WO2023162899A1

WO2023162899A1 - Method for producing composite resin particles, antistatic composition, and molded object

Info

Publication number: WO2023162899A1
Application number: PCT/JP2023/005869
Authority: WO
Inventors: 篤史高柳; 慶久武山
Original assignee: 日本ゼオン株式会社
Priority date: 2022-02-28
Filing date: 2023-02-17
Publication date: 2023-08-31

Abstract

A method for producing composite resin particles which includes a pulverization step in which a composite resin material comprising carbon nanotubes and a fluororesin is pulverized. The composite resin material has a carbon nanotube content C^CNT (mass%) of 0.015-0.200 mass%. In the pulverization step, the composite resin material is pulverized by the rotation of rotating blades so that the value of D/C^CNT, obtained by dividing the movement distance D (m) of the rotating blades by the C^CNT (mass%), is 1,000-110,000 m/mass%.

Description

Method for producing composite resin particles, antistatic composition, and molded article

TECHNICAL FIELD The present invention relates to a method for producing composite resin particles, an antistatic composition, and a molded article, and in particular, a method for producing composite resin particles containing a fluororesin and a carbon nanotube, an antistatic composition, and a molded article. It is about.

BACKGROUND ART Carbon nanotubes (hereinafter sometimes referred to as “CNT”) are excellent in electrical conductivity, thermal conductivity, sliding properties, mechanical properties, etc., and thus their application to a wide range of applications has been investigated.
Therefore, in recent years, by taking advantage of the excellent properties of CNT and combining resin materials with CNT, we have provided a composite resin material that combines the properties of resin such as workability and strength and the properties of CNT such as conductivity. Technology development is underway.

For example, in Patent Document 1, when preparing a slurry containing a fluororesin, a fibrous carbon nanostructure, and a dispersion medium and removing the dispersion medium from the obtained slurry to obtain a composite resin material, the composite resin A production method for producing a composite resin material through a step of forming a material into particles having a predetermined particle size distribution is disclosed. Further, for example, Patent Document 2 discloses a fluororesin molded article containing a fluororesin and a specific amount of carbon nanotubes, wherein the arithmetic surface roughness (Ra) is within a specific range, and its manufacture. A method is disclosed.

WO2018/066433 WO2021/166743

However, in the method for producing a resin material disclosed in Patent Document 1 and Patent Document 2, etc., the yield at the time of manufacturing the resin material is increased, and the electrical resistance when the manufactured resin material is formed into a molded body is reduced. In that respect, there was room for improvement.

Accordingly, an object of the present invention is to produce, at a high yield, composite resin particles capable of forming a molded body with low electrical resistance.

The inventor of the present invention has made intensive studies to achieve the above object. Then, the present inventor found that in a method for producing composite resin particles, which includes a pulverization step of pulverizing a composite resin material containing carbon nanotubes and a fluororesin, the content ratio of CNTs in the composite resin material is set within a predetermined range. , When the composite resin material is pulverized by rotating the rotor blades in the pulverization step, the value of D/C ^CNT , which is the value obtained by dividing the moving distance D (m) of the rotor blades by C ^CNT (% by mass), is 1, It was newly discovered that by making the amount of 000 m/mass% or more and 110,000 m/mass% or less, composite resin particles capable of forming a molded article with low electrical resistance can be produced at a high yield. , completed the present invention.

[1] That is, an object of the present invention is to advantageously solve the above problems, and a method for producing composite resin particles of the present invention comprises pulverizing a composite resin material containing carbon nanotubes and a fluororesin. wherein the carbon nanotube content C ^CNT (% by mass) of the composite resin material is 0.015% by mass or more and 0.200% by mass or less; In the step, when the composite resin material is pulverized by rotating the rotor blades, the value obtained by dividing the moving distance D (m) of the rotating blades by the C ^CNT (% by mass) is D/moving distance D of the rotor blades. is 1,000 m/mass % or more and 110,000 m/mass % or less. According to such a production method of the present invention, composite resin particles capable of forming a compact having low electrical resistance can be produced at a high yield.

[2] Here, in the method for producing composite resin particles of [1] above, the carbon purity of the carbon nanotubes is preferably 99% or more. By using carbon nanotubes with a carbon purity of 98.0% or more, the electrical resistance of the resulting molded article can be further reduced.
The carbon purity of carbon nanotubes can be obtained from elemental analysis using fluorescent X-rays, thermogravimetric analysis (TGA), or the like.

