JP2007254566A - Filament pellet, method for producing the same, and method for producing fiber-reinforced thermoplastic resin composite material molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a filament pellet which can be injection-molded without causing constituent reinforcing fibers to shorten in length, can be stably fed into an injection molding machine without forming a bridge inside the hopper of the machine, and can give a molding having high strengths and high rigidity. <P>SOLUTION: The filament pellet 2 is a filament pellet prepared by folding and bundling at least one 200 μm-thick or thinner thermoplastic-resin-impregnated reinforced fiber tape along the direction of orientation of the reinforcing fibers, wherein the total number of the monofilaments constituting each reinforcing fiber is 1,000 to 80,000, the length of the pellet is 1 to 50 mm, and a fusion-bonded band formed by melting the thermoplastic resin being the impregnant of the thermoplastic-resin-impregnated reinforced fiber tape is formed around the circumference rectangularly crossing the direction of orientation of the thermoplastic-resin-impregnated reinforced fiber tape. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a long fiber pellet formed by forming a resin-containing long fiber tape into a predetermined shape, a method for producing the long fiber pellet, and a method for producing a fiber-reinforced thermoplastic resin composite material molded article using the long fiber pellet as a material.

  Fiber reinforced resin composite material reinforced with carbon fiber and other reinforced fibers has high tensile strength and tensile modulus, excellent heat resistance, chemical resistance, fatigue properties, and wear resistance, low coefficient of linear expansion, and dimensional stability. It has excellent features such as excellent electromagnetic shielding properties and excellent X-ray transparency, and is therefore widely applied to sports / leisure, aviation / space, and general industrial applications. Conventionally, a thermosetting resin such as an epoxy resin is often used as a matrix of a composite material, but recently, a thermoplastic resin has attracted attention from the viewpoint of recyclability and high-speed moldability.

  As a matrix of fiber reinforced thermoplastic resin composite material, acrylonitrile-butadiene-styrene copolymer (ABS), polyamide (nylon 6, nylon 66, etc.), polyacetal, polycarbonate, polypropylene, high density polyethylene, polyethylene terephthalate, polybutylene terephthalate , Polyetherimide, polystyrene, polyethersulfone, polyphenylene sulfide, polyetherketone, polyetheretherketone and the like.

  Examples of the molding method of the fiber reinforced thermoplastic resin composite material include injection molding of compound pellets, injection molding of long fiber pellets, injection compression molding, extrusion molding, and stamping molding using a random mat.

  Of these, injection molding using long fiber pellets as a material can easily form complex shapes, and does not require post-processing such as deburring. ing. In addition, a long fiber pellet can be manufactured by the method disclosed by patent document 1, for example.

  However, a molded product molded by the injection molding method using the long fiber pellets as a material is inferior in mechanical properties to a molded product molded by the press molding method.

  This is because, in the injection molding method, the reinforcing fibers in the long fiber pellet are broken and shortened between the time when the long fiber pellet as the material is introduced and the time of molding.

  In the press molding method, for example, when a fiber reinforced thermoplastic resin composite material is molded using a long fiber pellet made of resin-containing carbon fiber having a fiber length of 10 mm as a material, the length of the carbon fiber extracted from the molded product is about 10 mm. It is not shortened. On the other hand, in the injection molding method, when a fiber reinforced thermoplastic resin composite material is molded using a long fiber pellet made of resin-containing carbon fiber having the same fiber length of 10 mm as a material, the length of the carbon fiber extracted from the molded product is It may be as short as 1 mm.

Therefore, it is desired to lengthen the reinforcing fibers in the molded product of fiber reinforced thermoplastic resin composite material molded by the injection molding method and to improve the physical properties of the molded product.
JP 2003-305777 A (Claims)

  With respect to the above problems, efforts have been made mainly by injection molding machine manufacturers to reduce the compression ratio of the screw of the extruder of the injection molding machine or increase the clearance of the check ring. In addition, efforts are being made to devise gate shapes that make it difficult for reinforcing fibers to break, mainly by mold manufacturers. All of these are effective to some extent for increasing the length of the reinforcing fiber in the injection-molded product, but are still insufficient.

  The present inventor has been studying long fiber pellets as raw materials for manufacturing fiber reinforced thermoplastic resin composite material molded articles, and has come up with long fiber pellets formed by bundling wide and thin fiber reinforced thermoplastic tapes. did.

  This long fiber pellet is excellent in flexibility, so when it is used as a material, a fiber reinforced thermoplastic resin composite material is injection molded. In the extruder cylinder of the injection molding machine, it is reinforced even before the matrix resin melts. It has been found that the fiber can be prevented from breaking and that the fiber length in this part can be kept long.

  However, there is a case where the tapes support each other inside the raw material supply hopper of the injection molding machine to generate a bridge that hinders the falling of the tape. Therefore, the tape is folded along the fiber axis so as not to cause bridging, and the outer peripheral part is lightly welded, or after the tape is cut along the fiber axis until at least 3000 filaments or less, The present inventor has found that the occurrence of the bridge can be prevented by bundling the ridges in a circular cross section so as to bind the ridges and lightly welding the outer peripheral portion thereof.

