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

Abstract

In the production of a press-molded article using a fluid molten resin composition as the molding material, the generation of air bubbles in the sidewall portion of the resulting molded article is suppressed. [Solution] The method for manufacturing a press-molded body involves using a pair of molds (30) in which the burr molding channel (R3) of the third spatial portion (S3) has a first channel (R31) that extends in a direction parallel to the compression direction (HD direction) of the pair of molds, the width of the first channel (R31) is 0.03 mm to 0.1 mm, and the length of the first channel (R31) is 1.0 mm or more, and the length of the first channel (R31) is one-third or less of the length of the side wall portion of the press-molded body, and includes a molding step of closing the pair of molds (30) and filling the space from the first spatial portion (S1) to the third spatial portion (S3) with a molten resin composition and press-molding.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a press-formed body, a mold device, and a manufacturing device.

Background Art

[0002] Techniques for manufacturing a molded body containing a thermoplastic resin by press molding are disclosed, for example, in Patent Document 1.

[0003] Patent Document 1 discloses a method for manufacturing a metal resin composite by press molding a metal member and a resin material. In this method, as a pair of molds, an upper mold and a lower mold provided with a cavity for arranging the resin material are used. Then, the metal member and the resin material are sandwiched between the upper mold and the lower mold. And the resin material leaking from the cavity is collected in a recess provided in the upper mold.

[0004] In addition to the technique disclosed in Patent Document 1, a technique using a fluid molten resin composition obtained by heating a thermoplastic resin as a molding material is also known. In this technique, after injecting the molten resin composition between a pair of molds, the pair of molds are closed, press-molded, and cooled to obtain a molded body.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] When a molded body (for example, a cup) having a bottom portion and a side wall portion is press-molded using a fluid molten resin composition as a molding material, if the flow path of the molten resin composition is long in the space portion for forming the side wall portion, it has been found that air bubbles are generated in the side wall portion of the obtained molded body, and there is room for improvement in terms of aesthetics.

[0007] One aspect of the present invention aims to realize a method for manufacturing a press-molded article, a mold apparatus, and a manufacturing apparatus that can suppress the generation of air bubbles in the side walls of the resulting molded article, even when using a pair of molds with long flow paths for the molten resin composition in the space portion for molding the side walls. [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 having a bottom and side walls 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 ratio of the length of the bottom to the length of the side walls is 1.0 to 5.0, and the pair of molds comprises a first space portion for forming the bottom of the press-molded article, a second space portion for forming the side walls of the press-molded article, and a third space portion for forming a burr at the end of the side walls. The apparatus comprises a resin supply step of supplying the molten resin composition to the first space portion of the pair of molds, wherein the flow path of the molten resin composition in the third space portion has a first flow path extending in a direction parallel to the compression direction of the pair of molds, and the apparatus comprises a molding step of closing the pair of molds and filling the molten resin composition from the first space portion to the third space portion with the molten resin composition for press molding, wherein the width of the first flow path is 0.03 mm to 0.1 mm, the length of the first flow path is 1.0 mm or more, and the length of the side wall portion is one-third or less.

[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 press-molded body having a bottom and side walls by supplying a fluid molten resin composition containing a thermoplastic resin to the pair of molds, wherein the ratio of the length of the bottom to the length of the side walls is 1.0 to 5.0, the pair of molds comprises a first space portion for forming the bottom of the press-molded body, a second space portion for forming the side walls of the press-molded body, and a third space portion for forming burrs at the end of the side walls, the molten resin composition is supplied to the first space portion, the flow path of the molten resin composition in the third space portion has a first flow path extending parallel to the compression direction of the pair of molds, the width of the first flow path is 0.03 mm to 0.1 mm, the length of the first flow path is 1.0 mm or more, and the length is one-third or less of the length of the side walls. [Effects of the Invention]

[0010] According to one aspect of the present invention, the generation of air bubbles in the side wall portion of the obtained molded article can be suppressed. [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] This 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. [Figure 3] 301 is a cross-sectional view showing the relationship between a press-formed body and a pair of molds used in a method for manufacturing a press-formed body according to an embodiment of the present invention, and 302 is a cross-sectional view showing the schematic configuration of a press-formed body press-formed by the pair of molds shown in 301. [Figure 4] This is a cross-sectional view illustrating the dimensions of the bottom and side walls of a press-formed body suitable for a press-formed body manufacturing method according to an embodiment of the present invention. [Figure 5] This is a schematic cross-sectional view showing the structure of a mold corresponding to a comparative example. [Figure 6]601 is a cross-sectional view showing the relationship between a press-formed body and a pair of molds of Modification 1 used in a method for manufacturing a press-formed body according to an embodiment of the present invention, and 602 is a cross-sectional view showing the schematic configuration of a press-formed body press-formed by the pair of molds shown in 601. [Figure 7] 701 is a cross-sectional view showing the relationship between a press-formed body and a pair of molds of Modification 2 used in a method for manufacturing a press-formed body according to an embodiment of the present invention, and 702 is a cross-sectional view showing the schematic configuration of a press-formed body press-formed by the pair of molds shown in 701. [Figure 8] 801 is a cross-sectional view showing the relationship between a press-formed body and a pair of molds of Modification 3 used in a method for manufacturing a press-formed body according to an embodiment of the present invention, and 802 is a cross-sectional view showing the schematic configuration of a press-formed body press-formed by the pair of molds shown in 801. [Modes for carrying out the invention]

[0012] One embodiment of the present invention will be described in detail below. Unless otherwise specified in this specification, "A to B" representing a numerical range means "greater than or equal to A and less than or equal to B". Furthermore, all references cited in this specification are incorporated herein by reference.

