JP4399525B2 - Method for producing carbon nanowire-dispersed resin composition - Google Patents

Description

  The present invention relates to a method for producing a carbon nanowire-dispersed resin composition that is conductive, and that can obtain a lightweight, high-strength resin molded product.

  Carbon nanowires called carbon nanotubes (also called carbon fibrils) or carbon nanofibers can be obtained by dispersing and mixing in a small amount in a matrix resin rather than carbon black or the like to obtain a resin composition with conductivity ( (See Patent Document 1). Accordingly, when a transparent matrix resin is used, a transparent resin film having excellent conductivity can be obtained.

However, the carbon nanostriate is expensive and generally has a large number of fibers in a state of being twisted. Therefore, when the carbon nanostriate is dispersed and mixed in the matrix resin, it is dispersed in a state of being twisted. Therefore, the necessary conductivity cannot be ensured unless the carbon nano-striate more than the theoretical amount is added, and there is a problem in terms of manufacturing cost.
On the other hand, if a high shear force is applied to the mixture for a long time during dispersion mixing in order to eliminate wrinkling, the matrix resin may be burned or deteriorated due to frictional heat or the like, and the intended strength and transparency may not be ensured.

Therefore, in the carbon nano-striate, the carbon nano-striate is made to loosen the carbon nano-striate in a polar solution by treating the carbon nano-striate with a strong acid containing sulfur and an oxidizing agent. Has already been proposed (see Patent Document 2).
However, in the above dispersion method, the strong acid used may have an adverse effect on the matrix resin and the like, so it must be washed thoroughly after dispersion, and workability is poor. Moreover, since it is made to disperse | distribute to a polar solvent after processing with a strong acid, there exists a problem that the use to the system which does not use a polar solvent is impossible.

JP-T 8-508534 Special Table 2000-511245

  In view of the circumstances as described above, the present invention disperses and mixes the carbon nano-striates in the matrix resin with good workability, while preventing the carbon nano-striates from being melted and causing deterioration. An object of the present invention is to provide a method for producing a carbon nanowire-dispersed resin composition that can be used.

  In order to achieve the above object, the method for producing a carbon nanowire-dispersed resin composition according to claim 1 of the present invention (hereinafter referred to as `` the production method of claim 1 '') is characterized in that In the method for producing a carbon nano-striate-dispersed resin composition in which a striate is dispersed and mixed, the method includes a step of melt-kneading a matrix resin and a carbon nano-striate in the presence of a resin plasticizing gas. .

  In the present invention, examples of the resin plasticizing gas include carbon dioxide gas, nitrogen gas, butane gas, pentane gas and the like, and carbon dioxide gas is preferably used as in claim 2. Since the carbon nanostriate can be dispersed and mixed in the matrix resin with good workability while loosening the carbon nanostriate, use in a subcritical state or a supercritical fluid state is preferable.

  In the present invention, the carbon nanowire is not particularly limited as long as it has a diameter of 300 nm or less. Single-walled carbon nanotubes (for example, SWCNT manufactured by Hyperion), multi-walled carbon nanotubes (for example, MWCNT manufactured by Hyperion), vapor-grown carbon nanofibers (for example, VGCF manufactured by Showa Denko), etc. Vapor growth carbon nanofibers are preferably used.

The matrix resin used in the present invention is not particularly limited, and any of a thermoplastic resin and a thermosetting resin can be used.
Examples of the thermoplastic resin include general-purpose thermoplastic resins, engineering plastics, and difficult-to-mold resins.
Examples of the general-purpose thermoplastic resin include polyolefin resins, vinyl resins such as vinyl chloride and vinyl acetate, and styrene resins.

