Apparatus and method for manufacturing fiber-reinforced thermoplastic resins

Abstract

To provide a manufacturing method and a manufacturing device for fiber-reinforced thermoplastic resin capable of continuously and reliably obtaining fiber-reinforced thermoplastic resin with desired mechanical properties.SOLUTION: A plurality of continuously fed fibers F are cut at a predetermined length by a laser that is scanned in a direction that intersects a fiber elongation direction in an upper space region of a housing part 50. The cut fibers F are kneaded with thermoplastic resin M in a molten state before being delivered.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an apparatus and a method for manufacturing a fiber reinforced thermoplastic resin, and more particularly to an apparatus and a method for manufacturing a fiber reinforced thermoplastic resin by continuously supplying fibers of a predetermined length to a molten thermoplastic resin and kneading the same.

Background Art

[0002] As such an apparatus and a method for manufacturing a fiber reinforced thermoplastic resin, for example, there is one described in Patent Document 1 below. The first material described in this Patent Document 1 is called a fiber continuous input type fiber reinforced thermoplastic resin, and is generally attracting attention as it can continuously manufacture a fiber reinforced thermoplastic resin, which has a complicated manufacturing process and takes a long time, in a short time. The apparatus and method for manufacturing this first material supply a molten thermoplastic resin to the upstream end of the content conveyance direction of a kneading (kneading) and feeding device provided with, for example, a two-axis screw blade.

[0003] In this kneading and feeding device, a plurality of fibers drawn from a plurality of bobbins, for example, carbon fibers, are continuously supplied to the same side end. The fibers continuously supplied to this kneading and feeding device are cut by the screw blade while being drawn in by the thrust of the screw blade in the device, and then kneaded with the molten thermoplastic resin by the screw blade. The fiber reinforced thermoplastic resin kneaded with relatively long fibers is, for example, sent out from the downstream end of the content conveyance direction of the kneading and feeding device, maintained in a heat-insulated state, that is, a molten state, and charged into the mold of a press device, and high-speed press molding is performed to manufacture a resin molded product.

[0004] Furthermore, Patent Document 1 discloses that, in order to improve the overall physical properties of the fiber-reinforced thermoplastic resin, a fiber-reinforced thermoplastic resin (second material), manufactured separately from the first material, is mixed with a fiber-reinforced thermoplastic resin (first material) that is continuously fed into the fiber-reinforced thermoplastic resin. This second material is obtained by cutting fibers that have been impregnated with thermoplastic resin. In addition, Patent Document 2 discloses a thermoplastic resin composition in which carbon fiber bundles cut to a predetermined length are blended into a thermoplastic resin at a blending amount of 5 to 40% by mass. In this prior art document, a rotary cutter is used to cut the carbon fiber bundles. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2019-147374 [Patent Document 2] Japanese Patent Publication No. 2004-11030 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, in the manufacturing apparatus and method for the fiber-reinforced thermoplastic resin with continuous fiber feeding described in Patent Document 1, i.e., the first material described above, the continuously supplied fibers (before cutting) are simply cut by screw blades, making it difficult to make the fiber length after cutting uniform or to control the length. Therefore, it is difficult to specify or stabilize the mechanical properties such as strength (durability) and rigidity of the fiber-reinforced thermoplastic resin as a material.

[0007] Furthermore, variations occur in the timing of when the continuous fibers are cut by the screw blades after they are supplied, resulting in an uneven mixing state between the thermoplastic resin and the fibers. If the mixing state between the thermoplastic resin and the fibers is uneven, the dispersibility of the fibers within the resin changes, making it difficult to determine the mechanical properties of the fiber-reinforced thermoplastic resin. Note that "dispersion" means being scattered or scattered, so "dispersibility" is used to describe the degree of scattering.

[0008] In other words, with conventional fiber-reinforced thermoplastic resin manufacturing apparatuses and methods that use continuous fiber feeding, it is difficult to obtain fiber-reinforced thermoplastic resins with desired mechanical properties.

[0009] Furthermore, the second material disclosed in Patent Document 1 is a fiber-reinforced thermoplastic resin manufactured separately from the first material, and is added to the first material, a fiber-injection type fiber-reinforced thermoplastic resin, which is manufactured earlier. Since this second material is made from fibers impregnated with thermoplastic resin and then cut, the cutting length is considered adjustable, but it requires a separate manufacturing process from the first material, hindering the continuity of the overall manufacturing process. In addition, there remain challenges such as the inability to determine the mechanical properties and obtain stability of the manufactured fiber-injection type fiber-reinforced thermoplastic resin.

[0010] Furthermore, when the thermoplastic resin composition described in Patent Document 2, i.e., the fiber-reinforced thermoplastic resin, is applied to a fiber-reinforced thermoplastic resin that uses continuous fiber feeding, there is a risk that the carbon fiber bundles may become frayed due to deterioration of the blade edge when cutting with a rotary cutter, or that the amount of fibers cut may be insufficient compared to the amount of fiber-reinforced thermoplastic resin that can be manufactured.

[0011] The present invention has been made in view of the above problems, and its object is to provide a manufacturing apparatus and method for fiber-reinforced thermoplastic resins that can continuously and reliably obtain fiber-reinforced thermoplastic resins with desired mechanical properties. [Means for solving the problem]

