Resin part and insert molded article
Patent Information
- Application Number
- PCT/JP2026/011426
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-03-28
- Filing Date
- 2026-03-23
- Publication Date
- 2026-10-01
Smart Images
Figure JP2026011426_01102026_PF_FP_ABST
Abstract
Description
Resin component and insert-molded article
[0001] The present disclosure relates to a resin component and an insert-molded article.
[0002] An insert-molded article is a molded article produced by placing an insert such as a metal component in a mold for molding, and combining a resin material and a metal material. Since a component having a desired structure can be produced through a simple process, insert-molded articles are used in various components including automobile components. Patent Document 1 discloses an insert molding method in which an insert component that is a metal conductor is set in a molding die, and a thermoplastic resin is injected for integral molding. Patent Document 2 discloses a method for manufacturing an automobile seat back frame, which comprises: shaping a fiber-reinforced composite material into the shape of a seat back frame body by cold press molding, and welding a metal plate to the seat back frame body by insert molding during shaping.
[0003] International Publication No. 2015 / 29482, International Publication No. 2013 / 21482
[0004] For example, as an impact detection sensor, an insert-molded article in which a metal component is disposed on a resin component can be used. However, in such an insert-molded article where a metal component is disposed on a resin component, warpage caused by shrinkage of the resin component during molding creates a gap between the metal component and the resin component, which may cause the metal component to lift off from the resin component. Lifting of the metal component may lead to dimensional deviation of the molded article or deterioration of the component performance.
[0005] The present disclosure relates to a resin component that has a thin-walled portion and is less prone to warpage, and an insert-molded article that includes the resin component and a metal component and is less prone to warpage.
[0006] A resin part according to one embodiment of the present disclosure is a resin part having, when observed in cross-section, two or more thickness-shifting portions and a thin-walled portion thinner than the thickness-shifting portions between the thickness-shifting portions, wherein the thickness-shifting portions form a convex portion on one side of the resin part, the resin part is made of a fiber-reinforced composite material including reinforcing fibers and a thermoplastic resin, the thickness-shifting portion has a first resin layer and a second resin layer positioned on the side of the first resin layer, and satisfies the following equations: (1) Vf1 × 0.9 < Vf2 < Vf1 × 1.1, (2) Lw1 > Lw2, (3) 1 mm < Lw2 ≤ W, (4) t2 < 7 mm. However, Vf1: fiber volume ratio of the first resin layer Vf2: fiber volume ratio of the second resin layer Lw1: weight-average fiber length of reinforcing fibers contained in the first resin layer LW2: weight-average fiber length of reinforcing fibers contained in the second resin layer t2: thickness of the resin part in the thin-walled section W: length of one side of the convex portion when observed in cross-section
[0007] An insert molded body according to one embodiment of the present disclosure is an insert molded body having a resin part and a metal part, wherein at least a portion of the metal part is arranged on the outer surface of the resin part along the uneven thickness portion or the thin thickness portion, the metal part has a deflection portion whose direction of extension on the outer surface is changed, and the resin part and the metal part are fixed to each other at the deflection portion.
[0008] The resin component of this disclosure is less prone to warping despite having a thin-walled portion, and the insert molded body having the resin component and the metal component is less prone to warping and lifting of the metal component.
[0009] Figure 1 is a plan view showing an insert molded body according to the first embodiment of this disclosure. Figure 2 is a cross-sectional view taken along the line A-A in Figure 1. Figure 3 is a cross-sectional view taken along the line B-B in Figure 1. Figure 4A is a cross-sectional view showing the warping when the first resin layer and the second resin layer are made of the same type of resin. The cross-section is observed from the direction of the length of the groove formed by the uneven thickness portion and the thin-walled portion. Figure 4B is a cross-sectional view showing the warping when the fiber volume ratio Vf2 of the second resin layer is significantly smaller than the fiber volume ratio Vf1 of the first resin layer. The cross-section is observed from a direction perpendicular to the length of the groove formed by the uneven thickness portion and the thin-walled portion. Figure 5 is a cross-sectional view showing a part of a resin part according to the first embodiment of this disclosure. Figure 6 is a cross-sectional view of a mold for manufacturing an insert molded body according to one embodiment of this disclosure. Figure 7 is a cross-sectional view showing the manufacturing process of an insert molded body according to one embodiment of this disclosure. Figure 8 is a cross-sectional view showing the manufacturing process of an insert molded body according to one embodiment of this disclosure. Figure 9 is a cross-sectional view showing the manufacturing process of an insert molded body according to one embodiment of this disclosure. Figure 10 is a cross-sectional view showing an insert molded body according to an example.
