WO2021220628A1

WO2021220628A1 - Carbon-fiber-reinforced plastic structure and method for producing same

Info

Publication number: WO2021220628A1
Application number: PCT/JP2021/009329
Authority: WO
Inventors: 米太田中
Original assignee: ウシオ電機株式会社
Priority date: 2020-04-28
Filing date: 2021-03-09
Publication date: 2021-11-04
Also published as: JP2021172763A

Abstract

Provided are a carbon-fiber-reinforced plastic structure having no anisotropy in thermal properties, and a method for producing said structure. The carbon-fiber-reinforced plastic structure (CFRP structure) (10) comprises a prepreg (11) in which carbon fibers (11a) are impregnated with a resin (11b). The resin (11b) includes thermally conductive granules (12) having a diameter smaller than the diameter of the carbon fibers (11a), and the granules (12) are present at 4 wt% or higher relative to the total weight of the carbon-fiber-reinforced plastic structure (10).

Description

Carbon fiber reinforced plastic structure and its manufacturing method

The present invention relates to a carbon fiber reinforced plastic structure containing carbon fiber reinforced plastic and a method for manufacturing the structure.

Conventionally, carbon fiber reinforced plastic (CFRP) is known as a material having characteristics such as high specific rigidity and low density and thermal expansion coefficient. Applied research is progressing on CFRP as an alternative material to metals.
CFRP is made, for example, as follows.
First, carbon fibers are impregnated with resin to prepare a plate-shaped (sheet-shaped) material called a prepreg. Next, a plurality of prepregs are stacked in a mold while considering the direction of the fibers, and then heated, crimped, and cured to form the prepreg. Then, after cooling, the molded product is removed from the mold.

It has been proposed that the CFRP produced in this manner be used as a material for a stage of a processing apparatus that performs precision processing, for example (see, for example, Patent Document 1 (Japanese Patent Laid-Open No. 2019-51653)).

JP-A-2019-51653

One of the major differences between carbon fiber reinforced plastic structures containing CFRP (CFRP structures) and metals is thermal conductivity.
Metals are not anisotropy in the direction of heat transfer. On the other hand, the CFRP structure has good thermal conductivity only in the direction in which the carbon fibers extend (X direction), and the direction orthogonal to the direction in which the carbon fibers extend (Y direction) and the direction in which the prepregs are stacked (Z direction). ), The thermal conductivity is poor. The thermal conductivity in the Y direction and the Z direction basically depends on the thermal conductivity of the resin impregnated in the carbon fibers. Resins generally have poorer thermal conductivity than metals and carbon fibers.
Therefore, there is a desire to improve the thermal conductivity of the CFRP structure in all directions. If the CFRP structure can transfer heat without anisotropy like metal, it is expected that the range of application will be further expanded as a substitute for metal.

An object of the present invention is to provide a carbon fiber reinforced plastic structure having no anisotropy in thermal properties, and a method for producing the structure.

In order to solve the above problems, one aspect of the carbon fiber reinforced plastic structure according to the present invention is a carbon fiber reinforced plastic structure including carbon fibers impregnated with a resin, and the resin is the carbon fiber. It contains thermally conductive particles having a diameter smaller than the diameter, and the particles are present in an amount of 4% by weight or more based on the total weight of the carbon fiber reinforced plastic structure.
Such a carbon fiber reinforced plastic structure (CFRP structure) has the characteristics of carbon fiber reinforced plastic such as high specific rigidity and low density and thermal expansion coefficient. Further, since the resin contains a large number of thermally conductive particles, good thermal conductivity can be obtained in a direction other than the direction in which the carbon fibers are stretched. That is, it is possible to realize a carbon fiber reinforced plastic structure having no anisotropy in thermal properties.

Further, in the carbon fiber reinforced plastic structure, the granules may be made of diamond. In this case, the thermal conductivity can be improved without deteriorating the original characteristics of the carbon fiber reinforced plastic such as high specific rigidity and low density and coefficient of thermal expansion.
Further, in the carbon fiber reinforced plastic structure, the granules may be made of copper. In this case, the thermal conductivity can be effectively improved.

