Apparatus and method for manufacturing foamed particles, and method for manufacturing molded body of foamed particles

Abstract

The present invention aims at uniformly preventing the shrinkage of foamed particles in actual machines, and in the foamed particle manufacturing device (10) of the present invention, the maturation circulation line (1) and the drying hot air line (2) are configured in such a way that the maturation gas (A) containing steam, outside air and the atmosphere in the upper part of the dryer (3) and the drying hot air (B) are introduced into the dryer (3) from the lower part of the dryer (3), and the air supply outlet (5) is configured in such a way that the maturation gas (A) and the drying hot air (B) are discharged from the upper part of the dryer (3).

Description

Technical Field

[0001] This invention relates to an apparatus and method for manufacturing foamed granules. Background Technology

[0002] It is known that foamed granules formed from thermoplastic resin are manufactured by the following method (hereinafter referred to as depressurization foaming method): thermoplastic resin granules are dispersed in water containing a dispersant in a pressure vessel, then a volatile foaming agent is added, and the thermoplastic resin granules are impregnated with the volatile foaming agent under high temperature and high pressure, and then the thermoplastic resin granules are discharged under a low-pressure atmosphere. As a method for manufacturing foamed granules using the depressurization foaming method, for example, the technology described in Patent Document 1 is available.

[0003] Figure 3 This is a schematic diagram of the structure of the apparatus for manufacturing foamed particles disclosed in Patent Document 1. For example... Figure 3 As shown, the foamed particle manufacturing apparatus disclosed in Patent Document 1 includes a pressure vessel 303, a valve 304, an opening 305, a low-pressure vessel 306, a conveying medium supply unit 311, a drying suction blower 318, and an air heater 319.

[0004] Within a pressure vessel 303, resin particles 301, composed of a polyolefin resin composition, are dispersed in an aqueous dispersion medium 302. Inside the pressure vessel 303, the resin particles 301 are heated to a temperature above their softening temperature, becoming aqueous resin particles. These particles are then discharged into a low-pressure vessel 306, where the internal pressure is lower than that of the pressure vessel 303, thus foaming. When valve 304 is opened, the resin particles 301 pass through a throttling plate 305 and are discharged into the low-pressure vessel 306 (discharge particles 307).

[0005] In the low-pressure vessel 306, saturated steam is blown in through the steam inlet 308, and the foaming particles, i.e., the discharge particles 307, come into contact with the saturated steam. Furthermore, the discharge particles 307 and the dispersion medium 310 are separated by the filter section 312. The dispersion medium 310 is discharged from the outlet 309. Additionally, the discharge particles 307, together with the conveying medium 314 supplied from the conveying medium supply section 311, are conveyed to the dryer 315 through the outlet 313 of the low-pressure vessel 306. The conveying medium 314 is saturated steam. The pipeline that conveys the discharge particles 307 from the pressure vessel 303 through the low-pressure vessel 306 to the dryer 315 constitutes part of the depressurization foaming circulation pipeline (described later).

[0006] After the discharged particles 307 come into contact with saturated water vapor, they are conveyed to the dryer 315. After the discharged particles 307 are conveyed to the dryer 315, the depressurized foaming circulation pipeline is shut off. Then, while measuring the temperature inside the dryer 315 using a temperature recorder 317, nitrogen gas is introduced into the dryer 315 through the N2 inlet 316 to adjust the nitrogen flow rate, allowing the temperature inside the dryer 315 to drop to the drying temperature over a period of 5 minutes or more. Once the temperature inside the dryer 315 has dropped to the drying temperature, hot air at the drying temperature is introduced into the dryer 315 through a drying air blower 318 and an air heater 319 to dry the foamed particles.

[0007] In the technology described in Patent Document 1, the foamed particles discharged from the pressure vessel 303 are brought into contact with saturated water vapor, cooled to a drying temperature for at least 5 minutes, and then transferred to a drying process. This prevents and reduces the shrinkage of the foamed particles.

[0008] (Existing technical documents)

[0009] Patent Document 1: Japanese Patent Application Publication No. 2000-290420 Summary of the Invention

[0010] (The problem the invention aims to solve)

[0011] In the technology described in Patent Document 1, shrinkage of the foamed particles is prevented and mitigated by performing a curing process in which nitrogen is passed through the depressurized foamed particles to gradually reduce their temperature to the drying temperature. However, the technology described in Patent Document 1 has room for improvement in the following aspects. That is, it is known that even when the technology described in Patent Document 1 is applied to equipment under actual operating conditions, it is not possible to uniformly prevent the shrinkage of the foamed particles, and sometimes the bulk density of the foamed particles is uneven. As a result, the weight of the molded foam body is more uneven, and the surface properties, compressive strength, and other qualities deteriorate.

[0012] One objective of this invention is to provide an apparatus and method for manufacturing foamed particles that can uniformly prevent shrinkage of the foamed particles under actual machine conditions.

[0013] (Technical means used to solve the problem)

[0014] To solve the aforementioned problem, an apparatus for manufacturing foamed particles according to one aspect of the present invention is characterized by having:

[0015] A dryer for drying foamed particles;

[0016] A curing circulation pipeline, (a) having a first outside air inlet for receiving outside air and a dryer atmosphere inlet for receiving the atmosphere above the dryer, and (b) allowing curing gas to flow through the dryer, wherein the curing gas contains outside air received from the first outside air inlet and the atmosphere above the dryer received from the dryer atmosphere inlet.

