Method for manufacturing press-formed articles, mold apparatus, and manufacturing apparatus

Abstract

In the manufacture of press-molded articles using a fluid molten resin composition as the molding material, the objective is to prevent the resulting molded articles from being in an incomplete state. [Solution] The method for manufacturing a press-molded body includes a molding step of closing a pair of molds (30) and press-molding a molten resin composition (P), the molding step including a flow step of pressing the molten resin composition P in the recess (32a) of the core mold (32) with the convex portion (31a) of the cavity mold (31) to cause the molten resin composition (P) to flow from the first space portion (S1) to the second space portion (S2).

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a press-formed article, a mold apparatus, and a manufacturing apparatus. [Background technology]

[0002] Techniques for manufacturing molded articles containing thermoplastic resin by press molding are disclosed, for example, in Patent Documents 1 and 2.

[0003] Patent Document 1 discloses a method for producing a molded article having an opening by cold-pressing a molding material containing discontinuous carbon fibers and a thermoplastic resin by placing it in a pair of molds. The molding material used in the press molding described in Patent Document 1 is in the form of a sheet having a predetermined tensile elongation at break. Patent Document 2 also discloses a method for producing a molded article that includes a step of press-molding a resin sheet or resin film containing a thermoplastic resin and a fibrous inorganic filler using a pair of molds.

[0004] In addition to the technologies disclosed in Patent Documents 1 and 2, there is also a known technology that uses a fluid molten resin composition obtained by heating a thermoplastic resin as a molding material. In this technology, the molten resin composition is injected between a pair of molds, the pair of molds are closed and press-molded, and then cooled to obtain a molded body. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] International Publication No. 2015 / 194533 [Patent Document 2] International Publication No. 2016 / 167232 [Overview of the project] [Problems that the invention aims to solve]

[0006] It has been found that when a rotationally symmetrical bottomed cylindrical molded body, such as a cup, is press-molded using a fluid molten resin composition as a molding material, the resulting molded body may be in an imperfect state, such as having holes in the side walls or defects at the ends. Therefore, there is room for improvement in conventional press molding techniques using fluid molten resin compositions as molding materials in terms of preventing the resulting molded body from being in an imperfect state.

[0007] One aspect of the present invention aims to realize a method for manufacturing a press-formed article, a mold apparatus, and its use that can prevent the resulting molded article from being in an incomplete state. [Means for solving the problem]

[0008] To solve the above problems, a method for manufacturing a press-molded article according to one aspect of the present invention is a method for manufacturing a press-molded article by supplying a fluid molten resin composition containing a thermoplastic resin to a pair of molds consisting of a core mold and a cavity mold, wherein the pair of molds comprises a first space portion for forming the bottom portion of the press-molded article and a second space portion for forming the side wall portion of the press-molded article, wherein in the first space portion, the core mold has a recess formed on the surface for forming the inner bottom surface of the press-molded article, and the cavity mold has a protrusion formed on the surface for forming the outer bottom surface of the press-molded article that is sized to fit into the recess, and the method includes a resin supply step of filling the recess of the core mold with the molten resin composition, and a molding step of closing the pair of molds and press-molding the molten resin composition, wherein the molding step includes a flow step of flowing the molten resin composition from the first space portion to the second space portion by pressing the molten resin composition in the recess with the protrusion.

[0009] A mold apparatus according to one aspect of the present invention comprises a pair of molds consisting of a core mold and a cavity mold, and is a mold apparatus for manufacturing a rotationally symmetrical bottomed cylindrical press-molded body by supplying a fluid molten resin composition containing a thermoplastic resin to the pair of molds, wherein the pair of molds comprises a first spatial portion for forming the bottom of the press-molded body and a second spatial portion for forming the side wall portion of the press-molded body, wherein in the first spatial portion, the core mold has a recess formed on the surface that forms the inner bottom surface of the press-molded body, which is a portion for containing the molten resin composition, and the cavity mold has a protrusion formed on the surface that forms the outer bottom surface of the press-molded body, which is sized to fit into the recess, and the recess and the protrusion are configured such that the molten resin composition in the recess flows from the first spatial portion to the second spatial portion by pressing the molten resin composition in the recess with the protrusion. [Effects of the Invention]

[0010] According to one aspect of the present invention, it is possible to prevent the resulting molded article from being in an incomplete state. [Brief explanation of the drawing]

[0011] [Figure 1] This figure schematically shows the general configuration of a press-formed article manufacturing apparatus according to an embodiment of the present invention. [Figure 2] 201 is a cross-sectional view showing the schematic configuration of a pair of molds used in a method for manufacturing a press-formed article according to an embodiment of the present invention, and 202 is a cross-sectional view showing the schematic configuration of a press-formed article press-formed by the pair of molds shown in 201. [Figure 3] This is a schematic cross-sectional view showing the behavior of the molten resin composition in the flow step of a method for manufacturing a press-molded article according to an embodiment of the present invention. [Figure 4] This is a schematic diagram showing the relationship between the projected area of ​​the molten resin composition supplied to the first space and the projected area of ​​the first space, as viewed from the cavity mold side, in a pair of molds before the molding process. [Modes for carrying out the invention]

[0012] An embodiment of the present invention will be described in detail below. Unless otherwise specified in this specification, "A~B" representing a numerical range means "A or more and B or less". Also, all the documents described in this specification are incorporated herein by reference as references.

[0013] 〔Summary of the Invention〕 When press molding using a thermoplastic resin, instead of Method A in which a sheet-like material made of a thermoplastic resin is press molded by a pair of molds consisting of a core mold and a cavity mold, Method B is adopted in which a molten resin obtained by heating a thermoplastic resin is press molded while being in a molten state that can flow into a pair of molds consisting of a core mold and a cavity mold. Note that Method A corresponds to the methods disclosed in Patent Documents 1 and 2. Also, Method B is particularly effective when using a biodegradable resin such as a poly(3-hydroxyalkanoate) - based resin as the thermoplastic resin.

[0014] In the production of a press molded article by the above Method B, since the resin composition in the molten state (hereinafter referred to as the molten resin composition) can flow in the mold, the degree of freedom in designing the wall thickness of the molded article is higher compared to Method A using a sheet-like material.

[0015] Particularly, for example, when press molding a rotationally symmetric bottomed cylindrical molded article such as a cup, the following steps (1) and (2) can be adopted to fill the pair of molds with the molten resin composition. (1) Supply the molten resin composition to the space portion (the first space portion) for forming the bottom of the press molded article in the pair of molds. (2) By closing and pressing the pair of molds, the molten resin composition is caused to flow from the space portion for forming the bottom of the press molded article to the space portion for forming the side wall portion of the press molded article (the second space portion).

