JP2006151690A - Carbon fiber package - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide carbon fiber superior in dispersiveness and high speed loosening-extending performance, a package optimal for such carbon fiber, and a fiber reinforced composite material having a superior quality and a grade. <P>SOLUTION: In this carbon fiber package with yarn wound on an internal loosening-extending bobbin, the loop spreading ratio x% satisfies an expression 1 : 100<x<150. The loop spreading ratio x% and a crest angle w° of the package innermost layer also satisfy an expression 2 : 300<xw<3000. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a carbon fiber package. More specifically, the present invention relates to a carbon fiber package for high-speed unwinding of carbon fibers having a high yarn spread rate.

  In recent years, as the amount of carbon fiber used has increased, its field of use has expanded and it has been processed in various ways. Among these processing methods, it is a high-speed processing such as woven fabric, filament winding, SMC (sheet molding compound), and direct spraying. There is a process that becomes. For such applications, unwinding by vertical cutting from a package wound around a bobbin is generally used. However, carbon fiber is extremely low in elongation compared to organic fiber or glass fiber, so it is easy to fluff. In such a high-speed supply method using vertical cutting, troubles often occurred during unraveling. In particular, in the type of carbon fiber that is easy to handle yarns and has low converging properties, part of the fluff and scattered yarns adheres to the surface of the package, and the yarn that is pulled out becomes entangled to form a ring on the surface of the package. There were cases where it was impossible to hesitate.

  Conventionally, there have been few reports on packages for improving the unwinding properties of carbon fibers, and further, there are descriptions on the internal preparation and the package for internal preparation and dissolution in Patent Document 1, Patent Document 2, and Patent Document 3. To the extent that All of these are related to bobbins wound with carbon fiber, and bobbins and packages that can be continuously processed in high order, and all of them have sufficient knowledge about yarn characteristics and packages. It wasn't.

Easy-to-spread yarns are usefully used for reasons such as improved resin impregnation and improved molded product characteristics and quality by uniformly dispersing in all high-order processing such as prepreg, SMC and direct spray. On the other hand, there has been a problem that trouble is likely to occur in the drawability of the yarn, that is, the unwinding property at high speed. For example, some yarn bundles may become tangled because they are easy to judge, or may be caught by rubbing against the package surface or the end surface with minute fluff of the yarn bundle, and may not be pulled out well. There is also a phenomenon that the working environment is deteriorated by fluff flying around when unwinding. As a result, there is a problem that productivity has to be reduced, for example, the processing speed is reduced, fluff is mixed into the product, and the quality and quality of the product is lowered, and the yield of the product is lowered. There was a case.
In view of these current conditions, the present inventors have intensively studied a carbon fiber package that is excellent in high-speed unwinding property and excellent in dispersibility. As a result of the investigation, it was found that a product used for high-speed unwinding of carbon fibers with low convergence can be fundamentally solved by winding up with a bobbin for internal unwinding. .
Japanese Patent No. 2884142 Japanese Patent Laid-Open No. 10-212070 Japanese Examined Patent Publication No. 3-72547

  In view of the above problems, an object of the present invention is to provide a carbon fiber excellent in dispersibility and high-speed unwinding property and to provide an optimal package for obtaining such a carbon fiber. Another object of the present invention is to provide a fiber reinforced composite material having good quality and quality.

The present invention employs the following means in order to solve the above problems. That is,
1. A carbon fiber package in which a yarn satisfying the following formula (1) with a yarn breaking rate x [%] is wound around a bobbin for taking up and unwinding.

100 <x <150 (1)
2. 2. The carbon fiber package according to 1, wherein the yarn spread ratio x [%] and the innermost twill angle w [°] of the package are wound so as to satisfy the following formula (2).

300 <x · w <3000 (2)
3. The carbon fiber package according to 1 or 2, which is wound so that the winding diameter a and the winding width b satisfy the following formula (3).