[0012] To achieve the above objective, a fiber-reinforced thermoplastic resin manufacturing apparatus according to one aspect of the present invention is a fiber-reinforced thermoplastic resin manufacturing apparatus that supplies fibers of a predetermined length to a molten thermoplastic resin contained in a kneading and dispensing device, and kneads the fibers to produce a fiber-reinforced thermoplastic resin in which the fibers have been kneaded, The apparatus comprises: a fiber supply unit that continuously supplies a plurality of fibers to the upper region of a storage unit of a predetermined volume; a fiber cutting unit that cuts the continuously supplied plurality of fibers to a certain length by a laser scanned in a direction intersecting the fiber elongation direction and drops them downward into the storage unit; a fiber dispersion unit provided at a lower position of the fiber cutting unit that disperses the fibers to be cut within the storage unit by physical stirring or airflow; a fiber introduction mechanism provided at a lower position of the fiber dispersion unit that forcibly introduces the dispersed fibers to be cut into the molten thermoplastic resin while increasing the bulk density; and a kneading and discharging unit that kneads the fibers to be cut introduced by the fiber introduction mechanism and the molten thermoplastic resin and discharges the mixture, wherein the fiber introduction mechanism is a screw-type conveying mechanism having screw blades that rotate around an axis, and is characterized in that the screw blades capture the fibers to be cut to increase their bulk density and forcibly introduce the fibers to be cut by the thrust of the screw blades. Furthermore, in order to achieve the above objective, a fiber-reinforced thermoplastic resin manufacturing apparatus according to one aspect of the present invention is a fiber-reinforced thermoplastic resin manufacturing apparatus that supplies fibers of a predetermined length to a molten thermoplastic resin contained in a kneading and dispensing device, and kneads the fibers to produce a fiber-reinforced thermoplastic resin in which the fibers have been kneaded, The apparatus comprises: a fiber supply unit that continuously supplies a plurality of fibers to the upper region of a storage unit of a predetermined volume; a fiber cutting unit that cuts the plurality of fibers that are continuously supplied to a plurality of lengths by a laser scanned in a direction intersecting the fiber elongation direction and drops them downward into the storage unit; a fiber dispersion unit provided at a lower position of the fiber cutting unit that disperses the fibers to be cut within the storage unit by physical stirring; and a kneading and dispensing unit that kneads the dispersed and dropped fibers to be cut and the molten thermoplastic resin and discharges the mixture, wherein the fiber dispersion unit includes a propeller positioned within the area where the fibers to be cut fall, and the fibers to be cut are stirred by the rotation of the propeller. Furthermore, in order to achieve the above objective, a fiber-reinforced thermoplastic resin manufacturing apparatus according to one aspect of the present invention is a fiber-reinforced thermoplastic resin manufacturing apparatus that supplies fibers of a predetermined length to a molten thermoplastic resin contained in a kneading and dispensing device, and kneads the fibers to produce a fiber-reinforced thermoplastic resin in which the fibers have been kneaded, A fiber supply unit that continuously supplies multiple fibers to the upper region of a storage unit of a predetermined volume, a fiber bundling unit that bundles the continuously supplied multiple fibers using a bundling mechanism, and the bundled bundle of fibers By a laser that scans in a direction intersecting the fiber elongation direction up to the middle of the aforementioned bundle of fibers It comprises a fiber cutting section that cuts the fibers to a certain length and drops them downward into the storage section, and a kneading and dispensing section that kneads the dropped cut fibers and the molten thermoplastic resin and then dispenses the mixture. Ta It is characterized by the following:

[0013] Furthermore, another configuration of the above-mentioned fiber-reinforced thermoplastic resin manufacturing apparatus is characterized in that the length of the cut fibers can be adjusted by controlling at least one of the fiber supply speed by the fiber supply unit and the fiber cutting timing by the fiber cutting unit.

[0014] A further configuration of the above-mentioned fiber-reinforced thermoplastic resin manufacturing apparatus is characterized in that the length of the fibers to be cut is 3 mm or more and less than 100 mm.

[0015] A further configuration of the above-described fiber-reinforced thermoplastic resin manufacturing apparatus is characterized by comprising a fiber bundling section preceding the fiber cutting section, which bundles the continuously supplied plurality of fibers using a bundling mechanism.

[0016] A further configuration of the above-described fiber-reinforced thermoplastic resin manufacturing apparatus is characterized in that the fiber bundling section comprises, as the bundling mechanism, at least one of a fiber drawing mechanism that inserts and bundles the plurality of fibers into an opening of a predetermined size, and a cross-roller mechanism that inserts and bundles the plurality of fibers into a gap formed between a plurality of rollers whose axes intersect.

[0017] A further configuration of the above-described fiber-reinforced thermoplastic resin manufacturing apparatus is characterized in that a fiber dispersion section is provided at a lower position of the fiber cutting section for dispersing the fibers to be cut within the containment section by physical stirring or airflow.

[0018] A further configuration of the above-described fiber-reinforced thermoplastic resin manufacturing apparatus is characterized by the inclusion of a fiber introduction mechanism at a lower position of the fiber dispersion section, which forcibly introduces the dispersed fibers to be cut into the molten thermoplastic resin while increasing their bulk density.