[0017] A hot air drying duct, (c) having a second outside air inlet for receiving outside air and a heater, and (d) allowing hot air to flow through the dryer, wherein the hot air is formed by the flow of outside air received from the second outside air inlet through the heater; and

[0018] An air outlet is provided to discharge the curing gas and the drying hot air to the outside.

[0019] The curing circulation pipeline and the drying hot air pipeline are respectively configured such that the curing gas and the drying hot air are introduced into the dryer from the bottom of the dryer, and the air outlet is configured such that the curing gas and the drying hot air are discharged from the top of the dryer.

[0020] To solve the aforementioned problem, a method for manufacturing foamed granules according to one aspect of the present invention is characterized by comprising:

[0021] Curing process: A curing circulation pipeline is set up to allow curing gas to flow through the dryer, and the temperature of the foamed particles is gradually reduced from the initial foaming temperature by adjusting the amount of external gas received by the curing circulation pipeline; wherein the curing gas contains the external gas and the atmosphere above the dryer; and

[0022] Drying process: A hot air duct is provided to allow hot air to flow through the dryer. This hot air is used to dry the foamed particles after the curing process.

[0023] The manufacturing method includes, prior to the curing process, a curing preparation process, in which the temperature and vapor pressure of the curing circulation pipeline are made consistent with the temperature and vapor pressure at the start of curing.

[0024] (The effect of the invention)

[0025] According to one aspect of the present invention, it is possible to uniformly prevent the shrinkage of foamed particles under actual machine conditions. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of a foamed particle manufacturing apparatus according to an embodiment of the present invention.

[0027] Figure 2This is a schematic diagram of a traditional foamed particle manufacturing device.

[0028] Figure 3 This is a schematic diagram of the structure of the foamed particle manufacturing apparatus disclosed in Patent Document 1. Detailed Implementation

[0029] (Technical concept of this invention: regarding the ripening process)

[0030] The curing process of foamed particles involves introducing external air into a dryer containing the foamed particles, thereby replacing the water vapor in the particles with air. This curing process helps to suppress the shrinkage of the foamed particles.

[0031] After being foamed in a steam atmosphere using a depressurization foaming method, the foamed particles are stored in a dryer. When hot drying air is blown into the freshly foamed particles for drying, the particles are exposed to a rapidly decreasing temperature environment, causing the water vapor within the particles to condense. As a result, the foamed particles shrink.

[0032] Therefore, during the curing process, external air is slowly introduced into the dryer containing the freshly foamed granules, causing the temperature of the granules to gradually decrease, thereby preventing shrinkage. Additionally, lowering the temperature of the granules hardens the resin that makes them up, which also helps to suppress shrinkage.

[0033] Here, in the curing process, in order to prevent the foamed particles from shrinking, it is necessary to control them to the following states (A) and (B). That is, (A) the state in which the resin constituting the foamed particles cools and hardens; and (B) the state in which water vapor condensation is mitigated, wherein the water vapor condenses due to the rapid drop in temperature caused by the inflow of air into the foamed particles.

[0034] The temperature of the foamed particles is adjusted to achieve state (A) above, and the air volume of the foamed particles is adjusted to achieve state (B) above. Here, in the foamed particles, if water vapor is cooled at normal pressure, air will definitely be present (flowing in), therefore, there is a correlation between temperature and air volume.

[0035] Therefore, the conditions (A) and (B) described above can be adjusted by controlling the temperature of the foamed particles (corresponding to the air volume). Furthermore, the curing process can be managed by controlling both the rate at which the temperature of the foamed particles decreases (corresponding to the air inflow rate) and the temperature reached during curing (corresponding to the total air inflow). This is a new discovery by the inventors.

[0036] While the manufacturing apparatus disclosed in Patent Document 1 can perform the aforementioned curing process, there is still room for improvement in uniformly preventing the shrinkage of the foamed particles in actual operation. In view of this situation, the inventors conducted in-depth research with the aim of providing a manufacturing apparatus capable of uniformly preventing the shrinkage of foamed particles for actual use in the manufacture of foamed particles, and as a result, the present invention was completed.

[0037] (Structure of the foamed particle manufacturing apparatus of this embodiment)

[0038] Hereinafter, one embodiment of the present invention will be described in detail. Figure 1 This is a schematic diagram of the structure of the foamed particle manufacturing apparatus 10 of this embodiment.

[0039] like Figure 1 As shown, the manufacturing apparatus 10 includes a depressurized foaming circulation pipeline J, a curing circulation pipeline 1, a drying hot air pipeline 2, a dryer 3 for drying the foamed particles, and a blower S. In the manufacturing apparatus 10 of this embodiment, undried foamed particles conveyed by the depressurized foaming circulation pipeline J are introduced into the dryer 3. The foamed particles are cured and dried in the dryer 3. In addition, the blower S delivers the gas flowing in the curing circulation pipeline 1 and the drying hot air pipeline 2 to the dryer 3.

