JPS6392767A - Production of fiber aggregate - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a method for producing a fiber aggregate, and more specifically, a fiber aggregate in which most of the fibers are one-dimensionally oriented, which is particularly suitable for use in producing fiber-reinforced metals. Concerning a method of manufacturing a body.

[Prior Art] Conventionally, in order to obtain an aggregate of relatively short fibers such as M fibers or whiskers used in the production of fiber-reinforced metals, a fiber dispersion liquid is supplied into a porous cylinder lined with a filtration membrane, for example. A centrifugal molding method (Japanese Unexamined Patent Publication No. 60-652
00) and a suction molding method in which a plunger pressurizes a 11-fiber dispersion liquid supplied into a cylinder, and the filtrate is actively discharged from the bottom of the cylinder through a filter material.

However, in the m111 aggregate obtained by the above-mentioned forming method, most of the Il miscellaneous materials are oriented in three-dimensional directions, and the volume fraction of fibers is low. In the case of suppression, very unsatisfactory results were obtained.

[Problems to be Solved by the Invention] In order to obtain a fiber N aggregate in which many of the fibers are one-dimensionally oriented, the present invention provides a method for dispersing a fiber suspension in which fibers are dispersed in a dielectric liquid between positive and negative electrodes. It is based on the technical idea that the $IN is injected into a generated electric field to electrostatically orient it and at the same time bridge it, causing the oriented fibers to sediment and accumulate one after another.

In order to prevent the flow of cations and anions generated on the positive and negative electrode sides by charge injection from causing convection in the fiber suspension, anions are placed inside the positive electrode. Exchange! km, and a cation exchange membrane is arranged in parallel inside the negative electrode to prevent the generated ions from penetrating into the fiber orientation region.

However, when the electrostatic orientation of m-fibers is continued for a long time, as the generated ions multiply and accumulate, a small portion of the permeated ions that cross the ion exchange membrane and enter the m-fiber orientation region also increase proportionally. As a result, the convection of the fiber suspension caused by the flow of the permeated ions causes disturbance in the orientation of the fibers.

The present invention aims to solve the technical problem of suppressing the amount of the above-mentioned permeating ions to a completely or irresponsibly low level and ensuring highly accurate orientation of electrostatically oriented fibers.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention, in addition to the above-mentioned basic technology, includes an ion-exchange membrane arranged inside each of the positive and negative electrodes, and a space between the ion-exchange membrane and the facing electrode. A novel configuration is adopted in which a flow of dielectric liquid is created in the boundary area independent of the above II miscellaneous suspension.

When an independent dielectric liquid flow is formed in the boundary area between the ion exchange membrane and the facing electrode in this way, the cations and anions generated on the positive and negative electrode sides flow into #j formation in the boundary area between the ion exchange membrane and the facing electrode. The ions passing through the ion-exchange membrane are negligible and are reduced to a negligible amount because they are not accumulated by the flow of the dielectric liquid (they are sequentially flowed out and eliminated), and the convection of the fiber suspension, that is, the orientation of the m-fibers, is reduced. Disturbing factors are completely eliminated, and most of the fibers in the suspension are electrostatically oriented in one dimension with high precision without any disturbance.

The production of fibers [1M bodies begins with dispersing fibers such as short fibers and whiskers in a dielectric liquid to form a fiber suspension.

As the above-mentioned 11M, anything that falls within the category of short fibers and whiskers can be used, and its diameter and length are not particularly limited. Applicable I! The miscellaneous material may be any material that electrostatically aligns in the electric liquid when injected as a fiber suspension into a predetermined electric field, such as alumina, silica, alumina-silica, beryllia, carbon, In addition to silicon carbide, silicon nitride, glass, various metals, etc. can be used.

Moreover, two or more types of these fibers can also be used in combination.

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 generally desirable to add an appropriate amount of a surfactant, particularly a nonionic surfactant.

Next, the above fiber suspension is injected into the electric field created between the positive and negative fi electrodes, and the individual fibers are separated in the dielectric liquid with one end being positive. f! The method is to orient the electrodes so that the other end is directed toward the negative electrode (-dimensional orientation), and at the same time, to cause the electrodes to settle with bridging.

The strength of the electric field created by applying a voltage between the positive and negative electrodes is usually 0.5 to 5 kv/cm, and 4 is 0.2 kv/cm.
If the electrostatic orientation of the fibers is less than about 1 cm, the electrostatic orientation of the fibers is insufficient (and 1
When the flow rate exceeds about 0 kv/am, disturbance occurs in the Jl miscellaneous suspension, and the fiber orientation accuracy deteriorates. The most preferred electric field strength is about 1-2 kv/cm. Note that the strength of the electric field is set to a preferable value depending on the type of fibers used, the dielectric properties of the dielectric liquid, the thickness of the fiber assembly to be manufactured, and the like.

In addition, in the present invention, the above l! When the 4B strips in the fiber suspension are electrostatically oriented and bridged and allowed to settle, the l! By creating a continuous or intermittent flow of the training liquid independent of the miscellaneous suspension, the ions generated on the positive and negative electrode sides are discharged and eliminated without being accumulated, and the ion exchange is performed. Ions that permeate the membrane and enter the fiber orientation region are restricted to almost nothing, so there is no convection of the m-thread suspension due to ion flow! a
The particles are stably electrostatically oriented.