[0010] First, embodiments of the present disclosure will be listed and described. A resin part according to one embodiment of the present disclosure is a resin part having, when observed in cross-section, two or more thickness-shifting portions and a thin-walled portion between the thickness-shifting portions that is thinner than the thickness-shifting portions, wherein the thickness-shifting portions form a convex portion on one side of the resin part, the resin part is made of a fiber-reinforced composite material including reinforcing fibers and a thermoplastic resin, the thickness-shifting portion has a first resin layer and a second resin layer positioned on the side of the first resin layer that is on the side of the first resin layer, and satisfies the following equations: (1) Vf1 × 0.9 < Vf2 < Vf1 × 1.1, (2) Lw1 > Lw2, (3) 1 mm < Lw2 ≤ W, (4) t2 < 7 mm. However, Vf1: fiber volume ratio of the first resin layer Vf2: fiber volume ratio of the second resin layer Lw1: weight-average fiber length of reinforcing fibers contained in the first resin layer LW2: weight-average fiber length of reinforcing fibers contained in the second resin layer t2: thickness of the resin part in the thin-walled section W: length of one side of the convex portion when observed in cross-section
[0011] When manufacturing an insert molded body in which a metal part is placed on a resin part, the resin part may shrink during molding, causing it to warp and create a gap between the metal part and the resin part, which can cause the metal part to lift away from the resin part. In the resin part according to this embodiment, the thickness-variant portion has a first resin layer and a second resin layer, and the fiber volume ratio of each resin layer and the weight-average fiber length of the reinforcing fibers contained in each resin layer are specified. This makes it possible to reduce the warping of the resin part in the longitudinal direction of the groove formed by the thickness-variant portion and the thin-walled portion, and in the direction perpendicular to the groove. If the thin-walled portion is thick and its thickness is 7 mm or more, the problem of warping does not occur in the first place, so there is little significance in adopting the configuration of the present invention. This is because when the thin-walled portion is 7 mm or more, the thickness rigidity of the thin-walled portion increases, which counteracts the warping stress.
[0012] (2) In (1) above, the second resin layer may be manufactured using crushed material obtained by crushing a fiber-reinforced composite material containing reinforcing fibers and thermoplastic resin.
[0013] The resin parts according to this embodiment are manufactured using crushed material obtained by crushing a fiber-reinforced composite material containing reinforcing fibers and thermoplastic resin. The crushed material obtained by crushing the fiber-reinforced composite material includes materials such as used fiber-reinforced plastics and refers to recyclable materials. In other words, by manufacturing the resin parts according to this embodiment using crushed material obtained by crushing the fiber-reinforced composite material, the environmental burden can be reduced.
[0014] (3) In (1) above, 0.5 < t2 / t1 < 0.9 is also acceptable, where t1 is the thickness of the resin part in the uneven thickness portion.
[0015] According to the resin part of this embodiment, the length relationship between the unevenly thickened portion and the thickened portion is within a certain range, which suppresses warping during molding and effectively reduces lifting.
[0016] The resin parts according to this embodiment can suppress warping during molding.
[0017] (4) An insert molded body according to one embodiment of the present disclosure comprises the resin part described in (1) above and a metal part, wherein at least a portion of the metal part is arranged on the outer surface of the resin part along the uneven thickness portion or the thin thickness portion, the metal part has a deflection portion whose direction of extension on the outer surface is changed, and the resin part and the metal part may be fixed to each other at the deflection portion.
[0018] The insert molded body according to this embodiment can effectively reduce lifting.
[0019] (5) In (4) above, when the direction perpendicular to the outer surface of the resin part is defined as the thickness direction, the difference in thickness between the unevenly thickened portion and the thinned portion may be greater than or equal to the thickness of the metal part.
[0020] Hereinafter, resin parts and insert molded articles according to one embodiment of the present disclosure will be described with reference to the drawings, but the present invention is not limited to these examples. The dimensions and positions of each component in the drawings are schematic and are not intended to limit the dimensions and positions of components in the actual product.
[0021] [Insert Molded Body] Figure 1 is a plan view showing an insert molded body 1 according to the first embodiment of the present disclosure. The insert molded body 1 according to this embodiment can be used, for example, as an impact detection sensor placed on the bottom of a vehicle. As shown in Figure 1, the insert molded body 1 includes a resin part 10 and a metal part 20, the metal part 20 being placed on the outer surface of the resin part 10. Figure 2 is a cross-sectional view taken along the line A-A in Figure 1. Figure 3 is a cross-sectional view taken along the line B-B in Figure 1.
