WO2020203390A1

WO2020203390A1 - Carbon-fiber-precursor fiber bundle and method for producing same

Info

Publication number: WO2020203390A1
Application number: PCT/JP2020/012605
Authority: WO
Inventors: 伊原康樹; 林田賢吾; 大隈崇裕
Original assignee: 東レ株式会社
Priority date: 2019-03-29
Filing date: 2020-03-23
Publication date: 2020-10-08
Also published as: JPWO2020203390A1; TW202041731A

Abstract

Provided is a carbon-fiber-precursor fiber bundle obtained by combining a plurality of at least two flat carbon-fiber-precursor filaments, wherein: a degree of interlacement of the carbon-fiber-precursor filaments as determined by the hook drop method is 5 to 23; a yarn width X of the carbon-fiber-precursor fiber bundle with respect to a yarn width W of the carbon-fiber-precursor filaments is within a range of W ≤ X ≤ 2.2W; and the carbon-fiber-precursor filaments are arranged in the carbon-fiber-precursor fiber bundle in such a manner that 0.5 to 5 continuous clockwise turns and 0.5 to 5 continuous counterclockwise turns about a longitudinal central axis of the carbon-fiber-precursor fiber bundle as a turning axis are alternately repeated. By using the carbon-fiber-precursor fiber bundle according to the present invention, it is possible to increase a filament density during a baking step, making it possible to obtain a high-grade and high-quality carbon fiber at a low cost.

Description

Carbon fiber precursor fiber bundle and its manufacturing method

The present invention relates to a carbon fiber precursor fiber bundle capable of dividing a fiber bundle having a large number of filaments into a plurality of fiber bundles having a small number of filaments, and a method for producing the same.

Carbon fiber has been used as a reinforcing fiber for fiber-reinforced composite materials because of its high specific strength and specific elastic modulus, and has contributed to the weight reduction of aircraft. In recent years, this trend has been accelerating, and the number of applicable members is expanding and the application to large members is being promoted. Further improvement of mechanical properties centering on the strand elastic modulus, and stable machinery as carbon fiber. Expression of specific characteristics is required.

In recent years, in addition to conventional aircraft applications and sports applications, the scope of application is expanding more and more to industrial applications such as automobiles, wind turbines, pressure vessels, and electronic device housings. In industrial applications, while maintaining the high mechanical properties of carbon fiber, economic efficiency equivalent to that of current materials such as metal materials and glass fiber reinforced composite materials is required. In order to meet the needs, it is desired not only to reduce the cost of expensive carbon fibers but also to reduce the weight of structural members (reduce the amount of members used) by further improving the mechanical properties of carbon fibers. Therefore, it is important to improve the tensile strength of the carbon fiber that controls the mechanical properties of the carbon fiber reinforced composite material.

Polyacrylonitrile-based precursor fiber bundles are widely known as carbon fiber precursor fiber bundles. For carbon fibers, for example, a polyacrylonitrile-based precursor fiber bundle, which is the precursor fiber bundle, is once wound up in a yarn-making process to form a package, and then the precursor fiber bundle is unwound from the package to form a polyacrylonitrile-based precursor fiber bundle. Is converted into flame-resistant fibers in an oxidizing atmosphere of 200 to 300 ° C., and the flame-resistant fibers are further heated to 300 to 3000 ° C. in an inert atmosphere such as nitrogen, argon or helium to be carbonized. Obtained by going through a carbonization process. As another method, the precursor fiber bundle obtained in the silk reeling process is stored in a kens or the like without being wound up, and the carbon fibers are produced by the same process after unwinding them. The most widely used polyacrylonitrile-based carbon fibers are mainly so-called regular tow type carbon fibers of 1000 to 24000 filaments with excellent quality with less yarn breakage and fluffing, and are used as reinforcing fibers for composite materials. It is widely used for sports and aerospace applications, mainly for general industrial applications. Providing low-cost, high-quality carbon fibers is an important issue for further expansion of applications, and even in the manufacturing process of carbon fiber precursor fiber bundles, many improvements have been made regarding cost reduction by improving production efficiency. The technology is disclosed.

For example, in

Patent Documents

1 and 2, as a method for efficiently producing carbon fibers having a small number of filaments, after imparting convergence to carbon fiber precursor threads, a plurality of carbon fiber precursor threads are combined. Therefore, a method of forming a carbon fiber precursor fiber bundle having a large number of filaments has been proposed. Patent Document 3 describes a technique in which adjacent carbon fiber precursor yarns are subjected to air entanglement treatment, stored as one carbon fiber precursor fiber bundle having a large number of filaments, and divided by applying tension to the fiber bundle. Has been proposed. Patent Document 4 proposes a technique in which a carbon fiber precursor fiber bundle is subjected to air entanglement treatment to impart convergence, and then wound into a single bobbin without being aligned.

JP-A-9-273032 JP-A-58-87321 International Publication No. 2005/078773 JP-A-2010-1597

However, in the method of combined yarn disclosed in Patent Document 1, the control of the overlapping state of the carbon fiber precursor yarns is insufficient, and the carbon fiber precursor yarns are entangled with each other. There are problems such as yarn breakage of carbon fiber precursor fiber threads due to fluffing.

Further, in the method of combined yarn disclosed in Patent Document 2, since it is necessary to twist and twist each carbon fiber precursor fiber yarn, it is necessary to perform untwisting, which increases the equipment cost and also increases the equipment cost. There was a concern that the yarn width would become unstable due to the effect of untwisted yarn.

Further, in the combined yarn method disclosed in Patent Document 3, since the carbon fiber precursor yarns are arranged in parallel, it is difficult to increase the yarn density, which is insufficient to improve the productivity. It was. Further, there is a problem that the storage method of the carbon fiber precursor fiber bundle is also limited to Kens.

