Method for producing expanded bead molded body

Abstract

To provide a method for manufacturing a foamed particle molded article that can obtain a foamed particle molded article with a good surface and fusion condition while reducing an amount of steam used during in-mold molding.SOLUTION: There is provided a method for manufacturing a foamed particle molded article, wherein: a total steam amount Wd+f+s+b obtained from a steam amount Wd in a mold heating step P2, a steam amount Wf in a first one-side heating step P3, a steam amount Ws in a second one-side heating step P4 and a steam amount Wb in a double-side heating step P5 is 0.05 kg or more and 0.5 kg or less per 1 L of the molding space volume; a ratio of the steam amount Wd to the total amount Wf+s+b obtained from the steam amount Wf, the steam amount Ws, and the steam amount Wb is Wd:Wf+s+b=5:95 to 40:60; and when a total steam amount of Wf+s+b is set to 100 mass%, a ratio of the steam amount Wf is 15 mass% or more and 50 mass% or less, a ratio of the steam amount Ws is 15 mass% or more and 50 mass% or less, a ratio of the steam amount Wb is 10 mass% or more and 70 mass% or less, and a ratio of Wb / Wf is 0.3 or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing an expanded bead molding. [Background technology]

[0002] Expanded polystyrene resin bead molded articles obtained by in-mold molding of expanded polystyrene resin beads are lightweight and have excellent compression properties, and are therefore used in a variety of fields, including automotive materials, construction materials, and logistics materials. In-mold molding of expanded beads uses a mold that includes a first mold and a second mold, and is configured so that a molding cavity corresponding to the shape of the desired molded article is formed between the first mold and the second mold. After filling the molding cavity of such a mold with expanded beads, steam is supplied to the first mold and the second mold in a predetermined order to heat the expanded beads in the mold, thereby obtaining a molded article having the desired shape (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-237468 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there has been a demand for reducing the energy required for producing expanded bead moldings. From this perspective, there has been a demand for reducing the amount of steam used during in-mold molding. However, reducing the amount of steam used during in-mold molding could result in a decrease in the degree of fusion between the expanded beads in the molding, which could lead to a decrease in the physical properties of the molding. Furthermore, there is a risk that the surface condition of the molding could be deteriorated, resulting in a poor surface appearance of the molding.

[0005] The present invention has been made in view of the above background, and aims to provide a method for producing expanded bead moldings that can reduce the amount of steam used during in-mold molding while obtaining expanded bead moldings with good surface conditions and fusion conditions. [Means for solving the problem]

[0006] One aspect of the present invention resides in the method for producing an expanded bead molding according to the following items [1] to [5].

[0007] [1] A method for producing a foamed bead molded article, comprising: using a molding die having a first die and a second die configured to be able to form a molding space between the first die and the second die; and molding expanded polystyrene resin beads filled in the molding space to produce a foamed bead molded article, The method for producing the expanded bead molded article includes a filling step of filling the molding space with expanded polystyrene resin beads, a mold heating step of supplying steam into the molding space from both the first mold side and the second mold side after the filling step, a first one-side heating step of supplying steam into the molding space from the first mold side after the mold heating step, a second one-side heating step of supplying steam into the molding space from the second mold side after the first one-side heating step, a double-side heating step of supplying steam into the molding space from both the first mold side and the second mold side after the second one-side heating step, and a retaining step of retaining the steam supplied in the double-side heating step within the molding space, The amount of steam in the mold heating process W d and the amount of steam W in the first one-way heating step f and the amount of steam W in the second one-way heating step s and the steam amount W in the double-sided heating process b Total steam volume W d+f+s+b is 0.05 kg or more and 0.5 kg or less per 1 L of the volume of the molding space, The amount of steam in the mold heating process W d and the amount of steam W in the first one-way heating step. f and the amount of steam W in the second one-way heating step sand the steam amount W in the double-sided heating process b The total amount W f+s+b The ratio is W d :W f+s+b =5:95~40:60, The sum W of the amount of steam in the first one-side heating step, the amount of steam in the second one-side heating step, and the amount of steam in the double-side heating step f+s+b The amount of steam W in the first one-side heating step when the amount of steam W is 100% by mass f The ratio of the amount of steam in the second one-way heating step is 15 mass % or more and 50 mass % or less, and the amount of steam in the second one-way heating step is W s The ratio of is 15 mass % or more and 50 mass % or less, and the steam amount W b The proportion of is 10% by mass or more and 70% by mass or less, The amount of steam in the first one-way heating step W f The steam amount W in the double-sided heating process b Ratio of W b / W f is 0.3 or more the law of nature, The holding time in the holding step is 5 seconds or more. , a method for producing a foamed bead molding.

[0008] [2] The amount of steam W in the first one-side heating step f is 0.01 kg or more and 0.2 kg or less per 1 L of the volume of the molding space. [3] The amount of steam W in the first one-side heating step f The amount of steam in the mold heating process W d Ratio of W d / W f The method for producing an expanded bead molding according to [1] or [2], wherein the value of the expansion coefficient is 0.2 or more and 3 or less.

[0009] [4] The amount of steam W in the first one-side heating step f The amount of steam W in the second one-way heating step s Ratio of W s / W f The method for producing an expanded bead molding according to any one of [1] to [3], wherein the value is 0.6 or more and 2 or less. [5] The method for producing an expanded bead molding according to any one of [1] to [4], wherein the holding time in the holding step is from 5 seconds to 50 seconds. [Effects of the Invention]

[0010] According to the above aspect, it is possible to provide a method for producing an expanded bead molding that can reduce the amount of steam used during in-mold molding and obtain an expanded bead molding with a good surface condition and fusion state. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is an explanatory diagram showing a flow chart of a method for producing an expanded bead molding. [Figure 2] FIG. 2 is a partial cross-sectional view showing the main part of a molding die used for in-mold molding of expanded beads. [Figure 3] Figure 3(a) is a schematic diagram showing steam heating in a mold heating process, Figure 3(b) is a schematic diagram showing steam heating in a first one-side heating process, Figure 3(c) is a schematic diagram showing steam heating in a second one-side heating process, and Figure 3(d) is a schematic diagram showing steam heating in a double-side heating process. [Figure 4] FIG. 1 is a schematic diagram of steam heating in a holding step. [Figure 5] FIG. 1 is a schematic diagram of steam heating in the discharging process. DETAILED DESCRIPTION OF THE INVENTION

[0012] In this specification, "expanded polystyrene resin beads" may be referred to as "expanded beads," and "expanded bead moldings" may be referred to as "molded products." In addition, when the expression "to" is used in this specification, it is used in a sense that includes the numerical or physical values written before and after it.

[0013] The expanded bead molded article is produced, for example, by a molding die 1 (hereinafter also referred to as molding die 1) shown in Fig. 2. The molding die 1 comprises a first die 2 and a second die 3. At least one of the first die 2 and the second die 3 is configured to be movable in the opening and closing direction of the molding die 1. The first die 2 and the second die 3 are configured to abut against each other when the molding die 1 is fully closed, forming a molding space 11 between them. The molding space 11 may have any shape corresponding to the shape of the desired molded article.

[0014] The first mold 2 and the second mold 3 each have a hollow structure, and are configured so that the internal space of each mold communicates with the molding space 11. For example, the first mold 2 and the second mold 3 may have, in the inner wall portions 23, 33 facing the molding space 11, a plurality of core vents (not shown) that communicate between the internal space of each mold and the molding space 11. This allows steam supplied to the internal spaces of the first mold 2 and the second mold 3 to reach the molding space 11 through through grooves or the like formed in the core vents of the inner wall portions 23, 33. The through grooves are not shown.