[0019] Furthermore, in order to achieve the above objective, a method for producing a fiber-reinforced thermoplastic resin according to one aspect of the present invention is a method for producing a fiber-reinforced thermoplastic resin in which fibers of a predetermined length are supplied to a thermoplastic resin in a molten state contained in a kneading and dispensing device, and kneaded, The device comprises: a fiber supply step of simultaneously and continuously supplying a plurality of fibers to the upper region of a storage section of a predetermined volume; a fiber consolidation step of consolidating the continuously supplied plurality of fibers by a consolidation mechanism; a fiber cutting step of cutting the consolidated plurality of fibers to a certain length by a laser scanned in a direction intersecting the fiber elongation direction in the upper space region of the storage section and dropping them downward into the storage section; a fiber dispersion step of dispersing the cut and dropped fibers within the storage section by physical stirring or airflow; a fiber feeding step of forcibly introducing the dispersed cut fibers into the molten thermoplastic resin while increasing its bulk density; and a kneading and discharging step of kneading the molten thermoplastic resin into which the cut fibers have been fed and discharging the kneaded material. The fiber feeding step is performed by a screw-type conveying mechanism having screw blades that rotate around an axis, and the screw blades capture the cut fibers to increase their bulk density and forcibly introduce the cut fibers by the thrust of the screw blades. Furthermore, in order to achieve the above objective, a method for producing a fiber-reinforced thermoplastic resin according to one aspect of the present invention is a method for producing a fiber-reinforced thermoplastic resin in which fibers of a predetermined length are supplied to a thermoplastic resin in a molten state contained in a kneading and dispensing device, and kneaded, A fiber supply step of simultaneously and continuously supplying a plurality of fibers to an upper region of a housing portion having a predetermined volume; a fiber bundling step of bundling the plurality of continuously supplied fibers by a bundling mechanism; a fiber cutting step of cutting the bundled plurality of fibers to a certain length by a laser scanned in a direction intersecting the fiber elongation direction in an upper space region within the housing portion and dropping the fibers downward within the housing portion; a fiber dispersion step of dispersing the cut fibers that have dropped and fallen within the housing portion by physical agitation; a fiber feeding step of forcibly introducing the dispersed cut fibers into the molten thermoplastic resin while increasing the bulk density; and a kneading and discharging step of kneading and discharging the molten thermoplastic resin into which the cut fibers have been fed, wherein in the fiber dispersion step, the cut fibers are agitated by the rotation of a propeller disposed within the dropping region of the cut fibers. Further, in order to achieve the above object, a method for producing a fiber-reinforced thermoplastic resin according to an aspect of the present invention is a method for producing a fiber-reinforced thermoplastic resin in which fibers of a predetermined length are supplied to a molten thermoplastic resin accommodated in a kneading and discharging apparatus and kneaded to produce the fiber-reinforced thermoplastic resin in which the fibers are kneaded, a fiber supply step of simultaneously and continuously supplying a plurality of fibers to an upper region of a housing portion having a predetermined volume; a fiber bundling step of bundling the plurality of continuously supplied fibers by a bundling mechanism; the bundled bundle of fibers in an upper space region within the housing portion by a laser scanned in a direction intersecting the fiber elongation direction up to the middle of the aforementioned bundle of fibers cut to a certain length and dropped downward within the housing portion; a fiber dispersion step of dispersing the cut fibers that have dropped and fallen within the housing portion by physical agitation or an air current; a fiber feeding step of forcibly introducing the dispersed cut fibers into the molten thermoplastic resin while increasing the bulk density; and a kneading and discharging step of kneading and discharging the molten thermoplastic resin into which the cut fibers have been fed, Ta characterized by this.

Advantages of the Invention

[0020] As described above, according to the present invention, since the supplied fibers are cut using a laser, the length adjustment (such as adjusting to a certain length) of the cut fibers can be accurately performed by relatively easy control. Therefore, the lengths of the fibers supplied to the thermoplastic resin can be made uniform, and the kneading state of the cut fibers and the thermoplastic resin can also be made uniform because the feeding position of the cut fibers to the thermoplastic resin is made constant. As a result, a fiber-reinforced thermoplastic resin having desired mechanical properties can be continuously and reliably obtained.

Brief Description of the Drawings

[0021] [Figure 1] It is a schematic configuration diagram of a manufacturing apparatus showing an embodiment of the manufacturing apparatus and manufacturing method of the fiber-reinforced thermoplastic resin of the present invention. [Figure 2] It is an explanatory diagram showing an example of the fiber squeezing mechanism of the manufacturing apparatus of FIG. 1. [Figure 3] It is an explanatory diagram showing an example of the cross roller mechanism of the manufacturing apparatus of FIG. 1. [Figure 4] It is a schematic configuration diagram of the fiber cutting part of the manufacturing apparatus of FIG. 1. [Figure 5] It is an explanatory diagram showing the relationship between the fiber length and volume fraction (cumulative value) of the fibers contained in the fiber-reinforced thermoplastic resin manufactured by the manufacturing apparatus of FIG. 1. [Figure 6] It is an explanatory diagram showing the relationship between the fiber length and volume fraction (cumulative value) of the fibers contained in the fiber continuous input type fiber-reinforced thermoplastic resin manufactured by a conventional manufacturing apparatus. [Figure 7] It is an explanatory diagram showing the state of the fibers contained in the fiber-reinforced thermoplastic resin manufactured by the manufacturing apparatus of FIG. 1. [Figure 8] It is an explanatory diagram showing the state of the fibers contained in the fiber continuous input type fiber-reinforced thermoplastic resin manufactured by a conventional manufacturing apparatus. [Figure 9] It is an explanatory diagram showing the relationship between the tensile elastic modulus and tensile strength of the fiber-reinforced thermoplastic resin manufactured by the manufacturing apparatus of FIG. 1 and a conventional manufacturing apparatus.

Embodiments for Carrying Out the Invention

[0022] An embodiment of the manufacturing apparatus and manufacturing method for fiber-reinforced thermoplastic resin of the present invention will be described in detail below with reference to the drawings. Figure 1 is a schematic diagram of the manufacturing apparatus for fiber-reinforced thermoplastic resin of this embodiment. This manufacturing apparatus is configured to include a kneading and dispensing device (kneading and dispensing unit) 1 for kneading and dispensing molten thermoplastic resin and fibers cut to a certain length. In this specification, "kneading" includes the meaning of "mixing".

[0023] In this example, a single-axis screw conveyor 10 is used as the kneading and dispensing device 1. The screw conveyor 10 in this embodiment is capable of heating and melting its contents. The screw conveyor 10 conveys the contents while stirring and mixing them with the thrust of a rotating spiral continuous screw blade 11, and discharges them from its end. In the kneading and dispensing device 1 of this embodiment, the contents are conveyed from the right to the left in the figure. In this kneading and dispensing device 1, a hopper 12 is provided at the right end of the screw conveyor 10 in the figure, that is, the end on the upstream side in the direction of contents conveyance, and the thermoplastic resin M in pellet form P is supplied to the right end of the screw conveyor 10 by this hopper 12. It is also possible to supply preheated and melted thermoplastic resin M to the screw conveyor 10. The inside of the container of the screw conveyor 10 is almost completely filled with heated and melted thermoplastic resin M (hereinafter also referred to as molten thermoplastic resin), which is transported to the left in the figure and discharged from the left end of the screw conveyor 10 in the figure, that is, the end on the downstream side in the direction of content transport.

[0024] In this embodiment, as will be described later, the rotational speed of the screw blades 11 of the screw conveyor 10 is set to be relatively low. Also, the screw blades 11 do not have the function of cutting fibers and are set in a shape that reduces fiber breakage. In addition to the screw conveyor 10 having multiple screw blades 11, various devices having similar functions such as kneading, (conveying,) and (discharging) can be applied to the kneading and discharging device 1.