[3] In the method for producing composite resin particles of [1] or [2] above, it is preferable that the carbon nanotubes include single-walled carbon nanotubes. By using single-walled CNTs, the electrical resistance of the resulting compact can be further reduced.

[4] Here, the antistatic composition of the present invention is characterized by comprising composite resin particles produced by the method for producing composite resin particles according to any one of [1] to [3] above. [5] Further, the molded article of the present invention is characterized by molding composite resin particles produced by the method for producing composite resin particles according to any one of [1] to [3] above.

According to the present invention, composite resin particles capable of forming a compact with low electrical resistance can be produced at a high yield.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail.
Here, the method for producing composite resin particles of the present invention is used when producing composite resin particles containing carbon nanotubes and fluororesin. The composite resin particles produced by the method for producing composite resin particles of the present invention are used in producing the antistatic composition of the present invention. Furthermore, composite resin particle molded bodies produced by the method for producing composite resin particles of the present invention can be used, for example, as parts of semiconductor manufacturing equipment, chemical liquid tanks, wafer cleaning containers, cleaning nozzles, antistatic sheets, and for integrated circuits. They are useful as trays, wafer carriers, chemical hoses, piping joints, diaphragms, sealing materials, and the like.

(Method for producing composite resin particles)
The method for producing composite resin particles of the present invention is a method for producing composite resin particles including a pulverizing step of pulverizing a composite resin material containing carbon nanotubes and fluororesin. Here, the composite resin material has a carbon nanotube content C ^CNT (% by mass) of 0.015% by mass or more and 0.200% by mass or less. Further, in the pulverization step, when the composite resin material is pulverized by rotating the rotor blades, the value of D/C ^CNT , which is the value obtained by dividing the moving distance D (m) of the rotor blades by C ^CNT (% by mass), is It is 1,000 m/mass % or more and 110,000 m/mass % or less. Furthermore, in the method for producing composite resin particles of the present invention, prior to the pulverization step, a mixing step of mixing the fluororesin, CNTs, a dispersion medium, and optional additives, and a drying step are carried out, It is preferable to form a predetermined composite resin material.

Then, according to the method for producing composite resin particles of the present invention, composite resin particles capable of forming a compact with low electrical resistance can be produced at a high yield. The reason for this is not clear, but by pulverizing a composite resin material that satisfies a predetermined CNT content under conditions such that the moving distance of the rotor blades with respect to the CNT content is within a predetermined range, it is possible to obtain a suitable strength. can be applied to the composite resin material, the structure of the CNTs blended as a material is not excessively damaged, and uniform particles are formed, so the composite with low electrical resistance It is presumed that this is because resin particles can be formed at a high yield.

<Mixing process>
In the mixing step, the fluororesin, CNTs, dispersion medium, and optional additives are mixed to prepare a slurry.

[Fluororesin]
Examples of fluororesins include polytetrafluoroethylene (PTFE), tetrafluoroethylene perfluoroalkylvinyl ether copolymer (PFA), tetrafluoroethylene hexafluoropyrrylene copolymer (FEP), and tetrafluoroethylene ethylene copolymer. (ETFE), polychlorotrifluoroethylene (PCTFE), chlorotrifluoroethylene ethylene copolymer (ECTFE), polyvinylidene fluoride (PVDF) and polyvinyl fluoride (PVF). Among them, PTFE or PFA is preferable as the fluororesin, and PTFE is more preferable. In addition, these may be used individually by 1 type, and may use 2 or more types together.

Here, the fluororesin used in the mixing step is preferably fluororesin particles. The fluororesin particles are excellent in dispersibility in slurry. Therefore, if the fluororesin particles are used, the CNTs can be well dispersed in the fluororesin matrix of the composite resin particles to be obtained, and the conductivity of the composite resin particles to be obtained can be further improved.

The average particle size of the fluororesin particles is preferably 1 μm or more, more preferably 5 μm or more, still more preferably 10 μm or more, preferably 700 μm or less, and 250 μm or less. is more preferable, and 150 μm or less is even more preferable. By setting the average particle size of the fluororesin particles to 1 μm or more, the dispersibility of the CNTs in the slurry can be further enhanced. In addition, by setting the average particle size of the fluororesin particles to 700 μm or less, the productivity of the slurry can be improved.
In the present invention, the "average particle size" of the fluororesin particles is obtained by measuring the particle size distribution (volume basis) by a laser diffraction method and calculating the particle size at which the cumulative volume frequency is 50%. can be done.