[0013] [Summary of the Invention] The present inventors, when press molding a thermoplastic resin, have adopted method B, in which a molten resin obtained by heating the thermoplastic resin is press molded in a flowable molten state within a pair of molds consisting of a core mold and a cavity mold, rather than method A, in which a sheet-like material made of thermoplastic resin is press molded using a pair of molds consisting of a core mold and a cavity mold. Method A corresponds to the methods disclosed in Patent Documents 1 and 2. Furthermore, method B is particularly effective when using a biodegradable resin such as a poly(3-hydroxyalkanoate) resin as the thermoplastic resin.

[0014] In the production of the press-formed body 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 formed body is higher than that of Method A using a sheet-like material.

[0015] Particularly, for example, when press-forming a rotationally symmetric bottomed cylindrical formed body such as a cup, the following steps (1) and (2) can be adopted to fill the molten resin composition into a pair of molds. (1) Supply the molten resin composition to the space portion (the first space portion) for forming the bottom of the press-formed body 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-formed body, through the space portion for forming the side wall portion of the press-formed body (the second space portion), to the space portion for forming a burr at the end portion of the side wall portion (the third space portion).

[0016] According to the verification by the present inventor, when the molten resin composition is filled into a pair of molds by the above steps (1) and (2) and press-formed, it was found that when the flow path of the molten resin composition is long in the space portion for forming the side wall portion, air bubbles occur in the side wall portion of the obtained formed body. And particularly, when manufacturing a thin-walled press-formed body having a wall thickness of, for example, 0.3 mm, such air bubbles are likely to occur.

[0017] And the present inventor considered that the generation of air bubbles in the side wall portion of the press-formed body is caused by the internal pressure (the pressure of the molten resin composition) in the space portion for forming the side wall portion of the press-formed body when performing the above (2). Then, the present inventor hypothesized that increasing the internal pressure in the space portion for forming the side wall portion of the press-formed body in the above (2) would lead to suppression of the generation of air bubbles in the side wall portion of the press-formed body.

[0018] Based on this hypothesis, the inventors diligently investigated measures to increase the internal pressure of the space where the side wall portion of the press-molded body is formed in (2) above. As a result, they focused on the structure of the space where a burr is formed at the end of the side wall portion of the press-molded body in a pair of molds, and found that by providing a first flow path in the space portion as a flow path for the molten resin composition, extending in the same direction as the compression direction of the pair of molds, and further setting the width and length of the first flow path to a specific range, it is possible to suppress the generation of bubbles in the side wall portion of the resulting molded body, leading to one embodiment of the present invention.

[0019] In other words, a method for manufacturing a press-molded article according to one embodiment of the present invention (hereinafter sometimes referred to as "this manufacturing method") is a method for manufacturing a press-molded article having a bottom portion and side walls 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. The press-molded article has a ratio of the length of the bottom portion to the length of the side walls of 1.0 to 5.0. The pair of molds comprises a first space portion for forming the bottom portion of the press-molded article, a second space portion for forming the side walls of the press-molded article, and a third space portion for forming a burr at the end of the side walls. The flow path of the molten resin composition in the third space portion has a first flow path that extends in the same direction as the compression direction of the pair of molds. The present manufacturing method includes a resin supply step of supplying the molten resin composition to the first spatial portion of the pair of molds, and a molding step of closing the pair of molds and filling the molten resin composition from the first spatial portion to the third spatial portion with the molten resin composition and press molding, wherein the width of the first channel is 0.03 mm to 0.1 mm, the length of the first channel is 1.0 mm or more, and the length is one-third or less of the length of the side wall portion.

[0020] Furthermore, a mold apparatus according to one embodiment of the present invention (hereinafter sometimes referred to as "this mold apparatus") comprises a pair of molds consisting of a core mold and a cavity mold, and is a mold apparatus for manufacturing a press-molded body having a bottom and side walls by supplying a fluid molten resin composition containing a thermoplastic resin to the pair of molds, wherein the ratio of the length of the bottom to the length of the side walls is 1.0 to 5.0, the pair of molds comprises a first space portion for forming the bottom of the press-molded body, a second space portion for forming the side walls of the press-molded body, and a third space portion for forming burrs at the end of the side walls, the molten resin composition is supplied to the first space portion, the flow path of the molten resin composition in the third space portion has a first flow path extending parallel to the compression direction of the pair of molds, the width of the first flow path is 0.03 mm to 0.1 mm, the length of the first flow path is 1.0 mm or more, and the length is one-third or less of the length of the side walls.