[0022] (Resin part) The resin part 10 has a substantially flat shape. As shown in Figure 2, when observed in cross-section, the resin part 10 has two or more uneven thickness portions 11 and thin-walled portions 12 that are thinner than the uneven thickness portions 11 between them. One side surface of the resin part 10 (the top surface in Figure 2) is provided with a convex portion corresponding to the uneven thickness portion 11, and the other main surface (the bottom surface in Figure 2) is flat. In this disclosure, the uneven thickness portion 11 refers to a portion of the resin part 10 that is uneven in thickness relative to the whole, and the uneven thickness portion 11 itself may be of uniform thickness. When a metal part 20 is placed along an uneven thickness portion 11, it is preferable that the outer surface of the uneven thickness portion 11 on which the metal part 20 is placed is flat.
[0023] The shape of the protrusion corresponding to the uneven thickness portion 11 is not particularly limited. The shape of the protrusion when observed in cross-section may be rectangular, trapezoidal, semicircular, or a combination of these. Furthermore, if the shape of the protrusion is rectangular or trapezoidal, at least one corner may be rounded. The point where the protrusion and the thin-walled portion 12 meet when observed in cross-section may have a corner or be rounded.
[0024] The resin component 10 is made of a fiber-reinforced composite material containing reinforcing fibers and thermoplastic resin. Carbon fibers, basalt fibers, and glass fibers may be used as the reinforcing fibers, and two or more of these may be used in combination.
[0025] Examples of thermoplastic resins 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, and polylactic acid resins.
[0026] Thermoplastic resins may be crystalline or amorphous resins. In the case of crystalline resins, 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 particularly suitable due to their excellent heat resistance and mechanical strength.
[0027] The thickness of the resin part 10 is not particularly limited, but is, for example, 0.5 mm to 10.0 mm, preferably 1.0 mm to 8.0 mm. The thickness of the resin part 10 here refers to the thickness of the thickest part, and more specifically, the maximum thickness of the unevenly thickened portion 11.
[0028] The thickness t1 of the resin part 10 in the uneven thickness portion 11 is not particularly limited, but is, for example, less than 10 mm, preferably 8 mm or less, and more preferably 7 mm or less. The lower limit is not particularly limited, but is, for example, 1 mm or more.
[0029] The thickness t2 of the resin part 10 in the thin-walled section 12 is less than 7 mm, preferably 5 mm or less, and more preferably 4 mm or less. There is no particular lower limit, but for example it is 1 mm or more, preferably 2 mm or more, and more preferably 2.5 mm or more. As mentioned above, when the thickness t2 is 7 mm or more, warping of the resin part is less likely to occur in the first place, and the problems of the present invention do not arise. This is because when the thin-walled section is 7 mm or more, the thickness rigidity of the thin-walled section increases, which counteracts the warping stress.
[0030] The ratio t2 / t1, which is the ratio of the thickness t2 of the resin part 10 in the thin-walled section 12 to the thickness t1 of the resin part 10 in the uneven-walled section 11, is not particularly limited, but for example, 0.5 < t2 / t1 < 0.9, preferably 0.5 < t2 / t1 < 0.8, more preferably 0.5 < t2 / t1 < 0.75, even more preferably 0.55 < t2 / t1 < 0.75, and even more preferably 0.55 < t2 / t1 < 0.7. When 0.5 < t2 / t1, the rigidity of the thin-walled section is ensured to a certain extent, thus suppressing warping. On the other hand, when t2 / t1 < 0.9, it becomes easier to create the desired shape.
[0031] (Metal part) The metal part 20 is a metal plate placed on the outer surface of the resin part 10. As shown in Figure 1, the metal part 20 is arranged in a bellows-like manner on the main surface of the resin part 10 and is configured to broadly cover the main surface of the resin part 10. At least a portion of the metal part 20 is placed on the outer surface of the resin part 10 along the thickness variation portion 11 or the thin-walled portion 12. In the insert molded body 1 of Figure 1, the metal part 20 is placed along the thickness variation portion 11 of the resin part 10, or more specifically, on the thickness variation portion 11.
[0032] As shown in Figure 1, the metal part 20 has a deflection section 23 whose direction of extension on its outer surface is changed. More specifically, the metal part 20 has a first portion 21 extending in the vertical direction of the paper (hereinafter referred to as the first in-plane direction) and a second portion 22 extending in the horizontal direction of the paper (hereinafter referred to as the second in-plane direction), and the first portion 21 and the second portion 22 are connected at the deflection section 23. In this embodiment, the rectangular area where the extended portion of the first portion 21 and the extended portion of the second portion 22 overlap can be considered as the deflection section 23.