Furthermore, the amount of the fluororesin compounded in the slurry (100% by mass) is preferably 1% by mass or more, more preferably 3% by mass or more, and preferably 30% by mass or less, and 25% by mass. % or less. If the blending amount of the resin particles is within the above range, the dispersibility of the fluororesin and CNTs in the slurry can be enhanced, and the conductivity of the obtained composite resin particles can be further improved.

[carbon nanotube]
Single-walled carbon nanotubes and/or multi-walled carbon nanotubes can be used as carbon nanotubes, but CNTs preferably include single-walled to 5-walled carbon nanotubes, more preferably single-walled carbon nanotubes. . If the CNTs contain single-walled carbon nanotubes, the conductivity of the resulting composite resin particles can be further improved.

Here, the CNT preferably has a carbon purity of 98.0% by mass or more, more preferably 99.0% by mass or more, and even more preferably 99.5% by mass or more. If the carbon purity of CNT is at least the above lower limit, the electrical resistance of the obtained composite resin particles and molded article can be further reduced.

The average diameter of CNTs is preferably 1 nm or more, preferably 60 nm or less, more preferably 30 nm or less, and even more preferably 10 nm or less. When the average diameter of the CNTs is 1 nm or more, the dispersibility of the CNTs can be enhanced, and properties such as electrical conductivity can be stably imparted to the composite resin particles and molded articles. Further, when the average diameter of CNTs is 60 nm or less, properties such as conductivity can be efficiently imparted to the composite resin particles and molded article even when the amount of the CNTs is small.
In the present invention, the "average diameter of CNTs" is obtained by measuring the diameter (outer diameter) of 20 CNTs on a transmission electron microscope (TEM) image and calculating the number average value. be able to.

In addition, the CNT has a ratio (3σ/Av) of more than 0.20 and less than 0.60 to the average diameter (Av) of the value (3σ) obtained by multiplying the standard deviation of the diameter (σ: sample standard deviation) by 3. CNTs are preferably used, more preferably CNTs with 3σ/Av greater than 0.25, and even more preferably CNTs with 3σ/Av greater than 0.40. Using CNTs with a 3σ/Av of more than 0.20 and less than 0.60 can further improve the performance of the produced composite resin particles and molded articles.
The average diameter (Av) and standard deviation (σ) of CNTs may be adjusted by changing the CNT manufacturing method or manufacturing conditions, or by combining multiple types of CNTs obtained by different manufacturing methods. You may

As the CNT, the diameter measured as described above is plotted on the horizontal axis and the frequency is plotted on the vertical axis, and when Gaussian approximation is performed, a normal distribution is usually used.

The average length of the CNTs is preferably 10 µm or more, more preferably 50 µm or more, even more preferably 80 µm or more, preferably 600 µm or less, and preferably 550 µm or less. More preferably, it is 500 μm or less. If the average length is 10 μm or more, the conductive paths can be well formed in the composite resin particles and the molded article, and the dispersibility can be improved. Further, when the average length is 600 μm or less, the conductivity of the composite resin particles and the molded article can be stabilized. Therefore, if the average length of CNTs is within the above range, the surface resistivity of the compact can be sufficiently reduced.
In the present invention, the average length of CNTs can be obtained by measuring the length of 20 CNTs on a scanning electron microscope (SEM) image and calculating the number average value.

Furthermore, CNTs usually have an aspect ratio of more than 10. In addition, the aspect ratio of CNT is determined by measuring the diameter and length of 100 randomly selected CNTs using a scanning electron microscope or a transmission electron microscope. It can be obtained by calculating the average value.

In addition, the CNT preferably has a BET specific surface area of 200 m ² /g or more, more preferably 400 m ² /g or more, even more preferably 600 m ² /g or more, and 2000 m ² /g or less. is preferably 1800 m ² /g or less, and even more preferably 1600 m ² /g or less. If the BET specific surface area of the CNTs is 200 m ² /g or more, the dispersibility of the CNTs can be enhanced, and properties such as electrical conductivity of the composite resin particles and molded article can be sufficiently enhanced with a small blending amount. Further, when the BET specific surface area of CNTs is 2000 m ² /g or less, properties such as electrical conductivity of the composite resin particles and molded article can be stabilized.
In the present invention, the "BET specific surface area" refers to the nitrogen adsorption specific surface area measured using the BET method.

In addition, CNTs preferably show an upward convex shape in the t-plot obtained from the adsorption isotherm. The "t-plot" can be obtained by converting the relative pressure to the average thickness t (nm) of the nitrogen gas adsorption layer in the CNT adsorption isotherm measured by the nitrogen gas adsorption method. That is, the average thickness t of the nitrogen gas adsorption layer corresponding to the relative pressure is obtained from a known standard isotherm obtained by plotting the average thickness t of the nitrogen gas adsorption layer against the relative pressure P/P0, and the above conversion is performed. gives a t-plot of CNTs (t-plot method by de Boer et al.).