[0021] 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.

[0022] [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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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 core mold, and then place the cavity mold on the core mold to supply the molten resin composition between the pair of molds.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] Herein, the manufacturing method is characterized by the structure of the pair of molds that supply the molten resin composition. Figure 2 is a cross-sectional view showing the schematic configuration of the pair of molds 30 used in this manufacturing method. Figure 301 is a cross-sectional view showing the relationship between the press-molded body A and the pair of molds 30, and Figure 302 is a cross-sectional view showing the schematic configuration of the press-molded body A that has been press-molded by the pair of molds 30 shown in Figure 301.

[0040] First, the structure of the press-formed article A manufactured by this manufacturing method will be described. The press-formed article A that can be manufactured by this manufacturing method is not particularly limited as long as it has a bottom and side walls, and examples include U-shaped grooved articles and bottomed cylindrical articles.

[0041] Particularly preferred is that the press-molded body A is a rotationally symmetric, bottomed cylindrical article. Below, a rotationally symmetric, bottomed cylindrical press-molded body A that can be manufactured by this manufacturing method will be described. As shown in 302 of Figure 3, the press-molded body A is a rotationally symmetric, bottomed cylindrical shape. The press-molded body A is cylindrical with a side wall A3, with a bottom A1 formed at one end and an opening A2 at the other end. In addition, a burr A4 is formed on the side of the side wall A3 opposite to the bottom A1, i.e., the end of the press-molded body A on the opening A2 side. The burr A4 is the part that is removed when the press-molded body A is manufactured into a product. The press-molded body A is, 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 1.0 mm, and more preferably 0.2 mm to 0.4 mm.

[0043] Furthermore, in a press-formed body A to which this manufacturing method can be applied, examples of the rotationally symmetrical bottomed cylinder shape include a bottomed regular polygonal prism cylinder shape, a bottomed cylindrical shape, and so on. Examples of bottomed regular polygonal prism cylinder shapes include a bottomed regular triangular prism cylinder shape, a bottomed regular hexagonal prism cylinder shape, and so on.

[0044] Furthermore, the direction in which the side wall portion A3 of the press-formed body A to which this manufacturing method can be applied is not particularly limited. The side wall portion A3 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 cavity mold 31 and core mold 32 of the mold 30 have molding surfaces formed to match the shape of the press-formed body A. The mold 30 has a molding space formed by these molding surfaces. These molding surfaces are formed rotationally symmetric with respect to the axis of symmetry X. In the drawings of this application (Figures 1 to 8), 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). One side (upper side) of the HD direction is defined as the HDa side, and the other side (lower side) is defined as the HDb side. The WD direction can be said to be the radial direction of the rotationally symmetric shape formed by the molding surface. The HD direction is parallel to the direction in which the pair of molds 30 are opened, and to the direction in which the pair of molds 30 are compressed.

[0046] As shown in Figure 2, 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, a second spatial portion S2, and a third spatial portion S3 as the molding space for the press-formed body A. In the molding space of the mold 30, the first spatial portion S1 is a molding space for forming the bottom portion A1 of the press-formed body A, the second spatial portion S2 is a molding space for forming the side wall portion A3 of the press-formed body A, and the third spatial portion S3 is a molding space for forming the burrs A4 of the press-formed body A.

[0047] Furthermore, in the first spatial portion S1, the mold 30 has a bottom molding channel R1, which is a channel for the molten resin composition. In the second spatial portion S2, the mold 30 has a side wall molding channel R2, which is a channel for the molten resin composition. The side wall molding channel R2 is connected to the bottom molding channel R1. Furthermore, in the third spatial portion S3, the mold 30 has a burr molding channel R3, which is a channel for the molten resin composition. The burr molding channel R3 is connected to the end portion of the side wall molding channel R2. The bottom molding channel R1, the side wall molding channel R2, and the burr molding channel R3 are formed by the cavity mold 31 and the core mold 32, respectively. In addition, the bottom molding channel R1, the side wall molding channel R2, and the burr molding channel R3 have shapes that are rotationally symmetric with respect to the axis of symmetry X.

[0048] Here, the burr forming channel R3 in the third spatial portion S3 of the mold 30 has a first channel R31 extending in a direction parallel to the compression direction of the mold 30 (i.e., the HD direction) and a second channel R32 extending in a direction different from the compression direction of the mold 30. The second channel R32 extends in a direction different from the first channel R31, specifically in the WD direction. The first channel R31 is connected to the end portion of the side wall forming channel R2 of the second spatial portion S2, and the second channel R32 is connected to the first channel R31. In the cross-sectional shape along the axis of symmetry X shown in Figure 2, the first channel R31 and the second channel R32 form an L-shape.