[0025] The thermoplastic resin M can be made from polyamides such as polyamide 6, polyamide 11, polyamide 12, polyamide 66, polyamide 610, polyamide 6T, polyamide 6I, polyamide 9T, and polyamide M5T, as well as polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl acetate, polyurethane, polytetrafluoroethylene, acrylonitrile butadiene styrene, acrylic resin, polyacetal, polycarbonate, polyphenylene ether, modified polyphenylene ether, polyester, polyethylene terephthalate, polybutylene terephthalate, cyclic polyolefin, polyphenylene sulfide, polysulfone, polyethersulfone, polyetheretherketone, polyimide, and polyamideimide, which can be used as matrix resins for fiber-reinforced thermoplastic resins.

[0026] Downstream from the molten thermoplastic resin supply position of the kneading and dispensing device 1 consisting of a screw conveyor 10, a fiber to be cut supply device 13 is provided for supplying fibers cut to a certain length to the molten thermoplastic resin M. The fiber to be cut supply device 13 has a storage section 50 of a predetermined volume in the middle of its height. The fiber to be cut supply device 13 is composed of a fiber supply section 2 that simultaneously and continuously supplies a plurality of fibers F to the upper region of the storage section 50, a fiber gathering section 3 that gathers the continuously supplied plurality of fibers F in the upper region of the storage section 50, a fiber cutting section 4 that cuts the gathered plurality of fibers F to a certain length by laser in the upper space region of the storage section 50, a fiber dispersion section 5 that disperses the cut plurality of fibers F within the storage section 50, and a fiber supply section 6 that feeds the dispersed plurality of cut fibers F to the molten thermoplastic resin M in the kneading and dispensing device 1 below the storage section 50. Therefore, the kneading and dispensing device 1 dispenses fiber-reinforced thermoplastic resin in which fibers F, cut to a certain length, are kneaded with molten thermoplastic resin M. Note that the continuous supply of fibers F in the fiber supply unit 2 means continuously supplying fibers F in the direction of fiber elongation before cutting, and not continuously supplying cut fibers over time.

[0027] The fiber supply unit 2 extracts fibers F wound on multiple bobbins (reels, rolls) 20, guides these fibers F with guide rollers 21, and concentrates them in one place, supplying the concentrated fibers F to the fiber bundling unit 3. Therefore, multiple fibers F are supplied simultaneously and continuously from this fiber supply unit 2. The supplied fibers F can include carbon fibers, glass fibers, boron fibers, aramid fibers, polyethylene fibers, metal fibers, and plant fibers, but carbon fibers are typical. The form of the fibers F wound on the bobbins 20 may be continuous fibers such as strands, rovings, or twisted yarns. Examples of continuous fiber lengths include 30m to 15000m. In this example, 12000 carbon fibers with a diameter of 7μm are wound on each bobbin, and these are simultaneously unwound from a total of 48 bobbins and supplied in one place. The fiber supply speed is, for example, 10m / min.

[0028] The fiber focusing unit 3 concentrates multiple fibers F supplied from the fiber supply unit 2 into a small area in order to improve the cutting efficiency by the laser, which will be described later. Optically, "focusing" means that many light rays converge to a single point, but in this embodiment, the term "focusing" is used because, as described above, a large number of fibers F are concentrated in a narrow area. This fiber focusing unit 3 has a focusing mechanism 30 that focuses multiple continuously supplied fibers F in a direction intersecting the fiber elongation direction.

[0029] Figure 2 is a perspective view of a fiber constriction mechanism 31 applied as an example of a focusing mechanism 30. This fiber constriction mechanism 31 focuses multiple fibers F by inserting them into an opening 31a of a predetermined size. The fiber constriction mechanism 31 in this example has a shape similar to a die, which is a receiving mold for a punch, with a circular cross-section through hole formed in the center as the opening 31a. Multiple fibers F are inserted into this opening 31a from top to bottom in the figure. This opening 31a has a frustoconical surface at the top, which is the fiber insertion side, tapering from top to bottom, and below that, a series of cylindrical through holes with a constant inner diameter are formed. Therefore, when multiple fibers F are inserted into this opening 31a from top to bottom, the fibers F are constricted and focused by the frustoconical surface at the top, and then fed out from the cylindrical through holes at the bottom in that state.

[0030] Figure 3 is a perspective view of a cross-roller mechanism 32, which is applied as another example of the focusing mechanism 30. This cross-roller mechanism 32 focuses multiple fibers F by inserting them into a gap 32b formed between multiple rollers 32a whose axes intersect. In this example, the cross-roller mechanism 32 is constructed by using rotatable rollers 32a, with two pairs of parallel rollers 32a arranged horizontally at a relatively small predetermined interval, and arranging them vertically so that their rotation axes are perpendicular to each other. In this cross-roller mechanism 32, multiple fibers F are inserted from the top to the bottom of the figure into the gap 32b between four rollers 32a arranged in a grid pattern in plan view, and the multiple fibers F are focused by this gap 32b and then fed downward. The rollers 32a may be rotationally driven by a driving force, or they may rotate along with the fibers F being inserted. Also, the rollers 32a do not necessarily have to rotate.

[0031] The focusing mechanism 30 of the fiber focusing unit 3 may use either the fiber squeezing mechanism 31 or the cross roller mechanism 32, or both. For example, in Figure 1, only the cross roller mechanism 32 is used as the focusing mechanism, but the fiber squeezing mechanism 31 can also be placed below it. As described above, the fibers F that are focused (converged) in a direction intersecting the fiber elongation direction by this fiber focusing unit 3 are cut by a laser. In this case, by setting the inner diameter of the opening 31a of the fiber squeezing mechanism 31 to be larger than the outer diameter of the fiber F bundled by the cross roller mechanism 32, it is also possible to scan the laser described later in a direction intersecting (orthogonal) to the fiber elongation direction between the upper cross roller mechanism 32 and the lower fiber squeezing mechanism 31 to cut the fibers F.

