WO2023026611A1 - 物理発泡剤導入用フィルタ、発泡成形体の製造装置および製造方法 - Google Patents
物理発泡剤導入用フィルタ、発泡成形体の製造装置および製造方法 Download PDFInfo
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- WO2023026611A1 WO2023026611A1 PCT/JP2022/020691 JP2022020691W WO2023026611A1 WO 2023026611 A1 WO2023026611 A1 WO 2023026611A1 JP 2022020691 W JP2022020691 W JP 2022020691W WO 2023026611 A1 WO2023026611 A1 WO 2023026611A1
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- introduction
- molten resin
- foaming agent
- physical foaming
- zone
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Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
- B29C44/34—Auxiliary operations
- B29C44/36—Feeding the material to be shaped
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
Definitions
- the present invention relates to a filter for introducing a physical foaming agent, an apparatus for manufacturing a foam molded body, and a manufacturing method.
- Patent Literature 1 discloses a method of molding a foam molded article using relatively low-pressure nitrogen, carbon dioxide, or the like without using a supercritical fluid. According to this method, fine foamed cells can be formed in a molded article by a simple process using a low-pressure physical foaming agent without using a special high-pressure device.
- the method for producing a foamed molded product described in Patent Document 1 has a plasticization zone in which a thermoplastic resin is plasticized and melted to become a molten resin, and a starvation zone in which the molten resin is in a starvation state.
- the manufacturing method includes: plasticizing and melting a thermoplastic resin to form the molten resin; supplying a pressurized fluid containing the physical blowing agent at a constant pressure to the introduction speed adjusting container; introducing a pressurized fluid at a constant pressure to maintain the starvation zone at the constant pressure; starving the molten resin in the starvation zone; and maintaining the starvation zone at the constant pressure. contacting the molten resin in the starved state with the pressurized fluid in the starvation zone, and molding the molten resin in contact with the pressurized fluid containing the physical blowing agent into a foamed molding.
- a vent-up is performed in which the molten resin in the starvation zone flows back into the introduction port for introducing the physical foaming agent provided in the cylinder, which is open to the starvation zone.
- the molten resin may solidify and remain in the inlet. If the resin hardens and remains in the inlet, the physical foaming agent cannot be stably supplied, so it is necessary to remove the residual resin, which takes time and effort.
- the gas in the plasticizing cylinder is degassed during cleaning after the molding of the foam is completed, the gas (physical foaming agent) accumulated in the introduction speed adjusting container is introduced into the plasticizing cylinder at once. Therefore, there may be a loud gunshot sound.
- the present invention has been made in view of the above circumstances, and is for introducing a physical foaming agent that can stably supply a physical foaming agent to a starvation zone (a zone where a starved molten resin exists) by suppressing vent-up.
- An object of the present invention is to provide a filter, a manufacturing apparatus for a foamed molding, and a manufacturing method.
- Another object of the present invention is to provide an apparatus and a method for manufacturing a foamed molded article that can suppress the occurrence of a loud foaming noise during cleaning after the molding of the foamed article is completed.
- the physical foaming agent introduction filter of the present invention is a physical foaming agent introduction filter used when introducing a physical foaming agent into a starved molten resin, Having a filter body and a plurality of fine holes penetrating the filter body in the thickness direction of the filter body, The fine holes are open on one surface side of the filter body and communicate with the resin contact side holes that are in contact with the molten resin, and open on the other surface side of the filter body and communicate with the resin contact side holes. and a physical foaming agent introduction hole into which the physical foaming agent is introduced,
- the diameter of the resin contact side hole is equal to or smaller than the diameter of the physical blowing agent introduction hole and is 10 to 80 ⁇ m.
- the reason why the diameter of the resin contact side hole is specified to be 10 to 80 ⁇ m is that it is technically difficult to form the resin contact side hole with a diameter of less than 10 ⁇ m. This is because the resin-contacting side hole is likely to be blocked by intruding into the side hole and hardening.
- the diameter of the resin contact side hole of the filter for introducing the physical blowing agent is equal to or less than the diameter of the physical blowing agent introduction hole and is 10 to 80 ⁇ m. can be suppressed. Therefore, the molten resin does not harden and remain in the introduction port provided with the filter for introducing the physical foaming agent. Also, the physical blowing agent can be reliably introduced into the starved molten resin from the physical blowing agent introduction hole through the resin contact side hole. Therefore, it is possible to suppress vent-up and stably supply the physical foaming agent to the starved molten resin.
- the physical blowing agent introduction hole may have a diameter of 20 to 400 ⁇ m.
- the reason why the diameter of the physical blowing agent introduction hole is specified to be 20 to 400 ⁇ m is that if the diameter of the physical blowing agent introduction hole is less than 20 ⁇ m, the passage of the physical blowing agent deteriorates, and the starved molten resin is physically foamed. This is because it becomes difficult to reliably introduce the agent, and if the diameter exceeds 400 ⁇ m, the diameter of the physical blowing agent introduction holes becomes too large, and the number of the physical blowing agent introduction holes decreases.
- the physical foaming agent can be reliably and stably introduced into the starved molten resin.
- a plurality of the fine holes are provided in the vertical and horizontal directions at predetermined intervals, and partition walls between the physical foaming agent introduction holes adjacent in the vertical direction and the physical foaming agent introduction holes adjacent in the horizontal direction
- the thickness of the partition between them may be 0.01-1.0 mm.
- the reason why the thickness of the partition wall between the physical foaming agent introduction holes adjacent to each other in the vertical direction and the horizontal direction is specified to be 0.01 to 1.0 mm is that if the thickness of the partition wall is less than 0.01 mm, the partition wall If the thickness of is too thin, the strength of the filter for introducing the physical blowing agent will decrease, and if it exceeds 1.0 mm, the thickness of the partition wall will be too thick and the number of holes for introducing the physical blowing agent will decrease.
- the apparatus for producing a foam molded article of the present invention has a plasticization zone in which a thermoplastic resin is plasticized and melted to become a molten resin, and a starvation zone in which the molten resin is in a starvation state.
- a plasticizing cylinder provided with an introduction port for a foaming agent; an introduction speed adjusting container connected to the introduction port; a physical foaming agent supply mechanism connected to the introduction speed adjusting container and supplying a physical foaming agent to the plasticizing cylinder via the introduction speed adjusting container;
- the introduction port is provided with the filter for introducing the physical foaming agent, A pressurized fluid containing the physical blowing agent at a constant pressure is supplied to the introduction speed adjusting container, the pressurized fluid at the constant pressure is introduced from the introduction speed adjusting container into the starvation zone, and the starvation zone is set at the constant pressure.
- the starved molten resin is brought into contact with a pressurized fluid containing a physical blowing agent at the constant pressure, It is characterized in that the molten resin brought into contact with the pressurized fluid containing the physical foaming agent is molded into a foamed molding.
- the diameter of the resin contact side hole of the filter for introducing the physical blowing agent is equal to or less than the diameter of the physical blowing agent introduction hole and is 10 to 80 ⁇ m. can be suppressed. Therefore, the molten resin does not harden and remain in the introduction port provided with the filter for introducing the physical foaming agent. Also, the physical blowing agent can be reliably introduced into the starved molten resin from the physical blowing agent introduction hole through the resin contact side hole. Therefore, it is possible to suppress vent-up and stably supply the physical foaming agent to the molten resin in the starvation zone.
- the introduction speed adjusting container may be provided with an introduction port opening/closing mechanism capable of opening and closing the introduction port.
- the introduction port is opened by the inlet opening and closing mechanism, so that the physical foaming agent can be stably introduced into the molten resin in the starvation zone, and the foam molded body can be molded.
- the gas (physical foaming agent) accumulated in the introduction speed adjustment container is introduced into the plasticizing cylinder by closing the inlet by the inlet opening and closing mechanism. Therefore, it is possible to suppress the occurrence of loud bubbling noise.
- the method for producing a foamed molded article of the present invention has a plasticization zone in which a thermoplastic resin is plasticized and melted to become a molten resin, and a starvation zone in which the molten resin is in a starvation state, and physical foaming is performed in the starvation zone.
- a plasticizing cylinder provided with an inlet for introducing an agent; an introduction speed adjusting container connected to the introduction port;
- the manufacturing method is plasticizing and melting the thermoplastic resin into the molten resin in the plasticizing zone;
- a pressurized fluid containing the physical blowing agent at a constant pressure is supplied to the introduction speed adjusting container, the pressurized fluid at the constant pressure is introduced from the introduction speed adjusting container into the starvation zone, and the starvation zone is set at the constant pressure.
- the method includes molding the molten resin in contact with the pressurized fluid containing the physical foaming agent into a foamed molding.
- the diameter of the resin contact side hole of the filter for introducing the physical blowing agent is equal to or less than the diameter of the physical blowing agent introduction hole and is 10 to 80 ⁇ m. can be suppressed. Therefore, the molten resin does not harden and remain in the introduction port provided with the filter for introducing the physical foaming agent. Also, the physical blowing agent can be reliably introduced into the starved molten resin from the physical blowing agent introduction hole through the resin contact side hole. Therefore, it is possible to suppress vent-up and stably supply the physical foaming agent to the molten resin in the starvation zone.
- the introduction speed adjusting container is provided with an inlet opening/closing mechanism capable of opening and closing the inlet,
- the introduction port is opened by the introduction port opening/closing mechanism,
- the introduction port may be closed by the introduction port opening/closing mechanism.
