JP2006016450A - Manufacturing method of carbon nanofilament-dispersed resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a carbon nanofilament-dispersed resin composition which permits uniform dispersion without strong power on dispersing the carbon nanofilament in a matrix resin. <P>SOLUTION: The manufacturing method of the carbon nanofilament-dispersed resin composition comprises dispersing and mixing the carbon nanofilament in the matrix resin, where the manufacturing method comprises a step for kneading the matrix resin with the carbon nanofilament in the presence of an aliphatic alcohol. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a carbon nano-striated dispersion resin composition in which carbon nano-striates are uniformly dispersed in a matrix resin. Furthermore, the present invention relates to powder carbon nano-particles in a matrix resin by a kneader such as an extruder. The present invention relates to a method for producing a carbon nano-striated dispersion resin composition in which striated powder is dispersed.

  Carbon nanowires, also called carbon nanotubes (also called carbon fibrils) or carbon nanofibers, can be obtained by simply dispersing and mixing in a matrix resin in a smaller amount than carbon black and the like, thereby obtaining 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, carbon nanostriates are very thin and generally exist as powders with a large number of fibers twisted. The process has the following problems in a master batch process in which carbon nanowires are dispersed and mixed in a matrix resin. That is, for example, when resin and powdered carbon nanowires are directly fed into an extruder little by little with an auto feeder, uniform dispersion is difficult and a large amount of power is required to rotate the screw.

  On the other hand, if a high shear force is applied to the mixture for a long time during dispersion mixing for uniform dispersion, the matrix resin may be burned or altered due to frictional heat, etc., and the intended strength and transparency may not be ensured. is there.

  Furthermore, since the carbon nanostriate is expensive and generally exists in a state where a large number of fibers are twisted, the carbon nanostriate is dispersed in a whirled state when being dispersed and mixed in the matrix resin. Therefore, the required conductivity cannot be ensured unless carbon nanostriates exceeding the theoretical amount are added, and there is a problem in terms of manufacturing cost.

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 adversely affect 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 provides a method for producing a carbon nanowire-dispersed resin composition that can be uniformly dispersed without using a large power in dispersing the carbon nanowire into a matrix resin. The purpose is to provide.

  In order to achieve the above object, a method for producing a carbon nano-striated dispersion resin composition according to claim 1 of the present invention is a carbon nano-striated dispersion resin in which carbon nano-striates are dispersed and mixed in a matrix resin. The method for producing the composition is characterized by comprising a step of kneading the matrix resin and the carbon nanowires in the presence of an aliphatic alcohol.

  The method for producing a carbon nano-striated dispersion resin composition according to claim 2 is a method for producing a carbon nano-striated dispersion resin composition in which carbon nano-striates are dispersed and mixed in a matrix resin. It is characterized by comprising a step of kneading the nanostriatum and the aliphatic alcohol in the presence of a resin plasticizing gas.

  The method for producing a carbon nanowire-dispersed resin composition according to claim 3, wherein the aliphatic alcohol is a saturated or unsaturated aliphatic alcohol having 12 to 22 carbon atoms. It is a manufacturing method of the carbon nano linear body dispersion | distribution resin composition of description.

  The method for producing a carbon nano-striated dispersion resin composition according to claim 4, wherein the resin plasticizing gas is carbon dioxide gas. It is a manufacturing method of a thing.

This will be described in detail below.
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, but the thermoplastic resin is preferable because it is easy to mold and has excellent recyclability. .
The thermoplastic resin used in the present invention is not particularly limited, and examples thereof 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 to use, and the temperature, back pressure, etc. require a high degree, so it is difficult to knead and mold with normal equipment due to the kneading motor capacity and heater performance, or the management of temperature and pressure requires extremely delicate control. Even in the case of resins such as, and the like, the carbon nano-striates can be dispersed due to the effect of facilitating molding by adding a resin plasticizing gas to the aliphatic alcohol.

  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 environmentality, ease of manufacture, etc. like the example of polylactic acid.

  Next, the thermosetting resin only needs to have fluidity before curing, and even if it is a resin that has low fluidity at molding temperature and is difficult to knead, Because of the plasticizing effect of the resin plasticizing gas, kneading and molding can be performed at a temperature much lower than usual, so that it does not cure during kneading molding or is controlled so that it does not solidify in the apparatus even if a slight curing reaction occurs. If you can, you can use it. Examples of the thermosetting resin include a thermosetting polyester resin, an epoxy resin, and a phenol resin.

  The carbon nanowires in the present invention include so-called carbon nanotubes, but are not particularly limited as long as the diameter is 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 suitable for general purpose applications because they are inexpensive. For highly transparent conductive applications, single-walled thin carbon nanotubes are preferable because they are transparent and have high conductivity.