[0040] The depressurized foaming circulation pipeline J is a conveying pipeline used to transport foamed particles manufactured by the depressurized foaming method. The depressurized foaming circulation pipeline J introduces steam from the outside and circulates the conveying medium for the foamed particles. The depressurized foaming circulation pipeline J includes piping and equipment connected to the piping capable of achieving foaming based on the depressurized foaming method; there are no particular limitations. For example, the depressurized foaming circulation pipeline J is a circulation pipeline consisting of a pressure vessel, a low-pressure vessel (e.g., a foaming cylinder), a dewatering machine, a dryer, etc., wherein the pressure vessel contains resin particles, etc., which are the raw materials for the foamed particles, and the low-pressure vessel is a space for the resin particles impregnated with foaming agent to be discharged from the pressure vessel. Such a depressurized foaming circulation pipeline J is shown, for example, in Figures 6 and 7 of International Publication WO2020 / 158061.

[0041] The curing circulation pipeline 1 is used to adjust the curing process of the foamed particles in the dryer 3. The curing circulation pipeline 1 is a separate piping system from the depressurization foaming circulation pipeline J. The curing circulation pipeline 1 introduces external air and steam from the outside.

[0042] The curing circulation pipeline 1 includes a curing external gas inlet 1a (first external gas inlet), an external gas regulating valve 1b, a curing thermometer 1c (first thermometer), an on / off valve 1d, a circulation flow regulating valve 1e, a dryer atmosphere inlet 1f, a curing steam inlet 4a, and an on / off valve 4b. The curing steam inlet 4a is provided to introduce curing steam into the curing circulation pipeline 1. The dryer atmosphere inlet 1f is provided to introduce the atmosphere from the upper part of the dryer 3. The curing circulation pipeline 1 allows gas A (curing gas) containing external gas introduced from the external gas inlet 1a and the atmosphere from the upper part of the dryer 3 introduced from the dryer atmosphere inlet 1f to flow through the dryer 3. The external gas regulating valve 1b is a valve that regulates the amount of external gas introduced from the external gas inlet 1a. The thermometer 1c measures the temperature of the foaming particles inside the dryer 3. The measured value of the thermometer 1c is notified to the external gas regulating valve 1b. Furthermore, the external air regulating valve 1b controls the valve opening based on a comparison between the measured value of the thermometer 1c and the predetermined temperature setting value of the foamed particles, thereby regulating the amount of external air introduced from the external air inlet 1a. The on / off valve 1d switches the flow of gas A into the dryer 3. The circulation flow regulating valve 1e adjusts the flow rate of gas A. In the curing circulation pipeline 1, gas A flows through the dryer 3 via the blower S. In the manufacturing apparatus 10, when the foamed particles are curing in the dryer 3, the on / off valve 1d is open, and gas A flows through the dryer 3. On the other hand, when the foamed particles are not curing (e.g., during drying), the on / off valve 1d is closed, and gas A does not flow into the dryer 3.

[0043] The drying hot air duct 2 includes a drying outside air inlet 2a (second outside air inlet), a heater 2b, an on / off valve 2c, and a drying thermometer 2d (second thermometer). Additionally, a steam flow regulating valve 2e is provided at the steam inlet of the heater 2b. In the drying hot air duct 2, by opening the on / off valve 2c, outside air is introduced through the outside air inlet 2a, and this outside air flows through the heater 2b to generate drying hot air B. The drying hot air duct 2 then allows the generated drying hot air B to flow through the dryer 3. The thermometer 2d measures the temperature of the upper part inside the dryer 3. The opening degree of the steam flow regulating valve 2e is controlled based on the temperature measured by the thermometer 2d. Furthermore, the temperature of the drying hot air B flowing to the dryer 3 is adjusted accordingly.

[0044] In the hot air drying duct 2, hot air B flows through the dryer 3 via the blower S. During the drying of the foamed particles, the on / off valve 1d of the curing circulation duct 1 is closed, and the on / off valve 2c is open, allowing the hot air B to flow through the dryer 3. Meanwhile, the on / off valve 4b for introducing steam into the curing circulation duct 1 is closed at this time. On the other hand, when the foamed particles are not being dried (e.g., during curing), the on / off valve 2c is closed, preventing the hot air B from flowing into the dryer 3.

[0045] Dryer 3 can employ a conventionally known structure used in the drying of foamed particles. Figure 1 In the structure shown, the lower part of the dryer 3 has a conical outer sleeve 31, which has a perforated plate 3e inside for gas to pass through. Furthermore, the shape of the outer sleeve 31 is not particularly limited and can also be a polyhedral pyramid shape. Preferably, the outer sleeve 31 is conical.

[0046] like Figure 1 As shown, the dryer 3 includes a main body 3a for containing foamed particles, multiple gas inlets 3b, multiple flow control valves 3c, an outer casing 31, and an orifice plate 3e. The outer casing 31 includes multiple gaps 3d and an orifice plate 3e. The gas inlets 3b are inlets for introducing gas A and hot drying air B into the main body 3a. The flow control valves 3c are configured to correspond to the gas inlets 3b. Additionally, each gap 3d is configured to correspond to both the gas inlets 3b and the flow control valves 3c. In the dryer 3, the gas inlets 3b are shared as both inlets for introducing gas A into the main body 3a and inlets for introducing hot drying air B into the main body 3a. However, this is not a limitation; the gas inlets may also be separately configured as inlets for introducing gas A and inlets for introducing hot drying air B.

