JP4509651B2 - Fiber surface modification method and apparatus - Google Patents

Description

  The present invention relates to a method for modifying the surface of a fiber (particularly, carbon fiber) using high-temperature high-pressure water, and an apparatus therefor.

Fiber reinforced resin using carbon fiber as a reinforcing material is lightweight and has excellent strength and elastic modulus, so it can be used in a wide range of fields such as sports and leisure components and spacecraft components. It is being advanced. When manufacturing such a fiber reinforced resin, in order to reinforce the interfacial adhesion between the carbon fiber and the matrix resin, the carbon fiber is subjected to treatments such as chemical oxidation treatment, vapor phase oxidation treatment, and electrolytic oxidation treatment. . By this treatment, oxygen is introduced and activated on the surface of the carbon fiber, and the adhesion to the resin is improved.
The present inventors have found that the surface modification of carbon fibers can be performed using a supercritical fluid or a subcritical fluid instead of the conventional oxidation treatment. For example, Japanese Patent Application Laid-Open No. 2002-180379 discloses that the surface can be modified by treating carbon fiber with a supercritical fluid or a subcritical fluid.

The method using a supercritical fluid or subcritical fluid is very effective for surface modification of carbon fibers. However, when a batch type (batch type) apparatus is used, it is difficult to ensure sufficient productivity. In order to solve this difficulty, it is desired to provide a continuous processing apparatus, but such an apparatus has not yet been developed.
The present invention has been made in view of the above circumstances, and an object thereof is a method capable of continuous treatment when surface modification of carbon fiber is performed using a supercritical fluid or a subcritical fluid, and therefore It is in providing the apparatus of.
JP 2002-180379 A

The fiber surface modification method according to the first aspect of the present invention for achieving the above object allows a fiber to pass through the inside of the pipe in a state where a supercritical fluid or a subcritical fluid is present inside the pipe. It is characterized by that.
The fiber to be treated in the present invention may be any of plastic fiber, silk fiber, carbon fiber (polyacrylonitrile (hereinafter referred to as PAN) carbon fiber, cellulosic carbon fiber, pitch carbon fiber, air-growth carbon fiber, etc. Carbon fiber) can also be used. When the fiber is a carbon fiber, the carbon fiber precursor is flameproofed in an oxidizing atmosphere, and then the flameproofed fiber is fired at 800 ° C. to 2000 ° C. in an inert gas atmosphere. PAN-based carbon fiber obtained by firing in a higher temperature inert gas is used. In general, carbon fibers are subjected to oxidation treatment such as electrolytic oxidation treatment and gas phase oxidation treatment after firing for the purpose of surface modification in order to increase the bonding strength with the resin, and are given a sizing agent. Later used for fiber reinforced resin. However, according to the present invention, surface modification can be performed by performing high-temperature and high-pressure treatment without performing such oxidation treatment.
Examples of the “fluid” include water, methanol, ethanol, carbon dioxide and the like, but the present invention is not limited to these. Of these fluids, water is preferably used.

  “Supercritical fluid” means a critical point of temperature, pressure, and entropy diagram in a phase diagram (for example, −268 ° C. and 0.23 MPa for helium, 31.1 ° C. and 7.38 MPa for carbon dioxide, and 374. It means a fluid in a supercritical state to which a temperature / pressure higher than 3 ° C., 22.1 MPa and ethanol (243.0 ° C., 6.14 MPa) are applied. The “subcritical fluid” means a fluid in which at least one of temperature and pressure is lower than the critical point, and the compressed gas and the compressed liquid coexist.

  “Pipe” means an elongated space through which fibers can pass while supercritical fluid or subcritical fluid is present in the internal space. The pressure of the supercritical fluid or subcritical fluid is several times to several hundred times the atmospheric pressure, although it depends on the type of fluid. For this reason, it is difficult to make a fluid into a supercritical state or a subcritical state under atmospheric pressure. The inventors of the present invention can maintain the pressure and temperature of the fluid in the pipeline in a supercritical state or a subcritical state by reducing the diameter of the pipeline, increasing the length of the pipeline, and increasing the flow rate of the fluid. I succeeded in raising it. Thus, by selecting appropriate conditions according to the fluid, the fluid in the pipeline can be brought into a supercritical state or a subcritical state.