Further, in the yarn combining method disclosed in Patent Document 4, since the yarn is combined after being carbonized, the effect of increasing the thread density is not always sufficient.

Patent Documents

1 and 2 focus on the ease of division of the carbon fiber precursor yarn by imparting convergence, and do not focus on the arrangement of the carbon fiber precursor yarn after the combined yarn. On the other hand,

Patent Documents

3 and 4 focus on the arrangement of carbon fiber precursor threads, but they are limited to the arrangement in parallel, so that they are insufficient to increase the thread density.

The present invention has been made to solve such a conventional problem, and by combining a plurality of carbon fiber precursor yarns, the yarn density is increased and the carbon fiber precursor yarns are entangled with each other. It is an object of the present invention to provide a carbon fiber precursor fiber bundle which is controlled, is less likely to cause fluff and yarn breakage, and can be easily divided.

In order to achieve the above problems, the carbon fiber precursor fiber bundle of the present invention has the following characteristics.

That is, it is a carbon fiber precursor fiber bundle formed by combining a plurality of flat carbon fiber precursor threads, and the degree of entanglement required by the hook drop method of the carbon fiber precursor threads is 5 or more and 23 or less. Yes, the thread width X of the carbon fiber precursor fiber bundle is within the range of W ≦ X ≦ 2.2 W with respect to the thread width W of the carbon fiber precursor thread, and in the carbon fiber precursor fiber bundle, The carbon fiber precursor filament alternates between 0.5 rotations or more and 5 rotations or less continuous right rotation and 0.5 rotations or more and 5 rotations or less continuous left rotation with the central axis in the longitudinal direction of the carbon fiber precursor fiber bundle as the rotation axis. It is a carbon fiber precursor fiber bundle arranged so as to repeat.

Further, the method for producing a carbon fiber precursor fiber bundle of the present invention has the following constitution.

That is, it is a method for producing a carbon fiber precursor fiber bundle by combining a plurality of carbon fiber precursor threads to obtain a carbon fiber precursor fiber bundle, wherein the carbon fiber precursor threads are flat and hook. When the degree of entanglement required by the drop method is 5 or more and 23 or less and the thread width of the carbon fiber precursor threads is W, the width Y of the flat portion of the plurality of carbon fiber precursor threads is W ≦ Y. On the flat portion of the grooved guide roller within the range of ≦ 2.2 W, the carbon fiber precursor fibers are combined by stacking them in layers to form a carbon fiber precursor fiber bundle, and then the carbon fiber precursor is used using a plurality of thread path regulating members. By skewing the body fiber bundle, rotation is imparted to the carbon fiber precursor fibers in the carbon fiber precursor fiber bundle, and the carbon fiber precursor threads form the central axis in the longitudinal direction of the carbon fiber precursor fiber bundle. The carbon fiber precursor fiber bundle in which the thread path regulating member is arranged so as to alternately repeat continuous clockwise rotation of 0.5 rotation or more and 5 rotations or less and continuous left rotation of 0.5 rotation or more and 5 rotations or less as a rotation axis. It is a manufacturing method of.

According to the present invention, a plurality of carbon fiber precursor fibers are combined into one carbon fiber precursor fiber bundle, wound on a bobbin, or stored in a kens, and then from the carbon fiber precursor fiber bundle. It is possible to provide a carbon fiber precursor fiber bundle which is less likely to cause fluff and thread breakage and can be divided into the original carbon fiber precursor thread units, and a method for producing the same. By using the carbon fiber precursor fiber bundle of the present invention, the yarn density can be increased in the firing step, so that high-quality and high-quality carbon fibers can be obtained at low cost.

It is a schematic diagram which shows the state in which three carbon fiber precursor yarns rotate clockwise about the central axis of the carbon fiber precursor fiber bundle in the longitudinal direction as a rotation axis. It is a schematic diagram which shows the state in which three carbon fiber precursor yarns rotate counterclockwise about the central axis in the longitudinal direction of a carbon fiber precursor fiber bundle as a rotation axis. It is a simplified figure which shows an example of the combined yarn process which concerns on this invention. It is a simplified figure which shows the oblique thread path of a carbon fiber precursor fiber bundle. It is a schematic diagram which shows the case where one carbon fiber precursor yarn takes an arrangement which intersects with other carbon fiber precursor yarns in the measurement of the number of rotations in three carbon fiber precursor yarns. It is a schematic diagram which shows the case where one carbon fiber precursor thread is arranged so as to sew the other thread in the measurement of the number of rotations of three carbon fiber precursor threads. In the measurement of the number of rotations of the three carbon fiber precursor threads, the case where the central axis of the carbon fiber precursor fiber bundle is rotated and arranged independently of the rotation axis is shown. It is a schematic diagram. It is a schematic diagram which shows a mode that continuous clockwise rotation and continuous counterclockwise rotation are introduced alternately by a diagonal thread path. It is a schematic diagram which shows the mode that the paired right rotation is introduced when the left rotation is given between two points held in a flat shape.

In the present invention, the fiber bundle after combining a plurality of carbon fiber precursor yarns is described as a carbon fiber precursor fiber bundle, and the fiber bundle is before the yarn is combined or after the yarn is once combined and further divided. Is described as carbon fiber precursor yarn to distinguish it.

The embodiment of the present invention will be described in detail.

The type of the polymer constituting the carbon fiber precursor fiber bundle of the present invention is not particularly limited, but it is preferably an acrylic polymer mainly composed of acrylonitrile, and specifically, 90% by mass or more of acrylonitrile and another copolymer 10 It is preferably a copolymer composed of% by mass or less. The comonomer includes carboxylic acids such as acrylic acid, methacrylic acid and itaconic acid, and alkyl esters such as their methyl esters, ethyl esters, propyl esters and butyl esters; their alkali metal or ammonium salts, or allyl sulfonic acids. Examples thereof include sulfonic acids such as metallic sulfonic acid and styrene sulfonic acid, and alkali metal salts thereof, but the present invention is not particularly limited. If the copolymerization ratio of the comonomer exceeds 10% by mass, the physical properties of the finally obtained carbon fiber may deteriorate. The acrylic polymer can be polymerized by using a usual polymerization method such as emulsion polymerization, bulk polymerization or solution polymerization.

