Apparatus and method for manufacturing foamed particles

Abstract

The purpose of the present invention is to uniformly prevent shrinkage of foamed particles at the actual machine level. In a foamed particle manufacturing device (10) according to the present invention, a curing circulation line (1) and a drying hot air line (2) are configured so as to take in a curing gas (A) and drying hot air (B) from a lower section of a dryer (3), said curing gas (A) including steam, outside air, and the atmosphere of an upper section of the dryer (3), and a blowing outlet (5) is configured so as to discharge the curing gas (A) and the drying hot air (B) from the upper section of the dryer (3).

Description

Technical Field

[0001] The present invention relates to an apparatus and a method for manufacturing foamed particles.

Background Art

[0002] Foamed particles made of a thermoplastic resin are produced by a method (hereinafter referred to as the pressure-release foaming method) in which thermoplastic resin particles are dispersed in water containing a dispersant in a pressure-resistant container, then a volatile foaming agent is added, and after being impregnated with the volatile foaming agent while maintained under high temperature and high pressure, it is released into a low-pressure atmosphere. As a method for manufacturing foamed particles by the pressure-release foaming method, for example, there is the technique described in Patent Document 1.

[0003] FIG. 3 is a diagram schematically showing the schematic configuration of the apparatus for manufacturing foamed particles disclosed in Patent Document 1. As shown in FIG. 3, the apparatus for manufacturing foamed particles disclosed in Patent Document 1 includes a pressure-resistant container 303, a valve 304, an orifice 305, a low-pressure container 306, a transport medium supply unit 311, a drying intake blower 318, and an air heater 319. In the pressure-resistant container 303, resin particles 301 made of a polyolefin-based resin composition are dispersed in an aqueous dispersion medium 302. In the pressure-resistant container 301, the resin particles 301 are heated to a temperature equal to or higher than the softening temperature of the resin particles 301, and after becoming water-containing resin particles, they are foamed by being released into a low-pressure container 306 having a lower internal pressure than the internal pressure of the pressure-resistant container 301. When the valve 304 is opened, the resin particles 301 pass through the orifice 305 and are released into the low-pressure container 306 (released particles 307).

[0004] Saturated steam is injected into the low-pressure vessel 306 from the steam inlet 308, and the released particles 307, which are foamed particles, come into contact with the saturated steam. The released particles 307 and the dispersion medium 310 are separated in the filtration section 312. The dispersion medium 310 is discharged from the outlet 309. The released particles 307, along with the transport medium 314 supplied from the transport medium supply section 311, are transported through the outlet 313 of the low-pressure vessel 306 to the dryer 315. The transport medium 314 is saturated steam. The line through which the released particles 307 are transported from the pressure vessel 303 through the low-pressure vessel 306 to the dryer 315 constitutes part of the depressurization foaming circulation line (described later).

[0005] In this manner, the released particles 307 come into contact with saturated water vapor and are then transported to the dryer 315. After the released particles 307 are transported to the dryer 315, the depressurization foam circulation line is closed. Subsequently, nitrogen gas is introduced into the dryer 315 from the N2 inlet 316, adjusting the flow rate while measuring the temperature inside the dryer 315 with a temperature recorder 317, and the temperature inside the dryer 315 is lowered to the drying temperature over a period of 5 minutes or more. After the temperature inside the dryer 315 has been lowered to the drying temperature in this way, hot air at the drying temperature is introduced into the dryer 315 through the drying air blower 318 and the air heater 319 to dry the foamed particles.

[0006] In the technology described in Patent Document 1, foam particles released from the pressure vessel 303 are brought into contact with saturated water vapor, then cooled to a drying temperature over a period of 5 minutes or more, before proceeding to the drying process. This prevents and reduces shrinkage of the foam particles. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2000-290420 [Overview of the project] [Problems that the invention aims to solve]

[0008] The technology described in Patent Document 1 prevents and reduces shrinkage of foamed particles by performing a curing process in which nitrogen gas is passed through the foamed particles after depressurization foaming to gradually lower the temperature of the foamed particles to the drying temperature. However, the technology described in Patent Document 1 has room for improvement in the following respects. Specifically, it has been found that even when the technology described in Patent Document 1 is applied to equipment at the actual machine level, it is not possible to uniformly prevent shrinkage of the foamed particles, and variations in the bulk density of the foamed particles may occur. As a result, the molded product of the foam has large weight variations, and the quality such as surface properties and compressive strength deteriorates.

[0009] One aspect of the present invention aims to realize a foam particle manufacturing apparatus and manufacturing method that can uniformly prevent the shrinkage of foam particles at a real-world level. [Means for solving the problem]

[0010] To solve the above problems, an apparatus for producing foamed particles according to one aspect of the present invention includes a dryer for drying foamed particles, (a) having a first outside air intake port for taking in outside air and a dryer atmosphere intake port for taking in the atmosphere above the dryer, (b) a curing circulation line that passes a curing gas containing outside air taken in from the first outside air intake port and the atmosphere above the dryer taken in from the dryer atmosphere intake port to the dryer, (c) having a second outside air intake port for taking in outside air and a heater, and (d) the drying A foam particle manufacturing apparatus comprising a container, a drying hot air line that passes outside air taken in from the second outside air intake port through the heater to produce drying hot air, and an air outlet that discharges the curing gas and the drying hot air to the outside, wherein the curing circulation line and the drying hot air line are configured to take in the curing gas and the drying hot air from the bottom of the dryer, and the air outlet is configured to discharge the curing gas and the drying hot air from the top of the dryer.