  According to the present invention, the surface of the fiber is modified by passing the fiber through the pipe line in which the supercritical fluid or the subcritical fluid is present. This method is superior in productivity because the fiber can be processed continuously as compared with the conventional batch system.

The fiber surface modification device according to the second invention for achieving the above object is a pipe having a fiber inlet and outlet and a fluid inflow for flowing a fluid into the pipe. And a heat source device for bringing the fluid in the pipe line into a supercritical state or a subcritical state.
According to the present invention, the fluid introduced into the pipe line by the fluid inflow machine is in a supercritical state or a subcritical state in the pipe line by the heat source unit. Here, when the fiber introduced from the inlet of the pipe is led out from the outlet, the surface modification treatment is performed while passing through the pipe. Thus, by using the apparatus of the present invention, the surface modification of the fiber can be continuously performed.

  In the present invention, the operation timing of the heat source machine may be either (1) before the fluid flows into the pipe line or (2) after the fluid flows into the pipe line. In the case of (1), the fluid inflow machine causes a supercritical fluid or a subcritical fluid to flow into the pipe. In the case of (2), after the fluid inflow machine causes the fluid in the liquid state to flow into the inside of the pipe, it is changed to a supercritical fluid or a subcritical fluid by the heat source machine. Moreover, you may provide a heat source machine in both said (1) and (2). In this case, the fluid is made a supercritical fluid or a subcritical fluid before flowing into the pipe, and further maintained as a supercritical fluid or a subcritical fluid in the tube.

  In the present invention, the inlet that is the position where the fluid inflow machine allows the fluid to flow into the pipe line can be provided near the inlet or the outlet. One or two or more inlets can be provided. Moreover, it is preferable to provide the outflow port which a fluid flows out out of a pipe line in each of the inflow port side and the outflow port side of the inflow port with respect to one inflow port. The fiber inlet and outlet can also serve as the fluid outlet. When the pipes having substantially the same diameter over the entire length are used, one inflow port can be provided at a substantially intermediate position of the pipe.

  According to the present invention, the surface modification of fibers can be performed continuously and efficiently.

Next, embodiments of the present invention will be described in detail with reference to the drawings. However, the technical scope of the present invention is not limited by the following embodiments, and various changes can be made without changing the gist thereof. It can be carried out with modification. Further, the technical scope of the present invention extends to an equivalent range.
In the present invention, when water is used as the fluid, it can be carried out as follows.
First, water in the pipeline is set to a supercritical state or a subcritical state. At this time, the step of bringing the water into the supercritical state or the subcritical state may be performed either before or after water is introduced into the pipe. Since the critical point of water is a temperature of 374.4 ° C. and a pressure of 22.1 MPa, it is heated to about 300 ° C. to about 500 ° C., preferably about 300 ° C. to about 450 ° C., more preferably about 350 ° C. to about 450 ° C. The pressure is about 15 MPa to about 40 MPa, preferably about 20 MPa to about 35 MPa, and water is placed in a supercritical state or a subcritical state in the pipe.

  Next, in this state, the fiber is passed through the inside of the pipe line. When the fiber is a carbon fiber, the time (processing time) for the fiber to pass through the pipe line is preferably about 5 minutes to about 2 hours when supercritical water is used, and when subcritical water is used. Is preferably about 20 minutes to about 3 hours.

  In the high-temperature treatment as described above, carbon dioxide, methanol, ethanol or the like can be used as the fluid in addition to water. If an appropriate fluid is selected, the fibers can be processed while maintaining the temperature and pressure near the supercritical or subcritical state of the fluid. However, it is most preferable to select water as the fluid because it is easy to handle, low in cost, and rich in reactivity. In addition, there is no restriction | limiting in the form of the fiber processed, For example, it may be a short fiber or a continuous fiber. However, continuous fibers are preferred from the viewpoint of continuous treatment. Moreover, as a fiber, a carbon fiber is preferable.