[0032] The fiber cutting unit 4 of this embodiment is configured with a laser output device 41 that outputs a laser and a laser scanning device 42 that scans the output laser. Existing devices can be used for these devices. Figure 4 shows a schematic configuration of the fiber cutting unit 4 of this embodiment. In this fiber cutting unit 4, the laser scanning device 42 scans a laser in a direction intersecting (orthogonal to) the fiber elongation direction with a plurality of focused (focused) fibers F to cut the fibers F. Laser cutting has attracted attention for cutting thin metal plates and the like, but unlike metals, fibers F such as carbon fibers can be cut with short irradiation times. As a result, in this fiber cutting unit 4, the laser can be scanned in a direction intersecting (orthogonal to) the fiber elongation direction at a high scanning speed to cut the fibers F in a short time. As an example, a plurality of focused fibers F can be cut with a scanning speed of 5 m / s. The scanning speed of this laser can be adjusted (controlled), as with other operating conditions, as will be described later.

[0033] In this embodiment, the length of the fiber F to be cut is measured by a non-contact length measuring instrument 43, and the laser scanning timing and scanning speed are configured to be feedback-controlled so that a desired length is achieved. As can be inferred, the length of the fiber F to be cut can be adjusted (controlled) not only by the laser scanning timing but also by the supply speed of the fiber F from the fiber supply unit 2. Therefore, for example, if the laser scanning speed is restricted in order to reliably cut multiple focused fibers F, it becomes necessary to coordinately control not only the laser scanning timing but also the supply speed of the fiber F. In this embodiment, as will be described later, the configuration is such that such coordinated control can be achieved in order to change the length of the fiber F to be cut in various ways.

[0034] The fiber dispersion unit 5 is configured to include a containment unit 50 that secures a predetermined volume for the dispersion of multiple cut fibers F. The propeller 51 is rotated within this containment unit 50 to disperse the cut fibers F (hereinafter also referred to as cut fibers F). In this embodiment, the bundles of cut fibers F that fall downward into the containment unit 50 after being cut in the fiber cutting unit 4 are separated by a pair of propellers 51 that are facing each other horizontally. Other devices that can do this include screw fans. The cut fibers F can also be dispersed by the airflow generated by the propellers 51, screw fans, blowers, etc.

[0035] As will be described later, in this embodiment, the goal is to make the dispersibility of the fibers to be cut F mixed into the molten thermoplastic resin M as uniform as possible. In Figure 4, the cut fibers F are exaggerated as an image, but immediately after cutting, the fibers to be cut F are in a relatively concentrated state. Dispersing the fibers to be cut F in an earlier stage before supplying them to the molten thermoplastic resin M improves the dispersibility of the fibers to be cut F in the molten thermoplastic resin M compared to supplying the fibers to be cut F in such a relatively concentrated state to the molten thermoplastic resin M.

[0036] The fiber supply unit 6 supplies the fibers to be cut F, which are dispersed in the containment unit 50, to the molten thermoplastic resin M in the containment of the kneading and dispensing device 1. In this embodiment, a fiber introduction mechanism 61 is used to forcibly introduce the dispersed fibers to be cut F into the molten thermoplastic resin M while increasing their bulk density. Since the cut fibers F, such as cut carbon fibers, are lightweight and dispersed in the containment unit 50, the bulk density of the naturally falling fibers F may be low. As will be described later, if the bulk density of the fibers to be cut F is low, it may be difficult to knead them into the molten thermoplastic resin M. Therefore, in this embodiment, the dispersed and falling fibers to be cut F are captured by a fiber introduction mechanism 61 such as a screw-type conveying mechanism, and the bulk density of the fibers to be cut F is increased by the thrust of the screw blades 61a while forcibly introducing them into the molten thermoplastic resin M. By increasing the bulk density of the fibers to be cut F, it is possible to improve the kneadability into the molten thermoplastic resin M. The kneading and dispensing device 1 may be configured to create negative pressure on the kneading and dispensing device 1 side in order to draw the cut fibers F towards the kneading and dispensing device 1 side.

[0037] This fiber-reinforced thermoplastic resin manufacturing apparatus is controlled by a control device 8 located in the control room 7. Each component, including the aforementioned fiber supply unit 2, fiber cutting unit 4, fiber dispersion unit 5, and fiber feeding unit 6, as well as the drive units for the kneading and dispensing device 1 and hopper 12, has its own individual control unit (control panel). The control device 8 in the control room 7 plays a central role in controlling these individual control units, much like a process computer in large-scale manufacturing equipment. This control device 8 manages the coordinated control of the aforementioned fiber cutting unit 4 and fiber supply unit 2. Furthermore, the input / output device 9 provided in this control device 8 allows for adjustment (control) of parameters such as the length of the fibers to be cut F, the amount of material fed to the molten thermoplastic resin M, and the manufacturing speed of the fiber-reinforced thermoplastic resin, i.e., the conveying speed of the screw conveyor 10.

[0038] When the fiber to be cut F is a carbon fiber, the appropriate length of the fiber to be kneaded into the molten thermoplastic resin M is several centimeters (3 mm or more and less than 100 mm). A shorter length of the fiber to be cut improves dispersibility within the molten thermoplastic resin M, thereby improving the rigidity of the molded resin product. On the other hand, a longer length of the fiber to be cut improves its kneadability into the molten thermoplastic resin M, thereby improving the strength of the molded resin product.

[0039] As mentioned above, one objective of the manufacturing apparatus in this embodiment is to improve the dispersibility of the fibers to be cut F within the molten thermoplastic resin M to make it as uniform as possible. If the material and thickness of the fibers F are the same, and the dispersibility of the fibers to be cut F within the molten thermoplastic resin M is uniform, then the mechanical properties of the resin molded product depend on the length of the fibers to be cut F. In the manufacturing apparatus in this embodiment, the length of the fibers to be cut F can be changed in a short time by adjusting the fiber supply speed of the fiber supply unit 2 and the fiber cutting timing of the fiber cutting unit 4. Therefore, as an example, it is possible to obtain fiber-reinforced thermoplastic resins that can achieve various mechanical properties by changing the length of the fibers to be cut F kneaded into the molten thermoplastic resin M from lot (shot) to lot (shot), for example, every 2 to 3 lots.