[0033] The metal material constituting the metal part 20 is not particularly limited, and various metals or alloys can be used depending on the required properties. Examples of metal materials include copper, aluminum, iron, chromium, nickel, manganese, or alloys thereof.
[0034] The shape of the metal part 20 is not limited to a plate shape and can be changed as appropriate depending on the application and configuration. Specifically, the metal part 20 may be a metal wire having a substantially circular cross-section, or a bundle of laminated or stacked metal wires.
[0035] The thickness of the metal part 20 is not particularly limited and can be changed as appropriate depending on the application and configuration. The thickness of the metal part 20 may be, for example, 0.01 mm to 10 mm, 0.05 mm to 1.0 mm, or 0.10 mm to 0.50 mm. If the metal part 20 is a metal wire, the maximum diameter along the thickness direction in the cross-section of the metal wire is considered to be the thickness.
[0036] (Fixing of resin and metal parts) The resin part 10 and the metal part 20 may be fixed to each other at the deflection portion 23 of the metal part 20. Specifically, the insert molded body 1 may have a crimping portion 30 that fixes the resin part 10 and the metal part 20 at the deflection portion 23 of the metal part 20. Figure 3 is a cross-sectional view taken along the line B-B in Figure 1, showing how the resin part 10 and the metal part 20 are fixed to each other by the crimping portion 30. The metal part 20 has a hole at a position corresponding to the crimping portion 30. The crimping portion 30 is formed when resin material is extruded from the hole provided in the metal part 20 during compression molding. Therefore, the crimping portion 30 is made of the same resin material as the resin part 10.
[0037] Since the insert molded body 1 is manufactured by heating during molding and then cooling to room temperature, each component constituting the insert molded body 1 shrinks during cooling. In the case of an insert molded body 1 having a resin component 10 and a metal component 20, the thermal expansion coefficient of the metal component 20 is generally larger than that of the resin component 10, so the metal component 20 shrinks more than the resin component 10. In particular, in the deflection portion 23 of the metal component 20 where the direction of expansion is changed, a force is generated that causes it to shrink in a different vector during contraction. As a result, the deflection portion 23 of the metal component 20 is particularly prone to lifting away from the resin component 10.
[0038] In this embodiment, the insert molded body 1 has the resin part 10 and the metal part 20 fixed to each other by a crimping part 30 in the deflection part 23 which is prone to lifting. This makes it possible to reduce the lifting of the metal part 20.
[0039] The uneven thickness portion 11 of the resin part 10 has a first resin layer 13 and a second resin layer 14 positioned closer to the metal part 20 than the first resin layer 13. The fiber volume ratio Vf1 of the first resin layer 13 and the fiber volume ratio Vf2 of the second resin layer 14 satisfy the following relationship: Equation (1) Vf1 × 0.9 < Vf2 < Vf1 × 1.1 By having a first resin layer 13 and a second resin layer 14 that satisfy the above fiber volume ratio relationship in the uneven thickness portion 11 of the resin part 10, warping of the resin part 10 can be suppressed. The preferred range of Equation (1) is Vf1 × 0.95 < Vf2 < Vf1 × 1.05. It is more preferable that Vf1 and Vf2 are the same. When a resin part is molded using the exact same molding material for both the first resin layer 13 and the second resin layer 14 (i.e., the fiber volume ratio Vf1 of the first resin layer 13 and the fiber volume ratio Vf2 of the second resin layer 14 are the same, and the weight-average fiber length Lw1 of the first resin layer 13 and the weight-average fiber length Lw2 of the second resin layer 14 are the same), the resin part in Figure 2 will bend upwards in the left-right direction of the paper. Figure 4A shows a cross-sectional view of the resin part in this upward-convex state. Figure 4A is a cross-sectional view showing the curvature when the first resin layer 13 and the second resin layer 14 are made of the same type of resin layer. The cross-section in Figure 4A is observed from the length direction of the groove formed by the uneven thickness portion 11 and the thin-walled portion 12. On the other hand, if the fiber volume ratio Vf2 of the second resin layer 14 is made significantly lower than the fiber volume ratio Vf1 of the first resin layer 13, the warping of the resin part 10 in the direction perpendicular to the length direction of the groove formed by the uneven thickness portion 11 and the thin-walled portion 12 (the left-right direction in the plane of the paper in Figure 2) can be reduced. However, in the length direction of the groove formed by the uneven thickness portion 11 and the thin-walled portion 12 (the depth direction in the plane of the paper in Figure 2), a warp occurs that is convex downwards (see Figure 4B). Figure 4B is a cross-sectional view showing the warping when the fiber volume ratio Vf2 of the second resin layer 14 is made significantly smaller than the fiber volume ratio Vf1 of the first resin layer 13, and the cross-section is observed from a direction perpendicular to the length of the groove formed by the uneven thickness portion 11 and the thin-walled portion 12. This is because the molding shrinkage rate of the second resin layer 14 is greater than that of the first resin layer 13, and the first resin layer 13 is pulled toward the second resin layer 14, causing the resin part 10 to warp. In other words, the inventors considered that the warping elimination due to the difference between Vf1 and Vf2 was insufficient.Therefore, the present invention succeeds in reducing both the warping of the resin part 10 in the longitudinal direction of the groove formed by the unevenly thickened portion 11 and the thinned portion 12, and in the direction perpendicular thereto, by satisfying formula (2) Lw1 > Lw2 and formula (3) 1 mm < Lw2 ≤ W within the range that satisfies formula (1) Vf1 × 0.9 < Vf2 < Vf1 × 1.1.
