JP2014005580A - Method for opening and transporting carbon fiber bundle, and method for producing carbon fiber unidirectional prepreg - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a method for opening and transporting a fiber bundle which transports a previously opened fiber bundle while maintaining sufficiently opened state without degradation such as thread breakage and decline in work efficiency at the time of start; and a method for producing a carbon fiber unidirectional prepreg using such the method.SOLUTION: In a method for opening and transporting a carbon fiber bundle which is used for a step of producing a carbon fiber unidirectional prepreg, the carbon fiber bundle is scratched against or touched with a plurality of opening members arranged such that a thread guide for the carbon fiber bundle is in a zigzag shape while the carbon fiber bundle is opened by opening members vibrating in the vertical direction against the transportation direction of the carbon fiber bundle, among the plurality of opening members. Thereafter, a tension of the fiber bundle at the time of laminating device introduction is caused to drop against a tension at the time of opening, and the fiber bundle is transported to the laminating step.

Description

  In the present invention, when a carbon fiber bundle to be supplied to a laminating apparatus in a carbon fiber unidirectional prepreg manufacturing process is pre-opened, widened and transported, it is particularly suitable for manufacturing a thin sheet having a large amount of widening. The present invention relates to a conveyance method and a method for producing a carbon fiber unidirectional prepreg to which such a method is applied.

  In recent years, a unidirectional prepreg formed by impregnating a reinforcing fiber bundle such as carbon fiber with a matrix resin such as an epoxy resin or an unsaturated polyester resin in the form of a sheet has been used because of its light weight and high strength. It is used for a wide range of applications such as sports and leisure, aircraft materials, medical materials, and industrial materials. Taking advantage of the light weight and high strength characteristics of such carbon fibers, the demand for so-called thin prepregs with low fiber basis weight is rapidly increasing, and further, there is an increasing demand for high-quality prepregs with less thickness unevenness even in thin prepregs. ing. The unidirectional prepreg is manufactured by impregnating a matrix resin between single yarns in a state where fiber bundles are arranged in a sheet form. At this time, it is desirable that the thinner the prepreg is, the pre-opening is performed in a state where the fiber bundle is sufficiently opened before the resin is impregnated. While the fiber bundle passes through the conveying part until impregnation, the fiber bundle once opened by the pre-opening contracts unevenly in the width direction due to the influence of the entanglement of the single yarn constituting the fiber bundle, etc. When trying to manufacture a thin prepreg, there are thick spots due to widening spots, the thickness of the prepreg does not become thin, thickness spots are generated, the inside of the fiber is not impregnated with the matrix resin, and cracks occur between the fiber bundles Will occur.

  Therefore, in order to produce a high-quality unidirectional prepreg without cracks that is thin and has few thickness spots and is sufficiently impregnated with the matrix resin up to the inside of the fiber bundle, the fiber bundle is used until just before impregnation with the resin. Must be held in a sufficiently uniform state in advance.

  As a method of pre-opening the carbon fiber bundle into a thin sheet shape to make a unidirectional prepreg, in particular, in order to greatly widen the fiber bundle, the carbon fiber bundle is longitudinally moved by impact or vibration with a roll or bar. In general, a method of opening a fiber while being tensioned or relaxed is used. Such a method is effective for producing a thin unidirectional prepreg because the carbon fiber bundle can be greatly widened, but usually for aligning the carbon fiber bundle and for producing a fiber opening effect. Since the fiber bundle is supplied to the opening device with some tension applied by the creel, and the fiber bundle is further tensioned by vibration in the opening device, an excessive tension is applied to the opened fiber bundle, and the opening device Since the fiber bundle shrinks in the width direction in the free zone from the time it exits to the laminator, it maintains a uniform arrangement in one direction with no gaps, especially when the widening ratio is large. Therefore, it was difficult to carry it to the laminating process.