Further, one aspect of the carbon fiber reinforced plastic structure according to the present invention is a carbon fiber reinforced plastic structure including carbon fibers impregnated with a resin, and the resin has a diameter smaller than the diameter of the carbon fibers. The heat conductive particles having the above are injected.
Such a carbon fiber reinforced plastic structure (CFRP structure) has the characteristics of carbon fiber reinforced plastic such as high specific rigidity and low density and thermal expansion coefficient. Further, since the heat conductive particles are injected into the resin, good heat conductivity can be obtained in a direction other than the direction in which the carbon fibers are stretched. That is, it is possible to realize a carbon fiber reinforced plastic structure having no anisotropy in thermal properties.

Further, one aspect of the method for producing a carbon fiber reinforced plastic structure according to the present invention is a method for producing a carbon fiber reinforced plastic structure including carbon fibers impregnated with a resin, wherein the carbon fibers are impregnated with the resin. In the first step of preparing the prepreg, the second step of adhering the thermally conductive particles having a diameter smaller than the diameter of the carbon fiber to the prepreg, and the second step. A third step of injecting the granules into the resin by stacking a plurality of the prepregs to which the granules are attached and applying pressure while heating is included.
As a result, it is possible to manufacture a structure having characteristics of carbon fiber reinforced plastic such as high specific rigidity, low density and low coefficient of thermal expansion, and having good thermal conductivity in any direction.

Further, one aspect of the method for producing a carbon fiber reinforced plastic structure according to the present invention is a method for producing a carbon fiber reinforced plastic structure including carbon fibers impregnated with a resin, wherein the carbon fibers and the resin are combined. The first step of preparing, the second step of injecting the heat conductive particles having a diameter smaller than the diameter of the carbon fibers into the resin, and the second step of injecting the particles into the carbon fibers. The third step of impregnating the resin and the fourth step of stacking a plurality of the carbon fibers impregnated with the resin in the third step and applying pressure while heating are included.
As a result, it is possible to manufacture a structure having characteristics of carbon fiber reinforced plastic such as high specific rigidity, low density and low coefficient of thermal expansion, and having good thermal conductivity in any direction.

Further, in the above method for producing a carbon fiber reinforced plastic structure, the amount of the granules may be 4% by weight or more with respect to the total weight of the carbon fiber reinforced plastic structure.
In this case, the thermal conductivity can be appropriately improved.

According to the present invention, it is possible to improve thermal conductivity in a direction orthogonal to the extending direction of carbon fibers, and to realize a carbon fiber reinforced plastic structure having no anisotropy in thermal properties. Can be done.
The above-mentioned purpose, aspect and effect of the present invention and the above-mentioned purpose, aspect and effect of the present invention not described above will be used by those skilled in the art to carry out the following invention by referring to the accompanying drawings and the description of the scope of claims. Can be understood from the form of (detailed description of the invention).

FIG. 1 is a diagram schematically showing a carbon fiber reinforced plastic structure of the present embodiment. FIG. 2 is a diagram schematically showing a prepreg. FIG. 3 is a diagram schematically showing a prepreg to which granules are attached. FIG. 4 is a diagram showing one step of a method for manufacturing a carbon fiber reinforced plastic structure. FIG. 5 is an image diagram of a process of injecting granules into the resin.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view schematically showing a carbon fiber reinforced plastic structure (CFRP structure) 10 of the present embodiment.
As shown in FIG. 1, the CFRP structure 10 is configured by laminating a plurality of prepregs 11. The prepreg 11 is a sheet-like member in which carbon fibers 11a are impregnated with resin 11b while maintaining the directionality of the fibers. The resin 11b constituting the prepreg 11 is, for example, a thermosetting epoxy resin. As the resin 11b constituting the prepreg 11, for example, a thermosetting resin such as unsaturated polyester, vinyl ester, phenol, cyanate ester, or polyimide can be used.