  0.5 ≦ a / b ≦ 3 (3)

  In the present invention, a product excellent in quality and quality of a high-order processed product is obtained by winding a carbon fiber having a yarn breaking rate x [%] 100 <x <150 around a bobbin for internal use that is not normally used. Can be provided. In addition, resin-impregnated sheets such as prepreg, SMC, and direct spray manufactured using the carbon fiber unraveled from the package of the present invention and the fabric obtained therefrom are excellent in quality such as fluff and resin impregnation state. is there. Furthermore, the fiber reinforced composite material obtained from such carbon fiber and fabric has few resin voids and is excellent in quality.

  The carbon fiber package of the present invention is characterized in that a carbon fiber having a yarn spreading rate measured by a method described later of greater than 100% and less than 150% is wound around a bobbin such as a paper tube for internal use. In the present invention, the yarn spreading rate is an item for evaluating the ease of spreading a yarn bundle (the measurement method will be described later), and indicates that the yarn breaking rate is easier to fly. A fiber bundle with a yarn spreading ratio of 100% or less has good convergence and is difficult to scatter. Therefore, the unwinding property itself is good, but since the convergence is too good, the resin is not uniformly dispersed, so the resin is not bundled. Difficult to enter, may cause problems such as quality and quality of the molded product. In addition, since the yarn with a yarn spread rate of 150% or more is unstable in shape, the package is liable to collapse, obstructing large packaging, the package collapses and cannot be used during transportation, and handling properties are extremely reduced. . Accordingly, the yarn separation rate x [%] is in a good range of 100 <x <150. More preferably, 105 <x <145, and a further preferable range is 110 <x <140. Carbon fibers having a yarn spreading ratio x [%] in the range of 100 <x <150 are preferably obtained as follows.

  The raw fiber may be any of polyacrylonitrile fiber, pitch fiber, rayon fiber, etc., but for the reason that a carbon fiber bundle excellent in scratch resistance can be obtained, polyacrylonitrile fiber is used. It is preferable to use a raw material fiber. The number of single fibers is suitably in the range of 3,000 to 50,000, preferably 10,000 to 50,000 in terms of productivity and resin impregnation. The spinning method usually includes wet and dry wet methods. The polyacrylonitrile filament obtained by the dry and wet spinning method is fired, and the ratio Sr / Sp of the actual surface area Sr to the projected area Sp is 1 ≦ Sr / Sp <1. Carbon fiber in the range of 05, preferably 1 ≦ Sr / Sp ≦ 1.03, is preferably used because it is highly resistant to friction with the guide. Adjustment of the yarn spreading rate can be achieved by changing the amount and composition of the sizing agent, or adjusting the production conditions, firing conditions and winding conditions of the raw fiber. The sizing agent is not particularly limited, and examples thereof include an aqueous solution or a dispersion of an aliphatic or aromatic epoxy resin. An emulsifier is usually used for the dispersion. The sizing agent preferably has a softening point (hereinafter referred to as SZ softening point) of a 100 ° C. dried product of 50 ° C. or less, more preferably 20 ° C. or less. Moreover, as a composition component of a liquid dry substance, what is an aliphatic epoxy resin or its emulsion is preferable. As a method for applying the sizing agent, a known method such as a transfer method, a dipping method, or a spray method can be employed. Although the drying method is not specifically limited, For example, the method of drying for 1-2 minutes in 200 degreeC air is mentioned. Carbon fibers having a sizing agent deposition amount (hereinafter referred to as SZ deposition amount) of 0.1 to 3% by weight, preferably 0.3 to 3% by weight, are preferably used, and more preferably 0.3 to 3% by weight. 2% by weight, and more preferably 0.5 to 1.6% is suitable for adjusting the yarn spreading rate. Moreover, since the packaging workability of the package surface damage preventing film may be inferior, it is preferable that the yarn end at the beginning of winding on the bobbin is exposed from the package within 20 mm.