  In the prior art, in order to prevent this, there is a technology that reduces re-shrinkage by gripping a non-vibrating roll immediately after opening by impact or vibration with a roll or bar having a rough surface such as a satin surface. In these methods, in order to obtain a gripping force sufficient to overcome the force that the opened fiber bundle tries to converge again, these methods are applied to the fiber bundle. Eventually, it was necessary to apply an excessive tension and roughen the surface roughness of the roll or bar brought into contact with the fiber bundle to some extent. However, in these methods, there is a problem in that fluffing of the fibers causes fluff due to single yarn breakage, and the single fibers are easily taken on the roll, and in some cases the fiber bundle is wound. For this reason, there is a demand for a method of preventing excessive tension from being applied by opening and conveying the laminate to a laminating apparatus while maintaining a stably widened state.

  As a method for conveying a fiber bundle that has been opened after preliminary opening in response to the above problem, Patent Document 3 discloses that after opening the fiber, the shaft is contacted and passed through a roll connected to a powder brake. Although it is disclosed that the tension is stabilized by this, the rotation speed of the brake roll is rotated at a low speed with respect to the prepreg conveyance speed. In particular, the tension was high, and the fiber bundles that were opened were shrunk while being conveyed in the free zone from the brake roll to the laminator, and there was a problem that unevenness and cracking were likely to occur in the unidirectional prepreg. .

Further, Patent Document 4 discloses a technique relating to a method for moving the opened fiber bundle at a constant width. However, when the fiber bundle is conveyed by such a curved belt, the fiber bundle is tensioned to some extent. Strong contact is made at a point on the supporting roll, but the belt and fiber bundle are parallel to each other in other places, so the belt member is not in strong contact, so that the fiber bundle is sufficiently contracted. Cannot be stopped.
Further, in the case of a fiber bundle that is repeatedly tensioned / relaxed, the tension / relaxation action of the tension propagates only by being placed on such a belt, so that it is still easily contracted.

JP 59-228036 A Japanese Patent Laid-Open No. 10-404 Japanese Patent Laid-Open No. 2004-225222 Japanese Patent Laid-Open No. 2001-162689

  In the present invention, in view of the above-described problems of the prior art, when opening a carbon fiber bundle, the carbon fiber bundle is sufficiently opened without quality deterioration such as thread breakage or work efficiency at the start. To provide a method for opening and transporting a carbon fiber bundle that can be transported to a laminating apparatus while maintaining the state while fibering, and a method for producing a carbon fiber unidirectional prepreg using such a method With the goal.

  In order to solve the above problems, the present invention has the following configuration. That is, in the opening method of the carbon fiber bundle supplied to the manufacturing process of the carbon fiber unidirectional prepreg, the carbon fiber bundle is abraded to a plurality of opening members arranged so that the yarn path of the carbon fiber bundle is zigzag-shaped. While opening, the carbon fiber bundle is opened by a free rotating roll that vibrates in the vertical direction with respect to the conveying direction of the carbon fiber bundle among the plurality of opening members, and then conveyed by being held by a plurality of driving rotating rolls. However, the carbon fiber bundle opening / conveying is characterized in that the tension of the carbon fiber bundle at the time of introduction of the laminating apparatus is reduced with respect to the opening tension defined in the specification and conveyed to the laminating process. Is the method.

  In the fiber opening / conveying method described above, the carbon at the time of introducing the laminating apparatus is obtained by rotating the driving roll speed at a high speed with respect to the prepreg conveying speed while holding the carbon fiber bundle by the driving roll described above. It is preferable to control the tension of the fiber bundle to 15 to 100 g / bundle.

  Furthermore, a carbon fiber unidirectional prepreg can be produced by impregnating a carbon fiber bundle that has been opened and transported by the above-described opening and transporting method with a resin.

  When the sheet comprising the carbon fiber bundle obtained by the fiber opening / conveying method of the present invention is used for the production of the carbon fiber unidirectional prepreg, the necessary amount of the sheet comprising the carbon fiber bundle is opened, Since the shrinkage is very small, the carbon fiber unidirectional prepreg impregnated with resin has very few gaps due to cracks, and the carbon fiber unidirectional prepreg has excellent appearance quality even if the fiber basis weight is low. Manufacture is possible.

FIG. 1 is a side view of an example of an apparatus used in a carbon fiber bundle opening / conveying method according to an embodiment of the present invention.