Next, a method for producing a carbon fiber precursor fiber bundle will be described.

A conventional wet spinning method or a conventional wet spinning method or the like using a polymer solution consisting of the above acrylic polymer and an organic solvent such as dimethylacetamide, dimethylsulfoxide, dimethylformamide; an aqueous solution of an inorganic substance such as nitrate, zinc chloride, rodane soda, etc. After spinning by a dry-wet spinning method to obtain a coagulated yarn, the obtained coagulated yarn is drawn in a bath. In this in-bath drawing step, the coagulated yarn is usually drawn in a drawing bath at 30 to 98 ° C. about 2 to 6 times to obtain a drawn yarn. It should be noted that preferably, the drawn yarn is washed with water after drawing in the bath, or the coagulated yarn is washed with water and then drawn in the bath to remove the residual solvent in the drawn yarn to the extent that there is no problem. The drawn yarn after being drawn in the bath is dried and densified by a hot roller or the like after being applied with an oil agent to become carbon fiber precursor yarns. Further, if necessary, a secondary stretching step such as steam stretching and a step of imparting convergence can be further carried out. In order to impart convergence, a general method such as a method of passing the carbon fiber precursor yarn through the grooved guide roller or a method of gas entanglement treatment can be selected. The step of imparting convergence does not necessarily have to be arranged after the drying densification step or the secondary drawing step, and can be carried out at any stage of the silk reeling step. In addition, the convergence of the carbon fiber precursor yarn can be measured by the hook drop method as follows. In the present invention, the degree of entanglement required by the hook drop method of the carbon fiber precursor yarn is 5 or more and 23 or less, preferably 7 or more and 20 or less, and more preferably 7 or more and 15 or less.

<Confounding degree by hook drop method>
The degree of entanglement of the carbon fiber precursor yarn by the hook drop method is measured according to the method of measuring the degree of entanglement in JIS-L1013 (2010) “Chemical fiber filament yarn test method”. A load of 100 g is hung at a position below the carbon fiber precursor yarn obtained by dividing the carbon fiber precursor fiber bundle, and the yarn is hung vertically. A hook with a load of 10 g is inserted into the upper part of the thread, and the degree of entanglement is calculated from the descent distance (mm) until the hook stops due to entanglement of the threads by the following formula. Measure 50 times and calculate the average value. All the carbon fiber precursor yarns constituting the carbon fiber precursor fiber bundle were measured, and the average value was taken as the degree of entanglement.
Confounding degree = 1000 / hook descent distance.

The carbon fiber precursor fiber bundle of the present invention can be obtained by combining a plurality of carbon fiber precursor yarns imparted with such convergence on a guide roller. The carbon fiber precursor fiber bundle can then be wound into a package by a winder or stored in Kens. The single fiber fineness of the carbon fiber precursor yarn is preferably 0.5 to 3.3 dtex. By setting the single fiber fineness to 0.5 dtex or more, stable operability can be ensured. By setting the single fiber fineness to 3.3 dtex or less, it is possible to suppress spot burning in the flame resistance step and to develop high tensile strength. The number of filaments of the carbon fiber precursor yarn is preferably 1000 or more and 24,000 or less, and more preferably 3000 or more and 12000 or less. When the number of filaments exceeds 24,000, it is difficult to impart uniform entanglement to the entire filament, and harsh conditions must be adopted when imparting the required entanglement. Therefore, the carbon fiber precursor The fluff of the threads may increase or the threads may break. The number of combined yarns of the carbon fiber precursor yarn is preferably 2 or more and 10 or less, and more preferably 3 or more and 8 or less. If the number of combined yarns exceeds 10, when dividing the fiber bundle, it is necessary to newly install a yarn width regulation guide for division, a take-up machine, etc. during the process, and the manufacturing cost becomes rather high. There's a problem.

Next, the combined yarn state of the carbon fiber precursor yarns in the carbon fiber precursor fiber bundle of the present invention will be described in detail. The yarn width X of the carbon fiber precursor fiber bundle of the present invention obtained by combining a plurality of carbon fiber precursor yarns is W ≦ X ≦ 2 with respect to the yarn width W of the carbon fiber precursor yarns. It is within the range of .2W. When the yarn width X of the carbon fiber precursor fiber bundle is smaller than the yarn width W of the carbon fiber precursor yarn, the flatness is lost such as the carbon fiber precursor yarn being folded, and the carbon fiber precursor after division is lost. The variation in the thread width of the body fibers increases. When the yarn width X of the carbon fiber precursor fiber bundle exceeds 2.2 W, the carbon fiber precursor yarns are arranged when the carbon fiber precursor fiber bundle is unwound from the bobbin or Kens and guided to the guide roller group. Since the carbon fiber precursor yarns are entangled with each other freely, fluff may increase or yarn breakage may occur at the time of division.

<Measurement of yarn width X of carbon fiber precursor fiber bundle and yarn width W of carbon fiber precursor yarn>
The carbon fiber precursor fiber bundle obtained by the above method was wound on a bobbin or stored in a kens, and then the carbon fiber precursor fiber bundle was unwound and cut to a length of 5 m. For the carbon fiber precursor fiber bundle, the yarn widths at 10 points were measured at different positions in the longitudinal direction, and the average value was defined as the yarn width X. Further, a 5 m carbon fiber precursor fiber bundle was divided so as not to lose its shape to obtain carbon fiber precursor threads. For each of the obtained carbon fiber precursor yarns, the yarn width was measured at 10 points at different positions in the longitudinal direction in the same manner as in the carbon fiber precursor fiber bundle, and the average of the points (number of combined yarns × 10) was the yarn width W. And said. At that time, when the carbon fiber precursor yarn was folded, the folded portion was returned to form a flat yarn, and then the yarn width was defined as the yarn width W.

