Method for manufacturing foamed molded products

Abstract

The present invention provides a method for manufacturing a foamed molded article that can provide a foamed molded article in which deformation is prevented or reduced. [Solution] The manufacturing method comprises the steps of: transporting aliphatic polyester resin foam particles from a bunker (1) through a first foam particle transport pipe (51) using a first ejector (41) to a pressure vessel (2); applying internal pressure to the foam particles; and transporting the foam particles with internal pressure applied from the pressure vessel (2) through a second foam particle transport pipe (52) using a second ejector (42) to a hopper (3).

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a foamed molded body.

Background Art

[0002] In recent years, from the perspective of reducing environmental impact, technologies for using aliphatic polyester-based resins, which are biodegradable thermoplastic resins, in foamed molded body applications have been studied (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the conventional technologies as described above had room for further improvement from the perspective of deformation of the foamed molded body.

[0005] One embodiment of the present invention has been made in view of the above problems, and an object thereof is to provide a novel method for manufacturing an aliphatic polyester-based resin foamed molded body that can provide an aliphatic polyester-based resin foamed molded body in which deformation is prevented or reduced.

Means for Solving the Problems

[0006] As a result of intensive studies to solve the above problems, the present inventors have completed the present invention.

[0007] That is, one embodiment of the present invention includes the following configurations. 〔1〕A method for manufacturing an aliphatic polyester-based resin foamed molded body by molding aliphatic polyester-based resin foamed particles using a molding device, (i) The molding apparatus comprises a bunker into which the aliphatic polyester resin foam particles are fed, a pressure vessel, and a hopper for containing the aliphatic polyester resin foam particles, wherein the bunker and the pressure vessel are connected by a first ejector and a first foam particle transport pipe, and the pressure vessel and the hopper are connected by a second ejector and a second foam particle transport pipe. The method for manufacturing the aliphatic polyester resin foam molded article comprises: a transport step (A1) of transporting the aliphatic polyester resin foam particles from the bunker to the pressure vessel using the first ejector through the first foam particle transport pipe; an internal pressure application step of increasing the pressure inside the pressure vessel to apply internal pressure to the aliphatic polyester resin foam particles; a pressure release step of releasing the pressure inside the pressure vessel while containing the aliphatic polyester resin foam particles to which internal pressure has been applied; and a transport step (A2) of transporting the aliphatic polyester resin foam particles to which internal pressure has been applied from the pressure vessel to the hopper using the second ejector through the second foam particle transport pipe, or (ii) The molding apparatus comprises a bunker into which the aliphatic polyester resin foam particles are fed, and a hopper for containing the aliphatic polyester resin foam particles, and does not include a pressure vessel, and the bunker and the hopper are connected by a third ejector and a third foam particle transport pipe, The method for manufacturing an aliphatic polyester resin foam molded article comprises a transport step (B) of transporting the aliphatic polyester resin foam particles from the bunker to the hopper using the third ejector, through the third foam particle transport pipe. [2] The method for producing an aliphatic polyester resin foam molded article according to [1], wherein the transport atmosphere temperature in one or more transport steps selected from the group consisting of transport step (A1), transport step (A2), and transport step (B) is 5°C to 60°C. [3] The method for producing an aliphatic polyester resin foam molded article according to [1] or [2], wherein the aliphatic polyester resin foam particles are poly(3-hydroxyalkanoate) resin foam particles. [Effects of the Invention]

[0008] One embodiment of the present invention provides a novel method for manufacturing an aliphatic polyester resin foam molded article, which can provide an aliphatic polyester resin foam molded article in which deformation is prevented or reduced. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram showing an example of the general configuration of a molding apparatus used in a method for manufacturing a foamed molded article according to one embodiment of the present invention. [Figure 2] This is a schematic diagram showing an example of the general configuration of a molding apparatus used in a method for manufacturing a foamed molded article according to one embodiment of the present invention. [Figure 3] This is a schematic diagram of a foamed molded article according to an embodiment of the present invention. [Modes for carrying out the invention]

[0010] One embodiment of the present invention is described below, but the present invention is not limited thereto. The present invention is not limited to the configurations described below, and various modifications are possible within the scope of the claims. Furthermore, embodiments or examples obtained by combining the technical means disclosed in different embodiments or examples are also included in the technical scope of the present invention. Moreover, new technical features can be formed by combining the technical means disclosed in each embodiment. All academic and patent documents mentioned herein are incorporated herein by reference. Furthermore, unless otherwise specified herein, "A to B" representing a numerical range means "A or greater (including A and greater than A) and B or less (including B and less than B)."

[0011] In this specification, repeating units derived from the X monomer may be referred to as "X units." Repeating units can also be called constituent units.

[0012] [1. Technical Concept of One Embodiment of a Certain Entity] One of the processes involved in molding thermoplastic resin foam particles (for example, in-mold foaming) is the transport process, in which the thermoplastic resin foam particles are transported from a bunker to a hopper through a foam particle transport pipe.

[0013] Conventional thermoplastic resin foam particles, such as polystyrene-based and polyolefin-based resin foam particles, are transported using high-capacity blowers during the transport process. For example, when transporting thermoplastic resin foam particles from a bunker to a hopper through a foam particle transport pipe, a blower is installed in the middle of the foam particle transport pipe to allow air to be blown in the direction from the bunker to the hopper. Thermoplastic resin foam particles introduced into the bunker are sucked into the blower through the foam particle transport pipe connected to the bunker. After that, the thermoplastic resin foam particles are transported through the blower to a foam particle transport pipe connected to the blower, and then transported to the hopper along the airflow through the foam particle transport pipe.

[0014] On the other hand, the inventors have newly discovered that when transporting aliphatic polyester resin foam particles using a blower as in the conventional method, a new problem exists: excessive deformation occurs in the resulting foamed molded articles. In order to solve the above problem, the inventors diligently investigated the cause of deformation in the foamed molded articles and newly discovered that the deterioration (increase) of the open-cell ratio of aliphatic polyester resin foam particles during the transport process from the bunker to the hopper is a factor in the excessive deformation that occurs in the resulting foamed molded articles.

[0015] As a cause of the deterioration of the closed cell ratio of such aliphatic polyester resin foam particles, it is considered that the aliphatic polyester resin foam particles are brittle compared to conventional thermoplastic resin foam particles. More specifically, when transporting aliphatic polyester resin foam particles in the same manner as transporting conventional thermoplastic resin foam particles, when the aliphatic polyester resin foam particles pass through the blower, the aliphatic polyester resin foam particles may collide with the blades (sometimes referred to as "impellers") driven inside the blower. It is considered that such a collision applies a strong impact to the aliphatic polyester resin foam particles, and the air bubbles in the outer layer of the aliphatic polyester resin foam particles are destroyed due to the impact.

[0016] The inventors who obtained the above findings thought that if it was possible to suppress the deterioration of the closed cell ratio in the transportation process of aliphatic polyester resin foam particles, it would be possible to provide an aliphatic polyester resin foam molded article with deformation prevented or reduced. As a result of further intensive studies based on such findings, the inventors independently found the following new findings and completed the present invention. That is, by using an ejector in the transportation of aliphatic polyester resin foam particles, the transportation method of passing through the blower is changed to the transportation method of passing through the ejector. As a result, there is a new finding that it is possible to provide an aliphatic polyester resin foam molded article with deformation prevented or reduced.

[0017] The reason why an aliphatic polyester-based resin foam molded article with deformation prevented or reduced can be provided by changing the transportation method from passing through a blower to passing through an ejector is not clear, but the present inventor speculates as follows. Since there are no rotating physical blades in the ejector, by changing the transportation method from passing through a blower to passing through an ejector, physical impact on the aliphatic polyester-based resin foam particles can be prevented or significantly reduced. Thereby, deterioration of the closed-cell ratio of the aliphatic polyester-based resin foam particles in the transportation process can be suppressed, and as a result, an aliphatic polyester-based resin foam molded article with deformation prevented or reduced can be provided. Note that one embodiment of the present invention is not limited to such speculation.

[0018] One aspect of the present invention can be conceived in consideration of the unique physical properties of the aliphatic polyester-based resin foam particles found by the present inventors and the new problems caused by such physical properties. Therefore, it cannot be easily corresponded from the prior art premised on molding conventional thermoplastic resin particles that do not have such physical properties, and it can be said that it is a novel method different from the prior art in technical idea.

[0019] [2. Manufacturing method of foam molded article] A manufacturing method of a foam molded article according to an embodiment of the present invention is a manufacturing method of an aliphatic polyester-based resin foam molded article for molding aliphatic polyester-based resin foam particles using a molding apparatus, (i) The molding apparatus comprises a bunker into which the aliphatic polyester resin foam particles are introduced, a pressure vessel, and a hopper for containing the aliphatic polyester resin foam particles, wherein the bunker and the pressure vessel are connected by a first ejector and a first foam particle transport pipe, and the pressure vessel and the hopper are connected by a second ejector and a second foam particle transport pipe, and the method for manufacturing the aliphatic polyester resin foam molded article is to transport the first foam particles from the bunker to the pressure vessel using the first ejector A method comprising: a transport step (A1) of transporting the aliphatic polyester resin foam particles through a pipe; an internal pressure application step of increasing the pressure inside the pressure vessel to apply internal pressure to the aliphatic polyester resin foam particles; a pressure release step of releasing the pressure inside the pressure vessel while containing the aliphatic polyester resin foam particles to which internal pressure has been applied; and a transport step (A2) of transporting the aliphatic polyester resin foam particles to which internal pressure has been applied from the pressure vessel to the hopper using the second ejector through the second foam particle transport pipe, or (ii) The molding apparatus comprises a bunker into which the aliphatic polyester resin foam particles are introduced, and a hopper for containing the aliphatic polyester resin foam particles, and does not include a pressure vessel, and the bunker and the hopper are connected by a third ejector and a third foam particle transport pipe, and the method for manufacturing the aliphatic polyester resin foam molded article is a transport step (B) in which the aliphatic polyester resin foam particles are transported from the bunker to the hopper using the third ejector and through the third foam particle transport pipe.