[0040] The fiber volume ratio Vf1 of the first resin layer 13 and the fiber volume ratio Vf2 of the second resin layer 14 are, for example, 25 to 45%, preferably 30 to 40%.
[0041] The fiber volume ratio of the first resin layer 13 and the second resin layer 14 can be determined, for example, by the following method: Cut a 100 mm x 100 mm sample from the resin part 10. (i) Measure the weight of the resin part. (ii) Heat the sample in an electric furnace (FP410 manufactured by Yamato Scientific Co., Ltd.) heated to 550°C under a nitrogen atmosphere for 4 hours to burn off organic matter such as matrix resin, and measure the weight. (iii) Measure the weight of the sample consisting only of reinforcing fibers. Calculate the weight of the resin and reinforcing fibers by weighing the weights from (i) to (iii). Next, using the specific gravity of each component, calculate the volume ratio of the reinforcing fibers from the following formula (5). Fiber volume ratio = 100 × volume of reinforcing fibers / (volume of reinforcing fibers + volume of resin) (1)
[0042] The weight-average fiber length Lw1 of the reinforcing fibers contained in the first resin layer 13 of the resin part 10 is preferably 100 mm or less. When the weight-average fiber length is 100 mm or less, the warping of the thin-walled portion 12 can be reduced. The weight-average fiber length of the reinforcing fibers contained in the first resin layer 13 of the resin part 10 is preferably 50 mm or less, more preferably 30 mm or less. On the other hand, when the length of one side of the convex portion when observed in cross-section is W, it is preferable that W < Lw1. Specifically, it is preferable that it be 20 mm or more. This is to ensure the mechanical properties of the resin part.
[0043] The weight-average fiber length of the reinforcing fibers contained in the resin part 10 can be determined, for example, by the following method: Measure the fiber length of 100 fibers randomly selected from the resin part 10 to the nearest 1 mm using a caliper or the like. The fiber length of each individual reinforcing fiber is then calculated as L ｉAssuming that the measured number of fibers is j, the weight-average fiber length (Lw) can be obtained by the following formula (a).
[0044]
[0045] In this embodiment, the weight-average fiber length Lw1 of the reinforcing fibers contained in the first resin layer 13 and the weight-average fiber length Lw2 of the reinforcing fibers contained in the second resin layer 14 satisfy the following relationship. Formula (2): Lw1 > Lw2 That is, formula (2) indicates that the weight-average fiber length Lw1 of the reinforcing fibers contained in the first resin layer 13 is longer than the weight-average fiber length Lw2 of the reinforcing fibers contained in the second resin layer 14. By adjusting the weight-average fiber length of the reinforcing fibers such that the weight-average fiber length of the reinforcing fibers contained in the first resin layer 13 and the second resin layer 14 of the resin component 10 satisfies the above formula (2), the warpage of the resin component 10 can be suppressed.
[0046] Furthermore, regarding the convex portion corresponding to the uneven thickness portion 11 of the resin component 10, when W represents the length of one side surface of the convex portion when the cross-section is observed, W and Lw2 satisfy the following relationship. Formula (3): 1 mm < Lw2 ≤ W By designing the weight-average fiber length Lw2 in this manner, fibers are prevented from orienting along the surface layer in the convex portion. In other words, when reinforcing fibers orient along the surface layer within the convex portion, warpage occurs. If the weight-average fiber length Lw is 1 mm or more, it becomes easy to impart structural rigidity to the resin component itself. It should be noted that, generally, in molded articles produced by injection molding, the weight-average fiber length of reinforcing fibers is approximately 0.1 to 0.3 mm. Therefore, in order to make the weight-average fiber length Lw2 exceed 1 mm, it is preferable to produce the resin component by compression molding (press molding). By adjusting the weight-average fiber length of the reinforcing fibers such that the weight-average fiber length of the reinforcing fibers contained in the second resin layer 14 of the resin component 10 satisfies the above formula (2), or by forming the convex portion, the warpage of the resin component 10 can be further suppressed. The reason for this will be described below.
