Method and apparatus for manufacturing press-molded body

Abstract

To realize a method for manufacturing a press-molded body of P3HA resin that has an excellent mold-releasing property and reduces a press-molding temperature or press-molding pressure when manufacturing the press-molded body.SOLUTION: The method for manufacturing the press-molded body uses a pair of molds (31) with forming surfaces (32A, 33A) that have surface free energy of 26.0 mN / m or less.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a method and an apparatus for producing a press-molded article of a poly(3-hydroxyalkanoate) resin (hereinafter sometimes referred to as "P3HA resin"). [Background technology]

[0002] In recent years, there has been hope for the use of biodegradable plastics to combat marine pollution caused by plastics. However, a report compiled by the United Nations Environment Programme in 2015 pointed out that compostable plastics such as polylactic acid cannot be expected to decompose in a short period of time in the cold ocean, and therefore cannot be used as a measure against marine pollution.

[0003] In this context, P3HA-based resins are attracting attention as a material that can solve the above problems because they are capable of biodegrading even in seawater.

[0004] For example, Patent Document 1 discloses a technique in which a resin composition containing a poly(3-hydroxyalkanoate) resin is molded into a sheet using a molding machine, and the sheet-like molded product is press-molded.

[0005] Also known is a technique in which a thermoplastic biodegradable resin is heated to form a molten resin, the molten resin is fed between dies, the dies are closed to perform press molding, and then the resin is cooled to obtain a molded product. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2006-077063 A Summary of the Invention [Problem to be solved by the invention]

[0007] Here, it has been found that when a resin composition containing a poly(3-hydroxyalkanoate)-based resin is heated to form a molten resin, the molten resin is supplied between dies, and the dies are closed to perform press molding, the following problems arise.

[0008] (i) A press-molded product obtained using a metal or metal alloy die is stuck to the die with a very strong force, making it difficult to remove from the die (poor demolding properties). Therefore, there is a risk that the press-molded product will deform when released from the die.

[0009] (ii) In order to reduce manufacturing costs, there has been a demand for technology that can reduce the press molding pressure and the heating temperature of a pair of dies during press molding (sometimes simply referred to as the press molding temperature), as well as shorten the molding time.

[0010] One aspect of the present invention aims to provide a method and apparatus for producing a press-molded body of a P3HA-based resin, which has excellent releasability and can reduce the press molding temperature or press molding pressure when producing the press-molded body. [Means for solving the problem]

[0011] In order to solve the above problems, a manufacturing method for a press-molded product according to one embodiment of the present invention includes a heating step of heating a resin composition containing a poly(3-hydroxyalkanoate)-based resin to form a molten resin composition, a resin supplying step of supplying the molten resin composition between a pair of dies by discharging it from a discharge portion, and a molding step of closing the pair of dies and press-molding the flowable molten resin composition and cooling it, wherein the surface free energy of the molding surfaces of the pair of dies is 26.0 mN / m or less.

[0012] In addition, in order to solve the above-mentioned problems, a press-molded body manufacturing apparatus according to one embodiment of the present invention is a press-molded body manufacturing apparatus equipped with a pair of molds for filling a molten resin composition containing a poly(3-hydroxyalkanoate)-based resin, and is equipped with a molten resin generation section for heating the poly(3-hydroxyalkanoate)-based resin composition to generate a molten resin composition, a supply section having a discharge section for discharging the molten resin composition and supplying the molten resin composition between the pair of molds by the discharge section, and a molding section for closing the pair of molds to press-mold and cool the flowable molten resin composition, and the surface free energy of the molding surfaces of the pair of molds is 26.0 mN / m or less. Effect of the Invention

[0013] According to one aspect of the present invention, when a press-molded article of a P3HA resin is produced, the mold releasability is excellent and the press molding temperature or press molding pressure can be reduced. [Brief description of the drawings]

[0014] [Figure 1] 1 is a diagram showing a schematic configuration of a manufacturing apparatus for a press-molded body according to an embodiment of the present invention; [Diagram 2] 1 is a diagram showing a schematic configuration of a molding section of a manufacturing apparatus for a press-molded body according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] An embodiment of the present invention will be described in detail below. In this specification, unless otherwise specified, "A to B" representing a numerical range means "A or more, B or less." In addition, all documents described in this specification are incorporated herein by reference.

[0016] [Technical philosophy] When press-molding a P3HA resin as a biodegradable resin, the present inventors adopted Method B, in which a molten resin obtained by heating a P3HA resin is press-molded in a mold while still in a molten state that allows it to flow, rather than Method A, in which a sheet-like material made of a P3HA resin is press-molded in a mold. Note that Method A corresponds to the method disclosed in Patent Document 1.

[0017] In the production of a press-molded body by the above-mentioned method B, since the P3HA-based resin composition in a molten state is flowable in a mold, if the press molding pressure is low or the temperature of the mold during press molding is low, the mold does not close completely during press molding with a short mold heat press time, and the film thickness of the press-molded body becomes larger than the designed film thickness. Therefore, when producing a press-molded body of a P3HA-based resin, in order to shorten the mold heat press time and shorten the molding time (molding tact time), it is necessary to increase the press molding temperature or press molding pressure, which results in an increase in equipment costs. In addition, in order to produce a press-molded body of a designed film thickness while lowering the press molding pressure or press molding temperature, it is necessary to increase the mold heat press time and molding time. Thus, it has been difficult to reduce the press molding pressure and press molding temperature in order to reduce production costs (reducing equipment costs).

[0018] In addition, press-molded bodies made using a metal mold are adhered to the mold with extremely strong force, making them difficult to remove from the mold (poor demolding properties). As a result, there was a problem that the press-molded body would deform when released from the mold.

[0019] Therefore, the inventors conducted extensive research to solve the above problems and discovered that by surface-treating the molding surface of a mold and adjusting the surface free energy of the molding surface to a certain range, it is possible to achieve excellent release properties and reduce the press molding temperature or press molding pressure when producing a press-molded body of a P3HA-based resin.