  In general, when longitudinally unraveling from the outer layer, the state varies depending on the drawing speed, the drawing angle, the length to the guide, the hardness of the thread, etc., but usually ballooning as shown in FIG. 2 occurs. . However, since the yarn in the range of the yarn spreading ratio of the present invention is soft, the ballooning tends to be relatively small, and the surface of the package and the drawn yarn are likely to contact each other. When contacted, fluff is easily generated, and when it is caught, the yarn may be tangled on the surface of the package and cannot be unwound. In addition, when wound at a high density, it may become impossible to unwind by mixing fibers above and below the wound layer. In such a case, it is possible to solve the problem by taking up the inside which does not cause the ballooning, that is, by taking the form of a package wound around the inside bobbin. In the present invention, an internal bobbin is also required for an external bobbin, such as winding a carbon fiber bundle, having no damage to the carbon fiber due to shape loss during packing or transportation, etc. In addition to the above characteristics, it is required that the thread bundle can be easily removed at the time of use. For example, a tape-shaped fixing band is attached, or a thread having a spiral perforation as shown in FIG. What is known conventionally may be used. By making the winding ratio, tension, guide shape, roller bale contact pressure, etc. appropriate as the actual winding conditions, a robust and high-quality, unwinding package can be obtained. The relationship between the yarn spreading ratio x [%] and the twill angle w [°] of the innermost layer of the package is 300 <x · w <3000, preferably 900 <x · w <2500, more preferably 1000 <x · w <2400. The present inventors have found that a more stable unwinding property can be obtained by setting a certain range of the twill angle with respect to the yarn spreading rate so as to be in the above range.

  The innermost layer of the package is the angle between the carbon fiber 1 and the horizontal axis 5 when the bobbin axis 4 is vertical as shown in FIG. 3, in other words, the bobbin starts to wind the yarn. It is the angle with the insertion direction of the carbon fiber with respect to the rotation direction of the bobbin at the time.

  If x · w is 300 or less, the yarn will be wound in multiple layers, so even a slight force when pulling the yarn may pull out two or three yarns all at once. May become tangled and cannot be solved. On the other hand, if x · w is 3000 or more, the yarn moving speed in the axial direction is high at the time of high-speed unwinding.

  Further, the winding diameter a and the winding width b (6 and 7 in FIG. 4 respectively) of the carbon fiber package shown in FIG. 4 are 0.5 ≦ a / b ≦ 3, preferably 0.5 <a / b. By taking up so as to satisfy the relationship of <3, it is possible to improve the internal take-off property. When a / b is less than 0.5, the winding width with respect to the winding diameter increases, so that the contact area between the yarn drawn from the inner layer and the inner layer surface increases, and the fluff is generated by being easily rubbed, or the yarn bundle May get tangled and reduce the quality of the product. Further, if a / b exceeds 3, winding may be lost and the aesthetic appearance of the package form may be impaired, or fluff may occur due to unwinding failure due to winding collapse. Preferably better unraveling properties can be obtained by setting the range of 0.6 ≦ a / b ≦ 2.0, more preferably 0.7 ≦ a / b ≦ 1.5.

The effect of the carbon fiber removal and unwinding package of the present invention and the winding method thereof will be described with reference to examples and comparative examples.
(Examples 1-5, Comparative Examples 1-3)
In Examples 1 to 5 and Comparative Examples 1 to 3, all of the filaments were 12,000 filaments, and substantially untwisted and tape-shaped carbon fibers were used. The bobbin used was the spiral perforated paper tube shown in FIG. 1, and the package inner diameter after removing the paper tube was 80 mm, and the winding speed was 10 m / min. Polyacrylonitrile filaments obtained by dry and wet spinning are fired, the average single fiber diameter of the single fibers constituting the carbon fiber bundle is 7 μm, the ratio Sr / Sp of the actual surface area Sr to the projected area Sp is 1.01, and the tensile strength A carbon fiber bundle of 4900 MPa and a tensile modulus of 230 GPa was applied to the surface of the carbon fiber by applying a bisphenol A type epoxy resin sizing agent having a different SZ softening point to the surface of the carbon fiber while adjusting the SZ adhesion amount. Obtained.