[0047] Furthermore, each gap 3d forms a sleeve covering the outer periphery of the conical portion covering the lower part of the main body 3a. Each gap 3d has a space for gas introduced from the gas inlet 3b corresponding to that gap 3d to be retained. The perforated plate 3e has an opening that connects this space to the interior of the main body 3a. The shape of this opening is not particularly limited; for example, it can be a metal mesh, perforated metal, or a slit.

[0048] The flow rate of gas flowing into the main body 3a from each gas inlet 3b can be set for each of the multiple idle sections 3d by adjusting the opening degree or switching the opening and closing of each flow regulating valve 3c. Thus, the manufacturing apparatus 10 regulates 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. Consequently, the curing process can be controlled more uniformly for the foamed particles contained in the dryer 3.

[0049] Here, as Figure 1As shown, the manufacturing apparatus 10 of this embodiment includes an air outlet 5 for discharging gas A and hot drying air B to the outside. The curing circulation pipe 1 and the hot drying air pipe 2 are configured such that gas A and hot drying air B can be omnidirectionally introduced into the dryer 3 from the lower part of the dryer 3 body 3a. Furthermore, the air outlet 5 is located at the upper part of the dryer 3, discharging gas A and hot drying air B from the upper part of the dryer 3 body 3a. Therefore, during the curing process, gas A can be uniformly contacted with the foamed particles contained in the dryer 3. Similarly, during the drying process, hot drying air B can be uniformly contacted with the foamed particles contained in the dryer 3. Moreover, the above structure is not affected by the size of the dryer 3, and can achieve the same effect for the manufacturing apparatus 10 in actual operation. Furthermore, according to the structure of the manufacturing apparatus 10, the hot drying air pipe 2 can introduce outside air from the outside air inlet 2a to control the temperature inside the dryer 3 according to a set value. Therefore, during the curing process, the actual machine used in the manufacturing of foamed particles can be used to uniformly prevent the shrinkage of the foamed particles.

[0050] Furthermore, according to the manufacturing apparatus 10, the shrinkage of the foamed particles can be prevented uniformly, thus suppressing the non-uniformity of the bulk density of the foamed particles. Consequently, for the molded article formed using the foamed particles, its weight non-uniformity can be reduced, and its surface properties, compressive strength, and other qualities can be improved.

[0051] Furthermore, according to the manufacturing apparatus 10, gas A and drying hot air B can be uniformly contacted with the foamed particles, thus shortening the curing time and drying time. Therefore, the manufacturing of foamed particles can be made more efficient, and the energy and cost required for the manufacturing process can be reduced.

[0052] Figure 2 This is a schematic diagram of a conventional foamed particle manufacturing apparatus 20. In the manufacturing apparatus 20, a drying hot air duct 22 introduces external air for curing and external air for drying. In the drying hot air duct 22, the external air for curing is introduced into the dryer 23 through an external air inlet 22a via a blower S1. The amount of external air for curing is controlled by switching on and off the on / off valve 22b and adjusting the opening degree of the regulating valve 22c. Alternatively, an external air inlet 22d for curing may be provided in the manufacturing apparatus 20 as needed. The external air for curing is introduced into the dryer 23 through a blower S2. The flow rate of the external air for curing is controlled by switching on and off the on / off valve 22f and adjusting the opening degree of the regulating valve 22e. The external air for curing comes into partial contact with the foamed particles contained in the dryer 23.

[0053] Additionally, outside air for drying is introduced through the outside air inlet 22g by opening the on / off valve 22i. The introduced outside air is then heated by the heater 22h to become hot drying air. This hot drying air is then introduced into the dryer 23 by the blower S1. The temperature of the hot drying air is controlled by the steam flow regulating valve 22k. The hot drying air comes into partial contact with the foaming particles contained in the dryer 23. Thermometer 22j measures the temperature in the upper part of the dryer 23. The opening of the steam flow regulating valve 22k is controlled based on the temperature reading from thermometer 22j. This, in turn, regulates the temperature of the hot drying air flowing into the dryer 23.

[0054] Thus, in the conventional manufacturing apparatus 20, the curing gas and the drying hot air come into partial contact with the foamed particles. In this configuration, if the size of the dryer 23 becomes larger, it becomes difficult to ensure that the curing gas and drying hot air contact the foamed particles contained within the dryer 23 evenly. Therefore, in the conventional manufacturing apparatus 20, during actual use, it is impossible to uniformly prevent the foamed particles from shrinking and to dry them during the curing and drying processes. As a result, uneven bulk density or uneven drying of the foamed particles occurs.