- the introduction port is opened by the inlet opening and closing mechanism, so that the physical foaming agent can be stably introduced into the molten resin in the starvation zone, and the foam molded body can be molded.
- the gas (physical foaming agent) accumulated in the introduction speed adjustment container is introduced into the plasticizing cylinder by closing the inlet by the inlet opening and closing mechanism. Therefore, it is possible to suppress the occurrence of loud bubbling noise.
- a physical foaming agent to a starvation zone (a zone in which starved molten resin exists) by suppressing vent-up.
- a starvation zone a zone in which starved molten resin exists
- FIG. 1 which shows a first embodiment of the present invention, is a cross-sectional view of a schematic configuration of an extrusion manufacturing apparatus for a foam molded article. It is a schematic structure sectional drawing which shows an introductory speed control container equally. It is a flow chart which shows the extrusion manufacturing method of a foaming molding equally. The same shows a filter for introducing a physical foaming agent, (a) is a plan view, (b) is a bottom view, and (c) is a cross-sectional view taken along the line AA in (a). It is sectional drawing of the principal part of the filter for physical foaming agent introduction equally.
- FIG. 1 It is a bottom view of sectional drawing of the principal part of the filter for introducing a physical foaming agent. Similarly, deformation of fine holes is shown, (a) is a cross-sectional view of a first modified example, and (b) is a cross-sectional view of a second modified example. Similarly, it is a bottom view of a cross-sectional view of a main part showing a modification of the filter for introducing the physical foaming agent.
- 2 is a schematic configuration diagram showing an extrusion manufacturing apparatus for a foam molded article according to a second embodiment of the present invention
- 2 shows a second embodiment of the present invention
- (a) is a schematic cross-sectional view showing the introduction speed control container with the introduction hole open
- (b) is the introduction speed control container with the introduction hole closed.
- 2 is a schematic cross-sectional view showing the configuration of FIG.
- a foam molded article is manufactured using the manufacturing apparatus 1000 shown in FIG.
- the manufacturing apparatus 1000 mainly includes a plasticizing cylinder 210 in which a screw 20 is installed, a cylinder 100 which is a physical foaming agent supply mechanism for supplying the physical foaming agent to the plasticizing cylinder 210, and a mold provided with a mold.
- a clamping unit (not shown) and a control device (not shown) for controlling the operation of the plasticizing cylinder 210 and the mold clamping unit are provided.
- the molten resin that is plasticized and melted in the plasticizing cylinder 210 flows from right to left in FIG. Therefore, inside the plasticizing cylinder 210 of this embodiment, the right hand in FIG. 1 is defined as "upstream” or "rear”, and the left hand is defined as "downstream” or "forward".
- the plasticizing cylinder 210 has a plasticizing zone 21 in which the thermoplastic resin is plasticized and melted to become molten resin, and a starvation zone 23 downstream of the plasticizing zone 21 in which the molten resin starves.
- the “starvation state” is a state in which the molten resin does not fill the starvation zone 23 but does not fill the starvation zone 23 . Therefore, in the starvation zone 23, there exists a space other than the portion occupied by the molten resin.
- the plasticizing cylinder 210 is formed with an inlet 202 for introducing the physical foaming agent into the starvation zone 23, and the inlet 202 is connected with an introduction speed adjusting container (pressure adjusting container) 300. there is The cylinder 100 supplies the physical blowing agent to the plasticizing cylinder 210 through the introduction speed adjusting container 300 .
- the manufacturing apparatus 1000 has only one starvation zone 23, the manufacturing apparatus used in this embodiment is not limited to this.
- the starvation zone 23 and a plurality of inlets 202 formed therein are provided, and the physical foaming agent is introduced into the plasticizing cylinder 210 from the plurality of inlets 202.
- the manufacturing apparatus 1000 is an injection molding apparatus, the manufacturing apparatus used in this embodiment is not limited to this, and may be, for example, an extrusion molding apparatus.
- the rotation of the screw 20 in the plasticizing cylinder 210 plasticizes and melts the resin pellets, and the molten resin is sent to the front side in the plasticizing cylinder 210 . Further, the molten resin is sent to the front side in the plasticizing cylinder 210 by the rotation of the screw 20 .
- On the upper side surface of the plasticizing cylinder 210 there are, in order from the upstream side, a resin supply port 201 for supplying the thermoplastic resin to the cylinder 210 and an introduction port 202 for introducing the physical foaming agent into the plasticizing cylinder 210. is provided.
- a resin supply hopper 211 and a feed screw 212 are arranged in the resin supply port 201 , and an introduction speed adjusting container 300 is connected to the introduction port 202 .
- the plasticizing cylinder 210 has a plasticizing zone 21 provided upstream and a starvation zone 23 provided downstream.
- the plasticization zone 21 is a zone where the thermoplastic resin is plasticized and melted to become molten resin.
- Starvation zone 23 is a zone in which the molten resin is in a starvation state.
- the term “starvation state” refers to a state in which the molten resin does not fill the starvation zone 23 without filling it, or a state in which the density of the molten resin has decreased. Therefore, a space other than the portion occupied by the molten resin may exist within the starvation zone 23 .
- the plasticizing cylinder 210 has a plasticizing zone 21, a compression zone 22, a flow rate adjustment zone 25, a starvation zone 23, and a recompression zone 24 in order from upstream to downstream.
- the plasticization zone 21 is a zone where the thermoplastic resin is plasticized and melted to become the molten resin as described above.
- the compression zone 22 is a zone in which the thermoplastic resin is shear kneaded, plasticized and melted, and the molten resin is compressed.
- the starvation zone 23 is a zone in which the molten resin is in a starvation state as described above.
- the recompression zone 24 is the zone where the molten resin is recompressed. Note that the flow rate adjustment zone 25 will be described later.
- the plasticizing cylinder 210 is provided with the introduction port 202 as an opening for introducing the physical foaming agent into the starvation zone 23 as described above.
- An introduction speed adjusting container 300 is connected to the introduction port 202 .
- the cylinder 100 is connected to the introduction speed adjusting container 300 via a pressure reducing valve 151 , a pressure gauge 152 and an open valve 153 via a pipe 154 .
- the cylinder 100 supplies the physical foaming agent into the cylinder 210 through the introduction speed adjusting container 300 .
- a shut-off valve 28 that opens and closes when driven by an air cylinder is provided at the nozzle tip 29 of the plasticizing cylinder 210, so that the inside of the plasticizing cylinder 210 can be maintained at a high pressure.
- a mold (not shown) is in close contact with the tip of the nozzle 29, and molten resin is injected and filled from the tip of the nozzle 29 into a cavity formed by the mold.
- thermoplastic resin plasticize and melt a thermoplastic resin.
- a thermoplastic resin is plasticized and melted to form a molten resin (step S1 in FIG. 3).
- the thermoplastic resin various resins can be used depending on the desired heat resistance and the use of the molded article.
- a crystalline resin is particularly desirable because it facilitates the formation of fine cells.
- These thermoplastic resins may be used alone or in combination of two or more.
- thermoplastic resins it is also possible to use those obtained by kneading these thermoplastic resins with various inorganic fillers such as glass fiber, talc, carbon fiber, and ceramics, and organic fillers such as cellulose nanofiber, cellulose, and wood powder.
- the thermoplastic resin is preferably mixed with an inorganic filler or organic filler that functions as a foam nucleating agent, or an additive that increases melt tension. By mixing these, foamed cells can be made finer.
- the thermoplastic resin may contain various general-purpose additives as necessary.
- thermoplastic resin is plasticized and melted in the plasticizing cylinder 210 in which the screw 20 is installed.
- a band heater (not shown) is provided on the outer wall surface of the plasticizing cylinder 210, which heats the plasticizing cylinder 210 and further adds shear heat generated by the rotation of the screw 20 to plasticize the thermoplastic resin. It is designed to melt.
- Step S2 in FIG. 3 a constant pressure physical foaming agent is supplied to the introduction speed adjusting container 300, a constant pressure pressurized fluid is introduced from the introduction speed adjusting container 300 into the starvation zone 23, and the starvation zone 23 is maintained at the constant pressure.
- a pressurized fluid is used as a physical foaming agent.
- "fluid” means any one of liquid, gas, and supercritical fluid.
- the physical blowing agent is preferably carbon dioxide, nitrogen, or the like from the viewpoint of cost and environmental load. Since the pressure of the physical foaming agent of the present embodiment is relatively low, for example, from a cylinder 100 in which a fluid such as a nitrogen cylinder, a carbon dioxide cylinder, or an air cylinder is stored, the pressure is reduced to a constant pressure by the pressure reducing valve 151 and taken out. fluid can be used. In this case, the cost of the entire manufacturing apparatus can be reduced because the booster is not required.
- a fluid pressurized to a predetermined pressure may be used as a physical foaming agent.
- the physical blowing agent can be produced by the following method. First, nitrogen is purified through a nitrogen separation membrane while compressing atmospheric air with a compressor. Next, the purified nitrogen is pressurized to a predetermined pressure using a booster pump, a syringe pump, or the like to generate a physical foaming agent. Compressed air may also be used as a physical blowing agent. In this embodiment, the physical blowing agent and the molten resin are not subjected to forced shear kneading.
- the pressure of the physical blowing agent introduced into the starvation zone 23 is constant, and the pressure of the starvation zone 23 is maintained at the same constant pressure as the introduced physical blowing agent.
- the pressure of this physical foaming agent is preferably 0.5 MPa to 30 MPa, more preferably 1 MPa to 25 MPa, even more preferably 1 MPa to 15 MPa.
