Method of compression molding to manufacture a shaped body

Abstract

The present application obtains a high impact resistance and solves the problem of "warpage" of a molded body by a method for manufacturing the molded body, in which a molded body is manufactured by using a molding die MA and a molding die MB as a pair of male and female molding dies, contacting a material A with the molding die MA, contacting a material B with the molding die MB, and compression molding, the material A containing carbon fibers and a thermoplastic resin M1, the material B containing glass fibers and a thermoplastic resin M2, the molded body having a pair of side walls and a connecting wall connecting the side walls, the cross section of the molded body having a wavy shape, and the relationship between the flatness Fa of the molded body and the height h of the side wall being 0 ≤ Fa / h < 1.3.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a molded article by laminating and compressing a material A comprising carbon fiber and thermoplastic resin M1 and a material B comprising glass fiber and thermoplastic resin M2. Background Technology Background Technology

[0003] In recent years, molded parts have attracted attention as structural components for automobiles and other products due to their excellent mechanical properties.

[0004] Patent documents 1 and 2 describe molded articles obtained by stacking and molding a thermoplastic resin layer reinforced with glass fiber and a thermoplastic resin layer reinforced with carbon fiber. Patent documents 3 and 4 describe impact-absorbing components with a wave-shaped shape made of thermoplastic resin reinforced with carbon fiber.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2018-43412

[0008] Patent Document 2: International Publication No. 2018 / 052080

[0009] Patent Document 3: US Patent Publication No. 9650003

[0010] Patent Document 4: US Patent No. 9592853 Summary of the Invention

[0011] The technical problem that the invention aims to solve

[0012] However, the material described in Patent Document 1 is a laminated structure made of carbon fiber composite material sandwiched with glass fiber composite material, thus the carbon fiber composite material is disposed on both outer layers. In this case, the elongation at break of the carbon fiber composite material located on both outer layers is small, therefore, for example, it does not meet the rigidity requirement, which is a major performance requirement for automobiles, and the layer on the opposite side of the impacted side is prone to breakage upon impact. Although the glass fiber composite material present in the central layer has a large elongation at break, it does not help prevent cracking upon impact because it is located inside the molded body.

[0013] Although the molded article described in Patent Document 2 is made by laminating glass fiber composite material and carbon fiber composite material in two layers, warping occurs due to the difference in their coefficients of linear expansion. When warping occurs, it is difficult to combine it with other components for assembly, for example, in an automobile.

[0014] The inventions described in Patent Documents 3 and 4 are made of carbon fiber composite materials only, and therefore the issue of warping is not recognized.

[0015] Therefore, the object of the present invention is to provide a method for manufacturing a molded body that solves the problems of high impact resistance and molded body "warping".

[0016] Technical means for solving problems

[0017] To address the aforementioned issues, the present invention provides the following means.

[0018] 1. A method for manufacturing a shaped article, wherein:

[0019] Using forming molds MA and MB, which are a pair of male and female forming dies, material A is brought into contact with forming mold MA and material B is brought into contact with forming mold MB, and compression forming is performed to manufacture a shaped body.

[0020] Material A comprises carbon fiber and thermoplastic resin M1, and material B comprises glass fiber and thermoplastic resin M2.

[0021] The molded body has a pair of sidewalls and a connecting wall connecting the sidewalls.

[0022] The cross-section of the shaped body has a wavy shape.

[0023] The flatness Fa of the shaped body is related to the height h of the sidewall as 0 ≤ Fa / h < 1.3.

[0024] 2. The method for manufacturing the molded article as described in 1 above, wherein,

[0025] The cross-section of the shaped body has multiple wave shapes, and the length of the wave direction is more than 1m.

[0026] 3. The method for manufacturing the molded article as described in any one of 1 to 2 above, wherein,

[0027] The molded body has a pair of sidewalls and a connecting wall connecting the sidewalls.

[0028] The angle θ1 formed by the sidewall and the connecting wall on the side of the shaped body where material B exists on the surface layer satisfies 90 degrees ≤ θ1 < 160 degrees.

[0029] 4. The method for manufacturing the molded article as described in 3 above, wherein,

[0030] The forming die MB has a forming die surface S1 for forming the connecting wall and a forming die surface S2 for forming the side wall, and the angle θ2 formed by S1 and S2 satisfies θ1 < θ2.

[0031] 5. The method for manufacturing the molded article as described in 4 above, wherein,

[0032] When the coefficient of linear expansion of material A is set as Xa and the coefficient of linear expansion of material B is set as Xb, Xa, Xb, θ1 and θ2 satisfy the following equations (1) and (2).

[0033] Equation (1) 0.01≤Xa / Xb<1

[0034] Formula (2) 0≤(θ2-θ1)÷(Xa / Xb)<1.0×10 3

[0035] in,

[0036] The linear expansion coefficient Xa of material A refers to the linear expansion coefficient of the material in the direction of the wave when it has become a shaped body.

[0037] The linear expansion coefficient Xb of material B refers to the linear expansion coefficient of the material in the direction of the wave when it has become a shaped body.

[0038] 6. The method for manufacturing the molded article as described in any one of 1 to 5 above, wherein,

[0039] The flatness Fc of the forming mold cavity used in compression molding satisfies Fa≤Fc.

[0040] 7. The method for manufacturing the molded article as described in 6 above, wherein,

[0041] When the coefficient of linear expansion of material A is set as Xa and the coefficient of linear expansion of material B is set as Xb, the following equations (1) and (3) are satisfied.

[0042] Equation (1) 0.01≤Xa / Xb<1

[0043] Formula (3) 0≤|Fc-Fa| / h÷(Xa / Xb)<1.0×10 3

[0044] in,

[0045] The linear expansion coefficient Xa of material A refers to the linear expansion coefficient of the material in the direction of the wave when it has become a shaped body.

[0046] The linear expansion coefficient Xb of material B refers to the linear expansion coefficient of the material in the direction of the wave when it has become a shaped body.

[0047] 8. The method for manufacturing a molded article as described in any one of 1 to 7 above, wherein,

[0048] When the coefficient of linear expansion of material A is set as Xa and the coefficient of linear expansion of material B is set as Xb, the following equations (1) and (4) are satisfied.

[0049] Equation (1) 0.01≤Xa / Xb<1

[0050] Formula (4) 0<|ta-tb|÷(Xa / Xb)<5000

[0051] Xa: Coefficient of linear expansion of material A

[0052] Xb: Coefficient of linear expansion of material B

[0053] ta: Temperature of the forming mold MA

[0054] tb: Temperature of the forming mold MB

[0055] in,

[0056] The linear expansion coefficient Xa of material A refers to the linear expansion coefficient of the material in the direction of the wave when it has become a shaped body.

[0057] The linear expansion coefficient Xb of material B refers to the linear expansion coefficient of the material in the direction of the wave when it has become a shaped body.

[0058] 9. A method for manufacturing a molded article as described in any one of 1 to 8 above, wherein,

[0059] The forming mold MA is the upper mold, and the forming mold MB is the lower mold.

[0060] 10. A method for manufacturing a molded article as described in any one of 1 to 9 above, wherein,

[0061] The molded body is an impact absorber, and material A is the side subjected to impact.

[0062] 11. The method for manufacturing a molded article as described in any one of 1 to 10 above, wherein,

[0063] Material A has a thickness la of 0.5 mm or more and less than 5.0 mm, and material B has a thickness lb of 0.5 mm or more and less than 3.0 mm.

[0064] 1.3 ≤ la / lb ≤ 3.6 or 0.1 <lb / la<0.6。

[0065] 12. The method for manufacturing a molded article as described in any one of 1 to 11 above, wherein,

[0066] When the linear expansion coefficient of material A is set as Xa and the linear expansion coefficient of material B is set as Xb, the relationship between the fiber volume ratio VfA of material A and the fiber volume ratio VfB of material B satisfies the following equations (1) and (5).

[0067] Equation (1) 0.01≤Xa / Xb<1

[0068] Equation (5) 0.3≤VfA / VfB≤3.0

[0069] in,

[0070] The linear expansion coefficient Xa of material A refers to the linear expansion coefficient of the material in the direction of the wave when it has become a shaped body.

[0071] The linear expansion coefficient Xb of material B refers to the linear expansion coefficient of the material in the direction of the wave when it has become a shaped body.

[0072] 13. The method for manufacturing a molded article as described in any one of 1 to 12 above, wherein,

[0073] Ribs are present between the connecting wall and the side wall.

[0074] 14. The method for manufacturing a molded article as described in any one of 1 to 13 above, wherein,

[0075] Material C lies between material A and material B.

[0076] The linear expansion coefficients Xa of material A, Xb of material B, and Xc of material C are related by the following condition: Xa < Xc < Xb.

[0077] in,

[0078] The linear expansion coefficient Xa of material A refers to the linear expansion coefficient of the material in the direction of the wave when it has become a shaped body.

[0079] The linear expansion coefficient Xb of material B refers to the linear expansion coefficient of the material in the direction of the wave when it has become a shaped body.

[0080] The coefficient of linear expansion Xc of material C refers to the coefficient of linear expansion of the material in the direction of the wave when it has become a shaped body.

[0081] 15. The method for manufacturing a molded article as described in any one of 1 to 14 above, wherein,

[0082] A linear expansion modifier is mixed in so that when the linear expansion coefficient of material A is set as Xa and the linear expansion coefficient of material B is set as Xb, 0.8 ≤ Xa / Xb ≤ 1.

[0083] in,

[0084] The linear expansion coefficient Xa of material A refers to the linear expansion coefficient of the material in the direction of the wave when it has become a shaped body.

[0085] The linear expansion coefficient Xb of material B refers to the linear expansion coefficient of the material in the direction of the wave when it has become a shaped body.