[0011] To solve the above problems, a method for producing foamed particles according to one aspect of the present invention includes a curing step in which a curing circulation line is installed in a dryer for drying the foamed particles after foaming, through which a curing gas including outside air and the atmosphere above the dryer is passed, and the amount of outside air taken into the curing circulation line is adjusted to gradually lower the temperature of the foamed particles from the temperature immediately after foaming; and a drying step in which a drying hot air line is installed in the dryer for passing drying hot air, and the foamed particles after the curing step are dried with the drying hot air, and the method includes a curing preparation step in which the temperature and water vapor pressure of the curing circulation line are adjusted in advance to match the temperature and water vapor pressure at the start of curing. [Effects of the Invention]

[0012] According to one aspect of the present invention, it is possible to uniformly prevent the shrinkage of foam particles at the actual machine level. [Brief explanation of the drawing]

[0013] [Figure 1] This figure schematically shows the general configuration of a foam particle manufacturing apparatus according to an embodiment of the present invention. [Figure 2] This diagram schematically shows the general configuration of a conventional foam particle manufacturing apparatus. [Figure 3] This diagram schematically shows the general configuration of the foam particle manufacturing apparatus disclosed in Patent Document 1. [Modes for carrying out the invention]

[0014] [Technical concept of the present invention: Regarding the curing process] The curing process for foamed particles involves drawing in outside air into a dryer containing the foamed particles and replacing the water vapor in the particles with air. This curing process helps to suppress the shrinkage of the foamed particles.

[0015] Immediately after foaming in a steam atmosphere using the depressurization foaming method, the foamed particles are stored in a dryer. When these immediately foamed particles are subjected to a drying process by blowing hot drying air into them, the foamed particles are exposed to an environment where the temperature drops rapidly, causing the water vapor within the particles to condense. As a result, the foamed particles shrink.

[0016] Therefore, in the curing process, air from the outside is gradually drawn into the dryer where the foamed particles are stored immediately after foaming, gradually lowering the temperature of the foamed particles and preventing shrinkage. In addition, lowering the temperature of the foamed particles also has the effect of suppressing shrinkage of the foamed particles by hardening the constituent resin.

[0017] In the curing process, in order to prevent the foam particles from shrinking, it is necessary to control the following (A) and (B): (A) the state in which the constituent resin of the foam particles cools and hardens, and (B) the state in which the condensation of water vapor caused by the rapid temperature drop due to the inflow of air into the foam particles is mitigated.

[0018] The state described in (A) above is controlled by the temperature of the foam particles, and the state described in (B) above is controlled by the amount of air in the foam particles. Here, in foam particles, under normal pressure, when water vapor cools, air is always present (flows in), so there is a correlation between temperature and the amount of air.

[0019] Therefore, (A) and (B) above can be adjusted by a single factor: the temperature of the foam particles (corresponding to the amount of air). Furthermore, the curing process can be controlled by controlling two factors: the rate at which the temperature of the foam particles decreases (corresponding to the air inflow rate) and the temperature reached during curing (corresponding to the total amount of air inflow). The above represents a novel finding by the inventors.

[0020] In the manufacturing apparatus disclosed in Patent Document 1, although the above-described curing process can be performed, there is still room for improvement in preventing the shrinkage of the expanded particles evenly at the actual machine level. In view of such a situation, the inventors of the present invention have conducted intensive studies and as a result, have completed the present invention, with the aim of providing a manufacturing apparatus that can prevent the shrinkage of expanded particles uniformly with respect to an actual machine used for actual expanded particle production.

[0021] 〔Configuration of the manufacturing apparatus for expanded particles according to the present embodiment〕 Hereinafter, an embodiment of the present invention will be described in detail. FIG. 1 is a diagram schematically showing the schematic configuration of a manufacturing apparatus 10 for expanded particles according to the present embodiment.

[0022] As shown in FIG. 1, the manufacturing apparatus 10 includes a depressurization foaming circulation line J, a curing circulation line 1, a drying hot air line 2, a dryer 3 for drying the expanded particles, and a blower S. In the manufacturing apparatus 10 according to the present embodiment, the undried expanded particles transported in the depressurization foaming circulation line J are introduced into the dryer 3. The expanded particles are cured and dried in the dryer 3. Further, the blower S sends the gas flowing in the curing circulation line 1 and the drying hot air line 2 to the dryer 3.

[0023] The depressurization foaming circulation line J is a transport line for transporting expanded particles produced by the depressurization foaming method. The depressurization foaming circulation line J is configured to take in steam from the outside and circulate the transport medium of the expanded particles. The depressurization foaming circulation line J is not particularly limited as long as it has a configuration in which equipment capable of realizing foaming by the depressurization foaming method is pipe-connected. For example, the depressurization foaming circulation line J is a circulation line to which a pressure-resistant container for storing resin particles or the like as a raw material of the expanded particles, a low-pressure container (for example, a foaming cylinder) that constitutes a space for discharging the resin particles impregnated with the foaming agent from the pressure-resistant container, a dehydrator, a dryer, and the like are connected. Such a depressurization foaming circulation line J is shown in, for example, FIGS. 6 and 7 of International Publication WO2020 / 158061.

[0024] Curing circulation line 1 is a line for adjusting the curing process of foamed particles inside the dryer 3. Curing circulation line 1 is a piping line provided independently of the depressurization foaming circulation line J. Curing circulation line 1 is configured to take in outside air and steam from the outside.

