Mixing machine and mixing method

Abstract

The present invention provides a kneader equipped with a roving mechanism that allows for the quantitative supply of fiber bundles, regardless of the kneading conditions, during the kneading of a plasticized thermoplastic resin and a fibrous filler. [Solution] A kneader that controls the screw rotation speed of the kneader based on the weight change of the roving. Preferably, the weight change of the roving is measured using a loss-in-weight formula to control the dispensing of fiber bundles and the supply of thermoplastic resin. Preferably, the weight decrease of the fiber bundles of the roving is linked to the supply of thermoplastic resin to the kneader.

Description

Technical Field

[0001] The present invention relates to a kneader and a kneading method.

Background Art

[0002] In order to improve properties such as the strength of a thermoplastic resin, a fibrous filler is mixed with the thermoplastic resin. A kneader is used to produce a thermoplastic resin composition reinforced with a fibrous filler. Reinforcing fibers such as carbon fibers and glass fibers are bundled with dozens to hundreds of single fibers into strands, and dozens of such strands are twisted together into a fiber bundle and then into roving. The reinforcing fibers are provided in a state where such roving is wound around a cylindrical roll. As a method for introducing roving into a kneader, there are a method of introducing it from an opening provided on a screw, such as a vent port, and a method of introducing it from a side feeder. In either case, the driving force for introduction is due to the rotation of the screw.

[0003] Citation Document 1 discloses an extruder in which roving-like reinforcing fibers are conveyed in a cylinder of an extruder by a screw. However, in this extruder, it is difficult to uniformly disperse the reinforcing fibers in the thermoplastic resin.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] To provide a kneader (or extruder) equipped with roving that can supply a fiber bundle quantitatively without depending on kneading conditions in kneading a plasticized thermoplastic resin and a fibrous filler.

Means for Solving the Problems

[0006] In the kneader (or extruder) of the present invention, the feeding of roving fiber bundles into the kneader (supply of fiber bundles) is controlled by the change in the weight of the roving. The driving force for feeding the fiber bundles does not depend on the rotation of the screw.

[0007] In the kneading method (or extrusion method) of the present invention, the screw rotation speed of the kneader (or the rotation speed of the roving) is controlled based on a change in the amount of roving fiber bundles supplied (change in the weight of the remaining roving). The amount of fiber bundles supplied is controlled by the screw rotation speed (or roving rotation speed) of the kneader, and the actual change in the amount of fiber bundles supplied (weight change data) is used to determine the screw rotation speed (or roving rotation speed). Changes in the supply of fiber bundles (i.e., changes in the weight of remaining roving) can be measured using the loss-in-weight formula. The amount of fiber bundles supplied to the kneader and the screw rotation speed of the kneader can be controlled by changing the weight of the roving. In this invention, "kneader" may be replaced with "extruder," and "kneading method" may be replaced with "extrusion method."

[0008] This invention relates to the following: [1] A kneader that controls the screw rotation speed by changing the weight of the roving. [2] The kneader described in [1] controls the supply of roving fiber bundles and thermoplastic resin by measuring the weight change of the roving using a loss-in-weight formula. [3] The kneader described in [1] controls the amount of roving fiber bundles supplied to the kneader by changing the weight of the roving. [4] The kneader according to [1], which measures the weight of the fiber bundles lost from the roving as they are fed out by the roving device using a measuring instrument, compares whether the trend of the decrease in this weight matches a preset target value of the fed-out weight (feed-out sequence), and increases or decreases the rotational speed of the roving and / or the kneader, which are the manipulated variables, in a direction that reduces the deviation between the two, thereby increasing or decreasing the weight of the fiber bundles fed out by the roving device. [5] The kneader according to [1], which is provided with pulleys or tubes to support the fiber bundles of roving. [6] A kneader as described in [1], in which fiber bundles are fed out from beneath the roving. [7] A kneading method comprising controlling the screw rotation speed of a kneader by changing the weight of the roving. [Effects of the Invention]