- the optimum pressure varies depending on the type of molten resin, but by setting the pressure of the physical foaming agent to 1 MPa or more, the amount of physical foaming agent necessary for foaming can be penetrated into the molten resin, and the pressure is 30 MPa or less. By doing so, the heat resistance of the foam molded product can be improved.
- the pressure of the physical foaming agent that pressurizes the molten resin is "constant" means that the fluctuation range of the pressure with respect to the predetermined pressure is preferably within ⁇ 20%, more preferably within ⁇ 10%. .
- the pressure in the starvation zone 23 is measured, for example, by a pressure sensor 27 provided at a position facing the introduction port 202 of the plasticizing cylinder 210 .
- the starvation zone 23 moves back and forth in the plasticizing cylinder 210 as the screw 20 advances and retreats, but the pressure sensor 27 shown in FIG. It is provided at a position existing within the zone 23 . Also, the position facing the inlet 202 is always within the starvation zone 23 . Therefore, although the pressure sensor 27 is not provided at the position facing the introduction port 202, the pressure indicated by the pressure sensor 27 and the pressure at the position facing the introduction port 202 are substantially the same.
- only the physical blowing agent is introduced into the starvation zone 23, but other pressurized fluids other than the physical blowing agent are simultaneously introduced into the starvation zone 23 to the extent that the effect of the present invention is not affected. may In this case, the pressurized fluid containing the physical blowing agent introduced into the starvation zone 23 has the constant pressure mentioned above.
- the physical foaming agent is supplied from the introduction port 202 to the starvation zone 23 from the cylinder 100 via the introduction speed adjusting container 300 .
- the physical foaming agent is decompressed to a predetermined pressure using the decompression valve 151, and then introduced into the starvation zone 23 from the inlet 202 without passing through a booster or the like.
- the introduction amount of the physical foaming agent introduced into the plasticizing cylinder 210, introduction time, etc. are not controlled. Therefore, a mechanism for controlling them, for example, a driven valve using a check valve, an electromagnetic valve, or the like is not required, and the introduction port 202 does not have a driven valve and is always open.
- the pressure of the physical foaming agent supplied from the cylinder 100 is kept constant from the decompression valve 151 through the introduction speed adjusting container 300 to the starvation zone 23 in the plasticizing cylinder 210. be.
- the introduction port 202 of the physical foaming agent has a larger inner diameter D1 than the introduction port of the physical foaming agent of the conventional manufacturing apparatus. Therefore, even a relatively low-pressure physical foaming agent can be efficiently introduced into the plasticizing cylinder 210 . Further, even if part of the molten resin contacts the inlet 202 and solidifies, the inner diameter D1 is large, so the inlet can function as an inlet without being completely blocked. For example, when the inner diameter of the plasticizing cylinder 210 is large, that is, when the outer diameter of the plasticizing cylinder 210 is large, it is easy to increase the inner diameter D1 of the introduction port 202 .
- the inner diameter D1 of the introduction port 202 is 20% of the inner diameter of the plasticizing cylinder 210. ⁇ 100% is preferred, and 30% to 80% is more preferred.
- the inner diameter D1 of the introduction port 202 is preferably 3 mm to 150 mm, more preferably 5 mm to 100 mm.
- the inner diameter D1 of the introduction port 202 means the inner diameter of the opening on the inner wall 210a of the plasticizing cylinder 210, as shown in FIG.
- the shape of the inlet 202 that is, the shape of the opening on the inner wall 210a of the plasticizing cylinder 210 is not limited to a perfect circle, and may be an ellipse or a polygon.
- the diameter of a perfect circle having the same area as the area of the introduction port 202 is defined as the "inner diameter D1 of the introduction port 202".
- the introduction speed adjusting container 300 has the function of making the pressure of the physical foaming agent and the pressure of the starvation zone 23 in the plasticizing cylinder 210 the same constant pressure and maintaining the starvation zone 23 at the constant pressure. For example, when a large amount of the physical blowing agent is consumed in the starvation zone 23, the physical blowing agent may not be supplied in time and the pressure in the starvation zone 23 may decrease rapidly. It becomes possible to supply stably, and pressure fluctuations in the starvation zone 23 can be suppressed.
- the introduction speed adjusting container 300 is formed to have a volume equal to or larger than a certain level, and the flow speed of the physical foaming agent introduced into the plasticizing cylinder 210 is moderated, so that the physical foaming agent stays in the introduction speed adjusting container 300. Time is reserved.
- the introduction speed control vessel 300 is directly connected to a plasticizing cylinder 210 which is heated by a band heater (not shown) located around the circumference, and the heat of the plasticization cylinder 210 is also conducted to the introduction speed control vessel 300.
- the physical foaming agent inside the introduction speed adjusting container 300 is heated, the temperature difference between the physical foaming agent and the molten resin is reduced, and the temperature of the molten resin with which the physical foaming agent contacts is suppressed from being extremely lowered. and the amount of physical foaming agent dissolved in the molten resin (permeation amount) is stabilized. That is, the introduction speed adjusting container 300 functions as a buffer container having a function of heating the physical foaming agent. On the other hand, if the volume of the introduction speed adjusting container 300 is too large, the cost of the entire apparatus increases.
- the volume of the introduction speed adjusting container 300 depends on the amount of molten resin existing in the starvation zone 23, but is preferably 5 mL to 20 L, more preferably 10 mL to 2 L, even more preferably 10 mL to 1 L. By setting the volume of the introduction speed adjusting container 300 within this range, it is possible to secure the time for the physical foaming agent to stay while considering the cost.
- the physical foaming agent is consumed in the plasticizing cylinder 210 by contacting and permeating the molten resin.
- the consumed physical blowing agent is introduced into the starvation zone 23 from the introduction rate adjusting container 300 . If the volume of the introduction speed adjusting container 300 is too small, the replacement frequency of the physical blowing agent becomes high, so the temperature of the physical blowing agent becomes unstable, and as a result, there is a possibility that the supply of the physical blowing agent becomes unstable. Therefore, it is preferable that the introduction speed adjusting container 300 has a volume capable of retaining the amount of physical foaming agent consumed in the plasticizing cylinder 210 for 1 to 10 minutes.
- the volume of the introduction speed adjusting container 300 is preferably 0.1 to 5 times, more preferably 0.5 to 2 times, the volume of the starvation zone 23 to which the introduction speed adjusting container 300 is connected.
- the volume of the starvation zone 23 is defined as the region where the portion of the empty plasticizing cylinder 210 that does not contain the molten resin, where the diameter of the shaft of the screw 20 and the depth of the screw flight are constant (starvation zone 23) volume.
- the introduction speed adjusting container 300 is mainly composed of a cylindrical container body 310, a connecting member 320 connecting the container body 310 to the plasticizing cylinder 210, and a lid 330 of the container body 310. Configured. One end of the tubular container body 310 is connected to the introduction port 202 via the connecting member 320 , and the starvation zone 23 of the plasticizing cylinder 210 and the internal space 312 are communicated via the introduction port 202 . A lid 330 is provided at the other end (the end opposite to the introduction port 202) of the cylindrical container body so that it can be opened and closed. A pipe 154 for supplying the physical foaming agent to the internal space 312 is connected to the container body 310 .
- the introduction speed adjusting container 300 When focusing on the shape of the internal space 312 of the introduction speed adjusting container 300, the introduction speed adjusting container 300 is connected to the introduction port 202 and has a cylindrical first straight portion 31 whose inner diameter does not change, A tapered portion 32 provided adjacent to the portion 31 and having an inner diameter that increases with increasing distance from the introduction port 202, and a tubular second straight portion 33 provided adjacent to the tapered portion 32 and having an unchanged inner diameter.
- the introduction speed adjusting container 300 has a first straight portion 31, which is a cylinder having a small inner diameter D1, and a second straight portion 33, which is a cylinder having a large inner diameter D2.
- the first straight portion 31 and the second straight portion 32 are arranged so that their axes are aligned on the same straight line m, and have a structure in which the tapered surface of the tapered portion 32 joins.
- the extending direction of the straight line m that coincides with the central axis of the first straight portion 31 and the second straight portion 33 coincides with the extending direction of the introduction speed adjusting container 300 having a cylindrical shape.
- the first straight portion 31 is configured by the connecting member 320
- the tapered portion 32 and the second straight portion 33 are configured by the container body 310 .
- the lid 330 is provided on the second straight portion 33 of the container body 310 so that it can be opened and closed. Lid 330 is preferably openable and closable by the operator without using a special tool.
- molding conditions are set in advance (setting of conditions).
- the number of revolutions of the feed screw 212 and the screw 20 are optimized, and it is confirmed whether a stable starvation state is created in the starvation zone 23 .
- the lid 330 can be opened and closed by a simple method without using a bolt, and the resin that has entered the introduction speed adjusting container 300 can be removed. By allowing the lid 330 to be manually opened and closed by the operator, the working efficiency of setting molding conditions is improved.
- the sealing mechanism of the lid 330 is arbitrary, a sealing mechanism with a built-in spring, a clutch-type high-pressure sealing mechanism, or the like can be used.
- a polyimide sealing member 331 with a built-in spring is used. The sealing member 331 is expanded by the gas pressure of the physical foaming agent staying in the internal space 312, and the sealing performance is enhanced.