[0020] In this specification, "a method for producing a foamed molded article according to one embodiment of the present invention" may be referred to as "this manufacturing method," and "aliphatic polyester resin foam particles" may be referred to as "foam particles." Furthermore, the foamed molded article obtained by this manufacturing method can also be called an "aliphatic polyester resin foamed molded article." In this specification, "aliphatic polyester resin foamed molded article" may be referred to as a "foamed molded article."

[0021] Because this manufacturing method has the above-described configuration, it has the advantage of being able to provide an aliphatic polyester resin foam molded article in which deformation is prevented or reduced.

[0022] Furthermore, because this manufacturing method uses aliphatic polyester resin, which is a biodegradable resin, the resulting foamed molded product can reduce soil and / or marine pollution from disposal. This is expected to contribute to achieving Sustainable Development Goals (SDGs), such as Goal 12, "Ensure sustainable consumption and production patterns," and / or Goal 14, "Conserve and sustainably use the oceans, seas and marine resources for sustainable development."

[0023] First, we will explain the materials (raw materials) used in this manufacturing method.

[0024] <Foaming particles> The foamed particles used in this manufacturing method are obtained by foaming aliphatic polyester resin particles obtained using an aliphatic polyester resin. Furthermore, the foamed molded article is obtained by molding the foamed particles (for example, in-mold foaming). It can also be said that the foamed particles are made by foaming aliphatic polyester resin particles containing an aliphatic polyester resin.

[0025] Aliphatic polyester resin particles, which are the raw materials for foamed particles, can be obtained, for example, by the following method: (1) Mix an aliphatic polyester resin with a foam regulator such as talc and other additives such as fatty acid amide to obtain a mixture; (2) The mixture obtained is melt-kneaded while heating, for example using an extruder, to obtain a molten resin composition; (3) After water cooling, the obtained resin composition is cut to obtain aliphatic polyester resin particles.

[0026] The aliphatic polyester resin foam particles can be obtained, for example, by foaming aliphatic polyester resin particles using the following method: (1) Mix a dispersion medium such as water, aliphatic polyester resin particles, and, if necessary, a crosslinking agent such as 1,1-di(t-butylperoxy)cyclohexane (TBCH), a dispersant such as tricalcium phosphate, and a dispersion aid such as sodium alkanesulfonate in a container; (2) While stirring the resulting mixture with a stirrer, add a foaming agent such as carbon dioxide, ethanol, and mixed butane (e.g., a mixture of n-butane and isobutane) to the container to prepare a dispersion; (3) Heat the dispersion to the foaming temperature, and if necessary, increase the pressure inside the container to the foaming pressure; (4) Maintain the temperature and pressure inside the container at or near the foaming temperature and foaming pressure, respectively, for a certain period of time; (5) Next, foaming particles are obtained by releasing the dispersion in the container into atmospheric pressure. Here, from (2) to (5) above, the dispersion (mixture) in the container is continuously stirred, for example, with a stirrer. The steps (1) and (2) above are sometimes collectively referred to as the "dispersion step".

[0027] The foamed particles obtained in this way may be washed with an aqueous solution of sodium hexametaphosphate or the like, if necessary.

[0028] Alternatively, foamed particles may be obtained by impregnating the aliphatic polyester resin particles with a foaming gas (foaming agent) in a pressure vessel, and then introducing the aliphatic polyester resin particles containing the foaming agent into a foaming machine and foaming them with water vapor or the like.

[0029] The shape of the foam particles is not particularly limited, but may be spherical or substantially spherical, for example.

[0030] (Aliphatic polyester resin) As described above, foamed particles are obtained by foaming aliphatic polyester resin particles containing an aliphatic polyester resin. In other words, aliphatic polyester resin foamed particles contain an aliphatic polyester resin as a resin component. In this specification, "resin component" in foamed particles refers to the resin component that substantially constitutes the foamed particles, excluding foaming agents, foam regulators, and other additives.

[0031] The resin component of the foamed particles contains, for example, more than 50% by weight of aliphatic polyester resin, more preferably 60% or more by weight, more preferably 70% or more by weight, more preferably 80% or more by weight, even more preferably 90% or more by weight, even more preferably 95% or more by weight, and particularly preferably 100% by weight. In other words, it is particularly preferable that the resin component of the aliphatic polyester resin foamed particles consists only of aliphatic polyester resin. The higher the content of aliphatic polyester resin in the resin component of the foamed particles, the more effective it is at suppressing soil contamination from the disposal of the resulting foamed molded product.

[0032] Examples of aliphatic polyester resins include one or more selected from the group consisting of poly(3-hydroxyalkanoate) resins, polylactic acid, polyethylene succinate, polybutylene succinate, polyethylene adipate, polybutylene adipate, polyhexamethylene adipate polyethylene succinate adipate, polybutylene succinate adipate, polyethylene adipate terephthalate, polybutylene adipate terephthalate, polyethylene succinate terephthalate, polybutylene succinate terephthalate, polyethylene oxalate, polybutylene oxalate, polyneopentyl oxalate, polyethylene sebacate, polybutylene sebacate, polyhexamethylene sebacate, and polycaprolactone.

[0033] Among aliphatic polyester resins, poly(3-hydroxyalkanoate) resins, which are biodegradable in both soil and marine environments, are preferred. In other words, it is preferable that the resin component of the foamed particles contains a poly(3-hydroxyalkanoate) resin.

[0034] The resin component of the foamed particles preferably contains more than 50% by weight of poly(3-hydroxyalkanoate) resin in 100% by weight of the resin component. In this specification, foamed particles containing more than 50% by weight of "X" resin in 100% by weight of the resin component may be referred to as X resin foamed particles. For example, foamed particles containing more than 50% by weight of poly(3-hydroxyalkanoate) resin in 100% by weight of the resin component may also be referred to as poly(3-hydroxyalkanoate) resin foamed particles. Aliphatic polyester resin foamed particles are preferably poly(3-hydroxyalkanoate) resin foamed particles. This configuration has the advantage of being able to suppress (reduce) soil and marine pollution caused by the disposal of foamed molded products.

[0035] The resin component of the foamed particles more preferably contains 60% by weight or more of poly(3-hydroxyalkanoate) resin, more preferably 70% by weight or more, more preferably 80% by weight or more, even more preferably 90% by weight or more, even more preferably 95% by weight or more, and particularly preferably 100% by weight. In other words, it is particularly preferable that the resin component of the foamed particles consists solely of poly(3-hydroxyalkanoate) resin. The higher the content of poly(3-hydroxyalkanoate) resin in the resin component of the aliphatic polyester resin foamed particles, the more advantageous it is to suppress soil and / or marine pollution caused by the disposal of the resulting foamed molded product.

[0036] (Poly(3-hydroxyalkanoate) resin) In this specification, "poly(3-hydroxyalkanoate) resin" may be referred to as "poly(3-hydroxyalkanoate)" or "P3HA". P3HA will be described below.

[0037] P3HA is a polymer having a 3-hydroxyalkanoate unit as an essential constituent unit (monomer unit). In this specification, "3-hydroxyalkanoate" may also be referred to as "3HA". Specifically, a polymer containing the repeating unit shown in the following general formula (1) is preferred as P3HA: [-CHR-CH2-CO-O-]···(1). In general formula (1), R is C n H 2n+1 R represents an alkyl group, where n is an integer from 1 to 15. Examples of R include linear or branched alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, and hexyl groups. n is preferably 1 to 10, and more preferably 1 to 8.

[0038] As for P3HA, P3HA produced from microorganisms is particularly preferred. P3HA produced from microorganisms is poly[(R)-3HA] in which all 3HA units are (R)-3HA.

[0039] P3HA preferably contains 50 mol% or more of 3HA units (particularly the repeating unit of general formula (1)) out of 100 mol% of the total repeating units of P3HA, more preferably 70 mol% or more, and even more preferably 80 mol% or more. Furthermore, the repeating units (monomer units) may consist only of 3HA units, or in addition to 3HA units, it may also contain repeating units derived from monomers other than 3HA (for example, 4-hydroxyalkanoate units).

[0040] Specific examples of 3HA units include 3-hydroxybutyrate units, 3-hydroxyvalerate units, and 3-hydroxyhexanoate units. 3-hydroxybutyrate has a melting point and tensile strength close to that of propylene. Therefore, P3HA according to one embodiment of the present invention preferably contains 3-hydroxybutyrate units. In this specification, "3-hydroxybutyrate" may also be referred to as "3HB".

[0041] P3HA preferably contains 80 mol% or more of 3HB units (monomer units) out of 100 mol% of the total repeating units of P3HA, and more preferably 85 mol% or more. As P3HA, polymers (polymers produced by microorganisms) that contain 3HB units and in which all 3HB units are (R)-3HB are particularly preferred.

[0042] When P3HA contains two or more repeating units, the monomers from which the repeating units other than the most abundant one originate are referred to as comonomers. In this specification, "repeating units derived from comonomers" may also be referred to as "comonomer units."

[0043] The comonomer is not particularly limited, but 3-hydroxyhexanoate (hereinafter sometimes referred to as 3HH) or 4-hydroxybutyrate (hereinafter sometimes referred to as 4HB) are preferred.