[0047] Fig. 5 is a cross-sectional view for explaining the orientation of reinforcing fibers in the first resin layer 13 and the second resin layer 14 of the present embodiment. The plurality of broken lines F in Fig. 5 are lines schematically showing the orientation and density of fibers in each region. The weight-average fiber length Lw1 of the reinforcing fibers contained in the first resin layer 13 is longer than the weight-average fiber length Lw2 of the reinforcing fibers contained in the second resin layer 14, therefore, as shown in Fig. 5, in the first resin layer 13, the reinforcing fibers are generally oriented two-dimensionally randomly in the in-plane direction. On the other hand, since the weight-average fiber length Lw2 of the reinforcing fibers contained in the second resin layer 14 is equal to or less than the length W of one side surface of the convex portion when observed in cross section, in the second resin layer 14, the reinforcing fibers are randomly oriented in any three-dimensional direction. When the reinforcing fibers are randomly oriented in three-dimensional directions in the second resin layer 14 as described above, the second resin layer 14 absorbs the influence of shrinkage of the metal component 20, making the first resin layer 13 less susceptible to the influence, whereby warpage of the resin component 10 can be suppressed.
[0048] In order to obtain the above effect, it is preferable that the weight-average fiber length Lw1 of the reinforcing fibers contained in the first resin layer 13 is longer than the length W of one side surface of the convex portion when observed in cross section. When Lw1>W, the reinforcing fibers contained in the first resin layer 13 are less likely to enter the second resin layer 14 forming the convex portion, so the reinforcing fibers are likely to be randomly oriented in three-dimensional directions in the convex portion. Here, "the length of the one side surface of the convex portion when observed in cross section" refers to the length of one side surface of the convex portion in a cross section orthogonal to the direction in which the convex portion extends, as shown in Fig. 2.
[0049] The above effect is remarkable in a range where the thickness t2 of the resin component 10 in the thin-walled portion 12 is less than 7 mm.
[0050] In the insert molded body 1 according to this disclosure, when the thickness direction is defined as the direction perpendicular to the outer surface of the resin part 10, it is preferable that the difference between the thickness t1 of the resin part 10 in the unevenly thickened portion 11 and the thickness t2 of the resin part 10 in the thin-walled portion 12 (height of the protrusion H = t1 - t2) is equal to or greater than the thickness of the metal part 20. When the difference in thickness between the unevenly thickened portion 11 and the thin-walled portion 12 is equal to or greater than the thickness of the metal part 20, the depth of the groove provided in the mold 40 to form the unevenly thickened portion 11 becomes at least twice the thickness of the metal part 20, making it easy to position the metal part 20 and easy to mold. When the metal parts 20 are laminated or stacked, the above effect can be obtained if the difference in thickness between the unevenly thickened portion 11 and the thin-walled portion 12 is equal to or greater than the thickness of the individual metal parts 20, but more preferably it is equal to or greater than the total thickness of the laminated or stacked metal parts 20.
[0051] [Method for Manufacturing an Insert Molded Body] Next, a method for manufacturing an insert molded body 1 according to one embodiment of the present disclosure will be described. Figure 6 is a diagram showing a mold 40 for manufacturing an insert molded body 1. The mold 40 consists of an upper mold 41 and a lower mold 42.
[0052] As shown in Figure 6, the lower mold 42 is provided with a groove 43 at a position corresponding to the thickness variation portion 11. In this embodiment, the insert molded body 1 is manufactured using the molding die 40, as described below. First, as shown in Figure 7, the metal material 50 that will become the metal part 20 is placed in the groove 43 of the lower mold 42 so as to fit into it. The metal material 50 typically has the same shape as the metal part 20 after molding. That is, the metal material 50 has a deflection portion 23, and the deflection portion 23 is provided with a hole for forming a crimping portion 30.
[0053] Next, as shown in Figure 8, the second molding material 60, which will form the second resin layer 14, is placed on top of the metal material 50 in the groove 43 of the lower mold 42. Next, the first molding material 70, which will form the first resin layer 13, is placed on top of the second molding material 60.
