JPS6357733A - Method and apparatus for producing fiber integrated body - Google Patents

Abstract

PURPOSE:To accelerate settling of oriented and bridged fibers without disturbing a liquid fiber suspension by the effect of gradient force and to improve the productivity of a fiber integrated body by imparting an intensity gradient in a vertical direction to the electric field between positive and negative electrodes. CONSTITUTION:The opposed spacing of the positive and negative electrodes 2a, 2b is gradually narrowed from the upper part thereof toward the lower part to form the electric field of the intensity gradient increasing from the upper part toward the lower part to the electric field. Anion and cation exchange membranes 3a, 3b are respectively perpendicularly provided to the inside of the electrodes 2a, 2b. The liquid fiber suspension prepd. by dispersing fibers such as whiskers into a dielectric liquid 9 such as CCl4 is injected into the above-mentioned electric field to orient the individual fibers in the liquid 9 in such a state in which the fibers are pointed at one end to the electrode 2a and at the other end to 2b. The fibers are simultaneously bridged and settled. The settling speed is additionally increased by the gradient force based on the intensity gradient of the above-mentioned electric field as compared to the settling speed by the gravity alone.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is suitable for use in the production of fiber aggregates and in the production of fiber-reinforced metals in which most of the wLN is one-dimensionally oriented. The present invention relates to a method and apparatus for producing a fiber aggregate.

[Prior Art] Conventionally, the following methods have been attempted in order to reduce the size of a fiber aggregate of relatively short fibers such as short T11 fibers or whiskers used in the production of fiber-reinforced metals.

One of them is a method using a centrifugal molding apparatus as shown in FIG. 2 (Japanese Patent Laid-Open No. 60-65200). In this centrifugal forming apparatus, fibers such as carbonized I↑ wire whiskers are supplied from a supply pipe 24 into a filtration membrane 25 in a porous cylindrical container 23 disposed in an outer cylinder 21, and the V&
This is a method of forming a hollow aggregate 26 of fibers. Note that 22 in the figure indicates a drain port.

Further, as another conventional method, as shown in FIG. 3, there is a method of orienting using a suction molding device.

In this method, a predetermined fiber mixture 34 is placed in the cylinder 31.
and pressurize the mixed liquid 34 using the pressurizing plunger 32 disposed at the top of the cylinder 31,
In this method, the filtrate is removed by vacuum suction from the filter medium 33 disposed at the bottom of the cylinder 31, thereby orienting and accumulating the fibers. In addition to these methods, there are methods such as paper making method and spray method.

However, in the fiber aggregate formed by the above method, especially the method using the above centrifugal molding device or suction molding device, many of the fibers are not one-dimensionally oriented but two-dimensionally or three-dimensionally oriented. be. Therefore, these methods have problems such as the fact that when the fiber aggregate is made into an IN-reinforced metal, the strength is not sufficiently strengthened in a predetermined one-dimensional direction, the fiber volume ratio is low, and the spring bag is large during compression molding. There are drawbacks.

Although there is a desire to obtain a fiber aggregate by orienting conventional fibers in a predetermined one-dimensional direction, most of the fibers cannot be obtained in one-dimensional orientation, and two-dimensional fiber aggregates cannot be obtained. Only oriented or three-dimensionally oriented fiber aggregates were obtained.

[Problems to be Solved by the Invention] In order to obtain the above-mentioned aggregate in which most of the fibers are one-dimensionally oriented, the present invention uses a fiber suspension in which short fibers, whiskers, and other fibers are dispersed in a dielectric liquid. , injected into an electric field created between positive and negative electrodes to electrostatically orient the fibers and simultaneously bridge them;
It is based on the technical idea that m-fibers with the same orientation are sequentially sedimented by gravity and accumulated.

However, there are a number of problems that arise when implementing this basic technology industrially (one of them is the problem of shortening the sedimentation time of the oriented 11 fibers).

Of course, as a general solution to the same problem, firstly, the fiber suspension is not simply allowed to settle by gravity, but the fiber suspension is more actively suctioned and discharged, and secondly, the electric field is increased to increase the strength of the fibers. Possible solutions include creating closer bridges between the two parties. However, active suction of the fiber suspension in the former case tends to cause mechanical disturbance of the liquid, and increasing the electric field strength in the latter case also causes proportional electrodynamic disturbance in the liquid. As a result, the orientation accuracy of the fibers is degraded by any means, thereby impairing the achievement of the original mission of the basic technology, which is the accumulation of -dimensionally oriented fibers.

The technical problem to be solved by the present invention is to accelerate the settling of oriented and bridged Ia fibers without causing disturbance in the fiber suspension.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides, in addition to the above basic technology, an intensity gradient to the electric field created between the positive and negative electrodes. A new structure is adopted in which the strength increases gradually from the upper part to the lower part.

