JP2012087190A - Method for production of prepreg having discontinuous fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for production of a prepreg having discontinuous fibers, by which a unidirectional discontinuous fiber prepreg having uniform quality can be obtained and which can easily change the formation pattern of a cutting part and has high flexibility of prepreg design.SOLUTION: A film 24 comprising a thermoplastic resin is fed and laminated on one face of a strip 22 formed by aligning continuous fibers as a layered thermoplastic resin to form a laminate. Then, the laminate is irradiated with laser beam, and the continuous fibers in the strip 22 of the laminate is cut at a plurality of places in a longitudinal direction by cutting device 26 to form the cutting parts in a direction crossing the continuous fibers. After that, the strip 22 is impregnated with the thermoplastic resin to be formed into the prepreg, or after being formed into the prepreg, the laser beam is irradiated to form the cutting parts.

Description

  The present invention relates to a method for producing a prepreg (one-way discontinuous fiber prepreg) having discontinuous fibers in which a number of short fibers are oriented along the longitudinal direction.

  A unidirectional prepreg in which a fiber material oriented in one direction is impregnated with a thermoplastic resin or a thermosetting resin is known as a molding material used when obtaining a fiber-reinforced resin molded product. In such a unidirectional prepreg, long fibers are often used as a fiber material. On the other hand, a prepreg containing short fibers oriented in one direction as a fiber material has been studied. A prepreg containing short fibers oriented in one direction has the same physical properties as a prepreg containing long fibers oriented in one direction, and exhibits excellent curved surface shapeability during three-dimensional molding by pseudo extension. Expected.

  As a method for producing a prepreg containing short fibers oriented in one direction, that is, a unidirectional discontinuous fiber prepreg, for example, Patent Document 1 arranges a plurality of blades with respect to a prepreg containing long fibers oriented in one direction. A method is described in which a punched die is intermittently pressed and entered. According to such a method, it is possible to obtain a unidirectional discontinuous fiber prepreg in which a cutting line is formed by entering each blade, and each filament is appropriately cut by the cutting line to form a short fiber. Patent Document 2 describes a method of cutting a reinforcing fiber bundle covered with a thermoplastic resin with a rotary cutter. Patent Document 3 also describes a method of making a cut in a prepreg with a blade.

  Moreover, as a technique for cutting carbon fibers, for example, as described in Patent Document 4, a so-called check-out technique for drawing and cutting a fiber material is known.

JP 2009-220480 A JP 09-254227 A Japanese Unexamined Patent Publication No. 63-247010 JP-A 63-165541

  However, when carbon fiber or aramid fiber, for example, is used as the fiber material, these fibers have a higher tensile strength and higher elasticity than general organic fibers. In the method of cutting using, the cutting edge tends to deteriorate due to wear. Therefore, in the method using such a blade, stable cutting cannot be performed for a long time, and there is a tendency that a unidirectional discontinuous fiber prepreg having a certain quality cannot be obtained. Further, in the method using a cutting die or a rotary cutter, it is necessary to change the arrangement pattern of the cutting die or the blade of the rotary cutter when changing the cutting line formation pattern. Therefore, there is a problem that it is not easy to change the formation pattern of the cutting line, and the degree of freedom in prepreg design is low.

  On the other hand, when the fiber bundle is cut by the check technique described in Patent Document 4, the fiber bundle is scattered after the cutting, and the fiber orientation cannot be maintained. It is substantially difficult to manufacture a unidirectional discontinuous fiber prepreg using such a bundle of fibers in a separated state.

  The present invention was made in view of the above circumstances, and the object of the present invention is to obtain a unidirectional discontinuous fiber prepreg of a certain quality, and can easily change the formation pattern of the cutting line (cutting part), The object is to provide a method for producing a unidirectional discontinuous prepreg having a high degree of freedom in prepreg design.

