Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1998-10-13
2002-11-26
Maki, Steven D. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C057S022000, C057S023000, C057S202000, C057S350000, C156S158000, C156S502000, C264S029200, C423S447400
Reexamination Certificate
active
06485592
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a precursor fiber bundle for manufacture of carbon fibers, a production apparatus thereof, and a method for manufacturing a carbon fiber bundle. Particularly, the present invention relates to a series of precursor fiber bundles for manufacture of carbon fibers, composed of at least two fiber bundles each of which comprises 30,000 or more filaments and which fiber bundles are joined each other at the terminal end of one and the starting end of the other one directly or through an intervening fiber bundle, a production apparatus thereof, and a method for manufacturing a carbon fiber bundle using the series of precursor fiber bundles for manufacture of carbon fibers. The series of precursor fiber bundles for manufacture of carbon fibers is stabilized to make a stabilized fiber bundle which is further carbonized to make a carbon fiber bundle.
BACKGROUND ART
Carbon fibers have been used as reinforcing materials of aircraft and sporting goods. Recently, carbon fibers begin to be used also as architectural and civil engineering materials and reinforcing materials for members of energy related apparatuses, and such demands are growing rapidly. To meet these demands and furthermore to further increase the demands, carbon fibers having at least conventional properties and less expensive than the conventional carbon fibers are being demanded.
To supply less expensive carbon fibers to the market, the production cost of carbon fibers must be lowered. One method for reducing the cost is to heat-treat (stabilizing and carbonizing) a precursor fiber bundle for manufacture of carbon fibers which fiber bundle has far more filaments than before, for improving the productivity of carbon fibers.
However, if the number of filaments in a precursor fiber bundle increases, i.e., if the filament density becomes higher, heat accumulation in the precursor fiber bundle during stabiizing treatment performing in an oxidizing atmosphere (air) tends to be large. As a result, the filaments are likely to generate heat, and the oxidation reaction of filaments in the stabilizing treatment tends to run away.
So, where the filament density is higher, the stabilizing temperature in the stabilizing treatment must be set at a level lower than that in the stabilizing treatment of a precursor bundle having lower filament density, to take a longer time for the stabilizing treatment, in order to prevent the filament breaking due to the runaway reaction.
However, if the stabilizing treatment temperature is lowered greatly, the stabilizing treatment time becomes too long, and it can happen that the productivity of stabilizing treatment is not improved even though the filament density is higher.
On the other hand, the stabilizing treatment process comprises the steps of continuously supplying a series of precursor fiber bundles from the inlet of a stabilizing treatment furnace into the furnace, stabilizing it in the furnace, to produce a stabilized fiber bundle, and continuously taking out the stabilized fiber bundle from the outlet of the furnace. The precursor fiber bundle continuously supplied into the stabilizing treatment process must be a series of precursor fiber bundles formed by joining a plurality of precursor fiber bundles at the terminal end of one and the starting end of another, each of which bundles is wound around bobbins or spools or contained in cans with a certain limited length.
However, where precursor fiber bundles having a high filament density are simply joined each other, the filament density at the joined portion becomes very higher than the filament density at the other portions (main bundle portions). Simply, the filament density becomes double. Therefore, in the stabilizing treatment, the oxidation reaction of filaments at the joined portion tends to run away compared to the main bundle portion.
A method for splicing or joining precursor bundles is described in Japanese Patent Publication (Kokoku) No. 53-23411. In this method, precursor fiber bundles are spliced each other at the mating ends into a series of precursor fiber bundles, and the series of precursor fiber bundles are treated to be stabilized. Then, the joining portion of the series of stabilized fiber bundles is cut off and removed, and each of the bundles are re-spliced into a series of stabilized fiber bundles and treated to be carbonized.
Japanese Patent Laid-Open (Kokai) No. 54-50624 describes a method of applying a flame resistant compound such as silicone grease to the joining portions.
Furthermore, Japanese Patent Laid-Open (Kokai) No. 56-37315 describes a method comprising heat-treating the ends (the starting end and the terminal end) of precursor fiber bundles and then the precursor fiber bundles are spliced each other by a specific splicing method.
Moreover, Japanese Patent Laid-Open (Kokai) No. 58-208420 describes a method for interlacing the terminal end of one precursor fiber bundle and the starting end of another precursor fiber bundle by a high speed fluid.
However, in any of these methods, since the filament density at the joining portion becomes very higher than that of the main bundle portion, burning, breaking, etc. of filaments are likely to be caused by the heat accumulation during stabilization treatment.
Japanese Patent Publication (Kokoku) No. 60-2407 describes intervening stabilized fibers or carbon fibers at the splicing portion for inhibiting the heat accumulation. However, since the square knot is used for the joining portion, the knot is tightened and the filament density becomes higher. So, the heat accumulation inhibiting effect is small.
As a method for improving these disadvantages, Japanese Patent Publication (Kokoku) No. 1-12850 describes interlacing precursor fiber bundles with each other or interlacing a precursor fiber bundle with a stabilized fiber bundle.
FIG. 1
is a perspective view showing an example of the method. In this method, the mating ends
2
a
and
2
b
of the fiber bundles to be joined are simply overlaid in the form of the bundles as they are, inserted into an interlacing treatment chamber
4
of a fluid interlacing nozzle
1
, relaxed by about 5 to 60%, and treated by a high speed fluid jetted from two nozzle holes
3
for interlacing the filaments at both ends
2
a
and
2
b
with each other. The method for joining with an intervening of a stabilized fiber bundle has an effect that the heat accumulation at the joining portion makes small compared to the direct joining of precursor fiber bundles since the stabilized fibers little generate heat in the stabilizing process.
As for the fluid interlacing nozzle used in this conventional method, as shown in
FIG. 1
, the high speed jets injected from the two nozzle holes
3
installed in the small entangling treatment chamber
4
collide with each other in the interlacing treatment chamber
4
, to produce turbulent flow which opens the fiber bundles for interlacing the filaments with each other. This method is effective for fiber bundles small in the number of filaments constituting them.
However, if the number of filaments constituting each of the fiber bundles to be joined is very large, the jets injected from the nozzle holes do not hit all the filaments of the fiber bundles, and the fiber bundles are not interlaced at filament level and it remarkably happens interlacing between sub-bundles of filaments each other. Such interlaced sub-bundles of filaments occur unevenly at the joining portion and portions with high filament densities are locally formed, and heat is likely to be accumulated there.
An interlacing based on several interlaced sub-bundles of filaments is weak in joining strength since interlacing strength between filaments is weak. The examples described in Japanese Patent Publication (Kokoku) No. 1-12850 disclose only fiber bundle comprising up to 12,000 filaments. If precursor fiber bundles each of which comprises 30,000 or more filaments handling in the present invention are joined at their mating ends directly or through an intervening stabilized fiber bundle according
Endo Makoto
Sano Takao
Sekido Toshihide
Yoshimura Kousuke
Maki Steven D.
Schnader Harrison Segal & Lewis LLP
Toray Industries Inc.
LandOfFree
Precursor fiber bundle for manufacture of carbon fiber,... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Precursor fiber bundle for manufacture of carbon fiber,..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Precursor fiber bundle for manufacture of carbon fiber,... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2941165