Molding apparatus and method for manufacturing molded products

Abstract

To supply a molten resin composition to a plurality of molding portions of a mold with good quantitativeness.SOLUTION: In a molding apparatus (100) according to the present invention, a supply unit (20) for supplying a molten resin composition to a mold (30) has a plurality of discharge port units (24) corresponding to each of the molding portions (31a) of the mold (30). a) A gear pump (22) is provided for each of the discharge port units (24). Or, b) a multi-port gear pump for supplying the molten resin composition to each of the discharge port units (24) is provided.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a molding apparatus and a method for manufacturing a molded product.

Background Art

[0002] A technique is known in which a resin composition containing a thermoplastic resin is melted to produce a molten resin composition, and the molten resin composition is supplied to a mold and subjected to press molding. In this technique, a compression molding apparatus is used.

[0003] For example, Patent Document 1 discloses a technique for transferring a molten resin composition to a plurality of molds of a compression molding apparatus. In the technique disclosed in Patent Document 1, while adjusting the pressure of the molten resin composition by one gear pump, the molten resin composition is sequentially injected into a plurality of molds via a branch pipe. In the technique disclosed in Patent Document 1, the molten resin composition is sequentially injected into a plurality of molds by opening and closing valves provided in each branch pipe.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the technique disclosed in Patent Document 1, when supplying the molten resin composition to a plurality of molds simultaneously, it is necessary to open a plurality of valves simultaneously. For this reason, due to the different flow paths of the molten resin composition in the plurality of molds, a pressure loss occurs, and there is a problem that the transfer amount of the molten resin composition varies between the plurality of molds.

[0006] One aspect of the present invention aims to realize a molding apparatus and a method for manufacturing a molded product that can supply a molten resin composition to a plurality of molding parts of a mold with good quantification. [Means for solving the problem]

[0007] To solve the above problems, a molding apparatus according to one aspect of the present invention comprises a mold having a plurality of molding sections for molding a molded body, a melting section for melting a resin composition containing a thermoplastic resin to produce a molten resin composition, and a supply section for supplying the molten resin composition to the mold, wherein the supply section has a plurality of discharge ports corresponding to each of the molding sections of the mold, and a) each discharge port is equipped with a gear pump, or b) each discharge port is equipped with a multi-port gear pump for supplying the molten resin composition.

[0008] To solve the above problems, a method for manufacturing a molded article according to one aspect of the present invention comprises a melting step of melting a resin composition containing a thermoplastic resin to produce a molten resin composition, and a supply step of supplying the molten resin composition to a mold having a plurality of molding sections for molding a molded article, wherein the supply step includes supplying the molten resin composition to the mold from a plurality of discharge ports corresponding to each of the molding sections of the mold via a gear pump provided for each discharge port, or a multi-port gear pump that supplies the molten resin composition to each discharge port. [Effects of the Invention]

[0009] According to one aspect of the present invention, a molten resin composition can be supplied quantitatively to multiple molding parts of a mold. [Brief explanation of the drawing]

[0010] [Figure 1] This figure illustrates the schematic configuration of a molding apparatus according to an embodiment of the present invention. [Figure 2] Figure 1 shows a perspective view illustrating another example of the configuration of the lower mold used in the molding apparatus. [Figure 3] Figure 1 is a perspective view showing a schematic configuration of a modified example 1 of the supply unit provided in the molding apparatus. [Figure 4]This is a perspective view showing the schematic configuration of a modified example 2 of the supply unit provided in the molding apparatus shown in Figure 1. [Modes for carrying out the invention]

[0011] 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.

[0012] (Summary of one embodiment of the present invention) As described above, in conventional technology, when supplying molten resin composition to multiple molds simultaneously, there is a problem in that variations occur in the amount of molten resin composition transferred between the multiple molds. Therefore, conventional technology has the problem of difficulty in supplying molten resin composition to multiple molds with good quantitative accuracy.

[0013] In order to solve the above problems, the inventors diligently conducted research and found that by arranging a gear pump at each discharge port that dispenses to multiple molds, it is possible to supply the molten resin composition to the molds with good quantitative accuracy. Similarly, they found that by using a multi-port gear pump, it is possible to supply the molten resin composition to the molds with good quantitative accuracy.