The method for producing a prepreg having discontinuous fibers according to the present invention includes a laminate forming step of forming a laminate in which a strip formed by arranging continuous fibers and a thermoplastic resin layer are laminated, and irradiation with laser light. A continuous fiber in the strip is cut at a plurality of locations in the longitudinal direction to form a cut portion in a direction intersecting the continuous fiber, and the strip is impregnated with the thermoplastic resin layer to obtain a prepreg. Impregnation step.
The cutting step can be performed after the impregnation step.
The prepreg having discontinuous fibers of the present invention is manufactured by the above manufacturing method.

  According to the present invention, a unidirectional discontinuous prepreg having a certain quality can be obtained, the formation pattern of cutting lines (cutting portions) can be easily changed, and the degree of freedom of prepreg design is high. The manufacturing method of can be provided.

It is a top view which shows an example of the prepreg which has a discontinuous fiber manufactured with the manufacturing method of this invention. It is a schematic block diagram which shows an example of the manufacturing apparatus which manufactures the prepreg which has the discontinuous fiber of FIG. It is a schematic block diagram which shows another example of the manufacturing apparatus which manufactures the prepreg which has the discontinuous fiber of FIG.

Hereinafter, the manufacturing method of the prepreg which has the discontinuous fiber of this invention (henceforth a unidirectional discontinuous fiber prepreg) is demonstrated in detail.
In the present invention, the prepreg having discontinuous fibers refers to a unidirectional prepreg obtained by impregnating a thermoplastic resin into a strip in which a number of short fibers are oriented along the longitudinal direction (one direction). Say that. The short fiber means a fiber having a length of 15 mm or more and less than 200 mm, and the long fiber means a fiber having a length of 200 mm or more.

[One-way discontinuous fiber prepreg]
FIG. 1 is a plan view showing an example of a unidirectional discontinuous fiber prepreg manufactured by the manufacturing method of the present invention.
The unidirectional discontinuous fiber prepreg 10 includes a thermoplastic resin as a matrix resin, and includes, as a fiber material, carbon fiber filaments of a plurality of short fibers oriented in one direction along the longitudinal direction (arrow A direction). This is a W-band prepreg. As will be described in detail later, the fiber material included in the unidirectional discontinuous prepreg in FIG. 1 is manufactured from a single long fiber bundle (a strip formed by aligning continuous fibers) having an opened width W. It is. One long fiber bundle is usually composed of about 3,000 to 180,000 filaments. Moreover, the thickness of this one-way discontinuous fiber prepreg 10 is 0.04-0.25 mm.

The unidirectional discontinuous fiber prepreg 10 has a plurality of longitudinal positions P _n (where n = 1, 2, 3...), That is, P ₁ , P ₂ , P ₃ , P ₄ , P in this example. _In each of 5 points, a plurality of cutting lines (cuts) 11 partially formed in a direction crossing the carbon fiber filament (direction crossing the fiber direction) are provided as cutting parts.

Specifically, each cutting line 11 has a length along the width direction of the one-way discontinuous fiber prepreg 10 as L, an interval along the width direction of the one-way discontinuous fiber prepreg 10 as Q ₁ , and the one-way discontinuous fiber. interval along the longitudinal direction of the prepreg 10 are arranged in Q _2, in each of positions in the longitudinal direction along the width direction of the unidirectional discontinuous fiber prepreg 10 are intermittently formed. Moreover, each cutting line 11 is formed in the depth direction which penetrates a fiber material in the thickness direction of the unidirectional discontinuous fiber prepreg 10, ie, cuts all the fiber materials of the thickness direction.
In the fiber material included in the unidirectional discontinuous fiber prepreg 10 in FIG. 1, the carbon fiber filaments that were originally long fibers (continuous fibers) are divided in the longitudinal direction by the cutting lines 11 formed in this way. , A short fiber having a length R. Therefore, this unidirectional discontinuous fiber prepreg 10 exhibits excellent curved surface formability while having the same physical properties and handleability as a prepreg containing long fibers oriented in one direction, and is particularly a three-dimensional molded product. It is suitable for molding.

