JP2005298553A - Method for mixing resin material with carbon nano material and device for mixing them - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mixing technology for mixing a resin material with a carbon nano material, without requiring pelletization and capable of shortening the number of processes. <P>SOLUTION: A device 20 for mixing the resin material with carbon nano material consists of a hopper-formed container 24, a heater 25 pasted on the container 24, a heat-insulating material 26 covering the heater 25, a temperature sensor 27 installed at the container 24 for measuring the inside temperature of the container 24, a temperature-controlling part 28 for regulating the output of the heater 25 so that the temperature detected by the temperature sensor 27 becomes a prescribed temperature, and an agitating means 30 for agitating the materials in the container 24. Thereby, since the carbon nano material adheres to the surrounding of the resin material, there is no fear of the aggregation of the carbon nano material each other, and as a result, it is possible to disperse the carbon nano material uniformly in the resin material. Since the treatment is performed by substantially one process of mixing while heating, the cost of mixing can be reduced remarkably. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a mixing technique of a resin material and a carbon nanomaterial.

  In recent years, attention has been focused on a technique for making a special carbon fiber called a carbon nanomaterial into a conductive plastic by mixing it into plastic, or a fiber reinforced metal by mixing it into molten metal.

  FIG. 7 is a model diagram of a carbon nanofiber. A carbon nanofiber 110, which is a kind of carbon nanomaterial, has a shape in which a sheet of carbon atoms arranged in a hexagonal network is wound in a cylindrical shape and has a diameter D Is 1.0 nm (nanometers) to 150 nm and is at the nano level, so it is called a carbon nanomaterial. The length L is several μm to 100 μm.

  A diamond is a very hard substance in which carbon atoms are arranged in a cubic lattice. Since the carbon nanofiber 110 has a regular crystal structure like diamond, the mechanical strength is large. Carbon is used for electrodes and the like because it conducts electricity well.

However, as described above, since the carbon nanomaterial is ultrafine, it has a characteristic that it is easy to aggregate and difficult to disperse as compared with a micron-order carbon powder, so that it is difficult to handle.
Then, the technique of pelletizing and inject-molding using this pellet is proposed (for example, refer patent document 1).
JP 2003-319488 A (paragraph number [0035], paragraph number [0036])

  In paragraph No. [0035], lines 3 to 6, of Patent Document 1, “..., first, pellets in which carbon nanotubes are uniformly dispersed in a biaxial kneader in a resin having good adhesiveness are prepared, and then polypropylene. In a paragraph number [0036], “Pellets obtained in this way are generally used by an injection molding method, an extrusion molding method, etc.” The diaphragm of the present invention can be molded. "

From these descriptions, it can be seen that the invention of Patent Document 1 is a technique for manufacturing a molded product through the steps of material preparation → kneading → pellet → polypropylene addition → injection or extrusion molding.
Once pelletized, the handling of the carbon nanomaterial is facilitated, and the pellets are transported and stocked, so that when necessary, the pellets can be used as a starting material for injection molding or extrusion molding. There are advantages.

However, since there are many processes, manufacturing cost increases.
In addition, a difference frequently occurs between the carbon nanomaterial content in the stocked pellets and the carbon nanomaterial content required for the molded product. In this case, the carbon nanomaterial or the resin material is mixed in the pellet and supplied to the molding machine. This makes it difficult to uniformly disperse the carbon nanomaterial or resin material in the pellets, which adversely affects the quality of the molded product.

  Therefore, a mixing technique that requires a short number of steps and does not require pelletization is required.

  An object of the present invention is to provide a technique capable of reducing the number of steps without requiring pelletization in a mixing technique of mixing a resin material and a carbon nanomaterial.

  The invention according to claim 1 is a mixing method in which a resin material and a carbon nanomaterial are mixed, and the resin material and the carbon nanomaterial are mixed and maintained at a temperature at which the entire surface of the resin material is softened. It is characterized in that a carbon nanomaterial is attached to the surface of the film.

  According to a second aspect of the present invention, there is provided a mixing apparatus for mixing a resin material and a carbon nanomaterial, wherein the mixing apparatus includes a container for storing the resin material and the carbon nanomaterial, and an internal temperature of the container for the surface of the resin material. It is characterized by comprising a heater and a temperature control unit that maintain a temperature at which the whole is softened, and stirring means for stirring the material in the container.

  The invention according to claim 3 is characterized in that the mixing device is a hopper of an injection mechanism.

  In the invention according to claim 1, the resin material and the carbon nanomaterial are maintained at a temperature at which the entire surface of the resin material is softened, and the surface of the resin material is imparted with adhesiveness. Then, a carbon nanomaterial is attached to the surface of the resin material.

Since the carbon nanomaterial adheres around the resin material, there is no possibility that the carbon nanomaterials aggregate with each other, and as a result, the carbon nanomaterial can be uniformly dispersed in the resin material.
Since it can process by one process of mixing while heating, mixing cost can be reduced significantly.
That is, a mixture of a resin material and a carbon nanomaterial can be obtained in one step without requiring a pelletizing step, and the number of steps can be greatly reduced.