Here, the growth of a nitrogen gas adsorption layer on a substance having pores on its surface is classified into the following processes (1) to (3). Then, the slope of the t-plot changes due to the following processes (1) to (3).
(1) Formation of a monomolecular adsorption layer of nitrogen molecules on the entire surface (2) Formation of a multimolecular adsorption layer and subsequent capillary condensation filling process within the pores (3) Posterior pores filled with nitrogen Formation process of polymolecular adsorption layer on non-porous surface

Then, the t-plot showing an upwardly convex shape is located on a straight line passing through the origin in a region where the average thickness t of the nitrogen gas adsorption layer is small, whereas when t becomes large, the plot is on the straight line. position shifted downward from A CNT having such a t-plot shape has a large ratio of the internal specific surface area to the total specific surface area of the CNT, indicating that many openings are formed in the CNT.

The inflection point of the t-plot of CNT is preferably in the range that satisfies 0.2 ≤ t (nm) ≤ 1.5, and is in the range of 0.45 ≤ t (nm) ≤ 1.5. is more preferable, and it is even more preferable to be in the range of 0.55≦t(nm)≦1.0. If the inflection point of the t-plot of CNTs is within such a range, the dispersibility of CNTs can be enhanced, and properties such as electrical conductivity of the composite resin particles and molded article can be enhanced. Specifically, if the value of the inflection point is less than 0.2, the CNTs tend to agglomerate, and the dispersibility deteriorates. There is a risk that it will decrease.
The "position of the bending point" is the intersection of the approximate straight line A in the process (1) described above and the approximate straight line B in the process (3) described above.

Further, the CNT preferably has a ratio (S2/S1) of internal specific surface area S2 to total specific surface area S1 obtained from t-plot of 0.05 or more and 0.30 or less. If the value of S2/S1 of CNTs is within such a range, the dispersibility of CNTs can be enhanced, and properties such as electrical conductivity of the composite resin particles and molded article can be enhanced with a small blending amount.
Here, the total specific surface area S1 and the internal specific surface area S2 of CNT can be obtained from the t-plot. Specifically, first, the total specific surface area S1 can be obtained from the slope of the approximate straight line in process (1), and the external specific surface area S3 can be obtained from the slope of the approximate straight line in process (3). By subtracting the external specific surface area S3 from the total specific surface area S1, the internal specific surface area S2 can be calculated.

By the way, the measurement of the adsorption isotherm of CNT, the creation of the t-plot, and the calculation of the total specific surface area S1 and the internal specific surface area S2 based on the analysis of the t-plot can be performed, for example, by a commercially available measurement device "BELSORP ( (registered trademark)-mini” (manufactured by Nippon Bell Co., Ltd.).

Furthermore, CNTs preferably have a Radial Breathing Mode (RBM) peak when evaluated using Raman spectroscopy. Note that RBM does not exist in the Raman spectrum of multi-walled carbon nanotubes with three or more layers.

In addition, the CNT preferably has a ratio (G/D ratio) of G-band peak intensity to D-band peak intensity in the Raman spectrum of 0.5 or more and 5.0 or less. If the G/D ratio is 0.5 or more and 5.0 or less, it is possible to further improve the performance of the produced composite resin and molded article.

CNTs can be produced by known CNT synthesis methods such as an arc discharge method, a laser ablation method, and a chemical vapor deposition method (CVD method), without any particular limitation. Specifically, CNTs are synthesized, for example, by supplying a raw material compound and a carrier gas onto a substrate having a catalyst layer for producing carbon nanotubes on its surface, and synthesizing CNTs by chemical vapor deposition (CVD). In addition, a method of dramatically improving the catalytic activity of the catalyst layer by allowing a trace amount of oxidizing agent (catalyst activating substance) to exist in the system (super-growth method; see International Publication No. 2006/011655). , can be efficiently manufactured. In addition, below, the carbon nanotube obtained by the super growth method may be called "SGCNT."
The CNTs produced by the super-growth method may consist only of SGCNTs, or may contain other carbon components such as non-cylindrical carbon nanostructures in addition to SGCNTs.