[0086] 16. The method for manufacturing a molded article as described in any one of 1 to 15 above, wherein,

[0087] By using a thermoplastic resin M2 with a smaller coefficient of linear expansion than thermoplastic resin M1, the coefficient of linear expansion of material A is set to Xa and the coefficient of linear expansion of material B is set to Xb, thereby adjusting the coefficient of linear expansion to 0.8 ≤ Xa / Xb ≤ 1.

[0088] in,

[0089] The linear expansion coefficient Xa of material A refers to the linear expansion coefficient of the material in the direction of the wave when it has become a shaped body.

[0090] The linear expansion coefficient Xb of material B refers to the linear expansion coefficient of the material in the direction of the wave when it has become a shaped body.

[0091] 17. The method for manufacturing a molded article as described in any one of 1 to 16 above, wherein,

[0092] The temperature ta of forming mold MA and the temperature tb of forming mold MB are below room temperature +10℃.

[0093] 18. A method for manufacturing a joint, characterized in that,

[0094] Under the condition that the angular stress θ1 of the molded body is reduced and the flatness Fa' of the molded body after stress deformation is related to the height h of the sidewall as 0 ≤ Fa' / h < 0.1, the molded bodies are joined to manufacture a joined body.

[0095] The molded body is manufactured by any one of the manufacturing methods from 1 to 17, the molded body having a pair of sidewalls and a connecting wall connecting the sidewalls, and the material B is present on one side of the surface layer at an angle θ1 formed by the sidewalls and the connecting wall satisfying 90 degrees ≤ θ1 < 160 degrees.

[0096] 19. The method for manufacturing a molded article as described in any one of 1 to 17 above, wherein,

[0097] Material A and material B are stacked and then compressed and formed.

[0098] 20. The method for manufacturing a molded article as described in 19 above, wherein,

[0099] Material A and Material B are flat.

[0100] 21. The method for manufacturing a molded article as described in any one of 19 and 20 above, wherein,

[0101] When materials A and B are formed into a molded body, they form material layer A and material layer B, respectively.

[0102] Invention Effects

[0103] In the molded article manufactured by the method of the present invention, material A, which contains rigid carbon fibers, is used as the surface layer (preferably designed surface) to have rigidity, while the opposite surface layer is made of material B, which contains glass fibers. Therefore, when the material A side of the molded article is subjected to impact, cracks are less likely to form in material B because material B, which exists on the opposite side, has a large elongation at break. Furthermore, the molded article manufactured by the method of the present invention not only has impact resistance but also solves the problem of warping. Attached Figure Description

[0104] Figure 1 This is a schematic diagram illustrating an example of a molded article manufactured by the manufacturing method of the present invention.

[0105] Figure 2 (a) is a schematic diagram showing the open state of a male and female pair of forming molds. Figure 2 (b) is a schematic diagram showing the closed state of a male and female pair of forming molds.

[0106] Figure 3 (a) is a schematic diagram showing the state in which materials (A) and (B) are stacked and compressed using a forming die. Figure 3 (b) is a schematic diagram showing the molded body removed from the mold.

[0107] Figure 4 This is a schematic diagram illustrating an example of a molded article manufactured by the manufacturing method of the present invention.

[0108] Figure 5 (a) is a schematic diagram showing the open state of a male and female pair of forming molds. Figure 5 (b) is a schematic diagram showing the closed state of a male and female pair of forming molds.

[0109] Figure 6 (a) is a schematic diagram showing the state in which materials (A) and (B) are stacked and compressed using a forming die. Figure 6 (b) is a schematic diagram showing the molded body removed from the mold.

[0110] Figure 7 (a) and (b) are schematic diagrams showing a molded body with ribs between the connecting wall and the side wall.

[0111] Figure 8 (a) and (b) are schematic diagrams illustrating the process of deforming the shaped body by stress at angle θ1 and joining it with other components to create a joined body when the shaped body is in the state of angle θ3.

[0112] Figure 9(a) is a schematic diagram of the cross-section of the shaped body with a length Ly of 40cm in the wave direction, which illustrates the method for measuring flatness. Figure 9 (b) is a schematic diagram showing the lower wall. Figure 9 (c) is a schematic diagram showing the lower surface of the lower wall.

[0113] Figure 10 This is a schematic diagram representing the height h of the sidewall.

[0114] Figure 11 This is a schematic diagram illustrating an example of a molded article manufactured by the manufacturing method of the present invention.

[0115] Figure 12 This is a schematic diagram of a method for measuring the flatness Fc of an example forming mold cavity.

[0116] Figure 13 This is a schematic diagram illustrating the phenomenon of warping over time after a model has just been made.

[0117] Symbol Explanation

[0118] A: Material A

[0119] B: Material B

[0120] 101, 401: Sidewall

[0121] 102: Connecting Wall

[0122] 402: Connecting wall of the upper wall (observe with material B positioned on the lower side)

[0123] 403: Connecting wall of the lower wall (observe with material B positioned on the lower side)

[0124] X: X-axis direction

[0125] Y: Y-axis direction

[0126] Z: Z-axis direction

[0127] θ1: The angle formed by the sidewall and the connecting wall

[0128] θ2: The angle between the forming die surface S1, which forms the connecting wall, and the forming die surface S2, which forms the sidewall, in the forming die MB.

[0129] θ3: The angle formed by the sidewall and the connecting wall when the formed body is joined by stress deformation at angle θ1.

[0130] MA: Mold that brings material A into contact with the mold

[0131] MB: Mold that brings material B into contact with the mold

[0132] 701: Ribs

[0133] 801: The force used to cause stress deformation

[0134] 802: Other components used for joining

[0135] 901: Two parallel ideal straight lines

[0136] 902: Lower wall of the connecting wall

[0137] 903: Bottom surface of the lower wall

[0138] Ly: Length in the direction of the wave (40cm)

[0139] h: Height of the sidewall

[0140] Lyc: Length in the wave direction (40cm)

[0141] 1201: Forming die surface used to form the lower wall

[0142] 1202: Two parallel ideal lines

[0143] T1, T2: formed body Detailed Implementation

[0144] [Material]

[0145] In this specification, material A, material B, or material C are sometimes referred to simply as "material". "Material" refers to material A, material B, or material C, or a layered structure of material A / material B, etc., composed of multiple materials.

[0146] Materials A and B are preferably flat plates. More preferably, after the flat plates A and B are stacked and compressed to form a molded body, material layer A and material layer B are formed respectively. The flat plate material forms a single layer when it becomes a molded body.

[0147] [Materials A and B]

[0148] Material A contains carbon fiber and thermoplastic resin M1, and material B contains glass fiber and thermoplastic resin M2.

[0149] The molded body of the present invention is manufactured using a pair of male and female molding dies, namely molding die MA and molding die MB, by compression molding of material A with molding die MA and material B with molding die MB. In other words, one surface of the molded body is material A, and the opposite surface is material B. The layering structure of the materials is not particularly limited; it can be A / B, a 4-layer structure of A / B / A / B, or a 6-layer structure of A / B / A / B / A / B. Here, "A" and "B" refer only to the individual layers.

[0150] One surface of the molded body is made of Material A, and the surface on the opposite side is made of Material B. Thus, especially when an impact is applied to the surface of Material A, since the breaking elongation rate of Material B in the surface layer on the opposite side is large, cracks are not easily generated in Material B, which is preferable in this regard. However, if it is only Material B, the rigidity of the molded body is insufficient. Therefore, it is necessary to dispose Material A containing carbon fiber on the surface layer on one side. In other words, the molded body manufactured by the manufacturing method of the present invention is an impact-resistant absorber, and preferably, the molded body is such that Material A becomes the surface receiving the impact. The molded body is preferably for automotive parts that require both rigidity and impact resistance.

[0151] On the other hand, as described in, for example, Japanese Patent Application Laid-Open No. 2018-43412, in the case of a line-symmetric layer structure such as an A / B / A structure in which Material B containing glass fiber is sandwiched by Material A containing carbon fiber, or B / A / B, the difference in the linear expansion coefficient is canceled out, so it is easy to suppress warping of the molded body, but there are the following problems.

[0152] In the case of A / B / A, when an impact is applied, since the surface layer on the side opposite to the side receiving the impact is a carbon fiber composite material, cracks are easily generated. In the case of B / A / B, since the surface layer contributing to rigidity does not contain carbon fiber, the molded body does not have sufficient rigidity. If Material A is present in the central layer, it hardly contributes to ensuring the rigidity of the molded body.

[0153] [Thickness of Material A and Material B]

[0154] The thicknesses of Material A and Material B are not particularly limited. Preferably, the thickness la of Material A is 0.5 mm or more and less than 5.0 mm, the thickness of Material B is 0.5 mm or more and 3.0 mm or less, and preferably 1.3 ≤ la / lb ≤ 3.6 or 0.1 < lb / la < 0.6. More preferably, 1.3 ≤ la / lb ≤ 1.8 or 0.1 < lb / la < 0.2. If it is within this range, even if there is a difference in the linear expansion coefficient between the materials, this difference is not easily manifested as warping.

[0155] The upper limit of the thickness la of Material A is more preferably 4.0 mm or less, and further preferably 3.0 mm or less.

[0156] The upper limit of the thickness lb of Material B is more preferably 2.0 mm or less, further preferably 1.5 mm or less, and even more preferably 1.0 mm or less.

[0157] Inside the molded body after compression molding, the thicknesses of the materials of each layer can be uniform. In other words, the compression molding of the present invention is non-flow molding, and the material can be filled in the molding die at a filling rate of 100% or more for compression molding.

[0158] Wherein, the fill rate (%) = 100 × the projected area (mm²) of material A and material B after being stacked. 2 ) / Cavity area of ​​forming mold (mm) 2 ).

[0159] If materials A and B are flat, the projected area can be easily measured.