[0049] As shown in 301 of Figure 3, in the third spatial portion S3 of the mold 30, the first flow path R31 is formed by the molding surface R31a of the cavity mold 31 and the molding surface R31b of the core mold 32. Both molding surfaces R31a and R31b extend in the HD direction. The second flow path R32 is formed by the molding surface R32a of the cavity mold 31 and the molding surface R32b of the core mold 32. Both molding surfaces R32a and R32b extend in the WD direction.

[0050] In this manufacturing method, the resin supply step involves supplying the molten resin composition to the first spatial portion S1 of the pair of molds 30. In this resin supply step, the amount of molten resin composition supplied to the first spatial portion S1 should be such that the molten resin composition 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 first spatial portion S1, the characteristics of the molten resin composition, the size of the side wall molding channel R2 in the second spatial portion S2, etc.

[0051] 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. In this manufacturing method, in the molding process described above, the molten resin composition is flowed from the first spatial portion S1 to the third spatial portion S3. That is, in the molding process described above, the molten resin composition flows in the order of the bottom molding channel R1 and the side wall molding channel R2. When the molten resin composition reaches the end of the side wall molding channel R2, it flows into the burr molding channel R3 and remains within the burr molding channel R3.

[0052] As shown in Figure 3, 302, the press-formed body A formed by the above molding process has a burr A4 extending from the end of the side wall portion A3. The shape of the burr A4 follows the shape of the burr forming channel R3 of the mold 30.

[0053] Figure 4 is a cross-sectional view illustrating the dimensions of the bottom A1 and side wall A3 of a press-molded body A suitable for this manufacturing method. In a press-molded body A suitable for this manufacturing method, the length C of the side wall A3 is greater than or equal to the length B of the bottom A1, and the ratio of the length B of the bottom A1 to the length C of the side wall A3 is 1.0 to 5.0, preferably 1.0 to 3.0. If this manufacturing method is applied to the production of a press-molded body A in which the ratio of the length C of the side wall A3 to the length B of the bottom A1 is within the above numerical range, the bubble suppression effect of the side wall A3 becomes significant.

[0054] Here, the length 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 makes up the outer shape of the base A1. For example, if the press-formed body A is cylindrical, the length B of the base A1 refers to the diameter of the circle that makes up the outer shape of the base A1. Also, if the press-formed body A is a rectangular prism, the length B of the base A1 refers to the length of the diagonal of the square that makes up the outer shape of the base A1.

[0055] Here, as shown in 301 of Figures 2 and 3, this manufacturing method is characterized by the structure of the burr forming channel R3 in the third spatial portion S3 of the mold 30. Specifically, in this manufacturing method, the burr forming channel R3 is characterized by having a first channel R31 that extends in a direction parallel to the compression direction of the mold 30. This has the effect of suppressing the generation of air bubbles in the side wall portion A3 of the obtained press-molded body A. The term "direction parallel to the compression direction of the mold 30" here includes directions that are substantially parallel to the compression direction of the mold 30. Specifically, "direction parallel to the compression direction of the mold 30" is a direction in which the angle with respect to the compression direction of the mold 30 is between 0° and 5°.

[0056] Figure 5 is a schematic cross-sectional view showing the structure of a mold corresponding to a comparative example of this manufacturing method. In the mold shown in Figure 5, in the third spatial portion S3, the burr forming channel does not have a first channel extending in a direction parallel to the compression direction of the mold (i.e., the HD direction), but has a second channel extending in the WD direction. This second channel is formed by the molding surface R32a' of the cavity mold 31 and the molding surface R33b' of the core mold 32. Both the molding surface R32a' and the molding surface R33b' extend in the WD direction.

[0057] The mold shown in Figure 5 lacks a first flow path extending parallel to the compression direction of the mold in the burr molding flow path, which is the final filling portion of the molten resin composition. Therefore, when the above molding process is performed using the mold shown in Figure 5, the force due to the compression of the mold is not easily transmitted to the molten resin composition in the third space portion S3, and the molten resin composition does not easily flow through the burr molding flow path. As a result, when a press-molded body A is manufactured in which the ratio of the length B of the bottom portion A1 to the length C of the side wall portion A3 is 1.0 to 5.0, the force due to the compression of the mold does not reach the end portion of the side wall molding flow path during the above molding process, and therefore the internal pressure cannot be maintained at a high level up to the end portion of the side wall molding flow path. Consequently, it may not be possible to suppress the generation of bubbles in the side wall portion A3 of the obtained press-molded body A.

[0058] On the other hand, as shown in 301 of Figures 2 and 3, in this manufacturing method, the burr molding channel R3 has a first channel R31 that extends in a direction parallel to the compression direction of the mold 30. Therefore, when the above molding process is performed, in the third space portion S3, the force due to the compression of the mold is more easily applied to the molten resin composition in the first channel R31. As the molten resin composition passes through the first channel R31, the molten resin composition in the side wall molding channel R2 is compressed, and the resin density increases. During the above molding process, the force due to the compression of the mold is sufficiently transmitted to the end portion of the side wall molding channel R2, so that the internal pressure can be maintained at a high level up to the end portion of the side wall molding channel R2. As a result, this manufacturing method has the effect of suppressing the generation of bubbles in the side wall portion A3 of the obtained press-molded body A.