[0014] The molding apparatus according to this embodiment (hereinafter sometimes referred to as "this molding apparatus") comprises a mold having a plurality of molding sections for molding a molded body, a melting section for melting a resin composition containing a thermoplastic resin to produce a molten resin composition, and a supply section for supplying the molten resin composition to the mold, wherein the supply section has a plurality of discharge ports corresponding to each of the molding sections of the mold, and a) each discharge port is equipped with a gear pump, or b) each discharge port is equipped with a multi-port gear pump for supplying the molten resin composition.

[0015] Further, the method for manufacturing a molded product according to the present embodiment (hereinafter sometimes referred to as the present manufacturing method) includes a melting step of melting a resin composition containing a thermoplastic resin to generate a molten resin composition, and a supply step of supplying the molten resin composition to a mold having a plurality of molding parts for molding a molded body. The supply step includes a step of supplying the molten resin composition to the mold through a gear pump provided for each discharge port or a multi-port gear pump that supplies the molten resin composition to each discharge port, corresponding to each molding part of the mold.

[0016] According to the present molding apparatus and the present manufacturing method, the molten resin composition can be supplied to the plurality of molding parts of the mold with good quantification.

[0017] Furthermore, according to the present resin supply method and the present resin supply apparatus, by using biodegradable resins in the ocean (for example, poly(3-hydroxyalkanoate) - based resins (hereinafter sometimes referred to as P3HA - based resins), etc.), it is possible to suppress marine pollution caused by waste, and thereby contribute 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". Hereinafter, the present resin supply method and the present resin supply apparatus will be described in further detail.

[0018] (Molding Apparatus) FIG. 1 is a diagram for explaining the schematic configuration of a molding apparatus 100 according to the present embodiment. As shown in FIG. 1, the molding apparatus 100 includes an extruder 10, a supply unit 20, a mold 30, and a compression molding unit 40. In the molding apparatus 100, the mold 30 for molding a molded body includes a lower mold 31 and an upper mold 32 corresponding to the lower mold 31. A plurality of molding parts 31a for molding a molded body are provided on the lower mold 31. Thus, the molding apparatus 100 is configured to be able to mold a plurality of molded bodies M in a single molding step by the mold 30.

[0019] The extruder 10 corresponds to a melting section that melts a resin composition containing a thermoplastic resin to produce a molten resin composition. In the extruder 10, the resin composition is introduced from the inlet 11. Then, the resin composition introduced from the inlet 11 is melt-kneaded to become a molten resin composition. Note that the melting section is not limited to the extruder 10 shown in FIG. 1, and any device capable of melting the resin composition may be used.

[0020] The supply section 20 is configured to supply the molten resin composition to the mold 30. In the molding apparatus 100, the molten resin composition is supplied to the molding section 31a of the lower mold 31 by the supply section 20. The supply section 20 includes a discharge section 21 that discharges the molten resin composition into the mold 30. The discharge section 21 is provided corresponding to the molding section 31a of the lower mold 31. The number of the discharge sections 21 is the same as that of the molding sections 31a. Also, as shown in FIG. 1, all of the plurality of discharge sections 21 are arranged at the same position in the vertical direction. Further, each of the plurality of discharge sections 21 is provided with an inlet through which the molten resin composition flows in.

[0021] The supply section 20 is configured to transfer the molten resin composition melted by the extruder 10 to the plurality of discharge sections 21. In the supply section 20, for transferring the molten resin composition to the discharge section 21, a known device can be adopted as long as it is configured to be able to transfer the molten resin composition. The transfer device may be a simple pipe (such as a hot hose etc.) connecting the extruder 10 and the discharge section 21.

[0022] Each of the plurality of discharge sections 21 includes a gear pump 22, a motor 23, and a discharge port section 24. The gear pump 22 has a function of transferring the molten resin composition transferred from the extruder 10 to the discharge port section 24 at a constant pressure. As long as the gear pump 22 can transfer the molten resin composition, a known gear pump can be adopted. The motor 23 is a drive source for driving the gear pump 22. The discharge port section 24 is provided at the tip of the discharge section 21. The molten resin composition is discharged from the discharge port section 24 of the discharge section 21.