[0040] Furthermore, unlike mechanically cutting fibers F with blades, laser cutting of fibers F does not involve changes in cutting performance due to deterioration of the blade tip over time. As mentioned above, with very fine fibers F, if the blade tip deteriorates, the cutting performance will decrease significantly, and the fibers F will tend to fray, tangle, and form clumps. When the fibers F to be cut form such tangled clumps, the dispersibility of the fibers F within the molten thermoplastic resin M decreases. In contrast, laser cutting of fibers F, which does not experience a decrease in cutting performance, suppresses fraying of the fibers F to be cut, and stabilizes their dispersibility within the molten thermoplastic resin M.

[0041] Furthermore, in the manufacturing apparatus of this embodiment, as mentioned above, the rotational speed of the screw blades 11 of the screw conveyor 10, which is the kneading and dispensing device 1, is set to a relatively low speed. In conventional two-screw screw conveyors, the rotational speed of the screw blades was set to a relatively high speed in order to cut the continuously supplied fibers F with the screw blades. In contrast, in the screw conveyor 10 of this embodiment, the role of the screw blades 11 is specialized to knead (including conveying) the molten thermoplastic resin M and the fibers F to be cut, so the rotational speed of the screw blades 11 is reduced to prevent further cutting of the fibers F to be cut. For the same reason, the screw conveyor, which was conventionally a two-screw type, can be made into a single-screw conveyor 10 so as not to cut the fibers F to be cut, thereby saving space. In addition, in conventional screw conveyors used as kneading and dispensing devices, it is sometimes necessary to specially add a fiber cutting function to the screw blades, but it is not necessary to add such a function to the screw blades 11 of this embodiment.

[0042] Figure 5 is an explanatory diagram illustrating the relationship between fiber length and volume fraction of fibers contained in fiber-reinforced thermoplastic resin manufactured using the manufacturing apparatus shown in Figure 1, and Figure 6 is an explanatory diagram illustrating the relationship between fiber length and volume fraction of fibers contained in fiber-reinforced thermoplastic resin manufactured using a conventional fiber-feed type manufacturing apparatus. In both figures, the volume fraction is expressed as a cumulative value, starting from the shortest fiber length. In the fiber-reinforced thermoplastic resin of Figure 5, the length of the cut fibers F kneaded into the thermoplastic resin is distributed uniformly within a certain range, which is thought to improve dispersibility and kneadability into the molten thermoplastic resin M, as described above, and as a result, achieve both rigidity and strength in the molded resin product. In contrast, in the fiber-feed type fiber-reinforced thermoplastic resin of Figure 6, there are many extremely short fibers that contribute little to the strength of the molded resin product, and the remaining long cut fibers F create bundles of fibers where stress concentrates, and these bundles of fibers are thought to be the starting point for fracture of the molded resin product.

[0043] Figure 7 is an explanatory diagram showing the state of fibers contained in fiber-reinforced thermoplastic resin manufactured using the manufacturing apparatus shown in Figure 1. Figure 8 is an explanatory diagram showing the state of fibers contained in fiber-reinforced thermoplastic resin manufactured using a conventional manufacturing apparatus with continuous fiber feeding. Both figures are X-ray CT images. Here again, in the manufacturing apparatus shown in Figure 1, the length of the fibers F to be cut, which are kneaded into the thermoplastic resin, is distributed uniformly within a certain range. As is clear from these figures, the variation in fiber length in the fiber-reinforced thermoplastic resin manufactured using the manufacturing apparatus shown in Figure 1 is small, and there are no fibers that are too long, so no fiber bundles are observed. In contrast, fiber bundles (fiber bundles) are scattered throughout the fiber-reinforced thermoplastic resin manufactured using a conventional manufacturing apparatus with continuous fiber feeding. Stress concentrates at these fiber bundles, making them prone to becoming the starting point for fracture of the molded resin product.

[0044] Figure 9 is an explanatory diagram showing the relationship between the tensile modulus and tensile strength of a fiber-reinforced thermoplastic resin manufactured using the manufacturing apparatus shown in Figure 1 (Example) and a fiber-reinforced thermoplastic resin manufactured using a conventional manufacturing apparatus with continuous fiber feeding (Comparative Example). As mentioned above and as shown in the figure, the fiber-reinforced thermoplastic resin manufactured using the manufacturing apparatus shown in Figure 1 has improved tensile modulus (stiffness) and tensile strength compared to the fiber-reinforced thermoplastic resin manufactured using a conventional manufacturing apparatus with continuous fiber feeding.

[0045] As described above, in the manufacturing method and apparatus for fiber-reinforced thermoplastic resin of this embodiment, a plurality of continuously supplied fibers F are cut to a constant length by a laser scanned in a direction intersecting the fiber elongation direction in the upper space region of the housing 50. Since the laser can cut the fibers F even when scanned at high speed, by setting a high laser scanning speed, a plurality of continuously supplied fibers F can be reliably and quickly cut to a constant length. Furthermore, unlike mechanically cutting the fibers F with a blade, the cutting performance of the fibers F by the laser does not deteriorate over time. In other words, a plurality of continuously supplied fibers F can be reliably, stably, and quickly cut to a constant length. The cut fibers F are then fed into the molten thermoplastic resin M in the kneading and dispensing device 1, kneaded, and then discharged, thereby making the kneading state of the thermoplastic resin M and the cut fibers F uniform. Therefore, since the fibers F cut to a constant length are fed into the molten thermoplastic resin M in a dispersed state and discharged in a uniformly kneaded state, the dispersibility of the fibers F in the thermoplastic resin M is also improved. As a result, fiber-reinforced thermoplastic resins with desired mechanical properties can be obtained continuously and reliably.

[0046] Furthermore, the length of the cut fibers F can be adjusted by controlling at least one of the fiber supply rate and the fiber cutting timing of the supplied fibers F. By kneading fibers F of different lengths in this way into a molten thermoplastic resin M, the mechanical properties of the fiber-reinforced thermoplastic resin can be changed. Therefore, fiber-reinforced thermoplastic resins with various mechanical properties can be reliably and easily obtained.