[0054] Next, as shown in Figure 9, the upper mold 41 is lowered toward the lower mold 42, and the mold 40 is heated to a temperature above the melting point or glass transition point of the thermoplastic resin (for example, 150°C), and the mold 40 is closed to perform compression molding. In this compression molding process, the second molding material 60 is molded into a shape corresponding to the groove 43 of the lower mold 42, thereby forming the uneven thickness portion 11. In addition, the second molding material is extruded from the holes provided in the deflection portion 23 of the metal material 50, forming the crimped portion 30.
[0055] Subsequently, by cooling the mold 40 to room temperature, an insert molded body 1 is obtained in which the metal part 20 and the resin part 10 are integrated. At this time, the metal part 20 and the resin part 10 are fixed to each other by the formed crimping portion 30.
[0056] [Cold Press Molding] The above molding method is a compression molding method called cold press molding, and the preferred molding method for manufacturing the resin parts of the present invention is press molding using cold press. Cold press will be described below. Cold press involves, for example, placing a first molding material and a second molding material, which have been preheated to a first predetermined temperature, into a mold set to a second predetermined temperature, and then applying pressure and cooling. Specifically, if the thermoplastic resins constituting the first molding material and the second molding material are crystalline, the first predetermined temperature is above the melting point of the thermoplastic resin, and the second predetermined temperature is below the melting point. If the thermoplastic resin is amorphous, the first predetermined temperature is above the glass transition temperature of the thermoplastic resin, and the second predetermined temperature is below the glass transition temperature. That is, the cold press molding method includes at least the following steps A-1) to A-2). Step A-1) A step of heating the first molding material and the second molding material to a temperature above the melting point of the thermoplastic resin and below the decomposition temperature of the thermoplastic resin if the thermoplastic resin is crystalline, and above the glass transition temperature and below the decomposition temperature of the thermoplastic resin if the thermoplastic resin is amorphous. Step A-2) A step of placing the first molding material and the second molding material heated in Step A-1) into a mold whose temperature is controlled to below the melting point if the thermoplastic resin is crystalline, and below the glass transition temperature if the thermoplastic resin is amorphous, and applying pressure. By performing these steps, the molding of the first molding material and the second molding material can be completed. The above steps must be performed in the order described above, but other steps may be included between each step. Other steps include, for example, a shaping step before Step A-2) in which a different shaping mold is used from the mold used in Step A-2) to pre-shape the material to the shape of the mold cavity.
[0057] [Cold Pressing and Warping] Cold pressing is more prone to warping than hot pressing. In cold pressing, the molding material is placed in the lower mold, so the molding material in contact with the surface of the lower mold cools first. This results in a difference in the cooling rate of the resin between the surface in contact with the lower mold and the surface in contact with the upper mold. As a result, the molding shrinkage of the molding material in contact with the lower mold occurs first, causing the entire resin part to be pulled by the molding material in contact with the lower mold. Therefore, a more pronounced warping problem occurs when using cold pressing, but this invention can be used to more effectively eliminate warping.
[0058] The insert molded body 1 formed in this manner has a resin part 10 and a metal part 20, and the resin part 10 has two or more unevenly thickened portions 11 and thin-walled portions 12 between the unevenly thickened portions 11 that are thinner than the unevenly thickened portions 11.
[0059] The present disclosure will be described below in accordance with the examples, but the present disclosure is not limited to these. [Materials] 1. Reinforcement fiber - Glass fiber E-glass RS240QR-483 manufactured by Nitto Boseki Co., Ltd. was prepared by attaching a sizing agent. (Sometimes abbreviated as GF). 2. Resin Polyamide 6 resin: (Manufactured by Unitika, A1030, melting point 215-220°C, thermal decomposition temperature 300°C), sometimes referred to as PA6.
[0060] [Examples 1-4, Comparative Examples 1-6, and Reference Examples 1, 2] (First Molding Material) As glass fibers, Nitto Boseki Co., Ltd.'s glass fiber E-glass RS240QR-483 was cut to a fiber length of 20 mm. Polyamide 6 resin (Unitika, A1030) was used as the resin. A composite composition of glass fibers and polyamide 6 resin in which glass fibers were oriented randomly in two dimensions was prepared based on the method described in U.S. Patent No. 8,946,342. Specifically, a breathable support that moves continuously in one direction and has a suction mechanism at the bottom was installed, and while suction was performed by the suction mechanism, the above glass fibers and polyamide 6 resin were blown onto the upper part of the breathable support with compressed air from a tapered tube positioned above the breathable support, and a composite product in which glass fibers and polyamide 6 resin were mixed was prepared. The obtained composite composition was heated in a press device heated to 250°C at 2.0 MPa for 20 minutes to prepare a first molding material with an average thickness of 4 mm. At this time, reinforcing fibers were prepared so that the weight-average fiber length Lw1 (mm) was the value shown in Table 1, and the first molding material was prepared by mixing the reinforcing fibers and thermoplastic resin fibers so that the fiber volume ratio Vf1 (%) in the first resin layer 13 was the value shown in Table 1. In Example 3, continuous fibers were used for the reinforcing fibers without cutting them.
