JPH0458783B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a mat of conductive fibers such as metal-coated glass fibers and a method for manufacturing the same.
Specifically, in conductive fiber mats, which are made into a long pine-like shape by overlapping and splicing the ends of spread cotton sheets, the density unevenness of the conductive fibers at the overlapped portion is eliminated, and the electromagnetic wave shielding properties are made even. The present invention relates to the mat, which has been improved so as to improve the mat, and a method for manufacturing the same.

[Prior Art] In recent years, as electronic devices have developed and become more widespread, a method of embedding conductive fiber mats in plastic is becoming popular in order to prevent electronic devices from being influenced by electromagnetic waves emitted by the devices.
In addition, conductive fibers have also come to be used in parabolic antennas made of FRP.

As one of the manufacturing methods of this conductive fiber mat,
There is a method in which rolled cotton sheets produced by the cotton rolling method are spliced together to form mats.

First, with reference to FIGS. 2 and 3, a method for manufacturing a conductive glass fiber sheet by a cotton spreading method will be described.

In FIG. 2, reference numeral 10 denotes a glass melting tank for melting glass 12, and a plurality of spinning nozzles 14 from which molten glass flows out are provided at the bottom of the tank so as to be arranged in a straight line at predetermined intervals.

Below the melting tank 10, there is a rotating drum 18 for winding up the glass fibers 16 hanging down from the nozzle 14, a drive device for rotating the rotating drum 18, and a rotating drum 18 in the axial direction (perpendicular to the plane of the paper).
A winding device having a drive device (both not shown) for reciprocating the winding device is installed. Further, a molten metal holding furnace 2 for applying a metal coating to the glass fiber 16 is located between the winding device and the melting tank 10.
0 is set. This molten metal holding furnace 20
is provided with an opening 22 on its side, and a coating nozzle 24 is attached so as to cover this opening 22, and the glass fiber 16 can pass through the bulge of molten metal that bulges out from the tip of this nozzle 24. It is configured as follows.

The drum 18 or the molten metal holding furnace 20 can be shifted in the left and right directions in the figure, so that the glass fiber 16 can be moved to the nozzle 24 only at a desired time.
It is designed to be able to pass through the molten metal bulge at the tip.

In the manufacturing apparatus configured in this way, the molten glass 12 in the melting tank 10 flows down from the nozzle 14, is stretched by the drum 18, and is stretched.
The fibers are turned into thin fibers and wound onto the drum 18. At this time, since the drum 18 is reciprocating in its axial direction (direction perpendicular to the paper surface in the figure), each glass fiber 16 is wound up in a meandering wave-like manner.

When the layered bundle of glass fibers 26 wound around the rotating drum 18 reaches a predetermined thickness, the rotation of the drum 18 is stopped and the layered bundle of glass fibers 26 is cut in the axial direction of the nozzle 18. drum 1
Remove from 8. As shown in FIG. 3, the removed bundle 26 is expanded while being stretched in a direction perpendicular or almost perpendicular to the glass fibers (this operation of expanding while being stretched is called spreading).
This becomes a spread sheet 28 of glass fiber.

That is, in FIG. 3, when the glass fiber layered bundle 26 removed from the drum 18 is rolled up from one end onto another rotating drum 30, it is wound up into a sheet on the other rotating drum 30. It will be done. The rolled cotton sheet 28 completed in this way
is a structure in which layers of glass fibers extending in one direction and layers of fibers extending in a direction crossing this are alternately laminated.

In the manufacturing process using this cotton rolling method, a large number of parallel glass fibers 16 are wound around a drum 18 that reciprocates in the axial direction, so as shown in FIG. has an inclined portion 26a on the end side in the drum axis direction. Therefore, this was cut in the axial direction and stretched out (in Fig. 4, the broken line a indicates this cutting line, and the arrow b indicates the direction of stretching).
In this case, as shown in FIG. 5, inclined portions 26a are also formed on both ends of the spread bundle 26.

This bundle is rolled in a direction perpendicular or almost perpendicular to the extending direction of the fibers, as shown by arrow A in FIG. Similarly, the rolled cotton sheet 28 obtained by rolling this cotton gradually becomes thinner at both end sides in the rolling direction. Reference numeral 28a in FIG. 6 indicates this thin portion.

[Problems to be Solved by the Invention] As shown in FIG. 7, this rolled cotton sheet 28 is made by overlapping and splicing both ends in the rolling direction to form a long mat, which is usually wound into a roll 32 shape. Take it and make it into a product.

