Method for manufacturing foamed particle molded article

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] Polystyrene-based resin expanded bead molded bodies obtained by molding expanded polystyrene-based resin beads in a mold are lightweight and have excellent compression properties, and therefore are used in various fields such as automobile materials, construction materials, and logistics materials. For molding expanded beads in a mold, a mold is used that includes a first mold and a second mold and is configured so that a molding cavity corresponding to the shape of a desired molded body 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 body having a desired shape (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-237468 A 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, and from this perspective, there has been a demand for reducing the amount of steam used during in-mold molding. However, if the amount of steam used during in-mold molding is reduced, there is a risk that the fusion state between the expanded beads in the molding will be reduced, resulting in a deterioration in the physical properties of the molding. In addition, there is a risk that the surface condition of the molding will be deteriorated, resulting in a deterioration in the 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 an expanded bead molding that can reduce the amount of steam used during in-mold molding while obtaining an expanded bead molding having a good surface condition and fusion state. [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 an expanded bead molding, comprising: using a molding die having a first die and a second die configured to be capable of forming a molding space between the first die and the second die; and in-mold molding polystyrene-based resin expanded beads filled in the molding space to produce an expanded bead molding, The method for producing the expanded bead molded product includes a filling step of filling the molding space with expanded polystyrene resin beads, a mold heating step of supplying steam from both the first mold side and the second mold side to the molding space after the filling step, a first one-side heating step of supplying steam from the first mold side to the molding space after the mold heating step, a second one-side heating step of supplying steam from the second mold side to the molding space after the first one-side heating step, a double-sided heating step of supplying steam from both the first mold side and the second mold side to the molding space after the second one-side heating step, and a retaining step of retaining the steam supplied in the double-sided heating step in 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 amount of steam in the double-sided heating process W b The 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 amount of steam in the double-sided heating process W b The total amount W f+s+b The ratio of 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-sided heating step f+s+b The amount of steam W in the first one-way heating step when the amount of steam W is 100% by mass f The ratio of is 15 mass% or more and 50 mass% or less, and the steam amount W s The ratio of is 15% by mass or more and 50% by 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 W in the first one-way heating step f The amount of steam W in the double-sided heating process b Ratio of W b / W f The method for producing an expanded bead molding, wherein the ratio of the expanded bead molding to the total mass of the expanded bead molding is 0.3 or more.

[0008] [2] The amount of steam W in the first one-way heating step f is 0.01 kg or more and 0.2 kg or less per 1 L of volume of the molding space. [3] The amount of steam W in the first one-way 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

[0009] [4] The amount of steam W in the first one-way 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. Effect of the Invention

[0010] According to the above aspect, it is possible to provide a method for producing an expanded bead molding, which can reduce the amount of steam used during in-mold molding and can provide an expanded bead molding having a good surface condition and fusion state. [Brief description 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. [Diagram 2] FIG. 2 is a partial cross-sectional view showing a main part of a molding die used for in-mold molding of expanded beads. [Diagram 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-sided heating process. [Figure 4] FIG. 2 is a schematic diagram of steam heating in the holding step. [Diagram 5] FIG. 2 is a schematic diagram of steam heating in the discharging process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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 "~" is used in this specification, it is used to include the numerical values ​​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 includes 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 in a completely closed state, so that a molding space 11 is formed between them. The molding space 11 may have any shape that corresponds 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 a plurality of core vents (not shown) in the inner wall parts 23, 33 facing the molding space 11, which communicate between the internal space of each mold and the molding space 11. This allows steam supplied to the internal space of the first mold 2 and the second mold 3 to reach the molding space 11 through through grooves formed in the core vents of the inner wall parts 23, 33. Illustration of the through grooves is omitted.

[0015] The expanded bead molding is manufactured by molding expanded beads in a mold. As shown in Fig. 1, the manufacturing method of the expanded bead molding 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-sided heating step P5, and a holding step P6. In the manufacturing method of the expanded bead molding, first, the filling step P1 is performed 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 expanded particles to be filled in the molding space 11 are not particularly limited as long as they are expanded particles having a polystyrene-based resin as a base resin, and known expanded polystyrene-based resin particles can be used. Here, the above-mentioned polystyrene-based resin refers to a resin having a content of 50 mol % or more of a component derived from styrene.