FIG. 1 shows a CFRP structure 10 in which five prepregs 11 are laminated in the same direction in which the carbon fibers 11a extend, in order to simplify the explanation. In FIG. 1, the cross section of the carbon fiber 11a is indicated by a white circle. In FIG. 1, the X direction is the direction in which the carbon fibers 11a are stretched, the Y direction is the direction orthogonal to the direction in which the carbon fibers 11a are stretched, and the Z direction is the stacking direction of the prepreg 11.
The CFRP structure 10 may be formed by alternately stacking the prepregs 11 one by one so that the directions in which the carbon fibers 11a extend are orthogonal to each other. The crossing angle and the ratio of the orientation directions of the carbon fibers 11a when laminating the prepreg 11 can be arbitrarily set.

In the CFRP structure 10 of the present embodiment, a large number of thermally conductive particles 12 having a diameter smaller than the diameter of the carbon fibers 11a are injected into the resin 11b constituting the prepreg 11.
Here, the grain 12 is, for example, diamond powder. Diamond powder is a powder of diamond. Since diamond has high thermal conductivity, it can be said that diamond powder is a granular material having thermal conductivity.

Hereinafter, an example of the method for producing the CFRP structure 10 in the present embodiment will be described.
First, as shown in FIG. 2, a prepreg 11'in which carbon fibers are impregnated with a resin is prepared. Here, the prepreg 11'may be, for example, a commercially available prepreg. As the prepreg 11', for example, a UD (UNI-DIRECTION) material can be used. Here, the UD material is a material in which the direction of the fiber extends in only one direction.
Next, prepare diamond powder. Here, the diameter of the diamond powder is smaller than the diameter of the carbon fibers used in the prepreg 11'. Considering the influence on the living body, carbon fibers having a diameter of 5 μm or less are not used. Therefore, the diameter of the diamond powder is, for example, 5 μm or less. When the diameter of the carbon fiber is, for example, 7 μm to 10 μm, the diameter of the diamond powder can be, for example, 2 μm to 4 μm.

Next, the prepreg 11'is heated, and as shown in FIG. 3, the diamond powder 12 is attached to the surface of the prepreg 11'. When the preprig 11'is heated, the resin constituting the preprig 11'softens and the diamond powder 12 easily adheres to the preprig 11'. The diamond powder 12 shown in FIG. 3 is shown extremely large so that it can be easily seen as a figure.
Next, as shown in FIG. 4, a plurality of prepregs 11'with the diamond powder 12 attached are laminated in the mold 20. The number of laminated sheets can be, for example, 10 to 50 sheets. In FIG. 4, the number of laminated prepregs 11'is extremely small so that it can be easily seen as a figure. Then, while heating, high pressure is applied in the stacking direction of the prepreg 11'and crimping is performed.

As a result, a part of the resin 11b between the carbon fibers 11a and the carbon fibers 11a constituting the prepreg 11'is extruded, and the diamond powder 12 is injected therein. That is, as shown in FIG. 5, the diamond powder 12 adhering to the surface of the prepreg 11'enters the stacking direction of the prepreg 11'.
As a result, the CFRP structure 10 in which a plurality of prepregs 11 made of carbon fibers 11a impregnated with the resin 11b in which the diamond powder 12 is injected is laminated is manufactured.

The CFRP structure 10 has the original characteristics of CFRP such as high specific rigidity, low density and low coefficient of thermal expansion.
In particular, the CFRP structure 10 in the present embodiment contains a large number of thermally conductive particles 12 in which the resin 11b constituting the prepreg 11 has a diameter smaller than the diameter of the carbon fibers 11a. With such a configuration, not only the direction in which the carbon fiber 11a extends (X direction), but also the direction orthogonal to the direction in which the carbon fiber 11a extends (Y direction) and the stacking direction of the prepreg 11 (Z direction). Thermal conductivity can be improved and heat can be transferred isotropically.