Examples of the engineering plastics include polycarbonate, polyamide, polyethylene terephthalate, polybutylene terephthalate, acrylic resin, polyacetal resin, and polyvinyl acetal resin.
Furthermore, although it is thermoplastic, the molding temperature is high, it is difficult to lower the fluidity even if the temperature is raised to the upper limit temperature of ordinary kneading extrusion equipment, or the thermoforming temperature and the thermal decomposition temperature are close, causing decomposition during molding. It is easy, and because temperature, back pressure, etc. require high altitude, it is difficult to knead and mold due to motor capacity and heater performance with normal equipment, or management of temperature, pressure, etc. requires extremely delicate control. Even in the case of a resin such as carbon nanowires, carbon nanowires can be dispersed due to the easy molding effect of the resin plasticizing gas.

  Examples of the thermoplastic resin that is difficult to mold include ultra high molecular weight PE resin, fluororesin, aromatic polyamide, polyamideimide, polyetheretherketone, polyimide, and biodegradable polymer.

  The biodegradable polymers include microbial biopolyesters (PHB / V, etc.), bacterial cellulose, microbial polysaccharides (pullulan, curdlan, etc.), chemically synthesized aliphatic polyesters (polycaprolactone, polybutylene succinate, polyethylene succinate). Nate, polyglycolic acid, polylactic acid, polyhydroxybutyrate, polyhydroxybutyrate valerate, etc.), polyvinyl alcohol, polyamino acids (PMGL, etc.), polyurethane, nylon oligomer and the like.

  Furthermore, examples of the biodegradable polymer include natural products such as chitosan / cellulose, starch, and cellulose acetate, starch / aliphatic polyester that is a composite, starch / polyvinyl alcohol, the above mixtures, and laminates. In addition, although the said classification | category is a classification | category by the main body of a manufacturing method, it may be manufactured by various manufacturing methods by the environmental property, ease of manufacture, etc. like the example of polylactic acid.

  Next, the thermosetting resin can be kneaded and molded at a lower temperature than usual due to the plasticizing effect of the resin plasticizing gas. It can be controlled to such an extent that it does not solidify in the apparatus. Examples of the thermosetting resin include a thermosetting polyester resin, an epoxy resin, and a phenol resin.

  In order to increase conductivity, carbon black, metal fine particles, and other commonly used additives other than carbon nano-striates may be mixed for other purposes by a usual method such as master batch or direct mixing.

  According to the method for producing a carbon nano-striated dispersion resin composition of the present invention, the carbon nano-striates can be dispersed and mixed in the matrix resin with good workability while loosening the carbon nano-striates. However, since the striate does not protrude from the surface of the molded product and does not break because it is thin and flexible, there is little dropout of the conductive striated piece from the surface of the molded product. For this reason, it is difficult to cause a short circuit of the conductive circuit, and since there is less outgas, containers such as electronic component trays that require antistatic properties, housings, EMI shielding materials, electrostatic paints that require high conductivity, By being filled at a high concentration, it can be suitably used for conductive wiring materials and the like, sheets for heat dissipation materials of CPUs that require thermal conductivity, and heat dissipation molded parts. Also, since the carbon nanowires are thin and difficult to break, they have excellent repetitive recyclability, and since surface friction resistance is reduced for recycling applications, they have excellent surface smoothness for applications that require low friction materials, etc. It is suitably used for applications requiring smoothness.

Since the method for producing a carbon nano-striated body dispersed resin composition according to the present invention is configured as described above, the carbon nano-striated body is uniformly dispersed while eliminating the wrinkles, and even with a small amount of addition. A carbon nano-striate resin composition having high conductivity is obtained.
Further, if carbon dioxide gas is used as the resin plasticizing gas as in claim 2, it is nonflammable gas and high safety, and plasticization easily occurs at a relatively low temperature and low pressure. Even if released into the atmosphere, it has little adverse effect on the environment and is safe.

Hereinafter, the present invention will be described in detail with reference to the drawings showing embodiments thereof. Figure 1 represents one embodiment of the manufacturing method of the engagement Ru carbon nano striatum dispersion resin composition of the present invention.