[0047] Furthermore, by setting the length of the cut fibers F to 3 mm or more and less than 100 mm, the dispersibility within the molten thermoplastic resin M and the kneadability into the molten thermoplastic resin M are improved, resulting in a balance between rigidity and strength of the molded resin product.

[0048] Furthermore, by focusing the multiple fibers F that are continuously supplied by the focusing mechanism 30 before being supplied to the fiber cutting section 4, the time required for the laser cutting of the fibers F in the fiber cutting section 4 can be shortened. As a result, the length of the cut fibers F can be made even more uniform.

[0049] Furthermore, the fiber bundling unit 3 includes at least one of a fiber constriction mechanism 31 that bundles multiple fibers F by inserting them into an opening 31a of a predetermined size, and a cross-roller mechanism 32 that bundles multiple fibers by inserting them into a gap 32b formed between multiple rollers 32a whose axes intersect. These are relatively simple configurations that can reliably converge multiple continuously supplied fibers F in a direction intersecting the fiber elongation direction.

[0050] Furthermore, the fibers F cut in the fiber cutting section 4 are dispersed in the storage section 50 by physical agitation by the propeller 51 and by airflow. By pre-dispersing the cut fibers F in this way, the fibers F cut to a certain length are supplied to the molten thermoplastic resin M in a dispersed state, further improving the dispersibility of the fibers F within the thermoplastic resin M after kneading.

[0051] Furthermore, since the cut fibers F are lightweight and dispersed within a predetermined volume of the storage section 50, it may be difficult to stably supply them into the molten thermoplastic resin M by free fall, for example. The lightweight cut fibers F in this dispersed state are supplied by the fiber introduction mechanism 61. capture By forcibly introducing the fibers into the thermoplastic resin M, the amount of fibers introduced into the thermoplastic resin M can be stabilized, thereby stabilizing the mechanical properties of the fiber-reinforced thermoplastic resin. Furthermore, by increasing the bulk density of the fibers to be cut by the fiber introduction mechanism 61, the kneadability into the molten thermoplastic resin M can be improved.

[0052] The above describes a method for manufacturing fiber-reinforced thermoplastic resin and the apparatus thereof according to the embodiment. However, the present invention is not limited to the configuration described in the above embodiment, and various modifications are possible within the scope of the gist of the present invention. For example, in the above embodiment, all of the multiple focused fibers F are cut by a laser, but it is also possible to scan the fiber bundle only partway through, for example, in a direction intersecting (orthogonal to) the fiber elongation direction of the laser. It is also possible to suppress the output of the laser and cut only the portion of the fiber bundle on the laser irradiation side. Furthermore, by performing such control, it is possible to mix long and short fibers F that are cut. Mixing long fibers F with the fibers to be cut improves the ease with which the fibers F to be cut are introduced into the molten thermoplastic resin M. This is because, when the fibers F to be cut are introduced into the molten thermoplastic resin M by the fiber introduction mechanism 61, the longer fibers F are more easily caught in the screw blades 61a, and the shorter fibers F are also transported into the resin as they are dragged along by them. Furthermore, by incorporating cut fibers F of controlled length, it becomes possible to improve the mechanical properties of the fiber-reinforced thermoplastic resin. [Explanation of Symbols]

[0053] 1. Mixing and dispensing device (mixing and dispensing section) 2. Fiber supply section 3. Fiber convergence section 4. Fiber cutting section 5. Fiber dispersion section 6. Fiber feeding section 30 Focusing mechanism 31 Fiber drawing mechanism 31a opening 32 Cross Roller Mechanism 32a Laura 32b Gap 42 Laser scanning device 50 Storage Units 51 Propeller 61 Fiber introduction mechanism F Fiber M Thermoplastic resin

Claims

1. In a fiber-reinforced thermoplastic resin manufacturing apparatus, a predetermined length of fiber is supplied to a molten thermoplastic resin contained in a kneading and dispensing device, and the fiber is kneaded to produce a fiber-reinforced thermoplastic resin, A fiber supply unit that continuously supplies multiple fibers to the upper region of a storage unit of a predetermined volume, A fiber cutting unit that cuts the continuously supplied plurality of fibers to a certain length by a laser scanned in a direction intersecting the fiber elongation direction and drops them downward into the housing unit, A fiber dispersion section is provided at a lower position of the fiber cutting section and disperses the fibers to be cut within the containment section by physical agitation or airflow, A fiber introduction mechanism is provided at a lower position of the fiber dispersion section and forcibly introduces the dispersed fibers to be cut into the molten thermoplastic resin while increasing their bulk density. The system includes a kneading and dispensing unit that kneads the fibers to be cut introduced by the fiber introduction mechanism with the molten thermoplastic resin and then dispenses the mixture. The fiber introduction mechanism is a screw-type conveying mechanism having screw blades that rotate around an axis, and is characterized in that the screw blades capture the fibers to be cut to increase their bulk density, and the thrust from the screw blades forces the fibers to be cut into place.

2. In a fiber-reinforced thermoplastic resin manufacturing apparatus, a predetermined length of fiber is supplied to a molten thermoplastic resin contained in a kneading and dispensing device, and the fiber is kneaded to produce a fiber-reinforced thermoplastic resin, A fiber supply unit that continuously supplies multiple fibers to the upper region of a storage unit of a predetermined volume, A fiber cutting unit that cuts the continuously supplied plurality of fibers to a certain length by a laser scanned in a direction intersecting the fiber elongation direction and drops them downward into the housing unit, A fiber dispersion section is provided at a lower position of the fiber cutting section and disperses the fibers to be cut within the storage section by physical agitation, It comprises a kneading and dispensing unit that kneads the dispersed and dropped cut fibers and the molten thermoplastic resin and then dispenses the mixture, The apparatus for producing fiber-reinforced thermoplastic resin is characterized in that the fiber dispersion section includes a propeller positioned within the area where the fibers to be cut fall, and the fibers to be cut are agitated by the rotation of the propeller.