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

[0018] The expandable polystyrene resin particles can be produced by a conventionally known method such as suspension polymerization. In addition, the expandable polystyrene resin particles can be expanded by a conventionally known method. For example, a heating medium such as steam is supplied to the expandable polystyrene resin particles, and the expandable polystyrene resin particles are heated to expand the expandable polystyrene resin particles. More specifically, the expandable polystyrene resin particles can be expanded by heating the expandable polystyrene resin particles with steam or the like using a cylindrical expansion machine equipped with a stirrer.

[0019] As the polystyrene-based resin, a homopolymer of a styrene-based monomer and a copolymer containing a styrene-based monomer can be used. More specifically, the polystyrene-based resin may be a styrene-acrylic acid copolymer, 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, a styrene-diethylstyrene copolymer, or the like, which is mainly composed of polystyrene (GPPS) or styrene. From the viewpoint of being able to stably obtain expanded beads capable of being molded into expanded bead moldings having good in-mold moldability and good mechanical properties, the content of components derived from styrene 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] Fig. 3 illustrates the mold heating step P2, the first one-side heating step P3, the second one-side heating step P4, and the double-sided heating step P5. Although the details of the configuration of the mold 1 are omitted in Fig. 3, the mold 1 used may have the same configuration as that in Fig. 2. In Fig. 3, an example of the flow of steam in the mold is shown by arrows. The same applies to Figs. 4 and 5. For the terms mold heating process, one-side heating process, and double-sided heating process in this disclosure, reference may 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 foamed beads in the molding space 11. In the mold heating step P2, for example, the steam supply valves 21, 31 and the drain valves 22, 32 of each mold are all opened, and steam is supplied from the steam supply valves 21, 31. This allows the foamed beads in the molding space 11 to be heated and the mold to be heated while exhausting the air in the molding space 11 and replacing it with steam. In addition, this mold heating step P2 allows the foamed beads and the mold to be efficiently preheated toward the double-sided heating step P5 described later, and the temperatures of the foamed beads and the mold to be efficiently increased. This allows the formation of a molded body to proceed with a relatively small amount of steam in the double-sided heating step P5, while preventing the amount of steam required in the first one-sided heating step P3 or the second one-sided heating step P4 described later from becoming excessively large.

[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 die 2 side to the molding space 11 to heat the foamed beads in the molding space 11. In the first one-side heating step P3, the first steam supply valve 21 of the first die 2 and the second drain valve 32 of the second die 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, so that steam can flow from the first die 2 side to the second die 3 side (see FIG. 3(b)). As a result, the first die 2 side of the molding die 1 is mainly heated, and the foamed beads in the molding space 11 can be heated mainly on the first die 2 side of the molding die 1. This also makes it possible to efficiently preheat the foamed particles and the mold for the double-sided heating process P5 described below, and enables the formation of the molded body to proceed with a relatively small amount of steam in the double-sided heating process P5 while preventing the amount of steam required in the second one-sided heating process P4 described below from becoming excessively large.

[0023] After the first one-sided heating step P3 is completed, the second one-sided heating step P4 is performed in which steam is supplied from the second mold 3 side to the molding space 11 to heat the foamed beads in the molding space 11. In the second one-sided 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, so that steam can flow from the second mold 3 side to the first mold 2 side (see FIG. 3(c)). As a result, the second mold 3 side of the molding mold 1 is mainly heated, and the foamed beads in the molding space 11 can be heated mainly around the second mold 3 side of the molding mold 1. In addition, as a result, the foamed beads and the molding mold can be efficiently preheated for the double-sided heating step P5 described later, and the formation of the molded body can be advanced with a relatively small amount of steam in the double-sided heating step P5.

[0024] After the second one-sided heating step P4 is completed, a double-sided 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 foamed particles in the molding space 11. In the double-sided 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 makes it possible to increase the pressure in the molding space 11 while heating the foamed particles in the molding space 11. As a result, the foamed particles are fused to each other in the molding space 11, and the gaps between the foamed particles are filled, thereby progressing the formation of the surface of the molded body.