[0020] A manufacturing method for a press-molded body according to one embodiment of the present invention (hereinafter, sometimes referred to as this manufacturing method) was obtained based on the above findings, and comprises a heating step of heating a resin composition containing a poly(3-hydroxyalkanoate)-based resin to form a molten resin composition, a resin supplying step of supplying the molten resin composition between a pair of dies by discharging it from a discharge portion, and a molding step of closing the pair of dies and press-molding the flowable molten resin composition and cooling it, wherein the surface free energy of the molding surfaces of the pair of dies is 26.0 mN / m or less.

[0021] According to this manufacturing method, the surface free energy of the molding surfaces of the pair of molds is 26.0 mN / m or less, so that when producing a press-molded body of a P3HA-based resin, excellent mold releasability is achieved and the press molding temperature or press molding pressure can be reduced.

[0022] Furthermore, this manufacturing method can suppress marine pollution caused by waste, which can contribute to the achievement of the Sustainable Development Goals (SDGs), such as Goal 12 "Ensure sustainable consumption and production patterns" and Goal 14 "Conserve and sustainably use the oceans and marine resources for sustainable development." The manufacturing method is described in detail below.

[0023] [Method for producing press-molded body] As described above, the present manufacturing method includes the heating step, the resin supplying step, and the press molding step, and produces a press-molded body of a P3HA resin through the heating step, the resin supplying step, and the press molding step.

[0024] In the heating step, the resin composition containing the P3HA resin is heated to form a molten resin composition. The method for heating the resin composition can be any conventionally known method as long as it can form a molten resin composition containing the P3HA resin. Preferably, the heating step includes a melt-kneading step of melt-kneading the resin composition containing the P3HA resin.

[0025] The mode of the melt-kneading step is not particularly limited as long as a melt-kneaded resin composition can be obtained. Specific examples of the melt-kneading step include the following methods (a1) and (a2): (a1) A method in which a resin composition containing a P3HA resin is prepared by mixing or blending using a mixer or the like, and then the resin composition is supplied to a melt kneading device and melt kneaded; (a2) A method in which raw materials for a resin composition containing a P3HA-based resin are supplied to a melt kneading apparatus, and a resin composition is prepared (completed) in the melt kneading apparatus, and the resin composition is melt kneaded.

[0026] In the method (a1), the order in which the raw materials for the resin composition containing the P3HA resin are mixed or blended (dry blended) is not particularly limited. In the method (a2), the order in which the raw materials for the resin composition containing the P3HA resin are fed to the melt kneader is not particularly limited.

[0027] In the method (a1), the mixing device is not particularly limited, and examples thereof include a ribbon blender, a flash blender, a tumbler mixer, and a super mixer.

[0028] In the above methods (a1) and (a2), the melt kneading device is not particularly limited, and examples thereof include an extruder, a kneader, a Banbury mixer, and a roll, etc. From the viewpoint of excellent productivity and convenience, the melt kneading device is preferably an extruder, and more preferably a twin-screw extruder.

[0029] In the melt-kneading step, the temperature at which the resin composition is melt-kneaded cannot be generally specified because it depends on the physical properties of P3HA (melting point, weight average molecular weight, etc.) and the type of additive used. Regarding the temperature at which the resin composition is melt-kneaded, for example, the temperature of the melt-kneaded resin composition discharged from the discharge part (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 P3HA resin may be generated. On the other hand, if the composition temperature is 180°C or higher, the P3HA resin may be thermally decomposed.

[0030] In the resin supplying step, the molten resin composition is discharged from a discharge portion to be supplied between a pair of dies. In the resin supplying step, the molten resin composition is discharged from a discharge portion while in a molten state to a pair of dies. Thus, the molten resin composition in a molten state is supplied between a pair of dies.

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

[0032] In addition, in the resin supplying step, the configuration of the discharge section is not particularly limited as long as it is capable of discharging the molten resin composition, and a conventionally known configuration can be adopted. From the viewpoint of improving the productivity of the press molded body, it is preferable that the discharge section is configured to be capable of quantitatively discharging the molten resin composition. Examples of the configuration of such a discharge section include a configuration equipped with a gear pump and a configuration equipped with an automatic opening and closing nozzle. Specific examples of the discharge section include a plunger type discharger, a pre-plunger type discharger, and a screw type discharger.

[0033] In the press molding step, the pair of dies are closed to press-molde and cool the flowable molten resin composition. In the resin supply step, the molten resin composition is supplied between the pair of dies in a molten state, so that the molten resin composition can flow in the space between the pair of dies even if the pair of dies are closed in the press molding step.

[0034] In the resin supplying step, the molten resin composition in a molten state is supplied between a pair of dies, and then in the press molding step, the pair of dies are subjected to a heat press using a heat press molding machine. Then, the pair of dies after the heat press is completed are cooled to perform press molding. After the press molding, the pair of dies are opened to obtain a press molded body.

[0035] The heat press molding machine used in the resin supplying step is not particularly limited as long as it is configured to be capable of heat pressing a pair of dies to which the molten resin composition is supplied. A conventionally known device can be used as the heat press molding machine.

[0036] The method for cooling the pair of dies after the hot pressing is not particularly limited. For example, a method of sandwiching the pair of dies after the hot pressing between a pair of cooling plates and performing cold pressing can be mentioned.

[0037] In this method, the pressing pressure during cold pressing is not particularly limited, but is preferably 10 KN to 100 KN, and more preferably 30 KN to 50 KN. By setting the pressing pressure within the above numerical range, there is an advantage that a press-molded body having a uniform thickness can be obtained.

[0038] The pressing time during the cold pressing is not particularly limited, but is preferably 60 to 600 seconds, and more preferably 120 to 300 seconds. Setting the pressing time within the above range has the advantage that the solidification of the P3HA resin proceeds sufficiently, making it easy to remove the press-molded body.

[0039] The temperature of the cooling plate used in the cooling press is not particularly limited, but is preferably 10° C. to 60° C., and more preferably 20° C. to 50° C. Setting the temperature of the cooling plate within the above range has the advantage that the solidification of the P3HA resin proceeds sufficiently, making it easy to remove the press-molded body.