Next, the present invention will be specifically described with reference to examples.
<Reactor>
FIG. 1 shows an outline of the reaction apparatus. This reaction apparatus is provided with four liquid feed pumps 1, a damper 2, a residual heat pipe 3, and pipe lines 4 a, 4 b and 5. The pipe line 4a connects between the liquid feed pump 1 and the damper 2, and the pipe line 4b connects between the damper 2 and the residual heat pipe 3, respectively. A pipe line 5 provided downstream of the residual heat pipe 3 (on the right side in FIG. 1) is spirally wound. The remaining heat pipe 3 and the pipe line 5 are immersed in the salt bath 6. An appropriate liquid (for example, KNO ₃ (45%) or NaNO ₃ (55%) can be used) is placed in the salt bath 6, and the internal temperature is about 150 ° C. to about 450 ° C. Can be set to an appropriate temperature. Since the critical point temperature of water, which is a fluid, is 374 ° C., it is possible to obtain an appropriate temperature condition across the critical point. Water, which is a fluid sent from the liquid feed pump 1, passes through the damper 2, flows through the residual heat pipe 3 and the pipe line 5, and is discharged from the outlet 7.

  As the liquid feed pump 1, two liquid chromatographic liquid feed pumps manufactured by JASCO Corporation and two liquid chromatographic liquid feed pumps manufactured by Shimadzu Corporation were used. Further, stainless pipes (material: SUS316, outer diameter: 1/16 inch, inner diameter: 0.25 mm) were used as the pipe lines 4a, 4b, and 5. Further, for the connection of the pipelines 4a, 4b, 5, JASCO made cheese (three-way) 1/16 inch was used. Stainless steel pipe (Material: SUS316, Outer diameter: 1 / 2inch, Wall thickness: 2.11mm, Length: 10cm) and Reducing union (Swagelok, Material: SUS316, Model number: SS) -810-6-1ZV-BL). The length of the pipe 4a was about 15 cm from the liquid chromatography pump 1 to the junction A, about 30 cm from the junction A to the junction B, and about 30 cm from the junction B to the damper 2. The length of the pipe 4b (from the damper 2 to the residual heat pipe 3) was about 1.5 m. The flow rate during the experiment was the total flow rate of 4 pumps. Moreover, when testing the pressure, the length and the pipe diameter of the pipe 5 after the preheat pipe 3 were changed.

<Preliminary experiment>
First, a test for confirming the relationship between the flow rate of water and the pressure between the liquid feed pump 1 and the residual heat pipe 3 was performed. A pipe line was not provided downstream of the residual heat pipe 3, and the test temperature was room temperature.
The results are shown in FIG. When the examination was conducted until the total flow rate reached 36 ml / min, it was confirmed that the pressure increased to 1.3 MPa. Furthermore, when a pressure gauge was inserted 5 cm from the outlet of the residual heat pipe 3 and the pressure in the pipe was measured, there was almost no difference between the liquid pump 1 and the pressure displayed on the pressure gauge. It was. Therefore, the reaction pressure during the experiment was determined by using the average value of the pressure displayed on each of the four pumps. Although the reaction pressure shown below includes the pressure obtained in this study as an error, the target pressure is about 30 MPa, so that an error of about 1 MPa is not a problem.

<Experiment to confirm the effect of temperature>
As the pipe 5, the relationship between the flow rate and pressure at various temperatures when the inner diameter of the pipe was 0.25 mm and the length of the pipe was 10 m was examined. As the temperature, 300 ° C., 350 ° C., 400 ° C., and 450 ° C. were used. The flow rate was in the range of 2 ml / min to 22 ml / min.
The results are shown in FIG. It was confirmed that the pressure increased as the flow rate increased under any temperature condition of 300 ° C to 450 ° C. As far as the critical pressure (22.1 MPa) or the critical temperature (374 ° C.) is exceeded, the relationship between the flow rate and the pressure is a linear relationship at any temperature condition.
Therefore, the relational expression was obtained only under the condition of the critical pressure (22.1 MPa) or more. When the relational expressions were y: pressure [MPa] and x: flow rate [ml / min], those shown in Table 1 below were obtained.

上記関係式より、圧力３０MPaを得るために必要な流量を各温度について求めたところ、下表２に示す流量が得られた。

From the above relational expression, when the flow rate required to obtain a pressure of 30 MPa was determined for each temperature, the flow rates shown in Table 2 below were obtained.

