JPH04343746A - Production of sheet-formed aggregate of short fiber - Google Patents

Abstract

PURPOSE:To provide a process for the production of a sheet-formed aggregate of short fibers uniformly dispersed and accumulated in all directions of the sheet, i.e., in the directions of length, width and thickness. CONSTITUTION:Three or more filament bundles are supplied in a state arranged in parallel with essentially equal distances. The bundles are cut and dispersed in the form of short fibers, which are successively collected on a collection face.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a sheet-like short fiber aggregate. More specifically, a uniform raw material is supplied and cut at a uniform density, the cut fibers are dispersed without excessive accumulation, and collected over a short distance, and the accumulation state of the short fibers is adjusted to the width of the sheet. The present invention relates to a method for producing a sheet-like short fiber aggregate that is uniform in both direction and length and has excellent uniformity of texture.

0002

[Prior Art] All conventional methods for obtaining sheet-like short fiber aggregates start from a short fiber mass prepared in advance and disperse it to form a sheet, so the amount of supply cannot be kept constant. Therefore, it is extremely difficult in principle to obtain a uniform sheet.

0003

SUMMARY OF THE INVENTION It is an object of the present invention to provide a manufacturing method for obtaining a sheet-like short fiber aggregate in which short fibers are uniformly dispersed throughout.

0004

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention employs the following means.

That is, the method for producing a sheet-like short fiber aggregate of the present invention involves supplying a plurality or more long fiber bundles while arranging them at substantially equal intervals, cutting the fiber bundles, and dispersing them into short fibers. The method is characterized in that the fibers are then sequentially collected on a collecting surface.

[0006]

[Function] The fineness of one long fiber bundle, which is the starting material of the present invention, is in the range of 50 to 50,000 deniers. Less than 50 deniers is a problem in terms of productivity, while a fineness exceeding 50,000 deniers is poor in cuttability. It is not desirable because it has a bad influence.

[0007] In order to arrange the long fiber bundles at substantially equal intervals, it is preferable to use a guide member such as a comb-shaped, eyeball-shaped, grooved, partition plate, or the like.

[0008] These guide members act on the short fibers so as to ensure uniformity in the state of accumulation of the short fibers in the longitudinal direction and the width direction of the sheet.

Next, the fiber bundle is cut by a cutting device, and a combing roller is used as the cutting device to cut the fiber bundle without accumulating the cut fibers and with an opening action. It is particularly preferable in terms of being discharged to the outside. The long fiber bundle supplied to the combing roller is preferably a rigid but brittle fiber, and carbon fiber (including graphite fiber) is a suitable material, for example.

[0010] Next, the cut short fibers discharged outside the cutting system are separated by a distance ι between the long fiber bundles arranged at equal intervals.
, if the bundle arrangement width is ι', then the distance L from the cutting point of the cutting device to the collection surface is set to be greater than or equal to ι and less than or equal to ι', thereby making the supply linear density of the fiber bundles more uniform. This is preferable because it acts in the direction of In other words, this further improves the uniformity of the short fiber accumulation state in the sheet width direction. Furthermore, it has an extremely effective effect on the uniformity of the formation, which is particularly important for sheets.

[0011] The present invention maintains a uniform short fiber accumulation state by supplying long fiber bundles arranged at equal intervals as described above, and collecting short fibers after cutting within a specific distance. I was able to do that. More preferably, the collection width is approximately the same as the supply width of the long fiber bundle (long fiber bundle arrangement width: ι'). If the collection width is either larger or smaller than the supply width, it will be difficult to achieve uniform collection performance. More specifically, the collection width can be determined as follows.

That is, the number of long fiber bundles is n, the collection width is W, and the distance between the fiber bundles where the long fiber bundles are arranged at equal intervals is ι.
Assuming the fiber bundle arrangement width ι', ι'=(n-1)ι Therefore, W=n・ι=(ι'+ι) The preferable collection width range is 0.5(ι'+ι)<W<2.0(ι'+ι) More preferably 0.8(ι'+ι)<W<1.2(ι'+ι) Most preferably W=(ι'+ι).

When the collection width is smaller than the above range, secondary aggregation tends to occur in the dispersion area of short fibers in addition to the fact that the basis weight of the sheet edge increases. The basis weight near the area decreases, making it difficult to form a sheet that is uniform in the width direction. In addition, when collecting, it is preferable to provide side walls near both ears, since this can alleviate problems near the ears.

[0014] Furthermore, when accumulating short fibers by the above method, the feeding speed of the long fiber bundle and the traveling speed of the collection surface are each constant, and furthermore, a system in which these speeds are operated in conjunction with each other is provided. It is preferable to employ this method in order to ensure the uniformity of the obtained sheet.