- the material constituting the introduction speed adjusting container 300 is preferably pressure-resistant from the viewpoint of containing the pressurized fluid, promotes solidification of the molten resin on the wall surface, and suppresses the intrusion of the molten resin into the container. From the viewpoint of improving performance, it is preferable that the heat capacity is large, the temperature does not rise easily, and heat is easily removed from the adhering resin. Moreover, from the viewpoint of heating the physical foaming agent, it is preferable that the thermal conductivity is high and the heat from the container body 310 is easily transmitted. From these points of view, the introduction speed adjusting container 300 is preferably made of metal such as stainless steel (SUS). The connecting member 320 is also the same.
- SUS stainless steel
- the molten resin is made to flow to the starvation zone 23, and the molten resin is put into a starvation state in the starvation zone 23 (step S3 in FIG. 3).
- the starvation state is determined by the balance between the amount of molten resin sent from the upstream of the starvation zone 23 to the starvation zone 23 and the amount of molten resin sent from the starvation zone 23 to the downstream thereof. becomes.
- the molten resin is starved in the starvation zone 23 by providing the compression zone 22 in which the molten resin is compressed and the pressure increases upstream of the starvation zone 23 .
- the compression zone 22 is provided with a large-diameter portion 20A in which the diameter of the shaft of the screw 20 is made larger (thicker) than that of the plasticizing zone 21 located on the upstream side, and the screw flights are gradually shallowed.
- a sealing portion 26 is provided adjacent to the downstream side of 20A.
- the seal portion 26 has a large (thick) shaft diameter of the screw 20 like the large-diameter portion 20A, and is not provided with a screw flight.
- the large-diameter portion 20A and the seal portion 26 reduce the clearance between the inner wall of the plasticizing cylinder 210 and the screw 20, thereby reducing the amount of resin to be supplied downstream. can increase the flow resistance of Therefore, in this embodiment, the large-diameter portion 20A and the seal portion 26 are mechanisms that increase the flow resistance of the molten resin.
- the sealing portion 26 also has the effect of suppressing the backflow of the physical foaming agent, that is, the movement of the physical foaming agent from the downstream side to the upstream side of the sealing portion 26 .
- the resin flow rate supplied from the compression zone 22 to the starvation zone 23 decreases, the molten resin is compressed in the compression zone 22 on the upstream side, the pressure increases, and the starvation rate on the downstream side increases.
- Zone 23 is underfilled with molten resin (starved state).
- the screw 20 has a structure in which the shaft diameter of the portion located in the starvation zone 23 is smaller (thinner) and the screw flight is deeper than the portion located in the compression zone 22.
- the screw 20 has a structure in which the shaft diameter of the portion located there is smaller (thinner) and the screw flight is deeper over the entire starvation zone 23 compared to the portion located in the compression zone 22. is preferred. Furthermore, throughout the starvation zone 23, the shaft diameter of the screw 20 and the depth of the screw flight are preferably substantially constant. Thereby, the pressure in the starvation zone 23 can be kept substantially constant, and the starvation state of the molten resin can be stabilized. In this embodiment, the starvation zone 23 is formed in a portion of the screw 20 where the diameter of the shaft of the screw 20 and the depth of the screw flight are constant, as shown in FIG.
- the mechanism for increasing the flow resistance of the molten resin provided in the compression zone 22 is a mechanism for temporarily reducing the flow area through which the molten resin passes in order to limit the flow rate of the resin supplied from the compression zone 22 to the starvation zone 23. If there is, it is not particularly limited. Although both the large-diameter portion 20A of the screw and the seal portion 26 are used in this embodiment, only one of them may be used. Mechanisms for increasing the flow resistance other than the large-diameter portion 20A of the screw and the seal portion 26 include a structure in which screw flights are provided in the opposite direction to other portions, a labyrinth structure provided on the screw, and the like.
- the mechanism that increases the flow resistance of the molten resin may be provided on the screw as a separate member such as a ring from the screw, or may be provided integrally with the screw as part of the screw structure. If the mechanism for increasing the flow resistance of the molten resin is provided as a ring or the like, which is a separate member from the screw, the size of the clearance portion, which is the flow path of the molten resin, can be changed by changing the ring, so that the flow of the molten resin can be easily performed. There is an advantage that the magnitude of the flow resistance can be changed.
- a backflow prevention mechanism that prevents the molten resin from flowing back from the starvation zone 23 to the compression zone 22 upstream is provided between the compression zone 22 and the starvation zone 23.
- This also allows the molten resin to be starved in the starvation zone 23 .
- a seal mechanism such as a ring or steel ball that can be moved upstream by the pressure of the physical foaming agent can be used.
- the backflow prevention mechanism requires a drive unit, there is a risk of resin stagnation. Therefore, a mechanism that does not have a drive unit and increases flow resistance is preferable.
- the amount of thermoplastic resin supplied to the plasticizing cylinder 210 may be controlled. This is because if the amount of thermoplastic resin supplied is too large, it will be difficult to maintain the starvation state.
- a general-purpose feed screw 212 is used to control the amount of thermoplastic resin supplied.
- the rate of molten resin metering in the starvation zone 23 is greater than the plasticization rate in the compression zone 22 due to the limited supply of thermoplastic resin. As a result, the density of the molten resin in the starvation zone 23 is stably lowered, promoting the permeation of the physical foaming agent into the molten resin.
- the length of the starvation zone 23 in the flow direction of the molten resin is preferably long in order to secure the contact area and contact time between the molten resin and the physical blowing agent.
- the adverse effect that the length becomes long occurs. Therefore, the length of the starvation zone 23 is preferably 2 to 12 times the inner diameter of the plasticizing cylinder 210, more preferably 4 to 10 times.
- the length of starvation zone 23 preferably covers the full range of metering strokes in injection molding. That is, the length of the starvation zone 23 in the flow direction of the molten resin is preferably equal to or longer than the length of the metering stroke in injection molding.
- the screw 20 moves forward and backward as the molten resin is plasticized, metered, and injected.
- a mouth 202 can be located (formed) within the starvation zone 23 .
- no zone other than the starvation zone 23 will come to the position of the inlet 202 even if the screw 20 moves forward and backward during the production of the foam molding.
- the physical foaming agent introduced from the introduction port 202 is always introduced into the starvation zone 23 during the production of the foam molded product.
- the starvation zone 23 can be easily maintained at a constant pressure.
- the length of the starvation zone 23 is substantially the same as the length of the portion of the screw 20 where the shaft diameter and screw flight depth of the screw 20 are constant, as shown in FIG.
- a flow rate adjustment zone 25 is provided between the compression zone 22 and the starvation zone 23. Comparing the flow rate of the molten resin in the compression zone 22 upstream of the flow rate adjustment zone 25 and the flow rate of the molten resin in the starvation zone 23 downstream, the flow rate of the molten resin in the starvation zone 23 is faster.
- the present inventors provided a flow rate adjustment zone 25 as a buffer zone between the compression zone 22 and the starvation zone 23 to suppress this rapid change (increase) in the flow rate of the molten resin. The inventors have found that the foamability of the foamed molded product is improved.
- the physical blowing agent remaining in the introduction speed adjusting container 300 is supplied to the starvation zone 23 . This keeps the pressure in the starvation zone 23 at a constant pressure, and the molten resin continues to contact the physical blowing agent at constant pressure.
- the foamed molded article produced in the present embodiment has finer foam cells despite the fact that the physical foaming agent is used at a lower pressure than in the conventional molding method using a physical foaming agent.
- the production method of the present embodiment does not require control of the introduction amount of the physical foaming agent, the introduction time, etc., drive valves such as check valves and electromagnetic valves, and control mechanisms for controlling these are unnecessary. Equipment costs can be reduced.
- the physical foaming agent used in this embodiment has a lower pressure than the conventional physical foaming agent, the load on the apparatus is also small.
- the starvation zone 23 is kept at constant pressure all the time during the production of the foamed molding. That is, all steps of the method for producing a foam molded product are carried out while continuously supplying the physical blowing agent at a constant pressure in order to compensate for the consumed physical blowing agent in the plasticizing cylinder.
- the molten resin for the next shot is supplied during the injection process, the cooling process for the molded body, and the process for taking out the molded body.
- the next shot of molten resin is pressurized at a constant pressure by a physical foaming agent.
- a state in which the molten resin and the physical blowing agent at a constant pressure are always present and in contact is the plasticization weighing process.
- an injection process, a cooling process for the molded body, a take-out process, and the like, and one cycle of injection molding is performed.
- the molten resin and the physical blowing agent at a constant pressure are always present and in contact with each other in the plasticizing cylinder. is always pressurized at a constant pressure by a physical blowing agent.
- the molten resin contacted with the physical foaming agent is molded into a foam molding (step S5 in FIG. 3).
- the plasticizing cylinder 210 used in this embodiment has a recompression zone 24 located downstream of the starvation zone 23 and adjacent to the starvation zone 23 where the molten resin is compressed to increase pressure.
- the rotation of the plasticizing screw 20 causes the molten resin in the starvation zone 23 to flow to the recompression zone 24 .
- the molten resin containing the physical blowing agent is pressure regulated in the recompression zone 24, pushed forward of the plasticizing screw 20 and metered.
- the internal pressure of the molten resin pushed forward of the plasticizing screw 20 is controlled as screw back pressure by a hydraulic motor or an electric motor (not shown) connected to the rear of the plasticizing screw 20 .
- the internal pressure of the molten resin extruded forward of the plasticizing screw 20, that is, the screw back pressure is is preferably controlled to be about 1 to 6 MPa higher than the pressure in the starvation zone 23 which is kept constant.