However, conventionally, the inclined part L of the bundle 26 is wound up to a length of about 15 mm, which is the length of the thin part shown in FIG.
The cotton is spread so that L' is approximately 3 m, and in such conventional products, the fiber density in the overlapped parts of the spread cotton sheets 28 is uneven, and the electromagnetic wave shielding performance of the resulting mat also varies considerably. Sometimes this occurred.

[Means and effects for solving the problems] The present invention provides a mat made by overlapping spread sheets of conductive fibers with their end sides stacked together to form a mat, in which the thin part of each spread cotton sheet is ~30m,
These thin parts are overlapped and joined together.

Furthermore, the method for producing conductive fiber mat of the present invention includes:
The length of the inclined part of the bundle wound on the rotating drum
20 to 150 mm, and the thin part of the expanded cotton sheet is 5 to 30 m.
The bundle is spread so that the cotton bundle is spread, and then the thin parts of the obtained spread cotton sheets are overlapped and spliced to form a mat.

According to the present invention, there is little variation in the fibers in the thin section of the spread cotton sheets, and there is also little variation in the fiber distribution at the seam portion of the mat in which the spread cotton sheets are stacked. This also eliminates variations in electromagnetic wave shielding performance.

The present invention will be explained in detail below.

In addition to metal-coated glass fibers, carbon fibers and metal fibers can also be used as the conductive fibers used in the present invention, but metal-coated glass fibers are preferable in terms of cost, mass production, lightness, durability, etc. suitable.

The diameter and material of this glass fiber are not particularly limited, but it is preferable to have a diameter of about several μm to 30 μm. The material may be either alkali-free glass or alkali glass, and various compositions conventionally used for glass fibers, such as E glass, C glass, and A glass, can be used.

The metal for coating the glass fibers is preferably one that has a low melting temperature, is easy to coat, and has good corrosion resistance. For example, aluminum or an aluminum alloy is suitable. Other materials used include copper, zinc, and silver. If the amount of metal coating is too small, conductivity cannot be ensured, and if it is too large, the flexibility of the fibers will be reduced and costs will increase. When using aluminum, it is about 5 to 200% of the weight of glass fiber per unit length of fiber, especially
It is preferably about 20 to 100%.

Note that the spacing in the sheet surface direction of the spread sheet of conductive fibers changes depending on the frequency of the electromagnetic waves.

Therefore, in the present invention, the bundle is wound so that the inclined part (dimension L in Fig. 5) is 20 to 150 mm, and the length of the thin part of the spread cotton sheet (L' in Fig. 6) is 20 to 150 mm. Spread the cotton to a length of 5 to 30 meters. By setting the length of the inclined part and the thin part,
The fiber density distribution unevenness in the sheet joining portion where the thin portions are overlapped is extremely small. Note that if the dimensions L and L' both deviate from the above ranges, the density distribution at the joint portion will become more uneven. The reason for this increase in unevenness is presumed to be that uneven forces tend to be applied to the fibers when the degree of stretching during cotton spreading is too high or too low.

The rolled cotton sheets obtained by rolling cotton are spliced by overlapping the thin end parts of the sheets, and are usually rolled up into a roll. The spread cotton sheets can be bonded to each other by distributing the binder in a shower-like manner, then removing the excess liquid by suction, and then heat-treating the binder. In addition to starch-based binders, various binders such as those based on thermosetting synthetic resins such as phenolic resin and vinyl acetate can be used.

In addition, in the present invention, the overlapping length of spread cotton sheets is L x t/t' x W/
It is preferable to set the length to be calculated by W′.
However, in the formula, L is the width of the sloped part of the bundle, t is the basis weight of the non-slanted part of the bundle, W is the length of the bundle in the fiber direction,
t′ is the basis weight of the non-thin part of the spread cotton sheet, and W′ is the length of the spread cotton sheet in the direction orthogonal to the spreading direction.

[Example] Examples will be described below.

Using the apparatus shown in FIG. 2, glass fibers were coated with aluminum to produce aluminum-coated glass fibers. First, from the glass melting tank 10 in which 30 chips 14 are arranged on the bottom, 30 chips 14 with a width of 160 mm are
The glass fibers of the book are pulled out in parallel, and the bulges of molten metal are brought into contact with them to coat them with aluminum.
Then, this aluminum-coated glass fiber is continuously wound around a drum 18 that is reciprocated in the axial direction with a stroke width of 75 mm. After the aluminum-coated glass fiber layer is wound around the drum 18 until it reaches a basis weight t=7860 g/m ² , the drum 18 is stopped, and the bundle 26 is then cut in the drum axis direction and removed from the drum 18 . The glass fiber diameter is approximately 15μm.
It is. Furthermore, the amount of aluminum deposited is 67% of the weight of the glass fiber.

