JP4277971B2 - How to unpack carbon fiber bundles - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for unwinding a carbon fiber bundle, and more particularly, from a wound bobbin wound with a carbon fiber bundle treated with a sizing agent, when the carbon fiber bundle is unwound, thread breakage and fluffing can be reduced. It relates to the method of unraveling.
[0002]
[Prior art]
Carbon fiber is widely used as a reinforcing material when forming or manufacturing a composite material such as fiber reinforced resin (CFRP). In general, when a carbon fiber bundle is wound around a bobbin in a manufacturing process, it is subjected to a surface treatment in advance with a sizing agent in order to improve the interfacial adhesion with the matrix resin of the fiber reinforced resin or to improve the convergence. It is wound up.
[0003]
The sizing agent is mainly composed of an uncured thermosetting resin having a relatively low molecular weight such as an epoxy resin. However, since the sizing agent has adhesiveness at room temperature, a carbon fiber bundle is wound around a winding bobbin. In this state, an adhesion phenomenon occurs between the winding layers, and a high peeling resistance is generated when the carbon fiber bundle is unwound. On the other hand, the carbon fiber bundle has a characteristic that it is brittle and easily broken because the elongation at break is almost zero in the state of the bare yarn before being combined.
[0004]
For this reason, when the carbon fiber bundle is subjected to a large peeling resistance when unwound from the bobbin, there is a problem that yarn breakage and fluff are likely to occur due to strong bending and tensile loads. When yarn breakage occurs during production, the production process is forced to be interrupted, so the operating rate is lowered, and the quality is lowered by continuing the yarn breakage. In addition, fluffing was a cause of quality degradation.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to provide a carbon fiber bundle unwinding method that can reduce yarn breakage and fluffing when unwinding from a wound bobbin.
[0006]
[Means for Solving the Problems]
The method for unwinding the carbon fiber bundle of the present invention comprises unwinding the carbon fiber bundle from a wound bobbin wound with a carbon fiber bundle treated with a sizing agent mainly composed of an uncured thermosetting resin. When supplying to the next step, the winding bobbin is unwound while being heated, or unwound while maintaining a heat-retaining state by preheating.
[0007]
Thus, when unwinding the carbon fiber bundle from the bobbin bobbin, the bobbin bobbin is heated, or preheated and maintained in a heat retaining state, so that the uncured thermosetting resin sizing agent is softened. To do. Accordingly, the peeling resistance between the carbon fiber bundles when the carbon fiber bundle is unwound is reduced, the occurrence of yarn breakage and fluffing is reduced, and the operability is improved and the quality can be improved.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the type of the sizing agent used for the surface treatment of the carbon fiber bundle is not particularly limited as long as an uncured thermosetting resin is a main component. For example, an epoxy resin, an unsaturated polyester resin, a vinyl ester resin, etc. can be illustrated.
[0009]
In the present invention, the heating of the bobbin that is performed when the carbon fiber bundle is unwound may be performed by heating the bobbins one by one or by heating in units of a plurality of units. You may do it. This heat treatment of the bobbin bobbin softens the sizing agent that has been surface-treated on the carbon fiber bundle, and reduces the peeling resistance between the winding layers. Can be reduced. In such a heat treatment, the bobbin bobbin may be heated in advance before being subjected to the unwinding step, and unwinding while maintaining the heat retaining state obtained by the preheating.
[0010]
It is preferable that the heating temperature in the heat treatment or the warming temperature after preheating is in the range of 40 to 90 ° C. When temperature is lower than 40 degreeC, the softening of a sizing agent will become inadequate and the thread breakage prevention effect will reduce. Further, when the temperature is higher than 90 ° C., the yarn breakage preventing effect is sufficient, but since the effect is saturated, there is a demerit that extra heating energy is consumed. Furthermore, since the curing reaction of the sizing agent is induced, the compatibility with the matrix resin is hindered, and there is a disadvantage that the interfacial adhesion is lowered.
[0011]
As long as the present invention is a process of unwinding a carbon fiber bundle, the application process in particular is not limited. For example, weaving preparation process such as warping process, weaving process, prepreg manufacturing process, filament winding process, dipping (impregnation) process, pultrusion (drawing) process, roping method extrusion (extrusion) process, chopped fiber cutting process, etc. It can be illustrated.
[0012]
FIG. 1 illustrates the case where the present invention is applied to a warping process of a carbon fiber bundle.
[0013]