  The present invention relates to a method for opening a carbon fiber bundle to be used in a carbon fiber unidirectional prepreg manufacturing process, and the carbon fiber bundle is attached to a plurality of opening members arranged so that the yarn path of the carbon fiber bundle is zigzag. After opening the carbon fiber bundle with the opening member that vibrates in the vertical direction with respect to the conveying direction of the carbon fiber bundle among the plurality of opening members while rubbing or contacting, the carbon fiber bundle at the time of introducing the laminating apparatus It is characterized in that the tension is lowered with respect to the tension at the time of opening and is conveyed to the laminating process. Hereinafter, preferred embodiments of the present invention will be described.

  The carbon fiber bundle (hereinafter, simply referred to as “fiber bundle”) used in the present invention is not particularly limited in its type or shape, but the shape is a 1 in which a plurality of single yarns are aligned. The fiber bundle may be a single fiber bundle, or may be a fiber bundle in which a plurality of fiber bundles are aligned with each other to form a sheet.

  The tension at the time of opening in the present invention is the tension detected by the roll (5 in FIG. 1) on the final exit side of the opening apparatus. In the present invention, the means for controlling the tension at the time of fiber opening is not particularly limited, but the air pressure is applied to the rotating shaft of the shaft on which the bobbin formed by winding each bundle of creel fibers (not shown) is mounted. Or, it is common to apply tension to the fiber bundle by braking the shaft while controlling the sliding contact force of a friction material such as a brake pad by electromagnetic action.

  In the present invention, it is preferable that the tension at the time of opening is 150 to 400 g / bundle by means of controlling the tension. By setting the tension at the time of opening to 150 g / bundle or more, meandering due to vibration at the time of opening can be prevented, and the fiber can be stably opened. This is preferable because thread pain due to abrasion can be prevented. More preferably, it is 150 to 200 g / bundle.

  In the present invention, the prepreg conveyance speed described below refers to the carbon fiber after resin impregnation in the nip roll disposed in the laminating process, which is the subsequent process of the fiber opening process after the fiber opening process. It is the rotational speed of the roll that is pulled out while sandwiching the directional prepreg together with the resin film.

  The present invention reduces the tension when the fiber bundle laminating apparatus is introduced by a method such as increasing the rotational speed of the drive rolls (6a to 6e) with respect to the roll speed (that is, the prepreg conveying speed). The fiber bundle after opening is conveyed to a laminating apparatus.

  A plurality of fiber-opening members used in the present invention, which are arranged so that the yarn path of the carbon fiber bundle has a zigzag shape, specifically, a rod-like shape having a round contact portion with a fiber and a polygonal cross section Examples thereof include a fixed bar and a roll capable of rotating around an axis.

  As the cross-sectional shape of the preferred opening member, a rotationally symmetric structure is preferable with respect to the center of rotation so that the fiber bundles are evenly scraped or contacted, and the number of contact portions per member is widening performance, widening in the width direction. From the relationship with spots and meandering, 4 to 32 is preferable. The shape of the opening member is not particularly limited as long as it is difficult to bend in the width direction, and is a type in which it is struck by a rotary body such as a vertical reciprocating body or a ladder roll or a so-called eccentric rotating body. It may be. In addition, the roundness of the contact portion with the fiber bundle is preferably in the range of 1 to 10 mm in the radius of curvature r of the contact portion from the viewpoint of abrasion of the fiber bundle.

  In addition, as the material constituting the spread member, stainless steel, ceramics, general carbon steel, etc. can be preferably used, but other materials can be used as long as the amount of bending is small and the strength is not insufficient. be able to.

  Among the spread members, the number of members that vibrate in the vertical direction is 1 to 10, more preferably 1 to 6 from the viewpoint of spread spots and meandering. Moreover, you may arrange | position the member which vibrates not only the vibration of an up-down direction but the axial direction of a member as an opening member as the above-mentioned shape.

