JP7849788B2 - Apparatus and method for manufacturing fiber-reinforced thermoplastic resins - Google Patents

Description

This invention relates to a manufacturing apparatus and method for fiber-reinforced thermoplastic resins, and more particularly to a manufacturing apparatus and method for producing fiber-reinforced thermoplastic resins by continuously supplying fibers of a predetermined length to a molten thermoplastic resin and kneading them together.

Examples of manufacturing apparatuses and methods for such fiber-reinforced thermoplastic resins include those described in Patent Document 1 below. The first material described in Patent Document 1 is called a fiber-reinforced thermoplastic resin produced by a continuous fiber feeding method, and is attracting attention because it can continuously produce fiber-reinforced thermoplastic resins in a short time, whereas the manufacturing process is generally complex and time-consuming. The manufacturing apparatus and method for producing this first material involves, for example, supplying molten thermoplastic resin to the upstream end in the content conveying direction of a kneading (mixing) and delivery device equipped with twin screw blades.

This kneading and dispensing device continuously receives multiple fibers, such as carbon fibers, drawn from multiple bobbins, at the same end. The fibers continuously supplied to this device are pulled in by the thrust of a screw blade within the device, cut by the screw blade, and then kneaded with a molten thermoplastic resin by the screw blade. The fiber-reinforced thermoplastic resin, containing relatively long fibers, is then discharged, for example, from the downstream end of the kneading and dispensing device in the content transport direction. Maintaining a heated, i.e., molten state, it is loaded into a mold in a press device and subjected to high-speed press molding to produce a resin molded product.

Furthermore, Patent Document 1 discloses the mixing of a fiber-reinforced thermoplastic resin (second material), manufactured separately from the first material, into a fiber-reinforced thermoplastic resin (first material) in order to improve the overall physical properties of the fiber-reinforced thermoplastic resin. This second material is obtained by cutting fibers impregnated with thermoplastic resin. 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.

Japanese Patent Publication No. 2019-147374 Japanese Patent Publication No. 2004-11030

However, in the manufacturing apparatus and method for the fiber-reinforced thermoplastic resin 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 uniform after cutting 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.

Furthermore, variations occur in the timing of fiber cutting by the screw blades after the continuous fibers are supplied, resulting in an uneven mixing state between the thermoplastic resin and the fibers. If the mixing state between the thermoplastic resin and 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 scattering or being scattered, so "dispersibility" is used to describe the degree of scattering.

In other words, conventional fiber-reinforced thermoplastic resin manufacturing apparatuses and methods using continuous fiber feeding make it difficult to obtain fiber-reinforced thermoplastic resins with desired mechanical properties.

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 previously manufactured first material, a fiber-injection type fiber-reinforced thermoplastic resin. Since this second material is made from fibers impregnated with thermoplastic resin and then cut, the cutting length is considered adjustable. However, it requires a separate manufacturing process from the first material, hindering the overall continuity of the manufacturing process. Additionally, challenges remain, such as the inability to determine the mechanical properties and achieve stability of the manufactured fiber-injection type fiber-reinforced thermoplastic resin.

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 using a continuous fiber feeding method, there is a risk that the carbon fiber bundles may become frayed due to blade deterioration during 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.

This invention has been made in view of the above-mentioned problems, and its object is to provide a manufacturing apparatus and method for fiber-reinforced thermoplastic resins that can continuously and reliably produce fiber-reinforced thermoplastic resins with desired mechanical properties.

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,
The device is characterized by comprising: 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 focusing unit that focuses the plurality of fibers that are continuously supplied by a focusing mechanism; a fiber cutting unit that cuts the bundle of focused fibers to a certain length partway through the bundle of fibers using a laser scanned in a direction intersecting the fiber elongation direction and drops it downward into the storage unit; and a kneading and dispensing unit that kneads the dropped cut fibers and the molten thermoplastic resin and dispenses the mixture.

Furthermore, another component of the above-mentioned fiber-reinforced thermoplastic resin manufacturing apparatus is characterized by the ability to adjust the length of the cut fibers 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.

A further configuration of the above-described fiber-reinforced thermoplastic resin manufacturing apparatus is characterized by the length of the fibers to be cut being 3 mm or more and less than 100 mm.

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

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.

A further configuration of the above-described fiber-reinforced thermoplastic resin manufacturing apparatus is characterized by the inclusion of a fiber dispersion section at a lower position of the fiber cutting section, which disperses the fibers to be cut within the containment section by physical stirring or airflow.

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.

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,
The invention provides 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 converging step of converging the plurality of fibers that are continuously supplied by a converging mechanism; a fiber cutting step of cutting the converged 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 fibers that have fallen within the storage section by physical stirring; 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 mixture, wherein in the fiber dispersion step, the cut fibers are stirred by the rotation of a propeller positioned within the area where the cut fibers fall.
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 invention is characterized by comprising: 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 converging step of converging the plurality of fibers that are continuously supplied by a converging mechanism; a fiber cutting step of cutting the bundle of fibers to a certain length partway through the bundle of fibers by a laser scanned in the upper spatial region of the storage section in a direction intersecting the fiber elongation direction, and dropping it downward into the storage section; a fiber dispersion step of dispersing the cut fibers that have fallen 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 dispensing step of kneading the molten thermoplastic resin into which the cut fibers have been fed and dispensing it.