- a check ring 50 is provided at the tip of the screw 20 so that the compressed resin in front of the screw 20 does not flow back to the upstream side. As a result, the pressure in the starvation zone 23 is not affected by the resin pressure in front of the screw 20 during metering.
- the method of forming the foam molded product is not particularly limited, and the molded product can be formed by injection foam molding, extrusion foam molding, foam blow molding, etc., for example.
- injection foam molding is performed by injecting and filling a weighed molten resin from a plasticizing cylinder 210 shown in FIG. 1 into a cavity (not shown) in a mold.
- the mold cavity is filled with molten resin with a filling capacity of 75% to 95% of the mold cavity volume, and the short shot method is used to fill the mold cavity while the bubbles expand.
- a core-back method may be used in which the mold cavity is filled with molten resin in a filling amount of 100% of the mold cavity volume, and then the cavity volume is expanded to cause foaming. Since the resulting foamed molded article has foamed cells inside, shrinkage of the thermoplastic resin during cooling is suppressed, sink marks and warpage are reduced, and a molded article with a low specific gravity can be obtained.
- the starved molten resin is brought into contact with the physical foaming agent under the constant pressure in the starvation zone 23 while the pressure in the starvation zone 23 is maintained at a constant pressure. This makes it possible to stabilize the amount of physical foaming agent dissolved in the molten resin (permeation amount) by a simple mechanism.
- the manufacturing apparatus 1000 of the present embodiment includes a physical foaming agent introduction filter 101 (hereinafter sometimes abbreviated as filter 101) according to the present invention.
- filter 101 is fitted in a folder 110 as shown in FIG.
- the filter 101 is formed in a disc shape, and has a thickness of about 2 to 3 mm and a diameter of about 30 mm.
- the folder 110 is formed in a cylindrical shape, and a ring-shaped fitting portion 110a is formed so as to protrude in the axial direction of the folder 110 from one end surface (lower end surface in FIG. 4(c)). is provided with an annular bottom surface 110b.
- the filter 101 is coaxially fitted inside the ring-shaped fitting portion 110a, and the bottom surface of the filter 101 is brought into contact with the bottom surface 110b, whereby the filter 101 is positioned and fixed to the fitting portion 110a. there is In this state, the surface of the filter 101 and the tip surface of the fitting portion 110a are flush with each other.
- a male screw portion 110 c is formed on the outer peripheral surface of the folder 110 .
- the diameter D1 of the introduction port 202 of the connecting member 320 is equal to the diameter of the folder 110, and a female screw portion 202c is formed at the lower end of the inner peripheral surface of the introduction port 202.
- the male threaded portion 110c of the folder 110 is screwed into the female threaded portion 202c of the inlet 202, so that the filter 101 is inserted through the folder 110. It is attached to the introduction port 202 .
- the lower end surface of the filter 101 and the lower end surface of the connecting member 320 are flush with each other, so that the filter 101 faces the starvation zone 23 of the plasticizing cylinder 210 .
- the filter 101 includes a disk-shaped filter body 102 and a large number (plurality) of fine holes provided through the filter body 102 in the thickness direction of the filter body 102. 103.
- the fine holes 103 open on one surface side of the filter body 102 and communicate with the resin contact side holes 103a that are in contact with the molten resin, and open on the other surface side of the filter body 102 and communicate with the resin contact side holes 103a. and a physical foaming agent introduction hole 103b into which the physical foaming agent is introduced.
- the filter 101 is formed of a metallic microporous material manufactured using a metal 3D printer. That is, as one method for manufacturing a three-dimensional model in a three-dimensional modeling apparatus for manufacturing a three-dimensional model made of metal, a so-called metal 3D printer, a powder layer is formed by uniformly spreading metal material powder, A predetermined irradiation area on the powder layer is irradiated with a laser beam or an electron beam to melt and solidify the material powder in the predetermined irradiation area, and sintered layers are stacked repeatedly to generate a three-dimensional model. Metal powder additive manufacturing is known.
- the filter body 102 while manufacturing the filter body 102 by the metal powder additive manufacturing method, a large number of micropores 103 having fat contact side holes 103a and physical foaming agent introduction holes 103b are formed.
- the filter 101 is not limited to being made of metal, and may be made of resin.
- the resin contact side hole 103a and the physical blowing agent introduction hole 103b are arranged coaxially, and the diameter of the resin contact side hole 103a is equal to or smaller than the diameter of the physical blowing agent introduction hole 103b. As shown in FIGS. 5 and 6, the diameter of the resin contact side hole 103a is less than the diameter of the physical blowing agent introduction hole 103b (for example, about half the diameter of the physical blowing agent introduction hole 103b). Also, the axial length of the resin contact side hole 103a is shorter than the axial length of the physical foaming agent introduction hole 103b.
- the diameter d1 of the resin contact side hole 103a is 10 to 80 ⁇ m, and the diameter d2 of the physical blowing agent introduction hole 103b is 20 to 400 ⁇ m.
- the reason why the diameter d1 of the resin contact side hole 103a is specified to be 10 to 80 ⁇ m is that it is technically difficult to form the resin contact side hole with a diameter of less than 10 ⁇ m, and if the diameter d1 exceeds 80 ⁇ m, This is because the molten resin intrudes into the resin contact side hole 103a and solidifies, making it easier for the resin contact side hole 103a to be blocked.
- the reason why the diameter d2 of the physical blowing agent introduction hole 103b is set to 20 to 400 ⁇ m is that if the diameter d2 of the physical blowing agent introduction hole is less than 20 ⁇ m, the passage of the physical blowing agent deteriorates, and the molten resin in starvation state is reached.
- the resin contact side hole 103a and the physical foaming agent introduction hole 103b have a circular cross-sectional shape in the present embodiment, but the cross-sectional shape is not limited to this. , a cloud shape, a star shape, or the like, and these may be appropriately mixed.
- the cross-sectional shape of the resin contact side hole 103a and the physical blowing agent introduction hole 103b is not circular, the diameter of the resin contact side hole 103a and the physical blowing agent introduction hole 103b is equal to that of the resin contact side hole 103a and the physical blowing agent introduction hole. It is defined as the diameter of a perfect circle with the same area as the cross section of 103b.
- the inner peripheral surfaces of the resin contact side hole 103a and the physical foaming agent introduction hole 103b are formed straight in the axial direction, but it is not limited to this.
- the inner peripheral surface of the physical foaming agent introduction hole 103b may be formed so as to be inclined with respect to the axial direction.
- the physical foaming agent introduction hole 103b is formed such that its diameter becomes smaller toward the resin contact side hole 103a.
- the inner peripheral surfaces of the physical foaming agent introduction hole 103b and the resin contact side hole 103a may be formed so as to be inclined with respect to the axial direction.
- the physical foaming agent introduction hole 103b is formed so that its diameter becomes smaller toward the resin contact side hole 103a side, and the diameter of the resin contact side hole 103a becomes farther from the physical foaming agent introduction hole 103b. formed to be smaller according to
- the diameter of the physical blowing agent introduction hole 103b is the maximum diameter on the entrance side into which the physical blowing agent is introduced, and in the case shown in FIG.
- the diameter of the agent introduction hole 103b is the maximum diameter on the entrance side into which the physical blowing agent is introduced, and the diameter of the resin contact side hole 103a is the maximum diameter on the entrance side adjacent to the physical blowing agent introduction hole 103b in the axial direction. .
- a plurality (a large number) of fine holes 103 are provided vertically and horizontally on the surface of the disk-shaped filter body 102 at predetermined intervals, and the pitch P1 between the fine holes 103, 103 adjacent to each other in the vertical direction.
- the pitch P2 between the fine holes 103, 103 adjacent to each other in the lateral direction is the same, the pitch P1 and the pitch P2 may be different.
- the thickness t1 of the partition wall between the vertically adjacent physical foaming agent introduction holes 103b, 103b and the thickness t2 of the partition wall between the laterally adjacent physical foaming agent introduction holes 103b, 103b are 0.5. 01 to 1.0 mm.
- the thicknesses t1 and t2 of the partition walls between the physical foaming agent introduction holes 103b and 103b adjacent to each other in the vertical and horizontal directions are set to 0.01 to 1.0 mm because the thicknesses t1 and t2 of the partition walls When t2 is less than 0.01 mm, the partition wall thicknesses t1 and t2 become too thin, and the strength of the physical foaming agent introduction filter 101 decreases. This is because the number of the physical foaming agent introduction holes 103b is reduced due to the excessive increase.
- a plurality of (many) fine holes 103 are arranged vertically and horizontally, but the present invention is not limited to this.
- they may be arranged in a zigzag manner, and may be arranged such that vertically adjacent physical foaming agent introduction holes 103b, 103b partially overlap each other in the vertical direction. By doing so, the number of micropores 103 per unit area can be increased.
- the thickness t3 of the partition wall between the obliquely adjacent physical foaming agent introduction holes 103b, 103b is less than the thickness t2 of the partition wall between the laterally adjacent physical foaming agent introduction holes 103b, 103b. Thin is preferred.
- the thickness t3 of the partition wall between the obliquely adjacent physical foaming agent introduction holes 103b, 103b is 0.01 to 1.0 mm.
- the diameter of the resin contact side hole 103a of the filter 101 for introducing the physical blowing agent is equal to or smaller than the diameter of the physical blowing agent introduction hole 103b and is 10 to 80 ⁇ m.