The amount C ^CNT (% by mass) of CNTs blended in the slurry must be 0.015% by mass or more, where the total amount of the fluororesin content and the CNT content is 100% by mass. It is preferably 0.020% by mass or more, needs to be 0.200% by mass or less, and more preferably 0.100% by mass or less. When the amount of CNTs C ^CNT (% by mass) is at least the above lower limit, properties such as conductivity of the composite resin particles and molded article can be enhanced. Further, if the amount of CNTs C ^CNT (% by mass) is equal to or less than the above upper limit, it is possible to suppress the deterioration of the dispersibility of CNTs and the occurrence of unevenness in properties such as electrical conductivity of the molded product.

[Dispersion medium]
The dispersion medium is not particularly limited. For example, water, ketones such as methyl ethyl ketone (MEK), polar solvents such as alcohols such as ethanol and isopropyl alcohol, and cyclohexane, toluene, xylene, etc. Examples include non-polar solvents such as hydrocarbon solvents. One type of these solvents may be used alone, or two or more types may be used in combination at an arbitrary ratio.
Among these, from the viewpoint of improving the dispersibility of the components in the slurry, it is preferable to use at least one selected from the group consisting of cyclohexane, xylene, methyl ethyl ketone and toluene as the dispersion medium, and cyclohexane is preferably used. more preferred.

[Additive]
Additives that can be arbitrarily blended in the liquid mixture are not particularly limited, and include known additives such as dispersants.
Here, as the dispersant, a known dispersant capable of assisting the dispersion of CNTs can be used. Specifically, examples of the dispersant include surfactants, polysaccharides, π-conjugated polymers, and polymers having ethylene chains as main chains. Among them, surfactants are more preferable.

In addition, from the viewpoint of suppressing the decrease in the conductivity of the composite resin particles and the molded article, the amount of the additive compounded is preferably 1 part by mass or less per 100 parts by mass of the fluororesin described above, and is 0 mass. parts (ie the slurry does not contain additives).

[Mixing method]
The method of mixing the above-described fluororesin, CNTs, dispersion medium, and arbitrary additives to obtain slurry is not particularly limited. For example, from the viewpoint of further improving the moldability of the composite resin material by increasing the dispersibility of the fluororesin and CNTs in the slurry, the slurry is a mixture of the fluororesin, the CNTs, the dispersion medium, and any additive. After obtaining a premixed liquid, it is preferable to prepare the obtained premixed liquid by wet dispersion.

The premixed liquid can be obtained by mixing the above components under no pressure using a stirrer. The order of mixing the above components is not particularly limited, and all the components may be mixed at once, or after some components are mixed, the remaining components may be added and further mixed. good. Among them, it is preferable to mix all the components at once from the viewpoint of preparing the mixed liquid by a simple operation. Also, the ratio of each component contained in the premixed liquid is generally the same as the ratio of each component contained in the desired slurry.

The premixed liquid thus obtained is supplied to a wet disperser, and the premixed liquid is subjected to dispersion treatment to obtain a slurry. The wet disperser is not particularly limited as long as it can disperse the fluororesin and CNTs in the dispersion medium, but a wet medialess disperser is preferred.
As the wet medialess disperser, a known medialess disperser capable of performing a wet dispersing treatment without using dispersing media such as a high-speed stirrer, homogenizer and in-line mixer can be used. Among them, a homogenizer or an in-line mixer is preferable as the wet medialess disperser from the viewpoint of suppressing damage to the CNTs and dispersing the CNTs satisfactorily.

The slurry thus obtained contains the fluororesin, CNTs, dispersion medium, and optional additives. Here, when fluororesin particles are used as the fluororesin, the fluororesin in the obtained slurry may maintain the particle shape, or may have a shape other than the particle shape.

<Drying process>
In the drying step, the dispersion medium is removed from the slurry obtained in the mixing step to obtain the composite resin material. The drying method is not particularly limited, and includes a drying method using a draft chamber or the like and a drying method using a hot air drying apparatus. Drying conditions such as drying time and drying temperature can be appropriately set in accordance with conventional methods.

<Pulverization process>
In the pulverizing step, the composite resin material containing carbon nanotubes and fluororesin is pulverized. More specifically, in the pulverization step, the composite resin material is pulverized by rotating the rotor blades. The composite resin material to be subjected to the pulverization step may be obtained through the mixing step and the drying step, or may be obtained according to other methods. When pulverizing the composite resin material by rotating the rotor blades in the pulverization process, the value of D/C ^CNT , which is the value obtained by dividing the moving distance D (m) of the rotor blades by C ^CNT (% by mass), is 1,000 m. /mass% or more and 110,000m/mass% or less. Furthermore, the value of D/C ^CNT is preferably 2,500 m/mass % or more and 100,000 m/mass % or less. When the value of D/C ^CNT is equal to or higher than the above lower limit, the yield of composite resin particles can be increased by increasing uniformity. Further, when the value of D/C ^CNT is equal to or less than the above upper limit, it is possible to increase the conductivity of the obtained composite resin particles and the molded product and reduce the electrical resistance.

