubes to form the second polymer. Composite materials can be produced that are dispersed in a substance. That is, in the third mixing step, as shown in FIG. 3, the precursor 32 is used instead of the polymer 30 of FIG. 2, and the second polymer 31 is used instead of the carbon nanotube-containing composition 80. knead with Therefore, in the explanation of the third mixing step, the explanation that overlaps with the second mixing step is omitted.

At least one or more of the thermoplastic resin, thermosetting resin, and rubber component mentioned in the second mixing step can be selected as the second polymer substance.

2.2.1. Third Mixing Step Using Thermoplastic Resin The third mixing step when the first polymer substance and the second polymer substance are thermoplastic resins will be described.

In the third mixing step, the content of the polyhydric alcohol in the precursor is less than 400.0 parts by mass with respect to 100 parts by mass of the thermoplastic resin, and the content of the carbon nanotubes in the composite material is 100 parts by mass of the thermoplastic resin. It can be 0.1 parts by mass or more and 15.0 parts by mass or less. In the third mixing step, processing is possible as long as the polyhydric alcohol is less than 400.0 parts by mass. Since the content of carbon nanotubes in the composite material can be reduced by the second polymer substance in the third mixing step, the content of carbon nanotubes can be appropriately set according to the application of the composite material.

2.2.2. Third Mixing Step Using Rubber Component The third mixing step when the first polymeric substance and the second polymeric substance are rubber components will be described.

In the third mixing step, the content of polyhydric alcohol in the precursor is 200.0 parts by mass or less per 100 parts by mass of the rubber component, and the content of carbon nanotubes in the composite material is 0.1 parts by mass or more and 30.0 parts by mass or less. In the third mixing step, processing is possible as long as the polyhydric alcohol is 200.0 parts by mass or less. Since the content of carbon nanotubes in the composite material can be reduced by the second polymer substance in the third mixing step, the content of carbon nanotubes can be appropriately set according to the application of the composite material.

3. Composite materials 3.1. Composite Material Using Thermoplastic Resin The composite material obtained by the third mixing step is a composite material containing carbon nanotubes with an average diameter of 0.4 nm to 15.0 nm in a thermoplastic resin. The composite material contains 0.1 parts by mass or more and 40.0 parts by mass or less of carbon nanotubes with respect to 100 parts by mass of the thermoplastic resin. The composite material comprises a thermoplastic resin reinforced with small average diameter carbon nanotubes and does not contain bundles or agglomerates of said carbon nanotubes with a maximum width greater than 1 μm.

The composite material obtained by the second mixing step or the third mixing step has a coefficient of variation (standard deviation / average value) of elongation at break measured in accordance with JIS K 6251 of 0.4 or less, and a thermoplastic resin The rate of change in breaking elongation with respect to the breaking elongation in a simple substance can be -99.0% or more. The "coefficient of variation" here is expressed as [CV = (σ/x)] by dividing the standard deviation (σ) by the arithmetic mean (x). is. The number of samples (n) for calculating the coefficient of variation CV of elongation at break is desirably at least 5 or more.

In addition, the composite material obtained by the second mixing step or the third mixing step exhibits a yield phenomenon in a tensile test measured in accordance with JIS K 6251, and the yield stress in the composite material with respect to the yield stress in the thermoplastic resin alone can be 1.0% or more.

In addition, the composite material obtained by the second mixing step or the third mixing step is stored at room temperature in a dynamic viscoelasticity test in accordance with JIS K 7244 at a dynamic strain of ± 0.05% and a frequency of 1 Hz. The elastic modulus (E') may be 0.5% or more greater than the storage elastic modulus (E') of the thermoplastic resin alone in the same test.

In addition, the composite material obtained by the second mixing step or the third mixing step using a thermoplastic resin as a polymer substance has a melting point of the thermoplastic resin or higher (in the case of a thermoplastic resin having no melting point, a glass transition point or higher). ) can be extruded through a 0.2 mm diameter nozzle. If the composite material can be extruded through a nozzle with a diameter of 0.2 mm, the composite material can be used as a raw material for injection molding or extrusion to form a product reinforced with carbon nanotubes.