Further, in the carbon fiber precursor fiber bundle of the present invention, the arrangement of the plurality of combined carbon fiber precursor fibers is 0.5 rotations with the central axis in the longitudinal direction of the carbon fiber precursor fiber bundle as the rotation axis. It exists so as to alternately repeat continuous clockwise rotation of 5 rotations or more and continuous left rotation of 0.5 rotations or more and 5 rotations or less. Here, the clockwise rotation and the counterclockwise rotation are the rotation directions given when the line of sight is placed in the same direction as the traveling direction A of the carbon fiber precursor fiber bundle, as shown in FIGS. 1 and 2, respectively.

FIG. 1 shows an example in which the carbon

fiber precursor threads

1, 1 ′, 1 ″ rotate clockwise with the central axis 3 in the longitudinal direction of the carbon fiber precursor fiber bundle 2 as the rotation axis. .. Further, FIG. 2 shows an example in which the carbon

fiber precursor threads

1, 1 ′, 1 ″ rotate counterclockwise with the central axis 3 in the longitudinal direction of the carbon fiber precursor fiber bundle 2 as the rotation axis. ing. If the rotation direction is only one direction, for example, the rotation is in the right direction, the twists continue to accumulate when the carbon fiber precursor fiber bundle is divided, and the carbon fiber precursor fiber bundle cannot be divided after being unwound for a certain length.

Further, the maximum continuous rotation speed in any of the clockwise and counterclockwise rotations of the carbon fiber precursor thread is 0.5 rotations or more and 5 rotations or less, preferably 0.5 rotations or more and 4 rotations or less, and further. It is preferably 0.5 rotations or more and 2 rotations or less. If the maximum continuous rotation speed is less than 0.5 rotations, the convergence of the carbon fiber precursor fiber bundle becomes insufficient, and a plurality of layers are stacked when passing through the yarn-making process or unwinding from the bobbin or Kens. Since the arrangement of the carbon fiber precursor yarns is freely exchanged and the carbon fiber precursor yarns are entangled with each other, fluff increases and yarn breakage occurs at the time of division. In addition, one or several of the plurality of carbon fiber precursor yarns may be separated during passing through the silk reeling process or when the bobbin or Kens is unwound, resulting in unstable process passability. is there. On the other hand, when the maximum continuous rotation speed exceeds 5 rotations, the presence of an excessive entangled portion may cause the carbon fiber precursor yarns to rub against each other during division and cause fluffing.

<Determination of continuous clockwise and counterclockwise rotation of carbon fiber precursor yarn and measurement of maximum continuous rotation speed>
One end of the carbon fiber precursor fiber bundle is divided into constituent precursor fiber yarn units and fixed so that the stacking order of the precursor fiber yarns can be identified (hereinafter referred to as fixing point 1). Subsequently, the fixing point 1 is pulled out from the bobbin or Kens by 3 m and fixed so that the stacking order of the precursor fiber threads constituting the carbon fiber precursor fiber bundle can be identified (hereinafter referred to as the fixing point 2). It has a fixed point 1, and the line of sight is placed in the direction opposite to the unwinding direction (bobbin or Kens direction), and the central axis in the longitudinal direction is the rotation axis, and the plurality of entwined carbon fiber precursor threads are each thread unit. Rotate the carbon fiber precursor fiber bundle until split into. Regarding the number of rotations required at that time, 180 ° rotation is made by distinguishing between right rotation and left rotation, and 0.5 rotation when 180 ° rotation is required and 1.0 rotation when 360 ° rotation is required. Each rotation is counted as 0.5 rotation, and the number of rotations introduced between the fixed point 1 and the fixed point 2 is measured. If there is no rotation, it is set to 0 rotation. Subsequently, a carbon fiber precursor fiber bundle of 3 m is further drawn from the fixed point 2 in the measurement, and the rotation speed is measured by the same method. When the rotation direction is the same as the immediately preceding measurement and when the rotation is 0, the measurement is continued in the same rotation direction, and the obtained rotation speeds are integrated. If the rotation directions are different, the counting of the number of rotations in the immediately preceding rotation direction is finished, and the counting in the new rotation direction is started. The number of rotations accumulated until the directions of rotation are different is taken as the continuous number of rotations of the carbon fiber precursor yarn. As shown in FIG. 5, one or a plurality of carbon fiber precursor threads 1 may be arranged so as to cross the other carbon fiber precursor threads 1', 1'' from one direction. .. In this case, the rotation speed when the number of crossings of the carbon fiber precursor yarn is minimized is adopted. Further, as shown in FIG. 6, one carbon fiber precursor thread 1 is arranged so as to sew another carbon fiber precursor thread 1', 1'', or as shown in FIG. 7 as an example. As described above, when the carbon fiber precursor threads 1 ′ and 1 ″ are arranged to rotate independently of the rotation by the central axis of the carbon fiber precursor fiber bundle 2, the measurement is continued as 0 rotation. .. If the arrangement in which the rotation direction cannot be determined is confirmed twice in a row, the continuous rotation speed cannot be measured and the measurement is terminated.

The measurement is carried out until the continuous rotation speed in the right direction (hereinafter referred to as continuous clockwise rotation) and the continuous rotation speed in the left direction (hereinafter referred to as continuous counterclockwise rotation) introduced into the carbon fiber precursor yarn can be measured 10 times each. repeat. The maximum value of the continuous rotation speed in each of the left direction and the right direction obtained by measuring the measurement from five different points in the longitudinal direction of the carbon fiber precursor fiber bundle is defined as the maximum continuous rotation speed.