[0015] Expanded bead molded articles are produced by molding expanded beads in a mold. As shown in Fig. 1, the method for producing expanded bead molded articles includes a filling step P1, a mold heating step P2, a first one-side heating step P3, a second one-side heating step P4, a double-side heating step P5, and a holding step P6. In the method for producing expanded bead molded articles, first, the filling step P1 is carried out, in which the molding space 11 is filled with expanded polystyrene resin beads. In the filling step P1, the molding space 11 of the molding die 1 is filled with expanded beads.

[0016] The foamed particles to be filled in the molding cavity 11 are not particularly limited as long as they are foamed particles whose base resin is a polystyrene-based resin, and known foamed polystyrene-based resin particles can be used. Here, the aforementioned polystyrene-based resin refers to a resin whose content of components derived from styrene is 50 mol % or more.

[0017] The expanded polystyrene resin particles can be obtained, for example, by expanding expandable polystyrene resin particles containing a polystyrene resin as a base resin and an organic physical blowing agent, such as hydrocarbons having 3 to 6 carbon atoms. The expanded particles may have a bulk density of 10 kg / m 3 200kg / m 3 The following expanded beads can be suitably used.

[0018] Expandable polystyrene-based resin particles can be produced by a conventionally known method such as suspension polymerization. Furthermore, a conventionally known method can be used to expand the expandable polystyrene-based resin particles. For example, a heating medium such as steam can be supplied to the expandable polystyrene-based resin particles to heat the expandable polystyrene-based resin particles, thereby expanding the expandable polystyrene-based resin particles. More specifically, for example, a cylindrical foaming machine equipped with a stirrer can be used to heat the expandable polystyrene-based resin particles with steam or the like, thereby expanding the expandable polystyrene-based resin particles.

[0019] The polystyrene-based resin may be a homopolymer of a styrene-based monomer or a copolymer containing a styrene-based monomer. More specifically, the polystyrene-based resin may be polystyrene (GPPS), a styrene-acrylic acid copolymer containing styrene as the main component, a styrene-methyl acrylate copolymer, a styrene-ethyl acrylate copolymer, a styrene-butyl acrylate copolymer, a styrene-methacrylic acid copolymer, a styrene-methyl methacrylate copolymer, a styrene-ethyl methacrylate copolymer, a styrene-butyl methacrylate copolymer, a styrene-maleic anhydride copolymer, a styrene-acrylonitrile copolymer, a styrene-acrylonitrile-butadiene copolymer, a styrene-methylstyrene copolymer, a styrene-dimethylstyrene copolymer, a styrene-ethylstyrene copolymer, or a styrene-diethylstyrene copolymer. From the viewpoint of being able to stably obtain expanded beads that have good in-mold moldability and can be used to mold expanded bead moldings with good mechanical properties, the content of styrene-derived components in the polystyrene-based resin is preferably 60 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and particularly preferably 90 mol% or more.

[0020] Figure 3 illustrates the mold heating step P2, the first one-side heating step P3, the second one-side heating step P4, and the double-side heating step P5. While the details of the configuration of the mold 1 are omitted in Figure 3, the mold 1 may have the same configuration as that shown in Figure 2. In Figure 3, arrows indicate an example of the flow of steam within the mold. The same applies to Figures 4 and 5. For the terms mold heating process, one-side heating process, and double-side heating process in this disclosure, reference can be made to the contents of the Collection of Well-Known and Commonly Used Techniques (Foam Molding) published by the Japan Patent Office (August 1982).

[0021] As shown in FIG. 3(a), in the mold heating step P2 performed after the filling step P1, steam is supplied to the molding space 11 from both the first mold 2 side and the second mold 3 side to heat the mold and the expanded beads in the molding space 11. In the mold heating step P2, for example, the steam supply valves 21, 31 and drain valves 22, 32 of each mold are all opened, and steam is supplied from the steam supply valves 21, 31. This allows the air in the molding space 11 to be evacuated and replaced with steam, while heating the expanded beads in the molding space 11 and the molding mold. Furthermore, this mold heating step P2 efficiently preheats the expanded beads and the molding mold for the double-side heating step P5 described below, thereby efficiently increasing the temperatures of the expanded beads and the molding mold. This prevents the amount of steam required in the first one-side heating step P3 or the second one-side heating step P4 described below from becoming excessively large, and allows the formation of a molded body to proceed with a relatively small amount of steam in the double-side heating step P5.

[0022] After the mold heating step P2 is completed, a first one-side heating step P3 is performed in which steam is supplied from the first mold 2 side to the molding space 11 to heat the expanded beads in the molding space 11. In the first one-side heating step P3, the first steam supply valve 21 of the first mold 2 and the second drain valve 32 of the second mold 3 are opened, and the other valves (specifically, the second steam supply valve 31 and the first drain valve 22) are closed while supplying steam from the first steam supply valve 21, thereby allowing steam to flow from the first mold 2 side to the second mold 3 side (see FIG. 3(b)). This primarily heats the first mold 2 side of the molding mold 1, and also heats the expanded beads in the molding space 11, mainly around the first mold 2 side of the molding mold 1. This also allows the foamed particles and mold to be efficiently preheated for the double-sided heating step P5 described below, preventing the amount of steam required in the second one-sided heating step P4 described below from becoming excessively large, and allows the formation of the molded body to proceed with a relatively small amount of steam in the double-sided heating step P5.

[0023] After the first one-side heating step P3 is completed, a second one-side heating step P4 is performed in which steam is supplied from the second mold 3 side to the molding space 11 to heat the expanded beads in the molding space 11. In the second one-side heating step P4, the second steam supply valve 31 of the second mold 3 and the first drain valve 22 of the first mold 2 are opened, and the other valves (specifically, the first steam supply valve 21 and the second drain valve 32) are closed while supplying steam from the second steam supply valve 31, thereby allowing steam to flow from the second mold 3 side to the first mold 2 side (see FIG. 3(c)). This primarily heats the second mold 3 side of the molding mold 1, and also heats the expanded beads in the molding space 11, mainly around the second mold 3 side of the molding mold 1. This also allows the expanded beads and the molding mold to be efficiently preheated for the double-side heating step P5, which will be described later, and allows the formation of a molded body to proceed with a relatively small amount of steam in the double-side heating step P5.

[0024] After the second one-side heating step P4 is completed, a double-side heating step P5 is performed in which steam is supplied to the molding space 11 from both the first mold 2 side and the second mold 3 side to heat the expanded beads in the molding space 11. In the double-side heating step P5, the first steam supply valve 21 of the first mold 2 and the second steam supply valve 31 of the second mold 3 are opened, and the first drain valve 22 and the second drain valve 32 of each mold are closed while supplying steam, thereby increasing the pressure in the molding space 11 (see FIG. 3(d)). This allows the expanded beads in the molding space 11 to be heated while increasing the pressure in the molding space 11. As a result, the expanded beads in the molding space 11 are fused together, filling the gaps between the expanded beads, and forming the surface of the molded body.