Further, in this example, the cutting lines 11 are arranged in a pattern in which the arrangement positions in the width direction of the cutting lines 11 do not coincide with each other in places adjacent to each other in the longitudinal direction, that is, _Pn and _{Pn + 1.} ing.

[Method for producing unidirectional discontinuous fiber prepreg]
Next, a method for continuously producing the unidirectional discontinuous fiber prepreg 10 in FIG. 1 will be described in detail with reference to the first and second embodiments.
FIG. 2 is a diagram illustrating the manufacturing apparatus 20 according to the first embodiment. The manufacturing apparatus 20 unwinds a continuous fiber bundle and unwinds the unrolled fiber bundle, For example, it is heated on the lower surface side of the opening device 23 that forms a flat strip having a thickness of about 0.04 to 0.25 mm and the strip-shaped fiber bundle that has been spread, that is, the continuous strip 22. A thermoplastic / resin film 24 is supplied and bonded to form a laminate including a strip 22 and a thermoplastic resin layer. The supply / bonding device 25 of this example includes a supply roll 25 a that unwinds the film 24, and a pair of nip rolls 25 b that heat and pressurize the unwound film 24 and the strip 22.

  In addition, the manufacturing apparatus 20 irradiates a laser beam on the upper surface of the band-shaped object 22 that constitutes the laminated body, on which the film 24 is not bonded, and cuts a desired portion of the band-shaped object 22. A cutting device 26 for forming the cutting line 11 is provided. The cutting device 26 of this example can freely scan a laser beam on the upper surface side of the band 22 to cut an arbitrary position of the band 22.

Further, in the manufacturing apparatus 20, after the cutting device 26 is impregnated with the film 24 of the thermoplastic resin by heating and pressurizing the strip-like material 22 after the cutting, the manufacturing apparatus 20 is cooled to obtain the unidirectional discontinuous fiber prepreg 10. A double belt type continuous processing device 27 and a winding device 33 for winding the prepreg 10 are provided.
The continuous processing device 27 includes a pair of upper and lower driven drums 28a and 28b and a pair of upper and lower driven drums 29a and 29b, and is made of stainless steel spanned between the upper driven drum 28a and the upper driving drum 29a. An endless belt 30a and a stainless steel endless belt 30b stretched over a lower driven drum 28b and a lower drive drum 29b are provided. Inside the region where the upper and lower endless belts 30a, 30b that run are opposed to each other, a heating unit including a pair of heaters 31a, 31a and a plurality of pairs of heating / pressurizing rolls 31b, 31c are provided as the heating / pressurizing device 31. A plurality of pairs of cooling rolls 32 a and 32 b are arranged as the cooling device 32. Further, in this example, the outer surfaces of the endless belts 30a and 30b are subjected to release processing using a fluorine-based resin.

When the unidirectional discontinuous fiber prepreg 10 in FIG. 1 is manufactured by the manufacturing apparatus 20, first, a continuous fiber bundle is continuously unwound by the unwinding apparatus 21, and this fiber bundle is The strip 22 is formed by rubbing or swinging with a plurality of bars to provide continuous fibers.
Next, a film (layered thermoplastic resin) 24 of a thermoplastic resin is supplied from the supply roll 25a of the supply / bonding device 25 to the lower surface side of the strip 22 thus opened, and the film 24 and the strip are supplied. 22 is sandwiched between nip rolls 25b, and these are bonded together to form a laminate in which a thermoplastic resin layer is provided on the lower surface side of the strip 22 (laminate formation step). At this time, the temperature and pressure of the nip roll 25b may be adjusted to form a so-called semi-preg state in which the film 24 is semi-impregnated into the strip 22.
Next, the laminated body of the band 22 and the film 24 is sent to the cutting device 26 while the band 22 is supported from below by the bonded film 24.

Next, the cutting device 26 irradiates the upper surface of the band 22 with laser light, scans a predetermined position of the band 22 to cut continuous fibers, and forms a plurality of cutting lines 11 in a pattern as shown in FIG. Form (cutting step).
In this example, since the strip 22 that is the object to be cut is continuously sent to the cutting device 26 at a predetermined supply speed, the cutting device 26 has a direction and a speed in consideration of the supply speed of the strip 22. The laser beam is scanned to form a plurality of cutting lines 11 continuously.