[0040] This manufacturing method employs a method B in which a molten resin composition containing a P3HA resin is press-molded in a pair of dies while in a flowable molten state. In the method B, the pair of dies is preheated to make the molten resin composition supplied between the pair of dies flowable. If the heating temperature (press molding temperature) of the pair of dies during press molding is lowered, the heat press time of the dies tends to be longer, making it difficult to shorten the molding time (molding tact time). Similarly, if the press molding pressure of the pair of dies by the heat press molding machine is lowered, the heat press time of the dies tends to be longer, making it difficult to shorten the molding time. In order to shorten the molding time, it is necessary to increase the press molding temperature and press molding pressure, which increases manufacturing costs such as equipment costs. In other words, it is difficult to reduce the press molding pressure and press molding temperature in order to reduce manufacturing costs.

[0041] Here, in the present manufacturing method, the surface free energy of the molding surfaces of the pair of molds is 26.0 mN / m or less. The surface free energy of the molding surfaces is preferably 22 mN / m or less, and more preferably 18 mN / m or less. Furthermore, regarding the lower limit of the surface free energy of the molding surfaces, the surface free energy is preferably 10 mN / m or more, and more preferably 14 mN / m or more. Here, the "molding surface" refers to the surface of the pair of molds that comes into contact with the molten resin composition, and can also be said to be the opposing surfaces of the pair of molds that face each other.

[0042] According to this manufacturing method, since the surface free energy is within the above-mentioned numerical range, when a press-molded body of a P3HA-based resin is manufactured, the mold releasability is excellent and the press molding temperature or the press molding pressure can be reduced. Furthermore, according to this manufacturing method, even if the press molding pressure is low or the mold temperature during press molding is low, the mold closes during press molding in a short mold heat press time, and the film thickness of the press-molded body can be the designed film thickness. Therefore, according to this manufacturing method, the molding time can be shortened.

[0043] The surface free energy can be calculated as follows. First, pure water and diiodomethane (CH2I2) are dropped onto the molding surface using a contact angle meter, and the contact angle θ between each droplet and the mold surface is measured. From the measured contact angle θ, the surface free energy of the molding surface is calculated by the Owens-Wendt method.

[0044] The heating temperature of the pair of dies during press molding (press molding temperature) may be any temperature at which the composition temperature of the molten resin composition can be maintained, and is preferably equal to or lower than the composition temperature of the molten resin composition, and more preferably from the composition temperature of the molten resin composition minus 100° C. to the composition temperature of the molten resin composition. According to the present production method, even at a relatively low press molding temperature within the above range, the molding time can be shortened.

[0045] In addition, the press molding pressure of the pair of dies by the heat press molding machine is not particularly limited, but is preferably 10 KN to 300 KN, and more preferably 40 KN to 200 KN. According to the present manufacturing method, even if the press molding pressure is relatively low within the above numerical range, the molding time can be shortened.

[0046] The heat press time of the pair of dies by the heat press molding machine is not particularly limited, but is preferably 1 to 60 seconds, and more preferably 3 to 20 seconds. According to the present manufacturing method, even if the heat press time is set relatively short as in the above numerical range, the molding time can be shortened.

[0047] Moreover, the above molding surface exists in each of the pair of molds. In this manufacturing method, the molding surface exhibiting the surface free energy within the above range may be the molding surface of at least one of the pair of molds, and is preferably the molding surface of both of the pair of molds. The molding surface exhibiting the surface free energy within the above range may be the molding surface of a concave mold (cavity). Moreover, it is more preferable that the region exhibiting the surface free energy within the above range is the entire molding surface.

[0048] Furthermore, the press-molded body suitable for this manufacturing method is not particularly limited, but is a molded body having a rising portion (e.g., a side wall portion of the press-molded body) having a thickness of 0.1 mm to 0.4 mm, preferably 0.2 mm to 0.3 mm, rising in the pressing direction.

[0049] The molding surfaces of the pair of dies may be subjected to any surface treatment so long as the surface free energy is 26.0 mN / m or less. In this manufacturing method, the molding surfaces of the pair of dies are preferably subjected to a plating treatment for forming a metal coating in which a fluororesin is dispersed. That is, the molding surfaces of the pair of dies are preferably subjected to a composite plating treatment of a fluororesin and a metal. The fluororesin is preferably in the form of particles.

[0050] By subjecting the molding surfaces of the pair of dies to the plating treatment, the slipperiness of the molten resin composition on the molding surfaces is improved. Therefore, even if the press molding temperature or press molding pressure is reduced, the fluidity of the molten resin composition is improved. As a result, when producing a press molded product of a P3HA resin, the mold releasability is excellent and the press molding temperature or press molding pressure can be reduced.

[0051] The content of the fluororesin in the metal coating is not particularly limited as long as the above-mentioned effects are achieved, but it is preferably 1 vol % to 50 vol %, and more preferably 5 vol % to 30 vol %.

[0052] Furthermore, the thickness of the metal coating is not particularly limited as long as it provides the above-mentioned effects, but is preferably 1 μm to 50 μm, and more preferably 3 μm to 20 μm.

[0053] The fluorine-based resin is not particularly limited, but examples thereof include perfluoroalkoxyalkane (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), polytetrafluoroethylene (PTFE), and the like.

[0054] The coating formed by the above surface treatment may be a composite film of a metal coating and a fluororesin coating. The metal constituting the metal coating is not particularly limited, but is preferably one or more selected from the group consisting of nickel-based metals, chromium-based metals, iron-based metals, and alumina-based metals.

[0055] In this manufacturing method, a preferred embodiment of the plating treatment is so-called nickel Teflon (registered trademark) plating treatment (nickel-PTFE composite plating) in which PTFE particles are uniformly dispersed in a nickel plating film.

[0056] In the present manufacturing method, the arithmetic mean roughness Ra and the arithmetic mean roughness Ra of the molding surfaces of the pair of dies may be set so that the surface free energy is 26.0 mN / m or less. The molding surfaces of the pair of dies preferably have an arithmetic mean roughness Ra in the range of 0.1 μm to 1.0 μm and a maximum height Rz in the range of 0.5 μm to 10.0 μm. The arithmetic mean roughness Ra of the molding surfaces of the dies is more preferably 0.2 μm to 0.9 μm, and particularly preferably 0.3 μm to 0.8 μm. The maximum height Rz of the molding surfaces of the dies is more preferably 1.0 μm to 8.0 μm, and particularly preferably 2.0 μm to 6.0 μm. The arithmetic mean roughness Ra and the maximum height Rz can be measured according to a conventionally known method, for example, JIS B 0601-2001.

