Molded articles, automotive components, and methods for manufacturing molded articles

Abstract

To provide a molded body that has excellent mounting accuracy of a component, an automobile member including the molded body, and a method for manufacturing the molded body.SOLUTION: A molded body has an outer surface and an inner surface, and a foam portion including a foam layer. The foam portion has an opening that penetrates from the outer surface to the inner surface. A peripheral portion pf the opening does not include the foam layer, or a thickness of the foam layer in the peripheral portion is smaller than a thickness of the foam layer on the outside of the peripheral portion.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a molded body, an automotive member, and a method for manufacturing the molded body.

Background Art

[0002] In recent years, for the purpose of weight reduction of automobiles, replacement of metal members with resin members in interior and exterior parts has been progressing. Among them, a molded body containing bubbles (cells) obtained by foaming a resin is lighter than metal, and further improvement in the fuel efficiency of automobiles is expected.

[0003] As a foamed molded body used as an automotive part, for example, one obtained by the method described in Patent Document 1 is known. In this method, a resin is injected into a cavity formed in a pair of molding dies, and the resin is foamed to produce a molded body.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Various parts may be attached to the molded body as described above. For example, a part may be attached by fitting a part of the part into an opening provided in the molded body. However, when an opening is provided in a molded body obtained by foaming a resin, since the foaming of the resin and the formation of the opening are performed simultaneously, the shape of the opening is affected by the behavior of the resin, and there is a risk that the attachment of the part cannot be performed accurately. In view of the above circumstances, an object of the present disclosure is to provide a molded body excellent in the attachment accuracy of parts, an automotive member including the molded body, and a method for manufacturing the molded body.

Means for Solving the Problems

[0006] The following embodiments are included as specific means for solving the above problems. <1> It has an outer surface and an inner surface, and a foamed portion including a foamed layer, The foamed portion has an opening that penetrates from the outer surface to the inner surface. A molded body wherein the periphery of the opening does not include the foam layer, or the thickness of the foam layer at the periphery is less than the thickness of the foam layer outside the periphery. <2> The inner surface of the peripheral portion is parallel to the outer surface of the peripheral portion. <1> The molded body described above. <3> The area of ​​the outer surface of the opening is larger than the area of ​​the inner surface of the opening. <1> or <2> The molded body described above. <4> The foamed portion is in a state where the foamed layer is positioned between the skin layer positioned on the outer surface and the skin layer positioned on the inner surface. <1> ~ <3> A molded article as described in any one of the items. <5> <1> ~ <4> Automotive component comprising a molded body as described in any one of the items. <6> <1> ~ <4> A method for manufacturing a molded article according to any one of the items, A step of supplying a composition containing resin and a foaming agent into the gap between the mold on the outer surface side and the mold on the inner surface side of the molded body, The process includes moving the inner surface mold in a direction away from the outer surface mold, A method for manufacturing a molded body, wherein the inner surface mold has a movable portion in a region including the opening and the peripheral edge of the molded body, and the movable portion protrudes in the opposite direction to the direction of movement when the inner surface mold is moved. [Effects of the Invention]

[0007] This disclosure provides a molded body with excellent mounting accuracy for parts, an automotive component including the molded body, and a method for manufacturing the molded body. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic cross-sectional view showing an example of the shape of a molded body. [Figure 2] This is a schematic cross-sectional view showing an example of the shape of a molded body. [Figure 3] This is a schematic cross-sectional view showing an example of the shape of a molded body. [Figure 4] This is a schematic cross-sectional view showing an example of a method for manufacturing a molded article. [Figure 5] This is a schematic cross-sectional view showing an example of a method for manufacturing a molded article. [Figure 6] This is a schematic cross-sectional view showing an example of a method for manufacturing a molded article. [Modes for carrying out the invention]

[0009] The embodiments for carrying out the present invention will be described in detail below. However, the present invention is not limited to the following embodiments. In the following embodiments, the components (including elemental steps, etc.) are not essential unless otherwise specified. The same applies to numerical values ​​and their ranges, and they do not limit the present invention.