[0025] The curing circulation line 1 includes a curing outside air intake 1a (first outside air intake), an outside air control valve 1b, a curing thermometer 1c (first thermometer), an on-off valve 1d, a circulation flow rate control valve 1e, a dryer atmosphere intake 1f, a curing steam intake 4a, and an on-off valve 4b. The curing steam intake 4a is provided to take in curing steam into the curing circulation line 1. The dryer atmosphere intake 1f is provided to take in the atmosphere from the top of the dryer 3. The curing circulation line 1 passes gas A (curing gas), which includes outside air taken in from the outside air intake 1a and the atmosphere from the top of the dryer 3 taken in from the dryer atmosphere intake 1f, through to the dryer 3. The outside air control valve 1b is a valve that adjusts the amount of outside air taken in from the outside air intake 1a. The thermometer 1c measures the temperature of the foam particles inside the dryer 3. The reading from the thermometer 1c is transmitted to the outside air control valve 1b. The outside air control valve 1b then controls the valve opening based on the comparison between the reading from the thermometer 1c and a predetermined temperature set value for the foam particles, thereby adjusting the amount of outside air taken in from the outside air intake port 1a. The on-off valve 1d is a valve that switches the opening and closing of the inflow of gas A into the dryer 3. The circulation flow rate control valve 1e is a valve that adjusts the flow rate of gas A. In the curing circulation line 1, the blower S causes gas A to pass through the dryer 3. In the manufacturing apparatus 10, when the foam particles in the dryer 3 are curing, the on-off valve 1d is open, allowing gas A to pass through the dryer 3. On the other hand, when the foam particles are not curing (for example, during drying), the on-off valve 1d is closed, preventing gas A from flowing into the dryer 3.

[0026] The drying hot air line 2 includes an outside air intake 2a (second outside air intake) for drying, a heater 2b, an on-off valve 2c, and a drying thermometer 2d (second thermometer). A steam volume control valve 2e is also provided at the steam intake of the heater 2b. In the drying hot air line 2, outside air is drawn in through the outside air intake 2a by opening the on-off valve 2c, and this outside air is passed through the heater 2b to generate drying hot air B. The drying hot air line 2 then passes this generated drying hot air B to the dryer 3. The thermometer 2d measures the temperature at the top of the dryer 3. The valve opening of the steam volume control valve 2e is controlled according to the measurement from the thermometer 2d. This adjusts the temperature of the drying hot air B flowing to the dryer 3.

[0027] In the drying hot air line 2, the blower S causes the drying hot air B to pass through the dryer 3. When the foamed particles are being dried, the on-off valve 1d of the curing circulation line 1 closes and the on-off valve 2c opens, allowing the drying hot air B to pass through the dryer 3. At this time, the on-off valve 4b for steam intake in the curing circulation line 1 is closed. On the other hand, when the foamed particles are not being dried (for example, during curing), the on-off valve 2c is closed, preventing the drying hot air B from flowing into the dryer 3.

[0028] The dryer 3 can employ a conventionally known configuration used for drying foamed particles. In the configuration shown in Figure 1, the lower part of the dryer 3 has a conical outer casing 31, and the outer casing 31 is equipped with an opening plate 3e through which gas passes. The shape of the outer casing 31 is not particularly limited and may be a polyhedral pyramidal shape. Preferably, the outer casing 31 is conical.

[0029] As shown in Figure 1, the dryer 3 comprises a main body 3a which contains foamed particles, a plurality of gas inlets 3b, a plurality of flow control valves 3c, an outer casing 31, and an opening plate 3e. The outer casing 31 comprises a plurality of stepped sections 3d and an opening plate 3e. The gas inlets 3b are inlets for introducing gas A and drying hot air B into the main body 3a. The flow control valves 3c are provided to correspond to the gas inlets 3b. In addition, each stepped section 3d is provided to correspond to the gas inlets 3b and the flow control valves 3c. In the dryer 3, both the inlet for introducing gas A and the inlet for introducing drying hot air B into the main body 3a are shared by the gas inlet 3b. However, the configuration is not limited to this, and the gas inlets may be configured such that the inlets for introducing gas A and the inlets for introducing drying hot air B are separate.

[0030] Furthermore, each stepped portion 3d constitutes a jacket portion that covers the outer circumference of the conical portion at the bottom of the main body 3a. Each stepped portion 3d has a space for retaining the gas introduced from the gas inlet 3b corresponding to that stepped portion 3d. The opening plate 3e has an opening that connects this space to the inside of the main body 3a. The form of this opening is not particularly limited, and for example, a wire mesh, perforated metal, or slits can be used.

[0031] The flow rate of gas entering the main body 3a from each gas inlet 3b can be set for each of the multiple stages 3d by adjusting the opening degree or switching the opening / closing of each flow control valve 3c. This allows the manufacturing apparatus 10 to regulate the amount of gas introduced into the main body 3a of the dryer 3. Therefore, the gas flow rate introduced into the main body 3a of the dryer 3 can be controlled more precisely. This allows for more uniform control of the curing process for the foamed particles contained in the dryer 3.