  In the invention which concerns on Claim 2, a mixing apparatus is comprised with a container, a heater and a temperature control part, and a stirring means. The device configuration is very simple and the device cost can be reduced.

  The invention according to claim 3 is characterized in that the mixing device is a hopper of an injection mechanism, and the resin material and the carbon nanomaterial can be replaced with the existing injection mechanism only by replacing the mixing device of the present invention at the position of the hopper. The mixture can be injected.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. The drawings are viewed in the direction of the reference numerals.
FIG. 1 is a manufacturing flow diagram according to the present invention, where STxx indicates a step number.
ST01: First, a predetermined amount of resin material and carbon nanomaterial are prepared. The resin material is desirably a material having a large surface area such as powder or granular material.
ST02: The resin material and the carbon nanomaterial are put into a mixer and mixed while maintaining a temperature at which the entire surface of the resin material is softened.
Thus, a mixture can be obtained.

  If the resin material is polypropylene, the temperature at which the entire surface of the resin material softens is 160 to 170 ° C., and the heating temperature is 140 to 160 ° C. Further, if the resin material is PET (polyethylene terephthalate), the melting point temperature is preferably 253 to 265 ° C, and the heating temperature is preferably 200 to 210 ° C.

FIG. 2 is a schematic view of a mixture obtained by the method of the present invention. The mixture 10 is a resin material 11 with a myriad of carbon nanomaterials 12 attached to the surface thereof.
For example, it is the structure of the mixture 10 according to the present invention that the “koji” of the kana powder koji corresponds to the resin material 11 and the “kinako” corresponds to the carbon nanomaterial 12, and the non-adhesive powder on the koji surface is adhered. Similar to.

A mixing apparatus suitable for realizing the above-described method of the present invention will be described below.
FIG. 3 is a cross-sectional view of the mixing apparatus according to the present invention. The mixing apparatus 20 includes a hopper-shaped container 24 having a lid 23 provided with a charging port 21 for the resin material 11 and a charging port 22 for the carbon nanomaterial 12. The heaters 25 attached to the container 24 (... indicates a plurality; the same applies hereinafter), the heat insulating material 26 covered with the heaters 25, and the internal temperature of the container 24 are measured. Therefore, the temperature sensor 27 provided in the container 24, the temperature control unit 28 for controlling the output of the heaters 25 ... so that the temperature detected by the temperature sensor 27 becomes a predetermined temperature, and the material in the container 24 are agitated. And mixing means 30 (details will be described later).

  In consideration of corrosion resistance, the material of the container 24 is preferably stainless steel rather than carbon steel.

  The stirring means 30 includes a stirring motor 32 attached to the lid 23 so that the motor shaft 31 faces downward, a rotating shaft 34 inserted from below into a bearing ring 33 provided on the lid 23, and provided in the middle of the rotating shaft 34. Bosses 35, 35, agitating blades 36 projecting radially from the boss 35, lower agitating blades 38, 38 for agitating the bottom of the container 24, and a lower end of the rotating shaft 34 for rotatably supporting And a shaft support bracket 37 extending from the container 24. Reference numeral 50 denotes a heat insulating structure (details will be described later), which is not an essential element, but is preferably interposed on the rotating shaft 34.

The operation of the mixing apparatus 20 having the above configuration will be described next.
First, the heaters 25... Are energized and controlled by the temperature control unit 28 to keep the internal temperature of the container 24 at a temperature at which the entire surface of the resin material is softened.
In this state, the stirring motor 32 is started, and the rotating shaft 34, the stirring blades 36, and the lower stirring blades 38 are continuously rotated at a predetermined speed. The valves 41, 42 and 43 are closed.

The valve 41 is opened, a predetermined amount of the resin material 11 is introduced from the inlet 21, the valve 42 is opened, the predetermined amount of the carbon nanomaterial 12 is introduced from the inlet 22, and the valves 41, 42 are closed.
While stirring with the stirring blades 36... And the lower stirring blades 38... And heating with the heaters 25. Then, the carbon nanomaterial 12 adheres to the surface of the resin material 11. If necessary, the mixture 10 can be dropped by opening the valve 43.

  FIG. 4 is an enlarged view of the heat insulating structure according to the present invention. The heat insulating structure 50 is a member that thermally cuts the rotary shaft 34 into a very short upper shaft 44 and a long lower shaft 45, and includes an upper flange. 51, a heat insulating plate 52, a lower flange 53, and bolts / nuts 54.

The rotating shaft 34, the stirring blades 36, and the lower stirring blades 38 are metal members such as carbon steel and stainless steel from the viewpoint of strength. Since metal has a higher thermal conductivity than ceramics or resin, heat escapes upward via the motor shaft 31, and as a result, the center of the container 24 (see FIG. 3) may become cold.
At this time, if the heat insulating structure 50 is employed, heat conduction from the lower shaft 45 to the upper shaft 44 can be blocked. As a result, the temperature inside the container 24 can be made uniform.