  By adopting the above configuration, the fiber length of the reinforcing fiber during molding can be kept long, and the pellets support each other inside the long fiber pellet supply hopper of the injection molding machine to prevent the pellet from falling. It has been found that long fiber pellets are stably supplied from the hopper to the extrusion screw and further shortening in the screw is suppressed, and the resulting molded product has high strength and high strength. The inventor has learned that it is rigid and has completed the present invention.

  Accordingly, an object of the present invention is to provide a long fiber pellet that solves the above problems, a method for producing the same, and a method for producing a fiber-reinforced thermoplastic resin composite material using the long fiber pellets. .

  The present invention for achieving the above object is as follows.

  [1] A long fiber pellet in which one or more thermoplastic resin-impregnated reinforcing fiber tapes having a thickness of 200 μm or less are bent and bundled along the orientation direction of reinforcing fibers, and the total of single fibers constituting the reinforcing fibers is 1000 to 80000 long fiber pellets having a length of 1 to 50 mm.

  [2] The fusion band formed by melting a thermoplastic resin impregnated in the thermoplastic resin-impregnated reinforcing fiber tape is formed on the outer periphery perpendicular to the orientation direction of the thermoplastic resin-impregnated reinforcing fiber tape. Long fiber pellets.

  [3] The long fiber pellet according to [1], wherein the number of the thermoplastic resin-impregnated reinforcing fiber tape contained in the long fiber pellet is one, and the number of single fibers contained in the one tape is 12,000 or more.

  [4] The long fiber pellet according to [1], wherein two or more thermoplastic resin-impregnated reinforcing fiber tapes are contained in the long fiber pellet, and the number of single fibers contained in one tape is 3000 or less.

  [5] The long fiber pellet according to [1], wherein the reinforcing fiber is carbon fiber or glass fiber.

  [6] The long fiber pellet according to [1], wherein the thermoplastic resin is polypropylene, polyamide, or polycarbonate.

  [7] The long fiber pellet according to [1], wherein the mass content of reinforcing fibers in the long fiber pellet is 5 to 70%.

[8] A first step of impregnating a strand composed of 12,000 or more single fibers for reinforcing fibers with a thermoplastic resin to obtain a thermoplastic resin-impregnated reinforcing fiber tape having a width of 10 mm or more and a thickness of 200 μm or less;
A second step of irregularly bending the thermoplastic resin-impregnated reinforcing fiber tape along the orientation direction of the reinforcing fiber to obtain a bent tape;
A fusion bond having a fusion band formed of a thermoplastic resin melted on at least a part of the outer periphery of the bent tape by heating the outer periphery perpendicular to the orientation direction of the bent tape to the melting point of the thermoplastic resin or higher. A third step of obtaining a tape;
A fourth step of producing a long fiber pellet having a length of 1 to 50 mm by cutting the fusion tape perpendicularly to the orientation direction of the reinforcing fiber,
A method for producing long fiber pellets.

[9] a first step of obtaining a thermoplastic resin-impregnated reinforcing fiber tape having a width of 10 mm or more and a thickness of 200 μm or less by impregnating a strand composed of 12,000 or more single fibers for reinforcing fibers with a thermoplastic resin; ,
A second step of cutting the thermoplastic resin-impregnated reinforcing fiber tape along the orientation direction of the reinforcing fibers to obtain a split tape consisting of 3000 or less reinforcing fiber single fibers;
Aligning the plurality of divided tapes in the orientation direction of the reinforcing fibers and bundling them to obtain a divided tape bundle;
A fusion bond having a fusion band formed of a thermoplastic resin melted on at least a part of the outer periphery of the divided tape bundle by heating the outer circumference perpendicular to the orientation direction of the divided tape bundle to a melting point or higher of the thermoplastic resin. A fourth step of obtaining a tape bundle;
The fusion tape bundle comprises a fifth step of producing a long fiber pellet having a length of 1 to 50 mm by cutting perpendicularly to the orientation direction of the reinforcing fiber.
A method for producing long fiber pellets.

  [10] A method for producing a fiber-reinforced thermoplastic resin composite material molded article, wherein the long fiber pellet according to [1] is supplied to an injection molding machine and injected into an injection mold.

  Since the long fiber pellet of the present invention has the above-described configuration, when the fiber reinforced thermoplastic resin composite material is injection molded using this as a material, it is easily decomposed when kneaded with the screw of an injection molding machine. Being more flexible. As a result, the reinforcing fiber during molding becomes difficult to break and the fiber length can be kept long. Further, no bridge is generated inside the long fiber pellet supply hopper of the injection molding machine, and the long fiber pellet is stably supplied to the screw. For this reason, the obtained fiber reinforced thermoplastic resin composite material molded article has high strength and high rigidity.

  Hereinafter, the present invention will be described in detail.

  FIG. 1 shows an example of the concept of the long fiber pellet of the present invention, in which (A) is a side view and (B) is a sectional view.