  As shown in FIG. 1, in this manufacturing method, first, polycarbonate pellets as a matrix resin are supplied from the first raw material supply conduit 11a to the hopper body 11 of the hopper 1, and the carbon nano filaments are supplied from the second raw material supply conduit 11b. Commercially available carbon nanotube dispersion pellets in which carbon nanotubes as a body are previously dispersed by a known method are respectively supplied and stirred and mixed by the agitator 12 in the hopper main body 11, and the resulting mixture is passed through the hopper conduit 13. 2 is supplied into the extruder 2 through a supply port 21 of a two-screw type twin-screw extruder (hereinafter referred to as “extruder” only) 2 and melt-kneaded in the extruder 2 as shown in FIG.

  Further, carbon dioxide gas as a resin plasticizing gas is supplied from a gas supply port 22 provided at a position where the molten resin downstream from the supply port 21 is filled, and the temperature and pressure are set to a supercritical state of carbon dioxide gas. After further melt-kneading, the carbon dioxide dissolved in the resin is discharged from the gas outlet 23 to the outside of the cylinder 25, and then continuously from the pelleting die 3 provided at the tip of the extruder 2 as a strand 4a. Extruded and air cooled while receiving from below by the belt conveyor 5. And the cooled strand 4a is cut | disconnected shortly with the pelletizer 6, and the pellet 4b as the carbon nanotube dispersion | distribution resin composition of this invention is obtained.

  In FIG. 1, reference numeral 24 denotes a screw, and 26 denotes a heater unit. The heater unit 26 includes a water cooling coil for water cooling in combination with an electric resistance heater for heating, although not shown. The control unit controls the material flowing in the heater unit 26 and the cylinder 25 so as to have an appropriate temperature.

According to this manufacturing method, when the polycarbonate as the matrix resin and the carbon nanotubes are melt-kneaded in the extruder 2, carbon dioxide gas is supplied to lower the viscosity of the polycarbonate. The polycarbonate and the carbon nanotubes can be easily stirred while suppressing the heat generation. Moreover, due to the high dispersibility of the carbon dioxide gas, which is a supercritical fluid, the carbon nanotubes are dispersed in the polycarbonate in a state where the carbon nanotubes are eliminated from the nano-base.
Therefore, the required conductivity can be ensured by adding a small amount of carbon nanotubes compared to the conventional one, a film having a conductive layer at a low cost, an endless belt having excellent strength and conductivity, etc. Can be obtained.

  In addition, since carbon dioxide gas is used as the resin plasticizing gas, even if the exhausted carbon dioxide gas leaks into the atmosphere, there is almost no adverse effect on the environment, and there is no fear of ignition etc., which is safe. .

The present invention is not limited to the above embodiment. For example, in the above embodiment, the extruder is a double-screw type twin-screw extruder, but it may be a single-screw extruder or a multi-screw extruder such as a three-screw extruder. Articles and other types may be used.
In the above embodiment, pellets in which carbon nanotubes are dispersed in advance by a known method are supplied to the extruder as raw materials. However, the carbon nanowires and the matrix resin may be directly mixed. Alternatively, the carbon nanowires may be preliminarily dispersed in a resin plasticizing gas atmosphere, supplied to the matrix resin filling region of the extruder together with the resin plasticizing gas, and stirred and mixed with the matrix resin. Absent.

In the above embodiment, after the carbon dioxide gas supplied into the extruder 2 is discharged from the gas discharge port 23 provided at the end portion of the extruder 2, the melt-kneaded material is extruded from the pelleting die 3. However, the carbon dioxide gas may be gradually evaporated from the matrix resin after the melt-kneaded product is extruded from the die.
In the above embodiment, the pellets 4b are obtained by extruding the pellets 4b using the pelleting die 3, but a desired molded product is obtained directly using a T die, a round die, a modified die or the like. It doesn't matter.
Hereinafter, specific examples of the present invention will be described.