[0055] (Manufacturing method of foamed granules)

[0056] The method for manufacturing foamed particles according to this embodiment includes a curing process and a drying process. In the curing process, a curing circulation pipe is provided to allow curing gas to flow through a dryer, and the temperature of the foamed particles is gradually reduced from the temperature immediately after foaming by adjusting the amount of outside gas flowing through this curing circulation pipe. The curing gas contains the outside gas and the atmosphere above the dryer. In the drying process, a drying hot air pipe is provided to allow drying hot air to flow through the dryer, and this drying hot air is used to dry the foamed particles after the curing process. Furthermore, the method for manufacturing foamed particles according to this embodiment is characterized by including a curing preparation process before the curing process. In this curing preparation process, the temperature and vapor pressure within the curing circulation pipe are preheated to match the temperature and vapor pressure at the start of curing. The curing preparation process is a process of preheating the curing circulation pipe. In the curing preparation process, the curing circulation pipe is preheated by introducing steam. Furthermore, the timing of the curing preparation step is not particularly limited, as long as it occurs before the curing process. For example, the curing preparation step can be performed before foaming the resin particles using the depressurization foaming method. In this case, the temperature and vapor pressure at the start of curing are equivalent to the temperature and vapor pressure after foaming. Additionally, in the foaming particle manufacturing method of this embodiment, in addition to the curing preparation step, a depressurization foaming preparation step can also be performed to preheat the depressurization foaming circulation pipeline. The curing preparation step and the depressurization foaming preparation step can be performed simultaneously. That is, when performing the curing preparation step, in addition to preheating the curing circulation pipeline, the depressurization foaming circulation pipeline can also be preheated. Alternatively, the curing preparation step and the depressurization foaming preparation step can also be performed separately.

[0057] The following describes a method for manufacturing foamed granules according to this embodiment, which is performed in the following order: curing preparation step, foaming step of resin granules using depressurization foaming method, curing step, and drying step. However, the manufacturing method for foamed granules according to this embodiment is not limited to this order.

[0058] Furthermore, the method for manufacturing foamed granules in this embodiment is not particularly limited as long as it is a method capable of performing the curing process, the drying process, and the curing preparation process. For example, the method for manufacturing foamed granules in this embodiment can be described using... Figure 1 The method of manufacturing the apparatus 10 shown. Hereinafter, as a method for manufacturing foamed particles according to this embodiment, a method for using... Figure 1 The method of manufacturing apparatus 10 shown will be described. In addition, an example of performing the curing preparation process and the depressurization foaming preparation process simultaneously (hereinafter, this process is sometimes referred to as the foaming and curing preparation process) will be described below.

[0059] (Foaming and Curing Preparation Process)

[0060] The foaming and curing preparation process is performed before the foaming process of the resin particles begins. In the curing preparation process, the temperature and water vapor pressure in the curing circulation pipeline 1 are made the same as the temperature at the beginning of curing (i.e., the temperature after the foaming is completed) and water vapor pressure beforehand.

[0061] In the foaming and curing preparation process, the on / off valve 1d of the curing circulation pipeline 1 is opened. Additionally, the on / off valve 4b of the curing steam inlet 4a of the curing circulation pipeline 1 is opened, introducing steam from the curing steam inlet 4a into the curing circulation pipeline 1, causing the steam to circulate within the curing circulation pipeline 1. Furthermore, all multiple flow regulating valves 3c are opened, allowing steam to flow into the main body 3a. Finally, the external air regulating valve 1b is closed, preventing the introduction of external air from the external air inlet 1a.

[0062] In addition, during the foaming and curing preparation process, steam circulates not only in the curing circulation pipeline but also in the depressurized foaming circulation pipeline J. At this time, the on / off valve (not shown) of the steam inlet (not shown) of the depressurized foaming circulation pipeline J is opened, and steam is introduced into the depressurized foaming circulation pipeline J from this steam inlet. The steam introduced into the depressurized foaming circulation pipeline J flows into the main body 3a through the inlet of the undried foamed particles.

[0063] In this way, during the foaming and curing preparation process, steam circulates in both the depressurized foaming circulation line J and the curing circulation line 1. Furthermore, steam is introduced into the main body 3a of the dryer 3 from both the depressurized foaming circulation line J and the curing circulation line 1. When the temperature and vapor pressure within the system including the depressurized foaming circulation line J, the curing circulation line 1, and the dryer 3 become the same as the temperature at the start of curing (i.e., the temperature at the end of foaming) and the vapor pressure, the steam introduction is stopped, and the curing preparation process ends. Then, the foaming process, which is the next process, begins. The starting temperature for curing is approximately 95±5℃.

[0064] If a preheating / curing preparation process, at least preheating the curing circulation pipe 1, is not implemented, it means that unconditioned cold air from the curing circulation pipe 1 will flow into the dryer 3 at the start of curing. Consequently, the foamed particles located near the gas inlet within the main body 3a of the dryer 3 cool rapidly and shrink. Furthermore, due to the condensation of water vapor within the main body 3a, outside air intrudes from the air outlet of the dryer 3, causing the temperature of the foamed particles to decrease. This results in the shrinkage of the foamed particles.

[0065] Additionally, if the temperature of the curing circulation line 1 is lower than the curing start temperature (e.g., 95±5°C) when the curing process is about to begin, steam is introduced into the curing circulation line 1. This raises the temperature of the curing circulation line 1 so that the temperature inside the curing circulation line 1 is close to the curing start temperature inside the dryer 3, and then curing begins.

[0066] The foaming and curing preparation process is carried out before the depressurization foaming begins, so as to make the temperature inside the dryer 3 the same as the temperature inside the curing circulation pipeline 1. Preferably, the temperature inside the dryer 3 and the temperature inside the curing circulation pipeline 1 are 95±5°C.

[0067] (Cooking process)

[0068] A foaming process is performed before the curing process. Any known foaming technique can be used as long as the depressurization foaming method is employed. In the curing process, freshly foamed, undried foamed particles are fed into the main body 3a of the dryer 3. By adjusting the amount of external air flowing in the curing circulation pipe 1, the temperature of the foamed particles is gradually reduced from their initial foaming temperature.

