JPS636250B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to an apparatus for producing a dry fine powder raw material in which short carbon fibers are uniformly split and mixed into single fibers.

(Prior Art) Carbon fibers having a diameter of about 5 μm to 20 μm made from raw materials such as pitch, and short fibers obtained by cutting these fibers into various lengths up to about 100 mm are known.

In addition, molded products or parts such as various mortars, concrete, glass, metals, resins, etc., made by uniformly dispersing and mixing the above-mentioned short carbon fibers, have significantly increased mechanical strength without impairing heat resistance or chemical stability. It is also known to increase.

However, when the short carbon fibers are in a uniform state before being shaped into powder or fluid raw materials for making this type of product, when some force is applied such as vibration, shaking, stirring, etc. Similar to when fine hair is swept together, adjacent short fibers tend to cross and overlap each other, forming soft, cotton-like aggregates. Although the adhesive bond between each short fiber in this aggregate is not very strong, it cannot be easily loosened with fingers. However, the above-mentioned properties of short carbon fibers are a major drawback when they are added to a powdered or fluid raw material before being shaped into a molded article and uniformly dispersed and mixed.

This is because if short carbon fibers are mixed into the raw material for a molded product in the form of an aggregate containing many small aggregates as described above, these aggregates will be removed during subsequent stirring, kneading, or other operations of the raw material. Depending on the dispersion method used, the individual fibers may not be separated, but on the contrary,
Even the short carbon fibers that have been separated once reaggregate into small spheres in the raw material for the molded product, and therefore it is not possible to obtain a state in which the short carbon fibers are uniformly dispersed as mutually separated single fibers in the raw material. It is.

Therefore, extremely complicated methods must be used to obtain materials such as mortar, slate plates, or cast concrete molded products that are uniformly mixed with the aforementioned short carbon fibers. That is, an aggregate of short carbon fibers is put into a suitable liquid material such as water to be kneaded with cement, or into a fluidized raw material containing cement, and is stirred little by little using a special mixer, etc., until it is uniformly fluidized. It is necessary to undergo an operation to form a dispersed solid-liquid mixture.

It goes without saying that the above method, which can be called a wet method, is inefficient and roundabout.

Recently, this type of molding material has come to be distributed as a single package containing a mixture of various solid material additives, and if necessary, it can be kneaded with water or the like to form mortar. This is a so-called premixed composite product.

However, due to the above-mentioned problems, it is not possible to make a one-package product of a solid powder/granular composite material containing short carbon fibers, and even if it were made, the short carbon fibers would aggregate over time, making it unusable. You won't get any more. This is extremely inconvenient and does not match the trends of the times.

As described above, although there are great expectations and demands for mortar containing short carbon fibers, slate boards, cement tiles, and concrete molded products due to their excellent properties, the actual implementation of these products is negligible. The current situation is that there is.

Therefore, it would be advantageous if it would be possible to obtain a composite cement in which each single fiber of short carbon fibers is relatively sufficiently separated from each other and dispersed together in a dry state from the beginning in a granular solid raw material containing the above-mentioned cement powder or the like.
Similarly, it would be of great benefit if short carbon fibers could be defibrated into single fibers and mixed into various molten glasses, molten resins, and uncured resin raw materials in a dry state as described above.

In order to do this, it is necessary to mechanically separate the aggregated aggregated short carbon fibers into single fibers by a so-called dry method without using a liquid medium, or to prevent the agglomeration tendency and to separate the separated single fibers. It is necessary to add it directly to the raw material. However, such dry defibration of short carbon fibers has been attempted by large companies, but none have succeeded.

(Objective) The object of the present invention is to provide an apparatus for obtaining a dry fine powder raw material in which short carbon fibers are uniformly dispersed and mixed in the form of single fibers.

(Structure) In order to achieve the above object, the present invention includes a pair of upper rotating bodies each having a large number of fine protrusions erected at small intervals on the surface thereof, and the tips of both fine protrusions are arranged facing each other with a slight gap between them. The thin protrusions of one rotary body with a slow circumferential speed hold down the small carbon short fiber lumps, and the thin protrusions of the rotary body with a faster circumferential speed perform relative movement to loosen the small pieces, and the carbon short fibers are placed above it. A fiber aggregate supply device is provided, and a pair of lower rotating bodies each having a large number of fine protrusions erected at small intervals on the surface thereof are disposed below, and each fine protrusion is arranged between the fine protrusions of the upper rotating body. The thin protrusions may intersect with each other slightly, do not intersect with each other, or have a slight gap, and at least one of the thin protrusions of the pair of lower rotating bodies is insufficiently separated by its own elasticity. The present invention is characterized in that the fibers are made into elastic fine wires that loosen small carbon fibers that are present in the fibers, and are provided with a means for passing between the lower rotary bodies and mixing the split carbon short fibers with a fine powder raw material. A detailed explanation will be given below based on examples. 1 is a thick-walled steel cylindrical upper rotating body with an outer diameter of 40 cm and a width of 80 cm; 2 is a similar upper rotating body with an outer diameter of 20 cm and a width of 80 cm; both upper rotating bodies 1 and 2 have tips on their surfaces. Sharp triangular, non-elastic thin protrusions 3 and 4 having a length of about 6 mm are fixed at a pitch of 3 mm, and the tips of the thin protrusions 3 and 4 face each other with an interval of about 1 mm. The upper rotating body 1 rotates every minute.
The upper rotating body 2 is arranged to rotate counterclockwise at a speed of 400 revolutions and clockwise at a speed of 20 revolutions per minute. A hopper 5 is disposed above the opposing portion of the pair of upper rotors 1 and 2, and collects short carbon fiber aggregates in which short carbon fibers with a diameter of about 15 μm and a length of about 3 mm are aggregated into small lumps of irregular size. 6 is included. A pair of lower rotating bodies 7 and 8 are disposed below the upper rotating bodies 1 and 2, and a large number of thin elastic wires 9 and 10 each having a length of 20 mm are erected at small intervals on the surface of the thin elastic wires 9 and 1.
0 intersect with the thin protrusions 3 and 4 of the upper rotating bodies 1 and 2, respectively, and the tips of the elastic thin wires 9 and 10 intersect with each other slightly. The lower rotating body 7 has an outer diameter of 13 cm and a width
The lower rotating body 8 has an outer diameter of 13 cm and a width of 80 cm and rotates clockwise at 30 revolutions per minute. 11 is a mixer into which fine powder raw materials such as cement mortar and admixtures are charged.