  In the present invention, it is preferable to control the tension of the fiber bundle at the time of introducing the laminating apparatus to 15 to 100 g / bundle by adjusting the rotation speed of the driving roll. By making the tension of the fiber bundle 15 g / bundle or more, meandering at the time of carrying the fiber bundle can be prevented and stably conveyed. By making the tension 100 g / bundle or less, the width of the widened fiber bundle can be reduced. It becomes possible to convey while preventing shrinkage. More preferably, the tension of the fiber bundle when the laminating apparatus is introduced is 15 to 50 g / bundle or less.

  The method for controlling the tension of the fiber bundle is not particularly limited, but a known tension detection roll is arranged on the fiber bundle before supplying the laminating apparatus, and the rotation speed of the drive roll is adjusted so that the tension is within the control range. A method of adjusting and controlling is preferable. In addition, in order to prevent the winding of a fiber on the surface of these rolls, what has been satin-finished is preferable.

  The number of the drive rolls is not particularly limited as long as it is a level that can reduce the tension action of the fiber bundle by the member that vibrates in the vertical direction in the fiber opening process, but from the viewpoint of complication of the device and cost, 2 20 is preferable, and 2-14 is more preferable.

  A member that vibrates in the vertical direction by rotating the drive roll at a speed higher than the prepreg conveyance speed and relaxing the tension while arranging such a drive roll from the opening to the laminating apparatus to grip the fiber bundle. It is possible to relieve the tension effect of tension and to convey the fiber bundle to the laminating apparatus while maintaining the width of the fiber bundle. Further, at this time, not only the drive roll is rotated at a high speed but also is swung in the axial direction, and the friction force between the fiber bundle and the roll tends to widen in the width direction. It is also possible to transport to the laminating apparatus while actively preventing this.

  In the present invention, by using the fiber bundle conveyed using the fiber opening / conveying method having the configuration as described above, impregnating the fiber bundle with a resin to produce a carbon fiber unidirectional prepreg, It is possible to produce a high-quality carbon fiber unidirectional prepreg having a small thickness and little cracking and having a fiber bundle sufficiently impregnated with a resin.

  Here, the resin used or the impregnation method of the resin is not particularly limited. Examples of the resin include thermosetting resins such as epoxy resins, vinyl ester resins, unsaturated polyester resins, and phenol resins, and thermoplastic resins such as polyester resins, polyethylene resins, polycarbonate resins, polyether resins, and polyamide resins. It is done. Further, the impregnation method is, for example, a method in which a fiber bundle is sandwiched between two resin sheets obtained by thinly and uniformly applying the above resin to a sheet such as paper or resin film that has been subjected to a release treatment, The method of pressurizing with a roll etc. is mentioned.

  Examples of the fiber bundle suitably used in the present invention include carbon fibers and graphite fibers, and the effect is particularly great when the tensile elastic modulus of these reinforcing fibers is 200 to 700 GPa, preferably 230 to 650 GPa. The number of single fibers constituting the fiber bundle is 1,000 to 100,000, preferably 3,000 to 24,000.

As the unidirectional prepreg is suitably produced in the present invention, the basis weight of the reinforcing fibers, 10 to 200 g / ^{m 2,} preferably the effect is large in the case of 10 to 100 g / ^{m 2.} The fiber mass content of the unidirectional prepreg is 30 to 90% by mass, preferably 60 to 90% by mass.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the scope of the present invention is not limited to the following examples. The “reduction ratio” of the fiber bundle width described below is the fiber bundle width (W ₀ ) when the fiber bundle width is on the free roll (5) of FIG. The ratio ([(W ₀ −W ₁ ) / W ₀ ] × 100 (%)) in which the fiber bundle width (W ₁ ) on the laminating apparatus introduction roll (9b) is narrowed, and represents the prepreg quality. “Wale” means a gap having a gap in the width direction of 0.5 mm or more between fibers.

