JPH0713335B2 - Carbon fiber disentanglement method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a tow of carbonaceous fibers, and more particularly to a method for defibrating a tow of carbon fibers.

(Prior Art) Carbon fiber is used as a composite material with various matrices, for example, a material (prepreg) impregnated with a matrix resin such as epoxy resin, polyamide resin, or phenol resin is molded by various molding methods, As a fiber reinforced plastic, it is used as a fishing rod, a golf shaft, a cash register for skis, sports, and industrial materials such as leaf springs, springs and gears.

The carbon fibers used in this manner are synthetic fiber tows such as polyacrylonitrile-based fibers, flame-resistant by heating in an oxidizing atmosphere such as air, or melt-spun coal-based or petroleum-based pitches. The obtained pitch fiber tow,
What is made infusible by heating in an oxidizing atmosphere such as air,
Further, it is manufactured by heating in a high temperature inert gas atmosphere to carry out carbonization or graphitization.

However, the flame-resistant or infusibilized fiber tow (hereinafter simply referred to as infusible fiber tow), and the carbonized or graphitized fiber tow (hereinafter simply referred to as carbon fiber tow) are The fiber tow lacks suppleness due to the heat treatment of the fiber itself in each process and the oil agent used in
Or fiber single yarns are fused and exhibit uneven quality,
Since the single yarn dispersion in the matrix resin becomes non-uniform and the homogeneity of the composite material is impaired, it is liable to be fused at the stage where any treatment of flame resistance, infusibilization, carbonization or graphitization is performed. Must be defibrated without Conventionally,
As the defibration method of the infusible fiber tow or the carbon fiber tow,
A method of subjecting the fiber tow to turbulence, a method of bending the fiber tow through a guide such as a bar, a wire, and a rotating pin while bending it in a zigzag manner, and a method of contacting the curved surface of a roll having a convex curved surface (JP-A-55-57015). (Japanese Patent Laid-Open No. 57-89638) and a method of defibrating in fluid (Japanese Patent Laid-Open No. 57-89638).

(Problems to be Solved by the Invention) However, all the conventional methods lack flexibility,
Alternatively, it is not yet sufficient to defibrate the infusible fiber tow or the carbon fiber tow in a state where the fibers are fused together.

(Means for Solving Problems) Therefore, the present inventors have found that the fiber tow lacks flexibility, or the infusible fiber tow in a state in which the fibers are fused together, or
As a result of extensive studies on a method of defibrating a carbon fiber tow into a supple and non-fused state without causing fluffing by a simple operation, as a result, one-sided taper roller in which the fiber tows are alternately arranged ( Hereinafter, it was found that this object can be easily achieved by contacting the inclined surface of the taper roller, which is in contact with the fiber from one side, and the present invention has been completed based on this finding.

That is, the gist of the present invention is characterized in that the tow of the carbonaceous fiber is brought into contact with the inclined surfaces of at least two taper rollers arranged so that the inclination directions of the inclined surfaces are substantially alternating. And defibration method of carbon fiber.

Hereinafter, the present invention will be described in detail, with a tow of carbonaceous fiber used in the present invention, a polyacrylonitrile-based fiber,
A fiber tow such as a cellulosic fiber or a polyvinyl alcohol fiber is flame-resistant, carbonized or graphitized, or a Pitch-based fiber tow is infusibilized, carbonized or graphitized.

In particular, in the case of Pitch-based fiber tow, as the heat treatment progresses from infusibilization to carbonization and graphitization, the degree of flexibility of the tow or the fusion of the fibers is likely to be stronger. It is also possible to once disintegrate at the stage of the fused fiber tow and further disintegrate at the stage of the carbon fiber tow.

The number of single yarns forming the tow is not particularly limited, but usually 30
0 to 300,000 lines, preferably 500 to 60,000 lines are used.

Further, the taper roller used in the present invention is a roller having an inclined side surface, specifically, a roller having a conical shape as shown in FIG. 3 or a roller similar thereto, and the contact surface with the carbonaceous fiber tow is the roller central axis. Angle α with 4 is 3 to 50
The inclined surface 6 has a slope of 6 degrees, preferably 5 to 30 degrees. If the angle α is less than 3 degrees, defibration cannot be sufficiently performed, and if it exceeds 50 degrees, the fiber tow is biased toward the small diameter side or the tow is transiently bent between the rollers, so a smooth defibration operation is performed. Becomes difficult. Also, the size is appropriately selected depending on the single tow of carbonaceous fiber, the number of tows to be defibrated or the degree of defibration, etc., but usually the diameter d0.5 to 5c of the large diameter portion.
It is preferable that the curved portion 7 is provided at the small diameter portion and the brims 8 are provided at both end portions as shown in FIG. 4 in view of the defibrating operation.