[0057] By setting the arithmetic mean roughness Ra and maximum height Rz of the molding surface of the above-mentioned mold within the above-mentioned range, the above-mentioned molding surface becomes an uneven surface having a function of reducing the resistance caused by the flowable molten resin composition, and has a liquid repellent function (for example, a lotus leaf effect). As a result, the flowability of the molten resin composition in the pair of molds is improved, and the press-molded body has excellent releasability.

[0058] Furthermore, by subjecting the molding surface to a roughening treatment, it is possible to form a molding surface that exhibits an arithmetic mean roughness Ra and a maximum height Rz within the above ranges. The roughening treatment can be performed by a conventionally known method, but is preferably at least one surface treatment selected from shot peening and blasting.

[0059] The shot peening process is a surface treatment in which spherical particles are projected against the molding surfaces of a pair of dies by air pressure and collided with them to form irregularities on the molding surfaces. The shot peening process smooths the surface roughness of the molding surfaces and imparts compressive residual stress. In the shot peening process, various conditions such as the material and diameter of the spherical particles, the projection angle and projection speed of the spherical particles (i.e., air pressure), and the processing time are not particularly limited as long as they are set so that the molding surfaces exhibit an arithmetic mean roughness Ra within the above range and a maximum height Rz within the above range, and can be appropriately set according to the set values ​​of the arithmetic mean roughness Ra and the maximum height Rz within the range.

[0060] The blasting process is a surface treatment in which polygonal particles are projected against the molding surfaces of a pair of dies by air pressure and collided to form irregularities on the molding surfaces. In this manufacturing method, the blasting process is similar to the shot peening process in that it forms irregularities on the molding surfaces, but differs from the shot peening process in that it does not impart compressive residual stress to the molding surfaces. In the blasting process, various conditions such as the material and diameter of the polygonal particles, the projection angle and projection speed of the spherical particles (i.e., air pressure), and the processing time are not particularly limited as long as they are set so that the molding surfaces exhibit an arithmetic mean roughness Ra within the above range and a maximum height Rz within the above range, and can be appropriately set according to the set values ​​of the arithmetic mean roughness Ra and the maximum height Rz within the range.

[0061] In the present manufacturing method, it is preferable that the molding surfaces of the pair of dies are subjected to a silicon surface coating treatment. The silicon surface coating treatment improves the slipperiness of the molten resin composition on the molding surfaces. Therefore, even if the press molding temperature or press molding pressure is reduced, the fluidity of the molten resin composition is improved. As a result, when a press molded body of a P3HA resin is manufactured, it is possible to reduce the press molding temperature or press molding pressure while having excellent mold releasability.

[0062] The silicon surface coating treatment is not particularly limited, but examples thereof include silicone resin coating treatment and organopolysilazane coating treatment.

[0063] Resins used in the silicone resin coating treatment include, for example, organopolysiloxanes. Examples of the organopolysiloxanes include dimethylpolysiloxanes. The organopolysiloxanes are preferably used in silicon surface coating treatments because they become a glass film through a dealcoholization reaction and form a hard surface.

[0064] The polysilazane used in the organopolysilazane coating treatment is, for example, dimethylpolysilazane, etc. The polysilazane is preferably used for silicon surface coating treatment because it becomes a glass film by deammonia reaction and forms a hard surface.

[0065] Furthermore, the thickness of the film formed by the silicon surface coating treatment is not particularly limited as long as it provides the above-mentioned effects, but it is preferably 0.5 μm to 15 μm, and more preferably 1 μm to 5 μm.

[0066] In the present manufacturing method, the molding surface of the mold is preferably subjected to both (a) a roughening treatment (hereinafter sometimes simply referred to as a roughening treatment) to provide an arithmetic mean roughness Ra and a maximum height Rz within the above range so that the surface free energy of the molding surface is within the above numerical range, and (b) a plating treatment (hereinafter sometimes referred to as a fluorine-metal composite plating treatment) to form a metal coating in which a fluororesin is dispersed. The molding surface of the mold may be (1) a surface that has been subjected to a fluorine-metal composite plating treatment before the roughening treatment, or (2) a surface that has been subjected to a fluorine-metal composite plating treatment after the roughening treatment. In the case of (1), the roughening treatment may cause partial peeling of the metal coating formed by the fluorine-metal composite plating treatment, and in the case of (2), the roughening treatment before the fluorine-metal composite plating treatment improves the adhesion of the metal coating formed by the fluorine-metal composite plating treatment, so (2) is more preferable.

[0067] In addition, it is preferable that the molding surface of the mold is subjected to both (a) a roughening treatment and (c) a silicon surface coating treatment so that the surface free energy of the molding surface falls within the above-mentioned numerical range.

[0068] [Press-molded body manufacturing device] An apparatus for manufacturing a press-molded body according to one embodiment of the present invention (hereinafter, sometimes referred to as the present manufacturing apparatus) is configured to realize the present manufacturing method. Fig. 1 is a diagram showing a schematic configuration of the present manufacturing apparatus. Fig. 2 is a diagram showing a schematic configuration of a molding section of the present manufacturing apparatus.

[0069] As shown in Fig. 1, a press-molded body manufacturing apparatus 10 according to one embodiment of the present invention includes a pair of dies for filling a molten resin composition containing a P3HA resin. Of the pair of dies, the lower die is shown in Fig. 1. The manufacturing apparatus 10 includes a molten resin generating section 1 and a supplying section 2.

[0070] The molten resin production section 1 heats the P3HA resin composition to produce a molten resin composition. The molten resin production section 1 includes a raw material input section for inputting raw materials for the P3HA resin composition. The molten resin production section 1 includes a melt kneading device that melts and kneads the raw materials input from the raw material input section. The molten resin production section 1 may also include a mixing device that mixes the raw materials, as necessary. Examples of the melt kneading device and the mixing device include the above-mentioned devices.

[0071] The supply section 2 has a discharge section 2a that discharges the molten resin composition generated in the molten resin generation section 1. The discharge section 2a can have the configuration of the discharge section described above. The supply section 2 supplies the molten resin composition to between the pair of molds by the discharge section 2a. In the configuration shown in FIG. 1, the supply section 2 is configured to discharge the molten resin composition from the discharge section 2a to the lower mold. After a predetermined amount of the molten resin composition is supplied to the lower mold, the upper mold is placed on the lower mold, and the molten resin composition is supplied between the pair of molds.

