JPH0657543A - Production of composite material having highly oriented short fiber - Google Patents

Abstract

PURPOSE:To obtain a composite material excellent in mechanical strength such as strength or modulus by flying and feeding a short fiber-like reinforcing fiber and a short fiber-like thermoplastic material in a specific state. CONSTITUTION:A sliver 2 constituted of a short-fiber like reinforced fiber and a short-fiber-like thermoplastic matrix resin is flown while exerting stretching action upon the fiber by a transporting duct 7 having an ejector. The posture of fiber is changed in this transporting duct and the fiber is landed on a perforated belt 8 from the rear end and formed from an accumulating part D having a suction device 9 through a joining part E into a sheet.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a highly oriented short fiber composite material comprising a reinforcing fiber and a short fiber thermoplastic material.

[0002]

2. Description of the Related Art A technique for highly orienting short fiber-shaped fiber aggregates is a very useful technique in industry, and research is being conducted in various fields. Particularly in the field of fiber-reinforced composite materials, which have undergone remarkable technological progress in recent years, research on this technology has been actively conducted. Fiber-reinforced composite materials obtained by mixing reinforcing fibers into various matrix resins have excellent mechanical properties such as high strength and high elastic modulus, and are therefore used in various fields. As the form of the reinforcing fibers, long fibers for use in the fields of high strength and high elastic modulus, to improve the formability of composite materials using long fibers, and for use in the fields of low strength and low elastic modulus There are two forms of short fiber. Among these, as a molding method of a composite material in which a thermoplastic resin is used as a matrix and a short fiber-like fiber base material is highly oriented to form a reinforcing material, (1) a short fiber-like reinforced fiber base material and a thermoplastic resin are used. A method of orienting short fibers by suspending a mixture of the following short fibrous matrix material in a liquid and passing this suspension through a porous wall (JP-A-57-178720), (2) ) A draft action is given to a short fiber aggregate in which a short fibrous reinforcing fiber base material and a short fibrous matrix material made of a thermoplastic material are mixed, and the fibers are orientated in a draft direction by friction between the fibers. A method of joining and integrating reinforcing fibers with each other by heating and melting a short fibrous matrix material in a fiber assembly (JP-B-56-37892).
Have been proposed.

[0003]

[Problems to be Solved by the Invention] However, (1)
According to the example of the patent, the method of (1) uses only short fibers of about 3 mm as the reinforcing fiber, and the reinforcing effect by the fiber base material is not sufficiently exhibited. Further, the method (2) has the advantage that a relatively long reinforcing fiber can be used and the mixed state of the fiber base material and the matrix resin is good, but according to the examples of the patent, the bending strength is not improved so much. Therefore, there are problems that the reinforcing fibers are not completely oriented by the draft and the reinforcing effect of the fiber base material is not sufficiently exhibited.

The object of the present invention is to solve these problems.

[0005]

Means for Solving the Problem The present invention uses short-fiber reinforcing fibers and short-fiber thermoplastic materials in a transport duct with an ejector to cause the fibers to fly while always exerting a stretching action on the fibers. Furthermore, the method of manufacturing a highly oriented short fiber composite material is characterized in that the fibers are landed from the rear end by changing the fiber posture in the transportation duct.

[0006]

EXAMPLES A short fiber highly oriented composite material manufacturing apparatus as an example of a technique for highly orienting a short fibrous fiber aggregate according to the present invention by a flying method is shown. The present invention will be described below with reference to the accompanying drawings.
FIG. 1 shows a perspective view of a short fiber highly oriented composite material manufacturing apparatus which is an example of the present invention. As shown in FIG. 1, the device of the present invention comprises a fiber supplying section A, a separating section B, a transporting section C, a stacking section D, a joining section E and a winding section F.

The fiber supply section A comprises a pair of supply rolls 3 and an apron device 4, and a sliver 2 having a predetermined weight per unit length supplied from the can 1 is supplied to the supply rolls 3.
And the apron device 4 are pretensioned at a draft ratio of about 1.3 times, for example. Here, the sliver 2 is composed of short fiber reinforcing fibers 2a and short fiber matrix resin 2b made of a thermoplastic resin. As the reinforcing fibers 2a, those usually used as reinforcing fibers for composite materials, that is, carbon fibers, glass fibers, aromatic polyamide fibers, etc. can be used.
As the matrix resin 2b made of a thermoplastic resin, one having a lower decomposition point or one having a lower melting point than the reinforcing fiber 2a is used. That is, polyamide, polyester, polycarbonate, which is usually used as a thermoplastic resin,
Almost everything such as polysulfone is used.