[0025] After the double-sided heating step P5 is completed, a holding step P6 is performed, in which the steam supplied in the double-sided heating step P5 is held within the molding mold 1, as shown in FIG. 1. In the in-mold molding method for producing a molded body, the heating performed up to the holding step P6 causes the foamed beads in the molding space 11 to undergo secondary expansion and fuse together, forming a molded body in which the foamed beads are fused together. In the holding step P6, the steam supply valves 21, 31 and drain valves 22, 32 of each mold are all closed, thereby slowing the decrease in the temperature and pressure in the molding space 11 that were increased in the double-sided heating step P5, and maintaining the temperature and pressure in the molding space 11 at a high level for a certain period of time without the need to supply new steam (see FIG. 4). This further heats the foamed beads in the molding space 11 without the need to use new steam. In this way, by carrying out steps P2 to P6 in order and supplying steam in each step in a specific relationship as described below, it is possible to further promote fusion between the expanded beads in the molding space 11, fill the gaps between the expanded beads, and improve the fusion state and surface condition of the molded body. Note that, as long as the temperature and pressure in the molding space after the double-side heating step can be maintained high for a certain period of time and the intended object of the present invention can be achieved, some of the steam in the molding space may be vented to the outside of the molding space in the holding step P6.

[0026] In the manufacturing method of the present disclosure, the expanded bead molding is produced by heating the mold P2 with a steam amount W d and the amount of steam W in the first one-way heating step P3 f and the amount of steam W in the second one-way heating step P4 s and the steam volume W in the double-sided heating process P5 b The relationship between the amount of steam used in each process is explained below.

[0027] In the manufacturing method, the amount of steam W in the mold heating step P2 d and the amount of steam W in the first one-way heating step P3 f and the amount of steam W in the second one-way heating step P4 s and the steam volume W in the double-sided heating process P5 b Total steam volume W d+f+s+b The total amount of steam W per 1 L of the volume of the molding space 11 is set to 0.05 kg or more and 0.5 kg or less. In the manufacturing method of the present disclosure, a foamed bead molding having a good surface condition and fusion state can be obtained with a relatively small total amount of steam within the above range. d+f+s+b If the total amount of steam W per 1 L of the volume of the molding space 11 is too small, the fusion state and surface condition of the molding may be deteriorated. d+f+s+b If the amount of steam used to obtain the molded body is excessively large, the amount of steam required to obtain the molded body will increase, making it impossible to reduce energy consumption. d+f+s+b is preferably 0.06 kg or more and 0.4 kg or less.

[0028] In the present disclosure, the amount of steam in each step generally refers to the amount of steam supplied to the interior space of the casting mold in each step from a steam supply valve provided for supplying steam to the interior space of the casting mold. This amount of steam can be determined, for example, by attaching a flow meter configured to be able to measure the cumulative flow rate of steam to a steam pipe connected to the steam supply valve and measuring the cumulative flow rate of steam supplied in each step. In in-mold molding, the amount of steam required to obtain a good molded body is affected by the size of the molding mold. Also, since there is a correlation between the size of the molding mold and the volume of the molding space, in this disclosure, the amount of steam supplied in each process is specified as the amount of steam per 1 L of the volume of the molding space 11. This makes it easier to determine the appropriate amount of steam required to obtain a good molded body while reducing the influence of the size of the molding mold used (the size of the molded body to be obtained). On the other hand, the volume of the molding space 11 is preferably approximately 5 L or more and 100 L or less, more preferably 10 L or more and 90 L or less, and even more preferably 15 L or more and 80 L or less. The volume of molding space 11 can be found, for example, from the dimensions of the inner wall of mold 1 used to form molding space 11, by calculating the volume of the space enclosed by the inner wall of each mold when the mold is closed. Furthermore, if the mold has multiple molding spaces and is a mold capable of molding multiple molded bodies in a single molding run (specifically, for example, a multi-cavity mold), the volume of the molding space is the sum of the volumes of the multiple molding spaces. The dimensions of the inner wall may be measured or calculated from drawings of the mold, etc.

[0029] Steam volume W in mold heating process P2 d and the amount of steam W in the first one-side heating step P3 f and the amount of steam W in the second one-way heating step P4 s and the steam volume W in the double-sided heating process P5 b The total amount W f+s+b The ratio of W d :W f+s+b = 5:95 to 40:60. In other words, the steam volume W d and steam volume W f and steam volume W s and steam volume W b Total steam volume W d+f+s+b The amount of steam W when the amount of steam is 100% by mass d The ratio of the amount of steam is 5% by mass or more and 40% by mass or less. By controlling the amount of steam in this way, the amount of steam W in the mold heating step P2 can be reduced. dThis allows the molding space 11 to be sufficiently heated at the beginning of molding. d+f+s+b The amount of steam W when the amount of steam is 100% by mass d If the ratio is too low, the air in the molding space 11 will not be sufficiently exhausted, making it difficult to heat the molding space 11 sufficiently in the mold heating step P2 and subsequent steps, which may result in a deterioration in the fusion state and surface condition of the resulting molded body. Also, the molding space 11 may not be heated efficiently, which may increase the overall amount of steam used. On the other hand, if the total amount of steam W d+f+s+b The amount of steam W when the amount of steam is 100% by mass d If the ratio of steam amount W is too high, the amount of steam available for other processes will be reduced under conditions where the total amount of steam used is reduced, which may result in a decrease in the fusion rate of the molded body or a deterioration in the surface condition of the molded body. d and steam volume W f and steam volume W s and steam volume W b The total amount W f+s+b The ratio of W d :W f+s+b = 10:90 to 40:60 is preferable, and W d :W f+s+b It is more preferable that the ratio is 15:85 to 35:65.

[0030] The sum W of the amount of steam in the first one-side heating step P3, the amount of steam in the second one-side heating step P4, and the amount of steam in the double-side heating step P5 f+s+b The amount of steam W in the first one-side heating step P3 when the amount of steam W is 100 mass% f The proportion of is 15 mass % or more and 50 mass % or less, and the amount of steam W in the second one-side heating step P4 s The ratio of is 15 mass % or more and 50 mass % or less, and the steam amount W b The ratio of the amount of steam in the first one-side heating step P3 is 10 mass % or more and 70 mass % or less. f The steam volume W of the double-sided heating process P5 b Ratio of W b / W fis 0.3 or more. By controlling the amount of steam in this manner, under conditions where the total amount of steam used is reduced, a predetermined amount of steam is used in the double-sided heating step P5, and steam is supplied so that the balance between the amount of steam in the first one-sided heating step P3 and the amount of steam in the second one-sided heating step P4 is not excessively unbalanced. This allows the molding space 11 to be preheated evenly, and then the expanded beads in the molding space 11 to be sufficiently heated by main heating. Furthermore, by setting the ratio of the amount of steam in the double-sided heating step P5 to the amount of steam in the first one-sided heating step P3 to be equal to or greater than a predetermined value, the expanded beads in the molding space are sufficiently heated and a sufficiently high pressure can be created in the molding space at the end of the double-sided heating step P5. By performing the holding step P6 after such a double-sided heating step P5, the temperature and pressure in the molding space after the double-sided heating step P5 can be maintained at a sufficiently high level for a long period of time, and the foamed particles can be sufficiently fused together without the need to supply new steam, while filling the gaps between the foamed particles.This reduces the amount of steam used during molding in the mold, and allows for the production of a molded product with good fusion and surface condition.