3.2. Composite Material Using Rubber Component The composite material obtained by the third mixing step is a composite material containing carbon nanotubes with an average diameter of 0.4 nm to 15.0 nm in the rubber component. The composite material contains 0.1 parts by mass or more and less than 40.0 parts by mass of carbon nanotubes with respect to 100 parts by mass of the rubber component. The composite does not contain bundles or agglomerates of said carbon nanotubes with a maximum width of 1 μm or more.

The composite reinforces the rubber component with small average diameter carbon nanotubes and is free of carbon nanotube bundles or agglomerates with a maximum width greater than 1 μm. In addition, the composite material can be excellent in fatigue durability by defibrating fine carbon nanotubes and dispersing them in the rubber component.

A cross-linking agent is added to the composite material so that it can be cross-linked and molded into a rubber product of desired shape.

The present invention includes configurations that are substantially the same as the configurations described in the embodiments (configurations that have the same function, method and result, or configurations that have the same purpose and effect). Moreover, the present invention includes configurations obtained by replacing non-essential portions of the configurations described in the embodiments. In addition, the present invention includes a configuration that achieves the same effects or achieves the same purpose as the configurations described in the embodiments. In addition, the present invention includes configurations obtained by adding known techniques to the configurations described in the embodiments.

Examples of the present invention will be described below, but the present invention is not limited to these.

(A) Preparation of samples of Examples 1 to 12 (A-1) First mixing step As the first mixing step, carbon nanotubes ( "CNT-1" to "CNT-3" in the table) and a polyhydric alcohol ("DEG" in the table) were added and mixed with a spatula to obtain a mixture. The mixture was put into an open roll (two rolls) and kneaded for 10 minutes to obtain a carbon nanotube-containing composition (“CNT-containing composition” in the table). The open roll was set at a roll temperature of 23° C., a roll gap of 0.1 mm, and a roll speed ratio of 1.1. In the column of "Composition of CNT-containing composition" in the table, the mass ratio of the carbon nanotubes to the polyhydric alcohol is shown, so the mass parts of the polyhydric alcohol is shown when the blending amount of the carbon nanotubes is 1 mass part. Examples in which the first mixing step was carried out are marked with "o" in the "first mixing step" column of the table. Since the roll gap in the first mixing step to the third mixing step is a set value, the roll gap may slightly fluctuate in actual kneading, but the measured value was about 0.2 mm.

(A-2) Second mixing step As the second mixing step, the thermoplastic resin is wound around an open roll according to the formulation shown in the "precursor formulation" column of the table, and the carbon nanotubes obtained in the first mixing step are included. The composition was gradually added and kneaded to obtain an intermediate mixture, and the intermediate mixture was thinly passed several times (roll temperature: 160°C, roll spacing: 0.1 mm, roll speed ratio: 1.1) to obtain a precursor. Obtained. Further, the precursor was kneaded for 10 minutes with an open roll at 160° C. with a wider roll interval to evaporate the polyhydric alcohol contained in the precursor. For the examples in which the second mixing step was performed, "O" was entered in the "second mixing step" column of the table. A general drying oven or the like can also be used in the step of removing the polyhydric alcohol.

For the kneading temperature in the second mixing step, the DMA test was performed as described above. For example, the test results of Example 1 will be described. As shown in FIG. The logarithm value (log(E')) of , and the vertical axis on the right is the differential value (d(log(E'))/ dT), a graph was created, and the processing area manifestation temperature T2 to temperature T4 were obtained and set. Specifically, the graph of log(E') in FIG. 4 had an inflection point P1 at 162° C. (temperature T1). Next, from the graph of d (log (E')) / dT, the temperature range of the first region W1 with a constant slope is obtained, and the extrapolated tangent line L2 of the graph of log (E') and the inflection point P1 The temperature at the intersection point P2 with the tangent line L1 of the graph of log(E') was obtained as the processed region manifestation temperature T2 (148°C). Further, from the graph of d(log(E′))/dT, a range with a constant slope is defined as a second region W2, and an extrapolated tangent line L3 of log(E′) corresponding to this and log(E ') was determined as the flat region appearance temperature T3 (168° C.) at the intersection point P3 with the tangent line L1 of the graph. The temperature T4 (178°C), which is 1.06 times (T3°C x 1.06) the flat region appearance temperature T3 of the precursor sample of Example 1, was set as the upper limit of the kneading temperature.