同様にして、圧力が２５MPa、３５MPa、及び４０MPaとなるために必要な流量を各温度について求めたものを図４に示した。

Similarly, what calculated | required the flow volume required for a pressure to become 25MPa, 35MPa, and 40MPa about each temperature was shown in FIG.

<Experiment to confirm the effect of pipe diameter>
As the pipe 5 (reaction tube), a 20 m long tube was used. The effect on the pressure when the inner diameter (0.25 mm and 0.5 mm) of the reaction tube was changed under the temperature conditions of 350 ° C. and 450 ° C. was examined.
The results are shown in FIG. Since the data above the critical pressure (22.1 MPa) was not obtained under the conditions of 350 ° C. and 0.5 mm, a relational expression between the flow rate and the pressure was obtained based on the data at 450 ° C. When the relational expressions were y: pressure [MPa] and x: flow rate [ml / min], the results shown in Table 3 below were obtained.

上記関係式より、圧力３０MPaを得るために必要な流量を各条件について求めたところ、下表４に示す流量が得られた。

From the above relational expression, when the flow rate required to obtain a pressure of 30 MPa was determined for each condition, the flow rates shown in Table 4 below were obtained.

同様にして、圧力が３５MPa、または４０MPaとなるために必要な流量を各条件について求めたものを図６に示した。

Similarly, what calculated | required the flow volume required in order that a pressure might be 35 MPa or 40 MPa about each condition was shown in FIG.

<Experiment to confirm the effect of tube length>
A SUS pipe having a diameter of 0.25 mm was used as the pipe line 5 (reaction pipe), and the influence on the pressure when the pipe length was changed to 5 m, 10 m, and 20 m under a temperature condition of 450 ° C. was examined. .
The results are shown in FIG. The relational expression between the flow rate and the pressure was obtained only under the condition of the critical pressure (22.1 MPa) or more. When the relational expressions were y: pressure [MPa] and x: flow rate [ml / min], the results shown in Table 5 below were obtained.

上記関係式より、圧力３０MPaを得るために必要な流量を各管長について求めたところ、下表６に示す流量が得られた。

From the above relational expression, the flow rate required to obtain a pressure of 30 MPa was obtained for each tube length, and the flow rates shown in Table 6 below were obtained.

同様にして、２５MPa、３０MPa、３５MPa、及び４０MPaとなるために必要な流量を各管長について求めたものを図８に示した。

Similarly, the flow rates required to reach 25 MPa, 30 MPa, 35 MPa, and 40 MPa for each tube length are shown in FIG.

<Conclusion>
As described above, according to the present embodiment, water, which is a fluid, is allowed to flow into the pipe, and the water can be brought into a supercritical state or a subcritical state. Thus, by passing the carbon fiber through the pipe line filled with supercritical water or subcritical water, the surface of the carbon fiber can be continuously modified.

<Carbon fiber surface modification device>
Next, using the above result, a carbon fiber surface modification apparatus as exemplified below can be provided.
Surface reformer-1
In FIG. 9, the outline | summary of the surface modification apparatus 10 was shown. The apparatus 10 is provided with a pipe line 11 provided with an introduction port 11A and a discharge port 11B for a carbon fiber CF, a fluid inflow machine 12 (pump) for flowing water into the pipe line 11, and a heat source unit 13. Yes. The heat source device 13 is provided between the fluid inflow device 12 and the pipe line 11. The water (supercritical water or subcritical water) that has passed through the heat source unit 13 flows into the inside of the pipe line 11 from the inlet 14 provided in the approximate center of the pipe line 11. In this apparatus 10, the carbon fiber CF inlet 11 </ b> A and outlet 11 </ b> B are configured to also serve as water outlets. A heat insulator 17 is wound around the pipe 11.

The carbon fiber CF is drawn out from the winder 15 on the left side of the drawing and wound by the winder 16 on the right side of the drawing.
According to this device 10, the water that has passed through the heat source device 13 by driving the fluid inflow device 12 is in a supercritical state or a subcritical state. This water flows from the inlet 14 into the pipe 11 and then flows out from the inlet 11A and outlet 11B. In this way, the surface of the carbon fiber CF is modified by allowing the carbon fiber CF to pass through the pipe 11 in which supercritical water or subcritical water is present. This method is superior in productivity because the carbon fiber CF can be continuously processed compared to the conventional batch system.
A heat source machine can be provided instead of the heat insulator 17.