[0025] After the double-sided heating step P5 is completed, as shown in FIG. 1, a holding step P6 is performed in which the steam supplied in the double-sided heating step P5 is held in the mold 1. In the manufacturing method of a molded body by the in-mold molding method, the heating performed up to the holding step P6 causes the foamed particles in the molding space 11 to undergo secondary expansion while fusing with each other, thereby forming a molded body in which the foamed particles are fused with each other. In the holding step P6, the steam supply valves 21, 31 and the drain valves 22, 32 of each mold are all closed, so that the temperature and pressure in the molding space 11 increased in the double-sided heating step P5 are gradually decreased, and the temperature and pressure in the molding space 11 can be maintained high for a certain period of time without supplying new steam (see FIG. 4). This allows the foamed particles in the molding space 11 to be further heated without using new steam. In this way, by carrying out steps P2 to P6 in order and supplying steam in each step in a specific relationship described later, it is possible to further promote fusion between the expanded beads in the molding space 11 and fill the gaps between the expanded beads, thereby improving the fusion state and surface state of the molded body. Note that, as long as the temperature and pressure in the molding space after the double-sided heating step can be maintained high for a certain period of time within a range in which the intended object of the present invention can be achieved, part of the steam in the molding space may be exhausted to the outside of the molding space in the holding step P6.

[0026] In the manufacturing method of the present disclosure, the foamed bead molding is formed by heating the mold 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 amount of steam in the double-sided heating process P5 W 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 process 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 amount of steam in the double-sided heating process P5 W b The 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 state of the molded body may deteriorate. d+f+s+b If the total steam amount W per 1 L of the volume of the molding space 11 is excessively large, the amount of steam required to obtain a molded body increases, making it impossible to reduce energy consumption. d+f+s+b It is preferable that the weight is 0.06 kg or more and 0.4 kg or less.

[0028] In the present disclosure, the amount of steam in each step usually means the amount of steam supplied to the inner space of the casting mold in each step from a steam supply valve provided for supplying steam to the inner space of the casting mold. Such a steam amount can be determined, for example, by attaching a flowmeter configured to be able to measure the integrated flow rate of steam to a steam pipe connected to the steam supply valve and measuring the integrated flow rate of steam supplied in each step. In addition, the amount of steam required to obtain a good molded body in the in-mold molding is affected by the size of the mold. Also, since there is a correlation between the size of the 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 grasp the appropriate amount of steam required to obtain a good molded body while reducing the influence of the size of the mold used (the size of the molded body to be obtained). On the other hand, the volume of the molding space 11 is preferably about 5L or more and 100L or less, more preferably 10L or more and 90L or less, and even more preferably 15L or more and 80L or less. The volume of molding space 11 can be found, for example, from the dimensions of the inner wall of mold 1 for forming molding space 11, by calculating the volume of the space surrounded by the inner wall of each mold when the mold is closed. In addition, when the mold has multiple molding spaces and is a mold capable of molding multiple molded bodies in one molding (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 actually measured, or may be calculated from a drawing of the mold, etc.

[0029] Steam volume W in mold heating process 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 amount 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 = 5:95~40:60. In other words, the amount of steam W d and steam volume W f and steam volume W s and steam volume W b The total steam volume W d+f+s+b The amount of steam W when the mass percentage is 100% d The ratio of is 5 mass% or more and 40 mass% or less. By controlling the amount of steam in this way, the amount of steam W in the mold heating process P2 is 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 mass percentage is 100% d If the ratio of is too low, the air in the molding space 11 is not 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 poor fusion and surface condition of the resulting molded body. In addition, the molding space 11 may not be efficiently heated, 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 mass percentage is 100% d If the ratio of steam amount W is too high, the amount of steam available for other processes will be reduced under conditions of reduced overall steam consumption, and the fusion rate of the molded body may decrease or the surface condition of the molded body may deteriorate. 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, 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-sided 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 ratio of is 15 mass% or more and 50 mass% or less, and the steam amount W 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 amount of steam W in 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 way, under conditions where the total amount of steam used in the double-sided heating step P5 is reduced, the 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 biased while ensuring a predetermined amount of steam to be used in the double-sided heating step P5. This allows the molding space 11 to be preheated evenly, and then the foamed 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 a predetermined value or more, at the end of the double-sided heating step P5, the foamed beads in the molding space are sufficiently heated and a state in which the pressure in the molding space is sufficiently high can be formed. 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 state for a long time, and the foamed particles can be sufficiently fused to each other without supplying new steam, and the gaps between the foamed particles can be filled.This makes it possible to obtain a molded body with good fusion and surface condition while reducing the amount of steam used during molding in the mold.