[0069] During the curing process, the curing circulation pipeline 1 is configured to introduce both external air from the external air inlet 1a and the steam atmosphere from the upper part of the dryer 3, so that gas A containing both the external air and the atmosphere from the upper part of the dryer 3 flows through the dryer 3. As a result, gas A comes into contact with the foaming particles inside the dryer 3.

[0070] Then, according to the specified temperature setting conditions for the foamed particles in 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 between the temperature setting value of the foamed particles in the curing process and the measurement value of the thermometer 1c in the curing process, the opening degree of the external air regulating valve 1b is controlled, thereby adjusting the external air intake from the external air inlet 1a. In this way, by adjusting the external air intake from the external air inlet 1a, the introduced external air is mixed with the atmosphere from the upper part of the dryer 3, thereby enabling the temperature of the foamed particles in the dryer 3 to be reduced slowly and with high precision.

[0071] The temperature setting conditions for the foamed particles in the curing process are not particularly limited, and can be appropriately set according to the structure of the manufacturing apparatus 10, the expected characteristics of the foamed particles, etc. Preferably, in the curing process, the curing start temperature is set to 95±5°C, and the temperature of the foamed particles is reduced to 85±5°C.

[0072] Furthermore, if the temperature drop rate of the foamed particles during the curing process is too high, the temperature drop becomes rapid, causing the foamed particles to shrink. On the other hand, if the temperature drop rate is too low, the production efficiency of the foamed particles will deteriorate. From this perspective, the temperature drop rate of the foamed particles during the curing process is preferably -1.5°C / min or higher and less than 0°C / min, more preferably -0.7°C / min. Furthermore, the temperature drop time is preferably 20 ± 10 minutes.

[0073] (Drying process)

[0074] In the drying process, hot air B is flowed through the dryer 3 via the hot air drying duct 2 to dry the foamed particles.

[0075] In the drying process, firstly, the on / off valve 1d of the curing circulation pipeline 1 is closed. Then, outside air is introduced from the outside air inlet 2a of the drying hot air pipeline 2, and this outside air flows through the heater 2b, thereby generating drying hot air B. Then, the drying hot air B flows through the dryer 3. In addition, the temperature of the drying hot air B is adjusted by adjusting the opening of the steam quantity adjustment valve 2e according to the measured value of the thermometer 2d. The temperature of the drying hot air B is adjusted according to 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 appropriately set according to the characteristics of the foamed particles and the structure of the manufacturing apparatus 10.

[0076] (Foaming Granules)

[0077] In this embodiment, the raw material used for foaming granules can be any material capable of being foamed by the aforementioned depressurization foaming method, and must contain at least a crystalline thermoplastic resin and a foaming agent. Furthermore, in addition to the crystalline thermoplastic resin and foaming agent, various additives can be added as needed as the raw material for foaming granules. Examples include flame retardants, heat stabilizers, free radical generators, processing aids, weathering 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.

[0078] The thermoplastic resin used in this embodiment is any generally known crystalline thermoplastic resin with foaming properties, and is not particularly limited. Examples of such thermoplastic resins 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.

[0079] Examples of polyester resins include aliphatic polyester resins, aromatic polyester resins, and aliphatic-aromatic polyester resins. Specific examples of polyester resins include polyhydroxyalkanoates, polybutylene succinate (PBS), poly(butylene terephthalate adipate) (PBAT), and polyethylene terephthalate (PET). Furthermore, the polyhydroxyalkanoate is selected from at least one of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), poly(3-hydroxybutyrate) (P3HB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), and poly(3-hydroxybutyrate-co-3-hydroxyoctadecanoate).

[0080] Furthermore, as a polyolefin resin, there are no particular limitations; for example, the polyolefin resins exemplified in International Publication WO2020 / 158061 can be cited.

[0081] [Manufacturing method of foamed granules]

[0082] The method for manufacturing the molded body of foamed particles in this embodiment is a method for molding the foamed particles obtained by the above-described manufacturing method. To manufacture the molded body of foamed particles, the foamed particles can be molded using known methods.

[0083] This invention is not limited to the above-described embodiments. Various modifications can be made within the scope shown in the specification. Embodiments obtained by appropriately combining the technical means disclosed in the embodiments are also included within the technical scope of this invention.

[0084] 〔Summarize〕

[0085] The foamed particle manufacturing apparatus 10 of Embodiment 1 of the present invention comprises: a dryer 3 for drying the foamed particles; a curing circulation pipeline 1, (a) having a first outside air inlet (outside air inlet 1a) for receiving outside air and a dryer atmosphere inlet 1f for receiving the atmosphere above the dryer 3, and (b) allowing curing gas (gas A) to flow through the dryer 3, wherein the curing gas contains outside air received from the first outside air inlet and the atmosphere above the dryer 3 received from the dryer atmosphere inlet 1f; and a drying hot air pipeline 2, (c) having a second outside air inlet... The dryer 3 includes an external air inlet (external air inlet 2a) and a heater 2b, and (d) allows hot dry air B to flow through the dryer 3, the hot dry air B being formed by external airflow received from the second external air inlet passing through the heater 2b; and an air outlet 5 for discharging the curing gas and the hot dry air B to the outside, the curing circulation pipe 1 and the hot dry air pipe 2 being configured such that the curing gas and the hot dry air B are introduced into the dryer 3 from the lower part of the dryer 3, and the air outlet 5 being configured such that the curing gas and the hot dry air B are discharged from the upper part of the dryer 3.