Surface reformer-2
10 and 11 show an outline of the surface modification apparatus 20. The apparatus 20 is provided with a pipe 21 having an inlet 21A and a outlet 21B for carbon fiber CF, and a fluid inflow machine 29 (pump) for flowing water into the pipe 21. The pipe line 21 is configured by assembling a pair of upper and lower pipe line forming bodies 22 and 23. That is, a groove portion is recessed in the length direction at the center of the inner surface of the pipe formation bodies 22 and 23, and when the pipe formation bodies 22 and 23 are assembled, the both groove portions are aligned to form the pipe passage 21. It has come to be. In addition, a groove portion is formed in the inner surface of the pipe forming bodies 22 and 23 so as to form an inflow path 24 through which water flows into the center of the pipe 21.

  The pipe formation bodies 22 and 23 are made of a material having good thermal conductivity (for example, stainless steel or copper). In addition, a pair of heat source devices 25 and 26 are provided on the outer surfaces of the two pipe formation bodies 22 and 23, respectively. The water flowing into the pipe line 21 by driving the heat source devices 25 and 26 becomes supercritical water or subcritical water inside the pipe line 21. In this apparatus 20, the carbon fiber CF inlet 21A and outlet 21B are configured to also serve as supercritical water or subcritical water outlets. Further, the carbon fiber CF is unwound from the winder 27 on the left side of the drawing and is wound by the winder 28 on the right side of the drawing.

  In order to operate the apparatus 20, the pair of pipe forming bodies 22 and 23 are set to an operating position where they are assembled with each other, and the heat source units 25 and 26 are driven to preheat the pipe forming bodies 22 and 23. Here, when the fluid inflow machine 29 is driven, the water that has flowed in from the inflow path 24 (inlet) enters a supercritical state or a subcritical state inside the pipe line 21. This water flows out of the inlet 21A and the outlet 21B after passing through the inside of the pipe 21. In this way, the surface of the carbon fiber CF is modified by passing the carbon fiber CF through the pipe 21 in which supercritical water or subcritical water is present. This method is superior in productivity because the carbon fiber CF can be continuously processed compared to the conventional batch system.

It is the schematic of the reaction apparatus in a present Example. It is a graph which shows the relationship between the flow volume from a liquid feeding pump to the front of a preheat pipe, and a pressure. It is a graph which shows the relationship between the flow volume when changing temperature, and a pressure. It is a graph which shows the relationship between the flow volume required in order to obtain a predetermined pressure, and temperature. It is a graph which shows the relationship between the flow volume when changing the internal diameter of a pipe line, and a pressure. It is a graph which shows the relationship between the flow volume required in order to obtain a predetermined pressure, and a pipe internal diameter. It is a graph which shows the relationship between the flow volume and pressure when changing pipe length. It is a graph which shows the relationship between the flow volume required in order to obtain a predetermined pressure, and a pipe length. It is a figure which shows the structure of the surface modification apparatus-1. It is a perspective view which shows a mode when the pipe line formation body is open | released in the surface modification apparatus-2. In surface modification device-2, it is a perspective view showing a mode when a pipe line formation object is closed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,20 ... Surface reformer 11, 21 ... Pipe line 11A, 21A ... Inlet 11B, 21B ... Outlet 12, 29 ... Fluid inflow machine 13, 25, 26 ... Heat source machine 14, 24 ... Inlet CF ... Carbon Fiber (fiber)

Claims (4)

Line center provided an inlet of, in a condition in which the fluid flows from the inlet to the conduit is present as Oite supercritical fluid or subcritical fluid the fluid within the interior of the conduit, the conduit A method for modifying the surface of a fiber, wherein the fiber is allowed to pass inside. The fiber surface modification method according to claim 1, wherein the fluid is water. A pipe having a fiber inlet and outlet, a fluid inflow machine for flowing a fluid into the pipe , and a fluid which is provided at the center of the pipe and flows into the pipe A fiber surface reforming apparatus comprising: an inflow port; and a heat source device for bringing a fluid in the pipe line into a supercritical state or a subcritical state. 4. The fiber surface modification device according to claim 3, wherein the fluid is water.

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