[0044] Specific examples of P3HA include, for example, poly(3-hydroxybutyrate), poly(3-hydroxypropionate), poly(3-hydroxybutyrate-co-3-hydroxypropionate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (hereinafter sometimes referred to as "P3HB3HV"), poly(3-hydroxybutyrate-co-3-hydroxyvalerate-3-hydroxyhexanoate), and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (hereinafter referred to as "P3HB3HH"). Examples include poly(3-hydroxybutyrate-co-3-hydroxyheptanoate), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), poly(3-hydroxybutyrate-co-3-hydroxynonanoate), poly(3-hydroxybutyrate-co-3-hydroxydecanoate), poly(3-hydroxybutyrate-co-3-hydroxyundecanoate), and poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (hereinafter sometimes referred to as "P3HB4HB"). In particular, from the viewpoint of processability and the physical properties of the foamed molded product, poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), or poly(3-hydroxybutyrate-co-4-hydroxybutyrate) are preferred. In one embodiment of the present invention, the above-mentioned P3HA may be used alone or in combination of two or more types.

[0045] Note that "-co-X" is intended to include the X unit as a comonomer unit.

[0046] P3HA preferably has 3HB units as essential repeating units (constituent units) and also has comonomer units. That is, P3HA is preferably a copolymer having 3HB units and comonomer units. The case in which P3HA has 3HB units and comonomer units will be described. In this case, the ratio of 3HB units to comonomer units (3HB units / comonomer units) in 100 mol% of the total repeating units in P3HA is preferably 99 / 1 (mol% / mol%) to 80 / 20 (mol% / mol%), more preferably 97 / 3 (mol% / mol%) to 80 / 20 (mol% / mol%), and even more preferably 95 / 5 (mol% / mol%) to 85 / 15 (mol% / mol%). If the ratio of comonomer units to 100 mol% of the total repeating units in P3HA is 1 mol% or more, the melt-kneadable temperature range and the thermal decomposition temperature range of P3HA are sufficiently far apart, which has the advantage that the resulting foamed particles have excellent processability. On the other hand, if the ratio of comonomer units to 100 mol% of total repeating units of P3HA is 20 mol% or less, the crystallization of the P3HA-based composition during melt kneading is rapid, resulting in high productivity. P3HA having such ratios of each monomer unit can be produced by methods known to those skilled in the art, for example, according to the method described in International Publication WO2009 / 145164.

[0047] The ratio of each monomer unit in P3HA can be determined by methods known to those skilled in the art, for example, by the method described in International Publication 2013 / 147139.

[0048] In one embodiment of the present invention, the method for producing P3HA is not particularly limited and may be a chemical synthesis method or a microbial method. Among these, the microbial method is preferred. Known methods can be applied to the microbial method for producing P3HA.

[0049] Examples of microorganisms that produce copolymers of 3HB with 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.Bacteriol., 179, p4821-4830 (1997)) is more preferred, as its P3HB3HH productivity has been improved by introducing genes for the P3HA synthase group. In the method for producing P3HA, microbial cells that have accumulated P3HB3HH in their cells by culturing microorganisms such as Alcaligenes eutrophus AC32 strain under appropriate conditions are preferably used. Furthermore, regarding copolymer-producing microorganisms, in addition to those mentioned above, genetically modified microorganisms into which various P3HA synthesis-related genes have been introduced may be used, depending on the P3HA to be produced. Also, the culture conditions of the microorganisms (bacteria) should be optimized, including the type of substrate, according to the P3HA to be produced.

[0050] In one embodiment of the present invention, the method for culturing the microorganism that produces P3HA is not particularly limited, and for example, the method described in International Publication No. WO2019 / 142717 can be used.

[0051] The resin component of the foamed particles may include resins other than aliphatic polyester resins. Examples of resins other than aliphatic polyester resins include polypropylene, polyethylene, polystyrene, modified starch, and modified cellulose.

[0052] The foamed particles may contain, in addition to a resin component including an aliphatic polyester resin, additives, nucleating agents, foam regulators, crosslinking agents, crosslinking aids, foaming agents, dispersants, and dispersing aids that can be used during the manufacture of the aliphatic polyester resin particles and / or foamed particles. The foamed particles may also contain other usable components insofar as they do not hinder the effects of the embodiment of the present invention. Examples of other components 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, nucleating agents, lubricants, mold release agents, water repellents, antibacterial agents, and sliding properties modifiers. Only one of these other components may be included, or two or more may be included. The content of these other components can be appropriately determined by a person skilled in the art depending on the intended use. Regarding the types, amounts, and other methods of use of such additives, foam regulators, crosslinking agents, crosslinking aids, foaming agents, dispersants, dispersing aids, and other components, as an example, the types, amounts, and other methods of use disclosed in International Publication No. 2021 / 002092 can be adopted.

[0053] As a crosslinking agent, organic peroxides are preferred, for example. By using a crosslinking agent in the manufacturing process of aliphatic polyester resin particles and / or foamed particles, crosslinked foamed particles can be obtained. In other words, it is preferable that aliphatic polyester resin foamed particles are crosslinked with organic peroxides.

[0054] The organic peroxide used as a crosslinking agent is preferably one with a half-life temperature of 90°C to 160°C, more preferably one with a half-life of 110°C to 160°C, even more preferably one with a half-life of 110°C to 125°C, and particularly preferably one with a half-life of 114°C to 124°C, although this depends on the type of aliphatic polyester resin used. Specific examples of such organic peroxides include benzoyl peroxide (BPO, half-life temperature: 92°C), t-butyl peroxy-2-ethylhexyl carbonate (TBEC, half-life temperature: 121°C), and 1,1-di(t-butyl peroxy)cyclohexane (TBCH, half-life temperature: 116°C). Using an organic peroxide with a half-life temperature of 90°C or higher has the advantage of tending to produce foamed particles with a desired gel fraction. On the other hand, using organic peroxides with a half-life temperature of 160°C or less has the advantage that unreacted crosslinking agents are less likely to remain in the final product.

[0055] When using a crosslinking agent, the amount used is not particularly limited. The amount of crosslinking agent should be appropriately determined based on the desired degree of crosslinking and closed-cell ratio in the resulting foamed particles. Furthermore, the amount of crosslinking agent used has a positive correlation with the gel fraction of the foamed particles and significantly affects the gel fraction. Therefore, it is also desirable to precisely determine the amount of crosslinking agent used while considering the gel fraction of the resulting foamed particles.

[0056] The gel fraction of the foam particles is preferably 30% to 95% by weight, more preferably 50% to 90% by weight, and even more preferably 60% to 85% by weight, based on 100% by weight of the foam particles. When the gel fraction of the foam particles is (a) 30% by weight or more, based on 100% by weight of the foam particles, it has the advantage of improving productivity by widening the molding temperature range of the foam particles that can provide a high-quality foam molded article when molding the foamed article, and (b) 95% by weight or less, it has the advantage of making it easier to obtain a foamed article with excellent internal fusion at a low molding pressure.

[0057] The following provides a detailed explanation of each step that may be included in this manufacturing method.

[0058] <Method for manufacturing foamed molded products> (molding equipment) The molding apparatus used in this manufacturing method will be described below with reference to Figures 1 and 2.

[0059] (Forming equipment 100) Figure 1 is a schematic diagram showing an example of the general configuration of a molding apparatus 100 used in one embodiment of the present invention. As shown in Figure 1, the molding apparatus 100 includes at least a bunker 1 into which aliphatic polyester resin foam particles are fed, a pressure vessel 2, and a hopper 3 for containing the aliphatic polyester resin foam particles. The arrows indicate the transport direction (movement direction) of the foam particles.

[0060] In the molding apparatus 100, the bunker 1 and the pressure vessel 2 are connected by a first ejector 41 and a first foam particle transport pipe 51, and the pressure vessel 2 and the hopper 3 are connected by a second ejector 42 and a second foam particle transport pipe 52. That is, in the molding apparatus 100, the bunker 1, the first ejector 41, the first foam particle transport pipe 51, the pressure vessel 2, the second ejector 42, the second foam particle transport pipe 52, and the hopper 3 are connected in this order. The molding apparatus 100 is configured such that foam particles introduced into the bunker 1 are supplied into the pressure vessel 2 through the first foam particle transport pipe 51 using the first ejector 41, and then the foam particles, which have internal pressure applied in the pressure vessel 2, are supplied into the hopper 3 through the second foam particle transport pipe 52 using the second ejector 42.

[0061] Although not shown in the diagram, hopper 3 is further provided with a filling machine and a molding machine in that order. Hopper 3 and the filling machine are connected by a fourth foam particle transport pipe. The filling machine and the molding machine are directly connected. The molding machine is equipped with a molding die. The molding die is equipped with a fixed die and a movable die, and is configured such that when the movable die moves toward the fixed die, the molding die is closed and a molding space consisting of the fixed die and the movable die is formed. In other words, the molding die has a molding space consisting of the fixed die and the movable die. The filling machine has the function of filling the molding space formed by the molding die with foam particles. In other words, the molding apparatus 100 is further configured such that the foam particles supplied into hopper 3 pass through the fourth foam particle transport pipe and the filling machine in that order and are supplied into the molding space formed by the molding die. Note that the filling machine equipped in the molding apparatus is not limited in any way to the above configuration as long as it can fill the molding space with foam particles. Furthermore, the molding machine included in the molding apparatus is not limited in any way to the above-described configuration, as long as it can fuse foam particles together to produce a foamed molded body.

[0062] The bunker 1 is not particularly limited in its other configurations, as long as it can accept foam particles. The bunker 1 and the first ejector 41 are directly connected. Foam particles introduced into the bunker 1 are transported to the first ejector 41 through the foam particle outlet (not shown), which is the connection point between the bunker 1 and the first ejector 41. The bunker 1 is positioned vertically above the first ejector 41. Although not shown, the bunker 1 has an inlet for foam particles. Considering the efficiency and ease of introducing foam particles, the cross-sectional area of ​​the inlet of the bunker 1 is designed to be larger than the cross-sectional area of ​​the foam particle outlet of the bunker 1. In other words, the bunker 1 has a tapered shape such that its inner diameter decreases from the inlet to the outlet. In one embodiment of the present invention, the shape of the bunker is not limited to a tapered shape.