- the physical foaming agent can be reliably introduced into the molten resin in the starvation state (starvation zone 23) through the introduction hole 202 and the resin contact side hole 103a. Therefore, it is possible to suppress vent-up and stably supply the physical foaming agent to the molten resin in the starvation state (starvation zone 23).
- the diameter of the physical blowing agent introduction hole 103b is 20 to 400 ⁇ m, the physical blowing agent can be reliably and stably introduced into the molten resin in the starvation state (starvation zone 23).
- the partition wall t1 between the vertically adjacent physical foaming agent introduction holes 103b, 103b and the thickness t2 of the partition wall between the laterally adjacent physical foaming agent introduction holes 103b, 103b are 0.01 to 1. 0 mm, it is possible to sufficiently secure the number of physical blowing agent introduction holes 103b while suppressing a decrease in the strength of the physical blowing agent introduction filter 101 .
- a foam molded product was manufactured using the foam molded product manufacturing apparatus equipped with the physical foaming agent introduction filter 101 according to the present invention described above (Examples 1 to 5).
- foam molded articles were manufactured using a foam molded article manufacturing apparatus equipped with a filter for introducing a physical blowing agent, which is not the present invention (Comparative Examples 1 and 2).
- the pressure stability of the starvation zone and the maintenance cycle (the number of shots when one shot is taken to produce one foam molded article) were confirmed.
- a large number of maintenance cycles means that it is difficult for the molten resin to enter the introduction hole 202, and a foamed molded product can be manufactured for a long time without clogging with the resin.
- the diameter of the resin contact side hole is in the range of 10 to 80 ⁇ m, and the diameter of the physical blowing agent introduction hole is in the range of 20 to 400 ⁇ m, both of which are within the scope of the present invention.
- the diameter of the resin contact side hole is 0.1 mm (100 ⁇ m), and the diameter of the physical blowing agent introduction hole is 0.2 mm (200 ⁇ m). Outside the range, the physical blowing agent introduction hole diameter is within the scope of the present invention.
- the diameter of the resin contact side hole was 0.03 mm (30 ⁇ m), and the diameter of the physical blowing agent introduction hole was 0.5 mm (500 ⁇ m). , the diameter of the physical blowing agent introduction hole is outside the scope of the present invention.
- the pressure in the starvation zone can be stably maintained at a constant level, and the maintenance cycle can be lengthened. Therefore, it is possible to prevent the molten resin from entering the resin contact side hole and clogging the resin contact side hole.
- a physical blowing agent can be reliably introduced.
- the diameter of the resin contact side hole is 0.1 mm (100 ⁇ m), which is larger than those of Examples 1 to 5, so the molten resin enters the resin contact side hole and solidifies. , the pressure in the starvation zone cannot be kept stable and constant. Also, the maintenance cycle is about 500 shots, which is short.
- the diameter of the physical blowing agent introduction hole is 0.5 mm (500 ⁇ m), which is larger than that of Examples 1 to 5, so the number of physical blowing agent introduction holes (per unit area number) is reduced. For this reason, it becomes difficult to reliably introduce the physical blowing agent, and the pressure stability of the starvation zone is lower than in Examples 1-5.
- FIG. 9 is a cross-sectional view showing the introduction speed adjusting container 300 in the manufacturing apparatus of the second embodiment.
- the introduction speed adjusting container 300 is provided with an inlet opening/closing mechanism 250 that can open and close the inlet 202. This point will be described below. will be described, and the same reference numerals will be given to the same configurations as in the first embodiment, and the description thereof may be omitted.
- the gas in the plasticizing cylinder 210 is degassed during cleaning after completion of foam molding using the manufacturing apparatus 1000, the gas (physical foaming agent) accumulated in the introduction speed adjusting container 300 is released into the plasticizing cylinder. Since it is introduced into 210 all at once, there may be a loud gunshot sound.
- the inlet opening/closing mechanism 250 is provided to suppress this gunshot sound. The configuration of the inlet opening/closing mechanism 250 will be described below.
- the inlet opening/closing mechanism 250 includes an air cylinder 251 and a piston 252 provided in the air cylinder 251 .
- the air cylinder 251 is formed in a cylindrical shape, and the lower end is fixed to the upper surface of the lid 330 of the introduction speed adjusting container 300 .
- the piston 252 has a disk-shaped flange portion 252a capable of reciprocating in the axial direction of the air cylinder 251, and a piston rod having a base end portion (upper end portion in FIG. 9) fixed to the center portion of the lower surface of the flange portion 252a. 252b.
- a packing member 252c is attached to the outer peripheral portion of the flange portion 252a so as to come into close contact with the inner peripheral surface of the air cylinder 251 so as to be slidable in the axial direction.