[0009] The kneader of the present invention allows for the quantitative supply of fiber bundles regardless of the kneading conditions. Therefore, in the kneading of thermoplastic resin and fibrous filler, the dispersion of reinforcing fibers in the thermoplastic resin is uniform. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram showing one embodiment of the kneading machine of the present invention. [Figure 2] This is a schematic diagram showing another embodiment of the kneader of the present invention, in which the connection between the roving and the roving supply port differs from that shown in Figure 1. [Figure 3] This is a schematic diagram showing another embodiment of the kneading machine of the present invention. [Figure 4] This schematic diagram shows a configuration similar to Figure 1, except that pipes are used. [Modes for carrying out the invention]

[0011] The kneader includes a cylinder (kneader body), a fiber supply port, a resin supply port, and a screw, and additionally may include a roving device and a resin supply device. The kneader system includes a roving device and a resin supply device in addition to the kneader. In the kneader, the kneader body (cylinder) has a conveying zone and a kneading zone. The number of each of the conveying zone and the kneading zone may be one, but generally it is preferably at least two. When there are two or more conveying zones or kneading zones, the conveying zones and the kneading zones are alternately positioned.

[0012] A fiber bundle is supplied from a roving device having roving to the kneader body (cylinder). The fiber bundle is defibrated into fibers, and the thermoplastic resin and the fibers (fiber-like filler) are mixed.

[0013] The roving device having roving is preferably of the loss-in-weight type. The roving device is preferably a weight-type feeder using the loss-in-weight type. The roving device preferably includes a loss-in-weight type continuous metering feeder. The weight change of the roving fiber bundle is controlled by the weight change of the thermoplastic resin in the cylinder, for example, by the supply of the thermoplastic resin to the kneader. For example, the weight change of the roving fiber bundle is controlled by the screw rotation speed of the kneader.

[0014] In the present invention, a plurality of rovings may be managed on one weighing platform, or a plurality of rovings may be managed on individual weighing platforms. Since the control is not complicated, it is preferable to install a plurality (2 to 12 or 4 to 8, for example 6) of rovings on one weighing platform.

[0015] The control unit of the roving device can feedback control the weight of fiber bundles dispensed per unit time by the roving device using a loss-in-weight method (cumulative weight loss method). Control can be performed by, for example, PI control, PID control (a control method that adds differential and integral control to proportional control), MPC control, etc. The control of the fiber bundles (roving) and the control of the resin may be performed separately or in conjunction.

[0016] One specific example of control (e.g., PID control) is to measure the weight of the fiber bundles lost from the roving as they are fed out by the roving device using a measuring instrument, compare the trend of this weight decrease with a preset target value for the fed weight (feed sequence), and increase or decrease the rotation speed of the roving and / or the kneader, which are the manipulated variables, in a direction that reduces the deviation between the two, thereby increasing or decreasing the weight of the fiber bundles fed out by the roving device. The measurement interval for measuring the weight of the lost fiber bundles (i.e., the change in the weight of the roving) may be 0.1 seconds to 60 seconds, 0.2 seconds to 10 seconds, 0.3 seconds to 5 seconds, or 0.5 seconds to 2 seconds. In PID control, it is preferable to pre-set the proportional gain, integral gain, and differential gain through preliminary testing, etc. It is also preferable to optimize the proportional gain, integral gain, and differential gain as needed during actual operation.

[0017] "Roving" refers to a bundle of fibers that is typically twisted, and specifically a bundle of fibers that is wound around a bobbin or similar object. The shape of the fiber bundle in roving may be circular (perfectly round or elliptical) or flat. The thickness of the fiber bundle may be 100 to 10,000 tex or 500 to 5,000 tex, for example, 1,200 tex or 2,400 tex. The supply port for supplying the fiber bundles to the kneader's cylinder may be located upstream, midstream, or downstream of the cylinder. However, it is preferable that the location for introducing the roving fiber bundles be close to the downstream discharge port (of the kneader) and / or close to the kneading zone, as this suppresses breakage of the fibrous filler.

[0018] The fiber bundles are fed from the roving to the kneader. Generally, the fiber bundles are fed into the kneader by being caught in the kneader's screw. There may be one or more supply ports (e.g., 2 to 6 or 2 to 4) for supplying fiber bundles to the cylinder. One roving may be connected to one supply port, or multiple rovings (e.g., 2 to 10) may be connected to one supply port. When there are many rovings (e.g., 4 or more), it is preferable to supply them from 2 to 4 supply ports.