[0059] Furthermore, in order to maintain a high internal pressure all the way to the end of the side wall molding channel R2, this manufacturing method is characterized by the dimensions of the first channel R31 of the burr molding channel R3. In this manufacturing method, the width of the first channel R31 is 0.03 mm to 0.1 mm, and preferably 0.03 mm to 0.06 mm. The width of the first channel R31 here refers to the distance between the molding surfaces R31a and R31b formed by the first channel R31. The length of the first channel R31 is 1.0 mm or more, and preferably 3.0 mm or more. The length of the first channel R31 is also preferably one-third or less of the length C of the side wall A3, and preferably one-sixth or less of the length C of the side wall A3. As described above, the upper limit of the length of the first channel R31 can be appropriately set according to the length C of the side wall A3. The dimensions of the first flow path R31 are defined as described above, which has the effect of suppressing the generation of air bubbles in the side wall portion A3 of the resulting press-molded body A.

[0060] In the above description, during the molding process, the mold 30 was arranged with the cavity mold 31 on the HDa side and the core mold 32 on the HDb side, as shown in 301 of Figure 3. However, the arrangement of the mold 30 during the molding process is not limited to the arrangement shown in 301 of Figure 3, as long as it allows the molten resin composition to flow into the third spatial portion S3. In the molding process of this manufacturing method, the pair of molds 30 may be closed with the cavity mold 31 on the HDb side and the core mold 32 on the HDa side. From the viewpoint of the ease with which the molten resin composition flows into the third spatial portion S3, it is preferable to close the pair of molds 30 with the cavity mold 31 on the HDa side and the core mold 32 on the HDb side, as shown in 301 of Figure 3.

[0061] (Variation 1) In the configuration of the pair of molds 30 used in this manufacturing method, other variations of the configuration shown in Figure 3, 301 will be described. Figure 6, 601 is a cross-sectional view showing the relationship between the pair of molds 30A and the press-formed body A as this variation 1, and Figure 6, 602 is a cross-sectional view showing the schematic configuration of the press-formed body A that has been press-formed by the pair of molds 30A shown in Figure 6, 601.

[0062] As shown in 601 of Figure 6, in the mold 30A, the burr forming channel of the third spatial portion S3 may be configured in which a plurality of first channels and second channels are connected. In the burr forming channel of the mold 30A, the first channel is a first channel (hereinafter referred to as the first channel Y1) formed by the molding surface R31c of the cavity mold 31A and the molding surface R31d of the core mold 32A, and a first channel (hereinafter referred to as the first channel Y2) formed by the molding surface R31e of the cavity mold 31A and the molding surface R31f of the core mold 32A. Furthermore, the second flow path consists of a second flow path (hereinafter referred to as the second flow path X1) formed by the molding surface R32c of the cavity mold 31A and the molding surface R32d of the core mold 32A, a second flow path (hereinafter referred to as the second flow path X2) formed by the molding surface R32e of the cavity mold 31A and the molding surface R32f of the core mold 32A, and a second flow path (hereinafter referred to as the second flow path X3) formed by the molding surface R32g of the cavity mold 31A and the molding surface R32h of the core mold 32A.

[0063] A second flow channel X1 is connected to the end portion of the side wall molding flow channel, and the first flow channel Y1, second flow channel X2, first flow channel Y2, and second flow channel X3 are connected to the second flow channel X1 in the WD direction (towards the opposite side of the end portion of the side wall molding flow channel) in this order. In the axial cross-sectional shape shown at 601 in Figure 6, the third space portion S3 of the mold 30A is formed by the second flow channel X1, first flow channel Y1, second flow channel X2, first flow channel Y2, and second flow channel X3 to form an inverted U shape. Accordingly, as shown at 602 in Figure 6, the burr A4a of the resulting press-molded body A has an inverted U-shaped cross-sectional shape.

[0064] Even with this manufacturing method using the mold 30A of Modification 1, the effect of suppressing bubble generation in the side wall portion A3 of the obtained press-molded body A is achieved.

[0065] (Modification 2) In the configuration of the pair of molds 30 used in this manufacturing method, further variations of the configuration shown in 301 of Figure 3 will be described. 701 of Figure 7 is a cross-sectional view showing the relationship between the pair of molds 30B, which is this variation 2, and the press-formed body A, and 702 of Figure 7 is a cross-sectional view showing the schematic configuration of the press-formed body A press-formed by the pair of molds 30B shown in 701 of Figure 7.

[0066] In the burr forming channel of mold 30B shown at 701 in Figure 7, the first channel is a first channel (hereinafter referred to as the first channel Y3) formed by the molding surface R31g of cavity mold 31B and the molding surface R31h of core mold 32B. The second channel consists of a second channel (hereinafter referred to as the second channel X3) formed by the molding surface R32i of cavity mold 31B and the molding surface R32j of core mold 32B, and a second channel (hereinafter referred to as the second channel X4) formed by the molding surface R32k of cavity mold 31B and the molding surface R32l of core mold 32B.