[0023] Thus, in the molding apparatus 100, the supply unit 20 has a plurality of discharge ports 24 corresponding to each molding section 31a of the mold 30. The supply unit 20 is equipped with a gear pump 22 for each discharge port 24.

[0024] The compression molding unit 40 clamps the mold 30. More specifically, the compression molding unit 40 clamps the lower mold 31 and the upper mold 32 to press-molde the molten resin composition and cool it. The compression molding unit 40 includes a pair of fixing plates 41 and 42 that fix the mold 30 in the vertical direction, and a molding mechanism (not shown) that clamps and opens the mold 30 fixed by the fixing plates 41 and 42.

[0025] In the molding apparatus 100, the molten resin composition produced by the extruder 10 is supplied from the discharge port 24 of the supply unit 20 to the molding sections 31a of the lower mold 31. The lower mold 31, to which the molten resin composition has been supplied, is then transported to the compression molding unit 40. In the compression molding unit 40, the lower mold 31 is fixed together with the upper mold 32 by the fixing plates 41 and 42. The lower mold 31 and the upper mold 32 (mold 30) are then clamped and hot-pressed by the molding mechanism. After the hot-pressing is complete, the mold 30 is cooled. In this way, the molded body M is formed by hot-pressing and cooling using the mold 30. The molded body M can be removed by opening the mold 30 using the molding mechanism. Note that the compression molding unit 40 is not limited to the apparatus shown in Figure 1; any known press molding apparatus capable of clamping and opening the lower mold 31 and the upper mold 32 to which the molten resin composition has been supplied can be used.

[0026] In the molding apparatus 100, the supply unit 20 has a plurality of discharge ports 24 corresponding to each molding section 31a of the mold 30, and each discharge port 24 is equipped with a gear pump 22. Therefore, the gear pump 22 can transfer the molten resin composition to each discharge port 24 at a constant pressure. As a result, even when supplying the molten resin composition to multiple molding sections 31a simultaneously, there is no variation in the amount of molten resin composition transferred among the multiple discharge ports 24. Thus, the molding apparatus 100 can supply the molten resin composition to multiple molding sections 31a with good quantitative accuracy.

[0027] If a conventional thermoplastic resin molten resin composition is used, stopping the motor 23 will stop the gear pump 22 from driving, and the molten resin composition will not be discharged from the discharge port 24. On the other hand, if a thermoplastic resin with relatively low tackiness (for example, a poly(3-hydroxyalkanoate) resin) is used as the molten resin composition, even if the motor 23 is stopped and the gear pump 22 is stopped, there is a risk that the molten resin composition remaining in the discharge port 24 will fall and be supplied to the molding section 31a of the lower mold 31. As a result, there is a possibility that there will be some variation in the amount of molten resin composition transferred to multiple molding sections 31a. Even when a thermoplastic resin molten resin composition with relatively low tackiness is used, from the viewpoint of supplying the molten resin composition to multiple molding sections 31a with good quantitative accuracy, it is preferable that the supply section 20 intermittently discharges the molten resin composition from the discharge port 24. That is, it is preferable that the discharge port 24 is configured to intermittently discharge the molten resin composition.

[0028] For example, as shown in Figure 1, it is preferable that the discharge port 24 is equipped with an on / off nozzle 24a. The on / off nozzle 24a has the function of blocking the molten resin composition that is continuously supplied from the extruder 10. The on / off nozzle 24a comprises a nozzle body through which the molten resin composition passes, and an on / off mechanism that opens or closes the nozzle body. By alternately closing and opening the nozzle body using the on / off mechanism, the on / off nozzle 24a intermittently discharges the molten resin composition. The on / off nozzle 24a can employ a conventionally known configuration, for example, a shut-off nozzle with a spring-type or needle-type on / off operating principle, and a nozzle with a small cavity at the tip (so-called zero cavity) is preferred.