[0019] The fiber bundles are fed out from either the inside or outside of the roving and supplied to the feed port. It is preferable to feed the fiber bundles out from the inside of the roving because this reduces the stress on the roving. A roving may be connected to another roving, rather than being connected to the supply port. This allows for the supply of fiber bundles over a longer period of time. When rovings are connected, it is preferable that the outer fiber bundle of one roving is connected to the inner fiber bundle of the next roving.

[0020] The fiber bundles may be fed out from above or below the roving. The angle at which the fiber bundle is unfurled from the roving is not particularly limited. However, it is preferable to install a fiber bundle support (e.g., a tube) on the top (or bottom) of each roving so that the unfurling angle from inside the roving is constant for each roving. If the angle exceeds a certain level when the roving is unfurled (from the inside or outside), stress will be applied to the roving, which may lead to large errors in weight measurement or cause the roving to tip over or shift, which is undesirable. The angle at which the fiber bundle is unfurled from the roving may be 0 to 90 degrees with respect to the vertical direction of the roving (perpendicular to the direction in which the fiber bundle is wound), for example, 0 to 50 degrees or 0 to 30 degrees. The support may be a tube, which may be a straight tube or a curved tube.

[0021] The mixing machine may have a single shaft or multiple shafts (two or more shafts). The diameter of the kneading machine cylinder may be 1 to 100 cm or 2 to 10 cm. The length of the kneading machine cylinder may be 50 to 2000 cm or 100 to 1000 cm. The rotational speed of the mixing machine's screw may be 10-2000 rpm or 100-1000 rpm, for example, 450 rpm.

[0022] The present invention will be described in detail below with reference to the drawings.

[0023] Figure 1 is a schematic diagram showing one embodiment of a kneader. The kneader (or kneading system) 100 comprises a cylinder (kneader body) 112, a fiber supply port 114, a resin supply port 116, a screw 118, a roving device 120, and a resin supply device 130. The roving device 120 has a roving 122 and a weighing platform 124 for weighing the roving 122, and a fiber bundle 126 is fed out from the inside of the roving 122. The direction in which the fiber bundle 126 is fed out from the inside of the roving 122 is at a certain angle (e.g., 5 to 70 degrees) with the vertical direction Z1. The fibers and resin flow in the direction of the arrows, with the right side being upstream and the left side being downstream in the diagram.

[0024] As shown in the figure, there may be one roving on a weighing platform, but generally, it is preferable to have multiple rovings on a weighing platform (e.g., 2 to 12) (not shown). There may be multiple weighing platforms, and each of the multiple weighing platforms may support one roving.

[0025] The fiber supply port 114 is located downstream of the resin supply port 116. This shortens the time the fibers travel through the cylinder, thereby suppressing fiber breakage. In Figure 1, there is one fiber supply port 114, but there may be two or more fiber supply ports 114 (for example, 2 to 4). Generally, two or more fiber supply ports are located downstream of the resin supply port 116, and the distance between one fiber supply port and another may be close or far apart.

[0026] Support members (e.g., pulleys and tubes) may be provided to support the fiber bundles. Although pulleys 142 and 144 supporting the fiber bundles are located between the roving device 120 and the fiber supply port 114, the pulleys can be omitted. There may be some slack in the fiber bundles between the roving device 120 and the fiber supply port 114, which reduces the stress on the fiber bundles.

[0027] Figure 2 is a schematic diagram showing another embodiment of a kneader in which the angle of the fiber bundle at the pulley is approximately 90 degrees. The kneader 200 comprises a cylinder (kneader body) 212, a fiber supply port 214, a resin supply port 216, a screw 218, a roving device 220, and a resin supply device 230. The roving device 220 has rovings 222 and 223, and a weighing platform 224 for weighing the rovings 222 and 223, and the fiber bundle 226 is fed out from the inside of the roving 222. The direction in which the fiber bundle 226 is fed out from the inside of the roving 222 is approximately the same as the vertical direction Z2 of the roving. The fibers and resin flow in the direction of the arrows, with the right side being upstream and the left side being downstream in the drawing. The fiber bundle of roving 223 may be connected to the supply port 214 without passing through roving 222 (not shown). Alternatively, the inner fiber bundle of roving 223 is connected to the outer fiber bundle of roving 222, and the fiber bundle of roving 223 begins to be unfed after the fiber bundle of roving 222 has finished being unfed.