[0067] A second flow channel X3 is connected to the end portion of the side wall molding flow channel, and a first flow channel Y3 and a second flow channel X4 are connected to the second flow channel X3 in the WD direction (towards the opposite side of the end portion of the side wall molding flow channel) in this order. In the axial cross-sectional shape shown at 701 in Figure 7, the burr forming flow channel of the third space portion S3 of the mold 30A has an L-shaped flow channel formed by the first flow channel Y3 and the second flow channel X4. The burr forming flow channel is configured such that the L-shaped flow channel and the end portion of the side wall molding flow channel are connected via the second flow channel X3. As shown at 702 in Figure 7, the burr A4b of the obtained press-molded body A is formed to match the shape of this burr forming flow channel.

[0068] Even with this manufacturing method using the mold 30B of Modified Example 2, the effect of suppressing bubble generation in the side wall portion A3 of the obtained press-molded body A is achieved.

[0069] (Variation 3) In the configuration of the pair of molds 30 used in this manufacturing method, further variations of the configuration shown in 301 of Figure 3 will be described. 801 of Figure 8 is a cross-sectional view showing the relationship between the pair of molds 30C, which is this third variation, and the press-formed body A, and 802 of Figure 8 is a cross-sectional view showing the schematic configuration of the press-formed body A press-formed by the pair of molds 30C shown in 801 of Figure 8.

[0070] The burr forming channel of the mold 30C shown at 801 in Figure 8 has a first channel and no second channel. In this burr forming channel, the first channel is a first channel (hereinafter referred to as the first channel Y4) formed by the molding surface R31i of the cavity mold 31C and the molding surface R31j of the core mold 32C.

[0071] The first flow channel Y4 is connected from the HDb side of the end portion of the side wall molding channel. As shown in 802 of Figure 8, the burr A4c of the resulting press-molded body A is formed to match this burr molding channel.

[0072] Even with this manufacturing method using the mold 30C of Modified Example 3, the effect of suppressing bubble generation in the side wall portion A3 of the obtained press-molded body A is achieved.

[0073] (Raw materials for 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 it provides the effects described above. Preferably, the thermoplastic resin contains a biodegradable resin as the base resin.

[0074] Furthermore, the biodegradable resin is not particularly limited, but examples include polyhydroxyalkanoic acid 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 polyhydroxyalkanoic acid resin (hereinafter sometimes referred to as a PHA resin). In this specification, "PHA resin" is a general term for polymers having hydroxyalkanoic acid as a monomer unit.

[0075] 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.

[0076] 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).

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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%).

[0081] 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).

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] [Mold equipment] This mold apparatus is characterized by comprising a pair of molds 30 as shown in 301 of Figures 2 and 3. Referring to 301 of Figures 2 and 3, in the pair of molds 30 described above, the flow path of the molten resin composition in the third spatial portion S3, i.e., the deburring flow path R3, has a first flow path R31 that extends parallel to the compression direction of the pair of molds 30. From the above description, the width of the first flow path R31 is 0.03 mm to 0.1 mm, the length of the first flow path R31 is 1.0 mm or more, and is one-third or less of the length of the side wall portion A3. Other features of the pair of molds 30 are as described in the section on [Method for Manufacturing Press-Molded Articles], so the description is omitted here. This mold apparatus may also comprise the pair of molds 30A, 30B, or 30C described above.

[0094] [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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] In other words, one embodiment of the present invention is as follows: <1> A method for manufacturing a press-formed body having a bottom and side walls, 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 press-formed body has a ratio of the length of the bottom to the length of the side walls of 1.0 to 5.0, and the pair of molds comprises a first space portion for forming the bottom of the press-formed body, a second space portion for forming the side walls of the press-formed body, and a third space portion for forming a burr at the end of the side walls, wherein in the third space portion A method for manufacturing a press-molded article, comprising: a resin supply step of supplying the molten resin composition to the first spatial portion of the pair of molds, wherein the flow path of the molten resin composition has a first flow path extending in a direction parallel to the compression direction of a pair of molds; and a molding step of closing the pair of molds and filling the molten resin composition from the first spatial portion to the third spatial portion with the molten resin composition for press molding, wherein the width of the first flow path is 0.03 mm to 0.1 mm, and the length of the first flow path is 1.0 mm or more and less than or equal to one-third of the length of the side wall portion. <2> The flow path of the molten resin composition in the third spatial portion comprises the first flow path and the second flow path extending in a direction different from the compression direction of the pair of molds. <1> A method for manufacturing a press-molded body. <3> The aforementioned thermoplastic resin is a poly(3-hydroxyalkanoate) resin. <1> or <2> A method for manufacturing a press-molded body. <4> A mold apparatus comprising a pair of molds consisting of a core mold and a cavity mold, for manufacturing a press-molded body having a bottom and side walls by supplying a fluid molten resin composition containing a thermoplastic resin to the pair of molds, wherein the press-molded body has a ratio of the length of the bottom to the length of the side walls of 1.0 to 5.0, the pair of molds comprises a first space portion for forming the bottom of the press-molded body, a second space portion for forming the side walls of the press-molded body, and a third space portion for forming burrs at the end of the side walls, the molten resin composition is supplied to the first space portion, the flow path of the molten resin composition in the third space portion has a first flow path extending parallel to the compression direction of the pair of molds, the width of the first flow path is 0.03 mm to 0.1 mm, the length of the first flow path is 1.0 mm or more, and the length of the side walls is one-third or less. <5> <4> A press-molded body manufacturing apparatus equipped with a mold device. [Examples]