Next, the details of the yarn combination method will be explained.

In the present invention, two or more flat carbon fiber precursor yarns having a yarn width W are guided and combined in a layered manner on a grooved guide roller. Here, the flat shape means a flat tape-like shape having a width larger than a thickness. The thickness / width ratio range is preferably 0.0001 to 0.3. By setting the thickness / width to 0.3 or less, it is possible to secure a sufficient contact surface between the carbon fiber precursor yarns in the yarn combining process, and it is possible to maintain a state in which the yarns are layered. .. The flat carbon fiber precursor yarn can be obtained by holding the substantially untwisted carbon fiber precursor yarn on a flat flat roller.

FIG. 3 shows an example of a preferable mode of the yarn combining method of the present invention. The grooved guide roller 4 has a flat groove (hereinafter referred to as a flat portion), and two or more carbon fiber precursor threads 1, 1', 1'' are layered on the flat portion. It is held in a state of being sent to the next thread path regulating member 5. The width Y of the flat portion is within the range of W ≦ Y ≦ 2.2 W with respect to the yarn width W of the carbon fiber precursor yarn. When the width Y of the flat portion is smaller than W, the carbon fiber precursor threads cannot be stacked in layers, the carbon fiber precursor threads are folded on the guide, and the flatness is lost. In addition, the arrangement of the carbon fiber precursor threads is freely exchanged on the guide, and the carbon fiber precursor threads are entangled. When the width Y of the flat portion exceeds 2.2 W, two precursor threads are lined up side by side on the guide, so that two or more precursor threads cannot be stacked in layers, and the same is on the guide. Tangles of carbon fiber precursor threads. Further, since one or a plurality of carbon fiber precursor yarns do not overlap in a layered manner, uniform rotation cannot be imparted to the entire carbon fiber precursor fiber bundle, and the convergence becomes insufficient. As a result, one or several of the carbon fiber precursor yarns are separated when the carbon fiber precursor fiber bundle obtained by the combined yarn is passing through the yarn making process or is unwound from the bobbin or Kens. As a result, the process passability becomes unstable.

Next, the carbon fiber precursor fiber bundles obtained by combining the yarns are skewed using a plurality of thread path regulating members to rotate the carbon fiber precursor fibers in the carbon fiber precursor fiber bundles. Give. At this time, the carbon fiber precursor threads continuously rotate clockwise from 0.5 rotations to 5 rotations and continuously from 0.5 rotations to 5 rotations with the central axis in the longitudinal direction of the carbon fiber precursor fiber bundle as the rotation axis. The arrangement of the plurality of thread path regulating members is adjusted so that the counterclockwise rotation and the counterclockwise rotation are alternately repeated. As an embodiment of imparting rotation to the carbon fiber precursor threads in the present invention, for example, as shown in FIG. 3, the carbon

fiber precursor threads

1, 1 ′, 1 ″ are attached to the grooved guide roller 4 for the combined yarn. After guiding and forming the carbon fiber precursor fiber bundle 2, the carbon fiber is passed through the thread path created by arranging a plurality of thread

path regulating members

5 and 6 along the traveling direction of the carbon fiber precursor fiber bundle 2. By skewing the precursor fiber bundle 2, the carbon fiber precursor fibers in the carbon fiber precursor fiber bundle are given rotation. Here, skewing means, as shown in FIG. 4, a thread path arranged so that the grooved guide roller 4 for combining threads and the carbon fiber precursor fiber bundle 2 passing through the grooved guide roller for combining threads travel straight. the straight line L ₁ obtained by connecting the center points of the restriction member 5 is obtained by the carbon fiber precursor fiber bundle running skew for the yarn path regulating member 6 provided behind the yarn path regulating member 5 linear The carbon fiber precursor fiber bundle 2 is run so that the angle θ formed by L ₂ (hereinafter referred to as an oblique angle θ) is 0.5 ° or more.

<Slanting angle θ of carbon fiber precursor fiber bundle>
As shown in FIG. 4, the skew angle θ (°) of the carbon fiber precursor fiber bundle is the thread path regulating member 5 and the thread path regulating member for skewing arranged along the traveling direction of the carbon fiber precursor fiber bundle. distance between 6 L (mm), and the vertical direction including the straight line L ₁ obtained by connecting the center points of the running portion of the carbon fiber precursor fiber bundle in doubling for grooved guide roller 4 and the yarn path regulating member 5 The length D (mm) of the perpendicular line from the oblique thread path regulating member 6 with respect to the plane of the above can be measured and calculated by the following formula.

θ = arcsin (D / L) × 360 ° ÷ 2π
The thread path regulating member used in the present invention changes the position of the carbon fiber precursor yarns constituting the carbon fiber precursor fiber bundle by obliqueing the traveling carbon fiber precursor fiber bundle by a physical external force. Anything that can be done is sufficient. The shape of the thread path regulating member includes a U-shape, a V-shape, an H-shape, a loop type, a snail type, a hook type, a pipe type, and the like, but the shape is not particularly limited. Specific examples of the thread path regulating member include a single guide, a comb guide, a single roller, and a groove roller having one or more grooves. The thread path regulating member is preferably selected from rollers such as a rotating single roller and a groove roller in order to prevent the carbon fiber precursor fiber bundle from being scratched. Further, there is no problem whether the thread path regulating member and the thread path regulating member for skewing use the same type or different types.