[0032] As shown in Figure 1, the manufacturing apparatus 10 according to this embodiment is equipped with an air outlet 5 for discharging gas A and drying hot air B to the outside. The curing circulation line 1 and the drying hot air line 2 are configured to take in gas A and drying hot air B from the entire circumference of the lower part of the main body 3a of the dryer 3. The air outlet 5 is located at the top of the dryer 3 and is configured to discharge gas A and drying hot air B from the top of the main body 3a of the dryer 3. Therefore, during the curing process, gas A can be brought into even contact with the foam particles contained in the dryer 3. Similarly, during the drying process, drying hot air B can be brought into even contact with the foam particles contained in the dryer 3. Furthermore, the above configuration does not depend on the dimensions of the dryer 3 and will have the same effect even for a full-scale manufacturing apparatus 10. In addition, according to the configuration of the manufacturing apparatus 10, the drying hot air line 2 can take in outside air from the outside air intake port 2a and control the temperature inside the dryer 3 according to a set value. Therefore, in the curing process, it is possible to uniformly prevent shrinkage of the foamed particles compared to the actual machine used for manufacturing the foamed particles.

[0033] Furthermore, the manufacturing apparatus 10 can uniformly prevent shrinkage of the foam particles, thereby suppressing variations in the bulk density of the foam particles. Moreover, the molded articles formed using these foam particles have reduced weight variations and improved quality in terms of surface properties and compressive strength.

[0034] Furthermore, the manufacturing apparatus 10 allows for even contact between the foam particles and the drying hot air B, thereby shortening the curing time and drying time. Therefore, the manufacturing of foam particles can be made more efficient, and the energy and costs associated with this manufacturing process can be reduced.

[0035] Figure 2 is a schematic diagram showing the general configuration of a conventional foam particle manufacturing apparatus 20. In the manufacturing apparatus 20, the drying hot air line 22 is configured to take in outside air for curing and outside air for drying. In the drying hot air line 22, outside air for curing is introduced into the dryer 23 from the outside air intake port 22a by a blower S1. The amount of outside air for curing is controlled by switching the on / off valve 22b and adjusting the opening degree of the control valve 22c. The manufacturing apparatus 20 may also be provided with an outside air intake port 22d for curing as needed. Outside air for curing is introduced into the dryer 23 by a blower S2. The flow rate of outside air for curing is controlled by switching the on / off valve 22f and adjusting the opening degree of the control valve 22e. The outside air for curing is configured to come into local contact with the foam particles contained in the dryer 23.

[0036] Furthermore, outside air for drying is drawn in through the outside air intake 22g by opening the on / off valve 22i. The drawn-in outside air is then heated by the heater 22h to become drying hot air. This drying hot air is then introduced into the dryer 23 by the blower S1. The temperature of the drying hot air is controlled by the steam volume control valve 22k. The drying hot air is configured to come into local contact with the foam particles contained in the dryer 23. The thermometer 22j measures the temperature at the top of the dryer 23. The opening of the steam volume control valve 22k is controlled according to the measurement taken by the thermometer 22j. This adjusts the temperature of the drying hot air flowing into the dryer 23.

[0037] Thus, in the conventional manufacturing apparatus 20, the foam particles come into localized contact with the curing outside air and the drying hot air. In this configuration, as the dimensions of the dryer 23 increase, it becomes difficult to evenly expose the foam particles contained in the dryer 23 to the curing gas and drying hot air. Therefore, in the conventional manufacturing apparatus 20, when used at the actual machine level, it is not possible to uniformly prevent shrinkage and dry the foam particles during the curing and drying processes. As a result, variations in the bulk density and drying of the foam particles occur.

[0038] (Method for manufacturing foamed particles) The method for manufacturing foamed particles according to this embodiment includes a curing step and a drying step. In the curing step, a curing circulation line is installed to pass a curing gas, including outside air and the atmosphere above the dryer, through a dryer for drying the foamed particles after foaming. By adjusting the amount of outside air flowing through the curing circulation line, the temperature of the foamed particles is gradually lowered from the temperature immediately after foaming. In the drying step, a drying hot air line is installed to pass drying hot air through the dryer, and the foamed particles after the curing step are dried with the drying hot air. The method for manufacturing foamed particles according to this embodiment is characterized by including a curing preparation step before the curing step. In the curing preparation step, the temperature and water vapor pressure of the curing circulation line are adjusted in advance to the temperature and water vapor pressure at the start of curing. The curing preparation step is a step of preheating the curing circulation line. In the curing preparation step, the curing circulation line is preheated by taking in steam. The timing of the curing preparation step is not particularly limited as long as it is before the curing step. For example, the curing preparation step may be performed before the foaming of resin particles by the depressurization foaming method. In this case, the temperature and water vapor pressure at the start of curing will be the same as the temperature and water vapor pressure after foaming is completed. Furthermore, in the method for manufacturing foamed particles according to this embodiment, in addition to the curing preparation step, a depressurization foaming preparation step may be performed to preheat the depressurization foaming circulation line. The curing preparation step and the depressurization foaming preparation step may be performed simultaneously. That is, when performing the curing preparation step, the depressurization foaming circulation line may be preheated in addition to the curing circulation line. Alternatively, the curing preparation step and the depressurization foaming preparation step may be performed separately.

[0039] The following describes a method for producing foamed particles according to this embodiment, in which the curing preparation step, the foaming step of resin particles by the depressurization foaming method, the curing step, and the drying step are carried out in that order. However, the method for producing foamed particles according to this embodiment is not limited to this order.