In the present invention, the alcohol of the aliphatic alcohol refers to a compound having a hydroxyl group bonded to a saturated sp ³ hybrid carbon. What has the effect | action which wets the carbon nanostriate which is the function which should be expected originally, and loosens a carbon nanostriate, and the thing excellent in compatibility with matrix resin are preferable. In the case of kneading with an extruder, a molding temperature of 150 to 350 ° C. is preferable, so that it is liquid in this temperature range, and in terms of safety, the melting point is higher than normal temperature and the vapor pressure is low. The valence is not limited and may be multivalent. The carbon chain may be saturated or unsaturated, but an aliphatic alcohol is preferred. The carbon number of the carbon chain in the aliphatic alcohol is 9 or more and 30 or less, more preferably 12 or more and 22 or less. Among them, stearyl alcohol is effective and preferable in terms of cost.

  The kneading in the present invention means that the matrix resin is brought into a fluid state by heating or the like, and carbon nanowires are added and mechanical shear stress such as stirring is applied and dispersed. As an apparatus for kneading, an ordinary apparatus can be used. When a thermoplastic resin is used as the matrix resin, a melt kneading method is used in which the thermoplastic resin is melted and kneaded. As an apparatus for melt kneading, an ordinary apparatus can be used, but it is preferable because the extruder can be used consistently until molding, and may be uniaxial or biaxial, but from the viewpoint of kneading effect, a biaxial extruder is preferred. In the twin screw extruder, the same direction twin screw extruder is more preferable.

In the present invention, carbon nanostriates can be fed into a kneading machine such as an extruder as a powder or in a master batch, but when powdered carbon nanostriates are fed directly This is particularly effective.

  In the kneading machine, the matrix resin and the carbon nanowires are mixed and dispersed with a low torque in the presence of the aliphatic alcohol in a short time. If the obtained carbon nano-striated dispersion resin composition is an extruder, it is extruded from a die attached as it is, extruded as it is, and then molded by a film, a sheet, or a further connected injection molding machine, etc. Alternatively, it may be formed into a pellet as a master batch and then formed separately.

  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. Various additives such as a dispersant such as calcium stearate may be used to improve the moldability.

In the present invention, it is preferable to knead the matrix resin, the carbon nanowires, and the aliphatic alcohol in the presence of a resin plasticizing gas.
By kneading in the presence of the resin plasticizing gas, the degree of dispersion of the carbon nanostriates is further increased, and when the carbon nanostriates existing in a state where a large number of fibers are twisted are dispersed and mixed in the matrix resin, Since it can disperse | distribute so that the state of the carbon nano-striate of a state may be loosened, a big effect can be brought out by addition of a small amount of carbon nano-striate.

  In the present invention, examples of the resin plasticizing gas include carbon dioxide gas, nitrogen gas, butane gas, and pentane gas. Among these, carbon dioxide gas is preferably used. It is more preferable to use the resin plasticizing gas in a subcritical state or a supercritical state because the carbon nanostriate can be dispersed and mixed in the matrix resin with good workability while loosening the carbon nanostriate.

According to the method for producing a carbon nanowire-dispersed resin composition according to the present invention, the carbon nanowire can be directly charged into the matrix resin, and can be quickly applied to the matrix resin without requiring large power. Productivity is good because the carbon nanowires can be uniformly dispersed and mixed.
Since the carbon nano-striate-dispersed resin composition according to the present invention is uniformly dispersed, the carbon nano-striate-dispersed resin composition has high conductivity even when added in a small amount and has little deterioration of the matrix resin.

  In addition, if a resin plasticizing gas is used, the carbon nanowires are more highly dispersed in the matrix resin.

  If carbon dioxide is used as the resin plasticizing gas, it is nonflammable and highly safe. Plasticization is easy to occur at relatively low temperatures and low pressures. Even if the plasticizing gas is released into the atmosphere, it will have a negative impact on the environment. There is nothing.

  The molded article using the carbon nano-striated dispersion resin composition obtained by using this production method is a molded article because the carbon nano-striated body is thin and flexible, so that the linear body does not protrude from the surface of the molded product and does not break. Less loss of conductive filaments from the surface. 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. In addition, since carbon nanowires are thin and difficult to break, they are excellent in repetitive recyclability, so that surface friction resistance is reduced, and surface friction resistance is reduced. Therefore, it is suitably used for applications requiring smoothness.

  Hereinafter, the present invention will be described in detail with reference to the drawings showing embodiments thereof. FIG. 1 shows one embodiment of a method for producing a carbon nanowire-dispersed resin composition according to the present invention.