From the results of temperature T1 to temperature T4 obtained in FIG. 4, by setting the kneading temperature in the second mixing step of Examples 1 to 12 to 160 ° C., it is possible to fall within the range of temperature T2 to temperature T4 in any formulation. Therefore, the kneading temperature in the first mixing step in Examples 1 to 12 was set to 160°C.

(A-3) Third mixing step As the third mixing step, the thermoplastic resin is wound around an open roll according to the formulation shown in the "Composite material formulation" column of the table, and the precursor obtained in the second mixing step is The mixture was gradually added and kneaded to obtain an intermediate mixture, and the intermediate mixture was thinly passed several times (roll temperature: 160°C, roll spacing: 0.1 mm, roll speed ratio: 1.1) to obtain a composite material. For the precursors of Examples 1, 6, 8 and 10, the third mixing step was not performed. For the examples in which the third mixing step was performed, "o" was entered in the "third mixing step" column of the table.

In Tables 1 to 8 (the same applies to Tables 9 to 12),
"CNT-1": Average diameter (A value obtained by arithmetically averaging measurements of 200 or more locations using scanning electron microscope imaging, the same applies hereinafter.) 5.0 nm (3 nm to 5 nm in the catalog value) Wall carbon nanotube (manufactured by Zeon Nano Technologies, grade name: SG101), “CNT-2”: Single-walled carbon nanotube (manufactured by OCSiAl, grade name: TUBALL) with an average diameter of 2.1 nm (1.5 nm in the catalog value) ,
"CNT-3": multi-walled carbon nanotubes (manufactured by Nanocyl, grade name: NC7000) with an average diameter of 10 nm (catalog value is 9.5 nm),
"DEG": manufactured by Wako Pure Chemical Industries, Ltd., diethylene glycol, special grade,
"PP": Polypropylene "F-300SP" manufactured by Prime Polymer Co., Ltd., having a melting point of 165°C.

In Tables 1 to 8, the blending amount of carbon nanotubes in the composite material and the precursor indicates parts by mass of carbon nanotubes when the thermoplastic resin (PP) is 100 parts by mass (phr). The amounts of each raw material in Tables 9 to 12 are the same as those in Tables 1 to 8 unless otherwise specified.

Molding process: The precursors of Examples 1, 6, 8, and 10 and the composite materials of Examples 2 to 5, 7, 9, 11, and 12 were hot-pressed at 220°C to form sheets. Each specimen was cut from the molded sheet.

(B) Preparation of samples of Comparative Examples 1 to 22 In Comparative Example 1, pellets of raw material PP were kneaded at 160 ° C. with a heated open roll, and then hot-pressed at 220 ° C. to form a sheet. . Each specimen was cut from the molded sheet.

In Comparative Examples 2 to 5, raw material PP pellets were wound around an open roll heated to 160 ° C., carbon nanotubes of the types shown in the table were added and kneaded, and then the roll interval was changed to 0.1 mm and thinly passed. The mixture was removed with The mixture taken out from the open roll was hot-pressed in the same manner as in Comparative Example 1 to obtain a test piece.

In Comparative Examples 6 to 8, the composite material of Comparative Example 5 was wound around an open roll heated to 160 ° C., and PP pellets were added and kneaded so that the "composite material formulation" shown in the table was obtained. The gap was changed to 0.1 mm, and the mixture was taken out. The mixture taken out from the open roll was hot-pressed in the same manner as in Comparative Example 1 to obtain a test piece.

In Comparative Example 9, carbon nanotubes were put into open rolls set to a roll temperature of 23° C., a roll interval of 0.1 mm, and a roll speed ratio of 1.1, and pulverized. Next, the raw material PP pellets are wound around an open roll heated to 160 ° C., 20 parts by mass of carbon nanotubes of the type shown in the table are added and kneaded, and the roll interval is changed to 0.1 mm. The mixture was removed with The mixture taken out from the open roll was hot-pressed in the same manner as in Comparative Example 1 to obtain a test piece.

In Comparative Example 10, the mixture obtained in Comparative Example 9 was wound around an open roll heated to 160 ° C., and PP pellets were added so that the amount shown in the "composite material composition" column in the table was added and kneaded. , the roll interval was changed to 0.1 mm, and the mixture was taken out. The mixture taken out from the open roll was hot-pressed in the same manner as in Comparative Example 1 to obtain a test piece.