For each of the Examples and Comparative Examples, the obtained carbon fiber bundles and the packages thereof have the following yarn spread rate, package form (winding length, winding width, twill angle), Sr / Sp, SZ softening point, SZ adhesion amount Table 1 shows the unwinding property, fuzziness, and resin impregnation property.
(Examples 6 to 20)
In Examples 6 to 20, all of the number of filaments was 12,000, and substantially twist-free and tape-shaped carbon fibers were used. The bobbin used was the spiral perforated paper tube shown in FIG. 1, and the package inner diameter after removing the paper tube was 80 mm, and the winding speed was 10 m / min. The polyacrylonitrile filaments obtained by dry and wet spinning are fired, the average single fiber diameter of the single fibers constituting the carbon fiber bundle is 7 μm, the ratio Sr / Sp of the actual surface area Sr to the projected area Sp is 1.02, and the tensile strength A carbon fiber bundle of 4900 MPa and a tensile modulus of 230 GPa was applied to the surface of the carbon fiber by applying a bisphenol A type epoxy resin sizing agent having a different SZ softening point to the surface of the carbon fiber while adjusting the SZ adhesion amount. Obtained.

  In Examples 19 and 20, the polyacrylonitrile filaments obtained by setting the bath draw ratio in the yarn making step to 0.7 times and 1.7 times, respectively, compared with the carbon fibers used in Examples 6 to 18 were fired. What was obtained was used.

  About each Example, about the obtained carbon fiber bundle and its package, the following yarn spread ratio, package form (winding length, winding width, twill angle), Sr / Sp, SZ softening point, SZ adhesion amount, unraveling Table 1 shows the properties, fluff and resin impregnation properties.