When an electric field with an intensity gradient in the vertical direction is created in this way, the gradient force accelerates the sedimentation of the oriented bridging fibers without disturbing the fiber suspension.

In order to impart an intensity gradient to the above electric field, it is possible to divide the positive and negative electrodes into multiple sets in the vertical direction and apply different voltages to each set to change the strength of the electric field in stages. It is desirable that the facing distance be made narrower from the upper part toward the lower part, and the strength of the electric field created can be continuously changed.

A diaphragm is provided inside each of the positive and negative electrodes to prevent short-circuiting of the conductive am and to suppress turbulence of the fiber suspension, but the diaphragm is arranged vertically regardless of the inclined electrodes. be done. This is because if the diaphragm is placed parallel to the tilted electrode, the group of fibers bridged in the upper part of the diaphragm gap will interfere with the diaphragm, which becomes narrower as it sinks, causing the diaphragm to become narrower. This is because the terminal portion is bent.

The diaphragm is preferably an ion exchange membrane that prevents turbulence of the fiber suspension; in that case, an anion exchange membrane is placed inside the positive electrode, and a cation exchange membrane is placed inside the negative electrode. Placed. As a result, the anion exchange membrane prevents cations generated on the positive electrode side from permeating into the fiber orientation region, and similarly, the cation exchange membrane prevents anions generated on the negative electrode side from entering the fiber orientation region. In order to prevent permeation, ion-induced disturbances of the fiber suspension are effectively prevented.

The production of fiber aggregates begins with dispersing fibers such as staple fibers and whiskers in a dielectric liquid to form a fiber suspension.

As the above-mentioned fibers, all fibers that fall within the category of short fibers and whiskers can be used, and the diameter and length thereof are not particularly limited. The fibers may be made of any material that electrostatically aligns in the dielectric liquid when injected into a predetermined electric field as a fiber suspension, such as alumina, silica,
Alumina-silica, beryllia, carbon, silicon carbide, silicon nitride, glass, and various metals can be used.

Also applicable! It is also possible to use a mixture of two or more types of fibers.

The above-mentioned dielectric liquid refers to a liquid that exhibits dielectric properties upon application of voltage, and examples thereof include carbon tetrachloride, fluorochlorine-substituted hydrocarbons, n-hexane, and cyclohexane. Among these dielectric liquids, carbon tetrachloride is particularly preferred, and fluorochlorine-substituted hydrocarbons are superior in handling safety.

In order to disperse the fibers as uniformly as possible in the dielectric liquid, it is usually desirable to add a suitable amount of a surfactant, particularly a nonionic surfactant.

The fiber suspension was then injected into the electric field created between the positive and negative electrodes, directing the individual mM in the v4'm liquid with one end toward the positive electrode and the other end toward the negative electrode (-dimension). (orientation) state, and at the same time, precipitate it with bridging.

The strength of the electric field created by applying a voltage between the positive and negative electrodes is usually 0.5 to 5kv/cm, which is 0.2kv/cm.
If it is less than about /C11, the electrostatic orientation of the fibers will not be sufficient, and if it is more than about 1Qkv/cll, the fiber suspension will be disturbed and the precision of fiber orientation will deteriorate. The most preferred electric field strength is about 1-2 kv/cII. In addition,
The strength of the electric field is set to a preferable value depending on the type of fiber used, the dielectric properties of the dielectric liquid, the thickness of the fiber assembly to be produced, and the like. In the present invention, although the strength of the electric field between the positive and negative electrodes is different in the vertical direction, both are selected within the above range of strength. Many of the electrostatically oriented individual fibers are bridged in the direction of their orientation, increasing their mass, and their sedimentation is promoted more than floating fibers, but the gradient force based on the intensity gradient of the electric field reduces the sedimentation rate. further amplified.

The sedimented oriented fibers are accumulated on the inner bottom wall of the container, but the injection of the fiber suspension continues until the desired thickness is reached, and approximately the same amount of liquid is poured from the bottom wall of the container. Evacuation takes place. As mentioned at the beginning, it is important to be careful when discharging this liquid, and it is desirable to adjust the flow rate to such an extent that no mechanical turbulence occurs in the liquid, and then allow it to flow out naturally or by suction.

It is effective not only to adjust the flow rate but also to prevent leakage of fibers and turbulence of the liquid by discharging the flow through a filter arranged on the inner bottom surface of the container. For example, porous ceramic can be used.

After the accumulation is completed and the residual dielectric liquid is discharged and removed, the fiber aggregate is taken out and cut into a desired size and shape to form a fiber molded body for fiber-reinforced metal.