In FIG. 1, reference numeral 1 denotes a winding bobbin on which a carbon fiber bundle Y surface-treated with a sizing agent is wound, and a large number of winding bobbins 1 are suspended on a creel stand 2 in multiple rows and stages. As the sizing agent, one having an uncured thermosetting resin such as an epoxy resin as a main component is used. Reference numeral 3 denotes a warping drum. When the warping drum 3 is rotationally driven, the carbon fiber bundles Y are unwound from a large number of winding bobbins 1, and the carbon fiber bundles Y are spaced at regular intervals. And are wound up on the warping drum 3.
[0014]
A large number of wound bobbins 1 suspended in multiple rows and stages on a creel stand 2 are accommodated in a closed space 4 surrounded by a transparent resin sheet 4a. The closed space 4 is provided with an exhaust port 5 and a supply port 6 at an upper part and a lower part, and a duct 7 connecting a blower 8 and a heater 9 is connected therebetween. In the operating state, the blower 8 and the heater 9 suck the air in the closed space 4 from the discharge port 5 to the duct 7, and the heater 9 heats and supplies the air to the closed space 4 again from the supply port 6. It is like that. By repeating the circulation of the heated air in this way, the multiple bobbins 1 in the closed space 4 are heated.
[0015]
As described above, when the carbon fiber bundle Y is unwound from a large number of the wound bobbins 1 and wound onto the warping drum 2, the surface of the carbon fiber bundle Y impregnated is obtained because the wound bobbin 1 is heated. The sizing agent is softened, and the softening of the carbon fiber bundle Y on the winding bobbin 1 reduces the mutual adhesive force, and can be easily peeled even with a small unwinding tension. Therefore, the carbon fiber bundle Y is unwound without being applied with an excessive bending load. Therefore, it is possible to improve the operability and the quality without causing yarn breakage or fluffing.
[0016]
FIG. 2 illustrates a case where the present invention is applied to a weft bobbin for wefts in a carbon fiber weaving process.
[0017]
Only one winding bobbin 1 for weft is stored in the closed space 4, and a carbon fiber bundle Y having a certain length is unwound from the winding bobbin 1 every time weft insertion. Heated air is supplied to the closed space 4 from the supply port 6 and is exhausted from the exhaust port 6 so that the inner bobbin 1 is constantly heated.
[0018]
In the case of the embodiment of FIG. 2 as well, the carbon fiber bundle Y is softened by heating the surface sizing agent, so that the peel resistance when unwound from the bobbin 1 is reduced, and excessive bending or tension is applied. It is unwound with a small unwinding tension without receiving a load. Accordingly, the operability is improved and the quality is improved without causing yarn breakage or fluff.
[0019]
【Example】
Using a plurality of wound bobbins wound with carbon fiber bundles (elastic modulus 230 GPa, tensile strength 3,530 MPa) surface-treated with a sizing agent mainly composed of an epoxy resin, while unwinding at a unwinding speed of 120 m / min When performing the warping to be wound up on the warping drum, the apparatus shown in FIG. 1 is used to supply heated air at 70 ° C. to the closed space to heat the bobbin bobbin (Example). The number of occurrences of yarn breakage during the process was examined in the case of normal temperature of 20 ° C. (comparative example).
[0020]
As a result, in the examples of the present invention, no yarn breakage occurred, but in the method of the comparative example, yarn breakage of 40 times / 10 ⁵ m occurred.
[0021]
【The invention's effect】
As described above, according to the present invention, when the carbon fiber bundle is unwound, the winding bobbin is heated or preheated so as to be kept warm. It is possible to reduce the peeling resistance between them and easily unwind them without applying an excessive bending load to the carbon fiber bundle. Therefore, yarn breakage during unwinding does not occur and occurrence of fluffing can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of a warping process for carrying out the present invention.
FIG. 2 is a schematic diagram showing a portion of a weft bobbin for wefts in a weaving process for carrying out the present invention.
[Explanation of symbols]
1 Winding Bobbin 2 Creel Stand 3 Warping Drum 4 Closed Space 5 Exhaust Port 6 Supply Port 7 Duct 8 Blower 9 Heater F Carbon Fiber Bundle

Claims (3)

When winding a carbon fiber bundle treated with a sizing agent mainly composed of an uncured thermosetting resin, the carbon fiber bundle is unwound and supplied to a higher-order process. A method for unwinding a carbon fiber bundle that unwinds while heating or unwinds while maintaining a heat-retaining state by preheating. The method for unwinding a carbon fiber bundle according to claim 1, wherein the winding bobbin is housed in a closed space, and the winding bobbin strip is heated by supplying a heating gas to the closed space. The method for unwinding a carbon fiber bundle according to claim 1 or 2, wherein a heating temperature of the bobbin bobbin or a heat retaining temperature after preheating is set to 40 to 90 ° C.

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