Foam molded article, vehicle member, and vehicle back door

Abstract

The foam-molded article is obtained by combining a plurality of foam-molded members each having a foamed portion in which a first skin layer, a foamed layer, and a second skin layer are laminated in this order.

Description

Technical Field

[0001] The present disclosure relates to a foamed molded product, a vehicle member, and a vehicle tailgate. Background Art

[0002] Resin structures are lighter than metals and are therefore widely used as vehicle structural parts, vehicle-mounted products, housings of electronic devices, etc. Among resin structures, resin molded products are particularly lightweight and can be expected to improve fuel efficiency if used in vehicle parts such as automobiles.

[0003] For further weight reduction of resin molded products, thinning of the walls of resin molded products is effective. On the other hand, excessive thinning of the walls sometimes leads to reduced rigidity of the resin molded products. In addition, the shapes of ribs, bosses, etc. used to ensure rigidity may damage the surface appearance of the resin molded products.

[0004] As a method for making a resin molded product lightweight while maintaining rigidity, for example, a foaming molding method described in Patent Document 1 is known. In Patent Document 1, after injecting molten resin into a mold cavity of a molding mold formed by a movable mold and a fixed mold, a foaming treatment is performed while the movable mold is slightly opened and moved (core retracted), thereby obtaining a resin molded product. Hereinafter, a resin molded product obtained by performing a foaming treatment is sometimes referred to as a foamed molded product.

[0005] When the molten resin is injected into the mold cavity, the portion in contact with the molding die is cooled and solidified to form a film-like skin layer. If the movable mold is retracted relative to the fixed mold in this state to expand the volume in the mold cavity, the molten resin covered by the skin layer foams to form a foam layer, thereby manufacturing a foamed molded product.

[0006] According to the foam molding method, the foam molded product can be thickened while keeping the weight constant by expanding the volume in the cavity, so that the foam molded product can be lightened and the rigidity can be improved.

[0007] Patent Document 1: Japanese Patent Application Publication No. 2005-238726 Summary of the invention

[0008] Problems to be solved by the invention

[0009] However, when the thickness of the foamed molded product before foaming (the mold cavity before core withdrawal) is set to be the same at any part, the thickness of the foamed molded product changes according to the angle (demolding angle) formed by the opening and closing direction of the molding mold (core withdrawal direction) and the surface of the foamed molded product. Therefore, if the cross-sectional shape of the foamed molded product is complicated, sometimes a part in the foamed molded product that cannot be fully thickened will be generated due to the demolding angle, resulting in insufficient strength of the part. As a market demand, in order to improve designability, the cross-sectional shape of the foamed molded product has increased in complexity.

[0010] As specific examples of foam molded products showing complex cross-sectional shapes, outer panels and inner panels constituting a vehicle back door, spoilers, arch moldings, door trims, etc. are listed. These foam molded products are formed using molds having a variety of demoulding angles, so there is a tendency to easily produce locations with insufficient strength.

[0011] The present disclosure has been made in view of the above-mentioned conventional situation, and an object of the present disclosure is to provide a foamed molded product that can achieve both weight reduction and improvement in rigidity, and a vehicle member and a vehicle tailgate using the foamed molded product.

[0012] Means for solving problems

[0013] The specific means for achieving the above-mentioned objects are as follows.

[0014] <1> A foamed molded product comprising a plurality of foamed molded parts, the foamed molded parts having a foamed portion in which a first skin layer, a foamed layer, and a second skin layer are sequentially laminated.

[0015] <2> A vehicle member comprising the foam-molded article according to <1>.

[0016] <3> A vehicle tailgate including an outer panel and an inner panel provided on the vehicle inner side of the outer panel, wherein at least one of the outer panel and the inner panel includes the foamed molded article according to <1>.

[0017] <4> The vehicle tailgate according to <3>, wherein the outer panel is the foam molded product formed by combining a first foam molded component and a second foam molded component,

[0018] The first molded foam member and the second molded foam member are arranged in the up-down direction.