[0016] According to the verification by the present inventor, when the molten resin composition is filled into a pair of molds and press-molded in the above steps (1) and (2), the obtained press-molded product may be in an incomplete state such as holes opening in the side wall portion or defects occurring at the end portion. In particular, when manufacturing a thin-walled press-molded product with a wall thickness of, for example, 0.3 mm, it is easy to obtain such an incomplete press-molded product.

[0017] And the present inventor considered that the above incomplete state of the press-molded product is due to the poor flow balance of the molten resin composition in the circumferential direction of the outer periphery of the bottomed cylinder of the press-molded product in the space portion for forming the side wall portion of the press-molded product when performing the above (2). Various causes can be considered for deteriorating such a flow balance, such as the inclination of the core mold, the deviation of the molten resin composition in the pair of molds, the deflection of the core mold, the axial misalignment between the pair of molds, and the like. As a result of the intensive study by the present inventor, it was found that the main cause of deteriorating the flow balance of the molten resin composition in the space portion for forming the side wall portion of the press-molded product among these causes is the axial misalignment between the pair of molds. That is, when axial misalignment occurs between the pair of molds when performing the above (2), in the space portion for forming the side wall portion of the press-molded product, in the circumferential direction of the outer periphery of the bottomed cylinder of the press-molded product, there will be a flow path with a narrow flow path width and a flow path with a wide flow path width. In the flow path with a narrow flow path width, the flow resistance of the molten resin composition is large, and it becomes difficult for the molten resin composition to flow to the end portion of the pair of molds (the space portion corresponding to the opening end portion of the press-molded product). On the other hand, in the flow path with a wide flow path width, the flow resistance of the molten resin composition is small, and it becomes easy for the molten resin composition to flow to the end portion of the pair of molds. Thus, when axial misalignment occurs between the pair of molds, in the space portion for forming the side wall portion of the press-molded product, a flow path with a narrow flow path width and a flow path with a wide flow path width occur, and because the ease of flow of the molten resin composition to the end portion of the pair of molds is different between these flow paths, it is considered that the obtained press-molded product is in an incomplete state.

[0018] To ensure a uniform flow balance of the molten resin composition in the space where the side wall of a press-molded body is formed, it is conceivable to arrange a pair of molds coaxially. However, when manufacturing, for example, a thin-walled press-molded body, it is necessary to arrange a pair of molds coaxially with extreme precision, making it difficult to prevent the resulting molded body from being incomplete. Therefore, the inventors have diligently investigated methods to improve the flow balance of the molten resin composition in the space where the side wall of a press-molded body is formed, even if there is axial misalignment between the pair of molds.

[0019] As a result, focusing on the structure of the space portion that forms the bottom of the press-molded body in a pair of molds, we found that by providing a recess on the surface corresponding to the inner bottom surface of the press-molded body in the core mold and a protrusion of a size that fits into the recess on the surface corresponding to the outer bottom surface of the press-molded body in the cavity mold, when (2) above is performed, the flow balance of the molten resin composition in the space portion that forms the side wall portion of the press-molded body can be improved, leading to one embodiment of the present invention.

[0020] In other words, a method for manufacturing a press-molded article according to one embodiment of the present invention (hereinafter sometimes referred to as the "this manufacturing method") is a method for manufacturing a press-molded article by supplying a fluid molten resin composition containing a thermoplastic resin to a pair of molds consisting of a core mold and a cavity mold, thereby manufacturing a rotationally symmetrical bottomed cylindrical press-molded article. The pair of molds comprises a first space portion for forming the bottom portion of the press-molded article and a second space portion for forming the side wall portion of the press-molded article. In the first space portion, the core mold has a recess formed on the surface that forms the inner bottom surface of the press-molded article, and the cavity mold has a protrusion formed on the surface that forms the outer bottom surface of the press-molded article that is sized to fit into the recess. The present manufacturing method includes a resin supply step of filling the recess of the core mold with the molten resin composition, and a molding step of closing the pair of molds and press-molding the molten resin composition, wherein the molding step includes a flow step of pressing the molten resin composition in the recess with the protrusions to cause the molten resin composition to flow from the first space portion to the second space portion.

[0021] Furthermore, a mold apparatus according to one embodiment of the present invention (hereinafter sometimes referred to as "this mold apparatus") is a mold apparatus for manufacturing a rotationally symmetrical bottomed cylindrical press-molded body by supplying a fluid molten resin composition containing a thermoplastic resin to a pair of molds, comprising a core mold and a cavity mold. The pair of molds comprises a first space portion for forming the bottom of the press-molded body and a second space portion for forming the side walls of the press-molded body. In the first space portion, the core mold has a recess formed on the surface that forms the inner bottom surface of the press-molded body, which is a portion for containing the molten resin composition, and the cavity mold has a protrusion formed on the surface that forms the outer bottom surface of the press-molded body, which is sized to fit into the recess. In this mold apparatus, the recess and the protrusion are configured such that the molten resin composition in the recess flows from the first space portion to the second space portion by the protrusion pressing the molten resin composition in the recess.

[0022] Furthermore, this manufacturing method and mold apparatus, when using biodegradable resins such as poly(3-hydroxyalkanoate) resins as thermoplastic resins, can reduce marine pollution from waste, thereby contributing to the achievement of Sustainable Development Goals (SDGs) such as Goal 12, "Ensure sustainable consumption and production patterns," and Goal 14, "Conserve and sustainably use the oceans, seas and marine resources for sustainable development." The manufacturing method and mold apparatus will be described in detail below.

[0023] [Method for manufacturing press-molded products] This manufacturing method comprises a heating step, a resin supply step, and a molding step. In this manufacturing method, a press-molded article of thermoplastic resin is produced through the heating step, the resin supply step, and the molding step.

[0024] In the heating step described above, the resin composition containing the thermoplastic resin is heated to form a molten resin composition. Any conventionally known method can be used for heating the resin composition, as long as it is a method that can form a molten resin composition containing the thermoplastic resin. Preferably, the heating step includes a melt-kneading step in which the resin composition containing the thermoplastic resin is melt-kneaded.

[0025] The form of the melt-kneading process is not particularly limited, as long as a melt-kneaded resin composition can be obtained. Specific examples of the melt-kneading process include, for example, the following methods (a1) and (a2): (a1) A resin composition containing a thermoplastic resin is prepared by mixing or blending using a mixing device or the like. The resin composition is then supplied to a melt-kneading device and melt-kneaded; (a2) A method of supplying raw materials for a resin composition containing a thermoplastic resin to a melt-kneading apparatus, preparing (completing) the resin composition in the melt-kneading apparatus, and melt-kneading the resin composition.