In Comparative Example 11, carbon nanotubes and polyhydric alcohol were placed in a container and mixed with a spatula according to the "Formulation of CNT-containing composition" in the table. Next, the raw material PP pellets were wound around an open roll heated to 160° C., and 20 parts by mass of carbon nanotubes of the type shown in the table “precursor composition” were added and kneaded. The mixture was taken out by changing to 1 mm and passing through thinly. The mixture taken out from the open roll was hot-pressed in the same manner as in Comparative Example 1 to obtain a test piece.

In Comparative Example 12, the mixture obtained by evaporating the polyhydric alcohol in Comparative Example 11 was wound around an open roll heated to 160 ° C., and PP pellets were added so that the amount shown in the "Composition of composite material" column in the table. After kneading, the mixture was taken out by thinly passing the rolls at a roll interval of 0.1 mm. The mixture taken out from the open roll was hot-pressed in the same manner as in Comparative Example 1 to obtain a test piece.

In Comparative Example 13, a carbon nanotube-containing composition was obtained in the same steps as in Example 1 according to the "Formulation of CNT-containing composition" in the table. Next, the raw material PP pellets are wound around an open roll heated to 160 ° C., 20 parts by mass of carbon nanotubes of the type shown in the table "precursor blend" are added and kneaded to form a mixture (thinly passed through not included). Further, the mixture was kneaded for 10 minutes with an open roll having a roll interval of 1.0 mm and a temperature of 160° C. to evaporate the polyhydric alcohol contained in the mixture. The mixture taken out from the open roll was hot-pressed in the same manner as in Comparative Example 1 to obtain a test piece.

In Comparative Example 14, the mixture obtained by evaporating the polyhydric alcohol in Comparative Example 13 was wound around an open roll heated to 160 ° C., and PP pellets were added so that the amount shown in the "composite material composition" column of the table. After kneading, the mixture was taken out by thinly passing the rolls at a roll interval of 0.1 mm. The mixture taken out from the open roll was hot-pressed in the same manner as in Comparative Example 1 to obtain a test piece.

In Comparative Example 15, a carbon nanotube-containing composition was obtained in the same steps as in Example 1 according to the "Formulation of CNT-containing composition" in the table. Next, the raw material PP pellets were wound around an open roll heated to 160° C., and the carbon nanotube-containing composition was charged and kneaded according to the formulation shown in the table "precursor formulation". The mixture was taken out by changing to 1 mm and passing through thinly. Furthermore, the mixture was kneaded for 10 minutes with an open roll at 160° C. with a wider roll interval to evaporate the polyhydric alcohol contained in the mixture. The mixture taken out from the open roll was hot-pressed in the same manner as in Comparative Example 1 to obtain a test piece.

In Comparative Example 16, the mixture obtained by evaporating the polyhydric alcohol in Comparative Example 15 was wound around an open roll heated to 160 ° C., and PP pellets were added so that the amount shown in the "composite material composition" column of the table. After kneading, the mixture was taken out by thinly passing the rolls at a roll interval of 0.1 mm. The mixture taken out from the open roll was hot-pressed in the same manner as in Comparative Example 1 to obtain a test piece.

In Comparative Example 17, a carbon nanotube-containing composition was obtained in the same steps as in Example 1 according to the "Formulation of CNT-containing composition" in the table. Next, the raw material PP pellets are wound around an open roll heated to 160 ° C., and the carbon nanotube-containing composition is added and kneaded according to the formulation shown in the "precursor formulation" in the table to form a mixture (thinly passed through). not included). Further, the mixture was kneaded for 10 minutes with an open roll having a roll interval of 1.0 mm and a temperature of 160° C. to evaporate the polyhydric alcohol contained in the mixture. The mixture taken out from the open roll was hot-pressed in the same manner as in Comparative Example 1 to obtain a test piece.

In Comparative Example 18, the mixture obtained by evaporating the polyhydric alcohol in Comparative Example 17 was wound around an open roll heated to 160 ° C., and PP pellets were added so that the amount shown in the "composite material composition" column of the table. After kneading, the mixture was taken out by thinly passing the rolls at a roll interval of 0.1 mm. The mixture taken out from the open roll was hot-pressed in the same manner as in Comparative Example 1 to obtain a test piece.

Comparative Example 19 is the same test piece as Comparative Example 1.

For Comparative Example 20, a test piece was obtained by the same steps as Comparative Examples 2 to 4 according to the "composite material formulation" in the table. In Comparative Example 20, "CNT-2" was blended instead of "CNT-1".