[0019] <5> The vehicle tailgate according to <3>, wherein the inner panel has an opening for a vehicle window,

[0020] The outer panel is the foam molded product formed by combining a first foam molded component located above the window opening and a second foam molded component located below the window opening.

[0021] The vehicle tailgate further includes a door glass covering the window opening.

[0022] <6> In the vehicle tailgate described in <5>, when observing a cross section of the foamed portion of the first foamed molded component in the thickness direction and a cross section of the foamed portion of the second foamed molded component in the thickness direction, an angle formed by a direction perpendicular to the thickness direction of the foamed portion of the first foamed molded component and a direction perpendicular to the thickness direction of the foamed portion of the second foamed molded component is Displays the relationship between 60° and 90°.

[0023] Effects of the Invention

[0024] According to the present disclosure, it is possible to provide a foamed molded product that can achieve both weight reduction and improvement in rigidity, and a vehicle member and a vehicle tailgate using the foamed molded product. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic cross-sectional view of a molding device 10 used in the foam molding method.

[0026] Figure 2 The figure shows a state where the resin material R is injected and filled into the cavity 14 in the molding device 10 .

[0027] Figure 3 This is a diagram showing a state in which the movable mold 16 is retracted in the opening direction relative to the fixed mold 12 in the molding device 10 .

[0028] Figure 4 It is a rear view showing the vehicle tailgate of the present disclosure.

[0029] Figure 5 yes Figure 4 An exploded perspective view of a tailgate for a vehicle.

[0030] Figure 6 yes Figure 5 End view of line AA in the figure. DETAILED DESCRIPTION

[0031] Hereinafter, the embodiments of the present disclosure are described in detail. However, the present disclosure is not limited to the following embodiments. In the following embodiments, except for the cases specifically indicated, the constituent elements (including element steps, etc.) are not essential. The numerical values ​​and their ranges are also the same and do not limit the present disclosure.

[0032] In the present disclosure, a numerical range expressed using "to" includes the numerical values ​​described before and after "to" as the minimum value and the maximum value, respectively.

[0033] In the numerical ranges described in stages in the present disclosure, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of the numerical range described in another stage.

[0034] In the present disclosure, the terms “layer” or “film” include not only a case where the layer or film is formed on the entire region when the region where the layer or film exists is observed, but also a case where the layer or film is formed on only a part of the region.

[0035] In the present disclosure, the term “stacked” means stacking layers, and two or more layers may be combined or two or more layers may be detachable.

[0036] [Foamed molded product and method for producing the same]

[0037] The foamed molded product disclosed in the present invention is formed by combining a plurality of foamed molded components, and the foamed molded component has a foamed portion in which a first skin layer, a foamed layer, and a second skin layer are sequentially laminated.

[0038] In the present disclosure, one component obtained by primary molding based on the foam molding method is referred to as a foam molded component.

[0039] According to the present disclosure, a foamed molded product that can achieve both weight reduction and improvement in rigidity can be obtained.

[0040] The foamed molded product of the present disclosure is particularly effective in that even a foamed molded product having a complex cross-sectional shape can achieve both weight reduction and improvement in rigidity.

[0041] Hereinafter, a method for producing a foam-molded product by a foam-molding method will be described in outline with reference to the drawings.

[0042] Figure 1 It is a schematic cross-sectional view of a foam molding device used in a foam molding method. It should be noted that the sizes of the components in each figure are conceptual, and the relative relationship between the sizes of the components is not limited to this. In addition, sometimes the same symbols are given to components or parts with the same function in all the drawings, and their descriptions are omitted.

[0043] like Figure 1 As shown, the molding device 10 includes a fixed mold 12 and a movable mold 16. The movable mold 16 can be moved relative to the fixed mold 12. Figure 1 The movable mold 16 moves in the opening and closing direction A indicated by the middle arrow, and forms a cavity 14 as a gap between the movable mold 16 and the fixed mold 12. Hereinafter, the fixed mold 12 and the movable mold 16 may be collectively referred to as a "mold 17".