[0026] In method (a1) above, the order in which the raw materials for the resin composition containing the thermoplastic resin are mixed or blended (dry blended) is not particularly limited. In method (a2) above, the order in which the raw materials for the resin composition containing the thermoplastic resin are supplied to the melt kneading apparatus is not particularly limited.

[0027] In the method described in (a1) above, the mixing device is not particularly limited and includes ribbon blenders, flash blenders, tumbler mixers, super mixers, and the like.

[0028] In the methods described in (a1) and (a2) above, the melting and kneading apparatus is not particularly limited and includes extruders, kneaders, Banbar mixers, and rolls. Extruders are preferred as the melting and kneading apparatus due to their superior productivity and convenience, and twin-screw extruders are even more preferred.

[0029] In the melt-mixing process, for example, when using a poly(3-hydroxyalkanoate) resin as the thermoplastic resin, the temperature at which the resin composition is melt-mixed cannot be specified in general terms, as it depends on the physical properties of the poly(3-hydroxyalkanoate) (melting point, weight-average molecular weight, etc.) and the type of additives used. Regarding the temperature at which the resin composition is melt-mixed, for example, the temperature of the melt-mixed resin composition discharged from the discharge unit (hereinafter sometimes referred to as the composition temperature) is preferably 140°C to 190°C, more preferably 150°C to 180°C, and even more preferably 160°C to 170°C. If the composition temperature is 150°C or lower, unmelted thermoplastic resin may be generated. On the other hand, if the composition temperature is 180°C or higher, the thermoplastic resin may undergo thermal decomposition.

[0030] Furthermore, in the resin supply process described above, the molten resin composition is supplied between the pair of molds by being discharged from the discharge unit. In the resin supply process described above, the molten resin composition is discharged from the discharge unit to the pair of molds while still in a molten state. This supplies the molten resin composition in a molten state between the pair of molds.

[0031] The method for supplying the molten resin composition between the molds is not particularly limited, as long as the molten resin composition discharged from the discharge unit can be supplied between the pair of molds. From the viewpoint of reliably supplying the molten resin composition between the pair of molds, it is preferable to first discharge the molten resin composition from the discharge unit to the core mold, supply a predetermined amount of the molten resin composition to the lower mold, and then place the upper mold on the core mold to supply the molten resin composition between the pair of molds.

[0032] Furthermore, in the resin supply process described above, the configuration of the discharge unit is not particularly limited as long as it is capable of discharging the molten resin composition, and conventionally known configurations can be adopted. From the viewpoint of improving the productivity of press-molded products, it is preferable that the discharge unit is capable of quantitatively discharging the molten resin composition. Examples of such discharge unit configurations include configurations equipped with a gear pump and configurations equipped with an automatic opening and closing nozzle. Specific examples of discharge units include plunger-type dischargers, pre-plunger-type dischargers, and screw-type dischargers.

[0033] Furthermore, in the molding process described above, the pair of molds are closed and the flowable molten resin composition is press-molded and cooled. In the resin supply process described above, the molten resin composition is supplied between the pair of molds while still in a molten state, so even if the pair of molds is closed in the molding process described above, the molten resin composition can flow through the space between the pair of molds.

[0034] In the resin supply step described above, the molten resin composition is supplied in a molten state between the pair of molds. Then, in the molding step described above, the pair of molds are subjected to hot pressing using a hot press molding machine. After the hot pressing is complete, the pair of molds are cooled to perform press molding. After press molding, the pair of molds are opened to obtain a press-molded body.

[0035] The hot press molding machine used in the above resin supply process is not particularly limited, as long as it is configured to hot press the pair of molds to which the molten resin composition is supplied. Conventional known devices can be used as the hot press molding machine.

[0036] The method for cooling a pair of molds after hot pressing is not particularly limited. For example, one method involves clamping the pair of molds after hot pressing with a pair of cooling plates and then performing a cooling press.

[0037] In this method, the press pressure during cooling press is not particularly limited, but is preferably 10KN to 100KN, and more preferably 30KN to 50KN. Setting the press pressure within the above numerical range has the advantage of producing a press-molded body with uniform thickness.

[0038] Furthermore, while there are no particular limitations on the pressing time during cooling press, it is preferably 60 to 600 seconds, and more preferably 120 to 300 seconds. Setting the above pressing time within the above numerical range has the advantage that the thermoplastic resin solidifies sufficiently, making it easier to remove the press-molded product.

[0039] Furthermore, while the temperature of the cooling plate used in the cooling press is not particularly limited, it is preferably between 10°C and 60°C, and more preferably between 20°C and 50°C. Setting the temperature of the cooling plate within the above numerical range has the advantage that the thermoplastic resin solidifies sufficiently, making it easier to remove the press-molded product.

[0040] Herein, the manufacturing method is characterized by the structure of the pair of molds that supply the molten resin composition. Figure 201 is a cross-sectional view showing the schematic configuration of the pair of molds 30 used in this manufacturing method. Figure 202 is a cross-sectional view showing the schematic configuration of the press-molded body A that is press-molded by the pair of molds 30.

[0041] As shown in Figure 2, 202, the press-molded body A produced by this manufacturing method is a rotationally symmetrical bottomed cylindrical shape. The press-molded body A is cylindrical with side walls A4, with a bottom A1 formed at one end and an opening A2 at the other end. A recess A3 is formed in the central part of the bottom A1. The press-molded body A is not particularly limited as long as it is a rotationally symmetrical bottomed cylindrical article, for example, a beverage cup.

[0042] Furthermore, this manufacturing method can be applied to the production of thin, bottomed cylindrical press-molded bodies A with a small wall thickness. The wall thickness of the press-molded body A is preferably 0.1 mm to 0.5 mm, and more preferably 0.2 mm to 0.3 mm.

[0043] Furthermore, the press-formed body A to which this manufacturing method can be applied is not particularly limited, as long as it is a rotationally symmetric, bottomed cylindrical shape. Examples of the shape of the press-formed body A include a bottomed regular polygonal prism cylindrical shape, a bottomed cylindrical shape, and so on. Examples of bottomed regular polygonal prism cylindrical shapes include a bottomed regular triangular prism cylindrical shape, a bottomed regular hexagonal prism cylindrical shape, and so on.