- the air cylinder 251 can alternately take in and out compressed air above and below a flange portion 252a in the air cylinder 251, thereby allowing the flange portion 252a to reciprocate in the axial direction.
- a through-hole 330a is formed in the central portion of the lid 330 so that the piston rod 252b passes through it in the axial direction.
- a packing member 252d is attached to the outer peripheral portion of the piston rod 252b so as to be in close contact with the inner peripheral surface of the through hole 330a so as to be slidable in the axial direction.
- a plug member 253 for opening and closing the introduction hole 202 is provided integrally with the piston rod 252b at the tip (lower end in FIG. 9) of the piston rod 252b.
- the plug member 253 is formed in the shape of a truncated cone, and the outer peripheral surface is an inclined surface whose diameter decreases toward the tip (lower end).
- a connecting member 320 forming the introduction hole 202 is formed with a conical receiving surface 320a on the entrance side of the introduction hole 202 (upper end side in FIG. 9).
- the receiving surface 320a is an inclined surface whose diameter increases upward. This inclined surface and the inclined surface of the plug member 253 are inclined at the same angle with respect to the straight line m.
- the introduction port 202 is opened by the introduction port opening/closing mechanism 250,
- the physical foaming agent can be stably introduced into the molten resin in the starvation zone 23, and the introduction port 202 is closed and sealed by the introduction port opening/closing mechanism 250 when degassing from the plasticizing cylinder 210 after the molding of the foam molded body is completed.
- the gas (physical foaming agent) accumulated in the introduction speed adjusting container 300 is not introduced into the plasticizing cylinder 210, so that the generation of loud foaming noise can be suppressed.
- the inlet 202 is provided with the physical foaming agent introduction filter 101, but as described above
- the present invention may be applied to a manufacturing apparatus for a foam molded body in which the introduction hole 202 is not provided with the physical foaming agent introduction filter 101 .
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Abstract
Description
また、発泡体の成形終了後のクリーニング時等に、可塑化シリンダ内のガスを脱気すると、導入速度調整容器に蓄積しているガス(物理発泡剤)が可塑化シリンダ内に一気に導入されるため、大きな発砲音がすることがある。
また、発泡体の成形終了後のクリーニング時等に大きな発泡音が生じるのを抑制できる発泡成形体の製造装置および製造方法を提供することを目的とする。
フィルタ本体と、このフィルタ本体に当該フィルタ本体の厚さ方向に貫通して設けられた複数の微細孔とを有し、
前記微細孔は、前記フィルタ本体の一方の表面側に開口して、前記溶融樹脂に接する樹脂接触側孔と、前記フィルタ本体の他方の表面側に開口し、かつ前記樹脂接触側孔と連通して、前記物理発泡剤が導入される物理発泡剤導入孔とを備え、
前記樹脂接触側孔は、直径が前記物理発泡剤導入孔の直径以下で、かつ10~80μmであることを特徴とする。
ここで、物理発泡剤導入孔の直径を20~400μmに規定したのは、物理発泡剤導入孔の直径が20μm未満では、物理発泡剤の通りが悪化して、飢餓状態の溶融樹脂に物理発泡剤を確実に導入し難くなり、400μmを超えると物理発泡剤導入孔の直径が大きくなりすぎて、物理発泡剤導入孔の数が減少するからである。
前記導入口に接続された導入速度調整容器と、
前記導入速度調整容器に接続され、前記導入速度調整容器を介して前記可塑化シリンダに物理発泡剤を供給する物理発泡剤供給機構とを有し、
前記導入口に前記物理発泡剤導入用フィルタが設けられ、
一定圧力の前記物理発泡剤を含む加圧流体を前記導入速度調整容器に供給し、前記導入速度調整容器から前記飢餓ゾーンに前記一定圧力の加圧流体を導入して、前記飢餓ゾーンを前記一定圧力に保持し、
前記飢餓ゾーンを前記一定圧力に保持した状態で、前記飢餓ゾーンにおいて、前記飢餓状態の溶融樹脂と前記一定圧力の物理発泡剤を含む加圧流体とを接触させ、
前記物理発泡剤を含む加圧流体を接触させた前記溶融樹脂を発泡成形体に成形することを特徴とする。
前記導入口に接続された導入速度調整容器と、
前記導入口に設けられた前記物理発泡剤導入用フィルタとを有する製造装置を用い、
前記製造方法は、
前記可塑化ゾーンにおいて、前記熱可塑性樹脂を可塑化溶融して前記溶融樹脂とすることと、
一定圧力の前記物理発泡剤を含む加圧流体を前記導入速度調整容器に供給し、前記導入速度調整容器から前記飢餓ゾーンに前記一定圧力の加圧流体を導入して、前記飢餓ゾーンを前記一定圧力に保持することと、
前記飢餓ゾーンにおいて、前記溶融樹脂を飢餓状態とすることと、
前記飢餓ゾーンを前記一定圧力に保持した状態で、前記飢餓ゾーンにおいて、前記飢餓状態の溶融樹脂と前記加圧流体とを接触させることと、
前記物理発泡剤を含む加圧流体を接触させた前記溶融樹脂を発泡成形体に成形することを含むこと特徴とする。
前記発泡成形体を成形する際は、前記導入口開閉機構によって前記導入口を開き、
前記発泡成形体の成形終了後に、前記可塑化シリンダから脱気する際に、前記導入口開閉機構によって前記導入口を閉じてもよい。
また、発泡体の成形終了後のクリーニング時等に大きな発泡音が生じるのを抑制できる。
第1の実施形態では、図1に示す製造装置1000を用いて発泡成形体を製造する。製造装置1000は、主に、スクリュ20が内設された可塑化シリンダ210と、物理発泡剤を可塑化シリンダ210に供給する物理発泡剤供給機構であるボンベ100と、金型が設けられた型締めユニット(不図示)と、可塑化シリンダ210及び型締めユニットを動作制御するための制御装置(不図示)を備える。
可塑化シリンダ210内において可塑化溶融された溶融樹脂は、図1における右手から左手に向かって流動する。したがって本実施形態の可塑化シリンダ210内部においては図1における右手を「上流」または「後方」、左手を「下流」または「前方」と定義する。
「飢餓状態」とは、溶融樹脂が飢餓ゾーン23内に充満せずに未充満となる状態である。したがって、飢餓ゾーン23内には、溶融樹脂の占有部分以外の空間が存在する。また、可塑化シリンダ210には、飢餓ゾーン23に物理発泡剤を導入するための導入口202が形成されており、導入口202には、導入速度調整容器(圧力調整容器)300が接続されている。ボンベ100は、導入速度調整容器300を介して可塑化シリンダ210に物理発泡剤を供給する。
可塑化シリンダ210の上部側面には、上流側から順に、熱可塑性樹脂をシリンダ210に供給するための樹脂供給口201、および物理発泡剤を可塑化シリンダ210内に導入するための導入口202が設けられている。
樹脂供給口201には、樹脂供給用のホッパー211、およびフィードスクリュ212が配設され、導入口202には、導入速度調整容器300が接続されている。
また、可塑化シリンダ210のノズル先端29には、エアシリンダの駆動により開閉するシャットオフバルブ28が設けられ、可塑化シリンダ210の内部を高圧に保持できる。ノズル先端29には金型(不図示)が密着し、金型が形成するキャビティ内にノズル先端29から溶融樹脂が射出充填される。
(1)熱可塑性樹脂を可塑化溶融する。
まず、可塑化シリンダ210の可塑化ゾーン21において、熱可塑性樹脂を可塑化溶融し、溶融樹脂とする(図3のステップS1)。熱可塑性樹脂としては、目的とする耐熱性や成形体の用途に応じて種々の樹脂を使用できる。
具体的には、例えば、ポリプロピレン、ポリメチルメタクリレート、ポリアミド、ポリエチレン、ポリカーボネート、ポリブチレンテレフタレート、アモルファスポリオレフィン、ポリエーテルイミド、ポリエチレンテレフタレート、ポリエーテルエーテルケトン、ABS樹脂(アクリロニトリル・ブタジエン・スチレン共重合樹脂)、ポリフェニレンスルファイド、シンジオタックポリスチレン、ポリアミドイミド、ポリ乳酸、ポリカプロラクトン等の熱可塑性樹脂、及びこれらの複合材料を用いることができる。特に結晶性樹脂が微細セルを形成しやすいので望ましい。これら熱可塑性樹脂は、単独で用いても、2種類以上を混合して用いてもよい。
また、これらの熱可塑性樹脂にガラス繊維、タルク、カーボン繊維、セラミック等の各種無機フィラー、セルロースナノファイバー、セルロース、木粉等の有機フィラーを混練したものを用いることもできる。熱可塑性樹脂には、発泡核剤として機能する無機フィラー、有機フィラーや溶融張力を高める添加剤を混合することが好ましい。これらを混合することで、発泡セルを微細化することができる。また、熱可塑性樹脂は、必要に応じてその他の汎用の各種添加剤を含むものであってもよい。
次に、一定圧力の物理発泡剤を導入速度調整容器300に供給し、導入速度調整容器300から飢餓ゾーン23に一定圧力の加圧流体を導入して、飢餓ゾーン23を前記一定圧力に保持する(図3のステップS2)。
なお、溶融樹脂を加圧する物理発泡剤の圧力が「一定である」とは、所定圧力に対する圧力の変動幅が、好ましくは±20%以内、より好ましくは±10%以内であることを意味する。飢餓ゾーン23の圧力は、例えば、可塑化シリンダ210の導入口202に対向する位置に設けられた圧力センサ27により測定される。
~100%が好ましく、30%~80%がより好ましい。または、可塑化シリンダ210の内径に依存せず、導入口202の内径D1は、3mm~150mmが好ましく、5mm~100mmがより好ましい。
ここで、導入口202の内径D1とは、図2に示すように、可塑化シリンダ210の内壁210a上における開口部の内径を意味する。また、導入口202の形状、即ち、可塑化シリンダ210の内壁210a上における開口部の形状は、真円に限られず、楕円や多角形であってもよい。導入口202の形状が楕円や多角形である場合には、導入口202の面積と同じ面積の真円におけるその直径を「導入口202の内径D1」と定義する。