[0101] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0102] [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 supplied to a core mold that had been preheated to 150°C by injecting the resin. Next, the core mold containing the P3HB3HH resin was closed with a cavity mold, also heated to 150°C, thereby supplying molten resin between the pair of molds. The pair of molds supplied with 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 a pressing time of 20 seconds. The pair of molds, after the hot pressing was completed, were immediately sandwiched between upper and lower cooling plates heated to 25°C, and press forming was performed by cooling press at a press pressure of 30KN for a pressing time of 300 seconds. After press forming, the molds were opened and a rotationally symmetrical bottomed cylindrical press-formed body was removed. The resulting press-formed body had a bottom length of 60 mm and a side wall length of 60 mm.

[0103] (Mold) The molds used were similar to the pair of molds 30A shown in 601 of Figure 6. Here, aluminum alloy (A7075) was used as the mold material for the cavity mold 31A and the core mold 32A, respectively. Unlike the configuration shown in 601 of Figure 6, the core mold 32A has a recess formed on the surface that forms the inner bottom surface of the press-formed body, and the cavity mold 31A has a protrusion formed on the surface that forms the outer bottom surface of the press-formed body that is sized to fit into the recess.

[0104] Furthermore, the width of the first channel in the mold was set to 0.03 mm, and the length of the first channel was set to 3 mm. The length of the first channel corresponds to 1 / 20th of the length of the side wall portion of the obtained press-molded body.

[0105] [Comparative Example 1] The press-formed body was manufactured in the same manner as in Example 1, except that a mold similar to the pair of molds 30' shown in Figure 5 was used. In this comparative example, as in Example 1, the mold used had a recess formed on the surface that forms the inner bottom surface of the press-formed body in the core mold 32', and a protrusion formed on the surface that forms the outer bottom surface of the press-formed body in the cavity mold 31' that is sized to fit into the recess.

[0106] (Evaluation method) <Bubble generation evaluation> The side surfaces of the press-molded products in Example 1 and Comparative Example 1 were visually inspected to determine whether or not air bubbles were present on the side walls, and evaluated as follows. Good: No air bubbles. Unacceptable: Contains air bubbles.

[0107] The evaluation results are shown in Table 1.

[0108] [Table 1]

[0109] Regarding the evaluation results for bubble formation, as is clear from the results shown in Table 1, the press-molded article of Comparative Example 1 had multiple bubbles on its side surface. On the other hand, the press-molded article of Example 1 showed no bubbles and had a good appearance.

[0110] [Example 2] To analyze the internal pressure in the molded portion of the press-formed body during press molding by supplying molten resin between a pair of molds similar to those shown in Figure 6, the analysis was performed using Moldflow Insight Ultimate 2025 (AUTO DESK), a resin flow analysis software. The resin used in the analysis was PP (Generic PP), with a melt flow rate of 14 [g / 10 min, 230°C] and a viscosity of 263 Pa-s. The molding conditions were: mold surface temperature of 160°C, resin temperature of 220°C, press compression time of 30 seconds, upper limit of press speed of 20 mm / s, upper limit of press compression force of 20 t, and press force control switching when the upper limit of compression force was reached. The mold material was aluminum A7075, with a specific heat of 900 J / kg·C and a thermal conductivity of 130 W / m·C. Unlike the structure shown at 601 in Figure 6, the core mold 32A has a recess formed on the surface that forms the inner bottom surface of the press-formed body, and the cavity mold 31A has a protrusion formed on the surface that forms the outer bottom surface of the press-formed body that is sized to fit into the recess. For the mesh information, the 3D analysis had approximately 700,000 elements, an edge length of 0.9 mm, and 10 layers. The product volume was 12.8 cm³. 3 The measured value is 13.2 cm 3 The width of the first channel of the mold was 0.03 mm, and the length of the first channel was 3 mm. The internal pressure of the mold was calculated at the time it took for the material to pass through the first channel. The length of the first channel corresponds to 1 / 40th of the length of the side wall of the resulting press-formed body.

[0111] [Example 3] The analysis was performed under the same analytical conditions as in Example 2, except that the width of the first flow channel in the mold was set to 0.05 mm.

[0112] [Example 4] The analysis was performed under the same analytical conditions as in Example 2, except that the width of the first flow channel in the mold was set to 0.1 mm.