[0044] Furthermore, the direction in which the side wall portion A4 of the press-formed body A to which this manufacturing method can be applied is not particularly limited. The side wall portion A4 may extend parallel to the axis of symmetry of the press-formed body A, or it may extend in a tapered shape such that the spacing increases towards the opening A2, or it may extend in a tapered shape such that the spacing decreases towards the opening A2.

[0045] The mold 30 has a molding space formed by a molding surface that is formed to match the rotationally symmetric shape of the press-formed body A. The molding surface is formed rotationally symmetrically with respect to the axis of symmetry X. In the drawings of this application (Figures 1 to 4), the extension direction of the axis of symmetry X is defined as the HD direction (height direction), and the direction perpendicular to the HD direction is defined as the WD direction (width direction). The WD direction can be said to be the radial direction of the rotationally symmetric shape formed by the molding surface. Furthermore, one side (upper side) in the HD direction is defined as the HDa side, and the other side (lower side) is defined as the HDb side.

[0046] As shown in Figure 2, 201, the mold 30 consists of a cavity mold 31 and a core mold 32. The molding space is formed by the cavity mold 31 and the core mold 32. The mold 30 comprises a first spatial portion S1 and a second spatial portion S2 as the molding space for the press-formed body A. In the molding space of the mold 30, the first spatial portion S1 is the molding space for forming the bottom portion A1 of the press-formed body A, and the second spatial portion S2 is the molding space for forming the side wall portion A4 of the press-formed body A.

[0047] Furthermore, in the first spatial portion S1, the cavity mold 31 has a surface 31b that forms the outer bottom surface A12 of the press-molded body A. The core mold 32 has a surface 32b that forms the inner bottom surface A11 of the press-molded body A. In the first spatial portion S1, surfaces 31b and 32b face each other. In the first spatial portion S1, a convex portion 31a is formed on the surface 31b of the cavity mold 31, and a concave portion 32a is formed on the surface 32b of the core mold 32. The convex portion 31a is sized to fit within the concave portion 32a. In this manufacturing method, the convex portion 31a of the cavity mold 31 and the concave portion 32a of the core mold 32 form the recess A3 of the press-molded body A. Furthermore, the convex portion 31a and the concave portion 32a are rotationally symmetric with respect to the axis of symmetry X.

[0048] In this manufacturing method, the resin supply step involves filling the recess 32a of the core mold 32 with a molten resin composition. In this resin supply step, the amount of molten resin composition supplied to the recess 32a should be such that the molten resin composition in the recess 32a can flow into the second spatial portion S2 by closing the pair of molds 30, and can be appropriately set according to the dimensions of the protrusion 31a and the recess 32a, the properties of the molten resin composition, the size of the flow path of the molten resin composition in the second spatial portion S2, etc. Depending on the dimensions of the protrusion 31a and the recess 32a, etc., the amount of molten resin composition supplied to the recess 32a may not be enough to completely fill the recess 32a. From the viewpoint of more reliably ensuring that the molten resin composition in the recess 32a flows into the second spatial portion S2, it is preferable that the amount of molten resin composition supplied to the recess 32a is at least enough to fill the recess 32a.

[0049] Then, in the molding process described above, as stated above, the pair of molds 30 are closed and the flowable molten resin composition is press-molded. Here, in this manufacturing method, the molding process includes a flow process. In this flow process, the molten resin composition in the recess 32a is pressed by the convex portion 31a, causing the molten resin composition to flow from the first spatial portion S1 to the second spatial portion S2.

[0050] In this manufacturing method, even if axial misalignment occurs between the pair of molds 30 due to the flow process described above, the flow balance of the molten resin composition in the second spatial portion S2 corresponding to the side wall portion A4 of the press-molded body A can be improved. Figure 3 is a schematic cross-sectional view showing the behavior of the molten resin composition P during the flow process.

[0051] As shown in Figure 3, we will now describe the case where the axis of symmetry X1 of the cavity mold 31 and the axis of symmetry X2 of the core mold 32 are misaligned immediately after the molten resin composition in the recess 32a is pressed by the convex portion 31a (immediately after pressing).

[0052] As shown in Figure 3, when a misalignment occurs between the symmetry axis X1 of the cavity mold 31 and the symmetry axis X2 of the core mold 32, the width of the flow channels through which the molten resin composition flows becomes uneven in the second spatial portion S2. As shown in Figure 3, in the second spatial portion S2, a flow channel R1 with a flow channel width D1 and a flow channel R2 with a flow channel width D2 are formed. The flow channel width D2 is smaller than the flow channel width D1. As a result, the flow resistance of the molten resin composition P is high in flow channel R2, making it difficult for the molten resin composition P to flow to the end portion of the mold 30 (the spatial portion corresponding to the opening A2 of the press-molded body A). On the other hand, in flow channel R1, the flow resistance of the molten resin composition P is low, making it easier for the molten resin composition P to flow to the end portion of the mold 30. Thus, when axial misalignment occurs between the cavity mold 31 and the core mold 32, a wide flow path R1 and a narrow flow path R2 are created in the second spatial portion S2. Because the ease of flow of the molten resin composition P to the end portions of the pair of molds 30 differs between flow paths R1 and R2, the flow balance of the molten resin composition P in the second spatial portion S2 deteriorates.

[0053] Here, the protrusion 31a of the cavity mold 31 is sized to fit into the recess 32a of the core mold 32, so a gap is created between the side surface of the protrusion 31a and the side wall surface of the recess 32a in the WD direction. For this reason, in the flow process, the first space portion S1 is formed by the protrusion 31a and the recess 32a, creating a flow path r1 through which the molten resin composition P flows into flow path R1, and a flow path r2 through which the molten resin composition P flows into flow path R2. If axial misalignment occurs between the cavity mold 31 and the core mold 32, the flow path width d1 of flow path r1 and the flow path width d2 of flow path r2 become non-uniform. As shown in Figure 3, in the first space portion S1, the flow path width d2 of flow path r2 is larger than the flow path width d1 of flow path r1. As a result, the flow resistance of the molten resin composition P is small in flow path r2, and the molten resin composition P flows more easily to flow path R2 in the second space portion S2. On the other hand, in flow path r1, the flow resistance of the molten resin composition P is high, making it difficult for the molten resin composition P to flow to flow path R1 in the second spatial portion S2. Thus, in the first spatial portion S1, the molten resin composition P does not flow easily through flow path r1, which has high flow resistance, to flow through flow path R1, which has low flow resistance, while the molten resin composition P flows easily through flow path r1, which has low flow resistance, to flow through flow path R2, which has high flow resistance. As a result, the non-uniformity of the flow balance of the molten resin composition P from flow path R1 to the end portions of the pair of molds 30 between flow path R1 and flow path R2 is mitigated. Therefore, even if there is axial misalignment between the pair of molds 30, the flow balance of the molten resin composition in the second spatial portion S2 can be improved. As a result, this manufacturing method makes it possible to prevent the obtained press-molded body A from being in an imperfect state, such as having holes in the side walls or defects at the ends.