  In FIG. 1, 2 is a long fiber pellet and 4 is a thermoplastic resin impregnated reinforcing fiber tape (reinforcing tape). This reinforcing tape 4 is in the form of a thin tape in which a reinforcing raw material fiber 6 unidirectionally oriented is impregnated with a thermoplastic resin 8, and the long fiber pellet 2 has one or more reinforcing tapes 4 [in FIG. Is one sheet], which is bent along the orientation direction of the reinforcing fibers 6 and bundled.

  The total number of single fibers constituting the reinforcing fibers 6 is 1000 to 80000, preferably 10,000 to 70000.

  The length (length in the fiber orientation direction) l of the long fiber pellet 2 is 1 to 50 mm, preferably 5 to 20 mm.

  When the length of the long fiber pellet 2 exceeds 50 mm, a bridge is generated inside the hopper at the time of injection molding, which hinders stable supply as a material of the long fiber pellet, which is not preferable. On the other hand, when the length of the long fiber pellet 2 is less than 1 mm, the fiber length of the reinforcing fiber in the molded product of the fiber reinforced thermoplastic resin composite material is shortened, which is not preferable.

  The thickness of the reinforcing tape 4 is 200 μm or less, preferably 100 μm or less.

  When the thickness of the reinforcing tape 4 exceeds 200 μm, the fibers are easily broken when injection molding is performed using the long fiber pellets made of this tape as a material, and the reinforcement in the resulting fiber reinforced thermoplastic resin composite material molded product This is not preferable because the fiber length of the fiber is shortened and the physical properties of the molded product are lowered.

  On the outer periphery in a direction perpendicular to the fiber orientation direction of the reinforcing tape 4, there are a plurality of fusion bands 10 formed by heating and melting the reinforcing tape 4 [two rows in FIG. In (B), two] are formed.

  In this example, the reinforcing fiber 4 included in the long fiber pellet 2 is one, and the number of single fibers included in one reinforcing tape is 12,000. The reinforcing tape 4 is irregularly bent along the fiber orientation direction (the length direction of the tape).

  The reinforcing fiber 6 constituting the reinforcing tape 4 is preferably carbon fiber, glass fiber, rose-based aramid fiber or the like. Among these fibers, the long fiber pellet of the present invention is particularly effective for carbon fibers that are easily broken by the conventional injection molding method from the viewpoint of the fiber length retention effect of the reinforcing fiber during injection molding.

  Examples of the thermoplastic resin 8 impregnated in the bending tape 4 include acrylonitrile-butadiene-styrene copolymer (ABS), polyamide (nylon 6, nylon 66, etc.), polyacetal, polycarbonate, polypropylene, high density polyethylene, polyethylene terephthalate, Polybutylene terephthalate, polyetherimide, polystyrene, polyethersulfone, polyphenylene sulfide, polyetherketone, polyetheretherketone and the like can be used.

  The impregnation amount of the thermoplastic resin in the bending tape 4 is preferably 30 to 95% by mass, that is, the content of reinforcing fibers in the bending tape 4 is preferably 70 to 5% by mass.

  As long as the physical properties of the long-fiber pellets of the present invention are within the above range, the production method and production apparatus are not particularly limited, but can be produced by, for example, the following production method and production apparatus. .

  FIG. 2 is a cross-sectional view showing another example of the concept of the long fiber pellet of the present invention.

  In FIG. 2, 12 is a long fiber pellet, and 14 is a thermoplastic resin-impregnated reinforcing fiber tape (reinforcing tape). The reinforcing tape 14 is a thin tape-like material in which a reinforcing raw material fiber 16 unidirectionally oriented is impregnated with a thermoplastic resin 18 and includes 3000 or less, preferably 100 to 2000 single fibers.

  A plurality of reinforcing tapes 14 (9 sheets in FIG. 2) are bundled to form a reinforcing tape bundle. On the outer periphery in the direction perpendicular to the fiber orientation direction of the reinforcing tape bundle, a plurality of rows and three [three in FIG. 2] of the fusion bands 20 formed by heating the reinforcing tape bundle are formed.

  The reinforcing tape 14 constituting the long fiber pellet 12 is preferable as the number of sheets increases so that the tape becomes more flexible. However, since the labor of cutting is difficult, it depends on the number of bundles of reinforcing fibers, but preferably two or more, More preferably, it is 4-40 sheets, Most preferably, it is 6-25 sheets.

  The example of FIG. 2 is the same as the example of FIG. 1 with respect to the thickness of the reinforcing tape, the material of the reinforcing fiber, the type of the thermoplastic resin, the mass content of the reinforcing fiber in the long fiber pellet, and the like.

  Hereinafter, the manufacturing method of the present long fiber pellet will be described in detail with reference to the drawings. An example of this production method (long fiber pellet production example A) is a method for producing the long fiber pellets of the example of FIG. 1 described above, and includes the first to fourth steps as follows.

(Long fiber pellet production example A first step)
FIG. 3 is a schematic view showing an example of an apparatus used for producing a thermoplastic resin-impregnated reinforcing fiber tape as a raw material for producing long fiber pellets of the present invention, (A) is a front view of the production apparatus, B) is a right side cross-sectional view along line AA in (A).