[0160] [Material C]

[0161] As the material used in manufacturing the molded body of the present invention, material C can be present between material A and material B. In this case, the relationship between the linear expansion coefficient Xa of material A, the linear expansion coefficient Xb of material B, and the linear expansion coefficient Xc of material C preferably satisfies Xa < Xc < Xb. Alternatively, Xa < Xb < Xc or Xc < Xa < Xb may also be present. The layer structure is not only a three-layer structure of A / C / B, but also a four-layer structure such as A / C / A / B, A / B / C / B, or a five-layer structure such as A / C / B / A / B, or A / B / A / C / B. Here, "A," "B," and "C" refer only to each layer.

[0162] However, the molding body in this invention is manufactured using a pair of male and female molding dies, namely molding die MA and molding die MB, by bringing material A into contact with molding die MA and material B into contact with molding die MB to perform compression molding. Therefore, even with material C, one surface of the molding body is still material A, and the opposite surface is material B.

[0163] Of course, the molded body can also have materials other than material C, such as material D.

[0164] [Carbon fiber]

[0165] Material A comprises carbon fiber. Commonly known carbon fibers include polyacrylonitrile (PAN)-based carbon fibers, petroleum-coal tar-based carbon fibers, rayon-based carbon fibers, cellulose-based carbon fibers, lignin-based carbon fibers, and phenolic carbon fibers; however, in this invention, any of these carbon fibers may be preferred. In particular, from the perspective of excellent tensile strength, polyacrylonitrile (PAN)-based carbon fibers are preferred in this invention.

[0166] [Fiber diameter of carbon fiber]

[0167] The fiber diameter of the carbon fiber monofilaments (sometimes referred to as filaments) used in this invention can be appropriately determined according to the type of carbon fiber and is not particularly limited. The average fiber diameter is generally preferably in the range of 3 μm to 50 μm, more preferably in the range of 4 μm to 12 μm, and even more preferably in the range of 5 μm to 8 μm. When the carbon fiber is in the form of a fiber bundle, the diameter refers not to the diameter of the fiber bundle, but to the diameter of the carbon fiber (monofilament) constituting the fiber bundle. The average fiber diameter of the carbon fiber can be measured, for example, by the method described in JISR-7607:2000.

[0168] [Glass fiber]

[0169] Material B includes glass fiber. The type of glass fiber is not particularly limited; any type of glass fiber containing E glass, A glass, or C glass can be used, or they can be mixed. There is no particular limitation on the glass fiber used in this invention; the average fiber diameter is preferably 1 μm to 50 μm, more preferably 5 μm to 20 μm.

[0170] [Sizing agent]

[0171] The carbon fiber or glass fiber used in this invention may have a sizing agent attached to its surface. When using reinforcing fibers with an attached sizing agent, the type of sizing agent may be appropriately selected according to the type of reinforcing fiber and the type of matrix resin, without particular limitation.

[0172] [Weight-average fiber length]

[0173] Carbon fiber is a discontinuous fiber, and its weight-average fiber length is preferably 1 mm or more and 100 mm or less. Similarly, glass fiber is a discontinuous fiber, and its weight-average fiber length is preferably 1 mm or more and 100 mm or less. Although continuous fibers are preferred to eliminate warping problems, the above-mentioned range of weight-average fiber lengths is preferred from the viewpoint of improving formability.

[0174] Hereinafter, glass fiber and / or carbon fiber will be collectively referred to as "reinforcing fiber". In other words, reinforcing fiber is at least one of glass fiber and carbon fiber.

[0175] The weight-average fiber length of the reinforcing fiber is more preferably 5 mm or more and 100 mm or less, further preferably 5 mm or more and 80 mm or less, and even more preferably 10 mm or more and 60 mm or less. When the weight-average fiber length of the reinforcing fiber is 100 mm or less, the flowability of material A and / or material B is improved, and the desired molded shape is easily obtained during compression molding. On the other hand, when the weight-average fiber length is 1 mm or more, the mechanical strength of the molded article is easily improved.

[0176] In this invention, reinforcing fibers with different fiber lengths can also be used together. In other words, the reinforcing fibers may have a single peak in the weight-average fiber length, or they may have multiple peaks.

[0177] The average fiber length of the reinforcing fiber can be measured to 1 mm using, for example, calipers, by randomly selecting 100 fibers from the molded body and calculated based on the following formula (a). The average fiber length is determined using the weight-average fiber length (Lw).

[0178] When the fiber length of each reinforcing fiber is set as Li and the number of fibers measured is set as j, the number-average fiber length (Ln) and weight-average fiber length (Lw) are obtained by the following equations (a) and (b).

[0179] Ln=ΣLi / j (a)

[0180] Lw=(ΣLi 2 ) / (ΣLi)Formula (b)

[0181] It should be noted that when the fiber length is a certain length, the number-average fiber length and the weight-average fiber length are the same value.

[0182] Reinforcing fibers can be extracted from the molded body, for example, by subjecting the molded body to a heat treatment at 500°C for about 1 hour, and removing the resin in the furnace.

[0183] [Fiber volume ratio VfA of material A and fiber volume ratio VfB of material B]

[0184] In this invention, the volume ratio of fibers contained in material A or material B is not particularly limited, but preferably satisfies formulas (1) and (5).

[0185] Equation (1) 0.01≤Xa / Xb<1

[0186] Equation (5) 0.3≤VfA / VfB≤3.0

[0187] The upper limit of equation (5) is more preferably VfA / VfB≤1.6, further preferably VfA / VfB≤1.0, and even more preferably VfA / VfB≤0.8.

[0188] The lower limit of equation (5) is more preferably 0.4≤VfA / VfB, even more preferably 0.5≤VfA / VfB, and even more preferably 0.6≤VfA / VfB.

[0189] By satisfying equation (5), the warping problem can be further eliminated.

[0190] It should be noted that the fiber volume ratio is defined by the following formulas (c) and (d). In this specification, the fiber volume ratio of material A or material B is sometimes referred to as VfA or VfB, respectively.

[0191] Fiber volume ratio (VfA) = 100 × carbon fiber volume / (carbon fiber volume + thermoplastic resin volume of material A) Equation (c)

[0192] Fiber volume ratio (VfB) = 100 × glass fiber volume / (glass fiber volume + thermoplastic resin volume of material B) (d)

[0193] More specifically, the fiber volume fraction (VfA) is preferably 10 Vol% or more and 60 Vol% or less, more preferably 20 Vol% or more and 50 Vol% or less, and even more preferably 25 Vol% or more and 45 Vol% or less.

[0194] The fiber volume percentage (VfB) is preferably 10 Vol% or more and 60 Vol% or less, more preferably 20 Vol% or more and 50 Vol% or less, and even more preferably 25 Vol% or more and 45 Vol% or less.

[0195] When the volume percentage (VfA, VfB) of reinforcing fibers in material A or material B is 10 Vol% or more, the desired mechanical properties are easily obtained. On the other hand, when the volume percentage (VfA, VfB) of reinforcing fibers does not exceed 60 Vol%, the material exhibits good flowability when used in stamping and the like, and the desired molded shape is easily obtained.

[0196] [Fiber morphology of material A]

[0197] 1. Bundle morphology

[0198] The carbon fiber is a discontinuous fiber with a fiber length of 5 mm or more, preferably comprising carbon fiber a1 with a fiber bundle of less than 0.3 mm and carbon fiber bundle a2 with a bundle width of 0.3 mm or more and less than 3.0 mm. The volume ratio of carbon fiber bundle a2 to the carbon fiber contained in material A is preferably 5 vol% or more and less than 95 vol%, more preferably 10 vol% or more and less than 90 vol%.

[0199] 2. Disperse

[0200] In material A, the carbon fibers are preferably dispersed in the in-plane direction. The in-plane direction refers to the direction orthogonal to the thickness direction of the formed body, and is a variable direction of a parallel plane orthogonal to the thickness direction.

[0201] Furthermore, the carbon fibers are preferably randomly dispersed in the two-dimensional direction in the in-plane direction. When compression molding is performed without causing material A to flow, the morphology of the carbon fibers is substantially maintained before and after molding. Therefore, the carbon fibers contained in the molded body formed from material A are also preferably randomly dispersed in the two-dimensional direction in the in-plane direction of the molded body.

[0202] Here, "two-dimensional random dispersion" refers to the fact that the carbon fibers are not oriented in a specific direction in the in-plane direction of the molded body, but are randomly oriented, and are arranged in the plane of the sheet without exhibiting a specific directionality as a whole. The material A (or molded body) obtained by using the two-dimensional random dispersion discontinuous fibers is a material A (or molded body) that is not anisotropic in the plane, but is substantially isotropic.

[0203] It should be noted that the degree of two-dimensional random orientation is evaluated by calculating the ratio of the tensile modulus of elasticity in two mutually orthogonal directions. For any direction of the molded body and the direction orthogonal to it, if the ratio (Eδ) obtained by dividing the larger of the measured tensile modulus of elasticity by the smaller value is 5 or less, more preferably 2 or less, and even more preferably 1.5 or less, then the carbon fibers can be evaluated as being dispersed in a two-dimensional random manner. Since the molded body has a shape, as a method for evaluating two-dimensional random dispersion in the in-plane direction, it is preferable to heat it to above the softening temperature to restore it to a flat plate shape and then cure it. Afterwards, by cutting the test piece and calculating the tensile modulus of elasticity, the random dispersion state in the two-dimensional direction can be confirmed.

[0204] [Fiber morphology of material B]

[0205] In material B, the glass fibers are preferably dispersed in the in-plane direction. The in-plane direction refers to the direction orthogonal to the thickness direction of the formed body, and is a variable direction of a parallel plane orthogonal to the thickness direction.

[0206] Furthermore, it is preferable that the glass fibers are randomly dispersed in the two-dimensional direction in the in-plane direction. When compression molding is performed without causing material B to flow, the morphology of the glass fibers is substantially maintained before and after molding. Therefore, the glass fibers contained in the molded body formed from material B are also preferably randomly dispersed in the two-dimensional direction in the in-plane direction of the molded body.