[0040] Furthermore, the method for manufacturing foamed particles according to this embodiment is not particularly limited as long as it can carry out the curing step, the drying step, and the curing preparation step. For example, one method for manufacturing foamed particles according to this embodiment is the method using the manufacturing apparatus 10 shown in Figure 1. Below, the method for manufacturing foamed particles according to this embodiment using the manufacturing apparatus 10 shown in Figure 1 will be described. In the following, an example in which the curing preparation step and the depressurization foaming preparation step are carried out simultaneously (hereinafter, this step may be referred to as the foaming and curing preparation step) will be described.

[0041] (Foaming and curing preparation process) The foaming and curing preparation process is carried out before starting the foaming process of the resin particles. In the curing preparation process, the temperature and water vapor pressure of the curing circulation line 1 are set in advance to be the same as the temperature and water vapor pressure at the start of curing (i.e., the temperature after foaming is completed).

[0042] In the foaming and curing preparation process, the on-off valve 1d of the curing circulation line 1 is opened. Also, the on-off valve 4b of the curing steam intake port 4a of the curing circulation line 1 is opened, allowing steam to be drawn in from the curing steam intake port 4a into the curing circulation line 1 and circulated within the curing circulation line 1. Furthermore, all of the multiple flow control valves 3c are opened to allow steam to flow into the main body 3a. In addition, the outside air control valve 1b is closed to prevent outside air from being drawn in through the outside air intake port 1a.

[0043] Furthermore, in the foaming and curing preparation process, steam is circulated not only in the curing circulation line but also in the depressurizing foaming circulation line J. At this time, the on / off valve (not shown) of the steam intake port (not shown) of the depressurizing foaming circulation line J is opened, and steam is drawn into the depressurizing foaming circulation line J from this steam intake port. The steam drawn into the depressurizing foaming circulation line J flows into the main body 3a from the inlet of the undried foamed particles.

[0044] In this way, during the foaming and curing preparation process, steam is circulated through both the depressurization foaming circulation line J and the curing circulation line 1. Steam is then introduced into the main body 3a of the dryer 3 from both the depressurization foaming circulation line J and the curing circulation line 1. When the temperature and water vapor pressure within the system, including the depressurization foaming circulation line J, the curing circulation line 1, and the dryer 3, become the same as the temperature and water vapor pressure at the start of curing (i.e., the temperature at the end of foaming) and the start of foaming, steam intake is stopped, and the curing preparation process is completed. Then, the process proceeds to the next step, the foaming process. The target temperature at the start of curing is approximately 95±5℃.

[0045] If a foaming and curing preparation process is not performed to preheat the curing circulation line 1, untemperature-controlled cold air from the curing circulation line 1 will flow into the dryer 3 at the start of curing. As a result, the foam particles near the gas inlet in the main body 3a of the dryer 3 will be rapidly cooled and will shrink. Furthermore, the water vapor inside the main body 3a will condense, and outside air will be drawn in from the air outlet of the dryer 3, causing the temperature of the foam particles to drop. Consequently, shrinkage of the foam particles will occur.

[0046] Furthermore, if the temperature of the curing circulation line 1 is lower than the curing start temperature (e.g., 95±5℃) when the curing process is started, additional steam is introduced into the curing circulation line 1. Then, the temperature of the curing circulation line 1 is raised so that it approaches the curing start temperature in the dryer 3, and then the curing process is started.

[0047] The foaming and curing preparation process should be carried out before the start of depressurization foaming, ensuring that the temperature inside the dryer 3 and the temperature inside the curing circulation line 1 are the same. Preferably, the temperature inside the dryer 3 and the temperature inside the curing circulation line 1 should be set to 95±5℃.

[0048] (Curing process) A foaming process is carried out prior to the curing process. Any known foaming technique can be applied to the foaming process, provided it is a depressurization foaming method. In the curing process, the undried foamed particles immediately after foaming are placed in the main body 3a of the dryer 3. By adjusting the amount of outside air flowing through the curing circulation line 1, the temperature of the foamed particles is gradually reduced from the temperature immediately after foaming.

[0049] In the curing process, the curing circulation line 1 is configured to take in outside air from the outside air intake 1a, as well as the steam atmosphere above the dryer 3, and gas A, which includes the outside air and the atmosphere above the dryer 3, is passed through the dryer 3. As a result, gas A comes into contact with the foam particles inside the dryer 3.

[0050] Then, according to the predetermined temperature setting conditions for the foamed particles during the curing process, the temperature of the foamed particles in the dryer 3 is gradually reduced from the temperature immediately after foaming. Based on the comparison result between the temperature setting value of the foamed particles during the curing process and the measurement value of the thermometer 1c during the curing process, the valve opening of the outside air control valve 1b is controlled to adjust the amount of outside air taken in from the outside air intake port 1a. By adjusting the amount of outside air taken in from the outside air intake port 1a in this way and mixing the taken-in outside air with the atmosphere at the top of the dryer 3, the temperature of the foamed particles in the dryer 3 can be gradually reduced with precision.

[0051] The temperature setting conditions for the foamed particles in the curing process are not particularly limited and can be set as appropriate depending on the configuration of the manufacturing apparatus 10 and the desired characteristics of the foamed particles. Preferably, in the curing process, the curing start temperature is set to 95±5℃ and the temperature of the foamed particles is lowered to 85±5℃.