[0063] The pressure vessel 2 is used to impart internal pressure to the foamed particles in the internal pressure application process described later. The pressure vessel 2 is not particularly limited in its other configuration, as long as it is configured to withstand a predetermined pressure (for example, 0.05 MPa (absolute pressure) to 0.60 MPa (absolute pressure)) in order to impart internal pressure to the foamed particles. A conventionally known pressure vessel can be used as the pressure vessel 2. The pressure vessel 2 and the second ejector 42 are directly connected. The foamed particles, which have been pressurized in the pressure vessel 2, are transported to the second ejector 42 through the foamed particle outlet (not shown), which is the connection point between the pressure vessel 2 and the second ejector 42. The foamed particle outlet (not shown) of the pressure vessel 2 is equipped with a shutter or the like that allows for opening and closing control. The pressure vessel 2 is positioned vertically above the second ejector 42.

[0064] The hopper 3 is not particularly limited in its configuration as long as it can accommodate the foamed particles. Although not shown in the figures, the hopper 3 is equipped with a foamed particle outlet that supplies the foamed particles contained in the hopper 3 to a fourth foamed particle transport pipe, and is connected to the fourth foamed particle transport pipe via this outlet. The foamed particle outlet may also be equipped with a shutter that allows for control of opening and closing the foamed particle outlet.

[0065] In the molding apparatus 100, the first ejector 41 is directly connected to the bunker 1 and the first foam particle transport pipe 51. Although not shown, a blower is connected to the first ejector 41 either directly or via a short pipe, and the blower is configured and connected to blow air toward the first ejector 41. The air supplied from the blower to the first ejector 41 passes through the inside of the first ejector 41, is discharged from the first ejector 41 to the first foam particle transport pipe 51, and is further sent toward the pressure vessel 2. The first ejector 41 is configured and connected to be able to suck foam particles from the bunker 1 by blowing air from the blower, and to transport the foam particles through the first foam particle transport pipe 51 to the pressure vessel 2 using the blown air as a driving source. In other words, the first ejector 41 in the molding apparatus 100 is a gas ejector that uses air as a driving source. In one embodiment of the present invention, the first ejector is not limited to a gas ejector, but a conventionally known ejector can be used.

[0066] Examples of ejectors include steam ejectors that use steam as a power source, water ejectors that use water or other liquids as a power source, and gas ejectors that use gases other than steam as a power source. From the viewpoint of transport efficiency, a gas ejector that uses air as a power source is preferred as the first ejector.

[0067] In the molding apparatus 100, the first foam particle transport pipe 51 is directly connected to the first ejector 41 and the pressure vessel 2. The first foam particle transport pipe 51 is configured so that air blown from a blower connected to the first ejector 41 can pass through the first foam particle transport pipe 51 toward the pressure vessel 2. The first foam particle transport pipe 51 is also configured so that foam particles can be transported through the first foam particle transport pipe 51 from the first ejector 41 toward the pressure vessel 2 along the airflow within the first foam particle transport pipe 51. The material of the first foam particle transport pipe 51 is hot-dip galvanized steel. In one embodiment of the present invention, the material of the first foam particle transport pipe is not limited to hot-dip galvanized steel. From the viewpoint of corrosion resistance, hot-dip galvanized steel and stainless steel are preferred as the material of the first foam particle transport pipe.

[0068] In the molding apparatus 100, the second ejector 42 is directly connected to the pressure vessel 2 and the second foam particle transport pipe 52. Although not shown, a blower is connected to the second ejector 42 either directly or via a short pipe, and the blower is configured and connected to blow air toward the second ejector 42. The air supplied from the blower to the second ejector 42 passes through the inside of the second ejector 42, is discharged from the second ejector 42 to the second foam particle transport pipe 52, and is further sent toward the hopper 3. The second ejector 42 is configured and connected to be able to suck up foam particles with internal pressure applied from the pressure vessel 2 by blowing air from the blower, and to transport the foam particles through the second foam particle transport pipe 52 to the hopper 3 using the blown air as a driving source. In other words, the second ejector 42 in the molding apparatus 100 is a gas ejector that uses air as a driving source. In one embodiment of the present invention, the second ejector is not limited to a gas ejector, but a conventionally known ejector can be used.

[0069] From the viewpoint of transport efficiency, a gas ejector driven by air is preferred as the second ejector. The first ejector 41 and the second ejector 42 may be the same type of ejector or different types of ejectors.

[0070] In the molding apparatus 100, the second foam particle transport pipe 52 is directly connected to the second ejector 42 and the hopper 3. The second foam particle transport pipe 52 is configured so that air blown from a blower connected to the second ejector 42 can pass through the second foam particle transport pipe 52 toward the hopper 3. The second foam particle transport pipe 52 is also configured so that foam particles can be transported through the second foam particle transport pipe 52 from the second ejector 42 toward the hopper 3 along the airflow within the second foam particle transport pipe 52. The material of the second foam particle transport pipe 52 is hot-dip galvanized steel. In one embodiment of the present invention, the material of the second foam particle transport pipe is not limited to hot-dip galvanized steel. From the viewpoint of corrosion resistance, hot-dip galvanized steel and stainless steel are preferred as the material of the second foam particle transport pipe. The material of the first foam particle transport pipe 51 and the material of the second foam particle transport pipe 52 may be the same or different.

[0071] In Figure 1, the molding apparatus 100 is illustrated as an example in which it has one pressure vessel 2 and one hopper 3. However, the molding apparatus 100 may have two or more pressure vessels 2 and / or two or more hoppers 3. When the molding apparatus 100 has two or more pressure vessels 2, it may have two or more first ejectors 41 and / or two or more first foam particle transport pipes 51 to connect the bunker 1 to each pressure vessel 2. When the molding apparatus 100 has two or more hoppers 3, it may have two or more second ejectors 42 and / or two or more second foam particle transport pipes 52 to connect the pressure vessels 2 to each hopper 3.

[0072] If the molding apparatus 100 has two or more first ejectors 41, the two or more first ejectors 41 may each be of the same type or of different types. If the molding apparatus 100 has two or more second ejectors 42, the two or more second ejectors 42 may each be of the same type or of different types.

[0073] If the molding apparatus 100 has two or more first foam particle transport pipes 51, the materials of the two or more first foam particle transport pipes 51 may be the same or different. If the molding apparatus 100 has two or more second foam particle transport pipes 52, the materials of the two or more second foam particle transport pipes 52 may be the same or different.

[0074] In the molding apparatus 100, the bunker 1 and the pressure vessel 2 are directly connected via a first ejector 41 and a first foam particle transport pipe 51, and the pressure vessel 2 and the hopper 3 are directly connected via a second ejector 42 and a second foam particle transport pipe 52. However, in one embodiment of the present invention, in the molding apparatus 100, one or more additional components, such as silos, may be installed between the bunker 1 and the pressure vessel 2, and / or between the pressure vessel 2 and the hopper 3.

[0075] In the molding apparatus 100, if, for example, an additional silo is installed between the bunker 1 and the pressure vessel 2, it is preferable that the transport of foamed particles between the bunker 1 and the silo is carried out by using a first ejector 41 through a first foamed particle transport pipe 51, and it is also preferable that the transport of foamed particles between the silo and the pressure vessel 2 is carried out by using a first ejector 41 through a first foamed particle transport pipe 51. That is, in addition to providing a first ejector 41 between the bunker 1 and the silo, it is preferable to further provide a first ejector 41 between the silo and the pressure vessel 2. The first ejector 41 further provided between the silo and the pressure vessel 2 may be installed above the silo in the vertical direction and directly connected to the silo.

[0076] In the molding apparatus 100, if, for example, an additional silo is installed between the pressure vessel 2 and the hopper 3, it is preferable that the transport of foamed particles between the pressure vessel 2 and the silo is carried out by transporting them through a second foamed particle transport pipe 52 using a second ejector 42, and it is also preferable that the transport of foamed particles between the silo and the hopper 3 is carried out by transporting them through a second foamed particle transport pipe 52 using a second ejector 42. That is, in addition to providing a second ejector 42 between the pressure vessel 2 and the silo, it is preferable to further provide a second ejector 42 between the silo and the hopper 3. The second ejector 42 further provided between the silo and the hopper 3 may be installed above the silo in the vertical direction and directly connected to the silo.

[0077] (Forming equipment 200) Figure 2 is a schematic diagram showing an example of the general configuration of a molding apparatus 200 used in one embodiment of the present invention. In the molding apparatus 200, components that have the same function as components in the molding apparatus 100 are denoted by the same reference numerals and their descriptions are omitted. As shown in Figure 2, the difference between the molding apparatus 200 and the molding apparatus 100 is that the molding apparatus 100 is equipped with a pressure vessel 2, whereas the molding apparatus 200 is not equipped with a pressure vessel. That is, the molding apparatus 200 has at least a bunker 1 into which aliphatic polyester resin foam particles are fed and a hopper 3 that contains the aliphatic polyester resin foam particles, but it does not have a pressure vessel. The arrows indicate the transport direction (movement direction) of the foam particles.

[0078] In the molding apparatus 200, the bunker 1 and the hopper 3 are connected by a third ejector 43 and a third foam particle transport pipe 53. The molding apparatus 200 is configured so that foam particles introduced into the bunker 1 are supplied into the hopper 3 via the third foam particle transport pipe 53 using the third ejector 43.

[0079] In the molding apparatus 200, the bunker 1 and the third ejector 43 are directly connected. In the molding apparatus 200, foam particles introduced into the bunker 1 are transported to the third ejector 43 through the foam particle outlet (not shown), which is the connection point between the bunker 1 and the third ejector 43. The bunker 1 is positioned vertically above the third ejector 43. In the molding apparatus 200, although not shown, the bunker 1 also has an inlet for foam particles, and the bunker 1 has a tapered shape such that its inner diameter decreases from the inlet to the outlet.