[0072] As shown in FIG. 2, the manufacturing apparatus 10 includes a molding section 30. The molding section 30 closes a pair of dies 31 to press-mold and cool the flowable molten resin composition. The molding section 30 includes a heat press molding machine that performs heat pressing on the pair of dies 31, and a cooling device that cools the pair of dies 31 after the heat pressing is completed. The heat 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 sandwich the pair of dies 31, and the pair of dies 31 may be cold-pressed by the cooling plates.

[0073] 2 is a die for forming a press-molded body having a concave shape with a recess. The pair of dies 31 includes a lower die 32 and an upper die 33.

[0074] In the manufacturing apparatus 10, the surface free energy of the molding surfaces 32A and / or 33A of the pair of molds 31 is 26.0 mN / m or less. When the surface free energy of the molding surfaces of the mold 31 is within the above numerical range, excellent releasability is achieved and the press molding temperature or press molding pressure can be reduced when a press molded article of a P3HA resin is manufactured.

[0075] Here, molding surfaces 32A and 33A can be said to be surfaces that form a molding space formed by lower mold 32 and upper mold 33.

[0076] In the present manufacturing apparatus, it is preferable that a surface treatment with a fluororesin is applied to molding surfaces 32A and / or 33A of the pair of molds 31. The surface treatment with a fluororesin may be applied to at least one of the molding surfaces of the molds, molding surface 32A of lower mold 32 and molding surface 33A of upper mold 33, and is preferably applied to both lower mold 32 and upper mold 33.

[0077] Furthermore, the molding surface of lower die 32 has rising surfaces 32b and 32c, and the molding surface of upper die 33 has rising surfaces 33b and 33c. Rising surfaces 32b and 33b and rising surfaces 32c and 33c are molding surfaces that respectively constitute the thin-walled portions of the rising parts that rise in the pressing direction in the press-molded body. In molding surfaces 32A and 33A of a pair of dies 31, the region exhibiting surface free energy within the above range is preferably the entire region of molding surface 32A and / or 33A.

[0078] In addition, the distance between rising surface 32b and rising surface 33b and the distance between rising surface 32c and rising surface 33c define the thickness of the thin portion of the rising portion of the press-molded body in the pair of dies 31. In the pair of dies 31, the distance between these rising surfaces is specified so that the thickness of the rising portion of the press-molded body is 0.1 mm to 0.4 mm, preferably 0.2 mm to 0.3 mm.

[0079] (P3HA resin) The resin composition used in the present production method includes a P3HA-based resin. In this specification, the term "P3HA-based 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 where n is an integer of 1 or more and 15 or less.) is a polyhydroxyalkanoate containing this as a repeating unit.

[0080] More specifically, the P3HA resin preferably contains 3-hydroxybutyrate (3HB) units. The P3HA resin containing 3HB units is, for example, one or more selected from the group consisting of 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).

[0081] The P3HA resin may contain only one type, or may contain two or more types.

[0082] The P3HA resin is preferably a P3HA resin produced by a microorganism (a microbially produced P3HA resin). A microbially produced P3HA resin is usually composed only of D-form (R-form) polyhydroxyalkanoate monomer units. Among the microbially produced P3HA resins, P3HB, P3HB3HH, P3HB3HV, P3HB3HV3HH, and P3HB4HB are preferred, and P3HB, P3HB3HH, P3HB3HV, and P3HB4HB are more preferred, in terms of ease of industrial production.

[0083] Microorganisms that produce microbially produced P3HA resins are not particularly limited as long as they have the ability to produce P3HA resins. For example, the first P3HB-producing bacterium was Bacillus megaterium, discovered in 1925, and other natural microorganisms include Cupriavidus necator (formerly classified as Alcaligenes eutrophus and Ralstonia eutropha) and Alcaligenes latus. It is known that P3HB accumulates in the cells of these microorganisms.

[0084] Also, as bacteria that produce copolymers of hydroxybutyrate and other hydroxyalkanoates, Aeromonas caviae, which produces P3HB3HV and P3HB3HH, and Alcaligenes eutrophus, which produces P3HB4HB, are known. In particular, with regard to P3HB3HH, Alcaligenes eutrophus AC32 (FERM BP-6038) (T. Fukui, Y. Doi, J. Bateriol., 179, p4821-4830 (1997)) into which genes of P3HA resin synthesis enzyme group have been introduced is more preferable in order to increase the productivity of P3HB3HH, and microbial cells in which P3HB3HH has been accumulated in the 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 have been introduced may be used according to the P3HA resin to be produced, and culture conditions including the type of substrate may be optimized.

[0085] The P3HA resin also contains at least one copolymer of 3HB units and other hydroxyalkanoate units, and the 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate) resin account for 90.0 to 99.0 mol %, 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 all repeating units (100 mol %).

[0086] When the composition ratio of the 3HB repeating unit is 90.0 mol% or more, the rigidity of the P3HA resin is improved, the crystallization speed is accelerated, burrs are reduced, and productivity tends to be improved. On the other hand, when the composition ratio of the 3HB repeating unit is 99.0 mol% or less, the melting point is lower than the thermal decomposition temperature, so stable and continuous production is possible. The monomer composition ratio of the P3HA resin can be measured by gas chromatography or the like (see, for example, International Publication No. 2014 / 020838).

[0087] The molecular weight of the P3HA resin is not particularly limited as long as it shows substantially sufficient physical properties for the intended use. The weight average molecular weight of the P3HA resin is preferably in the range of 100,000 to 1,000,000, more preferably 150,000 to 700,000, further preferably 200,000 to 500,000, and particularly preferably 250,000 to 450,000. When the weight average molecular weight is 100,000 or more, appropriate mechanical strength is obtained. In addition, when the molecular weight is 1,000,000 or less, the increase in melt viscosity can be suppressed, and the moldability is excellent.

