JP5844967B2 - Fiber-reinforced thermoplastic resin molded article and method for producing the same - Google Patents

Description

  The present invention relates to a fiber-reinforced thermoplastic resin molded article and a method for producing the same.

In recent years, it has been studied to change the material of parts from metal to resin in various fields. Among them, in view of rigidity, impact resistance and the like, attempts have been made to employ a fiber reinforced resin reinforced with reinforcing fibers instead of metal.
The fiber reinforced resin includes a fiber reinforced thermoplastic resin in which a thermoplastic resin is used as a matrix resin. For example, in a vehicle field such as an automobile, it is applied to a frame material used around an engine or a bumper beam. (For example, refer to Patent Documents 1 to 4).

JP-A-5-9301 JP-A-6-313292 JP-A-7-88840 JP-A-9-216225

Thus, in manufacturing members of various shapes using the fiber reinforced thermoplastic resin, it may be necessary to manufacture a plurality of fiber reinforced thermoplastic resin molded products and then join them. .
However, fiber reinforced thermoplastic resin molded products may be difficult to join.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fiber-reinforced thermoplastic resin molded article in which the joint portion is sufficiently joined, and a method for producing the same.

The fiber reinforced thermoplastic resin molded article of the present invention is a fiber reinforced thermoplastic resin molded article in which a plurality of members are joined at joints, and each joint has an inner fiber reinforced resin layer including a joined surface; And an outer fiber reinforced resin layer provided outside the inner fiber reinforced resin layer, and the outer fiber reinforced resin layer is composed of at least one layer, and at least one of the reinforcing fibers is the inner fiber. The number average fiber length is longer than the reinforcing fiber of the reinforced resin layer.
It is preferable that the reinforcing fibers contained in the inner fiber reinforced resin layer are randomly distributed.
The fiber length of the reinforcing fibers contained in the inner fiber reinforced resin layer is preferably 5 to 100 mm in number average.
Among the outer fiber reinforced resin layers, the at least one layer of reinforcing fibers having a number average fiber length longer than that of the inner fiber reinforced resin layer is preferably a continuous fiber.
The continuous fiber is preferably a unidirectional material in which the continuous fibers are aligned in one direction or a cloth material in which the unidirectional material is woven.
The method for producing a fiber-reinforced thermoplastic resin molded article of the present invention is a method for producing a fiber-reinforced thermoplastic resin molded article in which a plurality of members are joined at joints, and each joint includes a surface to be joined. It consists of an inner fiber reinforced resin layer and an outer fiber reinforced resin layer provided outside the inner fiber reinforced resin layer, and the outer fiber reinforced resin layer is composed of at least one layer, and at least one of them is reinforced. The fibers have a number average fiber length longer than the reinforcing fibers of the inner fiber reinforced resin layer.
The joining is preferably performed by a vibration welding method.

  ADVANTAGE OF THE INVENTION According to this invention, the fiber reinforced thermoplastic resin molded product which the junction part fully joined can be provided.

It is a perspective view which shows an example of the fiber reinforced thermoplastic resin molded product of this invention. It is a longitudinal cross-sectional view of the fiber reinforced thermoplastic resin molded product of FIG. It is a perspective view which shows typically the random sheet used for the inner side fiber reinforced resin layer of the fiber reinforced thermoplastic resin molded product of FIG. It is a perspective view which shows an example of the metal mold | die used for shaping | molding of the fiber reinforced thermoplastic resin molded product of FIG. It is a perspective view which shows the member which comprises the fiber reinforced thermoplastic resin molded product of FIG. It is a perspective view which shows typically the lamination sheet used in Example 1. FIG. 4 is a perspective view schematically showing a prepreg laminated sheet used in Example 2. FIG.