[0080] In the molding apparatus 200, the third ejector 43 is directly connected to the bunker 1 and the third foam particle transport pipe 53. Although not shown, a blower is connected to the third ejector 43 either directly or via a short pipe, and the blower is configured and connected to blow air toward the third ejector 43. The air supplied from the blower to the third ejector 43 passes through the inside of the third ejector 43, is discharged from the third ejector 43 to the third foam particle transport pipe 53, and is further sent toward the hopper 3. The third ejector 43 is configured and connected to be able to suck foam particles from the bunker 1 by blowing air from the blower, and to transport the foam particles through the third foam particle transport pipe 53 to the hopper 3 using the blown air as a driving source. In other words, the third ejector 43 in the molding apparatus 200 is a gas ejector that uses air as a driving source. In one embodiment of the present invention, the third ejector is not limited to a gas ejector, but a conventionally known ejector can be used.

[0081] From the viewpoint of transport efficiency, a gas ejector that uses air as a driving source is preferred as the third ejector.

[0082] In the molding apparatus 200, the third foam particle transport pipe 53 is directly connected to the third ejector 43 and the hopper 3. The third foam particle transport pipe 53 is configured so that air blown from a blower connected to the third ejector 43 can pass through the third foam particle transport pipe 53 toward the hopper 3. The third foam particle transport pipe 53 is also configured so that foam particles can be transported through the third foam particle transport pipe 53 from the third ejector 43 toward the hopper 3 along the airflow within the pipe. The material of the third foam particle transport pipe 53 is hot-dip galvanized steel. In one embodiment of the present invention, the material of the third foam particle transport pipe is not limited to hot-dip galvanized steel. From the viewpoint of corrosion resistance, hot-dip galvanized steel and stainless steel are preferred as the material of the third foam particle transport pipe.

[0083] Similar to the molding apparatus 100, the molding apparatus 200 also has a filling machine and a molding machine in the hopper 3, although these are not shown in Figure 2. The filling machine and molding machine are the same as those described for the molding apparatus 100, so we will refer to that description and omit further explanation here. In other words, the molding apparatus 200 is further configured so that the foamed particles supplied into the hopper 3 pass through the fourth foamed particle transport pipe and the filling machine in that order and are supplied into the molding space formed by the molding die.

[0084] In the molding apparatus 200, the bunker 1 and the hopper 3 are directly connected via a third ejector 43 and a third foam particle transport pipe 53. However, in one embodiment of the present invention, in the molding apparatus 200, one or more additional components (excluding pressure vessels), such as silos, may be installed between the bunker 1 and the hopper 3.

[0085] In the molding apparatus 200, if, for example, an additional silo is installed between the bunker 1 and the hopper 3, it is preferable that the transport of foamed particles between the bunker 1 and the silo is carried out by transporting them through a third foamed particle transport pipe 53 using a third ejector 43, and it is also preferable that the transport of foamed particles between the silo and the hopper 3 is carried out by transporting them through a third foamed particle transport pipe 53 using a third ejector 43. That is, in addition to providing a third ejector 43 between the bunker 1 and the silo, it is preferable to provide a third ejector 43 between the silo and the hopper 3 as well. The third ejector 43 provided between the silo and the hopper 3 may be installed above the silo in the vertical direction and directly connected to the silo.

[0086] (Transportation process (A1)) The transport process (A1) transports aliphatic polyester resin foam particles from bunker 1 to pressure vessel 2 using a first ejector 41 through a first foam particle transport pipe 51. In other words, in the transport process (A1), foam particles are moved from bunker 1 to pressure vessel 2 through the first foam particle transport pipe 51, and the driving force for this is provided by the first ejector 41. To explain in more detail, foam particles introduced into bunker 1 through the inlet of bunker 1 approach the foam particle outlet (not shown) of bunker 1 due to the weight of the foam particles themselves, and are then transported through the foam particle outlet into the interior of the first ejector 41 by suction from the first ejector 41. The foam particles transported into the first ejector 41 are transported to the pressure vessel 2 through the first foam particle transport pipe 51, following the flow of air blown from the blower to the first ejector 41 and discharged from the first ejector 41, in other words, using the air discharged from the first ejector 41 as the driving force.

[0087] In this specification, "transport ambient temperature" refers to the ambient temperature (also known as ambient temperature or space temperature) when carrying out the transport process. The transport ambient temperature in transport process (A1) is not particularly limited, but is preferably 5°C to 60°C, more preferably 10°C to 55°C, even more preferably 15°C to 55°C, and particularly preferably 20°C to 50°C. This configuration has the advantage of being able to obtain a foamed molded product in which deformation is prevented or reduced. In this specification, the transport ambient temperature in transport process (A1), transport process (A2), and transport process (B) is the temperature determined by measuring with a thermometer installed in the transport pipe. The transport ambient temperature can also be adjusted, for example, by heating the air introduced from the blower to each of the first, second, or third ejectors using a steam heat exchanger and controlling the temperature of the heat exchanger. Alternatively, the transport atmosphere temperature can be adjusted by heating each of the first, second, or third foam particle transport tubes from the outside and controlling the heating temperature.

[0088] (Internal pressure application process) The internal pressure application step is a step in which internal pressure is applied to the foamed particles inside the pressure vessel 2 by increasing the pressure inside the pressure vessel 2 containing the foamed particles.

[0089] In the internal pressure application process, the method for increasing the pressure inside the pressure vessel 2 is not particularly limited, but one example is supplying an inorganic gas into the pressure vessel 2. When an inorganic gas is supplied into the pressure vessel 2, the inorganic gas can be impregnated into the foamed particles inside the pressure vessel 2, thereby applying internal pressure to the foamed particles.

[0090] In the internal pressure application process, it is necessary to increase the pressure inside the pressure vessel 2, so the pressure vessel 2 is sealed. For example, the foam particle outlet (not shown) of the pressure vessel 2 is closed.

[0091] The inorganic gas is not particularly limited, but examples include air, nitrogen, oxygen, carbon dioxide, helium, neon, and argon. One of these inorganic gases may be used alone, or two or more may be used in mixture. When two or more inorganic gases are used in mixture, the mixing ratio may be adjusted as appropriate depending on the purpose. Among these inorganic gases, air and / or carbon dioxide are preferred, and air is more preferred, because they result in good productivity of the foamed molded product and reduce costs.

[0092] The internal pressure of the foamed particles after internal pressure is applied is more preferably greater than 0.10 MPa (absolute pressure) (in other words, greater than atmospheric pressure) and 0.22 MPa (absolute pressure) or less, preferably between 0.12 MPa (absolute pressure) and 0.19 MPa (absolute pressure), even more preferably between 0.13 MPa (absolute pressure) and 0.18 MPa (absolute pressure), even more preferably between 0.14 MPa (absolute pressure) and 0.17 MPa (absolute pressure), and particularly preferably between 0.15 MPa (absolute pressure) and 0.17 MPa (absolute pressure). By setting the internal pressure of the foamed particles within the above range, a foamed molded article with excellent surface properties and internal fusion rate can be provided. The internal pressure of the foamed particles is the temperature determined by the method described in detail in the examples below.

[0093] In the internal pressure application step, the temperature inside the pressure vessel 2 may be adjusted to a predetermined range. The temperature inside the pressure vessel 2 in the internal pressure application step is not particularly limited, but 10°C to 90°C is preferred, and 40°C to 90°C is more preferred, as this results in good productivity of the foamed molded product.

[0094] (Pressure release process) The pressure release process is a process of releasing the pressure inside the pressure vessel 2 while the foamed particles, which have been subjected to internal pressure, are contained within the pressure vessel 2. For example, when an inorganic gas is supplied into the pressure vessel 2 during the internal pressure application process, the pressure inside the pressure vessel 2 can be released by opening a lid (for example, the lid of the exhaust valve) provided on the pressure vessel 2 to discharge the gas inside the pressure vessel 2.

[0095] When internal pressure is applied to the foamed particles inside a pressure vessel by increasing the pressure inside the vessel, the pressure inside the vessel can exceed atmospheric pressure. Therefore, when releasing the pressure inside the pressure vessel after it has been pressurized, the pressure difference between the pressure inside the vessel and atmospheric pressure can be used to simultaneously release the pressure inside the vessel and pump the foamed particles inside the vessel to the next component (e.g., a foamed particle transport pipe). Typically, when using thermoplastic resin foamed particles such as polyolefin resin foamed particles and polystyrene resin foamed particles, production efficiency is improved, so thermoplastic resin foamed particles that have been pressurized inside the pressure vessel are pumped to the next component (e.g., a foamed particle transport pipe) when the pressure inside the vessel is released. During their intensive research, the inventors independently obtained the following novel finding: When using aliphatic polyester resin foam particles, although production efficiency is lower, by applying internal pressure to the aliphatic polyester resin foam particles in a pressure vessel and then not pumping the pressure-applied aliphatic polyester resin foam particles to the next component (e.g., a foam particle transport pipe) when the pressure in the pressure vessel is released, it is possible to obtain an aliphatic polyester resin foam molded article in which deformation is prevented or reduced. Therefore, in this manufacturing method, when releasing the pressure in the pressure vessel 2 after the internal pressure application step, the pressure-applied foam particles are not pumped into the subsequent second foam particle transport pipe 52, but rather the pressure-applied foam particles remain in the pressure vessel 2 when the pressure is released. In other words, in this manufacturing method, even after the pressure release step, the same amount or approximately the same amount of foam particles as after the internal pressure application step remain in the pressure vessel 2. Therefore, even during the pressure release process, the foam particle outlet (not shown) of the pressure vessel 2 remains closed.