[0010] In this disclosure, the term "process" includes not only processes that are independent of other processes, but also processes that cannot be clearly distinguished from other processes, provided that the purpose of such process is achieved.

[0011] In this disclosure, the numerical range indicated using "~" includes the numbers before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Furthermore, the upper or lower limit of the numerical ranges described in this disclosure may be replaced with the values ​​shown in the examples. In this disclosure, if there are multiple substances corresponding to each component in the composition, unless otherwise specified, the content of each component in the composition refers to the total content of those multiple substances present in the composition. In the present disclosure, the term "layer" includes not only the case where it is formed over the entire region where the layer exists when observing the region, but also the case where it is formed only in a part of the region. When describing embodiments in the present disclosure with reference to the drawings, the configuration of the embodiment is not limited to the configuration shown in the drawings. The size of the members in each figure is conceptual, and the relative relationship of the sizes between the members is not limited thereto.

[0012] <Formed body> The formed body of the present disclosure has an outer surface and an inner surface, and a foamed portion including a foamed layer. The foamed portion has an opening penetrating from the outer surface to the inner surface. The formed body is such that the peripheral portion of the opening does not include the foamed layer, or the thickness of the foamed layer at the peripheral portion is smaller than the thickness of the foamed layer outside the peripheral portion.

[0013] In the present disclosure, the "outer surface" means the surface that becomes the outer side when the formed body is in use (for example, the side observed when the formed body is attached to an automobile), and the "inner surface" means the surface that becomes the inner side when the formed body is in use. In the present disclosure, the "foamed layer" means a portion in a state where cells are included in a resin, the "foamed portion" means a region where the foamed layer exists inside when the formed body is viewed in plan view, and the "thickness of the foamed layer" means the dimension of the foamed layer in the thickness direction of the formed body.

[0014] The formed body of the present disclosure is such that the peripheral portion of the opening does not include the foamed layer, or the thickness of the foamed layer at the peripheral portion of the opening is smaller than the thickness of the foamed layer outside the peripheral portion. That is, the foamed layer is not formed at the peripheral portion, or the formation of the foamed layer is suppressed compared to the outside of the peripheral portion. If the foamed layer is not formed at the peripheral portion of the opening, or the formation of the foamed layer is suppressed, the shape of the opening is less likely to be affected by the behavior during the foaming of the resin. As a result, an opening having a desired shape can be stably formed.

[0015] Figure 1 is a schematic cross-sectional view showing an example of the shape of the molded article of this disclosure before the foam layer is formed. For convenience of explanation, in Figure 1, the state before the foam layer is formed is also referred to as the molded article. The molded body 10 has an outer surface 1, an inner surface 2, and an opening 3 that penetrates from the outer surface 1 to the inner surface 2. Figure 2 is a schematic cross-sectional view showing the shape of the molded body 10 after a foam layer has been formed inside, as shown in Figure 1. After the foam layer is formed, the distance between the outer surface 1 and the inner surface 2 of the molded body 10 is greater than the distance between the outer surface 1 and the inner surface 2 shown in Figure 1. As this expansion occurs, a foam layer is formed inside the molded body 10. On the other hand, the distance between the outer surface 1 and the inner surface 2 at the peripheral edge 4 of the opening 3 is the same as the distance between the outer surface 1 and the inner surface 2 before the foam layer was formed. In other words, at the peripheral edge 4 of the opening 3, a foam layer is not formed due to the expansion of the distance between the outer surface 1 and the inner surface 2, or its formation is suppressed.

[0016] Figure 3 is a schematic cross-sectional view showing the molded body 10 shown in Figure 2 with part 5 attached. In Figure 3, the claws (protruding parts) of part 5 are fitted into the opening 3 of the molded body 10. Because the shape of the peripheral edge 4 of the opening 3 matches the shape of the claws of part 5, the claws are less likely to come loose or shift, and part 5 can be attached to the molded body 10 with high precision.