Hereinafter, the present invention will be described in detail.
FIG. 1 is a perspective view showing an example of a fiber-reinforced thermoplastic resin molded product of the present invention, and FIG. 2 is a longitudinal sectional view of the fiber-reinforced thermoplastic resin molded product of FIG.
The fiber reinforced thermoplastic resin molded product 10 is a hollow molded product in which a first member 20 and a second member 30 made of a fiber reinforced thermoplastic resin molded product are joined at respective joints. The first member 20 and the second member 30 in this example have the same size and shape, and the concave portions 21 and 31 along the longitudinal direction and the constant width formed along the longitudinal direction on both sides thereof. Edge portions 22 and 32.
The first member 20 and the second member 30 are arranged so that the concave portions 21 and 31 and the edge portions 22 and 32 face each other, and then the surfaces of the opposite edge portions 22 and 32 (to-be-joined) Surface) 22a and 32a are joined together by vibration welding to form a hollow shape.

  As shown in FIG. 2, the first member 20 and the second member 30 are formed of a single layer including a unidirectional material (UD material) in which continuous reinforcing fibers (continuous fibers) are aligned in one direction as reinforcing fibers. It has a two-layer structure of outer fiber reinforced resin layers 23 and 33 and one layer of inner fiber reinforced resin layers 24 and 34 in which bundled short fibers are randomly distributed as reinforcing fibers. And the 1st member 20 and the 2nd member 30 are arrange | positioned so that the inner side fiber reinforced resin layers 24 and 34 side may be located inside, and the edge parts 22 and 32 are joined. Therefore, in each joint part of the first member 20 and the second member 30, the inner fiber reinforced resin layers 24 and 34 are located on the surfaces of the edge parts 22 and 32, that is, the parts including the joined surfaces 22a and 32a. The outer fiber reinforced resin layers 23 and 33 are located outside thereof.

Examples of the reinforcing fiber constituting the fiber reinforced thermoplastic resin include glass fiber, carbon fiber, and aramid fiber. For the outer fiber reinforced resin layers 23 and 33 and the inner fiber reinforced resin layers 24 and 34, the same type of reinforcing fiber is usually used, but different types of reinforcing fibers may be used depending on the purpose.
In this example, the unidirectional material used for the outer fiber reinforced resin layers 23 and 33 is obtained by opening a bundle of numerous reinforcing fiber filaments and arranging them. The outer fiber reinforced resin layers 23 and 33 are composed of a prepreg in which a unidirectional material is impregnated with a thermoplastic resin.
Further, in the inner fiber reinforced resin layers 24 and 34 in this example, bundled short fibers are randomly distributed in the layer. The inner fiber reinforced resin layers 24 and 34 are obtained by, for example, impregnating the above-mentioned unidirectional material with a thermoplastic resin, cutting the fiber into a fiber length of, for example, 5 to 100 mm, and randomly dispersing the short fibers. It is comprised from what is called the random sheet | seat 40 as shown in FIG. 3 obtained by heating, pressurizing, and cooling in a type | mold. In the figure, reference numeral 41 denotes dispersed short fibers.
Here, the random dispersion means a bundle of a large number of reinforcing fiber filaments, a state in which the reinforcing fibers are dispersed without having a specific direction, and a specific directionality as individual reinforcing fiber filaments. It includes any of the states that are distributed without being held.

The thermoplastic resin constituting the fiber reinforced thermoplastic resin is not particularly limited, polyolefin such as polyethylene and polypropylene, polyester such as polyethylene terephthalate and polybutylene terephthalate, polystyrene, ABS resin, acrylic resin, vinyl chloride, polyamide 6 and the like. Polyamide, polycarbonate, polyphenylene ether, polyether sulfone, polysulfone, polyether imide, polyketone, polyether ketone, polyether ether ketone and the like can be used. Moreover, the modified body of these each resin may be used, and multiple types of resin may be blended and used. Further, the thermoplastic resin may contain various additives, fillers, colorants and the like.
For the outer fiber reinforced resin layers 23 and 33 and the inner fiber reinforced resin layers 24 and 34, the same type of thermoplastic resin is usually used, but different types of thermoplastic resins may be used depending on the purpose.