  In FIG. 3, 22 is an apparatus for manufacturing a thermoplastic resin-impregnated reinforcing fiber tape.

  Reference numeral 26 denotes a substantially rectangular parallelepiped molten resin impregnation apparatus, which includes a bowl-shaped upper mold part 34 whose lower surface is opened and a bowl-shaped lower mold part 38 whose upper surface is opened, and the upper mold part 34 and the lower mold part 38. Are fitted to each other to form a space portion 36 therein. The downstream end portion of the resin impregnation apparatus lower mold portion 38 is formed of members (sliding members) P and Q made of a sliding material chamfered in a substantially circular arc shape.

  A nozzle upper member 40 made of a roller is attached to the sliding members P and Q, and is attached to the U-shaped upper support frame 42 while being liquid-tightly pressed against the sliding members P and Q, and is fixed by an insertion bar 44. Has been. At the downstream end of the lower part 38 of the resin impregnation apparatus, a lower nozzle member 46 made of a roller, like the upper part 34, is pressed against the sliding members P and Q in a liquid-tight manner, and the lower support frame 48a. , 48b and fixed by the insertion bar 50.

  The resin impregnating apparatus lower mold part 38 is in contact with the nozzle upper member 40 and the nozzle lower member 46, and the sliding members P and Q on the resin impregnating apparatus lower mold part 38 side are also in contact with the nozzle upper member 40 side contact surface. The contact surface on the nozzle lower member 46 side has the same shape. Moreover, the sliding members P and Q of the lower part 38 of the resin impregnating apparatus are made of a material having moderate strength and flexibility such as gun metal. Therefore, the contact surface of the resin impregnating apparatus lower mold portion 38 with the nozzle upper member 40 and the nozzle lower member 46 has a structure in which the molten resin does not leak.

  The downstream slit nozzle 32 is formed by a gap between the nozzle upper member 40 and the nozzle lower member 46 between the sliding members P and Q. The length (slit width) between the sliding members P and Q is 10 mm or more, preferably 20 mm or more, and the gap (slit gap) between the nozzle upper member and the nozzle lower member is 500 μm or less, preferably 100 μm or less.

  The nozzle upper member 40 and the nozzle lower member 46 are both heated. The heating temperature is preferably in the vicinity of the melting point of the resin from the temperature in the molten resin impregnation apparatus 26. This temperature is usually controlled in the range of 100 to 400 ° C, preferably 150 to 300 ° C.

  Furthermore, in this example, the nozzle upper member 40 is formed to swing up and down, but the nozzle lower member 46 may swing up and down.

  In the manufacturing apparatus 22, the carbon fibers 24 are supplied to the resin impregnation apparatus space 36 from the upstream slit nozzle 30 in the form of a strand composed of 12,000 or more, preferably 12000 to 50000 single fibers. The carbon fiber strands 24 running in the resin impregnation device space 36 are pressed by the squeezing bars 64a and 64b and defibrated while running zigzag and are impregnated with a molten thermoplastic resin. The carbon fiber 24 impregnated with the molten thermoplastic resin is passed through the downstream slit nozzle 32 and drawn out in the form of a wide thin tape.

  The gap between one lower end 58a of the upper support frame 42 and the upper end 60a of the lower support frame 48a and the gap between the other lower end 58b of the upper support frame 42 and the upper end 60b of the lower support frame 48b are both slits on the downstream side. The gap is the same as that of the nozzle 32.

  In a normal operation, the gap between one lower end 58a of the upper support frame 42 and the upper end 60a of the lower support frame 48a and the other lower end of the upper support frame 42 so that the gap between the downstream slit nozzles 32 is constant. Gap adjustment members 62a and 62b, such as shim tape, are sandwiched between the gaps 58b and the upper end 60b of the lower support frame 48b. The gap between the downstream slit nozzles 32 can be adjusted by changing the thicknesses of the gap adjusting members 62a and 62b.

  In addition, 64a is a predetermined number (five in this figure) of upper iron bars (fixed) attached to the upper mold part 34, and 64b is a predetermined number (five in this figure) of lower iron bars attached to the lower mold part 38. (Fixed). In FIG. 2, an arrow X indicates the traveling direction of the carbon fiber strand 24, and 28 is a resin supply path for supplying a molten thermoplastic resin.

  In the manufacturing apparatus 22 in the example of FIG. 2, cooling rollers 74 and 76 having a temperature of about 20 ° C. are provided immediately downstream of the downstream slit nozzle 32. When a tape is manufactured using the manufacturing apparatus 22, the tape drawn from the downstream slit nozzle 32 is at a temperature higher than the melting point, so that the natural thickness cooling in the outside air causes surface tension and the like to increase the tape thickness. However, it is easy to deform in the direction in which the tape width decreases.

  Therefore, by providing the cooling rollers 74 and 76 immediately after the downstream slit nozzle 32, the tape can be instantly cooled to below the melting point of the matrix resin to prevent the tape deformation.

  The cooling rollers 74 and 76 are preferably attached as close as possible to the downstream side of the slit nozzle 32 on the downstream side.