[0086] Based on Method 1, in the foamed particle manufacturing apparatus 10 of Method 2 of the present invention, a plurality of gas inlets 3b are provided at the lower part of the dryer 3 for introducing the curing gas (gas A) and the drying hot air B, and the gas flow rate introduced into the dryer 3 is adjusted by changing the valve opening of the gas inlets 3b.

[0087] Based on method 1 or 2, in the foaming particle manufacturing apparatus 10 of method 3 of the present invention, the lower part of the dryer 3 has an outer jacket 31, which has a perforated plate 3e for gas to pass through inside.

[0088] Based on any of embodiments 1 to 3, in the foamed particle manufacturing apparatus 10 of embodiment 4 of the present invention, the curing circulation pipeline 1 further includes a steam inlet (curing steam inlet 4a) for receiving steam.

[0089] Based on any one of methods 1 to 4, in the foamed particle manufacturing apparatus 10 of method 5 of the present invention, the foamed particles are polyolefin resin foamed particles.

[0090] Based on any of embodiments 1 to 5, in the foamed particle manufacturing apparatus 10 of embodiment 6 of the present invention, the curing circulation pipeline 1 includes: an external air regulating valve 1b that regulates the amount of external air received from the first external air inlet (external air inlet 1a); and a first thermometer (thermometer 1c) that measures the temperature of the foamed particles in the dryer 3. The external air regulating valve 1b controls the valve opening based on a comparison between the measured value of the first thermometer and the temperature set value of the foamed particles, thereby regulating the amount of external air introduced from the first external air inlet.

[0091] Based on any of embodiments 1 to 6, in the foamed particle manufacturing apparatus 10 of embodiment 7 of the present invention, the drying hot air duct 2 includes: a steam quantity regulating valve 2e, which is provided at the steam inlet of the heater 2b; and a second thermometer (thermometer 2d), which measures the temperature of the upper part inside the dryer 3, and controls the valve opening of the steam quantity regulating valve 2e according to the measured value of the second thermometer, thereby regulating the temperature of the drying hot air B flowing to the dryer 3.

[0092] The method for manufacturing foamed particles according to embodiment 8 of the present invention includes:

[0093] Curing process: A curing circulation pipeline 1 is set up to allow curing gas (gas A) to flow through the dryer 3, and the temperature of the foamed particles is gradually reduced from the temperature immediately after foaming by adjusting the amount of external gas received by the curing circulation pipeline 1. The curing gas (gas A) contains external gas and the atmosphere above the dryer 3. The dryer 3 dries the foamed particles after foaming.

[0094] Drying process: A hot air duct 2 is provided to allow hot air B to flow through the dryer 3. The foamed particles after the curing process are dried using this hot air B.

[0095] The manufacturing method includes, prior to the curing process, a curing preparation process, in which the temperature and vapor pressure of the curing circulation pipeline 1 are made consistent with the temperature and vapor pressure at the start of curing.

[0096] Based on Method 8, in the method for manufacturing foamed particles according to Method 9 of the present invention, in the curing process, the curing start temperature is set to 95±5℃, and the temperature of the foamed particles is reduced to 85±5℃ at a temperature decrease rate of -1.5℃ / min or higher and less than 0℃ / min.

[0097] Based on method 8 or 9, in the method for manufacturing foamed particles of method 10 of the present invention, steam is introduced into the curing circulation pipeline 1 in the curing preparation step, so that the steam circulates in the curing circulation pipeline 1.

[0098] Based on any of embodiments 8 to 10, in the method for manufacturing foamed particles according to embodiment 11 of the present invention, the curing circulation pipeline 1 includes: a first external air inlet (external air inlet 1a) for receiving external air, an external air regulating valve 1b for adjusting the amount of external air received from the first external air inlet, and a first thermometer (thermometer 1c) for measuring the temperature of the foamed particles in the dryer 3. In the curing process, the opening degree of the external air regulating valve 1b is controlled based on the comparison result between the temperature set value of the foamed particles in the curing process and the measured value of the first thermometer in the curing process, thereby adjusting the amount of external air intake from the first external air inlet.

[0099] Based on any of embodiments 8 to 11, in the method for manufacturing foamed particles according to embodiment 12 of the present invention, the drying hot air duct 2 includes: a heater 2b, a steam quantity regulating valve 2e disposed at the steam inlet of the heater 2b, and a second thermometer (thermometer 2d) for measuring the temperature of the upper part inside the dryer 3. In the drying process, the opening degree of the steam quantity regulating valve 2e is adjusted according to the measured value of the second thermometer, thereby adjusting the temperature of the drying hot air.

[0100] Based on any of embodiments 8 to 12, in the method for manufacturing foamed particles of embodiment 13 of the present invention, the foamed particles are polyolefin resin foamed particles.

[0101] The method for manufacturing a molded body of foamed particles according to embodiment 14 of the present invention is to mold foamed particles obtained by any one of the methods for manufacturing foamed particles according to embodiments 8 to 12.