  The volume content of reinforcing fibers in the inner fiber reinforced resin layers 24 and 34 (measured according to JIS K 7052) is preferably 10 to 60%. By setting the volume content of the reinforcing fibers to 60% or less, the first member 20 and the second member 30 are more favorably bonded at the bonded portion. If the volume content of the reinforcing fiber exceeds 60%, it may be difficult to bond, or even if bonded, the degree of bonding is insufficient, and may be peeled off after being bonded once. On the other hand, when the volume content of the reinforcing fibers is 10% or more, physical properties derived from the reinforcing fibers in the inner fiber reinforced resin layers 24 and 34 can be exhibited.

  It is preferable that the fiber length of the short fiber 41 contained in the inner fiber reinforced resin layers 24 and 34 is 5 to 100 mm in number average. If it is 5 mm or more, the physical property derived from the reinforced fiber which makes the short fiber 41 can be exhibited, and if it is 100 mm or less, the 1st member 20 and the 2nd member 30 can be favorably joined.

The volume content of reinforcing fibers in the outer fiber reinforced resin layers 23 and 33 is preferably 10 to 60%. When the volume content of the reinforcing fibers is 10% or more, physical properties derived from the reinforcing fibers in the outer fiber reinforced resin layers 23 and 33 can be exhibited. If the volume content of the reinforcing fibers exceeds 60%, the reinforcing fibers may not be sufficiently covered with the resin.
The thickness of the outer fiber reinforced resin layer 23 is 5 to 95% and the thickness of the inner fiber reinforced resin layer 24 is 95% of the total thickness of the outer fiber reinforced resin layer 23 and the inner fiber reinforced resin layer 24. It is preferable to set it to -5%. By setting the thickness of the outer fiber reinforced resin layer 23 to 5% or more, physical properties derived from the reinforced fiber layer can be exhibited. By setting the thickness of the inner fiber reinforced resin layer 24 to 5% or more, the bonded surface 22a of the first member 20 and the bonded surface 32a of the second member 30 can be bonded well. The total thickness of the outer fiber reinforced resin layer 23 and the inner fiber reinforced resin layer 24 is preferably 0.5 mm to 10 mm. By setting the total thickness of the outer fiber reinforced resin layer 23 and the inner fiber reinforced resin layer 24 to 0.5 mm or more, a molded product of a fiber reinforced thermoplastic resin having excellent physical properties can be provided. If the total thickness of the outer fiber reinforced resin layer 23 and the inner fiber reinforced resin layer 24 is 10 mm, it has sufficiently excellent physical properties.
Similarly, the thickness of the outer fiber reinforced resin layer 33 is 5 to 95% and the thickness of the inner fiber reinforced resin layer 34 is 100% of the total thickness of the outer fiber reinforced resin layer 33 and the inner fiber reinforced resin layer 34. It is preferably 95 to 5%. The reason for this is the same as described above. The total thickness of the outer fiber reinforced resin layer 33 and the inner fiber reinforced resin layer 34 is preferably 0.5 mm to 10 mm. The reason for this is the same as described above.

The fiber-reinforced thermoplastic resin molded article 10 as shown in FIG. 1 can be manufactured as follows, for example.
First, a prepreg for forming the outer fiber reinforced resin layers 23 and 33 is formed. Specifically, as a reinforcing fiber, a bundle-like continuous fiber composed of a large number of reinforcing fiber filaments is prepared, and after opening the fiber, the fiber bundle is impregnated with a thermoplastic resin to form a tape-like or sheet-like fiber. Get a one-way prepreg. Here, the thickness of the prepreg can be appropriately set according to the application, the intended physical properties, etc., but is in the range of 30 to 300 μm, for example. In FIG. 2, the outer fiber reinforced resin layers 23 and 33 are configured by one prepreg layer, but may be configured by stacking two or more layers. The thickness as the outer fiber reinforced resin layer is, for example, in the range of 30 μm to 5.0 mm.