[0054] Applying this manufacturing method to a press molding technique for a rotationally symmetrical, bottomed cylindrical press-molded body A has the effect of preventing imperfections such as holes in the side wall A4 or defects at the ends. From the viewpoint of enhancing this effect, the ratio of the length C of the side wall A4 of the press-molded body A to the diameter B of the bottom A1 of the press-molded body A is preferably 1.0 to 5.0, and more preferably 1.0 to 3.0. Applying this manufacturing method to the production of a press-molded body A in which the ratio of the length C of the side wall A4 to the diameter B of the bottom A1 is within the above numerical range will result in a significant effect.

[0055] Here, the diameter B of the base A1 refers to the maximum length of the straight line connecting any two points on the sides of the figure that constitutes the outer shape of the base A1. For example, if the press-formed body A is cylindrical, the diameter B of the base A1 refers to the diameter of the circle that constitutes the outer shape of the base A1. Also, if the press-formed body A is a rectangular prism, the diameter B of the base A1 refers to the length of the diagonal of the square that constitutes the outer shape of the base A1.

[0056] Furthermore, from the viewpoint of making the above effects more pronounced, the depth of the recess 32a of the core mold 32 is preferably 3.0 mm to 9.0 mm, and more preferably 6.0 mm to 9.0 mm. Also, the size of the protrusion 31a is not particularly limited as long as it fits within the recess 32a. From the viewpoint of making the above effects more pronounced, the height of the protrusion 31a is preferably 3.0 mm to 9.0 mm, and more preferably 6.0 mm to 9.0 mm. Also, it is preferable that the height of the protrusion 31a is the same as the depth of the recess 32a.

[0057] Furthermore, when viewed from the HDa side, it is preferable that the shape of the protrusion 31a is the same as the shape of the recess 32a (the shape of the region surrounded by the inner wall). For example, when viewed from the HDa side, if the shape of the protrusion 31a is circular, it is preferable that the shape of the recess 32a is also circular. Also, in the WD direction, the diameter of the protrusion 31a should be smaller than the diameter of the recess 32a (the maximum distance between the opposing inner walls). For example, the diameter of the protrusion 31a can be set based on the calculation result of the following formula 1. The diameter of the protrusion 31a is preferably within the range of ±0.3 mm from the calculation result of the following formula 1, and more preferably within the range of ±0.1 mm from the calculation result of the following formula 1. Diameter of recess 32a - (Average value of flow path R1 in the second spatial portion S2 × 2) Equation 1 Furthermore, the convex portion 31a and the concave portion 32a have a projected area S of the first spatial portion S1, which will be described later. A (See Figure 4) It is preferable that the formation is within the range of 30% to 95%, and more preferably within the range of 50% to 80%.

[0058] In the flow process shown in Figure 3, the cavity mold 31 was placed on the HDa side and the core mold 32 on the HDb side, and the pair of molds 30 were closed. However, the flow process only needs to be able to flow the molten resin composition P in the recess 32a of the core mold 32 into the second spatial portion S2, and the arrangement of the cavity mold 31 and the core mold 32 is not particularly limited. In the flow process of this manufacturing method, the cavity mold 31 may be placed on the HDb side and the core mold 32 on the HDa side, and the pair of molds 30 may be closed. From the viewpoint of the ease with which the molten resin composition P flows into the second spatial portion S2, it is preferable to place the cavity mold 31 on the HDa side and the core mold 32 on the HDb side, as shown in Figure 3, and close the pair of molds 30.

[0059] Figure 4 shows the projected area S of the molten resin composition supplied to the first spatial portion S1, as viewed from the cavity mold 31 side (HDa side) in a pair of molds 30 before the molding process. p and the projected area S of the first spatial portion S1 A This is a schematic diagram showing the relationship. As shown in Figure 4, when viewed from the cavity mold 31 side (HDa side), the projected area S of the molten resin composition pis smaller than the projected area S of the first space portion S1 A Also, when viewed from the cavity mold 31 side (HDa side), the molten resin composition supplied to the first space portion S1 is circular in shape.

[0060] From the viewpoint of making the above effects remarkable, when the projected area S of the first space portion S1 is taken as 1, the projected area S of the molten resin composition supplied to the first space portion S1 A is preferably 0.3 to 0.95, and more preferably 0.4 to 0.9. The above-mentioned projected area S p and the projected area S p The relationship between and the projected area S A For example, it can be realized by appropriately setting the diameter of the first space portion S1 for forming the bottom portion A1 of the press-molded body A to be manufactured and the diameter of the concave portion 32a. For example, if the ratio of the diameter of the first space portion S1 to the diameter of the concave portion 32a is preferably set to 1:0.3 to 0.9, the relationship between the above-mentioned projected area S p and the projected area S A can be realized.

[0061] (Raw material of press-molded body A) In this manufacturing method, the thermoplastic resin contained in the molten resin composition may be any thermoplastic resin as long as the above-mentioned effects are achieved. It is preferable that the thermoplastic resin contains a biodegradable resin as a base resin.

[0062] Furthermore, the biodegradable resin is not particularly limited, and examples thereof include polyhydroxyalkanoate-based resins, polylactic acid, polyglycolic acid, polybutylene succinate, polybutylene succinate adipate, polybutylene adipate terephthalate, polybutylene succinate terephthalate, polycaprolactone, and the like. Among these, the biodegradable resin is preferably a polyhydroxyalkanoate-based resin (hereinafter, may be referred to as a PHA-based resin). In this specification, the "PHA-based resin" is a general term for polymers having hydroxyalkanoic acid as a monomer unit.

[0063] Particularly preferred is a thermoplastic resin, among PHA resins, a poly(3-hydroxyalkanoate) resin (hereinafter sometimes referred to as P3HA resin). In this specification, "P3HA resin" refers to a 3-hydroxyalkanoic acid repeating unit represented by the general formula: [-CHR-CH2-CO-O-] (wherein R is C n H 2n+1 It is a polyhydroxyalkanoate containing an alkyl group represented by , where n is an integer between 1 and 15 (inclusive), as a repeating unit.