For Comparative Examples 21 and 22, test pieces were obtained in the same steps as in Comparative Examples 2 to 4 according to the "composite material composition" in the table. In Comparative Examples 21 and 22, "CNT-3" was blended instead of "CNT-1".

(C) Evaluation method (C-1) Tensile test For the samples of Examples and Comparative Examples, JIS K7161 1BA dumbbell test pieces were measured using a Shimadzu Autograph AG-X tensile tester, 23 ± 2 A tensile test was performed based on JIS K7161 at ° C., a standard line distance of 25 mm, and a tensile speed of 50 mm / min, tensile strength (TS (MPa)), elongation at break (Eb (%)), and tensile yield stress (σ (MPa)) was measured, and the average values of n = 5 are shown in Tables 1 to 8. Furthermore, the coefficient of variation of elongation at break (“Eb coefficient of variation”) was obtained from this average value, and the values are shown in the “Eb coefficient of variation” column of Tables 1 to 8, respectively. Further, the value obtained by subtracting the average breaking elongation (813%) of the thermoplastic resin alone serving as the matrix (Comparative Example 1) from the average breaking elongation of each example was It was divided by the average value of elongation, and the values are shown in the column of "Eb change rate" in Tables 1 to 8, respectively. In addition, the value obtained by subtracting the average tensile yield stress (25.9 MPa) of the thermoplastic resin alone serving as the matrix from the average tensile yield stress of each example was calculated as the tensile yield stress of the thermoplastic resin alone. , and the values are shown in the column of "σy change rate" in Tables 1 to 8, respectively. The samples of Examples 1, 6, 8, 10 and Comparative Examples 9, 11, 13, 15, 17, which were not subjected to the third step, were not subjected to the tensile test.

(C-2) DMA Test For the samples of Examples and Comparative Examples, a test piece cut into a rectangular shape (40 × 4 × press sheet thickness mm) was used with a dynamic viscoelasticity tester DMS7100 manufactured by Hitachi High-Tech Science. DMA test (dynamic viscoelasticity test) based on JIS K 7244 at a distance between chucks of 20 mm, a measurement temperature of -60 to 400°C, a heating pace of 1.5°C, a dynamic strain of ±0.05%, and a frequency of 1 Hz. was performed to measure the storage modulus (E').

From the DMA test results, the storage elastic modulus (E') at a measurement temperature of 25°C was measured, and the average values of n = 5 are shown in Tables 1 to 8. Furthermore, the variation coefficient of the storage modulus (E') ("E' variation coefficient") was obtained from this average value. Furthermore, from this average value, the coefficient of variation of the storage modulus (E') ("E' coefficient of variation") was obtained, and the values are shown in the column of "E' coefficient of variation" in Tables 1 to 8, respectively. In addition, regarding the average value of the storage elastic modulus at 25 ° C., the average value of each example is divided by the average value (1.95 GPa) of the thermoplastic resin alone (Comparative Example 1) serving as the matrix, and the values are shown in Tables 1 to 1. It is shown in the column of "E' change rate" in Table 8. The samples of Examples 1, 6, 8, and 10 and Comparative Examples 9, 11, 13, 15, and 17, which were not subjected to the third step, were not subjected to the DMA test.

(C-3) Evaluation of defibrillation performance Evaluation of fibrillation performance of the composite material was performed on the sheet-shaped samples of Examples and Comparative Examples molded to a thickness of 0.5 mm to 0.8 mm. Each sample was observed under an optical microscope or scanning electron microscope. In observation with a scanning electron microscope, the sheet-like sample was cooled with liquid nitrogen, and the cut surface was observed when the sample was cut. Tables 1 to 8 show the evaluation results ("absence" means no bundles or aggregates with a maximum width of 1 μm or more, and "yes" means there are bundles or aggregates with a maximum width of 1 μm or more). 5 shows a low-magnification optical micrograph of Example 2, FIG. 6 shows a low-magnification optical micrograph of Example 11, and FIG. 10 shows an electron micrograph of Example 5. 7 shows a low-magnification optical micrograph of Comparative Example 2, FIG. 8 shows a low-magnification optical micrograph of Comparative Example 6, FIG. 9 shows a low-magnification optical micrograph of Comparative Example 20, and FIG. is an electron micrograph of Comparative Example 4, and FIG. 12 is an electron micrograph of Comparative Example 8. The black parts in FIGS. 7 to 9 are agglomerates, and the bundles with a maximum width of 32 μm are surrounded by the dashed ellipse in FIG. 11, and the bundles with a maximum width of 5 μm are surrounded by the dashed ellipse in FIG. be.