[0088] The weight average molecular weight can be measured by gel permeation chromatography (GPC) (Shodex GPC-101, manufactured by Showa Denko K.K.), using a polystyrene gel (Shodex K-804, manufactured by Showa Denko K.K.) as a column, and using chloroform as a mobile phase, and can be calculated as a molecular weight converted into polystyrene. In this case, a calibration curve is prepared using polystyrenes with weight average molecular weights of 31,400, 197,000, 668,000, and 1,920,000. As the column for the GPC, a column appropriate for measuring the molecular weight may be used.

[0089] The resin composition in the present manufacturing method may contain a second P3HA resin in addition to the P3HA resin. The second P3HA resin contains at least one copolymer of 3HB units and other hydroxyalkanoate units, and the 3HB units in the poly(3-hydroxyalkanoate) resin are 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 all repeating units (100 mol %). When the resin composition further contains the second P3HA resin, the toughness of the molded product is excellent.

[0090] The second P3HA resin is not particularly limited as long as it is different from the P3HA resin. Examples of the second P3HA resin include the resins exemplified as the P3HA resin.

[0091] 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, relative to 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 above-mentioned P3HA resin can be used as the second P3HA resin. In this specification, the term "total P3HA resin" refers to all P3HA resins contained in the resin composition in the present production method.

[0092] The resin composition may contain other resins other than the P3HA resin, as long as the effect of the present invention is 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 sebate terephthalate, and polybutylene azelate terephthalate. Only one type of other resin may be contained, or two or more types may be contained.

[0093] The content of the other resin is not particularly limited, but is preferably 50 parts by weight or less, more preferably 40 parts by weight or less, and even more preferably 30 parts by weight or less, relative to 100 parts by weight of the total P3HA resin. The lower limit of the content of the other resin is not particularly limited, and may be 0 parts by weight.

[0094] The resin composition does not need to contain an inorganic filler, but preferably further contains an inorganic filler. By containing an inorganic filler in the resin composition, the crystallization speed is improved, and effects such as reduction in burrs and improvement in the production cycle are achieved.

[0095] The inorganic filler is not particularly limited, but examples thereof 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, glass particles, etc. These may be used alone or in combination of two or more kinds.

[0096] The content of the inorganic filler 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, based on 100 parts by weight of the total P3HA resin. When the content of the inorganic filler is within the above range, a sufficient crystallization rate and toughness can be achieved at the same time.

[0097] The resin composition may contain additives that can be used together with the P3HA resin, as long as they do not impair the effects of the present invention. Examples of such additives include colorants such as pigments and dyes, odor absorbents such as activated carbon and zeolite, fragrances such as vanillin and dextrin, plasticizers, antioxidants, weather resistance improvers, ultraviolet absorbers, crystal nucleating agents, lubricants, release agents, water repellents, antibacterial agents, and sliding property improvers. Only one type of additive may be contained, or two or more types may be contained. The content of these additives can be appropriately set by those skilled in the art depending on the purpose of use.

[0098] The present invention is not limited to the above-described embodiments, 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.

[0099] That is, one embodiment of the present invention is as follows. <1> A method for producing a press-molded body, comprising: a heating step of heating a resin composition containing a poly(3-hydroxyalkanoate) resin to form a molten resin composition; a resin supplying step of supplying the molten resin composition between a pair of dies by discharging it from a discharge section; and a molding step of closing the pair of dies and press-molding the flowable molten resin composition, followed by cooling, wherein the surface free energy of the molding surfaces of the pair of dies is 26.0 mN / m or less. <2> The molding surfaces of the pair of dies are subjected to a plating process to form a metal coating having a fluororesin dispersed therein. <1> A method for manufacturing a press-molded body. <3> The molding surfaces of the pair of molds are subjected to a silicon surface coating treatment. <1> A method for manufacturing a press-molded body. <4> The molding surfaces of the pair of molds have an arithmetic mean roughness Ra in the range of 0.1 μm to 1.0 μm and a maximum height Rz in the range of 0.5 μm to 10.0 μm. <1> ~ <3> The manufacturing method of any one of the press-molded bodies. <5> The molding surfaces of the pair of dies are subjected to at least one surface treatment selected from a shot peening treatment and a blasting treatment. <4> A method for manufacturing a press-molded body. <6> The metal constituting the metal coating is at least one selected from the group consisting of nickel-based metals, chromium-based metals, iron-based metals, and alumina-based metals. <2> A method for manufacturing a press-molded body. <7> The press-molded body has a thickness of 0.1 mm to 0.4 mm at a rising portion rising in the pressing direction. <1> ~ <6> The method for producing any one of the press-molded bodies according to any one of the above. <8> The poly(3-hydroxyalkanoate)-based resin is at least one selected from the group consisting of poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), and poly(3-hydroxybutyrate-co-3-hydroxydecanoate). <1> ~ <7> The method for producing any one of the press-molded bodies according to any one of the above. <9> An apparatus for producing a press-molded product, comprising a pair of dies for filling a molten resin composition containing a poly(3-hydroxyalkanoate)-based resin, An apparatus for manufacturing press-molded products comprising: a molten resin generation section for heating a poly(3-hydroxyalkanoate)-based resin composition to generate a molten resin composition; a supply section having a discharge section for discharging the molten resin composition and supplying the molten resin composition between the pair of dies by the discharge section; and a molding section for closing the pair of dies and press-molding and cooling the flowable molten resin composition, wherein the surface free energy of the molding surfaces of the pair of dies is 26.0 mN / m or less. EXAMPLES

[0100] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0101] Example 1 The pair of dies shown in Figure 2 was used. The upper and lower dies in the pair were made of aluminum alloy (A7075). The entire molding surfaces of both the upper and lower dies were blasted and then treated with a 5μm thick nickel-PTFE composite plating (PTFE content 30vol%), which is a fluorine surface coating. In addition, the pair of dies used was designed so that the clearance between the molding surfaces of the upper and lower dies was 0.25mm, i.e., the design film thickness of the press molded body was 0.25mm.

[0102] For the molding surfaces of both the upper and lower dies described above, the arithmetic mean roughness Ra and the maximum height Rz were measured in multiple sections according to JIS B 0601-2001. As a result, the arithmetic mean roughness Ra was 0.40 μm and the maximum height Rz was 2.99 μm.

[0103] Furthermore, for both the molding surfaces of the upper and lower dies, pure water and diiodomethane (CH2I2) were dropped onto the die surfaces using a contact angle meter (PCA-11, manufactured by Kyowa Interface Science Co., Ltd.), and the contact angle θ between each droplet and the die surface was measured. From the contact angle θ, the surface free energy of the sample was calculated by the Owens-Wendt method.