  The cooling roller 74 is attached to the support frame 78 and is fixed by an insertion bar (rotating shaft) 80. The cooling roller 74 is attached to support frames 82 a and 82 b (not shown), and is fixed by an insertion bar (rotating shaft) 84.

  Support frames 82a and 82b (not shown) are connected and fixed at fixed ends 86a and 86b (not shown). On the other hand, the support frame 78 is separated from the support frames 82a and 82b (not shown), and is not connected to the fixed end. The cooling roller 74 is provided with a pressure cylinder 88 via an insertion bar 84 and a support frame 78.

  According to the above method, the thermoplastic fiber-impregnated reinforcing fiber comprising 12,000 or more reinforcing fibers oriented in parallel with each other, which is a raw material for producing the long fiber pellets of the present invention, having a tape width of 10 mm or more and a tape thickness of 200 μm or less. A tape (reinforced tape) is obtained.

  FIG. 4 is a sectional view showing the concept of an example of this reinforcing tape. In FIG. 4, 92 is a reinforced tape. This reinforcing tape 92 is a thin tape-like material in which a reinforcing fiber 94 oriented in one direction is impregnated with a thermoplastic resin 96.

(Long fiber pellet production example A 2nd step)
A bending tape is obtained by irregularly bending the reinforcing tape along the orientation direction of the reinforcing fibers.

(Long fiber pellet production example A third step)
The fusion tape having a fusion band formed of a thermoplastic resin melted on at least a part of the outer circumference of the bent tape by heating the outer circumference perpendicular to the orientation direction of the bent tape to the melting point of the thermoplastic resin or higher. Adhesive tape is obtained.

(Long fiber pellet production example A, 4th step)
A long fiber pellet having a length of 1 to 50 mm is obtained by cutting the above-mentioned fusion tape while adjusting the pellet length perpendicularly to the orientation direction of the reinforcing fibers.

  Next, another example of the method for producing long fiber pellets of the present invention (Long fiber pellet production example B) will be described. This manufacturing method is a method for manufacturing the long fiber pellet of the example of FIG. 2 described above, and includes the first to fifth steps as follows.

(First step of long fiber pellet production example B)
By the same method as the first step of the method for producing long fiber pellets in the example of FIG. 1 (long fiber pellet production example A), 12,000 or more parallel fibers that are raw materials for producing long fiber pellets of the present invention are parallel to each other. Thus, a thermoplastic resin-impregnated reinforcing fiber tape (reinforced tape) having a tape width of 10 mm or more and a tape thickness of 200 μm or less is obtained.

(Long fiber pellet production example B 2nd process)
By cutting the reinforcing tape in parallel with the orientation direction of the reinforcing fibers, a split tape made of single fibers of 3000 or less reinforcing fibers with a tape width of 3 mm or less is obtained.

(Long fiber pellet production example B 3rd process)
A split tape bundle is obtained by aligning and bundling two or more of the above split tapes, preferably 4 to 20 in the orientation direction of the reinforcing fibers.

(Long fiber pellet production example B, 4th step)
A melt formed of a thermoplastic resin melted on at least a part of the outer periphery of the folded tape bundle by heating a part or the whole of the outer periphery perpendicular to the orientation direction of the split tape bundle to a temperature equal to or higher than the melting point of the thermoplastic resin. A fusion tape bundle having a banding is obtained.

(Fifth process of long fiber pellet production example B)
A long fiber pellet having a length of 1 to 50 mm is obtained by cutting the above-mentioned fusion tape bundle while adjusting the pellet length perpendicularly to the orientation direction of the reinforcing fibers.

(Production example of fiber reinforced thermoplastic resin composite material molding)
The long fiber pellets obtained in the above long fiber pellet production example A, long fiber pellet production example B, etc. are heated to melt the thermoplastic resin, and the kneaded kneaded material is injected into an injection mold to be molded. Can keep the fiber length of the reinforcing fiber long, the bridge is not generated inside the long fiber pellet supply hopper of the injection molding machine, the long fiber pellet is stably supplied, and the obtained fiber reinforced thermoplastic resin The composite material molded product has high strength and high rigidity.

  As the injection molding machine, a known machine as shown in FIG. 5 can be used.

  In FIG. 5, reference numeral 102 denotes an injection molding machine, which includes a screw body 104 and a heating cylinder 106. In the screw body 104, flights 114a, 114b, 114c,..., 114k, 114l,..., 114r from the hopper 110 side (upstream side) to which the long fiber pellets 108 are supplied toward the mold 112 side (downstream side). 114s and 114t are formed, and screw grooves 116a, 116b, ..., 116k, ..., 116r, 116s are formed between the flights.

  A screw head 120 is formed on the downstream side of the screw main body 104 with a small diameter portion 118 interposed therebetween. A check ring 122 is formed in the heating cylinder 106 opposite the small diameter portion 118.

  The mold 112 includes a front mold 124 and a rear mold 126, and the kneaded mixture of long fiber pellets supplied from the gate 128 is introduced into the gap 130 between the front mold and the rear mold, and a molded product is obtained here.