It should be noted that the "moving distance D (m) of the rotor blade", which is one of the determinants of the value of the parameter D / C ^CNT , is the peripheral speed (m / sec) of the stirring blade when performing the pulverization process. It can be calculated by multiplying the time (seconds). Conversely, the "travel distance D (m) of the rotor blade" value is increased by increasing the peripheral speed of the stirring blade when performing the pulverization step and/or by lengthening the pulverization time. can do. On the contrary, the value of "travel distance D (m) of the rotor blades" can be reduced by slowing the peripheral speed of the stirring blades during the pulverization process and/or by shortening the stirring time. can be done.

Then, the inventors of the present invention calculated the value of the "moving distance D (m) of the rotor blade" calculated in this way by the content ratio C ^CNT (% by mass) of the carbon nanotubes in the composite resin material to be pulverized. It was found that the parameter obtained by dividing by 2 correlates with the yield and conductivity of the composite resin particles, and the preferred range was set as described above.

The pulverizing device used when performing the pulverizing process is not particularly limited as long as it has a stirring blade. As the pulverizing device, a crushing/granulating/granulating machine capable of crushing, granulating, and granulating can be used. For example, a mill mixer, a quick mill, a wonder crusher, a Henschel mixer, etc. can be used. . The pulverization step is not particularly limited, and can be carried out under normal temperature and normal pressure conditions.

(Antistatic composition)
The antistatic composition of the present invention contains the composite resin particles obtained according to the production method of the present invention described above. Since the antistatic composition of the present invention contains the composite resin particles obtained according to the production method of the present invention, it can be suitably used to form an antistatic material having excellent conductivity and low surface resistance. . The antistatic composition may contain optional additives.

The manufacturing method of the antistatic composition is not particularly limited. For example, the antistatic composition can be produced by mixing the composite resin particles obtained according to the production method of the present invention and any of the additives described above according to a standard method.

(Molded body)
The molded article of the present invention is obtained by molding the composite resin particles obtained according to the production method of the present invention described above. Since the molded article of the present invention contains the composite resin particles obtained according to the production method of the present invention, it has excellent conductivity and low surface resistance.

The molded article of the present invention can be obtained by molding the composite resin particles obtained according to the above-described manufacturing method of the present invention according to a known method suitable for the application. The method for producing the molded article of the present invention is not particularly limited, and a known molding method such as compression molding can be used. Moreover, a molded body obtained by molding the composite resin material may optionally be subjected to a baking treatment.

The present invention will be specifically described below based on examples, but the present invention is not limited to these examples. In Examples and Comparative Examples, various measurements and evaluations were carried out as follows.

<Calculation of moving distance D (m) of rotor blade>
It was calculated according to moving distance D (m)=peripheral speed V (m/sec) of rotor blade×time (sec). The peripheral speed V (m/sec) of the rotor is expressed by V=πφN/1000, where φ (mm) is the diameter of the stirring blade and N (rpm) is the rotation speed.

<Surface resistivity>
A mold at room temperature was filled with the composite resin particles produced in Examples and Comparative Examples, and a preform (130 mm×80 mm, thickness 2 mm) was obtained under a preforming pressure of 9 MPa and a pressure holding time of 5 minutes. After the preform was removed from the mold, it was fired in a free state in a hot air circulating furnace at 370° C. for 6 hours. After polishing the surface of the molded product after firing with waterproof abrasive paper (No. 3000), low resistance is measured with a resistivity meter Loresta (manufactured by Mitsubishi Chemical Analytech, product name: "MCP-T610", probe LSP), and high resistance is The surface resistivity (Ω/sq.) of the composite resin material was measured using a resistivity meter Hiresta (manufactured by Mitsubishi Chemical Analytic Tech, product name “MCP-HT800”, probe URSS).

<Calculation of yield>
In the examples and comparative examples, the mass M1 of the composite resin material before pulverization obtained through the drying process was measured. After that, the mass M2 of the composite resin particles classified by passing through a mesh with a wire diameter of 1.4 mm after the pulverization process was measured. The yield was then calculated according to Yield (%) = M2/M1 x 100. The yield calculated in this way is preferably 75% or more.