[0031] Amount of steam W in the first one-way heating step P3 f 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 foamed particles with each other may be poor in some places. f When the ratio is excessively high, the amount of steam W in the first one-side heating step P3 is f There is a risk that the bias between the amount of steam in the first one-side heating step P3 and the second one-side heating step P4 and the amount of steam in the double-side heating step P5 will become large, and preheating unevenness will occur 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 viewpoint, 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 mass % or more and 50 mass % or less. For example, the above-mentioned Patent Document 1 describes that, on the premise that steam is supplied for a predetermined time or more in the first one-sided heating step, which has the highest steam flow rate per unit time and requires a large amount of steam, the steam supply time in the one-sided heating step and the holding time in the holding step are in a specific relationship, and the steam supply time in the one-sided heating step is shortened, thereby reducing the amount of steam used overall. However, in this method, it was found that, as described above, even if the holding step is performed, if the amount of steam used overall is further reduced, the fusion rate of the molded body may decrease and the surface condition of the molded body may deteriorate. 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 in the production of the molded body. The total amount W of steam supplied to the mold in the mold heating step, the first one-side heating step, the second one-side heating step, and the double-sided heating step (i.e., the total amount W of steam) is preferably 8 kg or less, more preferably 7 kg or less. The total amount W of steam 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 foamed particles with each other may be poor in some places. s When the ratio is excessively high, the amount of steam W in the first one-side heating step P3 is f There is a risk that the bias between the amount of steam in the first one-side heating step P3 and the amount of steam in the second one-side heating step P4 and the amount of steam in the both-side heating step P5 will become large, and that uneven preheating will occur in the molding space 11 before the both-side heating step P5. This may result in a decrease in the fusion rate of the molded body and a decrease 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-way heating step P4 when the amount of steam W is 100 mass% s The proportion of is 15 mass % or more and 50 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, so that the fusion rate of the molded body may decrease and the surface condition of the molded body may deteriorate. b If the ratio is excessively high, there is a risk that the amount of steam in other steps will be insufficient under conditions where the overall amount of steam used is reduced. If the amount of steam 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 is likely to become uneven, and there is a risk that the foamed particles will not fuse together properly in some places. Furthermore, if the amount of steam 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 the fusion state and surface state of the molded body obtained under conditions where the overall amount of steam used is reduced may deteriorate. From this perspective, as described above, the total amount of steam W of the first one-side heating step P3, the second one-side heating step P4, and the double-sided heating step P5 is set to 100%. 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 mass % or more and 70 mass % or less.

[0034] In addition, the amount of steam W in the first one-way heating step P3 f The amount of steam W in 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-way 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-way 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, while reducing the amount of steam used in the in-mold molding, it becomes easier to preheat the molding space 11 uniformly before the main heating in the double-sided heating step P5, and a molded body with a good surface appearance and fusion state can be stably obtained. 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 lengthening 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, more preferably 0.01 kg or more and 0.1 kg or less, per 1 L of the volume of the molding space 11. At this time, 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, more preferably 0.03 MPa (G) or more and 0.06 MPa (G) or less. In addition, in the mold heating step P2, it is preferable to supply steam of the above-mentioned pressure for, for example, 1 to 5 seconds. In addition, in this specification, the "(G)" attached to the unit of pressure means that the pressure is a gauge pressure.

[0039] In addition, the amount of steam W in the first one-way 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-way heating step P3 can be reduced to increase the steam ratio in other steps while stably heating the molding space 11. From the viewpoint of being able to increase the steam ratio in other steps while sufficiently heating in the first one-way heating step, the amount of steam W in the first one-way heating step P3 per 1 L of the volume of the molding space 11 is preferably 0.01 kg or more and 0.2 kg or less. 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 is 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-way 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-sided 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-sided 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 between the expanded particles in the molding space 11 can be sufficiently promoted and the gaps between the expanded particles can be sufficiently filled while preventing the molding cycle from being excessively long. As a result, a molded body having a good fusion state and surface condition can be stably obtained. Note that if the holding step P6 is not performed, the fusion rate of the molded body may decrease and the surface condition of the molded body may deteriorate even if the amount of steam supplied in each step satisfies a predetermined relationship. In addition, from the viewpoint of improving the molding cycle and stably obtaining a molded body having a good fusion state and surface state, the steam supply time t d and the steam supply time t f and the steam supply time t s and 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, a discharge step P7 can be performed to discharge the steam from within the molding space 11, as shown in Fig. 1. 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 to discharge the steam from within the molding space 11 through the drain valves 22, 32, thereby depressurizing the space (see Fig. 5). After the discharge step P7 is completed, a cooling step P8 can be performed as necessary to cool the molded body within the molding die 1. The mold 1 can be opened after the shape of the molded body has been stabilized to a certain extent within the molding die 1, thereby obtaining the molded body.