[0028] Figure 3 is a schematic diagram (a schematic partial cross-sectional view) showing another embodiment of the kneading machine of the present invention. The kneader 300 comprises a cylinder (kneader body) 312, a supply port 314, a screw 318, a roving device 320, and a resin supply device 330. The supply port 314 is a supply port for supplying fiber bundles and resin to the cylinder 312. The roving device 320 has a roving 322 and a weighing platform 324 for weighing the roving 322, and fiber bundles 326 are fed out from the inside of the roving 322. The direction in which the fiber bundles 326 are fed out from the inside of the roving 322 is approximately the same as the vertical direction Z3 of the roving. The direction in which the fiber bundles 326 are fed out from the inside of the roving 322 may be at a certain angle (e.g., 5 to 70 degrees) (or e.g., 20 degrees or less) with respect to the vertical direction Z3. The fibers and resin flow in the direction of the arrows, with the right side being upstream and the left side being downstream in the drawing. There may be one roving on a weighing platform. In general, it is preferable to have multiple rovings on a weighing platform (e.g., 2 to 12) (not shown). There may be multiple weighing platforms, and each of the multiple weighing platforms may support one roving. As shown in the diagram, if the fiber supply port is located below the roving device, the stress applied to the roving when it is fed out (for example, from the inside of the roving) is reduced, resulting in more accurate measurement of the roving weight.

[0029] Figure 4 is a schematic diagram showing the same configuration as Figure 1, except that tubes are used. Tubes 452, 454, and 464 function as supports to guide the fiber bundle. Tubes 452, 454, and 464 are fixed to a weighing platform 424 or a cylinder 412, etc. Tubes 452, 454, and 464 prevent large vibrations of the fiber bundle. Tubes 452, 454, and 464 are shown as straight tubes, but they may be curved tubes. The kneader 400 includes a cylinder (kneader body) 412, a supply port 414, a screw 418, a roving device 420, and a resin supply device 430. The fiber supply port 414 supplies fiber bundles to the cylinder 412, and the resin supply port 416 supplies resin to the cylinder 412. The roving device 420 has a roving 422 and a weighing platform 424 for weighing the roving 422, from which fiber bundles 426 are fed out. The direction in which the fiber bundles 426 are fed out from the inside of the roving 422 is approximately the same as the vertical direction Z4 of the roving. The fibers and resin flow in the direction of the arrows, with the right side being upstream and the left side being downstream in the diagram. Pulleys 442 and 444, which support the fiber bundles, are located between the roving device 420 and the supply port 414, but the pulleys can be omitted. Even if the pulleys are omitted, the fiber bundles are supported by tubes 452, 454 and 464.

[0030] There are no limitations on the fibrous filler and thermoplastic resin used in the method according to this embodiment, but specific examples are shown below.

[0031] [Fibrous filler] The fibrous filler is, for example, a bundle of fibers in which multiple monofilaments are bundled together with a consolidating agent or the like. Bundles of fibers bundled with a consolidating agent or the like offer excellent handling during kneading. There are no particular restrictions on the number of monofilaments that make up the bundle of fibers, but for example, there may be 300 to 3000 or 1100 to 2200. The fibrous filler may be supplied to a twin-screw compounding machine by continuously feeding bundles of monofilaments as rovings, or by feeding them to a twin-screw compounding machine in the form of chopped strands after cutting the rovings. From the viewpoint of transport and handling, chopped strands are preferred for the fibrous filler.

[0032] Examples of fibrous fillers include glass fibers, carbon fibers, aramid fibers, and basalt fibers. Fibrous fillers may be used individually or in combination of two or more types.

[0033] (Glass fiber) The fiber diameter of the monofilament forming the fiber bundle of glass fibers is not particularly limited, but for example, those in the range of 6 to 20 μm are preferred, and those with diameters of 6 μm, 10 μm, and 13 μm are commonly available on the market.

[0034] Fiber diameter can be determined, for example, by cutting a fiber perpendicular to its direction of fiber, observing the cross-section under a microscope to measure its diameter, and calculating the number average of the diameters of 100 or more fibers.