  The long fiber pellets 108 supplied from the hopper 110 receive heat energy from the outside in the heating cylinder 106 and, along with the rotation of the screw body 104, the kneaded material obtained passes through the check ring 122 to the mold 112. It is sent.

  Due to this shear flow, the conventional long fiber pellets are easily broken, and the fiber length of the reinforcing fibers in the resulting fiber reinforced thermoplastic resin composite material is shortened, and the physical properties of the molded product are deteriorated.

  On the other hand, the long fiber pellet of the present invention can keep the fiber length of the reinforcing fiber during molding long even if it receives this shear flow. This is because when the thermoplastic resin-impregnated reinforcing fiber tape of the raw material for producing long fiber pellets of the present invention is impregnated with the thermoplastic resin, it is defibrated while being zigzag pressed against the ironing bar and defibrated by rapid cooling. It is considered that the state is maintained and the bundle of them is fused on the peripheral surface, but the inside is kept in a defibrated state, so that shear flow can be received flexibly.

  Reinforced tapes, long fiber pellets, and fiber reinforced thermoplastic resin composite material molded articles were produced under the conditions described in the following examples and comparative examples.

[Example 1]
In the manufacturing apparatus shown in FIG. 3, after adjusting the downstream slit nozzle gap to 130 μm and the stress between the upper and lower nozzle members to 30 N, the molten resin [polypropylene resin (general-purpose injection molding grade, melt flow rate 20 g / 10 min)] and the temperature of the upper and lower nozzle members were adjusted to 230 ° C.

  In this manufacturing apparatus, the cooling roller was installed at a location of 200 mm in the axial distance between the nozzle roller and the cooling roller downstream of the downstream slit nozzle, and the temperature of the cooling roller was adjusted to 20 ° C.

  In this molten resin impregnation apparatus, raw material carbon fiber strand [Besphite STS-24K F301 (diameter 7 μm × 24000 filament, fineness 1.6 g / m) manufactured by Toho Tenax Co., Ltd.] was run at 3 m / min to strengthen the thermoplastic resin impregnation. A fiber tape (reinforced tape) was prepared. The width of the obtained reinforcing tape was 30 mm, and the mass content of the carbon fiber was 30%.

  Next, the reinforcing tape was irregularly bent along the orientation direction of the carbon fibers to obtain a bent tape.

  A fusion tape having a fusion band formed of a thermoplastic resin melted on at least a part of the outer periphery of the bending tape by heating the outer periphery of the bending tape to 180 ° C. which is equal to or higher than the melting point of the thermoplastic resin. Obtained.

  This fusion tape was cut into a length of 10 mm perpendicular to the orientation direction of the reinforcing fibers to obtain long fiber pellets. Subsequently, this long fiber pellet was injection molded at 230 ° C. using an injection molding machine shown in FIG. 5 to produce a flat plate of 150 mm square × 3.1 mm thickness.

  In addition, the carbon fibers in the long fiber pellets during injection molding are (1) screw kneading compression (compression ratio of this screw: 2.96%), (2) check ring passing, (3) mold gate passing Where the carbon fiber breaks at the time was examined by measuring the weight average fiber length in the long fiber pellet 108, screw groove 116k, check ring 122, check ring 122, and molded product 130 of FIG. The results are shown in Table 1.

  The weight average fiber length was measured by the following method.

Hot concentrated sulfuric acid was added to 0.5 g of the collected sample to decompose the polypropylene resin of the matrix, and the carbon fiber was taken out. Next, carbon fiber was dispersed in water using an ultrasonic device, and the quadrant was repeated three or more times, followed by filtration. The fiber length of 500 or more carbon fibers remaining on the filter paper is measured, and the weight average fiber length is expressed by the following formula: weight average fiber length = Σ (fiber length) ² / Σ (fiber length)
Was determined using.

  For the 150 mm square × 3.1 mm thick flat plate, five bending test pieces of 10 mm width × 90 mm length × 3.1 mm thickness were cut out from the flat plate, and a three-point bending test (span / thickness ratio) in accordance with JIS K 7171. = 20, test speed 5 mm / min), and bending strength was measured. The results are shown in Table 1.

[Example 2]
The reinforcing tape obtained in Example 1 was cut in parallel with the orientation direction of the carbon fibers to obtain a split tape having a tape width of 1.3 mm and consisting of about 1000 carbon fibers.

  The 24 divided tapes are bundled to obtain a divided tape bundle, and the outer periphery of the divided tape bundle is heated to 180 ° C., which is equal to or higher than the melting point of the thermoplastic resin, to melt at least a part of the outer periphery of the divided tape bundle. A fusion tape bundle having a fusion zone formed of resin was obtained.

  This fusion tape bundle was cut into a length of 10 mm perpendicular to the orientation direction of the reinforcing fibers to obtain long fiber pellets. Subsequently, a molded product was produced for the long fiber pellets using the injection molding machine shown in FIG. 5 in the same manner as in Example 1. The change in the weight average fiber length of the reinforcing fibers during the injection molding, and the injection molded product The bending strength was measured. The results are shown in Table 1.