[0044] The cavity 14 is the gap between the cavity surface 12A and the core surface 16A when the fixed mold 12 and the movable mold 16 are clamped. Figure 1In the embodiment, the thickness of the cavity 14 is the same L0 at any position.

[0045] The cavity 14 corresponds to the shape of the foamed product before foaming. Figure 1 The draft angle θ formed between the opening and closing direction A and the cavity surface 12A or the core surface 16A shown in the figure coincides with the draft angle θ formed between the opening and closing direction A and the surface of the foam-molded product before foaming.

[0046] In the cavity 14 , a draft angle θ formed between the opening and closing direction A and the cavity surface 12A or the core surface 16A changes depending on the shape of the cavity 14 .

[0047] exist Figure 1 In the region X in FIG. 1 , the demolding angle θ formed between the opening and closing direction A and the cavity surface 12A or the core surface 16A is approximately 0°. Figure 1 In the region Y in the middle, the demolding angle θ formed by the opening and closing direction A and the cavity surface 12A or the core surface 16A is approximately 90°. Figure 1 In the region Z in FIG. 1 , a draft angle θ formed between the opening and closing direction A and the cavity surface 12A or the core surface 16A is an angle greater than 0° and less than 90°.

[0048] Furthermore, the molding device 10 includes: a gate 18 that penetrates the fixed mold 12 to the cavity 14; and an injection machine 20 that injects and fills the cavity 14 with a molten resin material R through the gate 18. The injection machine 20 includes a hopper (supply unit) not shown and a barrel not shown. In the injection machine 20, a mixture containing a resin, a foaming agent, an additive, etc. is supplied from the hopper (supply unit) to the barrel, and is stirred by a screw or the like in the barrel to be modulated into a resin material R, and the resin material R is injected and filled into the cavity 14 through the gate 18 at a predetermined pressure. It should be noted that the injection machine 20 is not limited to the above-mentioned structure as long as it can inject and fill the cavity 14 with a molten resin material R through the gate 18.

[0049] For example, a foamed molded product can be manufactured in the following manner: a resin material R containing a foaming agent is injected into the cavity 14 of a mold 17. After the cavity 14 is filled with the resin material, the movable mold 16 is moved from the fixed mold 12 constituting the mold 17 in the opening direction of the movable mold 16 in the opening and closing direction A to expand the volume in the cavity 14.

[0050] like Figure 2 As shown, a resin material R containing a foaming agent is injected and filled into the cavity 14 from an injection machine 20 through a gate 18. When the resin material R is composed of a thermoplastic resin, the resin material R is heated to be fluidized and then supplied into the cavity 14.

[0051] The barrel temperature of the injection machine 20 is preferably less than or equal to 250° C. By setting the barrel temperature of the injection machine 20 to less than or equal to 250° C., it is possible to suppress the escape of foaming gas from the hopper outlet side, and it is easy to obtain the effects of improving and stabilizing the foaming property during molding. The barrel temperature of the injection machine 20 may also be greater than or equal to 150° C.

[0052] The resin material used in the present disclosure is not particularly limited. For example, the resin material used for injection foam molding usually contains a resin and a foaming agent. As the resin for the resin material R, at least one selected from the group consisting of polyethylene resin, polypropylene resin (PP), composite polypropylene resin (PPC), polystyrene resin, polyethylene terephthalate resin, polyvinyl alcohol resin, vinyl chloride resin, ionomer resin, polyamide resin, acrylonitrile-butadiene-styrene copolymer resin (ABS) and polycarbonate resin can be cited. Among them, at least one selected from the group consisting of polypropylene resin (PP), composite polypropylene resin (PPC) and acrylonitrile-butadiene-styrene copolymer resin (ABS) can be cited.

[0053] The resin material may contain a fiber component as required. Examples of the fiber component include inorganic fibers such as carbon fibers, glass fibers, metal fibers, and ceramic fibers, and organic fibers such as aramid fibers and cellulose fibers.