[0035] (Carbon fiber) The type of carbon fiber is not particularly limited, but examples include PAN (polyacrylonitrile) carbon fiber made primarily from acrylonitrile, pitch carbon fiber made primarily from tar pitch, and rayon carbon fiber. For example, PAN carbon fiber is preferred from the viewpoint of compositional purity and uniformity. The method for manufacturing the carbon fiber is not particularly limited.

[0036] The fiber diameter of the monofilament forming the carbon fiber bundle may be, for example, greater than 2 μm and less than or equal to 15 μm, or between 3 and 12 μm, or between 4 and 10 μm. When the fiber diameter is 2 μm or less, the stiffness of the fiber tends to decrease. When the fiber diameter exceeds 15 μm, the aspect ratio of the fiber (ratio of length (L) to thickness (D): L / D) decreases, which may reduce stiffness and heat resistance.

[0037] As for PAN-based carbon fibers, for example, products such as "Pyrophil" manufactured by Mitsubishi Rayon, "Torayca" manufactured by Toray Industries, or "Besfight" manufactured by Toho Tenax can also be used.

[0038] As pitch-based carbon fibers, for example, products such as "DiaLead" manufactured by Mitsubishi Plastics, Inc., "DonaCarbo" manufactured by Osaka Gas Chemical Co., Ltd., or "Crecca" manufactured by Kureha Chemical Co., Ltd. can also be used.

[0039] (Aramid fiber) The aramid constituting the aramid fiber is preferably meta-aramid, para-aramid, or copolymerized para-aramid, more preferably para-aramid or copolymerized para-aramid, and even more preferably copolymerized para-aramid. Here, para-aramid refers to an aramid having a structure in which each benzene ring is linearly linked through an amide group (CONH).

[0040] Specific examples of aramid fibers include meta-aramid fibers such as NOMEX (product name from DuPont), TEIJINCONEX (product name from Teijin Limited of Japan), METASTAR (product name from Yantai of China), and X-FIPER (product name from SRO Group of China), as well as TWARON (product name from Teijin Limited), KEVLAR (product name from DuPont), KERMEL TECH (product name from Kermel), and HERACRON (product name from Kolon Industries).

[0041] The fiber diameter of the monofilaments forming the aramid fiber bundle may be, for example, 1 to 50 μm, 3 to 30 μm, or 5 to 15 μm, from the viewpoint of improving the bending strength and impact resistance of the resulting resin composition.

[0042] (Basalt fiber) Basalt fibers are produced by melting basalt, a mineral, in a melting furnace and spinning it into fibers. They are usually composed solely of basalt. Basalt fibers typically contain 55-65% by mass of silicon dioxide (SiO2), 15-20% by mass of aluminum oxide (Al2O3), and iron oxide (FeO, Fe2O3), etc. Due to the recrystallization process that occurs during melt spinning, basalt fibers tend to have a more homogeneous crystalline structure than other types of rock wool.

[0043] The fiber diameter of the monofilaments forming the fiber bundle of basalt fibers may be, for example, 2 to 15 μm, 6 to 13 μm, or 9 to 13 μm.

[0044] The fibrous filler is preferably glass fiber or carbon fiber.

[0045] The fibrous filler may be surface-treated with surface treatment agents such as organic silane coupling agents, titanate coupling agents, aluminate coupling agents, zirconate coupling agents, silicone compounds, higher fatty acids, fatty acid metal salts, and fatty acid esters to improve its dispersibility.

[0046] There are no restrictions on the consolidator used to bundle the fibrous filler, but for example, if the fibrous filler is an organic fiber, a polar resin or the like is preferably used.

[0047] Examples of polar resins include thermosetting resins such as unsaturated polyesters, vinyl ester resins, epoxy resins, phenol (e.g., resol type) resins, urea-melamine resins, polyimides, urethane resins, copolymers and modified versions thereof; and thermoplastic resins such as saturated polyesters, polyamides, acrylic resins, copolymers and modified versions thereof, and acid-modified polyolefins.