3. In a fiber-reinforced thermoplastic resin manufacturing apparatus, a predetermined length of fiber is supplied to a molten thermoplastic resin contained in a kneading and dispensing device, and the fiber is kneaded to produce a fiber-reinforced thermoplastic resin, A fiber supply unit that continuously supplies multiple fibers to the upper region of a storage unit of a predetermined volume, A fiber bundling unit that bundles the continuously supplied plurality of fibers by a bundling mechanism, A fiber cutting unit that cuts the bundle of focused fibers at a certain length up to a certain point using a laser scanned in a direction intersecting the fiber elongation direction, and drops the fibers downward into the housing unit, A manufacturing apparatus for fiber-reinforced thermoplastic resin, characterized by comprising a kneading and discharging unit that kneads the fallen cut fibers and the molten thermoplastic resin and discharges the mixture.

4. The apparatus for producing fiber-reinforced thermoplastic resin according to claim 1 or 2, further comprising a fiber bundling section preceding the fiber cutting section, which bundles the continuously supplied plurality of fibers using a bundling mechanism.

5. The fiber bundling section is characterized in that it comprises at least one of the following as the bundling mechanism: a fiber drawing mechanism that inserts and bundles the plurality of fibers into an opening of a predetermined size; and a cross-roller mechanism that inserts and bundles the plurality of fibers into a gap formed between a plurality of rollers whose axes intersect. This is the apparatus for manufacturing fiber-reinforced thermoplastic resin according to claim 3 or 4.

6. The apparatus for producing fiber-reinforced thermoplastic resin according to claim 3, characterized in that a fiber dispersion section is provided at a lower position of the fiber cutting section for dispersing the fibers to be cut within the containment section by physical stirring or airflow.

7. The apparatus for producing fiber-reinforced thermoplastic resin according to claim 2 or 6, characterized in that a fiber introduction mechanism is provided at a lower position of the fiber dispersion section for forcibly introducing the dispersed fibers to be cut into the molten thermoplastic resin while increasing its bulk density.

8. The apparatus for producing fiber-reinforced thermoplastic resin according to any one of claims 1 to 7, characterized in that the length of the cut fibers can be adjusted by controlling at least one of the fiber supply speed by the fiber supply unit and the fiber cutting timing by the fiber cutting unit.

9. The apparatus for producing fiber-reinforced thermoplastic resin according to claim 8, characterized in that the length of the fibers to be cut is 3 mm or more and less than 100 mm.

10. In a method for producing a fiber-reinforced thermoplastic resin, in which fibers of a predetermined length are supplied to a molten thermoplastic resin contained in a kneading and dispensing device, and the fibers are kneaded together to produce a fiber-reinforced thermoplastic resin, A fiber supply step of simultaneously and continuously supplying multiple fibers to the upper region of a storage section of a predetermined volume, A fiber focusing step in which the plurality of fibers supplied continuously are focused by a focusing mechanism, A fiber cutting step in which the multiple focused fibers are cut to a certain length by a laser scanned in the upper spatial region of the housing in a direction intersecting the fiber elongation direction, and the fibers are dropped downward into the housing; A fiber dispersion step in which the cut and falling fibers are dispersed within the containment section by physical agitation or airflow, A fiber feeding step in which the dispersed fibers to be cut are forcibly introduced into the molten thermoplastic resin while increasing their bulk density, The system includes a kneading and dispensing step in which the molten thermoplastic resin into which the fibers to be cut have been supplied is kneaded and then dispensed. The fiber feeding step is performed by a screw-type conveying mechanism having screw blades that rotate around an axis, characterized in that the screw blades capture the fibers to be cut to increase their bulk density, and the thrust from the screw blades forces the fibers to be cut into place.

11. In a method for producing a fiber-reinforced thermoplastic resin, in which fibers of a predetermined length are supplied to a molten thermoplastic resin contained in a kneading and dispensing device, and the fibers are kneaded together to produce a fiber-reinforced thermoplastic resin, A fiber supply step of simultaneously and continuously supplying multiple fibers to the upper region of a storage section of a predetermined volume, A fiber focusing step in which the plurality of fibers supplied continuously are focused by a focusing mechanism, A fiber cutting step in which the multiple focused fibers are cut to a certain length by a laser scanned in the upper spatial region of the housing in a direction intersecting the fiber elongation direction, and the fibers are dropped downward into the housing; A fiber dispersion step in which the cut and falling fibers are dispersed within the containment section by physical agitation, A fiber feeding step in which the dispersed fibers to be cut are forcibly introduced into the molten thermoplastic resin while increasing their bulk density, The system includes a kneading and dispensing step in which the molten thermoplastic resin into which the fibers to be cut have been supplied is kneaded and then dispensed. A method for producing a fiber-reinforced thermoplastic resin, characterized in that, in the fiber dispersion step, the fibers to be cut are stirred by the rotation of a propeller placed within the area where the fibers to be cut fall.

12. In a method for producing a fiber-reinforced thermoplastic resin, in which fibers of a predetermined length are supplied to a molten thermoplastic resin contained in a kneading and dispensing device, and the fibers are kneaded together to produce a fiber-reinforced thermoplastic resin, A fiber supply step of simultaneously and continuously supplying multiple fibers to the upper region of a storage section of a predetermined volume, A fiber focusing step in which the plurality of fibers supplied continuously are focused by a focusing mechanism, A fiber cutting step involves using a laser that scans the bundle of focused fibers in the upper spatial region of the housing in a direction intersecting the fiber elongation direction, cutting the bundle of fibers to a certain length up to a certain point, and dropping it downward into the housing; A fiber dispersion step in which the cut and falling fibers are dispersed within the containment section by physical agitation or airflow, A fiber feeding step in which the dispersed fibers to be cut are forcibly introduced into the molten thermoplastic resin while increasing their bulk density, A method for producing a fiber-reinforced thermoplastic resin, comprising a kneading and discharging step of kneading and discharging the molten thermoplastic resin into which the fibers to be cut have been supplied.

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