[0064] More specifically, P3HA resins preferably contain 3-hydroxybutyrate (3HB) units. Examples of P3HA resins containing 3HB units include poly(3-hydroxybutyrate) (P3HB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P3HB3HV), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P3HB3HH), poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) (P3HB3HV3HH), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), and poly(3-hydroxybutyrate-co-3-hydroxydecanoate).

[0065] As for P3HA resins, P3HA resins produced by microorganisms (microbially produced P3HA resins) are preferred. Microbially produced P3HA resins are usually composed only of D-isomers (R-isomers) of polyhydroxyalkanoate monomer units. Among microbially produced P3HA resins, P3HB, P3HB3HH, P3HB3HV, P3HB3HV3HH, and P3HB4HB are preferred due to their ease of industrial production, and P3HB, P3HB3HH, P3HB3HV, and P3HB4HB are more preferred.

[0066] The microorganisms that produce microbially produced P3HA resins are not particularly limited as long as they are microorganisms capable of producing P3HA resins. For example, the first P3HB-producing bacterium was Bacillus megaterium, discovered in 1925, and other examples include natural microorganisms such as Cupriavidus necator (formerly classified as Alcaligenes eutrophus, Ralstonia eutropha) and Alcaligenes latus. It is known that P3HB accumulates within the cells of these microorganisms.

[0067] Furthermore, known microorganisms that produce copolymers of hydroxybutyrate and other hydroxyalkanoates include Aeromonas caviae, which produces P3HB3HV and P3HB3HH, and Alcaligenes eutrophus, which produces P3HB4HB. In particular, with respect to P3HB3HH, Alcaligenes eutrophus AC32 strain (FERM BP-6038) (T.Fukui, Y.Doi, J.Bateriol., 179, p4821-4830 (1997)), into which genes of the P3HA resin synthase group have been introduced, are more preferred in order to increase the productivity of P3HB3HH. Microbial cells that have accumulated P3HB3HH in their cells by culturing these microorganisms under appropriate conditions are used. In addition to the above, genetically modified microorganisms into which various P3HA resin synthesis-related genes can be introduced can be used, depending on the P3HA resin to be produced, or the culture conditions, including the type of substrate, can be optimized.

[0068] Furthermore, the P3HA resin contains at least one copolymer of 3HB units and other hydroxyalkanoate units, and the 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate) resin are preferably 90.0 to 99.0 mol%, more preferably 91.0 to 98.5 mol%, more preferably 92.0 to 98.5 mol%, and even more preferably 93.0 to 98.0 mol%, of the total repeating units (100 mol%).

[0069] When the composition ratio of 3HB repeating units is 90.0 mol% or higher, the rigidity of the P3HA resin is further improved, the crystallization rate is increased, burrs are reduced, and productivity tends to improve. On the other hand, when the composition ratio of 3HB repeating units is 99.0 mol% or lower, the melting point is below the thermal decomposition temperature, enabling stable and continuous production. The monomer composition ratio of P3HA resin can be measured by gas chromatography, etc. (see, for example, International Publication No. 2014 / 020838).

[0070] The molecular weight of the P3HA resin is not particularly limited, as long as it exhibits substantially sufficient physical properties for the intended application. The weight-average molecular weight range of the P3HA resin is preferably 100,000 to 1,000,000, more preferably 150,000 to 700,000, even more preferably 200,000 to 500,000, and particularly preferably 250,000 to 450,000. A weight-average molecular weight of 100,000 or more provides adequate mechanical strength. Furthermore, a molecular weight of 1,000,000 or less suppresses the increase in melt viscosity and provides excellent moldability.

[0071] The weight-average molecular weight can be determined using gel permeation chromatography (GPC) (Shodex GPC-101, Showa Denko Corporation), with a polystyrene gel column (Shodex K-804, Showa Denko Corporation) and chloroform as the mobile phase, expressed as the molecular weight in polystyrene equivalent. Calibration curves are created using polystyrene with weight-average molecular weights of 31,400, 197,000, 668,000, and 1,920,000. Any column suitable for measuring the aforementioned molecular weights can be used in the GPC.

[0072] The molten resin composition in this manufacturing method may contain a second P3HA-based resin in addition to the P3HA-based resin. The second P3HA-based resin contains at least one copolymer of 3HB units and other hydroxyalkanoate units, and the amount of 3HB units in the poly(3-hydroxyalkanoate)-based resin is preferably 65.0 to 90.0 mol%, more preferably 68.0 to 88.0 mol%, and even more preferably 70.0 to 85.0 mol%, of the total repeating units (100 mol%). The inclusion of the second P3HA-based resin in the molten resin composition results in superior toughness of the molded article.

[0073] The second P3HA-based resin is not particularly limited, as long as it is different from the aforementioned P3HA-based resin. Examples of the second P3HA-based resin include the resins exemplified above as P3HA-based resins.

[0074] The content of the second P3HA resin is not particularly limited, but is preferably 50 parts by weight or less, more preferably 45 parts by weight or less, and even more preferably 40 parts by weight or less, per 100 parts by weight of the total P3HA resin. The lower limit of the content of the second P3HA resin is not particularly limited and may be 0 parts by weight. The P3HA resin described above can be used as the second P3HA resin. In this specification, "total P3HA resin" refers to all P3HA resin contained in the molten resin composition in this manufacturing method.

[0075] The molten resin composition may contain other resins besides P3HA resins, as long as the effects of the present invention are not impaired. Examples of such other resins include aliphatic polyester resins such as polybutylene succinate adipate, polybutylene succinate, polycaprolactone, and polylactic acid, and aliphatic aromatic polyester resins such as polybutylene adipate terephthalate, polybutylene sebatate terephthalate, and polybutylene azelate terephthalate. The other resin may consist of only one type or two or more types.

[0076] The content of the other resins is not particularly limited, but is preferably 50 parts by weight or less, more preferably 40 parts by weight or less, per 100 parts by weight of the total P3HA resin. Even more preferably 30 parts by weight or less. The lower limit of the content of the other resins is not particularly limited and may be 0 parts by weight.

[0077] The molten resin composition does not necessarily have to contain inorganic fillers, but it is preferable that it further contains inorganic fillers. The inclusion of inorganic fillers in the molten resin composition improves the crystallization rate, resulting in effects such as reduced burrs and improved production cycles.

[0078] The inorganic filler is not particularly limited, but examples include talc, diatomaceous earth, white clay, clay, calcium carbonate, manganese carbonate, magnesium carbonate, barium sulfate, mica, silica, alumina, zircon, iron oxide, zinc oxide, titanium oxide, silicon nitride, boron nitride, aluminum nitride, silicon carbide, graphite, carbon black, ferrite, graphite, quartz, glass fiber, and glass particles. These may be used individually or in combination of two or more types.