[0029] According to the molding apparatus 100, even if the gear pump 22 stops driving, the opening and closing nozzle 24a of the discharge port 24 cuts off the molten resin composition that is continuously supplied from the extruder 10, thus preventing the molten resin composition remaining in the discharge port 24 from falling into the molding section 31a. For this reason, even when using a molten resin composition of a thermoplastic resin with relatively low tackiness, the molten resin composition can be supplied to multiple molding sections 31a with good quantitative accuracy.

[0030] Furthermore, from the viewpoint of ensuring smooth intermittent discharge of the molten resin composition, it is preferable that the gear pump 22 is driven in conjunction with the opening and closing of the opening / closing nozzle 24a. That is, the motor 23, which is the drive source for the gear pump 22, is linked to the opening and closing mechanism of the opening / closing nozzle 24a. In this configuration, the gear pump 22 is driven in conjunction with (I) the opening of the opening / closing nozzle 24a by the opening / closing mechanism, and (II) the closing of the opening / closing nozzle 24a by the opening / closing mechanism.

[0031] The molding apparatus 100 offers the advantage of supplying the molten resin composition to multiple molding sections 31a with high quantitative accuracy, as well as the advantage of supplying the molten resin composition to multiple molding sections 31a simultaneously. For example, by setting the timing of the drive of the gear pump 22 by the motor 23 to be the same in multiple discharge sections 21, the molten resin composition can be supplied to multiple molding sections 31a simultaneously.

[0032] With the molding apparatus 100, since the molten resin composition can be supplied to multiple molding sections 31a simultaneously, there is no time difference between the supply of the molten resin composition to the molding section 31a and the press molding by the compression molding section 40, thus reducing variations in the quality of the molded body M. Furthermore, since the press molding can be completed in a short time from the supply of the molten resin composition, the molding cycle can be accelerated. The above effects are effective when using a thermoplastic resin material that has properties that are highly time-dependent (sensitive to the passage of time), such as crystallization. In particular, the above effects are effective when using a poly(3-hydroxyalkanoate) resin as the thermoplastic resin.

[0033] The mold 30 used in the molding apparatus 100 had a configuration in which multiple molding sections 31a were formed in a single lower mold 31. However, the mold 30 is not limited to the configuration shown in Figure 1, and any configuration in which multiple molding sections 31a are formed is acceptable. Figure 2 is a perspective view showing another example of the configuration of the lower mold used in the molding apparatus 100.

[0034] As shown in Figure 2, the lower mold 31A is composed of a plurality of lower mold elements 31b. A molding section 31a is formed in each of the plurality of lower mold elements 31b. Even with a molding apparatus equipped with a lower mold 31A, the molten resin composition can be supplied to the plurality of molding sections 31a with good quantitative accuracy.

[0035] (Variation example 1 of the supply department) A modified example of the supply unit 20 shown in Figure 1 will be described. Figure 3 is a perspective view showing the schematic configuration of the supply unit 20A as modified example 1. Note that the discharge port is omitted in Figure 3.

[0036] As shown in Figure 3, the arrangement of the discharge sections 21 in the supply section 20A differs from that of the supply section 20 shown in Figure 1. In the supply section 20A, the discharge sections 21 are not all located at the same position in the vertical direction. Multiple discharge sections 21 are arranged in a staggered pattern.

[0037] Specifically, in the vertical direction, multiple discharge units 21 are arranged in multiple stages. The positional relationship between the multiple discharge units 21 is as follows: that is, the straight line connecting any discharge unit 21 located in a predetermined stage and the molding unit 31a corresponding to that discharge unit 21 does not pass through any of the discharge units 21 located in stages below the predetermined stage.

[0038] In the positional relationship of the discharge sections 21 shown in Figure 3, the straight line connecting any discharge section 21 located in the second stage in the vertical direction to its corresponding molding section 31a does not pass through any of the discharge sections 21 located in the first stage.

[0039] Even with the configuration of the supply unit 20A, the molten resin composition can be supplied to multiple molding units 31a with good quantitative accuracy. In particular, when the installation space for the discharge unit 21 is limited, the arrangement of the discharge unit 21 as in the supply unit 20A is effective.

[0040] (Variation example 2 of the supply section) Further modifications of the supply unit 20 shown in Figure 1 will be described. Figure 4 is a perspective view showing the schematic configuration of supply unit 20B as modification 2. Note that the discharge port is omitted in Figure 4.