[0113] [Example 5] The analysis was performed under the same analytical conditions as in Example 2, except that the length of the first flow path in the mold was set to 1 mm.

[0114] [Example 6] Product volume 12.9 cm 3 The analysis was performed under the same analytical conditions as in Example 2, except that the length of the first flow channel in the mold was set to 5 mm. In Example 6, the length of the first flow channel corresponds to 1 / 24th of the length of the side wall portion of the obtained press-molded body.

[0115] [Example 7] The product volume is 12.9 cm³. 3 The analysis was performed under the same analytical conditions as in Example 2, except that the length of the first flow channel in the mold was set to 8 mm. In Example 7, the length of the first flow channel corresponds to 1 / 15th of the length of the side wall portion of the obtained press-molded body.

[0116] [Comparative Example 2] The analysis was performed under the same analytical conditions as in Example 2, except that the width of the first flow path in the mold was set to 0.15 mm.

[0117] [Comparative Example 3] The analysis was performed under the same analytical conditions as in Example 2, except that the first flow path was absent. The molds of this comparative example are similar to the pair of molds 30' shown in Figure 5. The core mold 32A has a recess formed on the surface that forms the inner bottom surface of the press-formed body, and the cavity mold 31A has a protrusion formed on the surface that forms the outer bottom surface of the press-formed body that is sized to fit into the recess.

[0118] The analysis results are shown in Table 2.

[0119] [Table 2]

[0120] Compared to the case without the first channel, the internal pressure increased when the first channel was present. Furthermore, the smaller the width of the first channel, the greater the internal pressure. The longer the length of the first channel, the greater the internal pressure. In Examples 2-7 and Comparative Examples 2 and 3, it is considered that if the internal pressure in the part forming the side wall of the press-molded body is 10 MPa or higher, the generation of air bubbles in the molded body can be suppressed.

[0121] In the methods using the pair of molds in Comparative Examples 2 and 3, the internal pressure in the part that forms the side wall of the press-formed body does not rise sufficiently, and it is thought that air bubbles are likely to form in the resulting molded body.

[0122] In contrast, the method using the pair of molds described in Examples 2 to 7 is thought to be able to sufficiently increase the internal pressure in the part that forms the side wall of the press-molded body, thereby suppressing the generation of air bubbles in the resulting molded body. [Industrial applicability]

[0123] 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]

[0124] 1. Molten resin generation section 2 Supply section 2a Discharge part 10. Manufacturing equipment (machinery for manufacturing press-formed products) 30, 30', 30A, 30B, 30C molds (a pair of molds) 31, 31', 31A, 31B, 31C Cavity type 32, 32', 32A, 32B, 32C core types A Press-formed body A1 bottom A2 opening A3 side wall A4, A4a, A4b, A4c Bali R1 Bottom molding channel (channel for molten resin composition in the first spatial portion) R2 Sidewall molding channel (channel for molten resin composition in the second spatial portion) R3 Deburring channel (channel for molten resin composition in the third spatial portion) R31 First channel R32 Second channel S1 1st spatial part S2 2nd spatial part S3 3rd space part

Claims

1. A method for manufacturing a press-molded body having a bottom and side walls, 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, The aforementioned press-formed body has a ratio of 1.0 to 5.0 between the length of the bottom and the length of the side wall. The pair of molds are A first space portion for forming the bottom of the press-formed body, A second space portion for forming the side wall portion of the press-formed body, The end portion of the side wall portion comprises a third space portion for forming a burr, The flow path of the molten resin composition in the third spatial portion has a first flow path that extends in a direction parallel to the compression direction of the pair of molds. A resin supply step of supplying the molten resin composition to the first spatial portion of the pair of molds, The process includes closing the pair of molds and filling the molten resin composition from the first space portion to the third space portion and press molding, The width of the first channel is 0.03 mm to 0.1 mm. A method for manufacturing a press-formed article, wherein the length of the first channel is 1.0 mm or more and is one-third or less of the length of the side wall portion.

2. The method for manufacturing a press-molded article according to claim 1, wherein the flow path of the molten resin composition in the third spatial portion comprises the first flow path and the second flow path extending in a direction different from the compression direction of the pair of molds.

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

4. 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 press-molded body having a bottom and side walls, The aforementioned press-formed body has a ratio of 1.0 to 5.0 between the length of the bottom and the length of the side wall. The pair of molds are A first space portion for forming the bottom of the press-formed body, A second space portion for forming the side wall portion of the press-formed body, It comprises a third space portion for forming burrs at the end of the side wall portion, The molten resin composition is supplied to the first space portion. The flow path of the molten resin composition in the third spatial portion has a first flow path that extends parallel to the compression direction of the pair of molds, The width of the first channel is 0.03 mm to 0.1 mm. A mold apparatus in which the length of the first channel is 1.0 mm or more and is one-third or less of the length of the side wall portion.

5. A press-formed article manufacturing apparatus comprising the mold apparatus described in claim 4.

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