[0031] Steam amount W in the first one-side heating step P3 f If the ratio of the amount of steam W in the first one-side heating step P3 is too low, the temperature in the molding space 11 is likely to be uneven, and there is a risk that the fusion of the expanded particles with each other may be poor in some places. f If the ratio is excessively high, the amount of steam W in the first one-way heating step P3 f This may result in a large imbalance between the amount of steam in the first one-side heating step P3 and the second one-side heating step P4, which may cause uneven preheating in the molding space 11 before the double-side heating step P5. This may result in a decrease in the fusion rate of the molded body and a deterioration in the surface condition of the molded body. From this perspective, as described above, the total amount of steam W f+s+b The amount of steam W in the first one-side heating step P3 when the amount of steam W is 100 mass% f The proportion of is 15% by mass or more and 50% by mass or less. For example, the aforementioned Patent Document 1 describes that, while steam is supplied for a predetermined time or longer in the first one-sided heating step, which has the highest steam flow rate per unit time and requires the most steam, the overall amount of steam used can be reduced by establishing a specific relationship between the steam supply time in the one-sided heating step and the holding time in the holding step and shortening the steam supply time in the one-sided heating step. However, this method has been found to have the risk of reducing the fusion rate of the molded body and deteriorating the surface condition of the molded body, as described above, even if the holding step is performed. In the present disclosure, by supplying steam in each step and performing the holding step so that the amount of steam supplied in each step satisfies a predetermined relationship, it is possible to mold a molded body with a good surface condition and fusion state while reducing the amount of steam used to produce the molded body. The total amount of steam W supplied to the mold in the mold heating step, first one-side heating step, second one-side heating step, and double-side heating step (i.e., total amount of steam W) is preferably 8 kg or less, more preferably 7 kg or less. The total amount of steam W is preferably 2 kg or more, more preferably 3 kg or more, and even more preferably 4 kg or more.

[0032] The amount of steam W in the second one-way heating step P4 s If the ratio of is too low, the temperature in the molding space 11 is likely to be uneven, and there is a risk that the fusion of the expanded particles with each other may be poor in some places. s If the ratio is excessively high, the amount of steam W in the first one-way heating step P3 f This may result in a large imbalance between the amount of steam in the first one-side heating step P3 and the second one-side heating step P4, which may cause uneven preheating in the molding space 11 before the double-side heating step P5. This may result in a decrease in the fusion rate of the molded body and a deterioration in the surface condition of the molded body. From this perspective, as described above, the total amount of steam W f+s+bThe amount of steam W in the second one-side heating step P4 when the amount of steam W is 100 mass% s The proportion of is 15% by mass or more and 50% by mass or less.

[0033] Steam volume W in double-sided heating process P5 b If the ratio of is too low, the pressure in the molding space 11 cannot be sufficiently increased and the molding space 11 cannot be sufficiently heated, which may result in a decrease in the fusion rate of the molded body and a deterioration in the surface condition of the molded body. b If the ratio is excessively high, there is a risk that the amount of steam used in other steps will be insufficient under conditions where the overall amount of steam used is reduced. If the amount of steam used in the first one-side heating step P3 or the second one-side heating step P4 is insufficient, the temperature in the molding space 11 will be more likely to be uneven, and there is a risk that areas where the fusion of the expanded particles with each other will be poor will occur. Furthermore, if the amount of steam used in the mold heating step P2 is insufficient, the air in the molding space 11 will not be sufficiently exhausted, making it difficult to sufficiently heat the molding space 11 in the subsequent steps, and there is a risk that the fusion state and surface condition of the molded body obtained under conditions where the overall amount of steam used is reduced will deteriorate. From this perspective, as described above, the total amount of steam used in the first one-side heating step P3, the second one-side heating step P4, and the double-side heating step P5, W f+s+b The amount of steam W in the double-sided heating process P5 when the amount of steam W is 100% by mass b The proportion of is 10% by mass or more and 70% by mass or less.

[0034] In addition, the amount of steam W in the first one-side heating step P3 f The steam volume W of the double-sided heating process P5 b Ratio of W b / W f From the viewpoint of more easily and stably obtaining a molded article having a good surface condition, the ratio W is preferably 0.4 or more, and more preferably 0.5 or more. b / W f is preferably 4 or less, more preferably 3 or less, and even more preferably 2 or less.

[0035] In addition, the amount of steam W in the first one-side heating step P3 f Steam volume W in mold heating process P2 d Ratio of W d / W f is preferably 0.2 or more and 3 or less. In this case, while reducing the amount of steam, it becomes easier to form a state in which the molding space 11 is sufficiently heated in the early stage of molding, and it becomes easier to prevent deterioration of the surface appearance and deterioration of the fusion state. As a result, it becomes easier to obtain a molded body with good surface appearance and fusion properties. From this viewpoint, W d / W f is more preferably 0.3 or more and 2 or less, and further preferably 0.4 or more and 2 or less.

[0036] In addition, the amount of steam W in the first one-side heating step P3 f The amount of steam W in the second one-way heating step P4 s Ratio of W s / W f It is preferable that W is 0.6 or more and 2 or less. In this case, it is possible to reduce the amount of steam used in the in-mold molding, while making it easier to uniformly preheat the molding space 11 before the main heating in the double-sided heating step P5, and to stably obtain a molded body with a good surface appearance and fusion state. s / W f is more preferably 0.7 or more and 2 or less, and further preferably 0.8 or more and 2 or less.

[0037] In addition, the preferred amount of steam and steam conditions for each step in carrying out the manufacturing method of the present disclosure will be described below. The amount of steam in each step can be controlled, for example, by adjusting the steam pressure and steam supply time in each step. For example, the amount of steam can be increased by increasing the steam pressure or extending the supply time. On the other hand, the amount of steam can be reduced by decreasing the steam pressure or shortening the supply time.

[0038] Steam volume W in mold heating process P2 dis preferably 0.005 kg or more and 0.2 kg or less, and more preferably 0.01 kg or more and 0.1 kg or less, per 1 L of the volume of the molding space 11. In this case, the pressure Pd of the steam supplied to the first mold 2 and the second mold 3 is preferably 0.02 MPa (G) or more and 1 MPa (G) or less, and more preferably 0.03 MPa (G) or more and 0.06 MPa (G) or less. In the mold heating step P2, steam at the aforementioned pressure is preferably supplied for, for example, 1 to 5 seconds. In this specification, the unit of pressure "(G)" means that the pressure is a gauge pressure.

[0039] In addition, the amount of steam W in the first one-side heating step P3 f is preferably 0.01 kg or more and 0.2 kg or less per 1 L of the volume of the molding space 11. In this case, the amount of steam used in the first one-side heating step P3 can be reduced and the steam ratio in other steps can be increased while stably heating the molding space 11. From the viewpoint of being able to sufficiently heat the first one-side heating step while further increasing the steam ratio in other steps, the amount of steam W in the first one-side heating step P3 per 1 L of the volume of the molding space 11 is f It is more preferable that the weight is 0.015 kg or more and 0.1 kg or less.

[0040] In the first one-side heating step P3, the steam pressure P of the steam supplied to the first mold 2 f is preferably 0.02 MPa (G) or more and 1 MPa (G) or less, and more preferably 0.03 MPa (G) or more and 0.8 MPa (G) or less. In the first one-side heating step P3, steam at the aforementioned pressure is preferably supplied for, for example, 1 to 10 seconds.

[0041] In addition, the amount of steam W in the second one-side heating step P4 s is preferably 0.01 kg or more and 0.2 kg or less, and more preferably 0.02 kg or more and 0.1 kg or less per 1 L of the volume of the molding space 11. In this case, the steam pressure P sis preferably 0.02 MPa (G) or more and 1 MPa (G) or less, and more preferably 0.03 MPa (G) or more and 0.8 MPa (G) or less. In the second one-side heating step P4, steam at the aforementioned pressure is preferably supplied for, for example, 1 to 10 seconds.

[0042] Steam volume W in double-sided heating process P5 b is preferably 0.01 kg or more and 0.2 kg or less, and more preferably 0.02 kg or more and 0.1 kg or less per 1 L of the volume of the molding space 11. In this case, the steam pressure P b is preferably 0.02 MPa (G) or more and 1 MPa (G) or less, and more preferably 0.03 MPa (G) or more and 0.8 MPa (G) or less. In the second one-side heating step P4, steam at the aforementioned pressure is preferably supplied for, for example, 5 to 20 seconds.