[0041] As shown in Figure 4, the supply unit 20B differs from the supply unit 20 shown in Figure 1 in that it includes a multi-port gear pump 22B and a motor 23B.

[0042] The multi-port gear pump 22B has multiple discharge ports, and is configured to supply the molten resin composition to each discharge port. The multi-port gear pump 22B is equipped with multiple pump mechanisms for simultaneously transferring a fixed amount to the multiple discharge ports. These multiple pump mechanisms are composed of multiple gear elements 22a combined together. The motor 23B is a drive source that drives the gear elements 22a of the pump mechanisms. The multi-port gear pump 22B also has one inlet into which the molten resin composition generated by the melting section flows.

[0043] In the multi-port gear pump 22B, when the pump mechanism consisting of multiple gear elements 22a is driven by the motor 23B, the molten resin composition flows in from the inlet and is discharged simultaneously from multiple outlets. The multi-port gear pump 22B is a single pump device, yet it is configured to have multiple pump mechanisms within the device that simultaneously transfer a quantitative amount of molten resin composition to multiple outlets.

[0044] Therefore, a molding apparatus equipped with a supply unit 20B is particularly effective when supplying a molten resin composition to multiple molding units 31a simultaneously. The multi-port gear pump 22B can be a known device, such as the multi-port gear pump disclosed in Japanese Patent No. 4980504. The multi-port gear pump disclosed on the webpage "https: / / www.ipros.jp / product / detail / 2000316958" can also be used as the multi-port gear pump 22B.

[0045] (Method of manufacturing molded products) This manufacturing method comprises a melting step and a supply step. In the melting step, a resin composition containing a thermoplastic resin is melted to produce a molten resin composition. In the supply step, the molten resin composition is supplied to a mold having multiple molding sections for forming a molded article. In this manufacturing method, the supply step includes supplying the molten resin composition to the mold from a plurality of discharge ports corresponding to each of the molding sections of the mold, via (i) a gear pump provided for each discharge port, or (ii) a multi-port gear pump that supplies the molten resin composition to each discharge port. This manufacturing method is not particularly limited as long as it has the steps described above, but an example is a method for manufacturing molded articles using the molding apparatus described above.

[0046] In the melting step described above, a resin composition containing a thermoplastic resin is melted to produce a molten resin composition. The method for melting the resin composition can be any conventionally known method, as long as it can form a molten resin composition containing a thermoplastic resin. Preferably, the melting step includes a melt-kneading step in which the resin composition containing the thermoplastic resin is melt-kneaded.

[0047] 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 are, for example, (a1) and (a2) below. Methods include: (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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] In the melt-mixing process, for example, if the thermoplastic resin is a P3HA-based resin, the temperature at which the resin composition is melt-mixed cannot be specified in general, as it depends on the physical properties of the P3HA-based resin (melting point, weight-average molecular weight, etc.) and the type of additive used. Regarding the temperature at which the resin composition is melt-mixed, for example, the temperature of the molten resin composition discharged from the discharge port (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-based resin may be generated. On the other hand, if the composition temperature is 180°C or higher, the P3HA-based resin may undergo thermal decomposition.

[0052] In the above supply step, the molten resin composition is supplied to a mold having multiple molding sections for forming a molded body. The gear pump or multi-port gear pump used in the above supply step can be the gear pump 22 or multi-port gear pump 22B described in the (molding apparatus) section. According to this manufacturing method, the above supply step includes a step of supplying the molten resin composition to the mold from a plurality of discharge ports corresponding to each of the molding sections of the mold, via (i) a gear pump provided for each of the discharge ports, or (ii) a multi-port gear pump that supplies the molten resin composition to each of the discharge ports. Therefore, the molten resin composition can be supplied to multiple molding sections with good quantitative accuracy.

[0053] Furthermore, especially for molten resin compositions with relatively low tackiness, it is preferable that the supply process includes a step A in which the molten resin composition is intermittently discharged from the discharge port. This allows for precise quantitative supply of the molten resin composition to multiple molding sections. In step A, it is preferable to discharge the molten resin composition by blocking the molten resin composition continuously supplied from the melting process using an on / off nozzle provided at the discharge port. The on / off nozzle used in step A can be the on / off nozzle 24a described in the (molding apparatus) section.