In the present invention, it is important to dispose the taper roller as described above so that the inclination directions of the inclined surfaces thereof are substantially alternated. However, when the taper rollers are disposed so that the inclination directions thereof are substantially alternated. Means that the small-diameter portion and the large-diameter portion of the taper roller are arranged opposite to the taper roller adjacent to each other. The case where the alternating regularity is partially disturbed, such as the parts being in the same direction or having a neutral roller in the middle, is also included.

The size, number and arrangement of the taper rollers are appropriately selected mainly depending on the degree of lack of flexibility of the carbonaceous fiber tow and the degree of fusion of the fibers. The number of the same size used is usually 2 to 100, preferably 4 to 60, more preferably 6 to 40, but it is also possible to appropriately combine 2 to 5 types of tapered rollers having different sizes. it can.

The rollers may be arranged in a linear type, an S type, a W type, an arc type, or a combination thereof. The straight case is the first
The drawings and FIG. 2 will be described.

FIG. 1 is a plan view of an example of a linear type, and FIG. 2 is a front view of the same. The taper roller is rotatably inserted in a central shaft 4 linearly provided on a roller support frame 5 such that inclined surfaces 6 are alternately arranged. Also, as shown in FIG. 2, the distance L between the two roller central shafts 4 is usually 0.5 to 5 cm, although it depends on the angle α of the roller surface and the size of the roller. The carbonaceous fiber tow 3 is stretched between the guide rollers 2 on the opposite side by alternately passing from above and below the inclined surface 6 of the adjacent taper roller 1 from the guide roller 2.

Then, by rotating the take-up bobbin (not shown) to pull the carbonaceous fiber tow 3 in the direction of the arrow, the carbonaceous fiber tow 3 comes into contact with the inclined surface 6 having alternated inclination directions, and The force of lateral displacement of the carbonaceous fiber tow with respect to the direction of travel will be applied alternately. In other words, the ironing operation is performed so as to peel off the fusion of the fibers.

In the case of S type, as shown in FIG. 5, the taper roller 1 is S
It is arranged in a V shape.

The tow 3 made of carbonaceous fiber is stretched so as to come into contact with the outside of the taper roller arranged in the S shape, and is pulled in the direction of the arrow ((a) in FIG. 5). As a method of stretching the tow of the carbonaceous fiber, other methods of alternately stretching the inside and the outside of the taper roller ((b) in FIG. 5) or two outsides of the taper roller and the inside Various methods such as a method of stretching one piece in order ((c) of FIG. 5) can be adopted.

In the case of the W type, the taper rollers 1 are arranged in two rows as shown in FIG. The carbonaceous fiber tow 3 is stretched in a W shape between the two rows of taper rollers 1 and pulled in the direction of the arrow.

In the case of the arc type, as shown in FIG.
Are arranged in an arc shape, or, as shown in FIG. 8, the taper roller 1 is arranged in an arc shape on the rotary plate 9. The carbonaceous fiber tow 3 is stretched so as to come into contact with the outer side of the taper roller arranged in an arc shape and pulled in the direction of the arrow ((a) in FIG. 7). In the case of the circular arc type as well, similar to the S-shaped type, various stretching methods (for example, (b) in FIG. 7,
(C)) may be performed.

Although the defibration operation can be performed in the gas phase, a substance that is easily soluble in water or water, for example, an anionic surfactant, a cationic surfactant, a nonionic surfactant, an amphoteric surfactant or a surfactant mixture thereof is used. If the carbonaceous fiber tow is moistened with water or an aqueous solution of the water-soluble substance, fluffing is reduced and the defibration operation can be performed smoothly. preferable. The concentration of the water-soluble substance varies depending on the substance, but in the case of a surfactant, it is better to set it to 0.01 to 5 wt%, and if the substance remains an obstacle in the fiber after defibration, After defibration, the substance may be removed by washing with water.