(C-4) Evaluation of Extrusion Moldability The samples of Examples and Comparative Examples were evaluated for extrusion moldability based on whether or not they could be extruded from a nozzle with a diameter of 2 mm using an extruder. The nozzle temperature during extrusion was 220° C., which is the same as the heat press. The evaluation results are shown in Tables 1 to 8 as "passable" when extrusion molding is possible and "fail" when extrusion molding is not possible.

(D) Evaluation The samples of Examples 1 to 12 were free of bundles and agglomerates of carbon nanotubes with a maximum width of 1 μm or greater. In contrast, the samples of Comparative Examples 2-18 and Comparative Examples 20-22 had carbon nanotube bundles with a maximum width of 1 μm or more.

Also, the samples of Examples 1 to 12 could be extruded through a nozzle with a diameter of 0.2 mm.

The samples of Examples 1 to 12 have a coefficient of variation (standard deviation/average value) of elongation at break of 0.4 or less, and the breaking elongation of the thermoplastic resin alone (Comparative Examples 1 and 19) The rate of change in elongation was -99.0% or more. In contrast, none of the samples of Comparative Examples 1 to 22 satisfied both the coefficient of variation of elongation at break and the change rate of elongation at break.

In the samples of Examples 1 to 12, the storage elastic modulus (E') of the composite material at room temperature in the dynamic viscoelasticity test is higher than the storage elastic modulus of the same test in the thermoplastic resin alone (Comparative Examples 1 and 19). It was greater than (E') by 0.5% or more.

The samples of Examples 1 to 12 exhibit a yield phenomenon in the tensile test, and the rate of change in the yield stress of the composite material relative to the yield stress of the thermoplastic resin alone (Comparative Examples 1 and 19) is 1.0% or more. Met.

(E) Preparation of samples of Examples 13-19 and Comparative Examples 23-29 A mixing step and a second mixing step were performed to obtain a precursor. Further, using this test piece, a molding step was performed in the same manner as in Example 1 to obtain a test piece. The roll temperature in the second mixing step and the third mixing step in Examples 13 to 17 and Comparative Examples 23 to 27 was set to 130° C. between the temperature T3 and the temperature T4 determined by the DMA test conducted in advance. ,
The mold temperature in the molding process was set at 180°C.

In Examples 14 and 15, composite materials were obtained by performing the third mixing step in the same manner as in Example 2 using the precursor of Example 13 in accordance with the "Formulation of composite material" in the table. Furthermore, using the composite material of each example, a molding step was performed in the same manner as in Example 2 to obtain a test piece.

In Comparative Example 23, raw material PE pellets were kneaded at 130° C. with a heated open roll, and then hot-pressed at 180° C. to obtain a test piece.

In Comparative Examples 24 and 25, raw material PE pellets were wound around an open roll heated to 130° C., carbon nanotubes of the types shown in the table were charged and kneaded, and then the roll interval was changed to 0.1 mm and thinly passed. The mixture was removed with The mixture taken out from the open roll was hot-pressed in the same manner as in Comparative Example 23 to obtain a test piece.

In Example 16, a precursor was obtained by carrying out the same first mixing step and second mixing step as in Example 1 according to "Formulation of CNT-containing composition" and "Formulation of precursor" in the table. Further, using this test piece, a molding step was performed in the same manner as in Example 1 to obtain a test piece.

In Example 17, a composite material was obtained by performing the third mixing step in the same manner as in Example 2 using the precursor of Example 16 according to the "composite material formulation" in the table. Further, using the composite material of Example 17, a molding step was performed in the same manner as in Example 2 to obtain a test piece.

In Comparative Example 26, pellets of Re-PE as a raw material were kneaded at 130° C. with a heated open roll, and then hot-pressed at 180° C. to obtain a test piece.

In Comparative Example 27, the raw material Re-PE pellets were wound around an open roll heated to 130 ° C., the types of carbon nanotubes shown in the table were added and kneaded, and then the roll interval was changed to 0.1 mm and thinly passed. The mixture was removed with The mixture taken out from the open roll was hot-pressed in the same manner as in Comparative Example 26 to obtain a test piece.