[0043] In addition, the holding time t h The time is preferably 5 seconds or more and 50 seconds or less. In this case, the fusion of the expanded beads in the molding space 11 can be sufficiently promoted and the gaps between the expanded beads can be sufficiently filled while preventing the molding cycle from becoming excessively long. As a result, a molded body with a good fusion state and surface condition can be consistently obtained. Note that if the holding step P6 is not performed, the fusion rate of the molded body may decrease or the surface condition of the molded body may deteriorate, even if the amount of steam supplied in each step satisfies the predetermined relationship. In addition, from the viewpoint of improving the molding cycle and stably obtaining a molded body with a good fusion state and surface condition, the steam supply time t d and the steam supply time t f and the steam supply time t s and the steam supply time t b The holding time t of the holding step P6 for the sum of h The ratio of t h / (t d +t f +t s+t b ) is preferably 0.1 or more and 3 or less, and more preferably 0.2 or more and 2 or less.

[0044] After the holding step P6 is completed, the discharge step P7 can be carried out, as shown in Figure 1, in which steam is discharged from within the molding space 11. In the discharge step P7, the steam supply valves 21, 31 of each mold are closed, and the drain valves 22, 32 of each mold are opened, thereby discharging the steam from within the molding space 11 through the drain valves 22, 32 and depressurizing (see Figure 5). After the discharge step P7 is completed, a cooling step P8 can be carried out, as necessary, in which the molded body within the forming mold 1 is cooled. After the shape of the molded body within the forming mold 1 has been stabilized to a certain extent, the forming mold 1 can be opened to obtain the molded body.

[0045] In the manufacturing method, the amount, ratio, and distribution of steam used in the mold heating step P2, the first one-side heating step P3, the second one-side heating step P4, and the double-side heating step P5 are adjusted within specific ranges during the holding step, thereby enabling the amount of steam used during in-mold molding to be sufficiently reduced, and an expanded bead molding with good fusion and surface condition to be obtained. [Example]

[0046] (Example 1-1) An example of a method for producing an expanded bead molding is described below. In this example, expanded beads with a styrene-butyl acrylate copolymer as the base resin are used to produce a box-shaped molding measuring 410 mm in length, 410 mm in width, 410 mm in height, with side and bottom walls 20 mm thick.

[0047] The specific configuration of the mold 1 used in this example will be described with reference to Figure 2. In Figure 2, the shape of the molding space is abbreviated for ease of drawing. As shown in Figure 2, the mold 1 has a first mold 2 and a second mold 3. The first mold 2 is fixed, and the second mold 3 is configured to be able to move relative to the first mold 2 in the opening and closing direction of the mold 1. Between the first mold 2 and the second mold 3, there is provided a molding space 11 that can mold a molded body having the shape described above.

[0048] The first die 2 has a hollow structure. The first die 2 also has a first steam supply valve 21 configured to be able to supply steam from the outside of the forming die 1 to the internal space of the first die 2, and a first drain valve 22 configured to be able to discharge steam from the internal space of the first die 2 to the outside of the forming die 1. Although not shown in the figure, a plurality of core vents are drilled in the inner wall portion 23 of the first die 2 facing the molding space 11, which allow communication between the internal space of the first die 2 and the molding space 11.

[0049] In the internal space of the first mold 2, a first watering nozzle 24 configured to be able to spray water onto the inner wall portion 23 is provided.

[0050] In addition, a surface pressure gauge (not shown) configured to be able to measure the pressure (i.e., surface pressure) applied to the inner wall 23 is attached to the inner wall 23 of the first mold 2. The surface pressure gauge is provided near the center of the inner wall 23 when the first mold 2 is viewed from the second mold 3 along the mold clamping direction. More specifically, the surface pressure gauge is provided at a position on the inner wall 23 corresponding to near the center of a surface of the molded body that is 410 mm long and 410 mm wide. The expanded beads heated during the in-mold molding process undergo secondary expansion and fuse together to form a molded body. Therefore, by providing the surface pressure gauge on the inner wall 33, it is possible to easily grasp the progress of in-mold molding through changes in surface pressure accompanying the secondary expansion of the expanded beads. The surface pressure gauge may also be attached to the inner wall 33 of the second mold 3.

[0051] Although not shown in the figure, a flow meter (TVA type steam flow meter manufactured by Spirax Sarco) configured to be able to measure the cumulative flow rate of steam is attached to the steam pipe connected to the first steam supply valve 21 near the supply valve 21. This makes it possible to measure the cumulative flow rate of steam supplied from the first steam supply valve 21 to the first mold 2.

[0052] The second die 3 also has a hollow structure like the first die 2. The second die 3 also has a second steam supply valve 31 configured to be able to supply steam from the outside of the molding die 1 to the internal space of the second die 3, and a second drain valve 32 configured to be able to discharge steam from the internal space of the second die 3 to the outside of the molding die 1. Although not shown in the figure, the inner wall portion 33 of the second die 3 facing the molding space 11 is provided with a plurality of core vents that communicate between the internal space of the second die 3 and the molding space 11.

[0053] In the internal space of the second mold 3, a second water spray nozzle 34 configured to be able to spray water onto the inner wall portion 33 is provided.

[0054] Although not shown in the figure, a flow meter (TVA steam flow meter manufactured by Spirax Sarco) capable of measuring the cumulative flow rate of steam is attached near the steam supply valve 31 to the steam pipe connected to the second steam supply valve 31. This allows the amount and pressure of steam supplied from the second steam supply valve 31 to be measured. Specifically, a "VS1300-DeCo" manufactured by Daisen Kogyo Co., Ltd. was used as the molding machine, which controlled the pressure and supply time of the steam supplied in each process. The mold was capable of molding four of the box-shaped molded bodies (volume approximately 16 L) at a time, and the volume (total volume) of the molding space was 64 L. The amount of steam supplied in each process was calculated by measuring the cumulative flow rate of the steam supplied in each process using the flow meter attached to the steam pipe.

[0055] In this example, the in-mold molding of expanded beads is carried out according to the procedure shown in Figure 1. That is, first, a filling step P1 is carried out in which the molding space 11 of the molding die 1 is filled with expanded beads. The expanded beads used in this example are expanded polystyrene resin beads with a styrene-butyl acrylate copolymer as the base resin. Specifically, the expanded beads are obtained by expanding expandable polystyrene resin beads with a styrene-butyl acrylate copolymer containing 0.5% by mass of a component derived from butyl acrylate as the base resin. The bulk density of the expanded beads is 25 kg / m 3 The bulk density of the expanded beads can be measured by the following method.

[0056] First, the expanded particles are filled into a measuring cylinder, and the bottom of the measuring cylinder is lightly tapped on the floor several times to stabilize the filling height of the expanded particles in the measuring cylinder. After that, the bulk volume (unit: L) of the expanded particles is read from the scale on the measuring cylinder. Then, the mass (unit: g) of the expanded particles in the measuring cylinder is divided by the aforementioned bulk volume, and the value is converted into units to determine the bulk density (unit: kg / m) of the expanded particles. 3 ) can be obtained.

[0057] After the filling step P1 is completed, the mold heating step P2 is carried out in which steam is supplied to the molding space 11 from both the first mold 2 side and the second mold 3 side to heat the expanded beads in the molding space 11. In the mold heating step P2 of this example, with the first steam supply valve 21, the first drain valve 22, the second steam supply valve 31, and the second drain valve 32 shown in Fig. 2 open, steam is supplied from the first steam supply valve 21 to the first mold 2 and steam is supplied from the second steam supply valve 31 to the second mold 3. This replaces the air that has been stagnating in the internal spaces of the first mold 2 and the second mold 3 with steam, and also heats the molding mold 1 and the expanded beads in the molding space 11.