This reinforcing fiber 2a and matrix resin 2b
The sliver 2 in which the sliver 2 is mixed can be manufactured by using the sliver manufacturing method that has been conventionally used in the spinning process. When the reinforcing fibers or the matrix resin are received in the form of filaments, a filament drafting and cutting device (not shown) may be provided in front of the fiber supplying section and the filaments may be directly supplied without being used as a sliver. In the apparatus of the present invention, the reinforcing fiber and the matrix resin are sufficiently mixed between the transporting section C and the collecting section D which will be described later.

It is preferable that the distance (gauge) between the supply roll 3 and the separating section roll is set longer than the fiber length of the fiber in the supply sliver, and the roll 4a can be used as a hollowing roll to accommodate bias cut fibers. To The length of the reinforcing fiber is preferably 50 mm or more in order to improve the strength and elastic modulus of the composite material. There is a portion of the fiber supply unit A that requires a change in the device in comparison with a normal spinning device. That is, since the elongation of the reinforcing fiber is extremely smaller than that of the normal fiber, the damage of the fiber may occur in the supply roll or the stretch-checking device. Therefore, it is necessary to consider using a rubber clothing roll for the portion that comes into contact with the reinforcing fibers.

The separating section B has a rubber roll 6 and a grooved roll 5.
Consisting of a pair of rolls (hereinafter referred to as a fiber-spreading device) and a transport duct 7 with an ejector for sucking and separating the fibers drawn out from the pair of rolls. By drafting at a double draft ratio, one fiber or several to several tens of fibers are drawn out.

FIG. 2 shows a side view of the fiber opening device. The grooved roll 5 in this fiber-spreading device is a roll known as a so-called nip fiber-spreading roll, and a thin plate 5a having at least one arc portion protruding at the same radius on the outer periphery is coaxially displaced by a constant angle. It is configured by stacking a predetermined number of sheets. As a result, when viewed from the side view shown in FIG. 2, a plurality of thin plates 5a are overlapped with each other to form a protruding arc portion 5b and a concave portion 5c which come into contact with the rubber roll 15.
When the fiber supplied from the apron device 4 is opened using the grooved roll 5, the fiber is nipped between the protruding arc portion 5b of the thin plate 5a and the rubber roll 6, as shown in FIG. The fibers f1 within the nip width corresponding to the thickness of the thin plate 5a are reliably sent to the next step. On the other hand, the fiber f2 that has entered the recess 5c shown in FIG. 2 is dragged by the frictional force between the fibers and is sent to the next step. In order to open the fiber bundle into a fiber group having a smaller number of fibers, it is preferable to use a thin plate having a thickness of several microns to several tens of microns corresponding to the thickness of the fibers. However, it is not only industrially difficult to manufacture a thin plate having such a thickness, but also it is not practical from the viewpoint of durability,
A grooved roll made of a thin plate having a thickness of 0 micron to 1 mm may be used. Similarly to the fiber supply section A, the grooved roll 5 is also preferably covered with rubber or the like on the arc portion 5b of the thin plate 5a that comes into contact with the fibers in order to avoid damage to the reinforcing fibers.

The grooved roll 5 may have a structure other than that shown in FIGS. 2 and 3, and the point is that the fiber bundle can be sent to the next step as a fiber group having a minimum number of fibers. I wish I had it. FIG. 4 shows an example of the transport duct 7 with an ejector. Transport duct with ejector 7
While further sucking the fiber group sent out from the fiber opening device into the fiber passage 7a by the air flow entering from the air supply port 7b and ejected from the guide vane portion gap 7c outside the fiber passage 7a, Is an apparatus for transporting one fiber or a group of several fibers to several tens of fibers in the extended state to the next step.