As shown in FIG. 1, in this manufacturing method, first, a pellet obtained by mixing polycarbonate pellets as a matrix resin, stearyl alcohol powder and calcium stearate powder with a Henschel mixer is put into a hopper 1, and a weight type feeder is used. 11, the mixture is dropped into the hopper 3 by a fixed amount. On the other hand, vapor-grown carbon nanofiber powder as carbon nanostriates is put into the hopper 2, and is dropped into the hopper 3 by the weight type feeder 21 in a fixed amount.
The raw material is supplied into the extruder 4 from a supply port 41 of a twin-screw extruder (hereinafter referred to as “extruder” only) 4 and melt-kneaded in the extruder 4.

  After kneading in the extruder 4, it is continuously extruded as a strand 5 a from a pelleting die D provided at the tip of the extruder 4, and air-cooled while being received from below by a belt conveyor 6. And the cooled strand 5a is cut | disconnected shortly with the pelletizer 7, The pellet 5b as the carbon nanotube dispersion | distribution resin composition of this invention is obtained.

  In FIG. 1, reference numeral 44 denotes a screw, and a heater unit (not shown) is provided around the cylinder of the extruder. Further, a water cooling coil (not shown) for water cooling is combined with an electric resistance heater for heating. ), And a control device (not shown) is controlled so that the heater unit itself and the material flowing in the cylinder have an appropriate temperature. The screw 44 is connected to a main motor (not shown) via a speed reducer (not shown), and measures the current flowing through the main motor.

Further, for the case of using the resin plasticizing gas, the extruder 4 is provided with a resin plasticizing gas supply source (not shown) such as a cylinder at a position where the molten resin downstream from the raw material supply port 41 is filled. ) Is provided with a gas injection port 42 for supplying the gas guided by the supply pipe to the extruder, and the resin plasticizing gas is injected to bring the temperature and pressure to the supercritical state of the resin plasticizing gas, followed by further melt-kneading. After that, a gas discharge port 43 for discharging the carbon dioxide gas outside the cylinder is provided. The resin plasticizing gas pressure is measured with a strain gauge pressure gauge attached to the cylinder.
When the resin plasticizing gas is not used, the gas inlet 42 is closed and the gas outlet 43 is used in an open state in order to remove decomposition gas and the like.

According to the production method using the resin plasticizing gas, when the polycarbonate as the matrix resin and the carbon nanotube are melt-kneaded in the extruder 2, not only the kneading by adding stearyl alcohol is facilitated, but also the resin plasticizing Since the gas is supplied to lower the viscosity of the polycarbonate, the polycarbonate and the carbon nanotube can be easily stirred and mixed while suppressing the heat generation of the resin due to the frictional resistance. In addition, due to the high dispersibility of the plasticizing gas in the supercritical or subcritical state, 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 secured by adding a small amount of carbon nanotubes compared to the conventional one, and the molded product such as a conductive film or an endless belt having excellent strength and conductivity can be obtained at low cost. Can be obtained.

  Further, when carbon dioxide is used as the resin plasticizing gas, it is safe because it can be brought into a supercritical or subcritical state at a relatively low pressure and low temperature and there is no fear of ignition. Since carbon dioxide gas is excellent in resin solubility, the effect of lowering the viscosity of the resin is great. On the other hand, even if the exhausted carbon dioxide gas leaks into the atmosphere, it hardly affects the environment and is less dangerous.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the extruder is a twin-screw type twin screw extruder, but it may be a single screw extruder or a multi-screw extruder such as a tri-screw extruder.
In the above embodiment, polycarbonate pellets, stearyl alcohol powder, and calcium stearate powder previously mixed are supplied to the extruder as raw materials. However, each may be supplied individually.
In addition, the carbon nano-striates and the aliphatic alcohol are previously dispersed in a resin plasticizing gas atmosphere, and are supplied to the matrix resin-filled area of the extruder together with the resin plasticizing gas and mixed with the matrix resin with stirring. It doesn't matter.

In the above embodiment, after the resin plasticizing gas supplied into the extruder 4 is discharged from the gas discharge port 43 provided at the terminal portion of the extruder 4, the melt-kneaded product is pushed out from the pelleting die D. However, after the melt-kneaded product is extruded from the die D, the resin plasticizing gas may be gradually evaporated from the matrix resin.
In the above embodiment, the pellets 5b are obtained by extruding the pellets 5b using the pelleting die D, but directly forming the desired shape such as a film or sheet using a T die, a round die, a modified die, or the like. You may make it get goods.
Hereinafter, specific examples of the present invention will be described.

(Examples 1-7)
Polycarbonate (Iupilon (S-3000) manufactured by Mitsubishi Engineering Plastics), stearyl alcohol (STAL manufactured by Katsuta Chemical Co., Ltd.), calcium stearate (EC-102 manufactured by Eishin Kasei Co., Ltd.) as shown in Table 1 is 100: 0. Each of them was mixed with a Henschel mixer at a ratio of 2 to 1.2: 0.5, and charged into the hopper 1 shown in FIG.
Carbon nano-striates (made by Showa Denko Co., Ltd., vapor-grown carbon fiber VGCF d = 150 nm, L = 1 to 10 μm) were put into a hopper 2 shown in FIG. The weight type feeders 11 and 12 were adjusted so that the final carbon nanotube content was 7 wt%, and dropped into the hopper 3.