As a result of diligent studies, the present inventor considered applying the percolation effect to the CFRP structure. The percolation effect is, for example, when small particles having conductivity are filled in a non-conductive substance (for example, resin), and when the filling amount reaches a certain amount, the conductivity suddenly becomes conductive. It is the effect of improving.
Similar to this phenomenon, if the CFRP structure contains particles of a substance with good thermal conductivity, it is thought that good thermal conductivity can be obtained in directions other than the direction in which the carbon fibers are stretched. rice field.
In order to verify this, the present inventor investigated the thermal conductivity of each of the CFRP structure containing no particles having thermal conductivity and the CFRP structure containing particles having thermal conductivity. ..

(Example)
The thermal conductivity of a conventional CFRP structure containing no particles having thermal conductivity and a CFRP structure in which diamond powder was injected as particles having thermal conductivity were evaluated. The results are shown in Table 1. Here, the numerical value of the thermal conductivity was calculated from the thermal diffusivity, the specific heat, and the density of each sample. A xenon flash analyzer was used to measure the thermal diffusivity.

The comparative example in Table 1 is a conventional CFRP structure and does not contain diamond powder. As the prepreg constituting the CFRP structure, E8025C-25N (resin content (RC): 32 wt%, fiber volume content (Vf): 54 vol%) manufactured by Nippon Graphite Fiber Corporation was used.
In Example 1, diamond powder is injected into a CFRP structure having the same structure as that of Comparative Example. In this Experimental Example 1, 0.456 g (about 4.02% by weight) of diamond powder is injected into 11.333 g of the CFRP structure.
In Example 2, diamond powder is injected into a CFRP structure having the same structure as that of Comparative Example. In this Experimental Example 2, 0.588 g (about 5.20% by weight) of diamond powder is injected into 11.312 g of the CFRP structure.
In each sample, the CFRP structure is a stack of 40 prepregs.

As shown in Table 1, the thermal conductivity of the comparative example without diamond powder is 1.23 W / (mK), whereas the thermal conductivity of Example 1 containing about 4.02 wt% diamond powder is 1.23 W / (mK). Was 2.07 W / (mK). That is, the thermal conductivity of the CFRP structure of Example 1 was about 1.7 times that of the CFRP structure of Comparative Example.
Further, in Example 2 in which the amount of diamond powder was increased and the amount of diamond powder was about 5.20 wt%, the thermal conductivity was 2.22 W / (mK). That is, the thermal conductivity of the CFRP structure of Example 2 was about 1.8 times the thermal conductivity of the CFRP structure of Comparative Example.

From the above experimental results, it was confirmed that the CFRP structure infused with diamond powder can increase the thermal conductivity as compared with the CFRP structure in which diamond powder is not injected.
It was also confirmed that the thermal conductivity can be appropriately improved by injecting the granules 12 in an amount of 4% by weight or more based on the total weight of the CFRP structure. Furthermore, it was also confirmed that the thermal conductivity can be further improved by increasing the amount of the granules 12 injected.

In the CFRP structure in which the particles having thermal conductivity are not injected, such as the CFRP structure of the above comparative example, the direction in which the thermal conductivity is good is only in the direction in which the carbon fibers are elongated, and in the direction in which the carbon fibers are elongated. On the other hand, the thermal conductivity is poor in the direction orthogonal to the prepreg and the stacking direction of the prepreg.
On the other hand, in the CFRP structure 10 of the present embodiment, the resin 11b constituting the prepreg 11 is injected with diamond powder 12, which is a thermally conductive particle having a diameter smaller than the diameter of the carbon fiber 11a. Has a configuration. The diamond powder 12 having a diameter smaller than the diameter of the carbon fibers 11a enters the gap between the carbon fibers 11a and the carbon fibers 11a and causes a percoration effect. Therefore, heat in a direction other than the direction in which the carbon fibers are stretched (X direction in FIG. 1), for example, a direction (Y direction, Z direction in FIG. 1) orthogonal to the direction in which the carbon fibers are stretched (X direction in FIG. 1). Conductivity can be improved.

As described above, the CFRP structure 10 in the present embodiment has the original characteristics of CFRP such as high specific rigidity and low density and coefficient of thermal expansion, and also has good heat conduction in directions other than the direction in which carbon fibers are stretched. A structure having properties and having no anisotropy in thermal properties can be obtained.