[0017] From the viewpoint of the accuracy of component mounting, it is preferable that the molded article of the present disclosure has no foam layer at the periphery of the opening, or that the thickness of the foam layer at the periphery is 30% or less of the thickness of the foam layer outside the periphery, more preferably that the periphery of the opening has no foam layer, or that the thickness of the foam layer at the periphery is 15% or less of the thickness of the foam layer outside the periphery, and even more preferably that the periphery of the opening has no foam layer, or that the thickness of the foam layer at the periphery is 5% or less of the thickness of the foam layer outside the periphery. In this disclosure, the thickness of the foam layer outside the periphery of the opening means the thickness of the foam layer in the portion of the foamed area in which the opening is located that is circumstantial to the periphery of the opening. Factors contributing to the formation of a foamed layer around the periphery of the opening include the behavior of the resin during foaming and the unavoidable movement of the mold used in the manufacture of the molded product.

[0018] From the viewpoint of component mounting accuracy, it is preferable that the inner surface at the periphery of the opening in the molded body is parallel to the outer surface at the periphery of the opening. The state of the inner surface at the periphery of the opening can be controlled, for example, by the shape of the mold used in manufacturing the molded body.

[0019] From the viewpoint of component mounting accuracy, it is preferable that the area of ​​the outer surface of the opening is larger than the area of ​​the inner surface. In other words, it is preferable that the shape of the opening narrows from the outer surface to the inner surface (i.e., tapered). The shape of the opening when the molded body is observed from the outer surface is not particularly limited. Specific examples of opening shapes include circular, elliptical, polygonal, and slit shapes.

[0020] It is preferable that the thickness of the periphery of the opening is smaller than the thickness outside the periphery. When the thickness of the periphery of the opening is smaller than the thickness outside the periphery, it is easy to obtain a state in which the periphery of the opening does not contain a foam layer, or in which the thickness of the foam layer at the periphery is smaller than the thickness of the foam layer outside the periphery, using general foam molding techniques. The thickness of the opening, the periphery, and the outer edge of the periphery each refer to the dimensions in the thickness direction of the molded body.

[0021] The thickness of the foamed portion of the molded body (or the average thickness if the thickness is not uniform) is not particularly limited and can be set according to the intended use of the molded body. For example, the thickness of the foamed portion of the molded body may be selected from a range of 1 mm to 6 mm. The thickness of the foamed portion of the molded body may be constant or varied. The average thickness of the foamed area is the arithmetic mean of the thickness measurements taken at 10 locations.

[0022] The molded body may have foamed portions and portions that do not correspond to foamed portions (i.e., portions that do not contain a foamed layer) (for example, the bent portions of the molded body). When a molded body has both foamed areas and areas that are not foamed, the proportion of the foamed area to the entire molded body is not particularly limited and can be set according to the intended use of the molded body. For example, the proportion of the foamed area to the entire molded body may be 50% to 100%, 70% to 100%, or 80% to 100% based on area when the molded body is observed from the outer surface.

[0023] The foamed portion of the molded body may have a foamed layer positioned between the skin layer on the outer surface and the skin layer on the inner surface. In this disclosure, the skin layer means a cell-free layer formed by foaming of the resin.

[0024] The type of resin included in the molded article is not particularly limited. From the viewpoint of ease of molding and balance between toughness and strength, it is preferable that the resin included in the molded article be a thermoplastic resin. The molded article may contain only one type of resin or two or more types.

[0025] Specifically, the resins include at least one selected from the group consisting of polyethylene resins, polypropylene resins, composite polypropylene resins, polystyrene resins, polyethylene terephthalate resins, polyvinyl alcohol resins, vinyl chloride resins, ionomer resins, polyamide resins, acrylonitrile-butadiene-styrene copolymer resins (ABS), and polycarbonate resins. Among these, at least one selected from the group consisting of polypropylene resins, composite polypropylene resins, and acrylonitrile-butadiene-styrene copolymer resins (ABS) is preferred.