[0054] In addition, examples of the foaming agent include organic foaming agents such as azodicarbonamide, inorganic foaming agents such as sodium bicarbonate (also known as sodium bicarbonate, baking soda), etc. Currently, inorganic sodium bicarbonate is mainly used as a foaming agent in foam molding of automotive interior parts, but organic foaming agents can also be used.

[0055] Examples of the organic foaming agent include azodicarbonamide (ADCA), N,N-dinitrosopentamethylenetetramine (DPT), 4,4-oxybisbenzenesulfonylhydrazide (OBSH), and hydrazonodicarbonamide (HDCA). Azodicarbonamide (ADCA) is preferred.

[0056] Furthermore, the temperature of the mold 17 is usually lower than that of the supplied resin material R. Therefore, by filling the cavity 14 with the resin material R, the curing (formation of the skin layer) of the resin material R starts from the portion in contact with the mold.

[0057] It should be noted that nitrogen may be pre-filled into the cavity 14 before the resin material R is injected into the cavity 14. In this case, the nitrogen may also be heated. By heating the filled nitrogen, the rapid temperature drop in the cavity 14 (mold 17) is suppressed, and there is a tendency for the foaming property of the resin material R to be stabilized. In addition, by heating the filled nitrogen, the external temperature dependence of the foaming power of the resin material R can be suppressed without being affected by the external temperature, and there is a tendency for the foaming property of the resin material R to be stabilized.

[0058] The temperature of the nitrogen gas filled in the cavity 14 is not particularly limited as long as it is a temperature that can suppress a rapid temperature drop in the cavity 14 (mold 17 ), and may be 30° C. to 50° C. from the viewpoint of molding stability.

[0059] Then, if Figure 3 As shown, the movable mold 16 is opened (retracted) in the opening direction relative to the fixed mold 12 by a predetermined amount, so that the uncured resin material R is foamed to form a foam layer 22, thereby obtaining a foamed molded product. Figure 3 As shown, skin layers 24 (first skin layer and second skin layer) are formed in contact with the cavity surface 12A and the core surface 16A so as to surround the foam layer 22 .

[0060] Here, the thickness L of the foamed molded product is expressed by the following formula A using the thickness L0 of the foamed molded product before foaming, the core retreat amount LB, and the demolding angle θ formed by the opening and closing direction A and the surface of the foamed molded product before foaming (i.e., the demolding angle formed by the opening and closing direction A and the cavity surface 12A or the core surface 16A).

[0061] L=L0+LB·sinθ…Formula A

[0062] When the thickness of the foamed molded product before foaming is uniform (i.e., when L0 in Formula A is constant), in the region where the draft angle θ is close to 90°, the thickness L is the thickness obtained by adding the core retreat amount LB to the thickness L0. On the other hand, as the draft angle θ approaches 0°, the thickness of the thickness L corresponding to the draft angle θ decreases.

[0063] For example, Figure 3 The thickness L of the foamed molded article in the region X is L0, in the region Y is L0+LB, and in the region Z is L0+LB·sinθ.

[0064] Hereinafter, taking the case where L0 is 1.50 mm and LB is 1.60 mm as an example, Table 1 shows the value of the thickness L of the foamed molded product when the draft angle θ is changed.

[0065] [Table 1]

[0066]

[0067] The bending rigidity of an object is proportional to the elastic modulus of the object and the cube of the plate thickness. In addition, if the elastic modulus of the foamed product before foaming is compared with the elastic modulus of the foamed product after foaming after core removal, the elastic modulus of the foamed product after foaming is lower than the elastic modulus of the foamed product before foaming.

[0068] Therefore, it is preferred to set the core withdrawal amount and the thickness of the foamed molded product before foaming in a manner to obtain a predetermined bending rigidity by considering the increase in strength caused by the increased plate thickness due to core withdrawal and the decrease in the elastic modulus of the molded product due to foaming.