[0096] (Transportation process (A2)) The transport process (A2) transports aliphatic polyester resin foam particles, which have internal pressure applied to them, from the pressure vessel 2 to the hopper 3, using the second ejector 42 and passing through the second foam particle transport pipe 52. In other words, in the transport process (A2), foam particles, which have internal pressure applied to them, are moved from the pressure vessel 2 to the hopper 3, passing through the second foam particle transport pipe 52, and the driving force for this is provided by the second ejector 42. To explain in more detail: After the pressure release process, the foam particle outlet (not shown) of the pressure vessel 2 is opened. As a result, the foam particles, which have internal pressure applied to them inside the pressure vessel 2, are transported by suction from the second ejector 42, passing through the foam particle outlet (not shown) of the pressure vessel 2 and into the interior of the second ejector 42. The foam particles, which have been pressurized and transported into the second ejector 42, are transported to the hopper 3 through the second foam particle transport pipe 52, following the airflow from the blower to the second ejector 42 and the air discharged from the second ejector 42, in other words, using the air discharged from the second ejector 42 as the driving force.

[0097] The transport atmosphere temperature in transport process (A2) is not particularly limited, but is preferably 5°C to 60°C, more preferably 10°C to 55°C, even more preferably 15°C to 55°C, and particularly preferably 20°C to 50°C. This configuration has the advantage of being able to obtain a foamed molded product in which deformation is prevented or reduced. The transport atmosphere temperature in transport process (A2) may be the same as or different from the transport atmosphere temperature in transport process (A1).

[0098] (Transportation process (B)) In transport process (B), aliphatic polyester resin foam particles are transported from bunker 1 to hopper 3 using a third ejector 43 through a third foam particle transport pipe 53. In other words, in transport process (B), foam particles are moved from bunker 1 to hopper 3 through the third foam particle transport pipe 53, and the driving force is provided by the third ejector 43. The foam particles transported in transport process (B) are foam particles that have no internal pressure applied to them. To explain in more detail, foam particles introduced into bunker 1 through the inlet of bunker 1 approach the foam particle outlet (not shown) of bunker 1 due to the weight of the foam particles themselves, and are transported through the foam particle outlet into the interior of the third ejector 43 by suction from the third ejector 43. The foam particles transported into the third ejector 43 are transported to the hopper 3 through the third foam particle transport pipe 53, following the airflow from the blower to the third ejector 43 and then discharged from the third ejector 43. In other words, the air discharged from the third ejector 43 acts as the driving force.

[0099] The transport atmosphere temperature in transport process (B) is not particularly limited, but is preferably 5°C to 60°C, more preferably 10°C to 55°C, even more preferably 15°C to 55°C, and particularly preferably 20°C to 50°C. This configuration has the advantage of being able to obtain a foamed molded article in which deformation is prevented or reduced.

[0100] (Other processes) This manufacturing method may include other steps in addition to the transport step (A1), internal pressure application step, pressure release step, and transport step (A2) described above, or in addition to the transport step (B). For example, in addition to the steps described above, this manufacturing method may further include (i) a filling step in which foamed particles contained in the hopper 3 are filled into the molding space of the molding die via foamed particle transport piping and a filling machine, and (ii) a foam molding step in which the foamed particles filled into the molding space of the molding die by the filling step are heated, for example with steam, to fuse the foamed particles together and form the mold. The conditions for carrying out these other steps can be determined as appropriate.

[0101] In the filling process, the mold does not need to be completely closed, and a small gap (also called cracking) may be formed between the fixed mold and the movable mold. The amount of cracking (distance, mm) is not particularly limited.

[0102] If the mold cracks during the filling process, the movable mold is driven toward the fixed mold during the foam molding process to ensure that the mold is completely closed.

[0103] The method for fusing the foam particles in the foam molding process is not particularly limited. For example, the foam particles can be fused by preheating the mold with steam, then heating the mold in one direction and in the other direction with steam, and finally heating the mold on both sides with steam. The steam pressure during one-way heating, reverse one-way heating, and double-sided heating is not particularly limited.

[0104] [3. Foamed molded product] According to this manufacturing method, a foamed molded article made from an aliphatic polyester resin, in other words, an aliphatic polyester resin foamed molded article, can be obtained. The aliphatic polyester resin foamed molded article obtained by this manufacturing method can also be said to be one embodiment of the present invention. The aliphatic polyester resin foamed molded article according to one embodiment of the present invention is manufactured by this manufacturing method and may be a foamed molded article that does not deform, or if it does deform, the amount of deformation is smaller than that of conventional foamed molded articles. The amount of deformation of the foamed molded article can be evaluated by the method described in the examples below.

[0105] Furthermore, in a preferred embodiment of the present invention, the aliphatic polyester resin foam molded article according to one embodiment of the present invention also has the advantage of having excellent surface properties as evaluated by the method described in the examples below.

[0106] This foamed molded product can be suitably used for, for example, packaging cushioning materials (e.g., cushioning materials for packaging home appliances such as refrigerators, freezers, air conditioner bodies and their outdoor units, washing machines, air purifiers, humidifiers, rice cookers, microwave ovens, ovens, toasters, electric fans, and battery units; cushioning materials for packaging automotive parts such as transmissions, roofs, hoods, doors, batteries, and engines); logistics materials (e.g., agricultural product boxes, fish boxes, etc.); insulation materials; civil engineering and construction components; and automotive components (e.g., toolboxes, risers, core materials for seat cushions, bumper core materials, tibial pads, door trims, etc.). [Examples]

[0107] The present invention will be specifically described below with reference to examples, but the technical scope of the present invention is not limited by these examples.

[0108] 〔material〕 The substances used in the examples and comparative examples are shown below.

[0109] (Aliphatic polyester resin) The monomer is P3HA:P3HB3HH (monomer ratio: 3HB / 3HH = 95 / 5 (mol% / mol%), melting point 145°C), and was prepared in accordance with the method described in paragraphs

[0064] to

[0125] of International Publication WO2009 / 145164.

[0110] (Crystallizing agent) Pentaerythritol (Neurizer P: Mitsubishi Chemical Corporation) (Lubricant) Behenamide (manufactured by Tokyo Chemical Industry Co., Ltd.) Erucic acid amide (manufactured by Tokyo Chemical Industry Co., Ltd.) (Bubble regulator) Talc (Talc powder PKS manufactured by Hayashi Chemical Co., Ltd.) (Crosslinking agent (organic peroxide)) 1,1-di(t-butylperoxy)cyclohexane (TBCH: manufactured by NOF Corporation) (Foaming agent) Carbon dioxide (manufactured by Air Water Inc.) (Dispersant) Tricalcium phosphate (manufactured by Taihei Chemical Industry Co., Ltd., specific gravity 3.1, pH 6) (Dispersing agent) Sodium alkanesulfonate (Latemul PS, manufactured by Kao Corporation) (Cleaning agent) Sodium hexametaphosphate (manufactured by Taihei Chemical Industry Co., Ltd.).

[0111] [Measurement and evaluation methods] The measurement and evaluation methods used in the examples and comparative examples are described below.

[0112] (Measurement of gel fraction of foamed particles) The method for measuring the gel fraction of foamed particles was as follows (1) to (5): (1) 1 g of foamed particles and 100 ml of chloroform were placed in a 150 ml flask; (2) The mixture in the flask was heated under atmospheric pressure at 62°C for 8 hours under reflux; (3) The resulting heat-treated material was filtered using a suction filtration apparatus equipped with a 100-mesh wire mesh; (4) The filtered material on the wire mesh was dried in an oven at 80°C under vacuum conditions for 8 hours, and the weight Wg (g) of the dried material was measured; (5) The gel fraction was calculated using the following formula: Gel fraction (weight %) = Wg / 1 × 100.

[0113] (Measurement of apparent density of foam particles) The method for measuring the density of foaming particles was as follows (1) to (3): (1) A graduated cylinder containing ethanol was prepared, and foaming particles weighing Wd (g) were submerged in the ethanol; (2) The volume of foaming particles was read from the rise in the ethanol level (submersion method) and measured as Vd (cm 3 (3) The apparent density of the foamed particles was calculated using the following formula (1). Apparent density of foamed particles (g / cm³) 3 ) = Wd / Vd···(1).

[0114] (Measurement of internal pressure of foamed particles) The method for measuring the internal pressure of the foamed particles was as follows (1) to (5): (1) The weight W1 (g) of the foamed particles after applying internal pressure was measured; (2) The foamed particles were heated at 150°C for 30 minutes to dissipate the inorganic gas inside the foamed particles; (3) The weight W2 (g) of the foamed particles from which the inorganic gas had been dissipated was measured again; (4) The weight of the inorganic gas (ΔW) was calculated from the weight difference (W1-W2) of the foamed particles before and after dissipation of the inorganic gas; (5) The internal pressure P (MPa (absolute pressure)) of the foamed particles was calculated using the ideal gas law (specifically, the following equation): Internal pressure P (MPa (absolute pressure)) of foamed particles = (1 + (ΔW / 28.8) × 0.082 × (273 + T) × (ρ × 1000 / W²)) / 9.87 In the above formula, T is the temperature (room temperature) at which the weight of the foamed particles after internal pressure was measured, and ρ is the apparent density (g / cc) of the foamed particles (foamed particles with weight W1) after internal pressure was applied.

[0115] Here, the method for measuring the apparent density of foamed particles (foamed particles after internal pressure is applied) was as follows: (1) A graduated cylinder containing ethanol was prepared, and foamed particles weighing Wd (g) were submerged in the ethanol; (2) The volume of the foamed particles, read from the rise in the ethanol level (submersion method), was defined as Vd (cc); (3) The apparent density of the foamed particles was calculated using the following formula; The apparent density of foamed particles (g / cc) = Wd / Vd.