Next, a laminated body of the band-like material bundle 22 having a cutting line and the film 24 is supplied between the endless belts 30 a and 30 b of the continuous processing device 27. And then cooled by the cooling device 32.
Thereby, the unidirectional discontinuous fiber prepreg 10 obtained by impregnating the strip 22 with the cutting line with the thermoplastic resin is obtained, and the obtained unidirectional discontinuous fiber prepreg 10 is wound by the winding device 33.
A plurality of unidirectional discontinuous fiber prepregs 10 are stacked and used for molding in accordance with the shape and strength of the molded product to be produced.

  The thermoplastic resin constituting the film 24 includes polyamide, polyacetal, polyacrylate, polysulfone, ABS, polyester, acrylic resin, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene, polypropylene, polyphenylene sulfide (PPS). ), Polyether ether ketone (PEEK), liquid crystal polymer, vinyl chloride resin, polytetrafluoroethylene and other fluorine-based resins, silicone resin, and the like. Moreover, the thickness is suitably determined so that the resin content of the unidirectional discontinuous fiber prepreg is 25 to 45% by mass. The resin content is a mass ratio of the thermoplastic resin when the total mass of the thermoplastic resin and the fiber material constituting the unidirectional discontinuous fiber prepreg is 100% by mass.

As the type of laser light irradiated in the cutting process, for example, a gas laser such as a carbon dioxide laser or an excimer laser, a solid state laser such as a YAG laser or a YVO ₄ laser, and a fiber laser can be used. A solid laser and a fiber laser such as a YAG laser and a YVO ₄ laser are preferable in that they can be cut well.
As the cutting device 26 used in the cutting process, model MD-F3000 or model MD-V9900 manufactured by Keyence Corporation, model LP-Z250 manufactured by SUNX, LP-G050, LP-431U, model manufactured by Advanced Optowaves Corp. AWAVE-355-15-100K etc. are mentioned.
In addition, it is preferable to set the laser output, the oscillation mode, the scanning speed, the pulse width, the pulse frequency, and the like according to the material, the thickness, the supplied speed, and the degree of cutting in the thickness direction.

In such a manufacturing method, as described above, the cutting process is performed by laser light irradiation.
Therefore, the problem of deterioration due to abrasion of the blade edge does not occur, and stable unidirectional discontinuous fiber prepreg of a certain quality can be obtained by performing stable cutting for a long time. Further, since the formation pattern of the cutting line 11 can be easily changed simply by changing the laser scanning pattern, the degree of freedom in designing the prepreg is high.

In the first embodiment described above, the film 24 is bonded only to the lower surface side of the band-shaped object 22, but the thermoplastic resin is also formed on the upper surface side of the band-shaped object 22 between the cutting step and the impregnation step. A film may be bonded together.
Moreover, in the above example, the film 22 of thermoplastic resin is supplied from the supply / bonding device 25 arranged on the lower surface side of the belt 22 and is sandwiched between the nip rolls 25b, whereby the belt 22 and the thermoplastic resin. A laminate including the layers is formed, and then a laser beam is irradiated on the upper surface of the laminate to form a cut portion. However, by supplying a thermoplastic resin film from a supply / bonding device disposed on the upper surface side of the belt-like material and sandwiching it with a nip roll, a laminate including the belt-like material and the thermoplastic resin layer is formed, The cutting part may be formed by feeding the belt-like object to the cutting device while supporting the belt-like object from above and irradiating the belt-like object on the lower surface of the laminated body with laser light from below. As described above, in the laminated body forming step, a thermoplastic resin film is laminated on one of the upper and lower surfaces of the belt-like material, and in the subsequent cutting step, the other surface is preferably irradiated with laser light.
Further, in the laminated body forming step, a laminated body in which strips are laminated on both surfaces of the thermoplastic resin film is formed, and in the subsequent cutting step, the laminated body is irradiated with laser light to form a cutting line. be able to. In this case, the laser beam irradiation may be performed on at least one surface of the laminate, and any of the strips disposed on both surfaces can be cut even if the irradiation is performed from only one surface side. .