FIG. 8 shows a schematic diagram of the principle in which rotation is applied to the carbon fiber precursor fiber bundle. The first yarn path regulating member 5 is arranged so that the carbon fiber precursor fiber bundle 2 that has passed through the grooved guide roller 4 for the combined yarn goes straight. Then, the thread path regulating member 6 for skewing is arranged behind the thread path regulating member 5 so that the skew angle θ is 0.5 ° or more. In this arrangement, when moving the carbon fiber precursor fiber bundle 2, the carbon fiber precursor fiber bundle 2 at the point of skew for the yarn path regulating member 6, the tension T ₁ of the running direction, the traveling direction A component force T _{2 in the} vertical left direction is generated, and the carbon fiber precursor fiber bundle 2 tends to move in the vertical left direction in the traveling direction. Further, the frictional force F ₁ in the running direction vertical right direction between the carbon fiber precursor fiber bundle 2 and skew for the yarn path regulating member 6 acts. Therefore, the carbon fiber precursor fiber bundle 2 is provided with a continuous counterclockwise rotation B in the traveling direction. The maximum number of rotations of the left rotation that is continuously applied is not always fixed, but since the rotation is introduced until the torsional rigidity of the carbon fiber precursor fiber bundle 2 and the above-mentioned rotational force are balanced, the skew angle θ The maximum number of revolutions can be adjusted by adjusting.

FIG. 9 shows how a pair of clockwise rotations are imparted to the carbon fiber precursor fiber bundle 2 when a counterclockwise rotation is applied between two points held flat in the carbon fiber precursor fiber bundle 2. It is a schematic diagram. Illustrating the principle of imparting left-handed rotation and right-handed rotation according to the example of FIG. 8, the carbon fiber precursor fiber bundle 2 that has passed through the grooved guide roller 4 for synthetic yarn is used in the first yarn path regulating member 5. because it is held in flat, by friction friction force F ₁ generated between the skew for the yarn path regulating member 6 and the carbon fiber precursor fiber bundle 2 as described above, continuous counterclockwise rotation B imparted To. On the other hand, between the skewing thread path regulating member 6 and the second thread path regulating member 5, a force for introducing the same number of clockwise rotations C acts so as to cancel the introduced counterclockwise rotation. Since this force is the restoring force due to the torsional rigidity of the carbon fiber precursor fiber bundle 2, the rotation speed does not completely disappear and the left and right rotation speeds are not always equal. However, due to such a principle, carbon The fiber precursor fiber bundle 2 can be present so as to alternately repeat continuous clockwise rotation and continuous counterclockwise rotation.

The carbon fiber precursor fiber bundle thus obtained is wound on a bobbin or stored in a kens.

[Example 1]
Using dimethyl sulfoxide as a solvent, acrylonitrile and itaconic acid were copolymerized by a solution polymerization method to obtain a polymer solution containing polyacrylonitrile. Using this polymer solution as a spinning stock solution, a coagulated yarn was obtained by spinning into a coagulation bath consisting of an aqueous solution of dimethyl sulfoxide by a dry-wet spinning method. The coagulated yarn was washed with water and stretched in warm water, then immersed in an oil bath, and further dried and densified in a drying step. Subsequently, the carbon fiber precursor yarn was obtained by stretching in pressurized steam.

After air entanglement treatment is performed on each of the two substantially untwisted carbon fiber precursor yarns having 3000 filaments, the carbon fiber precursor yarns are gripped on a flat roller composed of flat portions. The flattening treatment was carried out to obtain a flat carbon fiber precursor yarn having a yarn width of 3.0 mm. Two of these flat carbon fiber precursor yarns were layered and combined on a grooved guide roller having a flat portion having a width of 3.0 mm. The carbon fiber precursor yarns in the combined carbon fiber precursor fiber bundle alternately repeat continuous right rotation and continuous left rotation with the central axis in the longitudinal direction of the carbon fiber precursor fiber bundle as the rotation axis. A roller, which is a thread path regulating member and a thread path regulating member for skewing, was arranged, passed through a carbon fiber precursor fiber bundle, and wound on a bobbin. The yarn width of the obtained carbon fiber precursor fiber bundle was 4.5 mm, and the degree of entanglement of the carbon fiber precursor yarn obtained by dividing the carbon fiber precursor fiber bundle was 5 by the hook drop method. The carbon fiber precursor yarn alternately repeated clockwise rotation and counterclockwise rotation, and the maximum continuous rotation speed was two rotations. When the obtained carbon fiber precursor fiber bundle was unwound from the bobbin and divided into two carbon fiber precursor yarns, 10,000 m could be divided. The number of fluffs at that time was 0/100 m.

<Evaluation of divisionability>
The carbon fiber precursor fiber bundle produced by the method of the present invention is divided at a position 5 m in the unwinding direction of the bobbin via a dividing bar arranged at 5 mm intervals, and 10,000 m is unwound at 100 m / min. It was measured whether or not the split state could be continued at that time. The evaluation was good when 10,000 m was unraveled, and poor when it was less than 10,000 m and could not be divided.

<Measurement of the number of fluff after division>
Dividing bars are arranged at 5 mm intervals at a position 5 m in the unwinding direction of the bobbin around which the carbon fiber precursor fiber bundle produced as described above is wound, and the carbon fiber precursor fiber bundle is divided by the split bar. On the other hand, if there was a filament that broke when it was unwound at 100 m / min for 1 minute, it was counted as 1 time. All the divided carbon fiber precursor yarns were measured, and the total number of fluffs (pieces / 100 m) was taken.

[Example 2]
Each of the three carbon fiber precursor yarns having 3000 filaments obtained by the method of Example 1 was subjected to air entanglement treatment, flattening treatment, and adjusted to a yarn width of 3.0 mm, and then 4 A carbon fiber precursor fiber bundle was produced and evaluated in the same manner as in Example 1 except that the yarns were layered and laminated on a grooved guide roller having a flat portion having a width of 0.0 mm. The evaluation results are shown in Table 1.

[Example 3]
3. Each of the four carbon fiber precursor yarns having 3000 filaments obtained by the method of Example 1 was subjected to air entanglement treatment and then flattened to adjust the yarn width to 3.0 mm. A carbon fiber precursor fiber bundle was produced and evaluated in the same manner as in Example 1 except that the yarns were layered and laminated on a grooved guide roller having a flat portion having a width of 0 mm. The evaluation results are shown in Table 1.