Next, the method for producing the sheet-like short fiber aggregate of the present invention will be explained with reference to the drawings. FIG. 1 is a diagram showing an embodiment of obtaining a sheet-like short fiber aggregate of the present invention. After passing through a separate guide 2 for arranging (distance ι') and a feed device 3, the short fibers are fed to a cutting device 4, where they are cut to obtain short fibers 5.

The feed device 3 may be any device such as a roller and a plate, a roller and a roller, or an apron roller and an apron roller.

In FIG. 1, point C of the housing 4' is the cutting position.

The cut short fibers 5 are dispersed in the chamber 6 and collected by a collection net 7 running at a distance (L) of ι or more and ι' or less from the cutting position (from point C), The short fibers are accumulated one after another to obtain a sheet-like short fiber aggregate 8. 9, 10
indicates the drive device for the collection net.

FIG. 2 shows a state in which the long fiber bundles 1 of FIG. 1 are arranged at equal intervals (distance ι) (distance ι') and are supplied to the feed device 3 and the cutting device 4.

In the figure, X-X' indicates the axial direction of the cutting device 4. There may be a plurality of long fiber bundles 1 arranged at equal intervals, and by doing so, high productivity can be obtained.

[0021]

【Example】

Example 1 Single yarn denier is 0.6 denier, number of constituent fibers is 3000
2 book polyacrylonitrile (PAN) carbon fiber bundles
Prepare 01 pieces, arrange them at intervals of ι=5mm, and make ι'=10
00 mm, L = 400 mm, and collected with a collection width of 1020 mm. As the starting material was a long fiber bundle with a uniform thickness, the sheet was uniform in the longitudinal direction. The fiber bundles are arranged at equal intervals in the width direction of the sheet, so uniformity in the width direction of the sheet is obtained, and the sheet is highly uniform in texture because it is dispersed into short fibers. A short fiber aggregate was obtained.

Example 2 Single yarn denier is 0.6 denier, number of constituent fibers is 2400
Prepare 21 PAN-based carbon fiber bundles, ι = 50m
Arranged at intervals of m, 5 systems are provided that are the same as the system that supplies the cutting device with ι' = 1000 mm, and the collection distance L = 200 mm.
When collected on a collection net with a collection width of 1050 mm, it was found that the uniformity in the longitudinal direction was extremely good because the starting material was a long fiber bundle with a uniform thickness, and the fiber bundle was collected evenly. Since the sheets were arranged at intervals, good uniformity in the width direction of the sheet was obtained. Furthermore, since the particles were dispersed into short fibers, a sheet-like short fiber aggregate with extremely uniform texture was obtained.

[0023]

[Effects of the Invention] By using long fiber bundles of uniform thickness as the starting material, arranging the fiber bundles at substantially equal intervals, and dispersing them into short fibers, (1) Uniformity of the short fiber accumulation state (
2) Uniformity of the short fiber accumulation state in the sheet width direction (3)
It exhibits excellent performance with uniform formation, and can be suitably used, for example, as a precursor for carbon-carbon (C/c) composites, which are fuel cell electrode base materials, and as a precursor for various composite materials. It is effective as a base material in applications that require extremely high precision, performance, and reliability.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing one embodiment of obtaining a sheet-like short fiber aggregate of the present invention.

FIG. 2 is a plan view showing a state in which long fiber bundles are arranged at regular intervals in the embodiment diagram of FIG. 1;

[Explanation of symbols]

1: Multiple long fiber bundles 2: Separate guide 3: Feed device 4: Cutting device 4': Housing 5: Short fiber 6: Chamber 7: Collection net 8: Collection net drive device 9: Collection net drive device ι: Distance between long fiber bundles ι′: Long fiber arrangement width c: Cutting point of long fiber bundle L: Collection distance

Claims (5)

[Claims] 1. Supplying a plurality of long fiber bundles arranged at substantially equal intervals, cutting the fiber bundles and dispersing them into short fibers, and then sequentially collecting the short fibers on a collection surface. A method for producing a sheet-like short fiber aggregate, characterized in that: 2. Collecting the cut short fibers on a collection surface running at a distance from the cutting position of the long fiber bundle to a distance greater than or equal to the inter-fiber bundle distance and less than or equal to the fiber bundle arrangement width. The method for producing a sheet-like short fiber aggregate according to claim 1. 3. The method for producing a sheet-like short fiber aggregate according to claim 1, wherein the feeding speed of the long fiber bundle and the traveling speed of the collection surface are linked. 4. The method for producing a sheet-like short fiber aggregate according to claim 1, wherein the long fiber bundle is carbon fiber. 5. The method for producing a sheet-like short fiber aggregate according to claim 1, wherein the means for cutting the fiber bundle is a combing roller.