(Examples 1-3)
Using the fiber bundle conveying device (6a to 6e, 7) shown in FIG. 1, the carbon fiber unidirectional prepreg width is 1000 mm, the fiber basis weight is 80 g / m ² , and the fiber mass content is 70% by mass. The carbon fiber (T700SC-12K manufactured by Toray Industries, Inc.) was spread and widened in advance to a predetermined width using free rolls (4a, 4b) that vibrate in the vertical direction while being conveyed. The tension at the opening of the creel was controlled so that the tension detected by the roll 5 was 150, 200 g / bundle. Thereafter, the drive rolls (6a to 6e) were further swung in the axial direction while controlling the speed of the drive rolls (6a to 6e) so that the tension detected by the roll 7 was 15, 50, and 100 g / bundle. However (Table 1), the fiber bundle could be conveyed while maintaining its width substantially. Further, the carbon fiber unidirectional prepreg sheet obtained at this time had almost no cracks between the fibers, and the quality was good.

(Examples 4 to 6)
In Examples 1 to 3, the tension detected by the roll 7 is 15 in the same manner as in Examples 1 to 3 except that the drive rolls (6a to 6e) of the fiber bundle conveying device are not swung in the axial direction. When the speed of the drive rolls (6a to 6e) was controlled so as to be 50, 100 g / bundle (Table 1), the fiber bundle could be conveyed while maintaining its width substantially. Further, the carbon fiber unidirectional prepreg sheet obtained at this time had almost no cracks between the fibers, and the quality was good.

(Comparative Examples 1 and 2)
As a comparative example, using the driving rolls (6a to 6e) shown in FIG. The drive roll (6a-6e) speed is controlled so that the tension detected by the rolls 5 and 7 is equal to 150, 200 g / bundle, and further, the tension is swung in the axial direction, and the tension at the time of opening is not lowered. When it was made to do (Table 1), the width | variety of the fiber bundle after fiber opening narrowed gradually, and the width | variety in the entrance side of a lamination apparatus reduced to 10 to 20% with respect to the width | variety just after fiber opening (table | surface). 1). In addition, the carbon fiber unidirectional prepreg obtained at this time had many cracks, resulting in poor quality.

(Comparative Examples 3 and 4)
In Comparative Examples 1 to 3, when the creel tension was controlled so that the tension detected by the roll 5 was 150, 200 g / bundle without using the drive rolls (6a to 6e) and the tension detection roll 7, The width of the subsequent fiber bundle was gradually reduced, and the width on the entry side of the laminating apparatus was reduced to 15 to 25% with respect to the width immediately after opening (Table 1). In addition, the carbon fiber unidirectional prepreg obtained at this time had many cracks, resulting in poor quality.

1: Fiber bundle 2: Free rolls 3a, 3b, 3c: Contact angle adjusting free rolls with vibrating rolls 4a, 4b: Vertical vibrating rolls 5: Tension detection rolls 6a, 6b, 6c, 6d (at the time of fiber opening) 6e: Drive roll 7: Tension detection roll 8a, 8b (at the time of laminating apparatus introduction) 8a, 8b: Resin film 9a, 9b: Laminating apparatus introduction roll 10a, 10b: Impregnation roll 11a, 11b: Nip roll

Claims (4)

In the method for opening a carbon fiber bundle to be used in the manufacturing process of the carbon fiber unidirectional prepreg, the carbon fiber bundle is abraded or brought into contact with a plurality of opening members arranged so that the yarn path of the carbon fiber bundle is zigzag-shaped. However, after the carbon fiber bundle is opened by the opening member that vibrates in the vertical direction with respect to the conveying direction of the carbon fiber bundle among the plurality of opening members, the tension of the carbon fiber bundle when the laminating apparatus is introduced is opened. A method for opening and transporting a carbon fiber bundle, characterized in that the carbon fiber bundle is transported to a laminating step after being lowered with respect to tension at the time. The carbon fiber bundle tension at the time of introducing the laminating apparatus is controlled to 15 to 100 g / bundle by rotating the drive roll speed at a high speed with respect to the prepreg conveying speed while gripping the carbon fiber bundle by a plurality of drive rolls. The method for opening and conveying a carbon fiber bundle according to claim 1. The method for opening and transporting a carbon fiber bundle according to claim 2, wherein the drive roll is swung in the axial direction. The manufacturing method of the carbon fiber unidirectional prepreg which impregnates the carbon fiber bundle opened and conveyed by the fiber opening and conveyance method in any one of Claims 1-3 to make a unidirectional prepreg.

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