[0069] However, in a foam molded product, if the draft angle θ is small, a region where no foam layer is formed after core removal may occur (for example, Figure 3 In particular, it is difficult to form a foam layer in a region where the demolding angle θ is less than 30°. In a foamed article, a region where a foam layer is formed after core removal (e.g. Figure 3 When the area of ​​region Y and region Z in the core is relatively small relative to the area of ​​the region where the foaming layer is not generated after the core is withdrawn, the light weight and rigidity improvement effect brought by the foaming molding method may not be enjoyed. It should be noted that in this draft, the area of ​​the region where the foaming layer is generated after the core is withdrawn and the area of ​​the region where the foaming layer is not generated after the core is withdrawn refer to the area of ​​each region when the foaming molded part is observed from the thickness direction.

[0070] Therefore, in the foam molded product disclosed in the present invention, a plurality of foam molded parts having a foamed portion formed by stacking a first skin layer, a foaming layer, and a second skin layer in sequence are combined. By making the foam molded product have such a structure, when each foam molded part is molded by the foam molding method, it is easy to select the optimal demolding angle θ to obtain the foam molded part. In addition, in each foam molded part, it is easy to make a difference between the area of ​​the region where the foam layer is generated after core withdrawal and the area of ​​the region where the foam layer is not generated after core withdrawal. Therefore, the foam molded parts can respectively enjoy the effects of light weight and improved rigidity brought by the foam molding method. As a result, light weight and improved rigidity can also be achieved for the foam molded product.

[0071] The foam molded product disclosed in the present invention is formed by combining a plurality of foam molded components, and may be formed by combining two foam molded components, or may be formed by combining three or more foam molded components.

[0072] The method for producing each molded foam component is the same as the method for producing the above-mentioned molded foam product, and specific examples of the resin material used for producing the molded foam component are also as described above.

[0073] [Vehicle member and vehicle tailgate]

[0074] The foam molded article disclosed in the present invention is useful as a vehicle component used in vehicles such as automobiles and railways. That is, the vehicle component disclosed in the present invention may include the foam molded article disclosed in the present invention. The foam molded article disclosed in the present invention is particularly suitable for use as at least one of the outer plate and the inner plate in a vehicle tailgate having an outer plate and an inner plate arranged on the inner side of the outer plate. If it is desired to obtain vehicle components such as the outer plate and inner plate, spoiler, arched molding, and door exterior trim that constitute the vehicle tailgate by foam molding, due to the diversity of its demoulding angle, sometimes a portion where sufficient thickening cannot be achieved will result in insufficient rigidity of the portion. By applying the foam molded article disclosed in the present invention to vehicle components, there is a tendency to suppress the generation of portions with insufficient rigidity.

[0075] Figure 4 The tailgate 40 is shown in a state where a tailgate opening (not shown) of the vehicle body 30 indicated by a two-dot chain line is closed. The tailgate 40 is attached to the vehicle body 30 and has a function of opening and closing the tailgate opening.

[0076] The tailgate 40 includes an inner panel 42 (see Figure 5 ), outer panel 44 (refer to Figure 5 ) and reinforcing members not shown.

[0077] like Figure 5 As shown, the inner panel 42 is a resin plate material constituting the vehicle inner side portion of the tailgate 40. The inner panel 42 has an opening 43 for a vehicle window.

[0078] like Figure 5 As shown, the outer panel 44 is a member formed by combining an upper outer panel 44A which is a first foamed molded component located above the window opening 43 and a lower outer panel 44B which is a second foamed molded component located below the window opening 43. Figure 5 As shown, the first foam molded component and the second foam molded component are arranged in the vertical direction. The upper outer panel 44A has a rear spoiler structure. The outer panel 44 is mounted on the inner panel 42. As an example, the outer panel 44 is mounted on the inner panel 42 using an adhesive, but the present disclosure is not limited to this.

[0079] Furthermore, a rear window glass 46 as a door glass covering the window opening 43 is attached to the tailgate 40 .