[0207] Here, "two-dimensional random dispersion" refers to the state in which the glass fibers are not oriented in a specific direction in the in-plane direction of the molded body, but are randomly oriented, and are arranged in the sheet surface without exhibiting a specific directionality as a whole. The material B (or molded body) obtained by using this two-dimensional randomly dispersed discontinuous fiber is a material B (or molded body) that is substantially isotropic and does not have anisotropy in the plane.

[0208] It should be noted that the degree of two-dimensional random orientation is evaluated by calculating the ratio of the tensile modulus of elasticity in two mutually orthogonal directions. For any direction of the molded body and the direction orthogonal to it, if the ratio (Eδ) obtained by dividing the larger of the measured tensile modulus of elasticity by the smaller value is 5 or less, more preferably 2 or less, and even more preferably 1.5 or less, then the glass fibers can be evaluated as being randomly dispersed in two dimensions. Since the molded body has a shape, as a method for evaluating the two-dimensional random dispersion in the in-plane direction, it is preferable to heat it to above the softening temperature to restore it to a flat plate shape and then cure it. Afterwards, if the tensile modulus of elasticity is calculated by cutting the test piece, the random dispersion state in the two-dimensional direction can be confirmed.

[0209] [Thermoplastic Resin M1]

[0210] The type of thermoplastic resin M1 used in this invention is not particularly limited, and a resin with a desired softening point or melting point can be appropriately selected. As the matrix resin for the above-mentioned thermoplastic resin, a resin with a softening point in the range of 180°C to 350°C is generally used, but it is not limited thereto.

[0211] Examples of thermoplastic resins M1 include: vinyl chloride resins, vinylidene chloride resins, vinyl acetate resins, polyvinyl alcohol resins, polystyrene resins, acrylonitrile-styrene resins (AS resins), acrylonitrile-butadiene-styrene resins (ABS resins), acrylic resins, methacrylic resins, polyethylene resins, polypropylene resins, various thermoplastic polyamide resins, polyacetal resins, polycarbonate resins, polyethylene terephthalate resins, polyethylene naphthalate resins, polybutylene naphthalate resins, polybutylene terephthalate resins, polyarylate resins, polyphenylene ether resins, polyphenylene sulfide resins, polysulfone resins, polyethersulfone resins, polyetheretherketone resins, polylactic acid resins, etc.

[0212] The thermoplastic resin in this invention can be either a crystalline resin or an amorphous resin. In the case of a crystalline resin, preferred crystalline resins include: polyamide resins such as nylon 6, polyethylene terephthalate resins, polybutylene terephthalate resins, polyethylene resins, polypropylene resins, polyacetal resins, and polyphenylene sulfide resins. Among these, polyamide resins, polybutylene terephthalate resins, and polyphenylene sulfide resins are preferred due to their excellent heat resistance and mechanical strength.

[0213] Nylon (hereinafter, sometimes simply referred to as "PA"), a type of polyamide resin, is preferably derived from PA6 (also known as polyhexamethylene, polycaprolactam, poly-ε-caprolactam), PA26 (polyvinylhexamethylene adipamide), PA46 (polytetramethylene adipamide), PA66 (polyhexamethylene adipamide), PA69 (polyhexamethylene nonadiamide), PA610 (polyhexamethylene decanedamide), PA611 (polyhexamethylene undecylamide), PA612 (polyhexamethylene dodecylamide), PA11 (polyundecylamide), PA12 (polydodecylamide), PA1212 (polydodecylamide), PA6T (polyhexamethylene terephthalamide), P At least one selected from the group consisting of A6I (polyhexamethylene isophthalamide), PA912 (polynonamethylene dodecylamide), PA1012 (polydemomethyl dodecylamide), PA9T (polynonamethylene terephthalamide), PA9I (polynonamethylene isophthalamide), PA10T (polydemomethyl terephthalamide), PA10I (polydemomethyl isophthalamide), PA11T (polyundumethylene terephthalamide), PA11I (polyundumethylene isophthalamide), PA12T (polydodecyl terephthalamide), PA12I (polydodecyl isophthalamide), and polyamide MXD6 (polyadipamide).

[0214] [Thermoplastic Resin M2]

[0215] The thermoplastic resin M2 in this invention is similar to other thermoplastic resins, and its type is not particularly limited. Resins with desired softening points or melting points can be appropriately selected. As the base resin for the aforementioned thermoplastic resin, resins with softening points in the range of 180°C to 350°C are generally used, but are not limited thereto.

[0216] Thermoplastic resin M2 can be the same type as thermoplastic resin M1, or it can be thermoplastic resin M2 with a smaller coefficient of linear expansion than thermoplastic resin M1, so that when the coefficient of linear expansion of material A is set to Xa and the coefficient of linear expansion of material B is Xb, it is adjusted to 0.8≤Xa / Xb≤1.

[0217] [Linear expansion buffer]

[0218] When the coefficient of linear expansion of material A is set to Xa and the coefficient of linear expansion of material B is set to Xb, a linear expansion modifier can also be mixed into material A and / or material B so that 0.8≤Xa / Xb≤1.

[0219] [Other additives]

[0220] Without prejudice to the purpose of the present invention, material A or material B used in the present invention may contain various fibrous or non-fibrous fillers, flame retardants, UV resistant agents, stabilizers, release agents, pigments, softeners, plasticizers, surfactants, hollow glass beads and other additives, including organic or inorganic fibers.

[0221] [Direction for determining the coefficient of linear expansion]

[0222] The "warping" of a molded body during compression molding refers to the deformation of the molded body after a period of time following compression molding, when the temperature decreases. Typically, it is a stretching phenomenon that occurs immediately after molding, with the material having a larger coefficient of linear expansion (B) over time. For example, ... Figure 13 Like the newly formed molded body above, this is a phenomenon where the ends of the molded body in the corrugated direction (wave direction) deform downwards along the Z-axis. This is because the wave direction of materials A and B (the direction in which one sidewall of a pair of sidewalls is opposite to the other, for example...) Figure 13 The coefficient of linear expansion differs between the wave direction of the shaped body below (which is the Y-axis direction). Therefore, the coefficient of linear expansion is defined as follows.

[0223] The linear expansion coefficient Xa of material A refers to the linear expansion coefficient of the material in the direction of the wave when it is formed into a shaped body.

[0224] The linear expansion coefficient Xb of material B refers to the linear expansion coefficient of the material in the direction of the wave when it is formed into a shaped body.

[0225] The linear expansion coefficient Xc of material C refers to the linear expansion coefficient of the material in the direction of the wave when it is formed into a shaped body.

[0226] It should be noted that the coefficient of linear expansion of the material as a solid (especially in the case of non-flow forming) is approximately the same as that of the material after it becomes a molded body. Therefore, the coefficient of linear expansion can be measured either by examining samples taken from the molded body. When sampling from the connecting walls of the molded body, it is... Figure 13 The direction of the waves ( Figure 13 The Y-axis direction), but when sampling from the vertical wall (side wall), it is different from the wave direction ( Figure 13 Compared to the Y-axis, it becomes the direction of travel ( Figure 13 (Z-axis direction).

[0227] [Relationship between material and molded part]

[0228] In this invention, the material is used to form the molded body. Material A, material B (or other layers such as material C) are compressed and molded to form the molded body. Therefore, material A and material B in this invention are preferably flat. In contrast, the molded body is shaped into a three-dimensional shape.

[0229] When using thermoplastic resin for compression molding (especially cold pressing), the morphology of the reinforcing fibers is largely maintained before and after molding. Therefore, by analyzing the morphology of the carbon fibers and glass fibers contained in the molded body, we can know the morphology of the carbon fibers and glass fibers in material A and material B. During cold pressing, if molding is performed without allowing the material to flow (non-flow molding), the fiber morphology remains almost unchanged.

[0230] [molded body]

[0231] 1. Side walls and connecting walls

[0232] The molded body of the present invention has a pair of sidewalls and a connecting wall connected to the sidewalls.

[0233] Sidewalls, for example, are Figure 1 , Figure 4 101 and 401 in the example. Connecting walls, for example, are... Figure 1 , Figure 4 102, 402, 403. For example... Figure 1 , Figure 4 As shown, the connecting wall connects a pair of sidewalls.

[0234] like Figure 4 As shown, the connecting wall is a concept that includes the connecting wall (402) of the upper wall and the connecting wall (403) of the lower wall. Upper wall ( Figure 4 402) refers to the connecting wall located on the upper side when the molded body is placed at rest with the material B present on the surface as the lower side. Lower wall ( Figure 4 403) refers to the connecting wall located on the lower side when the molded body is placed at rest with the material B existing on the surface as the lower side.

[0235] 2. Wave shape

[0236] The shaped body in this invention has a wavy cross-section. Here, the wavy cross-section is as follows: Figure 1 As illustrated in the sectional view, the wave can be single. Preferably, the cross-section of the shaped body has multiple wave shapes (e.g., Figure 4 Preferably, the length in the wave direction is 1m or more; more preferably, the cross-section of the shaped body has multiple wave shapes and the length in the wave direction is 1m or more. The wave direction referred to here is, for example,... Figure 4The Y-axis direction. A shaped body with a wavy cross-section refers to a shaped body in which undulations can be observed when viewed in cross-section. It is generally observed in the in-plane direction (the direction perpendicular to the thickness direction).

[0237] 3. Flatness Fa and sidewall height h

[0238] The flatness Fa of the molded body of the present invention is related to the height h of the sidewall as 0 ≤ Fa / h < 1.3. 3.1

[0240] The flatness Fa of the present invention is defined by the following steps 1-5.

[0241] (Step 1) The body is statically shaped with the material B present on the surface as the bottom.