[0058] After the mold heating step P2 is completed, as shown in FIG. 1, a first one-side heating step P3 is performed in which steam is supplied from the first mold 2 side to the molding space 11 to heat the expanded beads in the molding space 11. In this example, the first steam supply valve 21 and the second drain valve 32 shown in FIG. 2 are opened, and the other valves are closed. In this state, steam is supplied from the first steam supply valve 21 to the first mold 2, thereby introducing the steam into the internal space of the first mold 2. The steam introduced into the internal space of the first mold 2 flows into the molding space 11 via a core vent provided in the internal wall 23 of the first mold 2 (see FIG. 3(b)). This heats the expanded beads in the molding space 11. The steam in the molding space 11 is then guided into the internal space of the second mold 3 via a core vent provided in the internal wall 33 of the second mold 3 and then discharged to the outside of the molding die 1 through the second drain valve 32.

[0059] After the first one-side heating step P3 is completed, as shown in FIG. 1, a second one-side heating step P4 is performed in which steam is supplied to the molding space 11 from the second mold 3 side to heat the expanded beads in the molding space 11. In this example, the second one-side heating step P4 involves opening the second steam supply valve 31 and the first drain valve 22 shown in FIG. 2, while closing the other valves. In this state, steam is supplied to the second mold 3 from the second steam supply valve 31, thereby introducing the steam into the internal space of the second mold 3. The steam introduced into the internal space of the second mold 3 flows into the molding space 11 via a core vent provided in the inner wall 33 of the second mold 3 (see FIG. 3(c)). This heats the expanded beads in the molding space 11. The steam in the molding space 11 is then guided into the internal space of the first mold 2 via a core vent provided in the inner wall 23 of the first mold 2 and then discharged to the outside of the molding mold 1 through the first drain valve 22.

[0060] After the second one-side heating step P4 is completed, as shown in FIG. 1, a double-side heating step P5 is carried out in which steam is supplied to the molding space 11 from both the first mold 2 side and the second mold 3 side to heat the expanded beads in the molding space 11. In this double-side heating step P5, the first steam supply valve 21 and the second steam supply valve 31 shown in FIG. 2 are opened, and the other valves 22 and 32 are closed. In this state, steam is supplied from the first steam supply valve 21 to the first mold 2 and from the second steam supply valve 31 to the second mold 3, thereby introducing steam into the internal spaces of the first mold 2 and the second mold 3. The steam introduced into the internal spaces of these molds flows into the molding space 11 through core vents provided in the inner walls 23 and 33 (see FIG. 3(d)). This increases the pressure in the molding space 11 and heats the expanded beads.

[0061] After the double-sided heating step P5 is completed, as shown in Figure 1, a holding step P6 is carried out in which the steam supplied to the first die 2 and the second die 3 in the double-sided heating step P5 is held within the molding die 1. In the holding step P6 of this example, all of the valves 21, 22, 31, and 32 shown in Figure 2 are closed to hold the steam within the molding die 1. This allows the pressure applied to the molding surface of the molding die 1 to decrease gradually, and the expanded beads within the molding space 11 to be heated under high pressure for a long period of time without supplying steam to the molding die 1 (see Figure 4).

[0062] After the holding step P6 is completed, a discharge step P7 is carried out to discharge the steam from the molding space 11, as shown in Fig. 1. In the discharge step P7 of this example, the drain valves 22 and 32 of the molds are opened while the steam supply valves 21 and 31 of the molds are closed. As a result, the steam in the molding space 11 is discharged from the drain valves 22 and 32, and pressure is reduced (see Fig. 5).

[0063] After the ejection step P7 is completed, a cooling step P8 is carried out to cool the molded body in the forming mold 1, as shown in Fig. 1. The cooling step P8 in this example includes a water cooling step in which water is sprayed onto the inner wall portions 23, 33 from the first water sprinkler nozzle 24 and the second water sprinkler nozzle 34 shown in Fig. 2, and a vacuum cooling step in which the internal spaces of the first mold 2 and the second mold 3 are depressurized after the water cooling step is completed.

[0064] In the water cooling step, water is sprayed onto the inner wall portions 23, 33 from the first sprinkler nozzle 24 and the second sprinkler nozzle 34. This reduces the temperature of the inner wall portions 23, 33 and also cools the molded body in contact with the inner wall portions 23, 33.

[0065] In the vacuum cooling step, a vacuum valve (not shown) provided on the mold 1 is opened, and the other valves are closed. In this state, the pressure inside the mold 1 is reduced by forcibly discharging the gas inside the mold 1 through the vacuum valve using a vacuum pump. When the pressure inside the mold 1 is reduced, the water sprayed inside the mold 1 in the water cooling step becomes more likely to evaporate. As the water evaporates, heat inside the mold 1 is taken away as latent heat of evaporation, so by reducing the pressure inside the mold 1, the mold 1 and the molded body can be cooled more quickly. After the vacuum cooling step is completed, the vacuum state inside the mold 1 is released by opening an exhaust valve (not shown) provided on the mold 1.

[0066] After the cooling step P8 is completed, the mold 1 is opened to obtain a molded body.

[0067] In this example, the steam pressures P in the mold heating step P2, the first one-side heating step P3, the second one-side heating step P4, and the double-side heating step P5 are d , P f , P s , P b , each steam amount W d , W f , W s , W b , steam supply time t d , t f , t s , t bwas adjusted as shown in Table 1. In addition, the holding time t h was adjusted as shown in Table 1. By adjusting the molding conditions in this way, an expanded bead molding was produced.

[0068] The fusion rate, surface condition, number of voids, and molding cycle of the molded body obtained as described above were examined as follows: These evaluations were carried out on the molded body molded in the molding space located at the farthest position from the first steam supply valve 21 and the second steam supply valve 31.

[0069] Fusion rate First, the molded body was folded into roughly equal parts and broken. To facilitate this process, the molded body may be pre-cut. Subsequently, 100 or more expanded beads exposed on the fracture surface of the molded body were randomly selected and visually observed to determine whether the expanded beads had broken internally (i.e., material fracture) or at the interface between the expanded beads (i.e., interfacial fracture). The ratio of the total number of expanded beads with material fracture to the total number of visually observed expanded beads, expressed as a percentage, was defined as the fusion rate (unit: %) of the molded body. The results are shown in Table 1. The fusion rate of the molded article is preferably 40% or more, which can be considered to be an expanded bead molded article in which the expanded beads are fused together.

[0070] Number of voids In a box-shaped foamed bead molding, a 100 mm x 100 mm square was drawn in the center of the outer surface of one of the side walls of the mold, which were facing each other in the left-right direction. The voids present within the square, i.e., the gaps formed between the foamed beads, were measured to determine whether they were 0.5 mm in diameter or smaller when viewed from above. 2 The number of voids having a size of 100 or more was counted. The number of voids measured was divided by the measured area, and the unit was converted to a unit area (cm 2 The number of voids per unit area was calculated. The results are shown in Table 1. The fewer the number of voids per unit area, the better the surface condition of the molded body.

[0071] Molding cycle The time required from the start of mold clamping to the release of the mold during in-mold molding was measured. The mold was opened when the pressure (surface pressure) applied to the inner wall of the mold in the cooling step P8 reached a gauge pressure of 0.02 MPa (G).

[0072] (Example 1-2) The molding conditions were changed as shown in Table 1, and the rest were the same as in Example 1-1.

[0073] (Examples 1-3) The molding conditions were changed as shown in Table 1, and the rest were the same as in Example 1-1.