[0061] (Second molding material) A portion of the first molding material prepared above was fed into a crushing and grinding machine and crushed into 8 mm x 8 mm squares. The crushed material was fed into a double belt press to create a flat plate-shaped molding material again, which was used as the second molding material. The second molding material can be said to be crushed material. Reinforcement fibers were prepared so that the weight-average fiber length Lw2 (mm) was the value shown in Table 1, and the reinforcement fibers and thermoplastic resin fibers were mixed to create the second molding material so that the fiber volume ratio Vf2 (%) in the second resin layer 14 was the value shown in Table 1.
[0062] An insert molded body 1 was created by cold pressing using the prepared first molding material, second molding material, and metal material 20, as shown in Figure 10. The length in the left-right direction (X direction) of Figure 10 was 200 mm, and the length in the direction perpendicular to the plane of the paper (Y direction) was 100 mm. The width w1 (mm) of the uneven thickness portion 11, the width w2 (mm) of the thin-walled portion 12, the height H (t1 - t2) (mm) of the protrusion, the length W (= w1 + 2H) (mm) of one side of the protrusion, the thickness t1 (mm) of the resin part 10 in the uneven thickness portion 11, and the thickness t2 (mm) of the resin part 10 in the thin-walled portion 12 are as shown in Table 1.
[0063] [Evaluation] (Warping amount) Using both ends in the in-plane direction perpendicular to the direction in which the protrusion extends (X direction in Figure 10) as a reference, the displacement of the central part was measured and defined as the warping amount in the X direction (mm). Using both ends in the direction in which the protrusion extends (Y direction perpendicular to the plane of the paper in Figure 10) as a reference, the displacement of the central part was measured and defined as the warping amount in the Y direction (mm). A small warping amount is preferable. Specifically, if the warping amount is smaller than the height H (t1-t2) of the protrusion or the thickness t2 of the resin part 10, the warping can be said to be minor and is preferable.
[0064] (Moldability of the molding material) The following evaluation was performed: Excellent: The shape of the protrusion can be molded without chipping. Good: Chips of 1 mm or less occur in the protrusion. Bad: Chips of more than 1 mm occur in the protrusion.
[0065] (Tensile Strength) A test specimen approximately 300 mm long and 50 mm wide was cut from the second resin layer and pulled at a speed of 200 mm / min on a tensile testing machine with a clamp distance of 200 mm, and the tensile strength at fracture was measured. Table 1 shows the relative values (tensile strength ratio) with the tensile strength of Comparative Example 1 set to 100.
[0066] The results are shown in Table 1.
[0067] The resin parts and insert molded articles of this disclosure are applicable to various parts of moving objects and industrial machinery, and can be applied to, for example, vehicle impact detection sensors, coils, planar heating elements, etc.
Claims
1. A resin part having, when observed in cross-section, two or more unevenly thickened portions and a thin-walled portion thinner than the unevenly thickened portions between them, wherein the unevenly thickened portions form a convex portion on one side of the resin part, the resin part is made of a fiber-reinforced composite material containing reinforcing fibers and thermoplastic resin, the unevenly thickened portion has a first resin layer and a second resin layer positioned on the side of the first resin layer, and satisfies the following equations: (1) Vf1 × 0.9 < Vf2 < Vf1 × 1.1 (2) Lw1 > Lw2 (3) 1 mm < Lw2 ≤ W (4) t2 < 7 mm.
2. The resin part according to claim 1, wherein the second resin layer is manufactured using crushed material obtained by crushing a fiber-reinforced composite material containing reinforcing fibers and thermoplastic resin.
3. The resin part according to claim 1, wherein 0.5 < t2 / t1 < 0.9, where t1: thickness of the resin part at the uneven thickness portion.
4. An insert molded body having a resin part and a metal part as described in claim 1, wherein at least a portion of the metal part is arranged on the outer surface of the resin part along the uneven thickness portion or the thin thickness portion, the metal part has a deflection portion whose direction of extension on the outer surface is changed, and the resin part and the metal part are fixed to each other at the deflection portion.
5. The insert molded body according to claim 4, wherein, when the direction perpendicular to the outer surface of the resin part is defined as the thickness direction, the difference in thickness between the unevenly thickened portion and the thinned portion is equal to or greater than the thickness of the metal part.