[0045] In the above-mentioned 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 while the holding step is carried out. This makes it possible to obtain an expanded bead molding having a good fusion state and surface condition while sufficiently reducing the amount of steam used during molding in the mold. EXAMPLES

[0046] (Example 1-1) An example of the manufacturing method of the expanded bead molding is described below. In this example, expanded beads having a base resin of styrene-butyl acrylate copolymer are used to manufacture a box-shaped molding having a length of 410 mm, a width of 410 mm, a height of 410 mm, and side and bottom wall thicknesses of 20 mm.

[0047] The specific configuration of the mold 1 used in this example will be described with reference to Fig. 2. In Fig. 2, the shape of the molding space is omitted for convenience of drawing. As shown in Fig. 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 so as to be movable in the opening and closing direction of the mold 1 relative to the first mold 2. Between the first mold 2 and the second mold 3, a molding space 11 capable of molding a molded body having the above-mentioned shape is provided.

[0048] The first die 2 has a hollow structure. The first die 2 has a first steam supply valve 21 configured to be able to supply steam from the outside of the molding die 1 to the internal space of the first die 2, and a first drain valve 22 configured to be able to lead steam from the internal space of the first die 2 to the outside of the molding 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 communicate 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 the center of a surface of the molded body that is 410 mm long and 410 mm wide. The expanded particles heated during the in-mold molding process fuse together while undergoing secondary expansion to form a molded body. Therefore, by providing the surface pressure gauge on the inner wall 33, the progress of the in-mold molding can be easily grasped through the change in surface pressure accompanying the secondary expansion of the expanded particles. The surface pressure gauge may be attached to the inner wall 33 of the second mold 3.

[0051] Although not shown in the figure, a flowmeter (TVA steam flowmeter manufactured by Spirax Sarco) configured to be able to measure the cumulative flow rate of steam is attached to the steam piping 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 has one 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 one second drain valve 32 configured to be able to lead steam from the internal space of the second die 3 to the outside of the molding die 1. Although not shown in the figure, a plurality of core vents are drilled in the inner wall portion 33 facing the molding space 11 in the second die 3 to 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 flowmeter (TVA steam flowmeter manufactured by Spirax Sarco) configured to be able to measure the cumulative flow rate of steam is attached near the 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 the second mold 3 to be measured. Specifically, a "VS1300-DeCo" manufactured by Daisen Kogyo Co., Ltd. was used as the molding machine, which was used to control the pressure and supply time of the steam supplied in each process. In addition, the molding mold can mold four box-shaped molded bodies (volume approximately 16 L) in one molding, and the volume (total volume) of the molding space is 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 a flowmeter 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 Fig. 1. That is, first, a filling step P1 is carried out to fill the molding space 11 of the molding die 1 with expanded beads. The expanded beads used in this example are polystyrene-based resin expanded beads having a styrene-butyl acrylate copolymer as the base resin. Specifically, the expanded beads are obtained by expanding expandable polystyrene-based resin beads having a styrene-butyl acrylate copolymer as the base resin containing 0.5 mass % of a component derived from butyl acrylate. 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, fill a measuring cylinder with expanded particles and lightly tap the floor surface with the bottom of the measuring cylinder several times to stabilize the filling height of the expanded particles in the measuring cylinder. After that, read the bulk volume (unit: L) of the expanded particles from the graduations on the measuring cylinder. Then, divide the mass (unit: g) of the expanded particles in the measuring cylinder by the aforementioned bulk volume and convert the value into units to obtain the bulk density of the expanded particles (unit: kg / m 3 ) can be obtained.