[0026] The molded article may contain components other than resin as needed. Examples of components other than resin include inorganic fillers, rubber, additives such as carbon black, and components derived from foaming agents, which will be described later. If the molded article contains components other than resin, the total amount is preferably 15% by mass or less of the total amount of the molded article, more preferably 10% by mass or less, and even more preferably 5% by mass or less.

[0027] If the molded article contains components other than resin, the total amount of resin is preferably 85% by mass or more of the total amount of the molded article, more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0028] The applications of the molded articles of this disclosure are not particularly limited. Because the molded articles of this disclosure are lightweight and have excellent strength, they are suitable for use in applications where both weight reduction and strength are important, such as interior and exterior components of automobiles. Specific examples of interior and exterior components of automobiles include sacco moldings, arch moldings, side moldings, rocker moldings, bumpers, and back door trims.

[0029] <Automotive components> The automotive components of this disclosure include the molded articles described above. There are no particular restrictions on the types of automotive components; they can be selected from automotive interior and exterior components such as sacco moldings, arch moldings, side garnishes, side moldings, rocker moldings, bumpers, back door trims, and side door trims.

[0030] <Method for manufacturing molded articles> The method for manufacturing a molded article described herein is the method for manufacturing a molded article described above, A step of supplying a composition containing resin and a foaming agent into the gap between the mold on the outer surface side and the mold on the inner surface side of the molded body, The process includes moving the inner surface mold in a direction away from the outer surface mold, The mold on the inner surface side has a movable part at a position corresponding to the region including the opening and the peripheral edge of the molded body, and the movable part is made to protrude in the opposite direction to the direction of movement when the mold on the inner surface side is moved.

[0031] In the above method, the volume of the void into which the composition is supplied is increased by moving the inner mold away from the outer mold after the composition has been supplied. At that time, the foaming agent contained in the composition causes the composition to foam and form a foamed layer.

[0032] In the above method, the inner mold has a movable part at a position corresponding to the opening and its peripheral edge of the molded body, and when the inner mold is moved, the movable part is made to protrude in the opposite direction to the direction of movement of the mold. As a result, even if the distance between the inner mold and the outer mold increases, the movable part remains in the same position as before the inner mold was moved. Consequently, a foamed layer is formed in the area where the distance between the inner mold and the outer mold increases (i.e., outside the peripheral edge of the opening), while a foamed layer is not formed or its formation is suppressed in the area where the movable part and the outer mold face each other (i.e., the peripheral edge of the opening).

[0033] In the above method, it is preferable that the distance the movable part on the inner surface side protrudes is the same as the distance the mold on the inner surface side moves away from the mold on the outer surface side. However, depending on the control capability of the movable part, the distance the movable part on the inner surface side protrudes may differ from the distance the mold on the inner surface side moves away from the mold on the outer surface side. In this case, it is preferable that the distance the movable part on the inner surface side protrudes is 85% or more of the distance the mold on the inner surface side moves away from the mold on the outer surface side, from the viewpoint of suppressing the formation of a foam layer at the periphery of the opening, more preferably 90% or more, and even more preferably 95% or more.

[0034] An example of a method for manufacturing the molded article of this disclosure will be described with reference to the drawings. Figure 4 is a schematic cross-sectional view illustrating an example of a method for manufacturing a molded article, showing a state in which a composition containing resin and a foaming agent is supplied to the gap between the mold 11 on the outer surface side of the molded article and the mold 12 on the inner surface side. The mold 11 on the outer surface side has a protrusion at a position corresponding to the opening of the molded body. The inner mold 12 has a movable part 13 at a position corresponding to the area including the opening of the molded body and its peripheral edge.