[Comparative Example 1]
In the reinforcing tape manufacturing apparatus shown in FIG. 3, the downstream slit nozzle 32 was replaced with a die having a circular opening and a diameter of 2.5 mm, and the cooling rollers 74 and 76 were removed. Using this remodeling device, except for the downstream side of the die, the same operation as in Example 1 was performed to produce a thermoplastic resin-impregnated reinforced fiber molded product (reinforced molded product). Was circular and had a rod shape with a diameter of 2.5 mm.

  This rod-like reinforced molded product was cut into a length of 10 mm perpendicular to the orientation direction of the reinforcing fibers to obtain long fiber pellets. FIG. 6 is a cross-sectional view showing the concept of the obtained long fiber pellets. In FIG. 6, 132 is a long fiber pellet. This long fiber pellet 132 is formed by impregnating a reinforcing fiber 134 oriented in one direction with a thermoplastic resin 136.

  In addition, the reinforced molded product of Comparative Example 1 was produced through a round die while the resin was still melted after impregnating the molten resin into the expanded reinforcing fiber strand in the same manner as in Example 1. Is. Therefore, the thermoplastic fiber 136 is sufficiently impregnated in the expanded reinforcing fiber strand 134 as shown in FIG.

  Subsequently, a molded product was produced for the long fiber pellets using the injection molding machine shown in FIG. 5 in the same manner as in Example 1. The change in the weight average fiber length of the reinforcing fibers during the injection molding, and the injection molded product The bending strength was measured. The results are shown in Table 1.

[Comparative Example 2]
In the reinforced molded product manufacturing apparatus of Comparative Example 1, the ironing bars 64a and 64b were removed. Using this remodeling device, except for the operation with the molten resin impregnation device 26, the same operation as in Comparative Example 1 was performed to produce a reinforced molded product. The resulting reinforced molded product had a circular cross section and a diameter of It was a 2.5 mm rod.

  This rod-like reinforced molded product was cut into a length of 10 mm perpendicular to the orientation direction of the reinforcing fibers to obtain long fiber pellets. FIG. 7 is a cross-sectional view showing the concept of the obtained long fiber pellets. In FIG. 7, 142 is a long fiber pellet. The long fiber pellet 142 is formed by impregnating a reinforcing fiber 144 oriented in one direction with a thermoplastic resin 146.

  In addition, the reinforcement molding of the comparative example 2 was produced through the round die in the same state as in Example 1 without impregnating the reinforcing fiber strand without sufficiently spreading the molten resin. Therefore, as shown in FIG. 7, the reinforcing fiber strand 144 is not sufficiently impregnated with the thermoplastic resin 146.

  Subsequently, a molded product was produced for the long fiber pellets using the injection molding machine shown in FIG. 5 in the same manner as in Example 1. The change in the weight average fiber length of the reinforcing fibers during the injection molding, and the injection molded product The bending strength was measured. The results are shown in Table 1.

[Comparative Example 3]
The reinforcing tape obtained in Example 1 was cut into a length of 10 mm perpendicular to the orientation direction of the reinforcing fibers, and was put into the injection molding machine shown in FIG. However, a bridge occurred inside the hopper 110, and a test piece molded product could not be obtained.

  In the reinforcing tapes of Examples 1 and 2, since the reinforcing bar spread by the heating bar and the ironing bar inside the resin impregnation apparatus is immediately cooled and solidified, a wide flat shape can be produced, and this tape is sheared. When the long fiber pellets obtained by bundling and fusing are injection molded using the material, the fiber length of the reinforcing fiber during molding can be kept long, and the resulting carbon fiber reinforced thermoplastic resin (CFRTP) molded product Showed high bending strength.

  The thermoplastic resin-impregnated reinforced fiber molded product (reinforced molded product) obtained in Comparative Examples 1 and 2 is a rod-shaped product having a circular cross section, and the long fiber pellets obtained by cutting this were injection molded using the material. However, the reinforcing fiber was easily broken during molding, and the obtained CFRTP molded product did not show very high bending strength.

An example of the concept of this invention long fiber pellet is shown, (A) is a side view, (B) is sectional drawing. It is sectional drawing which shows the other example of the concept of this invention long fiber pellet. It is the schematic which shows an example of the manufacturing apparatus of the thermoplastic resin impregnation reinforcement | strengthening fiber tape which is a raw material for long fiber pellet manufacture of this invention, (A) is a front view of the said manufacturing apparatus, (B) is (A). It is right side sectional drawing along the AA line in FIG. It is sectional drawing which shows the concept of an example of the thermoplastic resin impregnation reinforcement | strengthening fiber tape used as a raw material of this invention long fiber pellet. It is an outline side sectional view showing the injection molding machine used in Examples 1-2 and comparative examples 1-3. It is sectional drawing which shows the concept of the long fiber pellet obtained by the comparative example 1. FIG. It is sectional drawing which shows the concept of the long fiber pellet obtained by the comparative example 2.