[0079] The inorganic filler content is, for example, 0 to 60 parts by weight, preferably 5 to 50 parts by weight, more preferably 10 to 40 parts by weight, and particularly preferably 15 to 35 parts by weight, per 100 parts by weight of the total P3HA resin. When the inorganic filler content is within the above range, it is possible to achieve both a sufficient crystallization rate and toughness.

[0080] Furthermore, the molten resin composition may contain additives that can be used together with the P3HA resin, to the extent that they do not impair the effects of the present invention. Examples of such additives include colorants such as pigments and dyes, odor absorbers such as activated carbon and zeolites, fragrances such as vanillin and dextrin, plasticizers, antioxidants, weather-resistant modifiers, ultraviolet absorbers, crystal nucleating agents, lubricants, mold release agents, water repellents, antibacterial agents, and sliding properties modifiers. Only one type of additive may be included, or two or more types may be included. The content of these additives can be appropriately determined by those skilled in the art depending on the intended use.

[0081] [Mold equipment] This mold apparatus is characterized by comprising a pair of molds 30 as shown in Figures 2 and 3. Referring to Figures 2 and 3, in the pair of molds 30 described above, the recess 32a and the protrusion 31a are configured such that the molten resin composition P in the recess 32a flows from the first spatial portion S1 to the second spatial portion S2 by pressing the molten resin composition P in the recess 32a with the protrusion 31a. The features of the protrusion 31a and the recess 32a are as described in the section on [Method for Manufacturing Press-Molded Articles], so a further explanation will be omitted.

[0082] [Manufacturing equipment for press-molded products] The press-formed article manufacturing apparatus according to this embodiment is configured to realize the manufacturing method. The manufacturing apparatus according to this embodiment is configured to include the mold device. Figure 1 is a schematic diagram showing the general configuration of the manufacturing apparatus 10 according to this embodiment. For the sake of explanation, Figure 1 shows only the core mold 32 among the various components of the mold device included in the manufacturing apparatus 10, and the other components are omitted.

[0083] As shown in Figure 1, the manufacturing apparatus 10 includes, in addition to the main mold apparatus, a molten resin generation unit 1 and a supply unit 2.

[0084] The molten resin production unit 1 heats a thermoplastic resin composition to produce a molten resin composition P. The molten resin production unit 1 is equipped with a raw material input section for introducing the raw materials of the thermoplastic resin composition. The molten resin production unit 1 is equipped with a molten kneading device for molten and kneading the raw materials introduced from the raw material input section. The molten resin production unit 1 may also be equipped with a mixing device for mixing the raw materials as needed. The molten kneading device and the mixing device can be exemplified by the equipment described above.

[0085] The supply unit 2 has a discharge unit 2a that discharges the molten resin composition P generated in the molten resin generation unit 1. The discharge unit 2a can be exemplified by the configuration of the discharge unit described above. The supply unit 2 supplies the molten resin composition P between the pair of molds by the discharge unit 2a. In the configuration shown in Figure 1, the supply unit 2 is configured to discharge the molten resin composition P from the discharge unit 2a to the core mold 32. After a predetermined amount of molten resin composition P is supplied to the core mold 32, the cavity mold is placed on the core mold 32, thereby supplying the molten resin composition between the pair of molds.

[0086] Although not shown in Figure 1, the manufacturing apparatus 10 also includes a molding section for performing the molding process described above. This molding section closes a pair of molds, press-moldes a flowable molten resin composition P, and cools it. The molding section includes a hot press molding machine that heat-presses the pair of molds, and a cooling device that cools the pair of molds after the heat-pressing is complete. The hot press machine and the cooling device can be any device used in press molding. For example, the cooling device may include a pair of cooling plates that clamp the pair of molds, and the cooling plates may be used to cool and press the pair of molds.

[0087] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0088] In other words, one embodiment of the present invention is as follows: <1> A method for manufacturing a press-molded body, comprising supplying a fluid molten resin composition containing a thermoplastic resin to a pair of molds consisting of a core mold and a cavity mold, wherein the pair of molds comprises a first space portion for forming the bottom portion of the press-molded body and a second space portion for forming the side wall portion of the press-molded body, and in the first space portion, the core mold has a recess formed on the surface for forming the inner bottom surface of the press-molded body, and the cavity mold has a protrusion formed on the surface for forming the outer bottom surface of the press-molded body that is sized to fit into the recess, and the method for manufacturing a press-molded body includes a resin supply step of filling the recess of the core mold with the molten resin composition, and a molding step of closing the pair of molds and press-molding the molten resin composition, wherein the molding step includes a flow step of pressing the molten resin composition in the recess with the protrusion to cause the molten resin composition to flow from the first space portion to the second space portion. <2> The ratio of the length of the side wall portion of the press-formed body to the diameter of the bottom portion of the press-formed body is 1.0 to 5.0. <1> A method for manufacturing a press-molded body. <3> The wall thickness of the aforementioned press-formed body is 0.1 mm to 0.5 mm. <1> or <2> A method for manufacturing a press-molded body. <4> The depth of the recess is 3.0 mm to 9.0 mm. <1> ~ <3> A method for manufacturing a press-molded body. <5> In the pair of molds prior to the molding process, the projected area of ​​the molten resin composition supplied to the first space portion, as viewed from the cavity mold side, is 0.3 to 0.95, where the projected area of ​​the first space portion is 1. <1> ~ <4> A method for manufacturing a press-molded body. <6> The aforementioned thermoplastic resin is a poly(3-hydroxyalkanoate) resin. <1> ~ <5> A method for manufacturing a press-molded body. <7> A mold apparatus for manufacturing a rotationally symmetrical bottomed cylindrical press-molded body, comprising a pair of molds consisting of a core mold and a cavity mold, wherein a fluid molten resin composition containing a thermoplastic resin is supplied to the pair of molds, the pair of molds comprising a first spatial portion for forming the bottom of the press-molded body and a second spatial portion for forming the side wall portion of the press-molded body, wherein in the first spatial portion, the core mold has a recess formed on the surface that forms the inner bottom surface of the press-molded body, which is a portion for containing the molten resin composition, and the cavity mold has a protrusion formed on the surface that forms the outer bottom surface of the press-molded body, which is sized to fit into the recess, and the recess and the protrusion are configured such that the molten resin composition in the recess flows from the first spatial portion to the second spatial portion by pressing the molten resin composition in the recess with the protrusion. <8> <7> A press-molded body manufacturing apparatus equipped with a mold device. [Examples]