Next, the measurement method used in the present invention will be described.
<Winding diameter and winding width>
The package part shown in FIG. 4 is measured to the first decimal place using a caliper and expressed in mm.
<Yarn breaking rate>
Two fiber bundles cut to a length of about 20 mm are prepared. The test apparatus uses a packaging force tester (manufacturer name: Daiei Kagaku Seisakusho Co., Ltd. Model: TM200i, reciprocating speed 100 times / min). The cut fiber bundle is attached to the fixture so that it protrudes by 10 mm long, and the maximum yarn width at the tip of the fiber bundle using a parallel light line sensor (manufacturer name: OMRON Model: Z4LC-S2840, round bar diameter measurement mode) Is measured (the width is A). Thereafter, the two fixtures are set on a testing machine so that the fiber bundles fixed to each other overlap each other by 5 ± 0.5 mm in the fiber length direction. When the fiber bundle fixed to the moving-side fixing tool moves with a stroke of 13.5 mm on both sides around the position of the other fiber bundle fixed to the fixing-side fixing tool, it is fixed to each fixing tool. Fiber bundles collide with each other (5mm each). The number of times of movement, that is, the number of times of reciprocating the distance of 27 mm is 5 times, and the speed of reciprocating movement is 100 times / minute. After the reciprocating motion, the maximum yarn width B at the tip of the yarn bundle is measured with a parallel light line sensor in the same manner as the yarn width A, and the yarn spread rate (%) is defined as B / A × 100 to evaluate the yarn spread rate. (FIG. 5). The number of measurements is n = 20 (10 fixed to the moving side fixture and 10 fixed to the fixed side fixture), and is simply averaged.
<Aya corner>
The carbon fiber is peeled off from the carbon fiber package to the innermost layer, and the angle between the carbon fiber 1 and the horizontal axis 5 when the axis 4 of the bobbin stands upright as shown in FIG. 3 is measured with a protractor.
<Sr / Sp>
The ratio Sr / Sp between the actual surface area Sr and the projected area Sp is measured as follows. That is, the carbon fiber bundle was cut into a length of several mm, and single fibers were extracted. Next, a single fiber is fixed on a silicon wafer using a silver paste, and an image of a three-dimensional surface shape is obtained using an atomic force microscope, for example, a Dimension 3000 stage system of a Digitalscopes Nanoscope IIIa atomic force microscope. . The scanning mode is a tapping mode, and for example, an Olympus Optical Co., Ltd. Si cantilever integrated probe OMCL-AC120TS is used. The scanning speed is 0.4 Hz, the number of pixels is 512 × 512, and the measurement atmosphere is 25 ± 2 ° C. air. Next, the obtained image is subjected to data processing using the software Nanoscope III version 4.22r2 attached to the atomic force microscope, filtered using a first order filter, a lowpass filter, and a third order plane fit filter. The actual surface area Sr and the projected area Sp are calculated for the entire obtained image, and the ratio thereof, that is, Sr / Sp is obtained. Note that the projected area is a projected area on a cubic curved surface that approximates the curvature of the curved surface, considering that the single fiber has a curved surface. And the said measurement is performed about five places arbitrarily selected about one single fiber, and let the ratio Sr / Sp be the arithmetic mean value of three places except the maximum value and the minimum value. The number of n in the Sr / Sp measurement is 3, and is determined as a simple average value.
<SZ softening point>
The SZ softening point is measured as follows. That is, the sizing agent is dried at 100 ° C. for 2 hours to obtain a dried product. The flow start temperature of the dried product is measured using a Koka flow tester under the conditions of orifice inner diameter / length = 1 mm / 1 mm, load = 9.8 N, heating rate = 3 ° C./min. The n number is 3, and the simple average value is calculated as the softening point.
<SZ adhesion amount>
The SZ adhesion amount is measured as follows. That is, a carbon fiber bundle having a weight of 1 g (2 g) is placed in a 450 ° C. electric furnace (capacity: 120 cm ³ ) in which nitrogen gas is flowed at 50 liters / minute so as not to be exposed to air, and left for 15 minutes. The sizing agent is completely pyrolyzed. Next, it is transferred into a container in which 20 liters / minute of dry nitrogen gas is flowing, and after cooling for 15 minutes, the weight W2 g is measured and obtained from the following equation.