Furthermore, as substances easily soluble in water, acids such as sulfuric acid and nitric acid,
Alkali such as caustic soda and caustic potash, or salts such as sodium chloride and sodium carbonate can also be used.
Then, the tow of carbonaceous fibers disintegrated by using the water solubility of these substances can be subjected to the surface treatment such as wet oxidation and electrolytic oxidation using the aqueous solution of these substances.

(Effect of the Invention) As described in detail above, according to the present invention, the tow of the carbonaceous fiber is brought into contact with the inclined surfaces of at least two taper rollers arranged so that the inclined directions of the inclined surfaces are alternated. Since the fiber lacking flexibility or partially fused can be defibrated into a flexible state by a simple operation of performing the defibration, it is an extremely excellent method for defibrating carbonaceous fibers.

(Examples) Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

Example 1 Large diameter (d) 1.6 cm, length (l) 2 cm, inclination angle (α) 13
Tapered roller with a distance between the roller center axes (L) of 2 cm
Approximately 0.1% by weight of a device in which two guide rollers are arranged in a mold as shown in Fig. 7A, and 10 guide rollers are provided at both ends and in the middle.
It was placed in a water tank containing an aqueous solution of the anionic surfactant.

A carbon fiber tow with a single yarn diameter of 10μ and 3000 single yarns obtained by melt spinning a coal-based pitch into this device, making it infusible and carbonizing, was stretched as shown in Fig. 7, and further from this device. The defibrated tow that came out was wound with water at a speed of about 2 m / min, and then dried.

The defibrated tow thus obtained is supple and free from fusion of fibers, impregnated in an epoxy resin of Matricex, and after curing, the cross section with respect to the longitudinal direction of the tow is observed under a scanning electron microscope. As shown in (1), the single yarn 10 was uniformly dispersed in the epoxy resin 11 and showed excellent homogeneity.

Contrary to this, the tow of the carbon fiber before the actual defibration is lacking in flexibility, there are many fusions of the fibers, and observing the cross section in the same manner, the single yarn 10 aggregates as shown in FIG. 10. , And was unevenly dispersed in the epoxy resin 11, resulting in poor homogeneity.

Example 2 A defibrated tow was obtained in the same manner as in Example 1 except that the carbonaceous fiber tow was an infusible fiber tow, and further carbonized to obtain a carbon fiber tow. The tow was supple and free from fusion of fibers. When the cross section was observed in the same manner as in Example 1, the single yarns were uniformly dispersed and homogeneous.

[Brief description of drawings]

1 is a plan view of an example of an apparatus used in the present invention, FIG. 2 is a front view of the same, FIGS. 3 and 4 are front views of an example of a taper roller used in the present invention, and FIGS. FIGS. 9 to 10 are explanatory views showing another example of the arrangement of the rollers, and FIGS. 9 to 10 are schematic views showing the dispersed state of the fibers in the epoxy resin. 1: Tapered roller, 2: Guide roller 3: Carbon fiber tow 6: Tapered roller inclined surface

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-48-41016 (JP, A) JP-A-57-89636 (JP, A) JP-B-40-10489 (JP, B1)

Claims (7)

[Claims] 1. A tow of carbonaceous fibers is brought into contact with the inclined surfaces of at least two one-side taper rollers arranged so that the inclined directions of the inclined surfaces are substantially alternating. A method of defibrating carbonaceous fibers. 2. The method according to claim 1, wherein the carbonaceous fiber tow is moistened with water and brought into contact with the inclined surface of the one-side taper roller. 3. The method according to claim 1, wherein the tow of carbonaceous fiber is brought into contact with the inclined surface of the one-side taper roller in water. 4. The angle of the inclined surface of the one-side taper roller is 3 to 50 degrees with respect to the central axis of the roller, according to any one of claims 1 to 3. The method described. 5. The carbonaceous fiber is a pitch-based fiber, a polyacrylonitrile-based fiber, a cellulosic fiber or a polyvinyl alcohol-based fiber infusibilized or flame-proofed. The method according to any one of item 3. 6. The carbonaceous fiber is a pitch-based fiber, a polyacrylonitrile-based fiber, a cellulosic fiber or a polyvinyl alcohol-based fiber, which is carbonized and / or graphitized after being rendered infusible or flame resistant. The method according to any one of claims 1 to 3, wherein: 7. The method according to claim 2, wherein the water contains a surfactant or an alcohol.