In Example 18, a precursor was obtained by carrying out the same first mixing step and second mixing step as in Example 1 in accordance with "Formulation of CNT-containing composition" and "Formulation of precursor" in the table. Further, using this test piece, a molding step was performed in the same manner as in Example 1 to obtain a test piece. In addition, the roll temperature in the second mixing step and the third mixing step in Examples 18 and 19 and Comparative Examples 28 and 29 was set to 170° C. between the temperature T3 and the temperature T4 obtained by the DMA test performed in advance. , the mold temperature in the molding process was set to 220°C.

In Example 19, a composite material was obtained by performing the third mixing step in the same manner as in Example 2 using the precursor of Example 18 according to the "composite material formulation" in the table. Further, using the composite material of Example 19, a molding step was performed in the same manner as in Example 2 to obtain a test piece.

In Comparative Example 28, pellets of raw material Re-PP were kneaded at 170° C. with a heated open roll and then hot-pressed at 220° C. to obtain a test piece.

In Comparative Example 29, the raw material Re-PP pellets were wound around an open roll heated to 170 ° C., and the carbon nanotubes of the types shown in the table were added and kneaded, and then the roll interval was changed to 0.1 mm and thinly passed. The mixture was removed with The mixture taken out from the open roll was hot-pressed in the same manner as in Comparative Example 28 to obtain a test piece.

In Tables 9 to 11,
"LLDPE": manufactured by Eastern Petrochemical Company, linear low density polyethylene QAMAR FC21HS, melting point 122°C;
"Re-PE": Recycled plastic with a melting point of 131 ° C., 90% by mass of the resin component being polyethylene and polypropylene components, and 80% by mass of it being polyethylene (selected and pelletized by Toyama Environmental Improvement Co., Ltd. material),
"Re-PP": Recycled plastic with a melting point of 163 ° C., 90% by mass of the resin component being polyethylene and polypropylene components, and 82% by mass of that being polypropylene (selected and pelletized by Toyama Environmental Improvement Co., Ltd. material),
Met.

Each sample was evaluated according to the above "(C) Evaluation method", and the evaluation results are shown in Tables 9 to 11.

(F) Evaluation The samples of Examples 13-19 were free of carbon nanotube bundles and agglomerates with a maximum width of 1 μm or greater. In contrast, the samples of Comparative Examples 24, 25, 27, and 29 had carbon nanotube bundles with a maximum width of 1 μm or more.

Also, the samples of Examples 14, 15, 17 and 19 could be extruded through a nozzle with a diameter of 0.2 mm.

The samples of Examples 14, 15, 17, and 19 had a coefficient of variation (standard deviation/average value) of elongation at break of 0.4 or less, and the rate of change in elongation at break with respect to the elongation at break of the thermoplastic resin alone was −99.0% or more. In contrast, none of the samples of Comparative Examples 23 to 29 satisfied both the coefficient of variation of elongation at break and the change rate of elongation at break.

In the samples of Examples 14, 15, 17, and 19, the storage elastic modulus (E') of the composite material at room temperature in the dynamic viscoelasticity test is higher than the storage elastic modulus (E') of the same test in the thermoplastic resin alone. was also greater than 0.5%.

The samples of Examples 14, 15, 17, and 19 showed a yield phenomenon in the tensile test, and the rate of change of the yield stress of the composite material relative to the yield stress of the thermoplastic resin alone was 1.0% or more.

(G) Preparation of samples of Examples 20 and 21 and Comparative Examples 30 and 31 The samples of Example 20 were first mixed in the same manner as in Example 1 according to the "Formulation of CNT-containing composition" in the table. A carbon nanotube-containing composition was obtained. Next, in the second mixing step, NBR as a rubber component is wound around an open roll according to the formulation shown in the "precursor formulation" column of the table, and the carbon nanotube-containing composition obtained in the first mixing step is applied to the NBR. It was gradually added and thinly passed five times (roll temperature: 30°C, roll interval: 0.1 mm, roll speed ratio: 1.1) to obtain a precursor. Furthermore, for the sample of Example 21, as the third mixing step, NBR and the precursor obtained in the second mixing step were wound around an open roll according to the formulation shown in the column "Composite material formulation" in the table, An intermediate mixture was obtained by kneading, and the intermediate mixture was thinly passed several times (roll temperature: 30°C, roll interval: 0.1 mm, roll speed ratio: 1.1) to obtain a composite material. The composite material thus obtained was vacuum dried (120° C., 8 hours) to evaporate the polyhydric alcohol from the composite material. Furthermore, 3.2 parts by mass of a cross-linking agent was added to the composite material of Example 21, kneaded, cross-linked at 165° C. for 30 minutes, and a test piece was cut out from the cross-linked composite material.