[0052] Furthermore, if the temperature decrease rate of the foam particles during the curing process is too high, the temperature will drop too rapidly, causing the foam particles to shrink. On the other hand, if the temperature decrease rate is too low, the production efficiency of the foam particles will deteriorate. From this viewpoint, the temperature decrease rate of the foam particles during the curing process is preferably -1.5°C / min or more and less than 0°C / min, and more preferably -0.7°C / min. In addition, the temperature decrease time is preferably 20 ± 10 minutes.

[0053] (drying process) In the drying process, the foamed particles are dried by passing the drying hot air B through the drying hot air line 2 to the dryer 3.

[0054] In the drying process, first, the on / off valve 1d of the curing circulation line 1 is closed. Then, outside air is taken in from the outside air intake port 2a of the drying hot air line 2, and the outside air is passed through the heater 2b to generate drying hot air B. Then, the drying hot air B is passed through the dryer 3. The temperature of the drying hot air B is adjusted by adjusting the valve opening of the steam amount adjustment valve 2e according to the measurement value of the thermometer 2d. The temperature of the drying hot air B is adjusted in accordance with the drying conditions of the foamed particles in the drying process. The drying conditions of the foamed particles in the drying process are not particularly limited and can be set as appropriate according to the characteristics of the foamed particles and the configuration of the manufacturing apparatus 10.

[0055] (Regarding foaming particles) In this embodiment, the raw materials for the foamed particles used may be any raw materials that can be foamed by the pressure-relieving foaming method described above, and include at least a crystalline thermoplastic resin and a foaming agent. In addition to the crystalline thermoplastic resin and foaming agent, various additives may be added as necessary to the raw materials for the foamed particles. Examples include flame retardants, heat stabilizers, radical generators, processing aids, weather-resistant stabilizers, nucleating agents, foaming aids, antistatic agents, radiative heat transfer inhibitors, and colorants. These additives can be used individually or in combination of two or more.

[0056] The thermoplastic resin used in this embodiment is not particularly limited as long as it is a generally known crystalline thermoplastic resin having foaming properties. Examples of the thermoplastic resin include polyolefin resins, polyester resins, polyphenylene ether resins, polyamide resins, and mixtures thereof. The thermoplastic resin is preferably a polyolefin resin or a polyester resin.

[0057] Examples of polyester resins include aliphatic polyester resins, aromatic polyester resins, and aliphatic aromatic polyester resins. Specific examples of polyester resins include polyhydroxyalkanoates, polybutylene succinates (PBS), poly(butylene adipate-co-butylene terephthalate) (PBAT), and polyethylene terephthalate (PET). Furthermore, polyhydroxyalkanoates are at least one selected from the group consisting of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), poly(3-hydroxybutyrate) (P3HB), poly(3-hydroxybutyrate-co-3-hydroxyvalate) (PHBV), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), and poly(3-hydroxybutyrate-co-3-hydroxyoctadecanoate).

[0058] Furthermore, the polyolefin resin is not particularly limited, and examples include the polyolefin resins exemplified in International Publication WO2020 / 158061.

[0059] [Method for manufacturing molded bodies of foamed particles] The method for manufacturing a molded article of foamed particles according to this embodiment is a method for molding foamed particles obtained by the manufacturing method described above. To manufacture a molded article of foamed particles, the foamed particles can be molded by known methods.

[0060] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining each of the technical means disclosed in the embodiments are also included in the technical scope of the present invention.

[0061] 〔summary〕 The foam particle manufacturing apparatus 10 according to Embodiment 1 of the present invention comprises a dryer 3 for drying foam particles, (a) a first outside air intake port (outside air intake port 1a) for taking in outside air and a dryer atmosphere intake port 1f for taking in the atmosphere above the dryer 3, (b) a curing circulation line 1 that passes a curing gas (gas A) containing outside air taken in from the first outside air intake port and the atmosphere above the dryer 3 taken in from the dryer atmosphere intake port 1f to the dryer 3, and (c) a second outside air intake port (outside air intake port 2a) for taking in outside air and a heater 2b (d) A foam particle manufacturing apparatus 10 comprising: a drying hot air line 2 that passes drying hot air B, obtained by passing outside air taken in from the second outside air intake port through the heater 2b, to the dryer 3; and an air outlet 5 that discharges the curing gas and the drying hot air B to the outside, wherein the curing circulation line 1 and the drying hot air line 2 are configured to take in the curing gas and the drying hot air B from the bottom of the dryer 3, and the air outlet 5 is configured to discharge the curing gas and the drying hot air B from the top of the dryer 3.

[0062] The foam particle manufacturing apparatus 10 according to embodiment 2 of the present invention, in embodiment 1, is provided with a plurality of gas inlets 3b at the lower part of the dryer 3 for introducing the curing gas (gas A) and the drying hot air B, and is configured to adjust the gas flow rate introduced into the dryer 3 by changing the valve opening of the gas inlets 3b.

[0063] In the foam particle manufacturing apparatus 10 according to embodiment 3 of the present invention, in embodiment 1 or 2, the lower part of the dryer 3 has an outer casing 31, and the outer casing 31 is configured to have an opening plate 3e through which gas passes.

[0064] In any of embodiments 1 to 3, the foam particle manufacturing apparatus 10 according to embodiment 4 of the present invention is configured such that the curing circulation line 1 further has a steam intake port (curing steam intake port 4a) for taking in steam.

[0065] The foam particle manufacturing apparatus 10 according to embodiment 5 of the present invention is configured such that, in any of embodiments 1 to 4, the foam particles are polyolefin resin foam particles.