  On the other hand, a random sheet 40 for forming the inner fiber reinforced resin layers 24 and 34 is formed. Specifically, the above-mentioned unidirectional prepreg is cut to a length of, for example, 5 to 100 mm, and is randomly dispersed in a pair of flat plate molds. Then, depending on the type of the thermoplastic resin impregnated, for example, the molding temperature is set to (resin melting point or glass transition temperature) ° C. to (resin melting point or glass transition temperature + 100) ° C., and molding pressure 0.2 to After heating and pressing under the conditions of 2.0 MPa and holding time of 1 to 30 minutes, the mold is cooled to obtain a random sheet 40 in which short fibers 41 are randomly dispersed. Here, the thickness of the random sheet 40 is, for example, in the range of 100 μm to 5.0 mm.

Next, the above-mentioned unidirectional prepreg and the random sheet 40 are laminated to form a laminated sheet, and this laminated sheet is preheated by heating means such as an infrared heater, and then an upper mold 51 and a lower mold as shown in FIG. It is placed in a molding die 50 made of 52. Depending on the type of impregnated thermoplastic resin, for example, the molding temperature is (resin melting point or glass transition temperature−100) ° C. to (resin melting point or glass transition temperature) ° C., and the molding pressure is 3.0. The molded product of FIG. 5 is obtained by cooling the molding die 50 after heating and pressing under the conditions of ˜30 MPa and a holding time of 0.5 to 10 minutes. This molded product is used as the first member 20 and the second member 30.
When the laminated sheet is placed in the molding die 50 of this example, the outer fiber reinforced resin layers 23 and 33 are positioned on the lower die 52 side.

  Next, the obtained first member 20 and second member 30 are arranged so that the concave portions 21 and 31 and the edges 22 and 32 face each other and form a hollow shape, and the facing edges 22 and 32 face each other. Are joined by the vibration welding method so that the surfaces (bonded surfaces) 22a and 32a are joined together. The vibration welding method is a method of joining by vibrating the bonded surfaces 22a and 32a in contact with each other, and can be performed by a commercially available vibration welding machine.

In such a method, the to-be-joined surfaces 22a and 32a of the joint part of the 1st member 20 and the 2nd member 30 are comprised by the inner side fiber reinforced resin layers 24 and 34, and reinforcement | strengthening of these inner side fiber reinforced resin layers 24 and 34 The fibers are short fibers in this example, the number average fiber length being shorter than the reinforcing fibers of the outer fiber reinforced resin layers 23 and 33. Therefore, when vibration is applied to the joint portion by the vibration welding method, the short fibers of the bonded surfaces 22a and 32a of the first member 20 and the short fibers of the bonded surfaces 22a and 32a of the second member 30 are good. As a result, the joined surfaces 22a and 32a are favorably joined.
On the other hand, outer fiber reinforced resin layers 23 and 33 are disposed outside the inner fiber reinforced resin layers 24 and 34, and the reinforced fibers of the outer fiber reinforced resin layers 23 and 33 are connected to the inner fiber reinforced resin layers 24 and 34. In this example, it is a unidirectional material having a number average fiber length longer than that of the reinforcing fiber to be formed. Therefore, the manufactured fiber reinforced thermoplastic resin molded article 10 sufficiently exhibits desired characteristics such as impact resistance and rigidity based on the unidirectional material.