For the sample of Comparative Example 30, 3.2 parts by mass of a cross-linking agent was added to NBR, kneaded, cross-linked at 165° C. for 30 minutes, and a test piece was cut out from the cross-linked NBR.

For the sample of Comparative Example 31, carbon nanotubes were added to NBR wound around an open roll and mixed at room temperature according to the "Formulation of CNT-containing composition" in the table. C. for 30 minutes, and specimens were cut from the crosslinked composite material.

In Table 12, "NBR": carboxy-modified acrylonitrile-butadiene rubber, Nipol NX775 manufactured by Nippon Zeon Co., Ltd., acrylonitrile content of 26.7%.

Each sample was evaluated according to the above "(C) Evaluation method" except for "Extrudability", and the evaluation results are shown in Table 12.

(H) Evaluation The samples of Examples 20 and 21 had no bundles or agglomerates of carbon nanotubes with a maximum width of 1 μm or more. In contrast, the sample of Comparative Example 31 had a bundle of carbon nanotubes with a maximum width of 1 μm or more.

The sample of Example 21 had a coefficient of variation of elongation at break (standard deviation/average value) of 0.4 or less, and a rate of change in elongation at break relative to the elongation at break of the rubber component alone was -99.0% or more. there were. In contrast, none of the samples of Comparative Example 31 satisfied both the coefficient of variation of elongation at break and the change rate of elongation at break.

2... open roll, 10... first roll, 20... second roll, 30... polymer substance, 31... second polymer substance, 32... precursor, 34... bank, 40... non-contact thermometer, 80... carbon Nanotube-containing composition

Claims (6)

A mixture containing carbon nanotubes having an average diameter of 0.4 nm to 15.0 nm and a polyhydric alcohol is pressurized and compressed, and then the pressure is released or reduced to restore the original volume to obtain a carbon nanotube-containing composition. including a mixing step to obtain
The method for producing a carbon nanotube-containing composition, wherein the blending amount of the polyhydric alcohol is 1.0 parts by mass or more and less than 10.0 parts by mass with respect to 1.0 parts by mass of the carbon nanotubes. In claim 1,
The method for producing a carbon nanotube-containing composition, wherein the polyhydric alcohol includes at least one of dihydric alcohol and trihydric alcohol. A method for producing a composite material using the carbon nanotube-containing composition obtained in claim 1 or claim 2,
The mixing step is a first mixing step,
further comprising a second mixing step of mixing the carbon nanotube-containing composition obtained in the first mixing step with a polymeric substance to obtain a composite material;
The method for producing a composite material, wherein the content of the carbon nanotubes in the composite material is 5.0 parts by mass or more and 40.0 parts by mass or less with respect to 100 parts by mass of the polymer substance. A method for producing a composite material using the carbon nanotube-containing composition obtained in claim 1 or claim 2,
The mixing step is a first mixing step,
a second mixing step of mixing the carbon nanotube-containing composition obtained in the first mixing step with a first polymeric substance to obtain a precursor;
a third mixing step of further mixing the precursor with the second polymeric substance to obtain the composite material;
A method of manufacturing a composite material, further comprising: In claim 4,
The first polymeric substance and the second polymeric substance are thermoplastic resins,
The content of the polyhydric alcohol in the precursor is less than 400.0 parts by mass with respect to 100 parts by mass of the thermoplastic resin,
The method for producing a composite material, wherein the content of the carbon nanotubes in the composite material is 0.1 parts by mass or more and 15.0 parts by mass or less with respect to 100 parts by mass of the thermoplastic resin. In claim 4,
The first polymeric substance and the second polymeric substance are rubber components,
The method for producing a composite material, wherein the content of the carbon nanotubes in the composite material is 0.1 parts by mass or more and 40.0 parts by mass or less with respect to 100 parts by mass of the rubber component.

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