[0089] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0090] [Example 1] (Press forming) Using a miniature injection molding machine, Moldlock (manufactured by Shibata Precision Co., Ltd.), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (sometimes referred to as P3HB3HH) (weight-average molecular weight Mw 400,000, 3HH ratio 6 mol%) was heated to 160°C to form a molten resin. The molten P3HB3HH resin was then dispensed into a lower mold preheated to 150°C, supplying it to the lower mold (core mold). Next, the lower mold containing the P3HB3HH resin was closed with an upper mold (cavity mold), also heated to 150°C, thereby supplying molten resin between the pair of molds. The pair of molds containing the P3HB3HH resin were then subjected to hot pressing using a hot press molding device (Mikado Technos Co., Ltd., VS38-2525) at a press pressure of 125 KN for 20 seconds. The pair of molds, which had just been heat-pressed, were immediately sandwiched between upper and lower cooling plates heated to 25°C, and press molding was performed by cooling press at a press pressure of 30KN for 300 seconds. After press molding, the molds were opened and the molded product was removed.

[0091] (Mold) To manufacture a rotationally symmetrical, bottomed cylindrical press-formed body, a pair of molds consisting of a core mold and a cavity mold was used. The pair of molds comprises a first space portion for forming the bottom of the press-formed body and a second space portion for forming the side walls of the press-formed body. Here, aluminum alloy (A7075) was used as the mold material for both the core mold and the cavity mold. In the pair of molds, the core mold has a recess formed on the surface that forms the inner bottom surface of the press-formed body, and the cavity mold has a protrusion formed on the surface that forms the outer bottom surface of the press-formed body, which is sized to fit into the recess.

[0092] The depth of the recess in the core type and the height of the protrusion in the cavity type were both set to 3 mm, and a press-molded body was manufactured according to the (press molding) method described above.

[0093] [Example 2] A press-molded body was manufactured in the same manner as in Example 1, except that the depth of the recess in the core type and the height of the protrusion in the cavity type were both set to 6 mm.

[0094] [Example 3] A press-molded body was manufactured in the same manner as in Example 1, except that the depth of the recess in the core type and the height of the protrusion in the cavity type were both set to 9 mm.

[0095] [Comparative Example 1] A press-molded body was manufactured in the same manner as in Example 1, except that the depth of the recess in the core type and the height of the protrusion in the cavity type were both set to 1 mm.

[0096] (Evaluation method) <Evaluation of hole occurrence> The side surfaces of the press-molded products in Examples 1, 2, and 3, and Comparative Example 1, were visually inspected to determine whether or not holes had occurred in the side walls, and evaluated as follows. Good: No holes, Unacceptable: It has holes.

[0097] The evaluation results are shown in Table 1.

[0098] [Table 1]

[0099] Regarding the evaluation results for bubble generation, as is clear from the results shown in Table 1, the press-molded article of Comparative Example 1 had holes in the sidewall and was in an incomplete state. On the other hand, the press-molded articles of Examples 1, 2, and 3 did not show holes in the sidewall and had a good appearance. [Industrial applicability]

[0100] The present invention can be suitably used in the field of manufacturing press-molded articles using thermoplastic resins, particularly P3HA-based resins, and in other fields. [Explanation of Symbols]

[0101] 1. Molten resin generation section 2 Supply section 2a Discharge part 10. Manufacturing equipment (machinery for manufacturing press-formed products) 30 pairs of molds 31 Cavity type 31a Convex part 32-core type 32a Recess A Press-formed body A1 bottom A11 Inner bottom surface A12 Outer bottom A2 opening A3 depression A4 side wall S1 1st spatial part S2 2nd spatial part S p Projected area S A Projected area

Claims

1. A method for manufacturing a press-molded body, comprising supplying a fluid molten resin composition containing a thermoplastic resin to a pair of molds consisting of a core mold and a cavity mold, wherein a rotationally symmetrical bottomed cylindrical press-molded body is produced. The pair of molds are A first space portion for forming the bottom of the press-formed body, It comprises a second space portion for forming the side wall portion of the press-formed body, In the first spatial portion, The core mold has a recess formed on the surface that forms the inner bottom surface of the press-formed body. The cavity mold has a protrusion formed on the surface that forms the outer bottom surface of the press-formed body, which is sized to fit into the recess. A resin supply step of filling the recess of the core type with the molten resin composition, The process includes closing the pair of molds and press-molding the molten resin composition, A method for manufacturing a press-molded article, wherein the molding step includes a flow step in which the molten resin composition in the recess is pressed by the protrusion, thereby causing the molten resin composition to flow from the first space to the second space.

2. The method for manufacturing a press-formed body according to claim 1, wherein the ratio of the length of the side wall portion of the press-formed body to the diameter of the bottom portion of the press-formed body is 1.0 to 5.

0.

3. The method for manufacturing a press-formed article according to claim 1 or 2, wherein the wall thickness of the press-formed article is 0.1 mm to 0.5 mm.

4. The method for manufacturing a press-molded article according to claim 1 or 2, wherein the depth of the recess is 3.0 mm to 9.0 mm.

5. The method for manufacturing a press-molded article according to claim 1 or 2, wherein, in the pair of molds prior to the molding process, the projected area of ​​the molten resin composition supplied to the first space portion, as viewed from the cavity mold side, is 0.3 to 0.95 when the projected area of ​​the first space portion is set to 1.

6. The method for producing a press-molded article according to claim 1 or 2, wherein the thermoplastic resin is a poly(3-hydroxyalkanoate) resin.

7. A mold apparatus comprising a pair of molds consisting of a core mold and a cavity mold, for supplying a fluid molten resin composition containing a thermoplastic resin to the pair of molds to manufacture a rotationally symmetrical bottomed cylindrical press-molded body, The pair of molds are A first space portion for forming the bottom of the press-formed body, It comprises a second space portion for forming the side wall portion of the press-formed body, In the first spatial portion, The core mold has a recess formed on the surface that forms the inner bottom surface of the press-molded body, which is a portion for containing the molten resin composition. The cavity mold has a protrusion formed on the surface that forms the outer bottom surface of the press-formed body, which is sized to fit into the recess. A mold apparatus in which the recess and the protrusion are configured such that the molten resin composition in the recess flows from the first spatial portion to the second spatial portion by pressing the molten resin composition in the recess with the protrusion.

8. A press-formed article manufacturing apparatus comprising the mold apparatus described in claim 7.

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