(Example 1)
<Mixing process>
In a 5 L SUS can, 2720 g of cyclohexane as a dispersion medium, 679.32 g of fluororesin particles (manufactured by AGC, product name “Fluon PTFE G163”, average particle size 30 μm, specific gravity 2.15), and single-walled carbon nanotubes (Nippon Zeon Co., Ltd., product name “ZEONANO SG101”, specific gravity 1.7, carbon purity: 99.5%, average diameter 3.5 nm, 3σ/Av: 0.60, average length: 450 μm, BET specific surface area: 1325 m ² /g; t-plot: upwardly convex) was mixed with 0.68 g (the amount of carbon nanotubes added to the fluororesin was 0.100% by mass), and an in-line mixer, Cavitron (manufactured by Pacific Machinery Co., Ltd., Using a product name “CD1000”, rotor/stator: slit type, minimum clearance 0.25 mm), dispersion treatment is performed for 30 minutes at a temperature of 20 ° C. and a rotation speed of 6000 rpm (peripheral speed: 13 m / sec). and a slurry-like dispersion containing carbon nanotubes.
<Drying process>
Next, the slurry is dried with a draft using a fluorine-coated aluminum vat (AS ONE part number: 2-339-07, model number: Fuka No. 1) to remove the dispersion medium, and then placed in a hot air dryer (manufactured by Espec). A composite resin material containing a fluororesin and a single-walled carbon nanotube was obtained by drying with hot air at 125° C. for 2 hours.
<Pulverization process>
The composite resin material obtained through the drying step was pulverized using a mill mixer, which is a pulverizer equipped with stirring blades, to obtain composite resin particles. The peripheral speed of the stirring blades in the pulverization process was calculated from a stirring blade (rotating body) diameter of 42 mm and a rotation speed of 20000 rpm, and the moving distance of the rotary blades was calculated over a pulverization time of 6 seconds.
After putting the obtained composite resin particles into a mold, using a compression molding machine (manufactured by Dumbbell Co., model number "SDOP-1032IV-2HC-AT"), under the conditions of normal temperature, pressure of 9 MPa, pressure holding time of 5 minutes. Preforming was performed to obtain a sheet-like preform having a width of 130 mm×80 mm and a thickness of 2 mm. After the preform was released from the mold, it was fired in a free state in a hot air circulating furnace at 370° C. for 6 hours to obtain a formed body. Surface resistivity and yield were evaluated for the obtained molded body. Table 1 shows the results.

(Example 2)
Various operations, Measurements and evaluations were performed. Table 1 shows the results.

(Example 3)
In the mixing step, the amount of fluororesin was changed to 679.66 g, and the amount of CNT added was changed to 0.34 g (the amount of CNT added to the fluororesin was 0.050% by mass). In addition, a quick mill (“QMY-30” manufactured by Seishin Enterprise Co., Ltd.) was used as a pulverizer having stirring blades in the pulverization step. The peripheral speed of the stirring blades of the quick mill was calculated from a stirring blade (rotating body) diameter of 180 mm and a rotation speed of 900 rpm, and the moving distance of the rotating blades was calculated over a grinding time of 30 seconds. Various operations, measurements, and evaluations were performed in the same manner as in Example 1 except for these points. Table 1 shows the results.

(Example 4)
Various operations and measurements were performed in the same manner as in Example 1, except that 679.73 g of fluororesin and 0.27 g of CNTs were added in the mixing step (the amount of CNTs added to the fluororesin was 0.040% by mass). , and evaluated. Table 1 shows the results.

(Example 5)
Various operations and measurements were performed in the same manner as in Example 1, except that 679.83 g of fluororesin and 0.17 g of CNTs were added in the mixing step (the amount of CNTs added to the fluororesin was 0.025% by mass). , and evaluated. Table 1 shows the results.

(Example 6)
In the pulverization step, a Wonder Crusher (manufactured by Osaka Chemical Co., Ltd., "WC-3L") was used as a pulverizer having stirring blades. During the pulverization, cold water at room temperature was flowed to exchange heat, thereby suppressing temperature rise. The peripheral speed of the stirring blade was calculated from a stirring blade (rotating body) diameter of 100 mm and a rotational speed of 9700 rpm, and the moving distance of the rotating blade was calculated over a pulverization time of 60 seconds. Various operations, measurements, and evaluations were performed in the same manner as in Example 1 except for these points. Table 1 shows the results.