SZ adhesion amount (%) = ((W1-W2) / W1) × 100
<Number of unsuccessful unraveling>
In the present invention, the number of unsuccessful unwinding times shown below is used as an index relating to the unwinding property of the carbon fiber package. That is, the number of unwinding failures that cannot be pulled out of the package due to the occurrence of mixed fibers or ring-shaped fluff when a package placed on a vertical floor is unwound for 30 minutes at a unwinding speed of 70 m / min with a distance to the guide of 1.0 m. And the number of unwinding defects per 10 km [times / 10 km] is calculated.
<Number of fuzz>
In the present invention, the number of fuzz shown below is used as an index relating to the quality of the carbon fiber. That is, the yarn unwound at 70 m / min is rewinded on a bobbin, and the carbon fiber package as an evaluation sample is placed in a temperature control room controlled at a temperature of 23 ± 3 ° C. and a relative humidity of 60 ± 5% for 60 minutes or more. put. Next, using the fluff counting device in the temperature control chamber where the temperature and humidity conditions are set, according to the yarn path diagram shown in FIG. 9, the carbon fiber is put on the creel 13 incorporating the powder clutch, and the yarn path And pass through the fluff counter 14. The fluff counter is a device that detects the number of fluff using a phototransistor while irradiating the running yarn from lamp light and condensing the irradiated light with a lens. As detection accuracy, fluff having a yarn length of 2 mm or more and a carbon fiber single fiber diameter of 3 μm or more can be detected. The carbon fiber is wound around the drive roller 15 five times or more and wound around the winder 16 so as not to cause a slip during traveling. The yarn speed is set to 3 m / min, and the carbon fiber travel is started on the yarn path through the roller 17 shown in FIG. After confirming that the yarn path is stable, the initial tension is adjusted with the powder clutch so that the tension of the carbon fiber during running measured between the fluff counting device 14 and the driving roller 15 becomes 6 gf / tex. Thereafter, the fluff counter is operated, and the fluff evaluation in the running state is measured for 30 m for each sample, and the number of fluff per 1 m [pieces / m] is calculated. In this example, a fluff number counting device “DT-105 (S special)” manufactured by Toray Engineering Co., Ltd. was used as the fluff number counting device.
<Resin pickup rate>
In the present invention, the following resin pickup rate is used as an index relating to the resin impregnation property of carbon fiber. That is, 3 bundles of 250 mm long carbon fiber bundles with 2400-3300 tex as one bundle are combined, and one end of the bundle is left 50 mm. A portion of 30-50 mm above the knot is fixed with tape, and the yarn bundle is cut accurately at 150 mm from below the knot. A braided sample is produced by knitting three yarn bundles as shown in FIG. The number of times of knitting is set to 35 times. The number of braids is counted once by inserting one bundle between two bundles, and then counting twice and three times sequentially. The carbon fiber bundle of 800-1700 tex same as the sample is used as shown in FIG. 7 so that the tail portion is not unraveled after being knitted 35 times. Make sure that the length of the knot and the braid part inside the knot is 100-110 mm (do not use as a sample if it is outside this range), peel off the tape that has been fixed, and on the upper knot Cut the 20mm part. The braid sample weight thus prepared is measured with an electronic balance up to the fourth decimal place (referred to as C). As the resin for resin impregnation, bisphenol A type epoxy resin (Epicoat 827: manufactured by Japan Epoxy Resin Co., Ltd.) having an average molecular weight of 370 is used. At room temperature 50 ° C, a 500 g weight is attached to the knot portion under the braid with a clip (Fig. 8), the upper end 10 mm of the knot is held with a pliers, and the entire sample is placed in a container containing epoxy resin for 5 seconds. Immerse. Then, pull it up quickly and leave it in the air for 10 seconds. After that, quickly remove the clip and weight, place the sample on an aluminum pan, and measure the weight with the electronic balance to the fourth decimal place. When the weight after resin impregnation is D, the resin pickup rate (%) is calculated from the following equation. The number of measurements is n = 10 and a simple average is performed.

      Resin pickup rate (%) = (D−C) / C × 100

Example of drawing out bobbin from internal bobbin (spiral perforated bobbin) Illustration of vertical ballooning from the outer layer Twill angle explanatory drawing Explanation of winding diameter and winding width of carbon fiber package Yarn break rate measurement chart Braiding method and count method explanatory diagram Illustration of how to tie braid ends Resin pickup rate measurement chart Fluff counting device diagram

Explanation of symbols

1 carbon fiber 2 guide 3 perforation 4 axis 5 horizontal axis 6 roll diameter 7 roll width 8 fixture 9 knot 10 carbon fiber 11 weight 12 resin 13 creel 14 fluff counter 15 drive roller 16 winder 17 roller

Claims (3)

A carbon fiber package in which a yarn satisfying the following formula (1) with a yarn breaking rate x [%] is wound around a bobbin for taking up and unwinding.
100 <x <150 (1) The carbon fiber package according to claim 1, wherein the carbon fiber package is wound so that the yarn spreading ratio x [%] and the innermost wavy angle w [°] of the package satisfy the following formula (2).
300 <x · w <3000 (2) The carbon fiber package of Claim 1 or Claim 2 wound up so that the winding diameter a and the winding width b may satisfy | fill the following formula | equation (3).
0.5 ≦ a / b ≦ 3 (3)

Images