Next, with reference to FIG. 3, 2nd Embodiment which manufactures the unidirectional discontinuous fiber prepreg 10 of FIG. 1 continuously is described in detail.
The manufacturing apparatus 20 in FIG. 2 includes a cutting device 26 on the upstream side of the continuous processing device 27, and performs the cutting step before the impregnation step. That is, the cutting step is performed on the strip 22 before prepregization. 3 is provided with a cutting device 26 on the rear side of the continuous processing device 27, and performs the cutting step after the impregnation step. That is, the manufacturing apparatus 40 in FIG. A cutting process is performed on the cut strip 22.

When the unidirectional discontinuous fiber prepreg 10 of FIG. 1 is manufactured by the manufacturing apparatus 40 of FIG. 3, first, a continuous fiber bundle is continuously unwound by the unwinding apparatus 21, and the fiber bundle is opened. The strips 22 are opened by rubbing or swinging with a plurality of bars.
Next, a thermoplastic resin film 24 is supplied and laminated as a layered thermoplastic resin from the supply / bonding device 25 to the lower surface side of the opened band-shaped object 22, and the band-shaped object 22 and the thermoplastic resin layer are provided. A laminated body is formed (laminated body forming step).
Next, the thermoplastic resin layer is impregnated by the continuous processing device 27 as in the first embodiment and cooled to obtain a prepreg (impregnation step).

Then, the cutting device 26 irradiates laser light from the upper surface side of the prepreg, scans and cuts a predetermined position of the strip 22, and forms a plurality of cutting lines 11 as shown in FIG. 1 (cutting step). Thus, the unidirectional discontinuous fiber prepreg 10 is obtained. Thereafter, the unidirectional discontinuous fiber prepreg 10 is wound up by the winding device 33 (winding step).
Also in this example, since the prepreg which is an object to be cut is continuously sent to the cutting device 26 at a predetermined supply speed, the cutting device 26 scans the laser beam at a direction and speed considering the supply speed of the prepreg. Then, a plurality of cutting lines 11 are continuously formed.

In addition, in 2nd Embodiment demonstrated above, in the laminated body formation process, although the film 24 is bonded only to the lower surface side of the strip | belt-shaped object 22, you may bond to both an upper surface side and a lower surface side. Further, in the cutting step, the prepreg is irradiated with laser light from the upper surface side, but may be irradiated from the lower surface side or from both surfaces. When irradiating a laser beam from the lower surface side to cut the prepreg, a cutting device is disposed on the lower surface side of the prepreg to irradiate the laser beam. In addition, when irradiating laser light from both sides, a cutting device is placed above and below the prepreg, scanning a predetermined position of the prepreg, controlling the output in the thickness direction of the prepreg, and discontinuous Cut to a prepreg. In this case, by irradiating laser light to one place from both sides, a cut portion penetrating in the thickness direction may be formed, and for one place only from one of the faces. You may form the cutting part penetrated to a thickness direction by irradiating a laser beam. Also, when irradiating the laser beam from both sides, the laser beam from one side and the laser beam from the other side are scanned at different locations, and each laser beam forms a cut portion that does not penetrate in the thickness direction. Also good. That is, as long as each filament included in the unidirectional discontinuous fiber prepreg 10 is a short fiber by the cutting process, each cut portion may not penetrate.
Further, in the laminated body forming step, even when a laminated body in which strips are laminated on both surfaces of the thermoplastic resin layer is formed, laser light may be irradiated from the upper surface side or the lower surface side, or irradiation may be performed from both surface sides. May be.