Returning to FIG. 3, it is desirable that the rotating shaft 34, the stirring blades 36, and the lower stirring blades 38 are made of an aluminum alloy or a copper alloy having a thermal conductivity higher than that of carbon steel. This is because the heat generated by the heaters 25 can be quickly transmitted to the center of the container 24.
However, as long as heat moves from the heaters 25 to the center of the container 24, the center of the container 24 has the lowest temperature. In order to solve this problem, the following structure is effective.

  FIG. 5 is a diagram showing another embodiment of the rotating shaft according to the present invention. A rod-shaped heater 55 is built in the lower shaft 45 of the rotating shaft 34, and feeding lines 56, 57 to the rod-shaped heater 55 are connected to feeding rings 58, 59. These power supply rings 58 and 59 are fitted to the lower shaft 45. On the other hand, power supply brushes 62 and 63 are provided on the bracket 61 extending from the container side, and the power supply brushes 62 and 63 are slidably contacted with the power supply rings 58 and 59 so that power can be supplied to the rotating shaft 34. The rod heater 55 is a metal tube heater in which a metal tube is filled with an insulating material, and a string-like heating element is embedded in the insulating material, and does not require an insulation treatment.

  If the rotary shaft 34 is heated by the rod heater 55, the center and the outer periphery of the container 24 in FIG. 3 can be heated simultaneously, and the internal temperature of the container 24 can be easily made uniform. Even in this case, it is desirable that the rotating shaft 34, the bosses 35 and 35, the stirring blades 36, and the lower stirring blades 38 are made of a good heat conductive material such as a copper alloy. Then, the resin material and the carbon nanomaterial can be mixed at a more uniform temperature.

The heater 55 that heats the rotating shaft 34 may be a surface heater or a ribbon heater in addition to a rod heater, and may have any shape and structure. In short, it is a means that can directly heat the rotating shaft 34. I just need it.
In addition, when the heat insulating structure 50 is interposed on the upper portion of the rotating shaft 34, the bearing portion 64 that directly supports the lower end of the rotating shaft 34 in the lower shaft support bracket 37 is converted into ceramics to have a heat insulating structure. It is desirable to do.

FIG. 6 is a diagram showing an example in which the mixing apparatus of the present invention is applied to an injection mechanism. There are various types of resin injection mechanisms, one of which is a preliminary plasticization (generally referred to as pre-plastic) type injection mechanism.
The pre-plastic injection mechanism 70 includes a pre-plastic portion 73 in which a pre-plastic screw 72 is incorporated in a pre-plastic cylinder 71 and a plunger 75 in an injection cylinder 74. The injection machine is capable of injecting the material plasticized in advance in the pre-plastic part 73 by the injection part 77.

  By mounting the mixing device 20 of the present invention on the base of the pre-plastic cylinder 71, the mixture (see FIG. 2) in which the carbon nanomaterial 12 is adhered to the resin material 11 can be directly supplied to the injection mechanism 70. it can. The injection mechanism 70 may be a screw-type injection mechanism in addition to the pre-plastic injection mechanism, and may be of any type as long as it is an injection mechanism used for resin injection molding.

  In addition, the mixing apparatus of this invention can be utilized as an apparatus which manufactures a mixture as a single unit besides mounting in an injection mechanism, The use is not specifically limited.

  The present invention is suitable for a mixing apparatus for mixing a carbon nanomaterial with a resin material.

It is a manufacturing flow figure concerning the present invention. It is a schematic diagram of the mixture obtained by the method of the present invention. It is sectional drawing of the mixing apparatus which concerns on this invention. It is an enlarged view of the heat insulation structure which concerns on this invention. It is another Example figure of the rotating shaft which concerns on this invention. It is a figure which shows the example which applied the mixing apparatus of this invention to the injection mechanism. It is a model figure of a carbon nanofiber.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Mixture, 11 ... Resin material, 12 ... Carbon nanomaterial, 20 ... Mixing device, 24 ... Container, 25 ... Heater, 27 ... Temperature sensor, 28 ... Temperature control part, 30 ... Stirring means, 34 ... Rotating shaft, 36 ... stirring blade, 38 ... lower stirring blade.

Claims (3)

In a mixing method of mixing a resin material and a carbon nanomaterial,
The resin material and the carbon nanomaterial are maintained at a temperature at which the entire surface of the resin material is softened and mixed to adhere the carbon nanomaterial to the surface of the resin material. Mixing method. In a mixing device that mixes resin materials and carbon nanomaterials,
The mixing apparatus includes a container for storing the resin material and the carbon nanomaterial, a heater and a temperature control unit for maintaining the internal temperature of the container at a temperature at which the entire surface of the resin material is softened, and stirring for stirring the material in the container. And a mixing device of the resin material and the carbon nanomaterial.   The mixing device for a resin material and a carbon nanomaterial according to claim 2, wherein the mixing device is a hopper of an injection mechanism.

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