Next, the effect will be explained. 1 from Hopper 5
The short carbon fiber aggregates 6 supplied between the pair of upper rotating bodies 1 and 2 are held down by the fine protrusions 4 of the upper rotating body 2 whose circumferential speed is slow, while being held by the fine protrusions 4 of the upper rotating body 1 whose circumferential speed is high. It is loosened and most of it is separated into single fibers and falls downward. The short carbon fibers remaining attached between the fine protrusions 3 and 4 of the pair of upper rotary bodies 1 and 2 are the elastic fine wires 9 and 10 of the lower rotary bodies 7 and 8.
scraped off by. When the small pieces of short carbon fibers separated into unspecified amounts between the upper rotating bodies 1 and 2 pass between the elastic thin wires 9 and 10 of the lower rotating bodies 7 and 8,
While being held down by the thin elastic wire 10 with a slow circumferential speed, it is loosened by the thin elastic wire 9 with a high circumferential speed, and at this time the thin elastic wires 9 and 10 vibrate, and this vibration causes the carbon short fibers that have been insufficiently separated to be loosened. The small lumps are surprisingly completely divided into single fibers one by one. 1
The short carbon fibers passed through the pair of lower rotating bodies 7 and 8 and separated into single fibers fall into the mixer 11 as they are, and are uniformly mixed into fine powder raw materials such as cement mortar and admixtures. It will not re-agglomerate.

Note that at least one of the pair of lower rotating bodies may be an elastic thin wire, and the tips of the elastic thin wires or thin protrusions of the pair of lower rotating bodies may not intersect or may be slightly spaced apart. Alternatively, instead of the mixer, the fine powder raw material may be injected from the lower side of a pair of lower rotating bodies onto the separated and falling short carbon fibers to mix them.

(Effects) According to the present invention, a pair of upper rotating bodies each having a large number of fine protrusions erected at small intervals on the surface are arranged facing each other with the tips of both fine protrusions leaving a slight gap, so that one of the upper rotating bodies has a slow circumferential speed. The thin protrusions of the rotating body hold down the carbon short fiber lumps,
The fine protrusions of a rotary body with a high circumferential speed are used to cause relative movement to loosen the small lumps, and a short carbon fiber aggregate supply device is disposed above the small protrusions, and a large number of fine protrusions are provided on the surface of the rotating body below. A pair of lower rotating bodies are arranged upright at a small interval, and the thin protrusions of each of them intersect between the thin protrusions of the upper rotating body, and the thin protrusions intersect with each other slightly.
The thin protrusions on at least one of the pair of lower rotating bodies should be made of elastic fine wires that do not intersect or have a slight gap, and that use their own elasticity to loosen insufficiently divided short carbon fiber clumps. Since it is equipped with a means to mix the split carbon short fibers passed between the lower rotating bodies with the fine powder raw material, the carbon short fibers have a strong cohesive force and do not damage the short carbon fiber aggregates that have agglomerated into small lumps. A fine powder raw material in a dry state can be obtained by dividing the fibers one by one into single fibers and dispersing and mixing them as they are.

[Brief explanation of the drawing]

The figure is a front view of one embodiment of the present invention. 1, 2... Upper rotating body, 3, 4... Thin projection, 5
...Hopper, 6...Carbon short fiber aggregate,
7, 8... Lower rotating body, 9, 10... Elastic thin wire,
11...Mixer.

Claims (1)

[Claims] 1 A pair of upper rotating bodies each having a large number of fine protrusions erected at small intervals on the surface are arranged facing each other with the tips of both fine protrusions leaving a slight distance between them, and the fine protrusions of one of the rotating bodies have a slow circumferential speed. The short carbon fiber aggregates are held down by the small protrusions of a rotary body with a high circumferential speed, and the small protrusions of the rotary body move relative to each other so as to loosen the small aggregates. A pair of lower rotating bodies each having a large number of fine protrusions erected at small intervals on the surface are arranged, and each fine protrusion intersects between the fine protrusions of the upper rotating body, and the fine protrusions intersect with each other slightly. The thin protrusions of at least one of the pair of lower rotating bodies are used to loosen small carbon short fiber lumps that are insufficiently divided by their own elasticity. An apparatus for producing fine powder raw material in a dry state in which short carbon fibers are dispersed and mixed in the form of single fibers, and the short carbon fibers are made into elastic fine wires and are split by passing between lower rotary bodies and mixed with a fine powder raw material.