[0074] (Comparative Example 1-1) The molding conditions were changed as shown in Table 1, and the rest were the same as in Example 1-1.

[0075] (Comparative Example 1-2) The molding conditions were changed as shown in Table 1, and the rest were the same as in Example 1-1.

[0076] (Comparative Examples 1-3) The molding conditions were changed as shown in Table 1, and the rest were the same as in Example 1-1.

[0077] (Comparative Examples 1-4) The molding conditions were changed as shown in Table 1, and the rest were the same as in Example 1-1.

[0078] [Table 1]

[0079] As can be seen from Table 1, according to the manufacturing conditions of Examples 1-1 to 1-3, molded articles with good fusion and surface conditions were produced while reducing the total amount of steam used during molding in the mold, compared to the manufacturing conditions of Comparative Example 1-1, which does not include a holding step. This is because the manufacturing methods of Examples 1-1 to 1-3 include a mold heating step, a first one-side heating step, a second one-side heating step, a double-sided heating step, and a holding step, and also reduce the total amount of steam W d+f+s+b This is because the steam amount in each of the mold heating step P2, the first one-side heating step P3, the second one-side heating step P4, and the double-side heating step P5 is set to a specific relationship while the steam amount in each of the mold heating step P2, the first one-side heating step P3, the second one-side heating step P4, and the double-side heating step P5 is set to a specific relationship. d :W f+s+b = 5:95~40:60, and the total W with the steam volume f+s+b The amount of steam W when the amount of steam is 100% by mass f is 15% by mass or more and 50% by mass or less, and the amount of steam W s is 15% by mass or more and 50% by mass or less, and the amount of steam W b is 10 mass % or more and 70 mass % or less, and further, W b / W f This is because we ensure that is 0.3 or more.

[0080] Comparative Example 1-1 is an example in which in-mold molding was performed under conditions that allowed for obtaining a molded product with good fusion and surface conditions without performing a holding step. In Comparative Example 1-1, a molded product with good fusion and surface conditions similar to those of Examples 1-1 to 1-3 was obtained, but the amount of steam used was greater. When the total steam amount of Comparative Example 1-1 was taken as 100%, the reduction rates of the total steam amount of Example 1-1, Example 1-2, and Example 1-3 relative to the total steam amount of Comparative Example 1-1 were 36%, 41%, and 33%, respectively. The molding cycle of Comparative Example 1-1 was 185 seconds, while that of Example 1-1 was 184 seconds, so that both had equivalent molding cycles. The molding cycles of Examples 1-2 and 1-3 were 176 seconds and 187 seconds, respectively.

[0081] In Comparative Example 1-2, the holding step was not performed and the total amount of steam was reduced to the same extent as in Example 1-1. In this case, the surface condition of the molded body was deteriorated.

[0082] In Comparative Example 1-3, the total amount of steam was reduced to the same extent as in Example 1-1, and the holding step was performed. However, the amount of steam W in the first one-side heating step P3 was f In this case, the surface condition of the molded body was deteriorated.

[0083] In Comparative Example 1-4, the total amount of steam and the amount of steam in the mold heating step were set to the same level as in Example 1-1, and the holding step was performed. However, the amount of steam W in the first one-side heating step P3 was f In this case, the surface condition deteriorated.

[0084] As can be seen from the comparison between the Examples and Comparative Examples, by carrying out the holding process and ensuring that the relationship between the amount of steam in each process satisfies a specific relationship, it is possible to reduce the amount of steam used during molding in the mold while maintaining good surface condition and fusion state of the molded body.

[0085] Example 2 In this example, expanded beads with polystyrene as the base resin are used to produce a block-shaped molded body measuring 800 mm in length, 200 mm in width, and 150 mm in height. Specifically, the expanded beads used in this example were obtained by expanding Styrodia (registered trademark) "XJ251N," an expandable polystyrene bead manufactured by JSP. The bulk density of the expanded beads was 17 kg / m 3The molding machine used was a VS1300-DeCo, similar to Example 1-1. The molding die was capable of molding two of the block-shaped bodies (volume approximately 24 L) at a time, and the volume of the molding space was 48 L.

[0086] In this example, a molded body was produced by the mold-in-mold molding method in the same manner as in Example 1-1, except that the molding conditions for the mold-in-mold molding were changed as shown in Table 2. Then, the same evaluations as in Example 1-1 were carried out. The results are shown in Table 2. The number of voids was calculated in the same manner as in Example 1-1, except that a 100 mm x 100 mm square was drawn in the center of the main surface (800 mm long x 200 mm wide) of the molded body.

[0087] (Comparative Example 2-1) The molding conditions were changed as shown in Table 2, and the rest were the same as in Example 2.

[0088] (Comparative Example 2-2) The molding conditions were changed as shown in Table 2, and the rest were the same as in Example 2.

[0089] [Table 2]

[0090] As can be seen from Table 2, under the manufacturing conditions of Example 2, a molded body with a good fusion state and surface condition was produced while reducing the total amount of steam used during in-mold molding compared to the manufacturing conditions of Comparative Example 2-1, which did not include a holding step. This is thought to be because, in Example 2, a holding step was performed, as in Example 1-1, and the relationship between the amount of steam used in each step was set to a specific relationship. Furthermore, in Example 2, a large block-shaped molded body was produced. Even in this case, by performing the holding step and controlling the amount of steam used in each step, it was possible to reduce the amount of steam used during in-mold molding and obtain a molded body with a good fusion state and surface condition.

[0091] Comparative Example 2-1 is an example in which in-mold molding was performed under conditions that allowed for obtaining a molded product with good fusion and surface conditions without performing a holding step. In Comparative Example 2-1, a molded product with good fusion and surface conditions similar to those of Example 2 was obtained, but the amount of steam used was greater. Note that when the total steam amount of Comparative Example 2-1 is taken as 100%, the reduction rate of the total steam amount of Example 2 relative to the total steam amount of Comparative Example 2-1 was 34%. Furthermore, the molding cycle in Comparative Example 2-1 was 158 seconds, whereas the molding cycle in Example 2 was 158 seconds, and both had equivalent molding cycles.

[0092] In Comparative Example 2-2, the total amount of steam was reduced to the same extent as in Example 2, and the holding step was performed. However, the amount of steam W in the first one-side heating step P3 was f In this case, the surface condition of the molded body deteriorated and the fusion rate of the molded body also decreased.

[0093] Example 3 In this example, a plate-shaped molded article measuring 910 mm in length, 595 mm in width, and 40 mm in thickness is manufactured using expanded beads containing a flame retardant and polystyrene as the base resin. Specifically, the expanded beads used in this example were obtained by expanding Styrodia (registered trademark) "FA201", an expandable polystyrene bead manufactured by JSP. The bulk density of the expanded beads was 25 kg / m 3 The molding machine used was the "VS2800S-S1" manufactured by Daisen Kogyo Co., Ltd. The volume of the molding space was 22L.

[0094] In this example, a molded body was produced by in-mold molding in the same manner as in Example 1-1, except that the molding conditions for in-mold molding were changed as shown in Table 3. Then, the same evaluations as in Example 1-1 were carried out. The results are shown in Table 3. The number of voids was calculated in the same manner as in Example 1-1, except that a 100 mm x 100 mm square was drawn in the center of the main surface of the molded body (a surface measuring 910 mm long x 595 mm wide).

[0095] (Comparative Example 3-1) The molding conditions were changed as shown in Table 3, and the rest were the same as in Example 3.

[0096] (Comparative Example 3-2) The molding conditions were changed as shown in Table 3, and the rest were the same as in Example 3.