Explanation of symbols

2, 108, 132, 142 Long fiber pellets 4, 14, 92 Reinforcing tape 6, 16, 94, 134, 144 Reinforcing fibers 8, 18, 96, 136, 146 Thermoplastic resin 10, 20 Fusion zone 22 Thermoplastic resin Manufacturing apparatus for impregnated reinforcing fiber tape 24 Reinforcing fiber 26 Molten resin impregnating apparatus 28 Resin supply path for supplying molten thermoplastic resin 30 Upstream slit nozzle 32 Downstream slit nozzle 34 Molten resin impregnating apparatus upper mold part 36 Melting resin impregnating apparatus space Part 38 Molten resin impregnation apparatus lower mold part 40 Nozzle upper member 42, 48a, 48b, 78, 82a Support frame 44, 50, 80, 84 Insertion bar 46 Nozzle lower member 52a, 52b, 86a Fixed end 56, 88 Energizing means 58a, 58b Lower end of support frame 60a, 60b Upper end of support frame 62a, 62b Gap adjusting means 6 4a, 64b Ironing bar 74, 76 Cooling roller 102 Injection molding machine 104 Screw body 106 Heating cylinder 110 Hopper 112 Mold 114a, 114b, 114c, ..., 114k, 114l, ..., 114r, 114s, 114t Flight 116a, 116b, ... , 116k,..., 116r, 116s Screw groove 118 Small diameter portion 120 Screw head 122 Check ring 124 Mold front mold 126 Mold rear mold 128 Gate 130 Gap between front mold and rear mold l Length of long fiber pellet m Long fiber pellet width P, Q Slide member X Arrow indicating the running direction of the carbon fiber strand

Claims (10)

A long fiber pellet in which one or more thermoplastic resin-impregnated reinforcing fiber tapes having a thickness of 200 μm or less are bent and bundled along the orientation direction of the reinforcing fibers, and the total of the single fibers constituting the reinforcing fibers is 1000 to 80000 A long fiber pellet having a length of 1 to 50 mm. The long fiber pellet according to claim 1, further comprising a fusion band formed by melting a thermoplastic resin impregnated in the thermoplastic resin-impregnated reinforcing fiber tape on an outer periphery perpendicular to an orientation direction of the thermoplastic resin-impregnated reinforcing fiber tape. . The long fiber pellet according to claim 1, wherein the length of the thermoplastic resin-impregnated reinforcing fiber tape contained in the long fiber pellet is one, and the number of single fibers contained in the single tape is 12,000 or more. 2. The long fiber pellet according to claim 1, wherein two or more thermoplastic resin-impregnated reinforcing fiber tapes are contained in the long fiber pellet, and the number of single fibers contained in one tape is 3000 or less. The long fiber pellet according to claim 1, wherein the reinforcing fiber is carbon fiber or glass fiber. The long fiber pellet according to claim 1, wherein the thermoplastic resin is polypropylene, polyamide or polycarbonate. The long fiber pellet according to claim 1, wherein the mass content of the reinforcing fiber in the long fiber pellet is 5 to 70%. A first step of impregnating a strand composed of 12,000 or more single fibers for reinforcing fibers with a thermoplastic resin to obtain a thermoplastic resin-impregnated reinforcing fiber tape having a width of 10 mm or more and a thickness of 200 μm or less;
A second step of irregularly bending the thermoplastic resin-impregnated reinforcing fiber tape along the orientation direction of the reinforcing fiber to obtain a bent tape;
A fusion bond having a fusion band formed of a thermoplastic resin melted on at least a part of the outer periphery of the bent tape by heating the outer periphery perpendicular to the orientation direction of the bent tape to the melting point of the thermoplastic resin or higher. A third step of obtaining a tape;
A fourth step of producing a long fiber pellet having a length of 1 to 50 mm by cutting the fusion tape perpendicularly to the orientation direction of the reinforcing fiber,
A method for producing long fiber pellets. A first step of impregnating a strand composed of 12,000 or more single fibers for reinforcing fibers with a thermoplastic resin to obtain a thermoplastic resin-impregnated reinforcing fiber tape having a width of 10 mm or more and a thickness of 200 μm or less;
A second step of cutting the thermoplastic resin-impregnated reinforcing fiber tape along the orientation direction of the reinforcing fibers to obtain a split tape consisting of 3000 or less reinforcing fiber single fibers;
Aligning the plurality of divided tapes in the orientation direction of the reinforcing fibers and bundling them to obtain a divided tape bundle;
A fusion bond having a fusion band formed of a thermoplastic resin melted on at least a part of the outer periphery of the divided tape bundle by heating the outer circumference perpendicular to the orientation direction of the divided tape bundle to a melting point or higher of the thermoplastic resin. A fourth step of obtaining a tape bundle;
The fusion tape bundle comprises a fifth step of producing a long fiber pellet having a length of 1 to 50 mm by cutting perpendicularly to the orientation direction of the reinforcing fiber.
A method for producing long fiber pellets. A method for producing a fiber-reinforced thermoplastic composite material molded article, comprising feeding the long fiber pellet according to claim 1 to an injection molding machine and injecting the pellet into an injection mold.

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