As described above, according to the present invention, since the supplied fibers are cut using a laser, the length of the fibers to be cut (such as adjusting them to a constant length) can be accurately controlled relatively easily. Therefore, the length of the fibers supplied to the thermoplastic resin can be made uniform, and the mixing state of the fibers to be cut and the thermoplastic resin can also be made uniform because the feeding position of the cut fibers into the thermoplastic resin is kept constant. This makes it possible to continuously and reliably obtain fiber-reinforced thermoplastic resins with desired mechanical properties.

This is a schematic diagram of a manufacturing apparatus showing one embodiment of the manufacturing apparatus and manufacturing method for fiber-reinforced thermoplastic resin of the present invention. Figure 1 is an explanatory diagram showing an example of the fiber drawing mechanism of the manufacturing apparatus. Figure 1 is an explanatory diagram showing an example of the cross-roller mechanism of the manufacturing apparatus. Figure 1 is a schematic diagram of the fiber cutting section of the manufacturing apparatus. This diagram illustrates the relationship between fiber length and volume fraction (cumulative value) of fibers contained in the fiber-reinforced thermoplastic resin manufactured using the manufacturing apparatus shown in Figure 1. This diagram illustrates the relationship between fiber length and volume fraction (cumulative value) of fibers contained in fiber-reinforced thermoplastic resin produced using a conventional manufacturing device. This is an explanatory diagram showing the state of the fibers contained in the fiber-reinforced thermoplastic resin manufactured using the manufacturing apparatus shown in Figure 1. This is an explanatory diagram showing the state of fibers contained in fiber-reinforced thermoplastic resin produced using a conventional manufacturing device. Figure 1 is an explanatory diagram showing the relationship between the tensile modulus and tensile strength of fiber-reinforced thermoplastic resin produced by the manufacturing apparatus and conventional manufacturing apparatus.

Below, an embodiment of the manufacturing apparatus and manufacturing method for fiber-reinforced thermoplastic resin of the present invention will be described in detail 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 "combination."

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 diagram and discharged from the left end of the screw conveyor 10, that is, the end on the downstream side in the direction of content transport.

In this embodiment, as will be described later, the rotational speed of the screw blades 11 of the screw conveyor 10 is set to a relatively low level. Furthermore, the screw blades 11 do not have the function of cutting fibers and are shaped to reduce fiber breakage. In addition to the screw conveyor 10 with multiple screw blades 11, various other devices with similar functions such as kneading, (conveying,) and (discharging) can be applied to the kneading and discharging device 1.

The thermoplastic resin M can be applied as a matrix resin for fiber-reinforced thermoplastic resins, and includes 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.

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. This fiber to be cut supply device 13 has a storage section 50 of a predetermined volume in the middle of its height. This 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 sends 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 uncut fibers F in the fiber elongation direction, and not continuously supplying cut fibers over time.

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. The concentrated fibers F are then supplied 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 strands of 7μm diameter carbon fiber are wound on each bobbin, and these are simultaneously unwound from a total of 48 bobbins and supplied in a concentrated manner to one place. The fiber supply speed is, for example, 10m/min.

The fiber focusing unit 3 concentrates multiple fibers F supplied from the fiber supply unit 2 into a small area, with the aim of improving the laser cutting efficiency described later. While "focusing" optically means many light rays converging at a single point, 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 the continuously supplied multiple fibers F in a direction intersecting the fiber elongation direction.

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, a punch receiving mold, with a circular cross-section through-hole formed as the opening 31a in the center. Multiple fibers F are inserted into this opening 31a from top to bottom in the figure. The opening 31a has a frustoconical surface at the top, which is the fiber insertion side, tapering downwards from top to bottom. Below this, 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, they are constricted and focused by the upper frustoconical surface, and then fed out from the lower cylindrical through-holes in that state.

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. The multiple fibers F are focused by this gap 32b and then fed downwards. The rollers 32a may be rotationally driven by a driving force, or they may rotate in conjunction with the inserted fibers F. Furthermore, the rollers 32a do not necessarily have to rotate.

The fiber 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 focused (concentrated) in a direction intersecting the fiber elongation direction by this fiber focusing unit 3 are cut by a laser. At that time, 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 concentrated by the cross-roller mechanism 32, it is 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. Furthermore, a transport mechanism (not shown), such as a transport roller for maintaining and transporting multiple fibers F in a concentrated state, may be interposed between the fiber focusing unit 3 and the fiber cutting unit 4.

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 components. 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 to cut a plurality of focused (focused) fibers F. While laser cutting has attracted attention for cutting thin metal plates and the like, unlike metals, fibers F such as carbon fibers can be cut with short irradiation times. As a result, this fiber cutting unit 4 can cut fibers F in a short time by scanning the laser at a high scanning speed in a direction intersecting (orthogonal to) the fiber elongation direction. As an example, a plurality of focused fibers F can be cut at 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.