[0116] (Measurement of the open-cell ratio of foamed particles) The method for measuring the open-cell ratio of foamed particles was as follows: (1) Using an air-comparison hydrometer [Tokyo Science Co., Ltd., Model 1000], the true volume Vc (cm³) of the foamed particles was measured in accordance with the method described in Procedure C of ASTM D2856-87. 3 (2) The volume of the foaming particles after measuring Vc was then submerged in a graduated cylinder containing ethanol, and the apparent volume of the foaming particles Va (cm³) was determined from the rise in the water level in the graduated cylinder (submersion method). 3 (3) The percentage of open bubbles in the foamed particles was calculated using the following formula: The percentage of open cells in foamed particles (%) = (Va - Vc) × 100 / Va.

[0117] (Evaluation of surface properties of foamed molded products) The surface of the foamed molded product was visually inspected and its surface quality was evaluated based on the following criteria. A higher number indicates fewer sink marks on the surface of the foamed molded product; in other words, superior surface quality. 4 (Particularly good): Almost no sink marks are visible on the surface of the foamed molded product. 3 (Good): Slight sink marks are visible on the surface of the foamed molded product. 2 (Pass): Slight sink marks are visible on the surface of the foamed molded product. 1 (Defective): Significant sink marks are visible on the surface of the foamed molded product.

[0118] (Deformation of foamed molded body) Figure 3 shows the shape of the foamed molded body 300 obtained in this embodiment. The foamed molded body 300 has a box-like shape with a partition 302 (external dimensions: 150 mm long x 300 mm wide x 130 mm high, thickness of vertical wall 301: 20 mm, thickness of partition 302: 120 mm, thickness of bottom 303: 50 mm).

[0119] The foamed molded body was placed on a horizontal surface with its recess facing the horizontal plane (i.e., with the bottom 303 of the foamed molded body facing upwards). A taper gauge was inserted into the gap between the foamed molded body and the horizontal plane until the taper gauge contacted both the foamed molded body and the horizontal plane, and the size of the gap was measured. This measured gap size was defined as the deformation amount of the foamed molded body. A smaller deformation amount indicates a foamed molded body with less deformation.

[0120] [Manufacturing Example 1] <Production of foamed particles> (Aliphatic polyester resin foam particles) (1) Preparation of aliphatic polyester resin particles (resin particle manufacturing process) 100 parts by weight of P3HA, 1.0 part by weight of pentaerythritol, 0.50 parts by weight of behenamide, 0.50 parts by weight of erucamide, and 0.10 parts by weight of talc were weighed and dry blended to prepare an aliphatic polyester resin composition. The prepared aliphatic polyester resin composition was supplied to a twin-screw extruder (TEM-26SX manufactured by Toshiba Machine Co., Ltd.) and melt-kneaded at a cylinder setting temperature of 130°C to 160°C (melt-kneading process). The melt-kneaded aliphatic polyester resin composition at 179°C was discharged from the nozzle of a die attached to the tip of the extruder. The discharged aliphatic polyester resin composition was water-cooled with 50°C water and then cut to obtain cylindrical aliphatic polyester resin particles with a length / diameter of 2.0 (resin particle molding process).

[0121] (2) Preparation of aliphatic polyester resin foam particles (foaming process) 100 parts by weight (2.5 kg) of aliphatic polyester resin particles obtained in the resin particle manufacturing process, 200 parts by weight of pure water as an aqueous dispersion medium, 2.0 parts by weight of 1,1-di(t-butylperoxy)cyclohexane (TBCH) as a crosslinking agent, 1.0 part by weight of tricalcium phosphate as a dispersant, and 0.05 parts by weight of sodium alkanesulfonate as a dispersion aid were supplied to a pressure vessel with a volume of 10 L equipped with a stirring blade, and the stirring blade was rotated at 260 rpm to stir the raw materials inside the pressure vessel. The contents (dispersion) inside the pressure vessel were continued to be stirred until the release of the dispersion was complete.

[0122] After introducing nitrogen into the pressure vessel, the vessel was evacuated to remove oxygen. Furthermore, carbon dioxide was supplied as a foaming agent to the pressure vessel to prepare a dispersion (dispersion step). The temperature inside the pressure vessel was then raised to the foaming temperature of 129.0°C. Further, carbon dioxide was supplied to the pressure vessel to raise the pressure to the foaming pressure of 3.3 MPa (gauge pressure) (heating-pressure raising step). Next, the temperature and pressure inside the pressure vessel were maintained at approximately the foaming temperature and pressure, respectively, for 30 minutes (holding step). After the holding step, the valve at the bottom of the pressure vessel was opened, and the dispersion was released into atmospheric pressure through a 3.6 mm diameter open orifice to obtain aliphatic polyester resin foam particles (release step).

[0123] The obtained foamed particles were washed with an aqueous solution of sodium hexametaphosphate and water to remove any dispersants adhering to their surface, and then dried at 75°C. The apparent density of the obtained foamed particles was 0.076 g / cm³. 3 The foam particle ratio was 16x, and the gel fraction was 67% by weight.

[0124] <Molding of foamed molded products> In Examples 1-3, the molding apparatus 100 shown in Figure 1 was used, while in Examples 4-6, the molding apparatus 200 shown in Figure 2 was used. The molding apparatus 100 had a bunker 1 into which foam particles were introduced, a pressure vessel 2, and a hopper 3 for containing the foam particles. The bunker 1 and the pressure vessel 2 were connected by a first ejector 41 and a first foam particle transport pipe 51, and the pressure vessel 2 and the hopper 3 were connected by a second ejector 42 and a second foam particle transport pipe 52. The molding apparatus 200 had a bunker 1 into which foam particles were introduced and a hopper 3 for containing the foam particles. The bunker 1 and the hopper 3 were connected by a third ejector 43 and a third foam particle transport pipe 53. The same ejector was used for the first ejector 41, the second ejector 42, and the third ejector 43. The first foamed particle transport pipe 51, the second foamed particle transport pipe 52, and the third foamed particle transport pipe 53 were all made of the same material, hot-dip galvanized steel.

[0125] Although not shown in Figures 1 and 2, in molding apparatuses 100 and 200, a filling machine and a molding machine (DABO DPM-1300) were provided in that order following the hopper 3. The molding machine consisted of a fixed mold and a movable mold, and was equipped with a molding die capable of molding six foamed molded bodies 300 (external dimensions: 150 mm long x 300 mm wide x 130 mm high, with a vertical wall 301 thickness of 20 mm, a partition 302 thickness of 120 mm, and a bottom 303 thickness of 50 mm) as shown in Figure 3. The filling machine was a device for filling the molding die with foamed particles.

[0126] In Comparative Examples 1-6 and Reference Examples 1-2, the molding apparatus used included a bunker into which foam particles were introduced, a pressure vessel, and a hopper for containing the foam particles. The bunker and the pressure vessel were connected by an ejector or blower and a foam particle transport pipe, and the pressure vessel and the hopper were connected by an ejector or blower and a foam particle transport pipe. Furthermore, in the molding apparatus, the filling machine described above was provided following the hopper, and the molding machine described above was provided following the filling machine.

[0127] In Comparative Examples 7 and 8, the molding apparatus used had a bunker into which foam particles were introduced and a hopper for containing the foam particles, and the bunker and hopper were connected by an ejector or blower and a foam particle transport pipe. Furthermore, in the molding apparatus, the filling machine described above was provided following the hopper, and the molding machine described above was provided following the filling machine.

[0128] The ejectors used in Comparative Examples 1-4 were the same as those used in the molding apparatus used in the Examples. The blowers used in Comparative Examples 1-8 and Reference Examples 1-2 were blowers manufactured by Tofusuki Co., Ltd.

[0129] [Example 1] The foamed particles obtained in Manufacturing Example 1 were supplied to Bunker 1. From Bunker 1 to Pressure Vessel 2, the foamed particles were transported through the first foamed particle transport pipe 51 using the first ejector 41 under a temperature atmosphere of 20°C (transportation process (A1)). Next, the internal pressure inside Pressure Vessel 2 was increased using air to impart an internal pressure of 0.16 MPa (absolute pressure) to the foamed particles supplied to Pressure Vessel 2 (internal pressure application process). Subsequently, with the foamed particles containing the applied internal pressure still inside, the pressure inside Pressure Vessel 2 was released to atmospheric pressure (pressure release process). After that, the foamed particles with the applied internal pressure inside Pressure Vessel 2 were transported from Pressure Vessel 2 to Hopper 3 under a temperature atmosphere of 20°C using the second ejector 42 through the second foamed particle transport pipe 52 (transportation process (A2)). Table 1 shows the type of transport process performed in Example 1, the transport means used during the transport process, the ambient temperature during the transport process (transport ambient temperature), and the internal pressure applied to the foamed particles during the internal pressure application process.

[0130] Furthermore, the open-cell ratio of the foamed particles in hopper 3 was measured using the method described above. The results are shown in Table 1.

[0131] Next, the shutter of hopper 3 was opened, and the foamed particles inside hopper 3 were filled into the molding space of the molding die, which was set to a cracking amount of 6 mm (filling process).

[0132] After filling was complete, the movable mold was driven toward the fixed mold, and the molding die was completely closed. Then, the molding die was preheated with steam, and further heated with steam in one direction and in the other, and in addition, heated with steam on both sides. Through these operations, the filled foam particles were fused together to obtain a foamed molded body (foaming molding process). Here, the steam pressure during one-way heating and reverse one-way heating (steam pressure A) was set to 0.03 MPa (gauge pressure), and the steam pressure during double-sided heating (steam pressure B) was set to 0.14 MPa (gauge pressure). The obtained foamed molded body was removed from the mold and dried at 75°C. The deformation amount of the foamed molded body after drying was measured and the surface properties were evaluated. The results are shown in Table 1.