In the above example, the fiber-reinforced thermoplastic resin molded article 10 to be manufactured is illustrated as a hollow shape in which two members 20 and 30 having the same shape are joined, but the number of members may be three or more. And it is not limited to a hollow shape. Further, the members to be joined may have different shapes.
The outer fiber reinforced resin layers 23 and 33 in this example include a unidirectional material as a reinforcing fiber. However, a cloth material woven from a unidirectional material is also preferably used as the reinforcing fiber. Examples of the method include plain weave, twill weave, satin weave, and triaxial weave. Furthermore, the reinforcing fibers of the outer fiber reinforced resin layers 23 and 33 only have to have a number average fiber length longer than the reinforcing fibers of the inner fiber reinforced resin layers 24 and 34, and the form of the reinforcing fibers may be continuous fibers or continuous fibers. It is not limited to the unidirectional material which consists of, and cloth material. For example, short fibers may be used as long as the number average fiber length is longer than the reinforcing fibers constituting the inner fiber reinforced resin layers 24 and 34. However, when the reinforcing fibers of the outer fiber reinforced resin layers 23 and 33 are continuous fibers and are in the form of a unidirectional material, a cloth material, or the like, the first member 20 and the second member 30 are more than the case of short fibers. In addition, the fiber-reinforced thermoplastic resin molded article 10 obtained by joining them effectively exhibits excellent physical properties based on the reinforcing fibers.

In this example, the outer fiber reinforced resin layer is composed of one layer, but may be composed of two or more layers. In this case, at least one of the layers constituting the outer fiber reinforced resin layer is included. It is sufficient that the reinforcing fiber has a number average fiber length longer than that of the reinforcing fiber of the inner fiber reinforced resin layer. As long as these conditions are satisfied, there is no limitation on the combination of layers constituting the outer fiber reinforced resin.
For example, when the outer fiber reinforced resin layer is composed of a plurality of layers, each layer may include a unidirectional material and may be laminated so that the fiber directions of adjacent layers are orthogonal to each other, or a layer including a unidirectional material And a layer containing a cloth material may be laminated, or a layer containing a unidirectional material and a layer containing a random material in which bundled short fibers are randomly distributed as reinforcing fibers may be laminated. A layer containing a cloth material and a layer containing a random material may be laminated, or a layer containing a unidirectional material, a layer containing a cloth material, and a layer containing a random material may be laminated.

In addition, the inner fiber reinforced resin layers 24 and 34 are preferably layers in which reinforcing fibers are randomly dispersed as in this example, from the viewpoint of good bonding. However, the inner fiber reinforced resin layers 24 and 34 have non-random dispersion, that is, directivity. It may be distributed.
In this example, the inner fiber reinforced resin layers 24 and 34 and the outer fiber reinforced resin layers 23 and 33 are disposed on the entire surface of the first member 20 and the second member 30. 34 should just be provided so that the to-be-joined surfaces 22a and 32a may be included.

  Furthermore, when the same type of thermoplastic resin is used for the members to be joined, it is preferable because it is easy to join, but if there is no problem in the joining property, a different type of thermoplastic resin is used. May be. Moreover, although the same kind of reinforcing fiber is normally used for the members to be joined, different kinds of reinforcing fibers may be used depending on the purpose.

  In this example, the vibration welding method is exemplified as the joining method, but for example, a hot plate welding method, a resistance welding method, an ultrasonic welding method, or the like may be employed. However, among these, when the vibration welding method is employed, it is preferable that members made of fiber-reinforced thermoplastic resin can be joined better than other methods.

  Such a fiber reinforced thermoplastic resin molded article 10 is used for, for example, automobile parts such as a front subframe, a rear subframe, a front pillar, a center pillar, a side member, a cross member, a side sill, a roof rail, a propeller shaft, and a subsea oil field. Pipes, electric wire cable cores, rolls and pipes for printing presses, robot forks, aircraft primary structural materials, secondary structural materials, and the like.

Hereinafter, the present invention will be specifically described with reference to examples.
[Example 1]
(1) Production of Prepreg for Outer Fiber Reinforced Resin Layers 23, 33 Carbon fibers (manufactured by Mitsubishi Rayon Co., product number: TR50S), which are continuous fibers, were used as reinforcing fibers for the outer fiber reinforced resin layers 23, 33. This carbon fiber is a bundle of 12,000 filaments each having a diameter of about 7 μm.
This carbon fiber bundle is opened and impregnated with maleic anhydride-modified polypropylene (Sanyo Kasei Kogyo Co., Ltd., Umex 1001) as a thermoplastic resin. A continuous carbon fiber reinforced thermoplastic resin tape having a width of 12 mm and a thickness of 100 μm was produced.
Next, this tape was plain woven to produce a prepreg having an average thickness of about 150 μm in which reinforcing fibers made of a cloth material were impregnated with maleic anhydride-modified polypropylene.