[0066] The foam particle manufacturing apparatus 10 according to embodiment 6 of the present invention, in any of embodiments 1 to 5, comprises an outside air control valve 1b for adjusting the amount of outside air taken in from the first outside air intake (outside air intake 1a), and a first thermometer (thermometer 1c) for measuring the temperature of the foam particles in the dryer 3, wherein the outside air control valve 1b adjusts the amount of outside air taken in from the first outside air intake by controlling the valve opening based on the result of comparing the measurement value of the first thermometer with the temperature set value of the foam particles.

[0067] The foam particle manufacturing apparatus 10 according to embodiment 7 of the present invention, in any of embodiments 1 to 6, comprises a steam volume control valve 2e provided at the steam intake of the heater 2b and a second thermometer (thermometer 2d) for measuring the temperature of the upper part of the dryer 3, and the temperature of the drying hot air B flowing to the dryer 3 is adjusted by controlling the valve opening of the steam volume control valve 2e according to the measurement value of the second thermometer.

[0068] A method for producing foamed particles according to aspect 8 of the present invention includes a curing step in which a curing circulation line 1 is installed in a dryer 3 for drying the foamed particles after foaming, through which a curing gas (gas A) including outside air and the atmosphere above the dryer 3 is passed, and the amount of outside air taken into the curing circulation line 1 is adjusted to gradually lower the temperature of the foamed particles from the temperature immediately after foaming; and a drying step in which a drying hot air line 2 is installed in the dryer 3 through which drying hot air B is passed, and the foamed particles after the curing step are dried with the drying hot air B, and the method includes a curing preparation step in which the temperature and water vapor pressure of the curing circulation line 1 are adjusted in advance to match the temperature and water vapor pressure at the start of curing.

[0069] The method for producing foamed particles according to aspect 9 of the present invention is, in aspect 8, a method in which the curing step is performed in which the curing start temperature is set to 95±5℃, and the temperature of the foamed particles is lowered to 85±5℃ at a temperature decrease rate of -1.5℃ / min or more and less than 0℃ / min.

[0070] A method for producing foamed particles according to embodiment 10 of the present invention is a method in which, in embodiment 8 or 9, steam is taken into the curing circulation line 1 and the steam is circulated within the curing circulation line 1 during the curing preparation step.

[0071] A method for producing foamed particles according to embodiment 11 of the present invention, in any of embodiments 8 to 10, wherein the curing circulation line 1 comprises a first outside air intake port (outside air intake port 1a) for taking in outside air, an outside air control valve 1b for adjusting the amount of outside air taken in from the first outside air intake port, and a first thermometer (thermometer 1c) for measuring the temperature of the foamed particles in the dryer 3, and in the curing process, the amount of outside air taken in from the first outside air intake port is adjusted by controlling the valve opening of the outside air control valve 1b based on the result of comparing the temperature set value of the foamed particles during the curing process with the measurement value of the first thermometer during the curing process.

[0072] A method for producing foamed particles according to embodiment 12 of the present invention is a method in which, in any of embodiments 8 to 11, the drying hot air line 2 comprises a heater 2b, a steam volume control valve 2e provided at the steam intake of the heater 2b, and a second thermometer (thermometer 2d) for measuring the temperature of the upper part inside the dryer 3, and in the drying process, the temperature of the drying hot air is adjusted by adjusting the valve opening of the steam volume control valve 2e according to the measurement value of the second thermometer.

[0073] A method for producing foamed particles according to aspect 13 of the present invention is a method in which, in any of aspects 8 to 12, the foamed particles are polyolefin resin foamed particles.

[0074] The method for manufacturing a molded article of foamed particles according to aspect 13 of the present invention is a method for molding foamed particles obtained by any of the foamed particle manufacturing methods of aspects 8 to 12. [Explanation of Symbols]

[0075] 1. Curing and circulation line 1a Outdoor air intake (first outdoor air intake) 1b Outdoor air control valve 1c Thermometer (First thermometer) 1F Dryer atmosphere intake 2. Drying hot air line 2a. Outside air intake (second outside air intake) 2b Heater 2D thermometer (second thermometer) 2e Steam volume control valve 3 Dryer 31 Mantle 3b Gas inlet 3e opening plate 4a Curing steam intake (steam intake) 5 Air outlet A. Gas (Curing gas) B Dry hot air

Claims

1. A dryer for drying foam particles, (a) Having a first outside air intake for taking in outside air and a dryer atmosphere intake for taking in the atmosphere above the dryer, (b) A curing circulation line that passes a curing gas including outside air taken in from the first outside air intake and the atmosphere above the dryer taken in from the dryer atmosphere intake to the dryer, (c) Having a second outside air intake port and a heater for taking in outside air, (d) A drying hot air line that passes the outside air taken in from the second outside air intake port through the heater to the dryer, and brings the drying hot air into contact with the foam particles contained in the dryer, An air outlet for discharging the curing gas and the drying hot air to the outside, A device for producing foamed particles, comprising: A foam particle manufacturing apparatus, wherein the curing circulation line and the drying hot air line are configured to take in the curing gas and the drying hot air from the bottom of the dryer, and the air outlet is configured to discharge the curing gas and the drying hot air from the top of the dryer.

2. The lower part of the dryer is provided with multiple gas inlets for introducing the curing gas and the drying hot air. The apparatus for producing foamed particles according to claim 1, wherein the flow rate of gas introduced into the dryer is adjusted by changing the valve opening of the gas inlet.