[0057] After the filling step P1 is completed, a mold heating step P2 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 mold heating step P2 of this example, 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 in a state in which 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 are opened. This allows the air that has been stagnating in the internal space of the first mold 2 and the internal space of the second mold 3 to be replaced with steam, and the molding mold 1 and the expanded beads in the molding space 11 to be heated.

[0058] After the mold heating step P2 is completed, as shown in FIG. 1, a first one-side heating step P3 is carried out in which steam is supplied from the first mold 2 side to the molding space 11 to heat the foamed particles in the molding space 11. In the first one-side heating step P3 of 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 through a core vent provided in the inner wall portion 23 of the first mold 2 (see FIG. 3(b)). As a result, the foamed particles in the molding space 11 are heated. Thereafter, the steam in the molding space 11 is led to the internal space of the second mold 3 through a core vent provided in the inner wall portion 33 of the second mold 3, and is led out of the molding mold 1 from the second drain valve 32.

[0059] After the first one-sided heating step P3 is completed, as shown in FIG. 1, the second one-sided heating step P4 is carried out in which steam is supplied from the second mold 3 side to the molding space 11 to heat the foamed particles in the molding space 11. In the second one-sided heating step P4 of this example, the second steam supply valve 31 and the first drain valve 22 shown in FIG. 2 are opened, and the other valves are closed. In this state, steam is supplied from the second steam supply valve 31 to the second mold 3, 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 through a core vent provided in the inner wall portion 33 of the second mold 3 (see FIG. 3(c)). As a result, the foamed particles in the molding space 11 are heated. Thereafter, the steam in the molding space 11 is led to the internal space of the first mold 2 through a core vent provided in the inner wall portion 23 of the first mold 2, and is led out of the molding mold 1 from the first drain valve 22.

[0060] After the second one-side heating step P4 is completed, as shown in FIG. 1, a double-sided 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 the double-sided heating step P5 of this example, 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 space of the first mold 2 and the internal space of the second mold 3. The steam introduced into the internal spaces of these molds flows into the molding space 11 through the 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 Fig. 1, a retention 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 retained within the molding die 1. In the retention step P6 of this example, all of the valves 21, 22, 31, and 32 shown in Fig. 2 are closed to retain the steam within the molding die 1. This makes it possible to gradually reduce the decrease in pressure applied to the molding surface of the molding die 1 and to maintain for a long period of time the state in which the foamed beads within the molding space 11 are heated under high pressure without supplying steam to the molding die 1 (see Fig. 4).

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

[0063] After the ejection step P7 is completed, a cooling step P8 is performed 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 of spraying water onto the inner wall portions 23, 33 from the first watering nozzle 24 and the second watering nozzle 34 shown in Fig. 2, and a vacuum cooling step of reducing the pressure in the internal spaces of the first mold 2 and the second mold 3 after the water cooling step is completed.

[0064] In the water cooling step, water is sprayed onto the inner walls 23, 33 from the first water spray nozzle 24 and the second water spray nozzle 34. This makes it possible to lower the temperature of the inner walls 23, 33 and to cool the molded body in contact with the inner walls 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 is more likely to evaporate. When 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 molding die 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 manner, 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 performed 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. At this time, the molded body may be cut in advance to make it easier to break. Then, 100 or more expanded beads were randomly selected from the expanded beads exposed on the fracture surface of the molded body and visually observed to determine whether the expanded beads were broken from the inside (i.e., material destruction) or at the interface between the expanded beads (i.e., interfacial destruction). The ratio of the total number of expanded beads with material destruction to the total number of expanded beads visually observed, expressed as a percentage, was taken as the fusion rate of the molded body (unit: %). 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 the 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 facing each other in the left-right direction of the mold. The voids present in the square, i.e., the gaps formed between the foamed beads, were measured to be 0.5 mm or less in size when viewed from above. 2 The number of voids having a size of 100 mm or more was counted. The number of voids was divided by the measured area and converted to a unit area (cm 2 The number of voids per unit area was calculated. The results are shown in Table 1. The smaller 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 during in-mold molding to the time of demolding was measured. The mold was opened when the pressure (surface pressure) applied to the inner wall of the mold in the cooling process 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 Example 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 bodies with good fusion and surface conditions are manufactured while reducing the total amount of steam 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 the total amount of steam W d+f+s+b This is because the amount of steam 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 is set to a specific relationship while the amount of steam 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 is set to a specific relationship. d :W f+s+b = 5:95~40:60, and the total W with the steam volume should be f+s+b The amount of steam W when the mass percentage is 100% 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 is set to be 0.3 or more.