[Example 4]
A carbon fiber precursor fiber bundle was produced and evaluated in the same manner as in Example 3 except that the treatment pressure of the air entanglement treatment was increased and the degree of entanglement of the carbon fiber precursor yarn was increased. The evaluation results are shown in Table 1.

[Example 5]
A carbon fiber precursor fiber bundle was produced and evaluated in the same manner as in Example 4 except that the treatment pressure of the air entanglement treatment was further increased and the degree of entanglement of the carbon fiber precursor yarn was increased. The evaluation results are shown in Table 1.

[Example 6]
Each of the two carbon fiber precursor yarns having 12,000 filaments obtained by the method of Example 1 was subjected to an air entanglement treatment and then flattened to adjust the yarn width to 6.0 mm. A carbon fiber precursor fiber bundle was produced and evaluated in the same manner as in Example 1 except that the yarns were layered and laminated on a grooved guide roller having a flat portion having a width of 0 mm. The evaluation results are shown in Table 1.

[Example 7]
By adjusting the position of the thread path regulating member for skewing and increasing the skew angle θ of the carbon fiber precursor fiber bundle, the maximum continuous rotation speed of the carbon fiber precursor fiber bundle in the carbon fiber precursor fiber bundle can be increased. A carbon fiber precursor fiber bundle was produced and evaluated in the same manner as in Example 6 except that it was changed to increase. The evaluation results are shown in Table 1.

[Comparative Example 1]
A carbon fiber precursor fiber bundle was produced and evaluated in the same manner as in Example 1 except that the treatment pressure of the air entanglement treatment was lowered and the degree of entanglement of the carbon fiber precursor yarn was lowered. The evaluation results are shown in Table 1.

[Comparative Example 2]
2. Each of the two carbon fiber precursor yarns having 3000 filaments obtained by the method of Example 1 was subjected to air entanglement treatment and then flattened to adjust the yarn width to 3.0 mm. On a grooved guide roller having a flat portion having a width of 0 mm, the yarns were layered and combined to obtain a carbon fiber precursor fiber bundle, and then wound once on a bobbin. The obtained carbon fiber precursor fiber bundle was twisted using a twisting machine so that only clockwise rotation was 2 rotations per 1 m, and the carbon fiber precursor fiber bundle was wound again on a bobbin. The yarn width of the obtained carbon fiber precursor fiber bundle is 4.0 mm, and the degree of entanglement of the carbon fiber precursor yarn obtained by splitting the carbon fiber precursor fiber bundle while twisting is 10 by the hook drop method. , The carbon fiber precursor yarn was applied only clockwise over the entire length. When the obtained carbon fiber precursor fiber bundle was unwound from the bobbin and divided into two fibers, thread breakage occurred and the 10,000 m could not be divided. The number of fluffs could not be measured because 100 m could not be unwound and thread breakage occurred.

[Comparative Example 3]
2. Each of the two carbon fiber precursor yarns having 3000 filaments obtained by the method of Example 1 was subjected to air entanglement treatment and then flattened to adjust the yarn width to 3.0 mm. On a grooved guide roller having a flat portion having a width of 0 mm, the yarns were layered and combined, and wound on a bobbin. The thread width of the obtained carbon fiber precursor fiber bundle is 4.5 mm, the degree of entanglement of the carbon fiber precursor fiber bundle obtained by dividing the carbon fiber precursor fiber bundle by the hook drop method is 5, and the carbon fiber precursor. There was no spinal rotation. When the obtained carbon fiber precursor fiber bundle was unwound from the bobbin and divided into two, one carbon fiber precursor thread was separated and thread sagging occurred, so that 10,000 m could be divided. could not. The number of fluffs before the occurrence of thread sagging was 2 pieces / 100 m.

[Comparative Example 4]
A carbon fiber precursor fiber bundle was produced and evaluated in the same manner as in Example 2 except that the treatment pressure of the air entanglement treatment was lowered and the degree of entanglement of the carbon fiber precursor yarn was lowered. The evaluation results are shown in Table 1.

[Comparative Example 5]
2. After each of the three carbon fiber precursor yarns having 3000 filaments obtained by the method of Example 1 was subjected to an air entanglement treatment and then flattened to adjust the yarn width to 3.0 mm. The yarn was combined on a grooved guide roller having a flat portion having a width of 0 mm to obtain a carbon fiber precursor fiber bundle, and then wound on a bobbin. The yarn width of the obtained carbon fiber precursor fiber bundle was 2.8 mm, and the carbon fiber precursor yarn obtained by dividing the carbon fiber precursor fiber bundle had flat yarns folded in the longitudinal direction. The degree of entanglement of the carbon fiber precursor yarns by the hook drop method was 8, and the presence or absence of alternating rotation and the maximum continuous rotation speed could not be measured due to the entanglement of the carbon fiber precursor yarns. When the obtained carbon fiber precursor fiber bundle was unwound from the bobbin and divided into three fibers, thread breakage occurred and it was not possible to divide 10,000 m. The number of fluffs before the yarn breakage was 12/100 m.

[Comparative Example 6]
Each of the three carbon fiber precursor yarns having 3000 filaments obtained by the method of Example 1 was subjected to air entanglement treatment and then flattened to adjust the yarn width to 3.0 mm. The yarn was combined on a grooved guide roller having a flat portion having a width of 0 mm to obtain a carbon fiber precursor fiber bundle, and then wound on a bobbin. The yarn width of the obtained carbon fiber precursor fiber bundle is 7.5 mm, the degree of entanglement of the carbon fiber precursor yarn obtained by dividing the carbon fiber precursor fiber bundle by the hook drop method is 5, and the carbon fiber precursor. Due to the entanglement of the body threads, the presence or absence of alternating rotation and the maximum continuous rotation speed could not be measured. When the obtained carbon fiber precursor fiber bundle was unwound from the bobbin and divided into three fibers, 10,000 m could be divided, but the number of fluffs at that time deteriorated to 10/100 m.