[0035] Figure 5 shows the state in which the inner mold 12 is moved away from the outer mold 11 (core back) while the composition is supplied to the gap between the outer mold 11 and the inner mold 12 shown in Figure 4. By moving the inner mold 12 away from the outer mold 11, the volume of the void into which the composition is supplied increases, causing the composition to foam and form a foamed layer. The movable part 13 provided on the inner mold 12 protrudes in the opposite direction to the movement of the inner mold 12 and remains in the same position as before the inner mold 12 moved. As a result, no foam layer is formed between the movable part 13 and the outer mold 11, or its formation is suppressed. The method for making the movable part 13 protrude is not particularly limited, and known means such as springs and hydraulics can be used.

[0036] Figure 6 shows the state in which the inner mold 12 and movable part 13 are moved away from the molded body, which is the solidified material of the composition. After this, the molded body is removed from the outer mold 11, and the manufacturing process of the molded body is completed.

[0037] In the molded product manufactured by the method of this disclosure, it is preferable that the foamed portion is in a state in which a foamed layer is positioned between the skin layers arranged on the outer surface and the inner surface. The state in which skin layers are arranged on both the outer and inner surfaces is achieved by adjusting the temperature of the parts of the mold that come into contact with the composition. Specifically, by adjusting the temperature of the mold so that the solidification of the part of the composition supplied to the gap between the molds that comes into contact with the mold surface proceeds faster than other parts, the part of the composition near the mold does not foam during core backing and forms a skin layer, while the other parts foam and form a foamed layer.

[0038] In the method disclosed herein, the type of resin included in the composition is not particularly limited and may be selected from among the resins that may be included in the molded articles described above.

[0039] The type of blowing agent included in the composition is not particularly limited; both organic and inorganic blowing agents can be used. Examples of organic blowing agents include azodicarbonamide (ADCA), N,N-dinitrosopentamethylenetetramine (DPT), 4,4-oxybisbenzenesulfonyl hydrazide (OBSH), and hydrazodicarbonamide (HDCA). Examples of inorganic blowing agents include sodium bicarbonate.

[0040] Among organic blowing agents, azodicarbonamide (ADCA) is preferred when the molded body is an exterior component. The use of azodicarbonamide (ADCA) improves resistance to hot water and tends to suppress the occurrence of blisters in hot water tests. Blisters refer to a condition in which gas generated by the reaction of unreacted foaming agent remaining in the skin layer with water pushes up the skin layer.

[0041] In the above method, the temperature of the composition when supplied to the molding apparatus is not particularly limited. If the composition contains a thermoplastic resin, it is preferable that the temperature is above its softening point. [Explanation of Symbols]

[0042] 1...Outer surface, 2...Inner surface, 3...Opening, 4...Periphery of the opening, 5...Part, 10...Molded body, 11...Mold on the outer surface side, 12...Mold on the inner surface side, 13...Movable part

Claims

1. It has an outer surface and an inner surface, and a foamed portion including a foamed layer, The foamed portion has an opening that penetrates from the outer surface to the inner surface. The area of ​​the outer surface of the opening is larger than the area of ​​the inner surface of the opening. The peripheral edge of the opening does not include the foam layer, or the thickness of the foam layer at the peripheral edge is less than the thickness of the foam layer outside the peripheral edge. A molded body in which the inner surface of the peripheral portion is parallel to the outer surface of the peripheral portion.

2. The molded article according to claim 1, wherein the foamed portion is in a state in which the foamed layer is disposed between the skin layer disposed on the outer surface side and the skin layer disposed on the inner surface side.

3. An automotive component comprising a molded body according to claim 1 or claim 2.

4. A method for manufacturing a molded article according to any one of claims 1 to 3, A step of supplying a composition containing resin and a foaming agent into the gap between the mold on the outer surface side and the mold on the inner surface side of the molded body, The process includes moving the inner surface mold in a direction away from the outer surface mold, The mold on the outer surface side has a protrusion at a position corresponding to the opening of the molded body, A method for manufacturing a molded body, wherein the inner surface mold has a movable portion in a region including the opening and the peripheral edge of the molded body, and the movable portion protrudes in the opposite direction to the direction of movement when the inner surface mold is moved.

Images