As shown in FIG. 1, the mixture is rotated in the same direction by a twin-screw extruder 4 (made by Plastic Engineering Laboratory Co., Ltd.) having seven cylinder units C1 to C7 each having a length of 20 cm, a head H, and a die D. SBTN-30-S2-60-L) is fed at an extrusion rate of 5 kg / hr from the raw material supply port 41 provided at C1, and melted and kneaded in the extruder 4 at a screw speed of 300 rpm. As shown in FIG. 1, resin composition pellets having a diameter of 3.0 mm and a length of 3.0 mm were obtained through a belt conveyor 6 and a pelletizer 7.
(Example 8)

    High-pressure (8.0 MPa) carbon dioxide gas was supplied at a concentration of 5% with respect to the resin weight from the gas injection port 42 opened in the portion C3 where the resin of the extruder 4 was filled. Resin composition pellets were obtained in the same manner as in Example 1 except that the gas was discharged by the vacuum pump 43 from the gas discharge port 43 opened in the C7 portion.

(Comparative Example 1)
Resin composition pellets were obtained in the same manner as in Example 1 except that stearyl alcohol was not supplied.

(Comparative Example 2)
Resin composition pellets were obtained in the same manner as in Example 8 except that stearyl alcohol was not supplied.

  The insulation resistance values (unit: Ω) of the pellets obtained in Examples 1 to 8 and Comparative Examples 1 and 2 were measured, and the results are shown in Table 1 together with the drive current value of the screw drive motor.

[Measurement of insulation resistance of pellet]
The insulation resistance value is calculated from the resistance value (average value of n number 5) 5 minutes after the voltage application is started at an applied voltage of 500 V by applying electrodes to both bottom surfaces of the cylindrical pellet with an insulation resistance meter PDM-506PK manufactured by Sanwa Co., Ltd. did.

From Table 1, it can be seen that by adding 0.5 part of stearyl alcohol to 100 parts of polycarbonate, the electrical insulation resistance of the polycarbonate mixture in which 7 parts of carbon nanotubes are dispersed and kneaded in an extruder is reduced by one digit.
It can also be seen that by adding stearyl alcohol, a uniformly dispersed carbon nanotube-dispersed polycarbonate composition can be obtained without using large power to disperse the carbon nanotubes.

  Further, it is understood that a resin composition having higher conductivity can be obtained by adding 0.5 part of stearyl alcohol to 100 parts of polycarbonate and kneading 7 parts of carbon nanotubes in the presence of carbon dioxide gas.

According to the method for producing a carbon nano-striated dispersion resin composition of the present invention, a carbon nano-striated resin composition uniformly dispersed without using a large power to disperse the carbon nano-striate, It can be manufactured easily. For this reason, it can use suitably for manufacture of the molded article which requires electroconductivity, or the intermediate material for it.
Furthermore, since a resin composition having high conductivity can be obtained even by adding a small amount of carbon nanostriates by kneading and dispersing in the presence of carbon dioxide, which is a resin plasticizing gas, a molded product having high conductivity or Therefore, the intermediate material can be manufactured at low cost.

It is a figure which represents typically one example of the apparatus used for the manufacturing method of the carbon nanotube dispersion | distribution resin composition which concerns on this invention.

Explanation of symbols

1, 2, 3 Hopper 11, 21 Weight feeder 4 Twin screw extruder 41 Raw material supply port 42 Gas injection port 43 Gas discharge port 44 Screw D Strand die 5a Strand 5b Pellet 6 Conveyor 7 Pelletizer

Claims (4)

  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 a step of kneading the matrix resin and the carbon nano-striates in the presence of an aliphatic alcohol. A method for producing a carbon nanowire-dispersed resin composition, which is characterized.   In a method for producing a carbon nano-striated dispersion resin composition in which carbon nano-striates are dispersed and mixed in a matrix resin, the matrix resin, the carbon nano-striates and an aliphatic alcohol are kneaded in the presence of a resin plasticizing gas. A process for producing a carbon nanowire-dispersed resin composition comprising a step.   The method for producing a carbon nanowire-dispersed resin composition according to claim 1 or 2, wherein the aliphatic alcohol is a saturated or unsaturated aliphatic alcohol having 12 to 22 carbon atoms.   The method for producing a carbon nanowire-dispersed resin composition according to claim 2 or 3, wherein the resin plasticizing gas is carbon dioxide.

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