  Polycarbonate (Mitsubishi Engineering Co., Ltd. Iupilon PC (S2000)) and ready-made master batch containing carbon nanotubes (Hyperion Co., Ltd. Hyperion PC Masterbatch (85% by weight low molecular polycarbonate) so that the final carbon nanotube content is 1% by weight. %, Carbon nanostriates (d = 10 nm, L = 1 to 10 μm) 15 wt%)) with a stirrer at a ratio of 14.15: 1, and this mixture is mixed with each length as shown in FIG. C1 of the same direction rotating twin screw extruder (BT-40-S2-42-L manufactured by Plastics Engineering Laboratory Co., Ltd.) 2 having seven cylinder units C1 to C7 having a length of 20 cm, a head H, and a die D Is fed at an extrusion rate of 5 kg / hr from the supply port provided in the extruder, and the extruder at a screw speed of 300 rpm. With melt-kneaded at an internal, it was supplied such that the concentration of 1% carbon dioxide from the C3 portion of the resin in the extruder 2 is filled. Then, after carbon dioxide gas is sucked and exhausted from the C7 portion, the header H and the die D are continuously extruded, and the belt conveyor 5 and the pelletizer 6 are passed through the belt conveyor 5 and the pelletizer 6 as shown in FIG. A resin composition pellet of 0 mm was obtained.

A square plate-shaped molded product of 30 mm × 30 mm × 2 mm was injection-molded using the obtained pellets as a raw material under the following injection conditions.
[Injection conditions]
・ Injection speed: 20 mm ³ / s
-Holding pressure: 30 MPa
・ Pressure holding time: 3s
・ Cooling time: 20s

  A plate-like molded product was obtained in the same manner as in Example 1 except that the concentration of carbon dioxide gas was 5%.

  Polycarbonate (Iupilon PC (S2000) manufactured by Mitsubishi Engineering) and a masterbatch containing pre-made carbon nanotubes (Hyperion PC masterbatch (Hyperion PC 85% by weight)) so that the final carbon nanotube content is 5% by weight. %, Carbon nanotubes (d = 10 nm, L = 1 to 10 μm) 15 wt%)) in the same manner as in Example 1 except that a mixture of 2.15: 1 was mixed with a stirrer. A molded product was obtained.

(Comparative Example 1)
A plate-shaped molded article was obtained in the same manner as in Example 1 except that carbon dioxide gas was not supplied into the extruder 2.

(Comparative Example 2)
A plate-like molded product was obtained in the same manner as in Example 3 except that carbon dioxide gas was not supplied into the extruder 2.

  The volume resistivity (unit: Ω · cm) of the plate-like molded products obtained in Examples 1 to 3 and Comparative Examples 1 and 2 was examined, and the results were obtained as the temperature of each part of the extruder during pellet production, and the screw drive motor. Table 1 shows the driving current values. The volume resistivity was calculated from the resistance value (average value of n number 5) after 5 minutes from the start of voltage application at an applied voltage of 100V.

If kneading of the matrix resin and the carbon nanotubes from Table 1 is performed in the presence of carbon dioxide gas, which is a resin plasticizing gas, the viscosity of the resin is lowered, and the carbon nanotubes are uniformly dispersed while eliminating the dripping, it can be seen that the resin composition having a high electrical conductivity even in a small amount of addition can be obtained.

According to the method for producing a carbon nanowire-dispersed resin composition of the present invention, a resin composition having high conductivity can be obtained even when a small amount of carbon nanostriates is added. Therefore, it can be suitably used for production of an intermediate material.

It is a figure which shows typically one example of the apparatus used for the manufacturing method of the carbon nanotube dispersion | distribution resin composition concerning this invention. It is an extruder sectional drawing of the apparatus of FIG. It is explanatory drawing explaining the extruder used in the Example.

Explanation of symbols

4b Pellets (carbon nano-striate dispersion resin composition)

Claims (2)

  In the method for producing a carbon nano-striated dispersion resin composition in which carbon nano-striates are dispersed and mixed in a matrix resin, the method includes melt-kneading the matrix resin and the carbon nano-striates in the presence of a resin plasticizing gas. A method for producing a carbon nanowire-dispersed resin composition, comprising: The method for producing a carbon nanowire-dispersed resin composition according to claim 1, wherein the resin plasticizing gas is carbon dioxide.

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