The bundle cut from the drum was wound up on a roll 30 and spread as shown in FIG. Note that the thin part
The cotton was rolled out so that the length L' was 12.8 m and the length M' of the non-thin part was 14.5 m, for a total of 40.1 m. As shown in FIG. 7, the thin-walled parts of the bundles were overlapped one after another while being rolled to form a roll with a total length of 200 m, and a vinyl acetate-based binder was applied to the rolled cotton from above the sheet.

Comparative example: The length L of the sloped part of the bundle was 15 mm, the length M of the non-slanted part of the bundle was 145 mm, the length L' of the thin part of the spread cotton sheet was 3 m, and the length M' of the non-thin part was 34 m. Except for this, a conductive glass fiber mat was produced in the same manner as in the above example.

When the variation in the basis weight (g/m ² ) of the conductive glass fiber mats obtained in these Examples and Comparative Examples was measured, the results shown in FIG. 1 were obtained.

According to FIG. 1, it is clear that the present invention has extremely small unevenness in the fabric weight of the seams. The standard deviation of the basis weight distribution for the product of the present invention was 8, while it was 18 for the comparative example product.

[Effects of the Invention] As detailed above, according to the present invention, the unevenness of the fiber density distribution at the joint portion between spread cotton sheets is extremely small. Further, since the electromagnetic wave shielding effect is proportional to the pine area weight under the condition that the metal deposition rate is constant, a conductive fiber mat with extremely small unevenness in the electromagnetic wave shielding effect is provided.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the measurement results of the pine area weight of the products of the present invention and comparative examples. Figures 2 and 3 are cross-sectional views and perspective views illustrating the manufacturing method of glass fiber sheets by the cotton rolling method, and Figures 4, 5, and 6 are dimensional changes of the fiber bundle in the cotton rolling method, respectively. FIG. 7 is a side view illustrating a method of joining spread cotton sheets. 10...Glass melting tank, 14...Spinning nozzle,
18...Rotating drum, 26...Bundle, 26a...
Inclined portion, 28... expanded cotton sheet, 28a... thin walled portion.

Claims (1)

[Scope of Claims] 1. A conductive fiber made by joining a spread cotton sheet in the longitudinal direction in which conductive fiber layers extending in one direction and conductive fiber layers extending in a direction crossing this are alternately laminated. 1. A conductive fiber mat characterized in that a thin walled portion on the longitudinal end side of a rolled cotton sheet is 5 to 30 m long, and the thin walled portions of adjacent rolled cotton sheets are overlapped and joined together. 2. The conductive fiber mat according to claim 1, wherein the conductive fiber mat is wound into a roll. 3. The conductive fiber mat according to claim 1 or 2, wherein the conductive fibers are metal-coated glass fibers. 4. Winding a large number of parallel conductive fibers onto a rotating drum that reciprocates in the axial direction, and stopping the winding when the layered bundle of conductive fibers reaches a predetermined thickness; The conductive fiber bundle is cut in the axial direction of the rotating drum and removed from the rotating drum, and the conductive fiber bundle is spread in a direction perpendicular or almost perpendicular to the conductive fibers to form a long sheet. In the method of forming a long mat by overlapping and splicing two sheets of the spread cotton sheet with their longitudinal end sides overlapped, the inclined part of the axial end side of the conductive fiber bundle when winding on the rotating drum is completed. width is 20~
Wind it up so that it is 150mm, and the thin part on the longitudinal end side of the rolled sheet is 5 to 30mm.
1. A method for producing conductive fiber mat, which comprises rolling out cotton so that it becomes like this, and overlapping and splicing a plurality of sheets of rolled cotton by overlapping the thin parts thereof. 5 The length of the bundle in the fiber direction is W, the basis weight of the non-slanted part is t, the width of the sloped part of the bundle is L, the length of the spread cotton sheet in the direction perpendicular to the cotton spread direction is W', the spread cotton is When the basis weight of the non-thin part of the sheet is t', L x t/t' x
The manufacturing method according to claim 4, wherein the spread cotton sheets are overlapped over a length calculated by W/W'.