[0080] Comparative Example 1-1 is an example in which molding in a mold was performed under conditions that allowed a molded body with good fusion and surface conditions to be obtained without performing a holding step. In Comparative Example 1-1, a molded body 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 large. 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, the reduction rates of the total steam amount of Example 1-2, and the reduction rates of the total steam amount of 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 the two 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 holding step was performed while reducing the total amount of steam to the same extent as in Example 1-1, 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 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. f In this case, the surface condition was deteriorated.

[0084] As can be seen from a comparison between the Examples and Comparative Examples, by carrying out a holding process and ensuring that the relationship between the amounts 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 condition of the molded body.

[0085] Example 2 In this example, expanded beads with polystyrene as the base resin are used to manufacture a block-shaped molded body with a length of 800 mm, a width of 200 mm, and a height of 150 mm. Specifically, the expanded beads used in this example were obtained by expanding Styrodia (registered trademark) "XJ251N", an expandable polystyrene bead manufactured by JSP Corporation. The bulk density of the expanded beads is 17 kg / m 3The molding machine used was the "VS1300-DeCo" as in Example 1-1. The molding die was capable of molding two block-shaped bodies (volume approximately 24 L) at one molding run, 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 in the mold-in-mold molding were changed as shown in Table 2. Then, the same evaluation as in Example 1-1 was performed. 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 surface) 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, according to the manufacturing conditions of Example 2, a molded body with good fusion and surface conditions is manufactured while reducing the total amount of steam during molding in the mold, compared to the manufacturing conditions of Comparative Example 2-1, which does not include a holding step. This is thought to be because, in Example 2, the holding step is performed in the same manner as in Example 1-1, and the relationship between the amount of steam in each step is set to a specific relationship. In addition, in Example 2, a large block-shaped molded body is manufactured. Even in this case, by performing the holding step and controlling the amount of steam in each step, it is possible to obtain a molded body with good fusion and surface conditions while reducing the amount of steam used during molding in the mold.

[0091] Comparative Example 2-1 is an example in which molding in a mold was performed under conditions that allowed a molded body with good fusion and surface conditions to be obtained without performing a holding step. In Comparative Example 2-1, a molded body with good fusion and surface conditions similar to those of Example 2 was obtained, but the amount of steam used was greater. When the total steam amount of Comparative Example 2-1 was 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%. Moreover, the molding cycle in Comparative Example 2-1 was 158 seconds, whereas the molding cycle in Example 2 was 158 seconds, and the two had equivalent molding cycles.

[0092] In Comparative Example 2-2, the holding step was performed while reducing the total amount of steam to the same extent as in Example 2, 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 was deteriorated and the fusion rate of the molded body was also decreased.

[0093] Example 3 In this example, a plate-shaped molded product with a length of 910 mm, a width of 595 mm, and a thickness of 40 mm is manufactured using expanded beads containing a flame retardant and a polystyrene 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 is 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 the mold in-mold molding method in the same manner as in Example 1-1, except that the molding conditions in the mold in-mold molding were changed as shown in Table 3. Then, the same evaluation as in Example 1-1 was performed. 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 (surface of length 910 mm x width 595 mm) of the molded body.

[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, according to the manufacturing conditions of Example 3, a molded body with a good fusion state and surface condition is manufactured while reducing the total amount of steam during molding in the mold, compared to the manufacturing conditions of Comparative Example 3-1 that does not include a holding step. This is believed to be because, in Example 3, the holding step is performed in the same manner as in Examples 1-1 to 1-3 and Example 2, and the relationship between the amount of steam in each step is set to a specific relationship. In addition, in Example 3, a plate-shaped molded body different in shape from that in Example 2 is manufactured. Even in this case, by performing the holding step and controlling the amount of steam in each step, it is possible to obtain a molded body with a good fusion state and surface condition while reducing the amount of steam used during molding in the mold.