[0133] [Examples 2-3] Except for changing the transport atmosphere temperature in transport processes (A1) and transport process (A2) as shown in Table 1, the transport process (A1), internal pressure application process, pressure release process, and transport process (A2) were carried out in the same manner as in Example 1, and the foamed particles with internal pressure applied were transported to hopper 3. The open-cell ratio of the foamed particles in hopper 3 was measured using the method described above. The results are shown in Table 1. Subsequently, the filling process and foam molding process were carried out in the same manner as in Example 1 to obtain a foamed molded body. The obtained foamed molded body was removed from the mold and dried at 75°C. The deformation amount of the foamed molded body after drying was measured and the surface properties were evaluated. The results are shown in Table 1.

[0134] [Example 4] The foamed particles obtained in Manufacturing Example 1 were supplied to Bunker 1. From Bunker 1 to Hopper 3, the foamed particles were transported through a third foamed particle transport pipe 53 using a third ejector 43 under a temperature atmosphere of 20°C (transportation process (B)). In other words, in Example 4, internal pressure was not applied to the foamed particles using air. Table 1 shows the type of transport process performed in Example 4, the transport means used during the transport process, and the ambient temperature during the transport process (transport ambient temperature), respectively.

[0135] Furthermore, the open-cell ratio of the foamed particles in hopper 3 was measured using the method described above. The results are shown in Table 1.

[0136] Next, the shutter of hopper 3 was opened, and the foamed particles inside hopper 3 were filled into the molding space of the molding die, which was set to a cracking amount of 12 mm (filling process).

[0137] After filling was complete, a foam molding process was carried out in the same manner as in Example 1 to obtain a foamed molded body. The obtained foamed molded body was removed from the mold and dried at 75°C. The deformation amount of the dried foamed molded body was measured and the surface properties were evaluated. The results are shown in Table 1.

[0138] [Examples 5-6] Except for changing the transport atmosphere temperature in transport process (B) as shown in Table 1, transport process (B) was carried out in the same manner as in Example 4, and the foamed particles were transported to hopper 3. That is, in Examples 5 and 6, internal pressure using air was not applied to the foamed particles. The open-cell ratio of the foamed particles in hopper 3 was measured using the method described above. The results are shown in Table 1. Next, the filling process was carried out in the same manner as in Example 4. Subsequently, the foam molding process was carried out in the same manner as in Example 1 to obtain a foamed molded body. The obtained foamed molded body was removed from the mold and dried at 75°C. The deformation amount of the foamed molded body after drying was measured and the surface properties were evaluated. The results are shown in Table 1.

[0139] [Comparative Examples 1-6] Except for changing the transport atmosphere temperature and transport means in transport processes (A1) and (A2) as shown in Table 2, the transport process (A1), internal pressure application process, pressure release process, and transport process (A2) were carried out in the same manner as in Example 1, and the foamed particles with internal pressure applied were transported to hopper 3. The open-cell ratio of the foamed particles in hopper 3 was measured using the method described above. The results are shown in Table 1. Subsequently, the filling process and foam molding process were carried out in the same manner as in Example 1 to obtain a foamed molded body. The obtained foamed molded body was removed from the mold and dried at 75°C. The deformation amount of the foamed molded body after drying was measured and the surface properties were evaluated. The results are shown in Table 2.

[0140] [Comparative Examples 7-8] Except for changing the transport atmosphere temperature and transport method in transport process (B) as shown in Table 2, transport process (B) was carried out in the same manner as in Example 4, and the foamed particles were transported to hopper 3. That is, in Examples 7 and 8, internal pressure using air was not applied to the foamed particles. The open-cell ratio of the foamed particles in hopper 3 was measured using the method described above. The results are shown in Table 1. Next, the filling process was carried out in the same manner as in Example 4. Subsequently, the foam molding process was carried out in the same manner as in Example 1 to obtain a foamed molded body. The obtained foamed molded body was removed from the mold and dried at 75°C. The deformation amount of the foamed molded body after drying was measured and the surface properties were evaluated. The results are shown in Table 2.

[0141] [Reference example 1] Polypropylene resin foam particles (indicated as "PP" in Table 2) (Eperan-PP manufactured by Kaneka Corporation (30x foaming ratio)) were used instead of aliphatic polyester resin foam particles. The transport atmosphere temperature and transport means in the transport process (A1) and transport process (A2), as well as the internal pressure applied to the foam particles in the internal pressure application process, were changed as shown in Table 2. Except for these changes, the transport process (A1), internal pressure application process, pressure release process, and transport process (A2) were carried out in the same manner as in Example 1, and the foam particles to which internal pressure had been applied were transported to hopper 3. The open-cell ratio of the foam particles in hopper 3 was measured using the method described above. The results are shown in Table 1. Next, the filling process was carried out in the same manner as in Example 1. Subsequently, the steam pressure (steam pressure A) during one-sided heating and reverse one-sided heating was changed to 0.15 MPa (gauge pressure), and the steam pressure (steam pressure B) during double-sided heating was changed to 0.30 MPa (gauge pressure). Except for these changes, the foam molding process was carried out in the same manner as in Example 1 to obtain a foam molded body. The resulting foamed molded body was removed from the mold and dried at 75°C. The deformation of the dried foamed molded body was measured, and its surface properties were evaluated. The results are shown in Table 2.

[0142] [Reference example 2] Polyethylene resin foam particles (indicated as "PE" in Table 2) (Eperan manufactured by Kaneka Corporation (foaming ratio 38 times)) were used instead of aliphatic polyester resin foam particles, and the transport atmosphere temperature and transport means in transport process (A1) and transport process (A2), as well as the internal pressure applied to the foam particles in the internal pressure application process, were changed as shown in Table 2. Except for these changes, the transport process (A1), internal pressure application process, pressure release process, and transport process (A2) were carried out in the same manner as in Example 1, and the foam particles to which internal pressure had been applied were transported to hopper 3. The open-cell ratio of the foam particles in hopper 3 was measured using the method described above. The results are shown in Table 1. Next, the filling process was carried out in the same manner as in Example 1. Subsequently, the foam molding process was carried out in the same manner as in Example 1, except that the water vapor pressure (water vapor pressure A) during one-sided heating and reverse one-sided heating was changed to 0.05 MPa (gauge pressure), and the water vapor pressure (water vapor pressure B) during double-sided heating was changed to 0.11 MPa (gauge pressure), to obtain a foam molded body. The resulting foamed molded body was removed from the mold and dried at 75°C. The deformation of the dried foamed molded body was measured, and its surface properties were evaluated. The results are shown in Table 2.

[0143] The transport atmosphere temperature in the examples, comparative examples, and reference examples was set by heating the air introduced from the blower into each ejector using a steam heat exchanger and controlling the temperature of the heat exchanger. Furthermore, the transport atmosphere temperature in the examples, comparative examples, and reference examples was obtained by measuring it with a thermometer installed inside the transport pipe.

[0144] [Table 1]

[0145] [Table 2]

[0146] In Tables 1 and 2, "means" represents "means of transport," "B" represents "blower," and "E" represents "ejector." [Industrial applicability]

[0147] One embodiment of the present invention can be suitably used as a method for manufacturing foamed molded articles for various applications such as food containers, packaging materials, sanitary products, automotive parts (especially toolboxes, etc.), packaging cushioning materials (especially for home appliances), agricultural product boxes, fish boxes, logistics materials, heat insulation materials, and civil engineering and construction components. [Explanation of symbols]

[0148] 100 Molding equipment 200 Molding equipment 1 Bunker 2. Pressure vessel 3 Hopper 41 First Ejector 42 Second ejector 43 Third Ejector 51 First foamed particle transport tube 52 Second foamed particle transport tube 53 Third foamed particle transport tube 300 foamed molded body 301 Vertical wall section 302 Partition section 303 Bottom

Claims

1. A method for producing an aliphatic polyester resin foam molded article, comprising molding aliphatic polyester resin foam particles using a molding apparatus, (i) The molding apparatus described above is A bunker into which the aliphatic polyester resin foam particles are introduced, Pressure vessel and The system includes a hopper for containing the aliphatic polyester resin foam particles, The bunker and the pressure vessel are connected by a first ejector and a first foam particle transport pipe, and The pressure vessel and the hopper are connected by a second ejector and a second foam particle transport pipe. The method for producing the aliphatic polyester resin foam molded article is as follows: A transport step (A1) involves transporting the aliphatic polyester resin foam particles from the bunker to the pressure vessel using the first ejector through the first foam particle transport pipe, An internal pressure application step is performed to increase the pressure inside the pressure vessel and apply internal pressure to the aliphatic polyester resin foam particles. A pressure release step in which the pressure inside the pressure-resistant container is released while the aliphatic polyester resin foam particles, which have been subjected to internal pressure, are contained within the container, The transport process (A2) includes transporting the aliphatic polyester resin foam particles, which have internal pressure applied to them, from the pressure vessel to the hopper using the second ejector through the second foam particle transport pipe, or (ii) The molding apparatus described above is A bunker into which the aliphatic polyester resin foam particles are introduced, The system includes a hopper for containing the aliphatic polyester resin foam particles, Excluding pressure vessels, The bunker and the hopper are connected by a third ejector and a third foam particle transport pipe. The method for producing the aliphatic polyester resin foam molded article is as follows: A transport step (B) is provided in which the aliphatic polyester resin foam particles are transported from the bunker to the hopper using the third ejector, through the third foam particle transport pipe, A method for producing a foamed molded article of aliphatic polyester resin.

2. The method for producing an aliphatic polyester resin foam molded article according to claim 1, wherein the transport atmosphere temperature in one or more transport steps selected from the group consisting of transport step (A1), transport step (A2), and transport step (B) is 5°C to 60°C.

3. The method for producing an aliphatic polyester resin foam molded article according to claim 1 or 2, wherein the aliphatic polyester resin foam particles are poly(3-hydroxyalkanoate) resin foam particles.

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