[0054] Furthermore, the intermittent dispensing of the molten resin composition may be performed periodically, with the dispensing operation being executed and stopped alternately, or it may be performed aperiodically. When the dispensing operation is performed periodically, the period of execution and stopping of the dispensing operation can be appropriately set according to the composition temperature, the tackiness of the molten resin composition, etc.

[0055] For example, when the thermoplastic resin is a P3HA-based resin, in the intermittent dispensing of the molten resin composition, the dispensing operation is preferably stopped every 1 to 30 seconds, and more preferably every 1 to 15 seconds. Furthermore, the stop time of the dispensing operation is preferably 1 to 15 seconds, and more preferably 1 to 5 seconds. This has the advantage of preventing the deterioration of the resin properties of the molten resin composition of the 3HA-based resin due to heat.

[0056] The present manufacturing method preferably further includes a compression molding step for clamping the above-mentioned mold. More specifically, in the compression molding step, a hot press molding machine is used to clamp the lower mold and the upper mold and press-molde the molten resin composition. Then, the press molding is carried out by cooling the mold after the hot press is completed. After press molding, the mold is opened to obtain the press-molded product. The compression molding apparatus used in the above-mentioned compression molding step may be the compression molding section 40 described in the (molding apparatus) section.

[0057] (thermoplastic resin) The resin composition used in this manufacturing method includes a thermoplastic resin. The thermoplastic resin is not particularly limited. Preferred thermoplastic resins include general-purpose resins such as polypropylene, polyethylene, polyvinyl chloride, polyvinyl acetate, polyacetal, polycarbonate, polyamide, acrylonitrile, butadiene, polystyrene, and acrylic polymers, as well as biodegradable resins such as P3HA resins, polylactic acid, polyglycolic acid, polybutylene succinate, polybutylene succinate adipate, polybutylene adipate terephthalate, polybutylene succinate terephthalate, and polycaprolactone. Furthermore, it is preferable that the resin composition used in this manufacturing method includes a thermoplastic resin that can be used in press molding.

[0058] In particular, the thermoplastic resin used in this manufacturing method is preferably a P3HA resin. In this specification, "P3HA resin" means a biodegradable aliphatic polyester (preferably a polyester that does not contain aromatic rings). A P3HA resin is 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.

[0059] 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 constitute 94.5 to 98.5 mol%, preferably 95.0 to 98.5 mol%, more preferably 96.0 to 98.5 mol%, and even more preferably 96.5 to 98.0 mol% of the total repeating units (100 mol%).

[0060] When the composition ratio of 3HB repeating units is 94.5 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 98.5 mol% or lower, the melting point is below the thermal decomposition temperature, enabling stable and continuous production. The monomer composition ratio of the P3HA resin can be measured by gas chromatography, etc. (see, for example, International Publication No. 2014 / 020838).

[0061] More specifically, P3HA-based resins include copolymers of 3HB with other hydroxyalkanoates, such as 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).

[0062] Furthermore, P3HA resins produced by microorganisms (microbially produced P3HA resins) are typically P3HA resins composed only of D-isomer (R-isomer) polyhydroxyalkanoic acid 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] The 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 moles, more preferably 68.0 to 88.0 moles, and even more preferably 70.0 to 85.0 moles. The resin composition further contains the second P3HA-based resin, resulting in superior toughness of the molded article.

[0068] 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 the aforementioned P3HA-based resin.

[0069] 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 resin composition in this manufacturing method.

[0070] The resin composition may contain other resins besides P3HA resins, as long as they do not impair the effects of the present invention. 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.

[0071] 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.

[0072] The resin composition does not necessarily have to contain an inorganic filler, but it is preferable that it further contains an inorganic filler. The inclusion of an inorganic filler in the resin composition improves the crystallization rate, resulting in effects such as reduced burrs and improved production cycles.

[0073] 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.

[0074] 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, based on 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.

[0075] Furthermore, the 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.

[0076] 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.