[0242] (Step 2) Observe the cross section of the formed object in a way that the cross section looks like a wave shape, and cut the observation range of the formed object in such a way that the length Ly in the wave direction reaches 40cm.

[0243] (Step 3) Focus on the bottom surface of the lower wall formed by the connecting wall.

[0244] (Step 4) Draw two parallel ideal lines with the minimum required width, in a manner that includes the bottom surface of all the lower walls.

[0245] (Step 5) Define the distance between ideal straight lines as flatness Fa.

[0246] use Figure 9 Steps 1 through 5 will be explained.

[0247] Figure 9 This refers to a molded body that is placed at rest with material B, which exists on the surface, as the lower side. The surface of the molded body on the lower side of the paper is covered by material B. Figure 9 The Y-axis direction is the wave direction, in Figure 9 In (a), the observation area of ​​the shaped body is cut with a length Ly reaching 40cm, showing the cross-section of the wave shape (step 2). The lower wall of the connecting wall refers to... Figure 9 The area shown in 902. Additionally, the bottom surface of the lower wall is... Figure 9 The surface shown in 903 (step 3). Two parallel ideal lines are formed by... Figure 9 Example 901. Two parallel ideal lines (901) are drawn in a way that minimizes the distance between them (the two parallel ideal lines are drawn with the minimum required width).

[0248] In addition, Figure 9The method of observing and measuring the molded body with its top and bottom reversed and the surface of the molded body on the underside of the paper covered by material A (with material A in contact with the table) is not used in this invention.

[0249] When Fa varies depending on the location of the cut of the length Ly in the wave direction, Fa can be designed in such a way that 0≤Fa / h<1.3 is satisfied at point 1. 3.2

[0251] The height h of the sidewall of the present invention is determined by Figure 10 The example of h refers to the distance between the upper and lower walls when observing a cross-section of a wave shape. More specifically, when observing an upper and lower wall directly connected to a sidewall, the height h is the distance between two ideal lines drawn with the necessary minimum width to encompass both the upper and lower walls. Figure 10 The two dashed lines depicted in the middle are drawn in such a way that the interval between them is minimized.

[0252] When the shaped body has multiple heights h, at least one h must satisfy 0≤Fa / h<1.3. 3.3

[0254] When Fa / h = 0, the lower wall of the molded body becomes an ideal plane. If Fa / h < 1.3, it is easy to combine with other parts, such as easy to assemble a car. Preferably, 0 ≤ Fa / h ≤ 1.0, more preferably 0 ≤ Fa / h ≤ 0.7, further preferably 0 ≤ Fa / h ≤ 0.4, and even more preferably 0 ≤ Fa / h ≤ 0.1.

[0255] 4. Angle θ1

[0256] The preferred material B of the molded body has an angle θ1 formed by the sidewall and the connecting wall on one side of the surface layer that is 90 degrees ≤ θ1 < 160 degrees. For example, the angle θ1 formed by the sidewall and the connecting wall on one side of the surface layer where material B exists is... Figure 1 , Figure 4 θ1 represents the angle θ1. That is, when observing the cross-section of a wave shape, the angle θ1 can be determined.

[0257] in addition, Figure 1 , Figure 4 The shaped body has multiple identical angles θ1. When multiple angles θ1 exist and each is a different angle, the angle with the smallest angle formed by the sidewall and the connecting wall on one side of the material B that exists on the surface is taken as angle θ1.

[0258] More preferably, the range of angle θ1 is 95 degrees ≤ θ1 < 135 degrees, even more preferably 95 degrees ≤ θ1 < 125 degrees, and even more preferably 98 degrees ≤ θ1 < 120 degrees.

[0259] 5. Angular variation based on the difference in linear expansion coefficients

[0260] Since materials A and B of this invention contain carbon fiber and glass fiber respectively, their coefficients of linear expansion differ. Let the coefficient of linear expansion of material A be Xa and that of material B be Xb, and assuming all other conditions are the same (VfA = VfB, the types of thermoplastic resins M1 and M2 are the same, etc.), Xa / Xb < 1.

[0261] When materials A and B have different coefficients of linear expansion, and when materials A and B are stacked and formed into a wavy shape at a temperature higher than room temperature, the layer with the larger coefficient of linear expansion will stretch the layer with the smaller coefficient of linear expansion. Specifically, when Xa / Xb < 1, material B stretches material A, therefore, for example, in... Figure 3 , Figure 6 Immediately after compression molding, over time, the two ends (in the wavy direction) of the molded body warp downwards towards the paper. As a result, the angle formed by the sidewall and the connecting wall on one side of material B present on the surface changes immediately after molding and after a period of time (sometimes referred to as "angle change"). To make the angle θ1 of the molded body the target angle, the degree of angle change needs to be predicted in advance.

[0262] For the change in angle immediately after forming and after a period of time (angle change), the longer the length in the wave direction (specifically, if the length in the wave direction is more than 1m), the more the number of angles θ1 increases, and the more significant the overall warping problem of the molded body becomes. If the preferred manufacturing method of the present invention is used, even with such significant problems, it is possible to manufacture molded bodies with a small Fa / h value.

[0263] 6. Ribs

[0264] The molded body in this invention preferably has ribs between the connecting wall and the sidewall. The ribs are, for example, made of... Figure 7 Examples 701 in (a) and (b). By configuring ribs, warping is not easily prevented even when compressing materials A and B, which have different coefficients of linear expansion.

[0265] [Assembly]

[0266] Alternatively, a joined body can be manufactured by joining it with other components under the condition that the stress at angle θ1 is reduced by deformation, and the flatness Fa' of the deformed body after stress deformation is related to the height h of the sidewall in the condition that 0 ≤ Fa' / h < 0.1. For example, it can also be like... Figure 8 (a) In that case, in such Figure 8 (a) As shown by arrow 801, stress is applied to the slightly warped molded body, in conjunction with other components ( Figure 8802) joint. Here, flatness Fa' refers to the flatness of the molded body in the joined state. The joint can be as follows: Figure 8 (b) Bolts can be tightened in that way, or they can be bonded with adhesive.

[0267] Compression molding

[0268] The present invention is a method as follows: using a pair of male and female forming molds, namely forming mold MA and forming mold MB, material A is brought into contact with forming mold MA and material B is brought into contact with forming mold MB to perform compression forming and manufacture a shaped body. Figure 3 (a) and Figure 6 (a) shows a state where material A is in contact with mold MA and material B is in contact with mold MB. Here, mold MA and mold MB, as a male-female pair, are not two molds that are each a male-female pair; rather, mold MA and mold MB are single molds, forming a male-female pair. Additionally, for example... Figure 2 As shown, it is sufficient if one single mold has a male part and the other single mold has a female part. Alternatively, the two forming molds can each have male and female parts (convex and concave or concave and convex).

[0269] 1. Upper and lower parts of the forming mold

[0270] There are no particular limitations on the upper and lower positions of the forming molds MA and MB, but preferably MA is the upper mold and MB is the lower mold. Further preferably, compression forming is cold pressing, with MA as the upper mold and MB as the lower mold. The reasons are as follows.

[0271] (Reason 1)

[0272] During cold pressing, the upper and lower forming molds are at lower temperatures compared to materials A and B. Therefore, the thermoplastic resin in the material solidifies instantly upon contact with the mold. Material A contains a carbon fiber layer, resulting in high thermal conductivity. Compared to material B, which contains glass fiber, it cools more easily under the same conditions (resin, additives, Vf, etc.), thus exhibiting poor flowability. Therefore, preventing the temperature of material A from dropping during cold pressing becomes a challenge.

[0273] When cold-pressing a material formed by stacking materials A and B, to ensure flowability, it is preferable to ensure that material A does not come into contact with the forming die MA just before compression begins. Therefore, it is preferable to position material B in contact with the lower forming die MB, and position material A in contact with the upper die for compression forming. In this case, material A does not come into contact with the forming die before compression forming, thus easily preventing temperature drop.

[0274] (Reason 2)

[0275] Material A, containing carbon fiber, has an attractive appearance, and its presence on the surface makes it highly appealing to customers. In particular, its design appeal is especially pronounced when material A has a texture. To create a texture on material A, compression molding is required immediately after material A comes into contact with the forming mold MA. At this point, the forming mold MA becomes the upper mold.

[0276] 2. Compression molding

[0277] Compression forming can be performed using forming methods such as hot pressing and cold pressing, with cold pressing being particularly preferred. Cold pressing involves, for example, placing a molded body heated to a first predetermined temperature into a forming mold set to a second predetermined temperature, followed by pressurization and cooling.

[0278] Specifically, when the thermoplastic resins constituting material A and material B (and, depending on the case, material C, etc.) are of the same type and are crystalline, the first specified temperature is above the melting point, and the second specified temperature is below the melting point. When the thermoplastic resins are of the same type and are amorphous, the first specified temperature is above the glass transition temperature, and the second specified temperature is below the glass transition temperature.

[0279] When the thermoplastic resins are different, a first specified temperature is determined based on the resin with the higher melting point or glass transition temperature, and a second specified temperature is determined based on the resin with the lower melting point or glass transition temperature.

[0280] That is, the cold pressing method includes at least the following processes A2) to A1).

[0281] Process A1) is the process of heating the material to a first specified temperature.

[0282] Step A2) involves placing the material heated in step A1) into a forming mold that has been adjusted to a second specified temperature and then applying pressure.

[0283] By performing these processes, the molding of the object can be completed.

[0284] The above-described processes must be performed in the order described above, but other processes may be included between each process. Other processes include, for example, a shaping process prior to process A2), using a different forming mold than the forming mold used in process A2), to pre-shape the material to the cavity shape of the forming mold. Furthermore, process A2) is the process of applying pressure to the material to obtain a molded body of the desired shape. The forming pressure is not particularly limited, but it is preferably less than 20 MPa, more preferably less than 10 MPa, relative to the projected area of ​​the forming mold cavity.