(Modification example)
In the above embodiment, the case where the CFRP structure 10 in which the diamond powder 12 is injected is produced by the following procedure has been described.
First step: Prepare the prepreg 11'.
Second step: The diamond powder 12 is attached to the surface of the prepreg 11'.
Third step: A plurality of prepregs 11'to which the diamond powder 12 is attached are stacked and pressure is applied while heating to inject the diamond powder 12 into the resin of the prepreg 11'.
However, the method for producing the CFRP structure 10 is not limited to the above. For example, the CFRP structure 10 can be manufactured by the following procedure.
First step: The carbon fiber 11a and the resin 11b are prepared.
Second step: Diamond powder 12 is injected into the resin 11b.
Third step: The carbon fiber 11a is impregnated with the resin 11b in which the diamond powder 12 is injected to prepare the prepreg 11.
Fourth step: A plurality of prepregs 11 are stacked and pressure is applied while heating.

Further, in the above embodiment, the case where diamond is used as the granular material having thermal conductivity has been described, but for example, a metal such as copper can also be used. Copper is suitable because it has high thermal conductivity.
However, when a substance other than carbon fiber is mixed with the prepreg, the characteristics such as high rigidity, low density, and low coefficient of thermal expansion, which are the characteristics of CFRP, may be deteriorated depending on the characteristics and amount of the substance to be mixed. Therefore, careful consideration is required for the material.
The diamond powder used in the above embodiment is preferable because it not only has good thermal conductivity but also has high rigidity, and even if it is injected into a prepreg, it has little effect on the characteristics of CFRP.

Although a specific embodiment is described above, the embodiment is merely an example, and there is no intention of limiting the scope of the present invention. The devices and methods described herein can be embodied in forms other than those described above. Further, without departing from the scope of the present invention, omissions, substitutions and changes can be made as appropriate with respect to the above-described embodiments. Such abbreviations, substitutions and modifications are included in the claims and equivalents thereof and fall within the technical scope of the invention.

10 ... Carbon fiber reinforced plastic structure (CFRP structure), 11 ... Prepreg, 11a ... Carbon fiber, 11b ... Resin, 12 ... Granules

Claims

A carbon fiber reinforced plastic structure having carbon fibers impregnated with resin.
The resin contains thermally conductive granules having a diameter smaller than the diameter of the carbon fibers.
A carbon fiber reinforced plastic structure characterized in that the granules are present in an amount of 4% by weight or more based on the total weight of the carbon fiber reinforced plastic structure.
The carbon fiber reinforced plastic structure according to claim 1, wherein the granules are made of diamond.
The carbon fiber reinforced plastic structure according to claim 1, wherein the granules are made of copper.
A carbon fiber reinforced plastic structure having carbon fibers impregnated with resin.
A carbon fiber reinforced plastic structure characterized in that heat conductive particles having a diameter smaller than the diameter of the carbon fibers are injected into the resin.
A method for manufacturing a carbon fiber reinforced plastic structure including carbon fibers impregnated with resin.
The first step of preparing a prepreg obtained by impregnating the carbon fiber with the resin, and
A second step of attaching thermally conductive particles having a diameter smaller than the diameter of the carbon fibers to the prepreg,
It is characterized by including a third step of injecting the granules into the resin by stacking a plurality of the prepregs to which the granules are attached in the second step and applying pressure while heating. A method for manufacturing a carbon fiber reinforced plastic structure.
A method for manufacturing a carbon fiber reinforced plastic structure including carbon fibers impregnated with resin.
The first step of preparing the carbon fiber and the resin, and
A second step of injecting thermally conductive particles having a diameter smaller than the diameter of the carbon fibers into the resin,
The third step of impregnating the carbon fiber with the resin in which the granules are injected, and
A method for producing a carbon fiber reinforced plastic structure, which comprises a fourth step of stacking a plurality of the carbon fibers impregnated with the resin in the third step and applying pressure while heating.
The method for producing a carbon fiber reinforced plastic structure according to claim 5 or 6, wherein the amount of the granules is 4% by weight or more with respect to the total weight of the carbon fiber reinforced plastic structure.