3. The apparatus for producing foamed particles according to claim 1 or 2, wherein the lower part of the dryer has an outer casing, and the outer casing is provided with an opening plate through which gas passes.

4. The apparatus for producing foamed particles according to any one of claims 1 to 3, wherein the curing circulation line further has a steam intake port for taking in steam.

5. A dryer for drying foamed particles, (a) Having a first outside air intake for taking in outside air and a dryer atmosphere intake for taking in the atmosphere above the dryer, (b) A curing circulation line that passes a curing gas including outside air taken in from the first outside air intake and the atmosphere above the dryer taken in from the dryer atmosphere intake to the dryer, (c) Having a second outside air intake port and a heater for taking in outside air, (d) A drying hot air line that passes the outside air taken in from the second outside air intake port through the heater to the dryer, An air outlet for discharging the curing gas and the drying hot air to the outside, A device for producing foamed particles, comprising: The curing circulation line and the drying hot air line are configured to take in the curing gas and the drying hot air from the bottom of the dryer, respectively, and the air outlet is configured to discharge the curing gas and the drying hot air from the top of the dryer. The curing circulation line further includes a steam intake port for taking in steam, and is a device for producing foamed particles.

6. The apparatus for producing foamed particles according to any one of claims 1 to 5, wherein the foamed particles are polyolefin resin foamed particles.

7. The aforementioned curing circulation line is, An outside air control valve that adjusts the amount of outside air taken in from the first outside air intake, The oven is equipped with a first thermometer for measuring the temperature of the foam particles inside the oven, The apparatus for producing foamed particles according to any one of claims 1 to 6, wherein the outside air control valve adjusts the amount of outside air taken in from the first outside air intake by controlling the valve opening based on the result of comparing the measurement value of the first thermometer with the temperature set value of the foamed particles.

8. The drying hot air line comprises a steam volume control valve provided at the steam intake of the heater, and a second thermometer for measuring the temperature at the top of the dryer. The apparatus for producing foamed particles according to any one of claims 1 to 7, wherein the valve opening of the steam volume control valve is controlled according to the measurement value of the second thermometer, thereby adjusting the temperature of the drying hot air flowing to the dryer.

9. A dryer for drying foamed particles, (a) Having a first outside air intake for taking in outside air and a dryer atmosphere intake for taking in the atmosphere above the dryer, (b) A curing circulation line that passes a curing gas including outside air taken in from the first outside air intake and the atmosphere above the dryer taken in from the dryer atmosphere intake to the dryer, (c) Having a second outside air intake port and a heater for taking in outside air, (d) A drying hot air line that passes the outside air taken in from the second outside air intake port through the heater to the dryer, An air outlet for discharging the curing gas and the drying hot air to the outside, A device for producing foamed particles, comprising: The curing circulation line and the drying hot air line are configured to take in the curing gas and the drying hot air from the bottom of the dryer, respectively, and the air outlet is configured to discharge the curing gas and the drying hot air from the top of the dryer. The drying hot air line comprises a steam volume control valve provided at the steam intake of the heater, and a second thermometer for measuring the temperature at the top of the dryer. A foam particle manufacturing apparatus, wherein the temperature of the drying hot air flowing to the dryer is adjusted by controlling the valve opening of the steam volume control valve according to the measurement value of the second thermometer.

10. A curing process is performed in which a curing gas, including outside air and the atmosphere above the dryer, is passed through a dryer that dries the foamed particles after foaming, and the amount of outside air taken into the curing circulation line is adjusted to gradually lower the temperature of the foamed particles from the temperature immediately after foaming. The process includes installing a drying hot air line through which drying hot air passes to the dryer, and drying the foamed particles after the curing process using the drying hot air, A method for manufacturing foamed particles, comprising a curing preparation step, prior to the curing step, which adjusts the temperature and water vapor pressure of the curing circulation line to match the temperature and water vapor pressure at the start of curing.

11. The method for producing foamed particles according to claim 10, wherein in the curing step, the curing start temperature is set to 95±5°C, and the temperature of the foamed particles is reduced to 85±5°C at a temperature decrease rate of -1.5°C / min or more and less than 0°C / min.

12. The method for producing foamed particles according to claim 10 or 11, wherein in the curing preparation step, steam is introduced into the curing circulation line and the steam is circulated within the curing circulation line.

13. The curing circulation line includes a first outside air intake for taking in outside air, an outside air control valve for adjusting the amount of outside air taken in from the first outside air intake, and a first thermometer for measuring the temperature of the foam particles inside the dryer. A method for manufacturing foamed particles according to any one of claims 10 to 12, wherein in the curing step, the amount of outside air taken in from the first outside air intake is adjusted by controlling the valve opening of the outside air control valve based on the result of comparing the temperature set value of the foamed particles during the curing step with the measurement value of the first thermometer during the curing step.

14. The drying hot air line comprises a heater, a steam volume control valve provided at the steam intake of the heater, and a second thermometer for measuring the temperature at the top of the dryer. A method for producing foamed particles according to any one of claims 10 to 13, wherein in the drying step, the temperature of the drying hot air is adjusted by adjusting the valve opening of the steam volume control valve according to the measurement value of the second thermometer.

15. A method for producing foamed particles according to any one of claims 10 to 14, wherein the foamed particles are polyolefin resin foamed particles.

16. A method for producing a molded article of foamed particles, comprising molding foamed particles obtained by the method for producing foamed particles according to any one of claims 10 to 15.

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