[0285] Alternatively, various processes can be incorporated between the aforementioned processes during compression forming; for example, vacuum stamping can be used while compression forming is performed under vacuum.

[0286] 3. Preferred temperature for forming mold

[0287] The temperatures ta of the forming mold MA and tb of the forming mold MB can be either room temperature +10°C or above room temperature but below room temperature +10°C. In this case, the molded body reaches a temperature close to room temperature at the same time as the forming is completed, and there is no shrinkage of each layer caused by the temperature difference between the molded body and room temperature. Therefore, even if there is a difference in the coefficient of linear expansion between material A and material B, warping is not likely to occur.

[0288] [Forming dies used for compression molding]

[0289] 1. Angle θ2

[0290] Preferably, the forming die MB has a forming die surface S1 for forming the connecting wall and a forming die surface S2 for forming the side wall, and the angle θ2 formed by S1 and S2 satisfies θ1 < θ2.

[0291] Angle θ2 is obtained by measuring the obtuse portion of the angle formed by S1 and S2. For example, in Figure 3 , Figure 6 In the process, the obtuse angle of the lower forming die (forming mold MB) in contact with material B is measured.

[0292] The mold cavity preferably has a wavy cross-section. When the mold cavity is observed to be wavy in the cross-section, the angle θ2 can be measured.

[0293] in addition, Figure 3 , Figure 6 The molding chamber has multiple identical angles θ2. When multiple angles θ2 exist and each is a different angle, the angle with the smallest angle between the molding die surface S1 and the molding die surface S2 is taken as angle θ2.

[0294] More preferably, the range of θ2 is 0 degrees ≤ θ2-θ1 < 10 degrees, even more preferably 0 degrees ≤ θ2-θ1 < 5 degrees, and even more preferably θ2-θ1 = 0 degrees.

[0295] 2. Angular variation based on the difference in linear expansion coefficients

[0296] Since materials A and B of the present invention contain carbon fiber and glass fiber respectively, the coefficients of linear expansion of materials A and B are different. When the coefficient of linear expansion of material A is Xa, the coefficient of linear expansion of material B is Xb, and all other conditions except fiber type are the same (VfA = VfB, the types of thermoplastic resins M1 and M2 are the same, etc.), Xa / Xb < 1.

[0297] When materials A and B have different coefficients of linear expansion, and the molded body is formed by stacking materials A and B into a wave shape, the layer with the larger coefficient of linear expansion stretches the layer with the smaller coefficient of linear expansion. Specifically, when Xa / Xb < 1, material B stretches material A; therefore, for example, in... Figure 3 , Figure 6 In this process, from the moment the molded body is formed, over time, the wavy end of the molded body warps downwards towards the paper surface. As a result, the angle formed by the sidewall and the connecting wall on one side of the material B present on the surface changes (sometimes referred to as angle change) both immediately after the molded body is formed and after a period of time. In order to make the angle θ1 of the molded body the target angle, it is preferable to predict in advance the degree of angle change, bend the desired angle change as the angle θ2-θ1 in advance, and then perform stamping.

[0298] 3. Angles θ1, θ2, linear expansion coefficients Xa, Xb

[0299] When the linear expansion coefficient of material A is set to Xa and the linear expansion coefficient of material B is set to Xb, the inventors successfully predicted the angle of change of angle θ2-θ1. That is, Xa, Xb, θ1 and θ2 preferably satisfy the following equations (1) and (2).

[0300] Equation (1) 0.01≤Xa / Xb<1

[0301] Formula (2) 0≤(θ2-θ1)÷(Xa / Xb)<1.0×10 3

[0302] The upper limit of Equation (2) is more preferably less than 65, more preferably less than 15, and even more preferably less than 10.

[0303] 4. Flatness Fc of the forming mold cavity 4.1

[0305] The flatness Fc of the present invention is defined by the following steps 1' to 5'.

[0306] (Step 1') Observe the mold cavity with the mold in contact with material B as the lower mold.

[0307] (Step 2) Observe the cross-section of the forming mold cavity with a wave shape, and cut out the observation range of the forming mold cavity with a length Lyc of 40cm in the wave direction.

[0308] (Step 3') Focus on the forming mold surface used to form the lower wall.

[0309] (Step 4') Draw two parallel ideal straight lines with the required minimum width, in a manner that includes all the forming mold surfaces used to form the lower wall.

[0310] (Step 5') Define the distance between ideal straight lines as flatness Fc.

[0311] use Figure 12 Explain steps 1' to 5'.

[0312] Figure 12 The mold cavity is observed with the forming mold MB, which is in contact with material B, serving as the lower mold. Figure 12 The Y-axis direction is the wave direction. Observe the cross-section of the forming mold cavity with a wave shape, cutting the observation area of ​​the forming mold cavity with a wave length (Lyc) reaching 40cm. The forming mold surface used to form the lower wall is... Figure 12 1201.2 parallel ideal straight lines Figure 12 Example 1202. Two parallel ideal lines (1202) are drawn in such a way that the interval between them is minimized.

[0313] When Fc varies depending on the location of the cut of the length Lyc of the wave direction, it is preferable to design Fc in a way that satisfies Fa < Fc and Equation (3) at point 1. 4.2

[0315] The flatness Fc of the forming die cavity used for compression molding preferably satisfies Fa < Fc. Fa < Fc means that the molded body is closer to the plane than the forming die cavity.

[0316] When materials A and B have different coefficients of linear expansion, and when materials A and B are stacked to form a wave-shaped molded body, the layer with the larger coefficient of linear expansion stretches the layer with the smaller coefficient of linear expansion. Specifically, when Xa / Xb < 1, material B stretches material A. Therefore, for example, in... Figure 3 , Figure 6 In the process, after the molded body is first formed, it warps downwards towards the paper surface over time (at the end of the molded body in the wavy direction). As a result, the angle formed by the sidewall and the connecting wall on one side of the surface where material B exists changes after the molded body is formed and after a period of time, causing an angle change. In order to make the flatness Fa of the molded body within the target range, it is preferable to predict the degree of flatness change in advance, set the amount of flatness change as (Fc-Fa) in advance, and then bend and stamp the body. More specifically, it is more preferable to satisfy the following equations (1) and (3).

[0317] Equation (1) 0.01≤Xa / Xb<1

[0318] Formula (3) 0≤|Fc-Fa| / h÷(Xa / Xb)<1.0×103

[0319] The upper limit of equation (3) is more preferably less than 5, further preferably less than 4, even more preferably less than 3, and most preferably less than 2.

[0320] 5. Temperature ta of forming mold MA, temperature tb of forming mold MB, coefficients of linear expansion Xa and Xb

[0321] When the linear expansion coefficient of material A is set to Xa and the linear expansion coefficient of material B is set to Xb, the relationship between the temperature ta of forming mold MA and the temperature tb of forming mold MB preferably satisfies the following equations (1) and (4).

[0322] Equation (1) 0.01≤Xa / Xb<1

[0323] Formula (4) 0<|ta-tb|÷(Xa / Xb)<5000

[0324] The preferred upper limit of formula (4) is 200 or less, more preferably 100 or less, and even more preferably 50 or less. On the other hand, the preferred lower limit of formula (4) is 30 or more.

[0325] Example

[0326] The present invention will be specifically described below using examples, but the present invention is not limited to these examples.

[0327] 1. Materials

[0328] Carbon fiber

[0329] Teijin Corporation's carbon fiber "Tennax" (registered trademark) STS40-24K(EP) (average fiber diameter 7μm, fineness 1600tex, density 1.78g / cm³) 3 )

[0330] · Fiberglass

[0331] Nippon Electric Glass Co., Ltd. manufactures EX 2500 glass fiber (average fiber diameter 15μm, fiber width 9mm).

[0332] Thermoplastic resin MA

[0333] Polyamide 6 (manufactured by Unichica Co., Ltd., A1030, sometimes simply referred to as PA6).

[0334] Thermoplastic resin MB

[0335] Polyamide 6 (manufactured by Unichica Co., Ltd., A1030, sometimes simply referred to as PA6).

[0336] 2. Material determination

[0337] The values ​​in this embodiment are obtained using the following method.

[0338] (1) Determination of the fiber volume ratio (VfA, VfB) in the material

[0339] Cut a 100mm×100mm sample from material A (or material B), and heat the sample in an electric furnace (Yamato Science Co., Ltd. FP410) at 500℃ for 1 hour under a nitrogen atmosphere to burn off the organic matter such as the matrix resin.

[0340] The weights of the reinforcing fibers and thermoplastic resin were calculated by weighing the samples before and after burning. Then, the volume ratio of the reinforcing fibers was calculated using the specific gravity of each component.

[0341] Fiber volume ratio (VfA) = 100 × carbon fiber volume / (carbon fiber volume + thermoplastic resin volume of material A) Equation (c)

[0342] Fiber volume ratio (VfB) = 100 × glass fiber volume / (glass fiber volume + thermoplastic resin volume of material B) (d)

[0343] (2) Coefficient of linear expansion of the material

[0344] As a pretreatment, after the test pieces of materials A and B were vacuum dried at 110℃ for 24 hours, the linear expansion coefficient in the direction of the wave direction when the molded body was formed was randomly measured at 10 points under the following measurement conditions, and the average was calculated.

[0345] Test piece shape: 2.5mm × 5mm × 5mm

[0346] Testing model: TMA / SS7100 (manufactured by Semantec Co., Ltd.)