[0099] Comparative Example 3-1 is an example in which molding in a mold was performed under conditions that allowed a molded body with good fusion and surface conditions to be obtained without performing a holding step. In Comparative Example 3-1, a molded body with good fusion and surface conditions similar to those of Example 3 was obtained, but the amount of steam used was greater. When the total steam amount of Comparative Example 3-1 was 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%. Moreover, the molding cycle in Comparative Example 3-1 was 740 seconds, whereas the molding cycle in Example 3 was 735 seconds, and the two 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-way heating step P3 was fIn this case, the surface condition of the molded article was deteriorated and the fusion rate of the molded article was 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 Corporation. The bulk density of the expanded beads is 17 kg / m 3 The molding machine used was the "VS1300-MCJ" manufactured by Daisen Kogyo. The molding die can mold two of the box-shaped bodies (volume approximately 18L) at one time, and the volume (total volume) of the molding space is 36L.

[0102] In this example, a molded body was produced by the in-mold molding method in the same manner as in Example 1-1, except that the molding conditions in the 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, according to the manufacturing conditions of Example 4, compared to the manufacturing conditions of Comparative Example 4-1 that does not include a holding step, a molded body with a good fusion state and surface condition is manufactured while reducing the total amount of steam during molding in the mold. This is thought to be because, in Example 4, the holding step is performed in the same manner as in Examples 1-1 to 1-3, Examples 2, and 3, and the relationship between the amount of steam in each step is set to a specific relationship. In addition, in Example 4, a box-shaped molded body with a thicker side wall and bottom wall is manufactured 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 can be obtained while reducing the amount of steam used during molding in the mold.

[0107] Comparative Example 4-1 is an example in which molding in a mold was performed under conditions that allowed a molded body with good fusion and surface conditions to be obtained without performing a holding step. In Comparative Example 4-1, a molded body with good fusion and surface conditions similar to those of Example 1-1 was obtained, but the amount of steam used was large. In addition, 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%. Moreover, the molding cycle in Comparative Example 4-1 was 451 seconds, whereas the molding cycle in Example 4 was 456 seconds, and the two 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 was deteriorated and the fusion rate of the molded body was also decreased. [Explanation of symbols]

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

Claims

1. A method for producing an expanded bead molding, comprising the steps of: using a molding die having a first die and a second die configured to be capable of forming a molding space between the first die and the second die; and in-mold molding expanded polystyrene resin beads filled in the molding space to produce an expanded bead molding, the method comprising the steps of: The method for producing the expanded bead molded product includes a filling step of filling the molding space with expanded polystyrene resin beads, a mold heating step of supplying steam from both the first mold side and the second mold side to the molding space after the filling step, a first one-side heating step of supplying steam from the first mold side to the molding space after the mold heating step, a second one-side heating step of supplying steam from the second mold side to the molding space after the first one-side heating step, a double-sided heating step of supplying steam from both the first mold side and the second mold side to the molding space after the second one-side heating step, and a retaining step of retaining the steam supplied in the double-sided heating step in the molding space, The amount of steam in the mold heating step 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 amount of steam in the double-sided heating process W b The 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 step 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 amount of steam in the double-sided heating process W b The total amount W f+s+b The ratio is W d :W f+s+b = 5:95 to 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-sided heating step f+s+b The amount of steam W in the first one-way heating step when the amount of steam W is 100 mass% f The ratio of the steam amount W in the second one-way heating step is 15 mass% or more and 50 mass% or less. s The ratio of is 15 mass% or more and 50 mass% or less, and the steam amount W b The ratio of is 10% by mass or more and 70% by mass or less, The amount of steam W in the first one-way heating step f The amount of steam W in the double-sided heating process b Ratio of W b / W f The method for producing an expanded bead molding, wherein

2. The amount of steam W in the first one-way heating step f The method for producing an expanded molded article according to claim 1, wherein the mass of the expanded molded article 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-way heating step f The amount of steam W in the mold heating step d Ratio of W d / W f The method for producing an expanded molded article according to claim 1 or 2, wherein the m is 0.2 or more and 3 or less.

4. The amount of steam W in the first one-way 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 molded article according to claim 1 or 2, wherein the m is 0.6 or more and 2 or less.

5. The method for producing an expanded bead molding according to claim 1 or 2, wherein the holding time in the holding step is from 5 seconds to 50 seconds.

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