In this embodiment, the length of the fiber F to be cut is measured by a non-contact length measuring device 43, and the laser scanning timing and scanning speed are configured to be feedback-controlled so that the 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 designed to enable such coordinated control in order to change the length of the fiber F to be cut in various ways.

The fiber dispersion unit 5 is configured with a containment unit 50 that secures a predetermined volume for dispersing the multiple cut fibers F. Within this containment unit 50, a propeller 51 is rotated 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 horizontally opposed propellers 51. Other such devices include screw fans. Furthermore, the cut fibers F can also be dispersed by airflow generated by the propellers 51, screw fans, blowers, etc.

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 for illustrative purposes, but immediately after cutting, the fibers F are in a relatively concentrated state. Dispersing the fibers F in an earlier stage before supplying them to the molten thermoplastic resin M improves the dispersibility of the fibers F within the molten thermoplastic resin M compared to supplying them in this relatively concentrated state.

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. To draw the cut fibers F towards the kneading and dispensing device 1, the kneading and dispensing device 1 may be configured to create negative pressure.

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, fiber feeding unit 6, as well as the kneading and dispensing device 1 and the 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 a large-scale manufacturing facility. 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.

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 fiber length improves dispersibility within the molten thermoplastic resin M, resulting in improved rigidity of the molded resin. Conversely, a longer fiber length improves kneadability into the molten thermoplastic resin M, resulting in improved strength of the molded resin.

As described 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 article depend on the length of the fibers to be cut F. In this manufacturing apparatus, 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 capable of achieving 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.

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 earlier, with very fine fibers F, if the blade tip deteriorates, the cutting performance decreases significantly, and the fibers F 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, resulting in stable dispersibility within the molten thermoplastic resin M.

Furthermore, in this embodiment of the manufacturing apparatus, as described 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 twin-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. For similar reasons, the conventional twin-screw conveyor can be replaced with a single-screw conveyor 10 to prevent further cutting of the fibers F, thereby saving space. Also, in conventional screw conveyors used as kneading and dispensing devices, it may be necessary to specially add a fiber cutting function to the screw blades in some cases, but the screw blades 11 of this embodiment do not need to have such a function.

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 manufacturing apparatus with continuous fiber feeding. 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. As a result, as mentioned above, the dispersibility and kneadability into the molten thermoplastic resin M are improved, and consequently, it is thought that both rigidity and strength of the molded resin product are achieved. In contrast, in the fiber-reinforced thermoplastic resin of Figure 6, there are many extremely short fibers that contribute little to the strength of the molded resin product. Furthermore, 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.

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 within the fiber-reinforced thermoplastic resin manufactured using the manufacturing apparatus in Figure 1 is small, and there are no excessively long fibers, 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 in the molded resin product.

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

In this embodiment of the method and apparatus for manufacturing fiber-reinforced thermoplastic resin, 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 laser cutting performance of the fibers F does not deteriorate over time. That is, 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 ensuring a uniform kneading state between the thermoplastic resin M and the cut fibers F. 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 within the thermoplastic resin M is also improved. As a result, fiber-reinforced thermoplastic resins with the desired mechanical properties can be obtained continuously and reliably.

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

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 article.

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

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 components, with their relatively simple configuration, can reliably converge multiple continuously supplied fibers F in a direction intersecting the fiber elongation direction.

Furthermore, the fibers F cut in the fiber cutting section 4 are dispersed within the storage section 50 by physical agitation using 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.

Furthermore, since the cut fibers F are lightweight and dispersed within the 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. By capturing these dispersed, lightweight cut fibers F with the fiber introduction mechanism 61 and forcibly introducing them into the thermoplastic resin M, it becomes possible to stabilize the amount of fibers introduced into the thermoplastic resin M, thereby stabilizing the mechanical properties of the fiber-reinforced thermoplastic resin. In addition, by increasing the bulk density of the cut fibers F with the fiber introduction mechanism 61, the kneadability into the molten thermoplastic resin M can be improved.

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 to be cut are more easily caught in the screw blades 61a, and the shorter fibers F to be cut are also transported into the resin as they are dragged along by them. Furthermore, by incorporating cut fibers F of controlled lengths, it becomes possible to improve the mechanical properties of the fiber-reinforced thermoplastic resin.

1. Mixing and dispensing device (mixing and dispensing section)
2 Fiber supply unit 3 Fiber bundling unit 4 Fiber cutting unit 5 Fiber dispersion unit 6 Fiber feeding unit 30 Bundling mechanism 31 Fiber squeezing mechanism 31a Opening 32 Crossing roller mechanism 32a Roller 32b Gap 42 Laser scanning device 50 Storage unit 51 Propeller 61 Fiber introduction mechanism F Fiber M Thermoplastic resin

Claims (12)

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 . 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 . 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. 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. 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 . 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. 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. 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. 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. 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 a direction intersecting the fiber elongation direction in the upper spatial region of the housing and 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 involves forcibly introducing the dispersed fibers to be cut 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 . 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 a direction intersecting the fiber elongation direction in the upper spatial region of the housing and 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. 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 dispensing step of kneading the molten thermoplastic resin to which the fibers to be cut have been supplied and dispensing the kneaded resin.