[0097] [Table 3]

[0098] As can be seen from Table 3, under the production conditions of Example 3, a molded body with a good fusion state and surface condition was produced while reducing the total amount of steam used during in-mold molding compared to the production conditions of Comparative Example 3-1, which did not include a holding step. This is thought to be because, in Example 3, a holding step was performed, as in Examples 1-1 to 1-3 and Example 2, and the relationship between the amount of steam in each step was set to a specific relationship. Furthermore, in Example 3, a plate-shaped molded body was produced, which has a different shape from Example 2. Even in this case, by performing the holding step and controlling the amount of steam in each step, it is possible to reduce the amount of steam used during in-mold molding and obtain a molded body with a good fusion state and surface condition.

[0099] Comparative Example 3-1 is an example in which in-mold molding was performed under conditions that allowed for obtaining a molded product with good fusion and surface conditions without performing a holding step. In Comparative Example 3-1, a molded product with good fusion and surface conditions similar to those of Example 3 was obtained, but the amount of steam used was greater. Note that when the total steam amount of Comparative Example 3-1 is taken as 100%, the reduction rate of the total steam amount of Example 3 relative to the total steam amount of Comparative Example 3-1 was 39%. Furthermore, the molding cycle in Comparative Example 3-1 was 740 seconds, whereas the molding cycle in Example 3 was 735 seconds, and both had equivalent molding cycles.

[0100] In Comparative Example 3-2, the holding step was performed while reducing the total amount of steam to the same extent as in Example 3, but the amount of steam W in the first one-side heating step P3 was fIn this case, the surface condition of the molded body deteriorated and the fusion rate of the molded body also decreased.

[0101] Example 4 In this example, expanded beads with polystyrene as the base resin are used to produce a box-shaped molded body with a length of 350 mm, a width of 660 mm, a height of 250 mm, a side wall thickness of 30 mm, and a bottom wall thickness of 25 mm. Specifically, the expanded beads used in this example were obtained by expanding Styrodia (registered trademark) "JQ250NX", an expandable polystyrene bead manufactured by JSP. The bulk density of the expanded beads was 17 kg / m 3 The molding machine used was the "VS1300-MCJ" manufactured by Daisen Kogyo. The molding die is capable of molding two of the box-shaped bodies (volume approximately 18 L) at a time, and the volume (total volume) of the molding space is 36 L.

[0102] In this example, a molded body was produced by in-mold molding in the same manner as in Example 1-1, except that the molding conditions for in-mold molding were changed as shown in Table 4. Then, the same evaluations as in Example 1-1 were carried out. The results are shown in Table 4. The number of voids was calculated in the same manner as in Example 1-1, except that a 100 mm x 100 mm square was drawn in the center of the outer surface of one of the side walls facing each other in the left-right direction of the mold.

[0103] (Comparative Example 4-1) The molding conditions were changed as shown in Table 4, and the rest were the same as in Example 4.

[0104] (Comparative Example 4-2) The molding conditions were changed as shown in Table 4, and the rest were the same as in Example 4.

[0105] [Table 4]

[0106] As can be seen from Table 4, under the production conditions of Example 4, compared to the production conditions of Comparative Example 4-1, which does not include a holding step, a molded body with a good fusion state and surface condition was produced while reducing the total amount of steam used during in-mold molding. This is thought to be because, in Example 4, a holding step was performed, as in Examples 1-1 to 1-3, Example 2, and Example 3, and the steam amounts in each step were set to a specific relationship. Furthermore, in Example 4, a box-shaped molded body with thicker side walls and bottom walls was produced than the box-shaped molded bodies of Examples 1-1 to 1-3. Even in this case, by performing the holding step and controlling the amount of steam in each step, a molded body with a good fusion state and surface condition could be obtained while reducing the amount of steam used during in-mold molding.

[0107] Comparative Example 4-1 is an example in which in-mold molding was performed under conditions that allowed for obtaining a molded product with good fusion and surface conditions without performing a holding step. In Comparative Example 4-1, a molded product with good fusion and surface conditions similar to those of Example 1-1 was obtained, but the amount of steam used was greater. Note that when the total steam amount of Comparative Example 4-1 is taken as 100%, the reduction rate of the total steam amount of Example 4 relative to the total steam amount of Comparative Example 4-1 was 28%. Furthermore, the molding cycle in Comparative Example 4-1 was 451 seconds, while the molding cycle in Example 4 was 456 seconds, and both had equivalent molding cycles.

[0108] In Comparative Example 4-2, the holding step was performed while reducing the total amount of steam to the same extent as in Example 4, but the amount of steam W in the first one-side heating step P3 was f In this case, the surface condition of the molded body deteriorated and the fusion rate of the molded body also decreased. [Explanation of symbols]

[0109] 1 mold 11 Molding space 2. First Type 3. Second Type

Claims

1. A method for manufacturing a foamed particle molded body, which uses a molding die including a first mold and a second mold configured to be able to form a molding space between the first mold and the second mold, and performs in-mold molding on polystyrene-based resin foamed particles filled in the molding space to manufacture a foamed particle molded body, the method for manufacturing the foamed particle molded body includes a filling step of filling the molding space with polystyrene-based resin foamed particles, a mold heating step of supplying steam to the molding space from both the first mold side and the second mold side after the filling step, a first one-sided heating step of supplying steam to the molding space from the first mold side after the mold heating step, a second one-sided heating step of supplying steam to the molding space from the second mold side after the first one-sided heating step, a double-sided heating step of supplying steam to the molding space from both the first mold side and the second mold side after the second one-sided heating step, and a holding step of holding the steam supplied in the double-sided heating step in the molding space, The steam amount W in the mold heating process d and the steam amount W in the first one-sided heating process f and the steam amount W in the second one-sided heating process s and the steam amount W in the double-sided heating process b The total steam amount W with d+f+s+b is 0.05 kg or more and 0.5 kg or less per 1 L of the volume of the molding space, The steam amount W in the mold heating process d and the steam amount W in the first one-sided heating process f and the steam amount W in the second one-sided heating process s and the steam amount W in the double-sided heating process b and the total amount W f+s+b The ratio to is W d :W f+s+b = 5:95 to 40:60, The total amount of steam W of the steam amount in the first one-sided heating step, the steam amount in the second one-sided heating step, and the steam amount in the double-sided heating step f+s+b When taking it as 100% by mass, the proportion of the steam amount W f in the first one-sided heating step is 15% by mass or more and 50% by mass or less, and the steam amount W s in the second one-sided heating step is 15% by mass or more and 50% by mass or less, and the steam amount W b in the double-sided heating step is 10% by mass or more and 70% by mass or less, The steam amount W in the first one-sided heating step f to the steam amount W in the double-sided heating step b of the ratio W b / W f is 0.3 or more, the method for manufacturing a foamed particle molded body, wherein the holding time in the holding step is 5 seconds or more.

2. The steam amount W in the first one-side heating step f is 0.01 kg or more and 0.2 kg or less per 1 L of the volume of the molding space, and the method for producing a foamed particle molded body according to claim 1.

3. The steam amount W of the first one-sided heating step f to the steam amount W of the mold heating step d of the ratio W d / W f is 0.2 or more and 3 or less, and the method for producing a foamed particle molded body according to claim 1 or 2.

4. The steam amount W in the first one-side heating step f to the steam amount W in the second one-side heating step s of the ratio W s / W f is 0.6 or more and 2 or less, and the method for producing a foamed particle molded body according to claim 1 or 2.

5. The method for manufacturing a foamed particle molded body according to claim 1 or 2, wherein the holding time in the holding step is 5 seconds or more and 50 seconds or less.

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