  Moreover, in the laminated body formation process of 1st and 2nd embodiment, the thermoplastic resin layer is formed by using the film 24 as a material of the thermoplastic resin which is matrix resin, and bonding this to the strip | belt-shaped object 22. However, a thermoplastic resin layer may be formed by, for example, a method in which a thermoplastic resin powder (powder) is brought into contact with the strip 22 and heated or cooled. It is only necessary to form a laminate including

[Others]
In the above description, carbon fibers are exemplified as the fiber material, but fibers other than carbon fibers, such as aramid fibers, may be used. However, according to the above-described cutting step, even a carbon fiber that is more difficult to cut without disturbing the orientation can be cut well.

Moreover, in FIG. 1, as the unidirectional discontinuous fiber prepreg 10, one in which a plurality of cutting lines 11 are intermittently formed as cutting portions at each of a plurality of longitudinal positions _Pn is illustrated. However, as long as each filament included in the unidirectional discontinuous fiber prepreg 10 is a short fiber by the cutting process, the number of cutting lines in each of the locations _Pn may be one.
Moreover, in this example, as the one-way discontinuous fiber prepreg 10, the one in which the cutting lines 11 are formed in a pattern in which the arrangement positions in the width direction of the cutting lines 11 are staggered in places adjacent to each other in the longitudinal direction. However, as long as each filament included in the unidirectional discontinuous fiber prepreg 10 is a short fiber by the cutting process, the formation pattern of the cutting line 11 is not particularly limited. For example, a pattern having a certain regularity as in the example of FIG. 1 or a random pattern having no regularity may be used. The length of each cut line 11, the number of cutting lines 11, there is no limitation to such interval _Q 1, _{Q 2.}
In the illustrated example, each cutting line 11 is formed in the thickness direction of the unidirectional discontinuous fiber prepreg 10 so as to penetrate the fiber material. However, as described above, the unidirectional discontinuous fiber prepreg 10 is formed. As long as each filament contained in is made into a short fiber by the cutting process, it is not necessary that all the cutting lines penetrate in this way.

  Furthermore, in this example, the case where the direction of each cutting line 11 coincides with the width direction of the unidirectional discontinuous fiber prepreg 10 is illustrated. However, the direction of each cutting line 11 may be a direction that intersects the fiber direction. However, from the viewpoint of the cutting width depending on the spot diameter irradiated with laser light, the direction of each cutting line 11 is preferably within a range where the angle with respect to the fiber direction is 2 to 178 °. The range of 30 to 150 ° is more preferable. In addition, the direction of each cutting line does not need to correspond.

In this example, the fiber material included in the unidirectional discontinuous fiber prepreg 10 is formed from one long fiber bundle (fiber material), but a plurality of long fiber bundles are arranged in the width direction. It may be formed from a formed fiber material. In that case, it is only necessary to unwind a plurality of long fiber bundles arranged in the width direction from the unwinding device 21. According to such a method, a wide unidirectional discontinuous fiber prepreg can be obtained.
As described above, the formation pattern, number, interval, direction of the cutting line 11, the number of long fiber bundles supplied to the cutting process, etc. are the properties required for the use of the unidirectional discontinuous fiber prepreg and the molded product. It can design suitably according to etc. and there is no restriction | limiting in particular.

10 Unidirectional discontinuous fiber prepreg (prepreg having discontinuous fibers)
11 Cutting Line 22 Band 24 Film of Thermoplastic Resin 26 Cutting Device 27 Continuous Processing Device

Claims (3)

A laminated body forming step of forming a laminated body in which a strip formed by arranging continuous fibers and a thermoplastic resin layer are laminated;
A cutting step of cutting continuous fibers in the strip at a plurality of locations in the longitudinal direction by irradiation with laser light, and forming cut portions in a direction intersecting with the continuous fibers;
An impregnation step of impregnating the thermoplastic resin layer into the strip to obtain a prepreg;
A method for producing a prepreg having discontinuous fibers.   The manufacturing method of the prepreg which has a discontinuous fiber of Claim 1 which performs a cutting process after an impregnation process.   A prepreg having discontinuous fibers produced by the production method according to claim 1 or 2.

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