[0347] Heating rate: 5℃ / min

[0348] Test load: compressive load 49mN

[0349] Probe diameter: 2.9mm

[0350] Measurement atmosphere: Nitrogen atmosphere (100 ml / min)

[0351] Test temperature range: 25~200℃

[0352] 3. Cross-sectional observation

[0353] Observe the cross-section of the molded body and the mold cavity from the direction in which the wave shape can be observed. More specifically, from the direction relative to the wave direction ( Figure 1 , Figure 4The direction perpendicular to the Y-axis ( Figure 1 , Figure 4 The observation is performed along the X-axis direction, and in a direction from which the wave shape can be observed. This is also relative to the plate thickness direction. Figure 1 , Figure 4 The direction perpendicular to the Z-axis. In other words, the wave shape is observed in a direction perpendicular to both the wave direction and the plate thickness direction.

[0354] (1) Flatness Fa of the shaped body

[0355] Determine the flatness Fa in the following order.

[0356] (Step 1) The body is statically shaped with the material B present on the surface as the bottom.

[0357] (Step 2) Observe the cross-section of the shaped object in a way that the cross-section looks like a wave, and cut the observation range of the shaped object with a length Ly of 40cm in the wave direction.

[0358] (Step 3) Focus on the bottom surface of the lower wall formed by the connecting wall.

[0359] (Step 4) Two parallel ideal lines were drawn with the minimum necessary width, in a manner that includes the entire bottom surface of the lower wall.

[0360] (Step 5) Set the distance between the ideal straight lines as flatness Fa.

[0361] (2) Flatness Fc of the forming mold cavity

[0362] Determine the flatness Fc in the following order.

[0363] (Step 1') Observe the mold cavity with the forming mold MB in contact with material B as the lower mold.

[0364] (Step 2) Observe the cross-section of the forming mold cavity with a wave shape, and cut the observation range of the forming mold cavity with a wave length Lyc of 40cm.

[0365] (Step 3') Focus on the forming mold surface used to form the lower wall.

[0366] (Step 4') Two parallel ideal straight lines are drawn with the required minimum width in a manner that includes all the forming mold surfaces used to form the lower wall.

[0367] (Step 5') Set the distance between the ideal straight lines as the flatness Fc.

[0368] (3) Angle θ1

[0369] Observe the cross-section of the wavy shaped body, measure all the angles formed by the sidewall and the connecting wall on one side of material B that exists on the surface, and take the smallest angle as angle θ1.

[0370] (4) Angle θ2

[0371] When the forming mold MB is viewed in cross section, the angle θ2 formed by the forming mold surface S1 used to form the connecting wall and the forming mold surface S2 used to form the side wall is designed according to each embodiment and comparative example.

[0372] [Example 1]

[0373] 1. Preparation of Material A

[0374] As the carbon fiber, Toho Tenax Co., Ltd.'s "Tenax" (registered trademark) STS40-24K carbon fiber (average fiber diameter 7μm, single fiber count 24,000) was used, cut to a fiber length of 20mm. As the resin, Unichica Co., Ltd.'s Nylon 6 resin A1030 was used. Based on the method described in US Patent No. 8,946,342, a composite material of two-dimensionally randomly oriented carbon fiber and Nylon 6 resin was prepared. The obtained composite material was heated at 2.0 MPa for 5 minutes in a pressing apparatus heated to 260°C to obtain a flat plate-shaped material with an average thickness of 2.5mm and dimensions of 475mm × 350mm.

[0375] Analysis of the carbon fiber contained in the flat plate material showed that the carbon fiber volume fraction (Vf) was 35%, the fiber length was a certain length, and the weight-average fiber length was 20 mm.

[0376] 1.2 Preparation of Material B

[0377] Using Nippon Electric Glass Co., Ltd.'s EX 2500 glass fiber (average fiber diameter 15 μm, fiber width 9 mm) as the glass fiber and Union Chika Co., Ltd.'s Nylon 6 resin A1030 as the resin, a composite material of two-dimensionally randomly oriented glass fiber and Nylon 6 resin was prepared based on the method described in US Patent No. 8946342. The obtained composite material was heated at 2.0 MPa for 5 minutes in a pressing apparatus heated to 260°C to obtain a flat plate-shaped material with an average thickness of 0.7 mm and dimensions of 475 mm × 350 mm. Analysis of the glass fiber content in the material showed that the glass fiber volume fraction (Vf) was 45%, the fiber length was constant, and the weight-average fiber length was 20 mm.

[0378] The coefficient of linear expansion of material B along the machine direction (MD) is 1.1 × 10⁻⁶. -5The linear expansion coefficient in the TD direction (transvese direcction) is 1.8 × 10⁻⁶. -5 However, because the TD direction is aligned with the wave direction, the linear expansion coefficient Xb in Example 1 is 1.8 × 10⁻⁶. -5 .

[0379] 2. Preparation of forming mold

[0380] Prepared for making Figure 11 The forming mold shown is for the molded body. The length of the molded body in the Y-axis direction is 40cm, which is denoted as Ly.

[0381] Here, the flatness Fc is set to 11mm, the angle θ2 is set to 103 degrees (the angles formed by S1 and S2 are all the same), the temperature ta of the forming mold MA (upper mold) is set to 150℃, and the temperature tb of the forming mold MB (lower mold) is set to 150℃.

[0382] 3. Cold pressing

[0383] After drying materials A and B in a 120°C hot air dryer for 4 hours, they are stacked in the order of materials A / B and heated to 290°C by an infrared heater.

[0384] Then, the material is placed in such a way that material B comes into contact with the forming mold MB. At this time, the 475mm direction of the 475mm × 350mm material (flat plate shape) is placed as the wavy direction.

[0385] The upper mold is lowered, and pressure is applied for 1 minute at a pressing pressure of 20 MPa (the time from the start of pressing to reaching 20 MPa is 1 second), while simultaneously pressing materials A and B to create a cold-pressed body (400mm × 350mm: wavy direction). Figure 11 (Y-axis direction) × direction orthogonal to the wave direction ( Figure 11 (X-axis direction)).

[0386] The molded body is 1 hour after cold pressing. Figure 11 The shape shown is a wave-shaped molded body. The height h of the sidewalls of the molded body is 12 mm, the length of the upper wall is 23 mm, and the length of the lower wall is 25 mm. The upper and lower walls are connecting walls, and the upper and lower walls are defined and their lengths are measured by observing the material B as the lower side.

[0387] The results are shown in Table 1. The flatness Fa of the molded body is extremely high, at 0.1 mm, and the warpage is minimal. It should be noted that the warpage (direction of warpage) is downward convexity when material B is placed on the table in contact with it. (For example, ...) Figure 10 (Depicted as bulging downwards).

[0388] In addition, the longer the length of the wave direction of the shaped body, the more significant the warping problem becomes.

[0389] [Example 2]

[0390] The material B is rotated 90 degrees relative to Example 1, with the MD direction used as the wave direction and layered. Therefore, the coefficient of linear expansion Xb in Example 2 is 1.1 × 10⁻⁶. -5 Otherwise, the molded articles were made in the same manner as in Example 1. The results are shown in Table 1.

[0391] [Examples 3-5]

[0392] Except that the thickness lb of material B is set to 1.4 mm, 1.6 mm, or 2.0 mm, the molded body is made in the same manner as in Example 1. The results are shown in Table 1. The warping condition (direction of warping) is such that when material B is placed on a table in contact with the table, it bulges upward (not shown).

[0393] [Examples 6-8]

[0394] The flatness Fc of the molding die cavity was set to 0 mm, the angle θ2 was set to 100 degrees, and the molding die temperature was set as shown in Tables 1 and 2. Otherwise, the molded body was manufactured in the same manner as in Example 5. The results are shown in Tables 1 and 2.

[0395] It should be noted that in Examples 6 and 7, it was difficult to maintain the temperature difference of the molding die for mass production. Although 2 to 3 molded bodies could be manufactured, further research is needed when manufacturing more than 100 molded bodies. In addition, the molding die temperature in Example 8 was low, so the molded body could not be formed into the target shape, and some surface defects were visible on the molded body. Furthermore, the material cooled rapidly, thus reducing the transferability of the molding die.

[0396] [Example 9]

[0397] Except for designing the shape of the molding die cavity and the molding die temperature as shown in Table 2, the molded body was manufactured in the same manner as in Example 5. The results are shown in Table 2.

[0398] [Examples 10 and 11]

[0399] Except for changing the fiber volume ratio of glass fiber in material B as shown in Table 1, the molded articles were prepared in the same manner as in Example 1. The results are shown in Table 2.

[0400] [Comparative Example 1]

[0401] The molded body was fabricated in the same manner as in Example 5, with the angle θ2 of the mold cavity set to 100 degrees and the flatness set to 0 (mm). The results are shown in Table 2.

[0402] [Example 12]

[0403] Except that the thickness of material A is set to 3.6 mm and material A is used only, without material B, the molded body is made in the same manner as in Example 1, thereby preparing the reference molded body P1.

[0404] Except that the thickness 1a of material A is set to 2.6 mm and the thickness 1b of material B is set to 1.0 mm, the molded body P2 is manufactured in the same manner as in Example 1.

[0405] Drop hammer tests were conducted using two molded bodies. The test conditions were as follows: the hammer mass was 16 kg, and the height was adjusted to apply impacts of 135 J, 145 J, 155 J, and 165 J. The following evaluations were performed. The results are shown in Table 3.

[0406] Perfect: No cracks (in-plane cracks) were observed on the surface opposite to the side where the hammer struck.

[0407] Excellent: Cracks less than 10mm appear on the surface opposite to the impact surface of the hammer (in-plane cracking).

[0408] Good: Cracks (in-plane cracking) exceeding 10mm are generated on the surface opposite to the impact surface of the hammer. Fracture (thickness-direction cracking) converges to less than half the thickness of the plate.

[0409] Undesirable: Cracks (in-plane cracking) exceeding 10mm are generated on the surface opposite to the impact surface of the cone, and the fracture (thickness-direction cracking) is more than half the thickness of the plate.