[0048] [Thermoplastic resin] Examples of thermoplastic resins include polycarbonate, polybutylene terephthalate, polyethylene terephthalate, polyethylene naphthalate, various polyamides (PA6, PA66, PA46, PA12, semi-aromatic PA, etc.), acrylonitrile-butadiene-styrene (ABS) resin, acrylonitrile-styrene (AS) resin, methyl methacrylate-styrene (MS) resin, polyethylene, polypropylene, polyacetal, polyamide-imide, polyethersulfone, polyimide, polyphenylene oxide, polyphenylene sulfide (PPS resin), polyphenylsulfone, polyetheretherketone, polystyrene, syndiotactic polystyrene, liquid crystalline polyester (liquid crystal polymer), thermoplastic polyurethane, polyvinyl chloride, fluororesin, and other thermoplastic resins, as well as mixtures thereof. These may be used individually or in combination of two or more. Thermoplastic resins can be appropriately selected and used based on the required properties such as heat resistance, chemical resistance, and moldability depending on the intended use.

[0049] The thermoplastic resin preferably contains at least one selected from the group consisting of polypropylene, polyester, polyamide, polycarbonate, polystyrene, polyphenylene ether, ABS resin, AS resin, PPS resin, and liquid crystal polymer.

[0050] [Resin composition] The resin composition obtained by the manufacturing method of the resin composition according to this embodiment (fibrous filler-reinforced thermoplastic resin composition) retains the inherent properties of a thermoplastic resin composition while improving mechanical strength due to the fibrous filler. The resin composition is thought to have long fiber lengths and excellent mechanical strength, such as flexural modulus. The resin composition can be used in various molding methods such as injection molding, extrusion molding, compression molding, blow molding, and injection compression molding. In particular, it can be suitably used in injection molding. The resin composition is suitably used, for example, in plastic parts that require mechanical strength. The resin composition is particularly suitable for automotive parts, building materials, and electrical product components. [Examples]

[0051] The present invention will be described below with reference to examples. The present invention is not limited to these examples.

[0052] Example 1 A thermoplastic resin composition consisting of 70% by weight of AS resin and 30% by weight of glass fibers was extruded to obtain a thermoplastic resin composition. A kneader having a roving weight control mechanism as shown in Figure 2 was used for extrusion. In the thermoplastic resin composition, the glass fibers were sufficiently dispersed in the thermoplastic resin. [Industrial applicability]

[0053] By using the kneader of the present invention, a thermoplastic resin composition containing a thermoplastic resin and a fibrous filler can be obtained from a thermoplastic resin composition containing a thermoplastic resin and a fibrous filler, in which the fibrous filler is sufficiently dispersed and which has excellent physical properties such as mechanical strength, as well as a molded product. The thermoplastic resin composition containing the fibrous filler can be used as a raw material for automotive parts, electrical and electronic product parts, and the like. [Explanation of symbols]

[0054] 100, 200, 300, 400 kneaders 112, 212, 312, 412 Cylinders (Mixing machine body) 114, 214, 414 Fiber supply ports 116, 216, 416 Resin supply ports 118, 218, 318, 418 screws 120, 220, 320, 420 roving devices 122, 222, 223, 322, 422 roving 124, 224, 324, 424 weighbridge 126, 226, 326, 426 fiber bundles 130, 230, 330, 430 Resin supply device 452, 454 tube

Claims

1. A kneader that controls the screw rotation speed by changing the weight of the roving.

2. The kneader according to claim 1, wherein the weight change of the roving is measured by a loss-in-weight formula, and the supply of roving fiber bundles and thermoplastic resin is controlled accordingly.

3. The kneader according to claim 1, wherein the amount of roving fiber bundles supplied to the kneader is controlled by a change in the weight of the roving.

4. The kneader according to claim 1, wherein the weight of the fiber bundles lost from the roving as they are fed out by the roving device is measured by a measuring instrument, and the progression of the decrease in this weight is compared with a preset target value of the fed-out weight (feed-out sequence), and the rotational speed of the roving and / or the kneader, which are the manipulated variables, are increased or decreased in the direction of reducing the deviation between the two, thereby increasing or decreasing the weight of the fiber bundles fed out by the roving device.

5. The kneader according to claim 1, further comprising a pulley or tube for supporting the fiber bundles of roving.

6. The kneader according to claim 1, wherein the fiber bundle is fed out from beneath the roving.

7. A kneading method comprising controlling the screw rotation speed of a kneader by changing the weight of the roving.

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