[0077] In other words, one embodiment of the present invention is as follows: <1> A molding apparatus comprising: a mold having a plurality of molding sections for forming a molded body; a melting section for melting a resin composition containing a thermoplastic resin to produce a molten resin composition; and a supply section for supplying the molten resin composition to the mold, wherein the supply section has a plurality of discharge ports corresponding to each of the molding sections of the mold, and a) each discharge port is equipped with a gear pump, or b) each discharge port is equipped with a multi-port gear pump for supplying the molten resin composition. <2> The supply unit intermittently discharges the molten resin composition from the discharge port. <1> The molding apparatus described above. <3> The discharge port is equipped with an opening / closing nozzle that blocks the molten resin composition continuously supplied from the melting section. <1> or <2> The molding apparatus described above. <4> The gear pump is driven in conjunction with the opening and closing of the opening and closing nozzle. <3> The molding apparatus described above. <5> The mold comprises a lower mold and an upper mold corresponding to the lower mold, and the molten resin composition is supplied to the lower mold. <1> ~ <4> A molding apparatus as described in any of the following. <6> Furthermore, it includes a compression molding section for clamping the mold, <1> ~ <5> A molding apparatus as described in any of the following. <7> A method for manufacturing a molded article, comprising: a melting step of melting a resin composition containing a thermoplastic resin to produce a molten resin composition; and a supply step of supplying the molten resin composition to a mold having a plurality of molding sections for molding a molded article, wherein the supply step includes supplying the molten resin composition to the mold from a plurality of discharge ports corresponding to each of the molding sections of the mold via a gear pump provided for each discharge port, or a multi-port gear pump that supplies the molten resin composition to each discharge port. <8> The aforementioned thermoplastic resin is a poly(3-hydroxyalkanoate) resin. <7> A method for manufacturing molded articles as described above. <9> The aforementioned poly(3-hydroxyalkanoate) 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). <8> A method for manufacturing molded articles as described above. [Industrial applicability]

[0078] The present invention can be suitably used, for example, in the field of manufacturing press-molded articles using P3HA-based resins, and in other fields. [Explanation of symbols]

[0079] 10 Extruder 20, 20A, 20B supply section 22 Gear pump 22B Multi-port Gear Pump 24 Discharge port 24a Opening / Closing Nozzle 30 molds 31, 31A Lower mold 31a Molding part 32 Upper mold 40 Compression molding section 100 Molding equipment

Claims

1. A mold having multiple molding sections for forming a molded body, A melting section that melts a resin composition containing a poly(3-hydroxyalkanoate) resin to produce a molten resin composition, The system includes a supply unit for supplying the molten resin composition to the mold, The supply unit has a plurality of discharge ports corresponding to each of the molding sections of the mold, a) Each of the discharge ports is equipped with a gear pump, or b) A multi-port gear pump is provided to supply the molten resin composition to each of the discharge ports, The molding apparatus comprises an opening / closing nozzle that blocks the molten resin composition continuously supplied from the melting section at the discharge port.

2. The molding apparatus according to claim 1, wherein the supply unit intermittently discharges the molten resin composition from the discharge port.

3. The molding apparatus according to claim 1, wherein the gear pump is driven in conjunction with the opening and closing of the opening and closing nozzle.

4. The mold comprises a lower mold and an upper mold corresponding to the lower mold. The molding apparatus according to any one of claims 1 to 3, wherein the molten resin composition is supplied to the lower mold.

5. Furthermore, the molding apparatus according to any one of claims 1 to 4, further comprising a compression molding section for clamping the mold.

6. A melting step to produce a molten resin composition by melting a resin composition containing a poly(3-hydroxyalkanoate) resin, The process includes a supply step of supplying the molten resin composition to a mold having multiple molding sections for forming a molded body, The aforementioned supply process is, A method for manufacturing a molded product, comprising the step of supplying the molten resin composition to the mold via a gear pump provided at each of the multiple discharge ports corresponding to each of the molding sections of the mold, or a multi-port gear pump that supplies the molten resin composition to each of the discharge ports, and an on / off nozzle that shuts off the molten resin composition continuously supplied from the melting process.

7. The method for producing a molded article according to claim 6, wherein the poly(3-hydroxyalkanoate) 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).

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