[Comparative Example 7]
Each of the three carbon fiber precursor yarns having 3000 filaments obtained by the method of Example 1 was subjected to an air entanglement treatment and then flattened to adjust the yarn width to 3.0 mm, and then a V-groove. The yarn was combined on a guide roller to obtain a carbon fiber precursor fiber bundle, and then wound on a bobbin. The yarn width of the obtained carbon fiber precursor fiber bundle is 5.0 mm, the degree of entanglement of the carbon fiber precursor yarn obtained by dividing the carbon fiber precursor fiber bundle by the hook drop method is 5, and the carbon fiber precursor. Due to the entanglement of the body threads, the presence or absence of alternating rotation and the maximum continuous rotation speed could not be measured. When the obtained carbon fiber precursor fiber bundle was unwound from the bobbin and divided into three fibers, 10,000 m could be divided, but the number of fluffs at that time deteriorated to 13/100 m.

[Comparative Example 8]
A carbon fiber precursor fiber bundle was produced and evaluated in the same manner as in Example 3 except that the treatment pressure of the air entanglement treatment was lowered and the degree of entanglement of the carbon fiber precursor yarn was lowered. The evaluation results are shown in Table 1.

[Comparative Example 9]
By adjusting the position of the thread path regulating member for skewing and increasing the skew angle θ of the carbon fiber precursor fiber bundle, the maximum continuous rotation speed of the carbon fiber precursor fiber bundle in the carbon fiber precursor fiber bundle can be increased. A carbon fiber precursor fiber bundle was produced and evaluated in the same manner as in Example 4 except that it was changed to increase. The evaluation results are shown in Table 1.

[Comparative Example 10]
A carbon fiber precursor fiber bundle was produced and evaluated in the same manner as in Example 5 except that the treatment pressure of the air entanglement treatment was further increased and the degree of entanglement of the carbon fiber precursor yarn was increased. As a result of increasing the degree of entanglement, the yarn width of the carbon fiber precursor yarn became 2.5 mm. The evaluation results are shown in Table 1.

[Comparative Example 11]
A carbon fiber precursor fiber bundle was produced and evaluated in the same manner as in Example 6 except that the treatment pressure of the air entanglement treatment was lowered and the degree of entanglement of the carbon fiber precursor yarn was lowered. The evaluation results are shown in Table 1.

[Comparative Example 12]
The processing pressure of the air entanglement treatment was increased, the degree of entanglement of the carbon fiber precursor fibers was increased, and the position of the thread path regulating member for skewing was adjusted to increase the oblique angle θ of the carbon fiber precursor fiber bundle. By doing so, a carbon fiber precursor fiber bundle was produced and evaluated in the same manner as in Example 7 except that the maximum continuous rotation speed of the carbon fiber precursor fibers in the carbon fiber precursor fiber bundle was changed. .. The evaluation results are shown in Table 1.

The carbon fiber precursor fiber bundle obtained by the present invention has excellent process passability as compared with the conventional carbon fiber precursor fiber bundle, and also causes fluffing when divided into carbon fiber precursor fiber threads. It can be reduced.

1, 1', 1'': Carbon fiber precursor thread 2: Carbon fiber precursor fiber bundle 3: Central axis of carbon fiber precursor fiber bundle 4: Grooved guide roller for combined yarn 5: Thread path regulating member 6 : Oblique thread path regulating member θ: Oblique angle A: Travel direction B: Left rotation toward the travel direction C: Right rotation toward the travel direction

Claims

It is a carbon fiber precursor fiber bundle in which a plurality of flat carbon fiber precursor threads are interlaced, and the degree of entanglement required by the hook drop method of the carbon fiber precursor threads is 5 or more and 23 or less. The thread width X of the carbon fiber precursor fiber bundle is within the range of W ≦ X ≦ 2.2 W with respect to the thread width W of the carbon fiber precursor thread, and the carbon fibers are contained in the carbon fiber precursor fiber bundle. The precursor thread alternately repeats continuous right rotation of 0.5 rotation or more and 5 rotations or less and continuous left rotation of 0.5 rotation or more and 5 rotations or less with the central axis in the longitudinal direction of the carbon fiber precursor fiber bundle as the rotation axis. Carbon fiber precursor fiber bundles arranged so as to.
The carbon fiber precursor fiber bundle according to claim 1, wherein the number of filaments of the carbon fiber precursor yarn is 1000 or more and 24,000 or less.
A method for producing a carbon fiber precursor fiber bundle by combining a plurality of carbon fiber precursor threads to obtain a carbon fiber precursor fiber bundle, wherein the carbon fiber precursor threads are flat and a hook drop method. When the degree of entanglement obtained by the above is 5 or more and 23 or less and the thread width of the carbon fiber precursor threads is W, the width Y of the flat portion of the plurality of carbon fiber precursor threads is W ≦ Y ≦ 2. . On the flat part of the grooved guide roller within the range of 2 W, the carbon fiber precursor fibers are combined in layers to form a carbon fiber precursor fiber bundle, and then the carbon fiber precursor fibers are used using a plurality of thread path regulating members. By skewing the bundle, rotation is imparted to the carbon fiber precursor threads in the carbon fiber precursor fiber bundle, and the carbon fiber precursor threads rotate about the central axis in the longitudinal direction of the carbon fiber precursor fiber bundle. Manufacture of a carbon fiber precursor fiber bundle in which the thread path regulating member is arranged so as to alternately repeat continuous right rotation of 0.5 rotation or more and 5 rotations or less and continuous left rotation of 0.5 rotation or more and 5 rotations or less. Method.