The sedimented oriented fibers are accumulated on the inner bottom wall of the container, but until the desired thickness is reached, the injection of the fiber suspension is continued, and an approximately equal amount is deposited from the bottom wall of the container. The liquid is drained. In this case, it is important to be careful when draining the liquid.
It is desirable to adjust the flow rate to such an extent that no mechanical disturbance occurs to the liquid, and then allow it to flow out naturally or be discharged by suction.

It is effective to discharge the above-mentioned flow through a filter arranged on the inner bottom surface of the container, not only to reduce the flow rate FAw but also to prevent leakage of mtIi and disturbance of the liquid. 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-reinforced metal fiber molded body.

For carrying out the method of the invention, an apparatus as schematically shown in the figure is used. In the figure, reference numeral 1 denotes a box-shaped container made of a non-conductive material and with an open bottom so that a fiber suspension can be injected.
A N electrode 2.3 is attached, an anion exchange membrane 4 is installed inside the positive electrode 2, and a cation exchange membrane 15 is installed inside the negative N electrode 3.
are arranged side by side. The ion exchange 1! i14.
5 prevents short-circuiting of the conductive fibers and at the same time defines a JaH orientation region 6, and furthermore, cations generated on the positive electrode 2 side and anions generated on the negative electrode 3 side permeate into the miscellaneous orientation region 6. It prevents The container 1 is provided with a passage 8.8 for creating an independent dielectric liquid flow in each boundary area 7.7 between the ion exchange membrane 4.5 and the facing electrode 2.3. .8 is such that when the dielectric liquid in the interstitial boundary area 7.7 is continuously or intermittently discharged via the lower discharge part F3a, 8a, new dielectric liquid in the same amount as this is discharged from the upper supply part 8b. , 8b.

Of course, it is also possible to provide a circulation system in which the dielectric liquid discharged from the discharge section F3a1f3a is returned to the supply sections 8b, 8b through an ion removal process.

The bottom wall of the container 1 is provided with drainage means consisting of a conduit 9 and a cock 10, which can be connected to a suction device, for example, and on the inner bottom wall of the container 1 that communicates with this drain means (see above 1! miscellaneous orientation area). The filter body 1 made of ceramic, for example, over the entire area of 6
1 is installed. Note that 12 is a voltage application device connected to the positive and negative electrodes 2.3 in order to create a predetermined electric field between the positive and negative electrodes 2.3. The figure also shows a state in which, after the miscellaneous suspension is injected, the 418f groups 13 that are electrostatically aligned and bridged in the dielectric liquid settle and are sequentially accumulated on the filter body 13. It is something.

[Effect of the invention 1] 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 When the fibers are aligned and bridged and sedimented, a dielectric liquid flow fg1 independent of the fiber T4 suspension is formed in the boundary region between the ion exchange membrane that defines the fiber orientation region and the opposing electrode. Since the ions generated on each electrode side are discharged and eliminated without being released, the ions that pass through the ion exchange membrane and enter the fiber orientation area are limited to almost no tIII. There is no convection of the fiber suspension caused by the flow of ions, and therefore it is possible to produce fiber aggregates with extremely good orientation even when using short HrN or even minute whiskers.

Furthermore, since an aggregate having a higher m-male volume fraction is produced in conjunction with such improvement in fiber orientation, a fiber-reinforced metal with significantly higher strength can be manufactured using the aggregate.

〔Example) The present invention will be explained below with reference to Examples.

Experimental Example 1 In the apparatus shown in Fig. 1, the height of the liquid level in the container of the dielectric liquid containing a nonionic surfactant of 2Cj or less was set at 15CI11, and the distance between the positive and negative electrodes was set to 15CI11, and the distance between the positive and negative electrodes was set to 15CI11. 15cc of independent dielectric liquid in the interspace region
While continuing to flow at a flow rate of in, a voltage of 2 to 2 was applied between the positive and negative electrodes, and after IOHr had elapsed, a miscellaneous suspension in which fibers with a fiber concentration of 5 g/l were dispersed in the dielectric liquid was injected. While gradually increasing the applied voltage, the voltage value at which sI & miscellaneous disturbance was visually recognized was measured.

Experimental Example 2 The voltage value when fiber disturbance was recognized was measured under the same conditions as Experimental Example 1 except that the initial applied voltage was 10 kV.

Comparative Example 1 The voltage value when fiber disturbance was recognized was measured under the same conditions as Experimental Example 1, except that an independent dielectric liquid was not flowed into each interface between the ion exchange membrane and the facing electrode. .

Comparative Example 2 The voltage value at which 4aH disturbance was recognized was measured under the same conditions as Comparative Example 1 except that the initial applied voltage was 10 kV.

Table 1 shows the measured voltage values of Experimental Example 1.2 and Comparative Example 1.2.

Table 1

BRIEF DESCRIPTION OF THE DRAWINGS The figure is a sectional view schematically showing an apparatus for implementing the present invention. 1... Container 2... Positive electrode 3... Negative charge 8i 4... Gap ion exchange membrane 6... Cation exchange 1! 6... Fiber orientation region 7... Sandwich boundary region
6... Passage 11... Filter body 12... Voltage application device 13... Fiber group

Claims (1)

[Claims] A fiber suspension in which 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, causing the oriented fibers to sediment and accumulate one after another. In the method for producing a fiber aggregate, an ion exchange membrane is arranged in parallel inside each of the positive and negative electrodes, and an ion exchange membrane is provided in a boundary region between the ion exchange membrane and the opposing electrode, independent of the fiber suspension. A method for producing a fiber aggregate, characterized by creating a flow of a dielectric liquid.