[0080] Figure 6 4 is an end view of the outer plate 44 (upper outer plate 44A and lower outer plate 44B) taken along line AA. Figure 6As shown, when observing the cross section (end face) in the thickness direction of the foamed portion of the first foamed molded component, i.e., the upper outer panel 44A, and the cross section (end face) in the thickness direction of the foamed portion of the second foamed molded component, i.e., the lower outer panel 44B, the angle formed by the direction B perpendicular to the thickness direction of the foamed portion of the upper outer panel 44A and the direction C perpendicular to the thickness direction of the foamed portion of the lower outer panel 44B is It should be noted that the direction B and the direction C may be directions orthogonal to the thickness direction of any foaming part of the upper outer panel 44A and the lower outer panel 44B. Figures 4 to 6 In the case of a rear spoiler structure as shown in FIG. Figure 6 As shown in FIG. 1 , the direction B may be set to be a direction orthogonal to the thickness direction of the top surface portion of the rear spoiler structure of the upper outer panel 44A. Figure 6 As shown, the direction C can be set to be a direction perpendicular to the thickness direction of the portion of the lower outer panel 44B where the license plate (car license plate) is mounted or the flat portion near the portion. It should be noted that when specifying the directions B and C, ribs and bosses are excluded.

[0081] If you want to form an angle with a single foam molding If the outer panel 44 shows a relationship of 60° to 90°, the area without the foaming layer will increase after the core is withdrawn, which may result in a situation where both lightness and rigidity cannot be achieved. According to the present disclosure, since the upper outer panel 44A and the lower outer panel 44B are combined to form the outer panel 44, even if the outer panel 44 is angled as a whole, Even when the relationship is 60° to 90°, the region where the foamed layer is not formed in the upper outer panel 44A and the lower outer panel 44B can be reduced, and both the weight reduction and the improvement of the rigidity of the outer panel 44 can be achieved.

[0082] The disclosed contents of Japanese Patent Application No. 2022-157105 filed on September 29, 2022 are incorporated into this specification by reference in their entirety.

[0083] All documents, patent applications, and technical standards described in this specification are incorporated herein by reference to the same extent as if each individual document, patent application, or technical standard was specifically and individually described as being incorporated by reference.

[0084] Explanation of symbols

[0085] 10: Molding device

[0086] 12: Fixed mold

[0087] 14: Cavity

[0088] 16: Movable mold

[0089] 17: Mould

[0090] 22: Foaming layer

[0091] 24: Epidermis

[0092] 30: Body

[0093] 40: Back door

[0094] 42: Inner plate

[0095] 43: Opening for car window

[0096] 44: Outer panel.

Claims

1. A foamed molded product, which is formed by combining a plurality of foamed molded parts, wherein the foamed molded parts have a foamed portion in which a first skin layer, a foamed layer and a second skin layer are sequentially laminated.

2. A vehicle member comprising the foamed molded product according to claim 1. 3 . A vehicle tailgate comprising an outer panel and an inner panel provided on the vehicle inner side of the outer panel, wherein at least one of the outer panel and the inner panel comprises the foamed molded article according to claim 1 .

4. The vehicle tailgate according to claim 3, wherein the outer panel is the foam molded product formed by combining a first foam molded component and a second foam molded component. The first molded foam member and the second molded foam member are arranged in the up-down direction.

5. The vehicle tailgate according to claim 3, wherein the inner panel has an opening for a vehicle window. The outer panel is the foam molded product formed by combining a first foam molded component located above the window opening and a second foam molded component located below the window opening. The vehicle tailgate further includes a door glass covering the window opening.

6. The vehicle tailgate according to claim 5, wherein when observing a cross section of the foamed portion of the first foamed molded component in the thickness direction and a cross section of the foamed portion of the second foamed molded component in the thickness direction, an angle formed by a direction perpendicular to the thickness direction of the foamed portion of the first foamed molded component and a direction perpendicular to the thickness direction of the foamed portion of the second foamed molded component is Displays the relationship between 60° and 90°.

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