[0104] Specifically, by substituting the contact angle θ of each droplet and the surface free energy γL of the liquid into the following equations (1) and (2) and solving the simultaneous equations, the surface free energy γ S In equations (1) and (2), γ is the surface free energy, L is the symbol for liquid, S is the symbol for solid, and d and h are the symbols for the dispersion component and hydrogen bond component of the surface free energy, respectively.

[0105] The calculated surface free energy was 25.0 mN / m.

[0106]

number

[0107] Example 2 A pair of dies similar to those used in Example 1 were used, except that the entire molding surfaces of both the upper and lower dies were subjected to a blast treatment, and the measured values ​​of the arithmetic average roughness Ra and maximum height Rz over multiple sections were 0.55 μm and 4.99 μm, respectively.

[0108] The surface free energy calculated in the same manner as in Example 1 was 17.9 mN / m.

[0109] Example 3 The pair of dies used had a blast treatment applied to the entire molding surface of both the upper and lower dies, followed by a 1μm thick glass film coating using dimethylpolysiloxane, a silicon surface coating treatment.The measured values ​​of the arithmetic mean roughness Ra and maximum height Rz over multiple sections of the molding surfaces of both the upper and lower dies were 0.30μm and 2.22μm, respectively.

[0110] The surface free energy calculated in the same manner as in Example 1 was 15.8 mN / m.

[0111] Comparative Example 1 A pair of dies similar to those used in Example 1 was used, except that the entire molding surfaces of both the upper and lower dies were subjected to a blast treatment, no surface coating treatment was performed, and the measured values ​​of the arithmetic mean roughness Ra and maximum height Rz over multiple sections were 1.97 μm and 12.66 μm, respectively.

[0112] The surface free energy calculated in the same manner as in Example 1 was 29.4 mN / m.

[0113] Comparative Example 2 A pair of dies similar to those used in Example 1 was used, except that the entire molding surfaces of both the upper and lower dies were not plated with nickel-PTFE composite plating but were instead blasted, and the measured values ​​of the arithmetic mean roughness Ra and maximum height Rz over multiple sections were 0.76 μm and 5.09 μm, respectively.

[0114] The surface free energy calculated in the same manner as in Example 1 was 31.9 mN / m.

[0115] Comparative Example 3 A pair of dies similar to those used in Example 1 was used, except that the entire molding surfaces of both the upper and lower dies were not plated with nickel-PTFE composite plating but were instead blasted, and the measured values ​​of the arithmetic mean roughness Ra and maximum height Rz over multiple sections were 0.40 μm and 2.91 μm, respectively.

[0116] The surface free energy calculated in the same manner as in Example 1 was 32.1 mN / m.

[0117] Comparative Example 4 The pair of dies used had both the upper and lower molds with a blast treatment applied to the entire molding surface, followed by a PTFE treatment (fluorine surface treatment) with a film thickness of 30 μm. The measured values ​​of the arithmetic mean roughness Ra and maximum height Rz of multiple sections for the molding surfaces of both the upper and lower molds were 2.14 μm and 11.83 μm, respectively.

[0118] The surface free energy calculated in the same manner as in Example 1 was 15.8 mN / m.

[0119] (Evaluation method) <Method of producing press molded body> Using a tabletop plunger-type melt extrusion machine (manufactured by Nakatsuji Mold Industry 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 a molten resin at 160°C. The molten resin of P3HB3HH was then extruded into a lower mold previously heated to an arbitrary temperature, thereby supplying the molten resin of P3HB3HH to the lower mold. Next, the lower mold to which the molten resin of P3HB3HH was supplied was closed by an upper mold previously heated to an arbitrary temperature, thereby supplying the molten resin between the pair of molds. The pair of molds to which the molten resin of P3HB3HH was supplied was subjected to heat pressing at an arbitrary press molding pressure for a press time of 10 seconds using a heat press molding device (manufactured by Mikado Technos Co., Ltd., VS38-2525). The pair of dies after the hot pressing was immediately sandwiched between upper and lower cooling plates at a temperature of 25°C, and press molding was performed by performing a cooling press with a pressure of 30 kN and a press time of 300 seconds. After press molding, the dies were opened and the press molded body was removed.

[0120] <Evaluation of formability by reducing press molding pressure> The above-mentioned method for producing a press-molded body was carried out using a pair of dies of Examples 1 to 3 and Comparative Examples 1 to 4. In each production method, the heating temperature of the upper die and the lower die was set to 150°C, and the press molding pressure by the hot press molding device was set to 150kN, 125kN, 100kN, 75kN, and 50kN, respectively, to produce a press-molded body.

[0121] The film thickness of the press-molded bodies obtained using the dies of Examples 1 to 3 and Comparative Examples 1 to 4 was measured, and film thickness defects relative to the design film thickness of 0.25 mm for the press-molded bodies were evaluated as follows. Good: Film thickness less than 0.26 mm Defective: Film thickness 0.26 mm or more.

[0122] The evaluation results are shown in Table 1.

[0123] [Table 1]

[0124] From the results in Table 1, it can be seen that lowering the press molding pressure increases the thickness of the obtained press molded body, and thickness defects tend to occur more easily. The upper limit of the press molding pressure at which thickness defects do not occur was 150 kN in Comparative Example 1, 125 kN in Comparative Examples 2 and 3, and 100 kN in Comparative Example 4.

[0125] In contrast, the upper limit of the press molding pressure at which the film thickness of the press-molded body did not become defective was 75 kN in Examples 1 and 2, and 50 kN in Example 3.

[0126] Compared with the method using a pair of dies in Comparative Examples 1 to 4, the method using a pair of dies in Examples 1 to 3 made it possible to perform molding without causing film thickness defects even when the press molding pressure was lowered.

[0127] <Evaluation of moldability by reducing the heating temperature of the upper and lower dies> The above-mentioned method for producing a press-molded body was carried out using a pair of dies of Examples 1 to 3 and Comparative Examples 1 to 4. In each production method, the press molding pressure by the hot press machine was set to 125 kN, and the heating temperatures of the upper die and the lower die were set to 150°C, 135°C, 120°C, and 105°C, respectively, to produce the press-molded body.