(2) Manufacture of Random Sheet 40 for Inner Fiber Reinforced Resin Layers 24 and 34 A continuous carbon fiber reinforced thermoplastic resin tape is manufactured in the same manner as (1) above, and this is cut to a length (fiber length) of 30 mm. Then, they were dispersed and deposited randomly (non-directional) in the plane direction in a pair of flat plate molds. Next, the mold is clamped, and is heated and pressed at a molding temperature of 220 ° C., a molding pressure of 1.0 MPa, and a holding time of 10 minutes, and the mold is cooled to obtain a random sheet 40 having a thickness of 1.85 mm. It was. The volume content of the reinforcing fibers of the random sheet 40 (based on JIS K 7052) was 58%.

(3) Molding The prepreg manufactured in (1) above (width 150 mm, length 400 mm, thickness about 150 μm), and the random sheet (width 150 mm, length 400 mm, thickness about 1.85 mm) manufactured in (2) above A laminated sheet 60 shown in FIG. In FIG. 6, reference numeral 61 is a prepreg layer, and reference numeral 62 is a random sheet layer. This laminated sheet 60 was preheated for 5 minutes by an infrared heater (manufactured by NGK) heated to 270 ° C.
Next, this laminated sheet is placed in the molding die 50 shown in FIG. 4 and molding temperature is 110 ° C. (the temperature of the upper die 51 is 110 ° C., the temperature of the lower die 52 is 110 ° C.), the molding pressure is 15 MPa, the holding time. Heating and pressurizing were performed for 1 minute, the mold 50 was cooled, and the molded article of FIG. 5 was manufactured. The same method was repeated to obtain a total of two molded articles (first member 20 and second member 30).

(4) Joining (vibration welding method)
The molded product obtained in the above (3), that is, the first member 20 and the second member 30 were arranged such that the concave portions 21 and 31 and the edge portions 22 and 32 face each other. Then, using a vibration welding machine (manufactured by Nippon Emerson Co., Ltd.), the surfaces of the opposing edges 22 and 32, that is, the surfaces to be joined 22a and 32a are vibrated and joined (welded). A hollow fiber-reinforced thermoplastic resin molded article 10 was obtained.
The joining conditions were a load of 16 kN, an amplitude of 1.5 mm, a frequency of 230 Hz, and a time of 30 seconds.
Two points at both ends in the longitudinal direction of the fiber reinforced thermoplastic resin molded article 10 were supported from the lower part, and a load of 8 kN was applied to the vicinity of the center from the upper part. Was kept in a good bonding state.
The outer fiber reinforced resin layers 23 and 33 have the same thickness as the prepreg, and the inner fiber reinforced resin layers 24 and 34 have the same thickness as the random sheet 40.

[Comparative example]
Instead of the laminated sheet of Example 1, only the prepreg produced in (1) of Example 1 was used, and the first member was molded and joined in the same manner as in Example 1 without using a random sheet. A second member was produced. And it tried to join the 1st member and the 2nd member by vibration welding method like Example 1, but it cannot join and cannot obtain a hollow fiber reinforced thermoplastic resin molded product. It was.