[0410] [Table 1]

[0411]

[0412] [Table 2]

[0413]

[0414] [Table 3]

[0415]

[0416] [Comparative Example 2]

[0417] As material B, the molded articles were prepared in the same manner as in Example 1, except that sheet molding compound (SMC) was used. The results are shown in Table 4.

[0418] As SMC, it is an SMC containing glass fibers in a vinyl ester resin (thermosetting resin) as the matrix.

[0419] [Comparative Example 3]

[0420] Except that iron was used as material B, the molded body was made in the same manner as in Example 1. The results are shown in Table 4.

[0421] [Table 4]

[0422]

[0423] The molded bodies of Comparative Examples 2 and 3 showed less warping. However, in Comparative Example 3, problems such as iron peeling off from material layer A or iron cracking occurred after molding.

[0424] Industrial utilization potential

[0425] The molded articles of the present invention, and the molded articles obtained therefrom, can be used in various structural components, such as structural components of automobiles, and in all parts of various electrical products, machinery frames, housings, etc., where impact absorption is desired. They are particularly preferred for use as automotive components.

[0426] Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.

[0427] This application is based on Japanese Patent Application No. 2020-184217, filed on November 4, 2020, the contents of which are incorporated herein by reference.

Claims

1. A method for manufacturing a shaped article, characterized in that, Using forming molds MA and MB, which are a pair of male and female forming dies, material A is brought into contact with forming mold MA and material B is brought into contact with forming mold MB, and compression forming is performed to manufacture a shaped body. Material A comprises carbon fiber and thermoplastic resin M1, and material B comprises glass fiber and thermoplastic resin M2. The shaped body has a pair of sidewalls and a connecting wall connecting the sidewalls. The cross-section of the shaped body has a wavy shape. The flatness Fa of the molded body is related to the height h of the sidewalls as follows: 0 ≤ Fa / h < 1.

3. The flatness Fa is defined through the following steps: Step 1: The body is statically shaped with the material B present on the surface as the lower side. Step 2: Observe the cross-section of the shaped object so that it appears wavy, and cut out the observation area of ​​the shaped object with a wavy length Ly of 40cm. Step 3, focus on the bottom surface of the lower wall formed by the connecting wall. Step 4: Draw two parallel, ideal straight lines with the minimum required width, covering the entire bottom surface of the lower wall. Step 5: Define the distance between the two parallel ideal lines as flatness Fa.

2. The method for manufacturing the molded article as described in claim 1, characterized in that, The cross-section of the shaped body has multiple wave shapes, and the length of the wave direction is more than 1m.

3. The method for manufacturing the molded article as described in claim 1, characterized in that, The shaped body has a pair of sidewalls and a connecting wall connecting the sidewalls. The angle θ1 formed by the sidewall and the connecting wall on the side of the shaped body where material B exists on the surface layer satisfies 90 degrees ≤ θ1 < 160 degrees.

4. The method for manufacturing the molded article as described in claim 3, characterized in that, The forming die MB has a forming die surface S1 for forming the connecting wall and a forming die surface S2 for forming the side wall, and the angle θ2 formed by S1 and S2 satisfies θ1 < θ2.

5. The method for manufacturing the molded article as described in claim 4, characterized in that, When the coefficient of linear expansion of material A is set as Xa and the coefficient of linear expansion of material B is set as Xb, Xa, Xb, θ1 and θ2 satisfy the following equations (1) and (2). Equation (1) 0.01≤Xa / Xb<1 Equation (2) 0≤(θ2-θ1)÷(Xa / Xb)<1.0×10 3 in, The coefficient of linear expansion Xa of material A refers to the coefficient of linear expansion of the material in the direction of the wave when it has become a shaped body. The linear expansion coefficient Xb of material B refers to the linear expansion coefficient of the material in the direction of the wave when it has become a shaped body.

6. The method for manufacturing a molded article as described in any one of claims 1 to 5, characterized in that, The flatness Fc of the forming mold cavity used in compression molding satisfies Fa≤Fc.

7. The method for manufacturing a molded article as described in claim 6, characterized in that, When the coefficient of linear expansion of material A is set as Xa and the coefficient of linear expansion of material B is set as Xb, the following equations (1) and (3) are satisfied. Equation (1) 0.01≤Xa / Xb<1 Equation (3) 0≤|Fc-Fa| / h÷(Xa / Xb)<1.0×10 3 in, The coefficient of linear expansion Xa of material A refers to the coefficient of linear expansion of the material in the direction of the wave when it has become a shaped body. The linear expansion coefficient Xb of material B refers to the linear expansion coefficient of the material in the direction of the wave when it has become a shaped body.

8. The method for manufacturing a molded article as described in any one of claims 1 to 5, characterized in that, When the coefficient of linear expansion of material A is set as Xa and the coefficient of linear expansion of material B is set as Xb, the following equations (1) and (4) are satisfied. Equation (1) 0.01≤Xa / Xb<1 Formula (4) 0<|ta-tb|÷(Xa / Xb)<5000 Xa: Coefficient of linear expansion of material A Xb: Coefficient of linear expansion of material B ta: Temperature of the forming mold MA tb: Temperature of the forming mold MB in, The coefficient of linear expansion Xa of material A refers to the coefficient of linear expansion of the material in the direction of the wave when it has become a shaped body. The linear expansion coefficient Xb of material B refers to the linear expansion coefficient of the material in the direction of the wave when it has become a shaped body.

9. The method for manufacturing a molded article as described in any one of claims 1 to 5, characterized in that, The forming mold MA is the upper mold, and the forming mold MB is the lower mold.

10. The method for manufacturing a molded article as described in any one of claims 1 to 5, characterized in that, The molded body is an impact absorber, and material A is the side subjected to impact.

11. The method for manufacturing a molded article as described in any one of claims 1 to 5, characterized in that, Material A has a thickness la of 0.5 mm or more and less than 5.0 mm, and material B has a thickness lb of 0.5 mm or more and less than 3.0 mm. 1.3 ≤ la / lb ≤ 3.6 or 0.1 <lb / la<0.6。 12. The method for manufacturing a molded article as described in any one of claims 1 to 5, characterized in that, When the coefficient of linear expansion of material A is set as Xa and the coefficient of linear expansion of material B is set as Xb, the relationship between the fiber volume ratio VfA of material A and the fiber volume ratio VfB of material B satisfies the following equations (1) and (5). Equation (1) 0.01≤Xa / Xb<1 Equation (5) 0.3≤VfA / VfB≤3.0 in, The coefficient of linear expansion Xa of material A refers to the coefficient of linear expansion of the material in the direction of the wave when it has become a shaped body. The linear expansion coefficient Xb of material B refers to the linear expansion coefficient of the material in the direction of the wave when it has become a shaped body.

13. The method for manufacturing a molded article as described in any one of claims 1 to 5, characterized in that, Ribs are present between the connecting wall and the side wall.

14. The method for manufacturing a molded article as described in any one of claims 1 to 5, characterized in that, Material C lies between material A and material B. The linear expansion coefficients Xa of material A, Xb of material B, and Xc of material C are related by the following condition: Xa < Xc < Xb. in, The coefficient of linear expansion Xa of material A refers to the coefficient of linear expansion of the material in the direction of the wave when it has become a shaped body. The coefficient of linear expansion Xb of material B refers to the coefficient of linear expansion of the material in the direction of the wave when it has become a shaped body. The coefficient of linear expansion Xc of material C refers to the coefficient of linear expansion of the material in the direction of the wave when it has become a shaped body.

15. The method for manufacturing a molded article as described in any one of claims 1 to 5, characterized in that, A linear expansion modifier is incorporated so that, when the coefficient of linear expansion of material A is set as Xa and the coefficient of linear expansion of material B is set as Xb, 0.8 ≤ Xa / Xb ≤ 1. in, The coefficient of linear expansion Xa of material A refers to the coefficient of linear expansion of the material in the direction of the wave when it has become a shaped body. The linear expansion coefficient Xb of material B refers to the linear expansion coefficient of the material in the direction of the wave when it has become a shaped body.

16. The method for manufacturing a molded article as described in any one of claims 1 to 5, characterized in that, By using a thermoplastic resin M2 with a smaller coefficient of linear expansion than thermoplastic resin M1, it is adjusted so that when the coefficient of linear expansion of material A is set as Xa and the coefficient of linear expansion of material B is set as Xb, 0.8 ≤ Xa / Xb ≤ 1. in, The coefficient of linear expansion Xa of material A refers to the coefficient of linear expansion of the material in the direction of the wave when it has become a shaped body. The linear expansion coefficient Xb of material B refers to the linear expansion coefficient of the material in the direction of the wave when it has become a shaped body.

17. The method for manufacturing a molded article as described in any one of claims 1 to 5, characterized in that, The temperature ta of forming mold MA and the temperature tb of forming mold MB are below room temperature +10℃.

18. The method for manufacturing a molded article as described in any one of claims 1 to 5, characterized in that, Material A and material B are stacked and then compressed and formed.

19. The method for manufacturing a molded article as described in claim 18, characterized in that, Material A and Material B are flat.

20. The method for manufacturing a molded article as described in claim 18, characterized in that, When materials A and B are formed into a molded body, they form material layer A and material layer B, respectively.

21. A method for manufacturing a joint, characterized in that, Under the condition that the angular stress θ1 of the molded body is reduced and the flatness Fa' of the molded body after stress deformation is related to the height h of the sidewall as 0 ≤ Fa' / h < 0.1, the molded bodies are joined to manufacture a joined body. The shaped body is manufactured by the manufacturing method according to any one of claims 1 to 5, the shaped body having a pair of sidewalls and a connecting wall connecting the sidewalls, and the material B is present on one side of the surface layer at an angle θ1 formed by the sidewalls and the connecting wall satisfying 90 degrees ≤ θ1 < 160 degrees.

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