[0102] <Explanation of Figure Markers>

[0103] 1. Mature circulation pipeline

[0104] 1a External air inlet (first external air inlet)

[0105] 1b External air regulating valve

[0106] 1c Thermometer (First Thermometer)

[0107] 1f Dryer Atmosphere Inlet

[0108] 2. Drying hot air duct

[0109] 2a External air inlet (second external air inlet)

[0110] 2b Heater

[0111] 2d thermometer (second thermometer)

[0112] 2e Steam quantity regulating valve

[0113] 3. Dryer

[0114] 31. Outerwear

[0115] 3b Gas inlet

[0116] 3e orifice plate

[0117] 4a. Curing steam inlet (steam inlet)

[0118] 5. Air supply outlet

[0119] A gas (for aging)

[0120] B. Dry, hot air.

Claims

1. An apparatus for manufacturing foamed granules, comprising: A dryer for drying foamed particles; A curing circulation pipeline, (a) having a first outside air inlet for receiving outside air and a dryer atmosphere inlet for receiving the atmosphere above the dryer, and (b) allowing curing gas to flow through the dryer, wherein the curing gas contains outside air received from the first outside air inlet and the atmosphere above the dryer received from the dryer atmosphere inlet. A hot air drying duct, (c) having a second outside air inlet for receiving outside air and a heater, and (d) allowing hot air to flow through the dryer and contacting the hot air with foamed particles contained in the dryer, wherein the hot air is formed by the flow of outside air received from the second outside air inlet through the heater; and An air outlet is provided to discharge the curing gas and the drying hot air to the outside. The curing circulation pipeline and the drying hot air pipeline are respectively configured such that the curing gas and the drying hot air are introduced into the dryer from the bottom of the dryer, and the air outlet is configured such that the curing gas and the drying hot air are discharged from the top of the dryer. The curing circulation pipeline also has a steam inlet for receiving steam. The aging circulation pipeline includes: An outside air regulating valve that regulates the amount of outside air received from the first outside air inlet; and The first thermometer measures the temperature of the foamed particles inside the dryer. The external air regulating valve controls the valve opening based on the comparison between the measured value of the first thermometer and the temperature set value of the foaming particles, thereby regulating the amount of external air received from the first external air inlet.

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

3. The apparatus for manufacturing foamed granules according to claim 1 or 2, wherein, The lower part of the dryer has an outer sleeve, inside which there is a perforated plate for gas to pass through.

4. The apparatus for manufacturing foamed particles according to claim 1 or 2, wherein, The foamed particles are polyolefin resin foamed particles.

5. The apparatus for manufacturing foamed particles according to claim 1 or 2, wherein, The drying hot air duct is equipped with: A steam flow regulating valve is provided at the steam inlet of the heater; and The second thermometer measures the temperature in the upper part of the dryer. The opening degree of the steam quantity regulating valve is controlled according to the measured value of the second thermometer, thereby regulating the temperature of the drying hot air flowing to the dryer.

6. A method for manufacturing foamed granules, comprising: Curing process: A curing circulation pipeline is set up to allow curing gas to flow through the dryer, and the temperature of the foamed particles is gradually reduced from the initial foaming temperature by adjusting the amount of external gas received by the curing circulation pipeline; wherein the curing gas contains the external gas and the atmosphere above the dryer; and Drying process: A hot air duct is provided to allow hot air to flow through the dryer. This hot air is used to dry the foamed particles after the curing process. The manufacturing method includes, prior to the curing process, a curing preparation process, in which the temperature and vapor pressure of the curing circulation pipeline are made consistent with the temperature and vapor pressure at the start of curing. The curing circulation pipeline includes: a first outside air inlet for receiving outside air, an outside air regulating valve for adjusting the amount of outside air received from the first outside air inlet, and a first thermometer for measuring the temperature of the foaming particles inside the dryer. In the curing process, the opening degree of the external air regulating valve is controlled based on the comparison between the temperature set value of the foaming particles in the curing process and the measured value of the first thermometer in the curing process, thereby regulating the amount of external air intake from the first external air inlet.

7. The method for manufacturing foamed granules according to claim 6, wherein, In the curing process, the curing start temperature is set to 95±5℃, and the temperature of the foamed particles is reduced to 85±5℃ at a temperature decrease rate of -1.5℃ / min or higher and less than 0℃ / min.

8. The method for manufacturing foamed granules according to claim 6 or 7, wherein, In the curing preparation process, steam is introduced into the curing circulation pipeline to circulate the steam within the curing circulation pipeline.

9. The method for manufacturing foamed granules according to claim 6 or 7, wherein, The drying hot air duct includes: a heater, a steam flow regulating valve installed at the steam inlet of the heater, and a second thermometer for measuring the temperature of the upper part of the dryer. In the drying process, the opening degree of the steam quantity regulating valve is adjusted according to the measured value of the second thermometer, thereby regulating the temperature of the drying hot air.

10. The method for manufacturing foamed granules according to claim 6 or 7, wherein, The foamed particles are polyolefin resin foamed particles.

11. A method for manufacturing a shaped body of foamed granules, wherein the foamed granules obtained by the method for manufacturing foamed granules according to any one of claims 6 to 10 are shaped.

Images