The structure of the ejector portion is such that the compressed air that has entered from the air introduction port passes through the pressure chamber and is parallel to the axis of the transport duct.
A high-speed air stream is ejected through the air passage, and the high-speed air stream is guided in front of the high-speed air stream to the fiber passage side.
A slope 7d of 0 degrees or less is provided, and the generation of suction force at this portion sucks the ambient air from the entrance of the transport duct with an ejector, so that the fibers released from the restraint of the opening device can be It can be carried through the passage to the exit of the transport duct. While the fibers are flying inside the ejector-equipped transportation duct, the fibers are subjected to a stretching action by air, and the fibers can be conveyed to the next step in a stretched state.

As a result of experiments and observations, it has been surprisingly found that the above-mentioned ejector with a slope for high-speed airflow guide has a function of significantly improving the parallelism of fibers at the time of landing of the fiber accumulation portion. As shown in FIG. 5, this ejector is arranged at an angle α of 30 degrees or less with respect to the stacking section D, and a slope 7d for high-speed airflow guide is installed in front of it at an angle of 30 degrees or less. Therefore, a skewed vortex is generated in this part, and the tip of the fiber is caught in the skewed vortex, and the fiber posture is changed from a direction substantially equal to the axis of the transport duct up to now to a direction parallel to the transport duct outlet. Turn around,
After that, it was found that it is possible to take a rear end landing posture in which the front end is lifted up with respect to the stacking section D and the rear end is tilted. Due to the realization of the trailing edge landing, there is almost no bending of the fibers at the time of landing, and the fibers land almost straight.

As shown in FIG. 1, the stacking section D comprises a perforated belt 8 and a suction device 9. The surface of the perforated belt 8 has uniform and minute holes, and the suction device 9 is connected to a suction source (not shown), so that the air above the perforated belt is sucked inward. As described above, the fibers flying from the transport duct with the ejector in the straight stretched state land on the perforated belt in the stretched state. As shown in FIG. 6, the perforated belt and the transport duct with the ejector are arranged at an angle β corresponding to the ratio of the speed of the fibers flying from the transport duct to the feed speed of the perforated belt. Are deposited in a state in which they are oriented at a right angle to the advancing direction 12 of the perforated roll. In addition, since the reinforcing fibers and the matrix resin are thoroughly mixed while landing on the accumulation part through the transport duct with ejector, when the composite material is formed, the impregnating ability of the reinforcing fibers and the matrix resin is very good and the strength of the composite material is high. Can also be excellent.

The fiber group oriented and landed in the above state is carried to the joint E by the perforated belt, where the fibrous matrix resin is melted and becomes a composite material integrated with the reinforcing fibers. After this, the composite material is wound up by the winding roll 11 of the winding portion F.

[0017]

Example 1 Table 1 below shows a comparison between the parallelism of 51 mm fibers as a raw material and the parallelism when the fibers were deposited on the accumulation part D using the apparatus of the present invention. The definition of each characteristic value used here and its evaluation method are expressed by the following equation 1.

[0018]

[Equation 1]

[0019]

[Table 1]

[0020]

INDUSTRIAL APPLICABILITY The present invention is a technique for unidirectionally orienting short fiber-like fibers of about 100 mm, and when a composite material is produced using this, mechanical strength such as strength and elastic modulus is very excellent. You can make things. Further, it can be used in a wide range of applications in other fields, for example, it can be used for strength reinforcement in a direction perpendicular to the longitudinal direction of a nonwoven fabric.

[Brief description of drawings]

FIG. 1 is a perspective view of the device of the present invention.

FIG. 2 is a side view of the separating unit B.

FIG. 3 is a side view of the separating unit B.

FIG. 4 is a sectional view of a transport duct with an ejector.

FIG. 5 is a partial side view of the device of the present invention.

FIG. 6 is a partial plan view of the device of the present invention.

[Explanation of symbols]

 1 Cans 2 Sliver 3 Supply Roll 4 Apron Device 5 Grooved Roll 6 Rubber Roll 7 Ejector Transport Duct 8 Perforated Belt 9 Suction Device 10 Matrix Resin Melting Device 11 Winding Roll 12 Perforated Belt Travel Direction

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Claims (1)

[Claims] 1. A short duct fibrous reinforcing fiber and a short fibrous thermoplastic material are used in a transport duct with an ejector to cause the fiber to fly while constantly exerting a stretching action on the fiber, and further the fiber posture in the transport duct. A method for producing a highly oriented short fiber composite material, characterized in that the fibers are landed from the rear end by changing the above.