[Example 2]
A random sheet 40 having a thickness of 1.5 mm was produced in the same manner as in Example 1.
On the other hand, a continuous carbon fiber reinforced thermoplastic resin tape similar to (1) of Example 1 was produced, and the unidirectionally reinforced fibers impregnated with maleic anhydride-modified polypropylene by arranging them in one direction. A prepreg having a thickness of 100 μm was manufactured. Then, as shown in FIG. 7, five prepregs 71 were stacked to manufacture a prepreg laminated sheet 70 having a total thickness of 500 μm. At this time, the reinforcing fibers in each prepreg 71 were laminated alternately so that the fiber directions of the reinforcing fibers were perpendicular to each other in adjacent layers.
Then, a laminate of the prepreg laminated sheet 70 having the five-layer structure shown in FIG. 7 and the random sheet 40 having a thickness of 1.5 mm is placed in the molding die 50 shown in FIG. The first member and the second member were manufactured in the same manner. Then, the first member and the second member were joined by the vibration welding method in the same manner as in Example 1 to obtain a hollow fiber-reinforced thermoplastic resin molded product.
In this molded product, the reinforcing fibers of all the five layers constituting the outer fiber reinforced resin layer have a number average fiber length longer than the reinforcing fibers of the inner fiber reinforced resin layer.
Two points on both ends in the longitudinal direction of this fiber reinforced thermoplastic resin molded product were supported from the lower part, and a load of 8 kN was applied from the upper part near the center. I kept the state.

DESCRIPTION OF SYMBOLS 10 Fiber reinforced thermoplastic resin molded product 20 1st member 30 2nd member 22a, 32a Joined surface 23,33 Outer fiber reinforced resin layer 24,34 Inner fiber reinforced resin layer

Claims (6)

It is a fiber reinforced thermoplastic resin molded product in which a plurality of members are joined at a joint,
Each of the joints comprises an inner fiber reinforced thermoplastic resin layer including a bonded surface, and an outer fiber reinforced thermoplastic resin layer provided outside the inner fiber reinforced thermoplastic resin layer,
The reinforcing fibers contained in the inner fiber reinforced thermoplastic resin layer have a number average fiber length of 5 to 100 mm, and a volume content in the inner fiber reinforced thermoplastic resin layer is 10 to 60%. ,
The outer fiber-reinforced thermoplastic resin layer is composed of at least one layer, and at least one of the reinforcing fibers has a number average fiber length longer than that of the inner fiber-reinforced thermoplastic resin layer,
A fiber-reinforced thermoplastic resin molded article in which the reinforcing fibers joined at the joints are intertwined with each other.   The fiber-reinforced thermoplastic resin molded article according to claim 1, wherein the reinforcing fibers contained in the inner fiber-reinforced thermoplastic resin layer are randomly distributed. Among the outer fiber-reinforced thermoplastic resin layer, the reinforcing fibers of the inner fiber-reinforced thermoplastic resin layer number fiber length average is long at least one layer than reinforcing fibers are continuous fibers, according to claim 1 or 2 fiber-reinforced thermoplastic resin molded article according to. The fiber-reinforced thermoplastic resin molded article according to claim 3 , wherein the continuous fiber is a unidirectional material in which the continuous fibers are aligned in one direction or a cloth material in which the unidirectional material is woven. A method for producing a fiber-reinforced thermoplastic resin molded article in which a plurality of members are joined at a joint,
Each of the joints comprises an inner fiber reinforced thermoplastic resin layer including a bonded surface, and an outer fiber reinforced thermoplastic resin layer provided outside the inner fiber reinforced thermoplastic resin layer,
The reinforcing fibers contained in the inner fiber reinforced thermoplastic resin layer have a number average fiber length of 5 to 100 mm, and a volume content in the inner fiber reinforced thermoplastic resin layer is 10 to 60%. ,
The outer fiber-reinforced thermoplastic resin layer is composed of at least one layer, and at least one of the reinforcing fibers has a number average fiber length longer than that of the inner fiber-reinforced thermoplastic resin layer,
The manufacturing method of the fiber reinforced thermoplastic resin molded product with which the reinforced fiber of the said to-be-joined surfaces joined in each said junction part is intertwined. The method for producing a fiber-reinforced thermoplastic resin molded article according to claim 5 , wherein the joining is performed by a vibration welding method.

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