[0128] The film thickness of the press-molded bodies obtained using the dies of Examples 1 to 3 and Comparative Examples 1 to 4 was measured, and film thickness defects relative to the design film thickness of 0.25 mm for the press-molded bodies were evaluated as follows. Good: Film thickness less than 0.26 mm Defective: Film thickness 0.26 mm or more.

[0129] The evaluation results are shown in Table 2.

[0130] [Table 2]

[0131] From the results in Table 2, it can be seen that lowering the heating temperature of the upper and lower dies (hereinafter referred to as the die heating temperature) tends to increase the thickness of the obtained press-molded body, making it more likely that thickness defects will occur. In Comparative Example 1, thickness defects occurred even at a die heating temperature of 150°C. The upper limit of the die heating temperature at which thickness defects do not occur was 150°C in Comparative Examples 2 and 3, and 135°C in Comparative Example 4.

[0132] In contrast, in Examples 1 to 3, the upper limit of the die heating temperature at which no film thickness defects occurred was 120°C.

[0133] Thus, compared with the method using a pair of dies in Comparative Examples 1 to 4, the method using a pair of dies in Examples 1 to 3 was capable of molding without causing film thickness defects even when the die heating temperature was lowered.

[0134] <Evaluation of mold opening force (evaluation of mold releasability)> The above-mentioned method for producing a press-molded body was carried out using a pair of dies of Examples 1 to 3 and Comparative Examples 1 to 4. In each production method, the heating temperature of the upper die and the lower die was set to 150°C, the press molding pressure by the heat press molding device was set to 150kN, and the press time was 10 seconds. Regarding the mold releasability of the press-molded bodies produced by the production method using a pair of dies of Examples 1 to 3 and Comparative Examples 1 to 4, the maximum force (mold opening force) required to separate the upper die and the lower die after press molding was measured using a crane scale. The mold releasability was evaluated based on the relative values ​​of the mold opening forces of Examples 1, 2, and 3 when the mold opening force of Comparative Example 1 was set to 100.

[0135] The evaluation results are shown in Table 3.

[0136] [Table 3]

[0137] Regarding the evaluation results of the mold opening force, as is clear from the results shown in Table 3, the mold opening force of the press-molded body of Comparative Example 1 was 127kgf (relative value 100), the mold opening force of Comparative Example 2 was 10kgf (relative value 7.9), the mold opening force of Comparative Example 3 was 6kgf (relative value 4.7), and the mold opening force of Comparative Example 4 was 4kgf (relative value 3.1).

[0138] In contrast, the mold opening force for the press-molded body of Example 1 was 2kgf (relative value 1.6), the mold opening force for the press-molded body of Example 2 was 1.7kgf (relative value 1.3), and the mold opening force for the press-molded body of Example 3 was 1.4kgf (relative value 1.1).

[0139] In the methods using a pair of dies in Comparative Examples 1 to 4, the die opening force was large and the demolding properties were poor, so the press-molded body was prone to deformation when demolded, making it difficult to stably produce press-molded bodies.

[0140] In contrast, in the method using a pair of dies in Examples 1 to 3, the die opening force is small and releasability is excellent, so the press-molded body is less likely to deform when released. Therefore, in the method using a pair of dies in Examples 1 to 3, the press-molded body can be stably produced. [Industrial Applicability]

[0141] INDUSTRIAL APPLICABILITY The present invention can be suitably used in the field of production of press molded articles using P3HA resins and other fields. [Explanation of symbols]

[0142] 1 Molten resin generating section 2 Supply section 2a Discharge part 30 Molding section 31 Pair of dies 32 Lower mold 32A Molding surface 33 Upper mold 33A Molding surface 10 Manufacturing equipment (press molding manufacturing equipment)

Claims

1. a heating step of heating a resin composition containing a poly(3-hydroxyalkanoate)-based resin to form a molten resin composition; a resin supplying step of supplying the molten resin composition between a pair of molds by discharging the molten resin composition from a discharge portion; a molding step of pressing and cooling the flowable molten resin composition by closing the pair of dies, The method for producing a press-molded body, wherein the surface free energy of the molding surfaces of the pair of dies is 26.0 mN / m or less.

2. The method for producing a press-molded product according to claim 1 , wherein the molding surfaces of the pair of dies are subjected to a plating treatment for forming a metal coating having a fluororesin dispersed therein.

3. The method for producing a press-molded body according to claim 1 , wherein the molding surfaces of the pair of dies are subjected to a silicon surface coating treatment.

4. The method for producing a press-molded body according to any one of claims 1 to 3, wherein the molding surfaces of the pair of dies have an arithmetic mean roughness Ra in the range of 0.1 μm to 1.0 μm and a maximum height Rz in the range of 0.5 μm to 10.0 μm.

5. The method for producing a press-molded body according to claim 4 , wherein molding surfaces of the pair of dies have been subjected to at least one surface treatment selected from a shot peening treatment and a blasting treatment.

6. 3. The method for producing a press-molded body according to claim 2, wherein the metal constituting the metal coating is at least one metal selected from the group consisting of nickel-based metals, chromium-based metals, iron-based metals, and alumina-based metals.

7. The method for producing a press-molded body according to any one of claims 1 to 3, wherein the press-molded body has a thickness of 0.1 mm to 0.4 mm at a rising portion rising in a pressing direction.

8. The poly(3-hydroxyalkanoate)-based resin is one or more selected from the group consisting of poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), and poly(3-hydroxybutyrate-co-3-hydroxydecanoate). The method for producing a press-molded body according to any one of claims 1 to 3.

9. An apparatus for producing a press-molded product, comprising a pair of dies for filling a molten resin composition containing a poly(3-hydroxyalkanoate)-based resin, a molten resin producing section for heating a poly(3-hydroxyalkanoate)-based resin composition to produce a molten resin composition; a supply section having a discharge section for discharging the molten resin composition and supplying the molten resin composition between the pair of molds by the discharge section; a molding section that closes the pair of dies to press-molde and cool the flowable molten resin composition, An apparatus for manufacturing a press-molded body, wherein the surface free energy of the molding surfaces of the pair of dies is 26.0 mN / m or less.

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