For carrying out the method of the present invention, for example, an apparatus as schematically shown in FIG. 1 is used. In the figure, 1 is a box-shaped container with an open top and a bottom so that the fiber suspension can be injected. Positive and negative electrodes 2a12b are attached, and the positive and negative electrodes 2a, 2b
On each inner side, negative and positive ion exchange membranes 3a and 3b are arranged vertically to define a fiber orientation region 4.

The bottom wall of the container 1 is provided with a drainage means consisting of a conduit 5 and a draining means that can be connected to a suction device (not shown), and on the inner bottom wall of the container 1 communicating with this, the fiber orientation area 4 is connected. A filter body 7 is installed over the entire area. Note that 8 is a voltage application device connected to the positive and negative electrodes 2a12b in order to create a predetermined electric field between the positive and negative electrodes 2a and 2b. The figure also shows a group of dark blue fibers 1○ which are electrostatically oriented and bridged in the dielectric liquid 9 after the fiber suspension is injected.
is the precipitate Q1, which shows the state in which it is sequentially accumulated on the filter body 7.

[Effects of the Invention] The method for producing a fiber aggregate of the present invention involves injecting a fiber suspension in which fibers are dispersed in a dielectric liquid into an electric field created between positive and negative electrodes, and electrostatically dissipating the fibers. When the liquid is caused to settle by bridging the orientation, the electric field is given an intensity gradient that becomes stronger as it goes from the upper part to the lower part, so the liquid is not disturbed by the action of the gradient force. By accelerating the sedimentation of the miscellaneous oriented bridges 1a, the productivity of the IN aggregate can be significantly improved.

Furthermore, in the fiber assembly manufacturing apparatus of the present invention, the interval between the opposing positive and negative electrodes is made narrower from the upper part toward the lower part, so that a constant voltage is applied between the positive and negative type peaks. A continuous intensity gradient can be imparted to the electric field by simply applying the electric field. Moreover, since it is a simple method of tilting the positive and negative electrodes, the effect of the gradient force can be maximized by adjusting the tilt.

[Example] Examples of the present invention will be described below.

Example 1 In the device shown in FIG.
were set to 56, respectively, and the alumina short fibers were suspended in a training liquid 9 made of fluorine-chlorine substituted hydrogen chloride 7: I
The fiber suspension is injected into the electrolyte created between the positive and negative electrodes 2a and 2b, the liquid level is set to 15c+a, and a gradient force is applied to the oriented bridging fibers while stopping the outflow of the liquid. was applied to promote sedimentation, and the sedimentation time until the fiber accumulation height h reached iQmm was measured. The strength of the above electrolysis is 1kV/Cm and 1.5kV/cm1 of the suspension. The thrust was tested under conditions of 59/m and 2.5 (1/m).

Example 2 ll! of the positive and negative electrodes 2a and 2b! i degree α is 10 each
The test was conducted under the same conditions as in Example 1 except that the value was set to 0.

Comparative Example A test was conducted under the same conditions as in Example 1, except that the positive and negative electrodes 2a12b were arranged vertically with an opposing interval of 1Qci, and the oriented bridging fibers were exclusively allowed to settle by gravity.

Table 1 shows the measurement results of the sedimentation times in Example 1.2 and Comparative Example.

Table 1

[Brief explanation of the drawing]

FIG. 1 is an explanatory sectional view showing one embodiment of the device of the present invention, and FIG.
The figure is a partially cutaway explanatory view showing a conventional centrifugal molding apparatus, and FIG. 3 is an explanatory view of the same conventional suction molding apparatus. 1... Container 2a... Positive electrode 2b... Negative electrode 3a... Anion exchange membrane 3b... Cation exchange membrane 4... Fiber orientation region 7... Filter body 8...
Voltage application device 9...Dielectric liquid 10...Fiber group patent applicant Toyoda Jisuke Oriiso Seisakusho Co., Ltd. agent
Patent attorney Hirodo Okawa Patent attorney Akio Maruyama Figure 1 Figure 2 Figure 3 Vacuum C81

Claims (3)

[Claims] (1) A fiber suspension in which short fibers, whiskers, and other fibers are dispersed in a dielectric liquid is injected into an electric field created between positive and negative electrodes to electrostatically orient the fibers and simultaneously bridge them; A method for producing a fiber assembly in which the same oriented fibers are accumulated by gravity sedimentation, wherein the electric field becomes stronger from the upper part to the lower part between the positive and negative electrodes. manufacturing method. (2) An upper open container, positive and negative electrodes supported by the inner wall of the container and facing each other, and whose opposing distance becomes narrower from the upper part to the lower part; and negative and positive ion exchange membranes arranged substantially vertically inside each of the negative electrodes, a drainage means provided on the bottom wall of the container, and a voltage application device connected to both the electrodes. A manufacturing device for a fiber aggregate consisting of. (3) The device according to claim 2, wherein a filter is installed on the inner bottom surface of the container.