(Example 7)
A molded body was produced in the same manner as in Example 6, except that 679.66 g of fluororesin and 0.34 g of CNTs were added in the mixing step (the amount of CNTs added to the fluororesin was 0.050% by mass). . Various operations, measurements, and evaluations were performed in the same manner as in Example 1 except for these points. Table 1 shows the results.

(Example 8)
A molded body was produced in the same manner as in Example 6, except that 679.73 g of fluororesin and 0.27 g of CNTs were added in the mixing step (the amount of CNTs added to the fluororesin was 0.040% by mass). . Various operations, measurements, and evaluations were performed in the same manner as in Example 1 except for these points. Table 1 shows the results.

(Example 9)
In the mixing step, 679.66 g of fluororesin and 0.34 g of CNT were added (the amount of CNT added to the fluororesin was 0.050% by mass). In the pulverization step, an FM mixer (manufactured by Nippon Coke Co., Ltd., "FM10"), which is a Henschel mixer, was used as a pulverizer having stirring blades. During the pulverization, cold water at room temperature was flowed to exchange heat, thereby suppressing temperature rise. The peripheral speed of the stirring blade was 1000 m/min, and the moving distance of the rotary blade was calculated by multiplying the pulverization time by 5 minutes. Various operations, measurements, and evaluations were performed in the same manner as in Example 1 except for these points. Table 1 shows the results.

(Comparative example 1)
Various operations and measurements were performed in the same manner as in Example 1, except that 679.93 g of fluororesin and 0.07 g of CNTs were added in the mixing step (the amount of CNTs added to the fluororesin was 0.010% by mass). , and evaluated. Table 1 shows the results.

(Comparative example 2)
A molded body was produced in the same manner as in Example 6, except that 679.83 g of fluororesin and 0.17 g of CNTs were added in the mixing step (the amount of CNTs added to the fluororesin was 0.025% by mass). . Various operations, measurements, and evaluations were performed in the same manner as in Example 1 except for these points. Table 1 shows the results.

(Comparative Example 3)
In the pulverization step, a Wonder Crusher (manufactured by Osaka Chemical Co., Ltd., "WC-3L") was used as a pulverizer having stirring blades. During the pulverization, cold water at room temperature was flowed to exchange heat, thereby suppressing temperature rise. The peripheral speed of the stirring blade was calculated from a stirring blade (rotating body) diameter of 100 mm and a rotational speed of 9700 rpm, and the movement distance of the rotating blade was calculated over a pulverization time of 300 seconds. Various operations, measurements, and evaluations were performed in the same manner as in Example 1 except for these points. Table 1 shows the results.

(Comparative Example 4)
Various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that the pulverization time was set to 1 second in the pulverization step. Table 1 shows the results.

From Table 1, the CNT content ratio in the composite resin material to be pulverized is set to a predetermined range (CNT content ratio C ^CNT is 0.015% by mass or more and 0.200% by mass or less), and in the pulverization process, the rotor blade When the composite resin material is pulverized by the rotation of the rotor, the value of D/C ^CNT , which is the value obtained by dividing the moving distance D (m) of the rotor blade by C ^CNT (mass%), is 1,000 m/mass% or more 110 ,000 m/mass % or less, composite resin particles capable of forming compacts with low electrical resistance could be produced at a high yield.
On the other hand, in Comparative Example 1 in which the CNT content ratio C ^CNT is less than 0.015% by mass, the value of D/C ^CNT is outside the predetermined range (1,000 m/mass% or more and 110,000 m/mass% or less). In Comparative Examples 2 to 4, the electrical resistance of the obtained molded articles was high, or the yield of the composite resin particles was not sufficient.

Claims

A method for producing composite resin particles, comprising a pulverizing step of pulverizing a composite resin material containing carbon nanotubes and fluororesin,
In the composite resin material, the carbon nanotube content C CNT (% by mass) is 0.015% by mass or more and 0.200% by mass or less.
In the pulverization step, when the composite resin material is pulverized by rotating the rotor blades, the value obtained by dividing the moving distance D (m) of the rotor blades by the C CNT (% by mass) is D/movement of rotor blades. A method for producing composite resin particles, wherein the value of the distance D is 1,000 m/mass % or more and 110,000 m/mass % or less.
The method for producing composite resin particles according to claim 1, wherein the carbon nanotube has a carbon purity of 98.0% or more.
The method for producing composite resin particles according to claim 1, wherein the carbon nanotubes include single-walled carbon nanotubes.
An antistatic composition comprising composite resin particles produced by the method for producing composite resin particles according to any one of claims 1 to 3.
A molded body obtained by molding composite resin particles produced by the method for producing composite resin particles according to any one of claims 1 to 3.