次に、溶融樹脂を飢餓ゾーン23へ流動させ、飢餓ゾーン23において溶融樹脂を飢餓状態とする(図3のステップS3)。飢餓状態は、飢餓ゾーン23の上流から飢餓ゾーン23への溶融樹脂の送り量と、飢餓ゾーン23からその下流への溶融樹脂の送り量とのバランスで決定され、前者の方が少ないと飢餓状態となる。
なお、シール部26は、物理発泡剤の逆流、即ち、シール部26の下流側から上流側への物理発泡剤の移動を抑制する効果も奏する。
ある部分に形成される。
次に、飢餓ゾーン23を一定圧力に保持した状態で、飢餓ゾーン23において飢餓状態の溶融樹脂と一定圧力の前記物理発泡剤とを接触させる(図3のステップS4)。即ち、飢餓ゾーン23において、溶融樹脂を物理発泡剤により一定圧力で加圧する。飢餓ゾーン23は溶融樹脂が未充満(飢餓状態)であり物理発泡剤が存在できる空間があるため、物理発泡剤と溶融樹脂とを効率的に接触させることができる。溶融樹脂に接触した物理発泡剤は、溶融樹脂に浸透して消費される。物理発泡剤が消費されると、導入速度調整容器300中に滞留している物理発泡剤が飢餓ゾーン23に供給される。これにより、飢餓ゾーン23の圧力は一定圧力に保持され、溶融樹脂は一定圧力の物理発泡剤に接触し続ける。
化シリンダ内で準備されており、次のショット分の溶融樹脂が物理発泡剤により一定圧力で加圧される。つまり、連続で行う複数ショットの射出成形では、可塑化シリンダ内に、
溶融樹脂と一定圧力の物理発泡剤が常に存在して接触している状態、つまり、可塑化シリンダ内で溶融樹脂が物理発泡剤により一定圧力で常時、加圧された状態で、可塑化計量工程、射出工程、成形体の冷却工程、取り出し工程等を含む、射出成形の1サイクルが行われる。同様に、押出成形等の連続成形を行う場合にも、可塑化シリンダ内に、溶融樹脂と一定圧力の物理発泡剤が常に存在して接触している状態、つまり、可塑化シリンダ内で溶融樹脂が物理発泡剤により一定圧力で常時、加圧された状態で成形が行われる。
次に、物理発泡剤を接触させた溶融樹脂を発泡成形体に成形する(図3のステップS5)。本実施形態で用いる可塑化シリンダ210は、飢餓ゾーン23の下流に、飢餓ゾーン23に隣接して配置され、溶融樹脂が圧縮されて圧力が高まる再圧縮ゾーン24を有する。まず、可塑化スクリュ20の回転により、飢餓ゾーン23の溶融樹脂を再圧縮ゾーン24に流動させる。物理発泡剤を含む溶融樹脂は、再圧縮ゾーン24において圧力調整され、可塑化スクリュ20の前方に押し出されて計量される。このとき、可塑化スクリュ20の前方に押し出された溶融樹脂の内圧は、可塑化スクリュ20の後方に接続する油圧モータ又は電動モータ(不図示)により、スクリュ背圧として制御される。本実施形態では、溶融樹脂から物理発泡剤を分離させずに均一相溶させ、樹脂密度を安定化させるため、可塑化スクリュ20の前方に押し出された溶融樹脂の内圧、即ち、スクリュ背圧は、一定に保持されている飢餓ゾーン23の圧力よりも1~6MPa程度高く制御することが好ましい。尚、本実施形態では、スクリュ20前方の圧縮された樹脂が上流側に逆流しないように、スクリュ20の先端にチェックリング50が設けられる。これにより、計量時、飢餓ゾーン23の圧力は、スクリュ20前方の樹脂圧力に影響されない。
フィルタ101は円板状に形成され、厚さは2~3mm程度、直径は30mm程度に設定されている。
フォルダ110は円筒状に形成され、一方の端面(図4(c)において下端面)にはリング状の嵌合部110aがフォルダ110の軸方向に突出形成され、この嵌合部110aの底部には円環状の底面110bが設けられている。そして、リング状の嵌合部110aの内側にフィルタ101が同軸に嵌合されるとともに、フィルタ101の底面が底面110bに当接されることで、嵌合部110aにフィルタ101が位置決め固定されている。なお、この状態において、フィルタ101の表面と嵌合部110aの先端面とは面一となっている。
一方、図2に示すように、連結部材320の導入口202の直径D1はフォルダ110の直径と等しくなっており、導入口202の内周面の下端部には雌ねじ部202cが形成されている。
そして、フィルタ101を保持しているフォルダ110を導入口202に挿入したうえで、フォルダ110の雄ねじ部110cを導入口202の雌ねじ部202cに螺合することによって、フィルタ101がフォルダ110を介して導入口202に取り付けられている。この状態において、フィルタ101の下端面と連結部材320の下端面とは面一となっており、これによって、フィルタ101は可塑化シリンダ210の飢餓ゾーン23に面している。
微細孔103は、フィルタ本体102の一方の表面側に開口して、溶融樹脂に接する樹脂接触側孔103aと、フィルタ本体102の他方の表面側に開口し、かつ樹脂接触側孔103aと連通して、物理発泡剤が導入される物理発泡剤導入孔103bとを備えている。
すなわち、金属製の三次元造形物を製造する三次元造形装置、いわゆる金属3Dプリンタにおける三次元造形物の製造方法の1つとして、金属材料粉体を均一に撒布して粉末層を形成し、粉末層上の所定の照射領域にレーザ光または電子ビームを照射して所定の照射領域の材料粉体を溶融固化することを繰り返して焼結層を積層していき、三次元造形物を生成する金属粉末積層造形法が知られている。
本実施形態では、金属粉末積層造形法にフィルタ本体102を製造しながら、脂接触側孔103aと物理発泡剤導入孔103bとを備えた多数の微細孔103を形成する。
なお、フィルタ101は金属製に限らず樹脂製であってもよい。
また、樹脂接触側孔103aの直径d1は10~80μmであり、物理発泡剤導入孔103bの直径d2は20~400μmである。
また、物理発泡剤導入孔103bの直径d2を20~400μmに規定したのは、物理発泡剤導入孔の直径d2が20μm未満では、物理発泡剤の通りが悪化して、飢餓状態の溶融樹脂に物理発泡剤を確実に導入し難くなり、直径d2が400μmを超えると物理発泡剤導入孔103bの直径が大きくなりすぎて、物理発泡剤導入孔103bの数が減少するからである。
樹脂接触側孔103aおよび物理発泡剤導入孔103bの横断面形状が円形状以外の場合、樹脂接触側孔103aおよび物理発泡剤導入孔103bの直径は、樹脂接触側孔103aおよび物理発泡剤導入孔103bの横断面の面積と同じ面積の真円におけるその直径と定義する。
また、縦方向に隣り合う物理発泡剤導入孔103b,103bどうしの間の隔壁の厚さt1および横方向に隣り合う物理発泡剤導入孔103b,103bどうしの間の隔壁の厚さt2は0.01~1.0mmとなっている。
この場合、斜め方向に隣り合う物理発泡剤導入孔103b,103bどうしの間の隔壁の厚さt3を、横方向に隣り合う物理発泡剤導入孔103b,103bどうしの間の隔壁の厚さt2より薄くするのが好ましい。また、斜め方向に隣り合う物理発泡剤導入孔103b,103bどうしの間の隔壁の厚さt3は0.01~1.0mmとなっている。
また、物理発泡剤を導入孔202から樹脂接触側孔103aを通して、飢餓状態(飢餓ゾーン23)の溶融樹脂に物理発泡剤を確実に導入できる。
したがって、ベントアップを抑制して物理発泡剤を飢餓状態(飢餓ゾーン23)の溶融樹脂に安定供給できる。
さらに、縦方向に隣り合う物理発泡剤導入孔103b,103bどうしの間の隔壁t1および横方向に隣り合う物理発泡剤導入孔103b,103bどうしの間の隔壁の厚さt2が0.01~1.0mmであるので、物理発泡剤導入用フィルタ101の強度低下を抑制しつつ、物理発泡剤導入孔103bの数を十分に確保できる。
上述した本発明に係る物理発泡剤導入用フィルタ101を備えた発泡成形体の製造装置を用いて発泡成形体を製造した(実施例1~5)。
一方、本発明でない物理発泡剤導入用フィルタを備えた発泡成形体の製造装置を用いて発泡成形体を製造した(比較例1~2)。
そして、実施例と比較例において、飢餓ゾーンの圧力安定性およびメンテサイクル(発泡成形体を1個製造する場合を1ショットとしたときのショット数)について確認した。メンテサイクルの数が大きということは、導入孔202に溶融樹脂が侵入し難くなって、樹脂による詰まりがなく、長時間発泡成形体を製造できることを意味する。
また、表1中の「飢餓ゾーンの圧力安定性」の項目において、「〇±3%(6%、5%、8%)」とは、飢餓ゾーンの圧力が、一定圧力〇に対して±3%(6%、5%、8%)の範囲内で安定的に保持されることを意味する。
結果を表1に示す。
これに対し、比較例1では、樹脂接触側孔の直径が0.1mm(100μm)、物理発泡剤導入孔の直径が0.2mm(200μm)であり、樹脂接触側孔の直径は本発明の範囲外、物理発泡剤導入孔の直径は本発明の範囲内である。
また、比較例2では、樹脂接触側孔の直径は0.03mm(30μm)、物理発泡剤導入孔の直径が0.5mm(500μm)であり、樹脂接触側孔の直径は本発明の範囲内、物理発泡剤導入孔の直径は本発明の範囲外である。
したがって、溶融樹脂が樹脂接触側孔に侵入して当該樹脂接触側孔が閉塞されるのを抑制できるとともに、物理発泡剤を物理発泡剤導入孔から樹脂接触側孔を通して、飢餓状態の溶融樹脂に物理発泡剤を確実に導入できる。
次に第2の実施形態について説明する。
図9は、第2の実施形態の製造装置における導入速度調整容器300を示す断面図である。
第2の実施形態が第1の実施形態と異なる点は、導入速度調整容器300に、導入口202を開閉可能とする導入口開閉機構250が設けられている点であるので、以下ではこの点について説明し、第1の実施形態と同一構成には同一符号を付してその説明を省略する場合がある。
導入口開閉機構250は、この発砲音を抑制するために設けられている。以下導入口開閉機構250の構成について説明する。
エアシリンダ251は円筒状に形成され、下端部が導入速度調整容器300の蓋330の上面に固定されている。
ピストン252は、エアシリンダ251を軸方向に往復動可能な円板状のフランジ部252aと、このフランジ部252aの下面中央部に、基端部(図9において上端部)が固定されたピストンロッド252bとを備えている。また、フランジ部252aの外周部にはエアシリンダ251の内周面に軸方向に摺動可能に密接するパッキン部材252cが取り付けられている。
エアシリンダ251は、当該エアシリンダ251内のフランジ部252aより上側と下側に圧縮エアを交互に出し入れ可能となっており、これによって、フランジ部252aが軸方向に往復動可能となっている。
一方、導入孔202を形成する連結部材320には、導入孔202の入口側(図9において上端側)に円錐面状の受面320aが形成されている。受面320aは上方に向かうにしたがって拡径するような傾斜面となっている。この傾斜面と栓部材253の傾斜面とは直線mに対して等しい角度で傾斜している。
一方、図9(b)に示すように、ピストン252が押し出された状態、つまりフランジ部252aがエアシリンダ251の内部下面側に位置している状態では、栓部材253は、導入孔202に入り込んで、当該栓部材253の外周面が前記受面320aに密接して導入孔202を封止する。
23 飢餓ゾーン
100 ボンベ(物理発泡剤供給機構)
101 フィルタ
102 フィルタ本体
103 微細孔
103a 樹脂接触側孔
103b 物理発泡剤導入孔
202 導入口
210 可塑化シリンダ
250 導入口開閉機構
300 導入速度調整容器
1000 製造装置
Claims (7)
- 飢餓状態の溶融樹脂に物理発泡剤を導入する際に使用される物理発泡剤導入用フィルタであって、
フィルタ本体と、このフィルタ本体に当該フィルタ本体の厚さ方向に貫通して設けられた複数の微細孔とを有し、
前記微細孔は、前記フィルタ本体の一方の表面側に開口して、前記溶融樹脂に接する樹脂接触側孔と、前記フィルタ本体の他方の表面側に開口し、かつ前記樹脂接触側孔と連通して、前記物理発泡剤が導入される物理発泡剤導入孔とを備え、
前記樹脂接触側孔は、直径が前記物理発泡剤導入孔の直径以下で、かつ10~80μmであることを特徴とする物理発泡剤導入用フィルタ。 - 前記物理発泡剤導入孔の直径が20~400μmであることを特徴とする請求項1に記載の物理発泡剤導入用フィルタ。
- 前記微細孔が縦横に所定間隔で複数設けられ、縦方向に隣り合う前記物理発泡剤導入孔どうしの間の隔壁および横方向に隣り合う前記物理発泡剤導入孔どうしの間の隔壁の厚さは0.01~1.0mmであることを特徴とする請求項1または2に記載の物理発泡剤導入用フィルタ。
- 発泡成形体の製造装置であって、
熱可塑性樹脂が可塑化溶融されて溶融樹脂となる可塑化ゾーンと、前記溶融樹脂が飢餓状態となる飢餓ゾーンとを有し、前記飢餓ゾーンへの物理発泡剤の導入口が設けられた可塑化シリンダと、
前記導入口に接続された導入速度調整容器と、
前記導入速度調整容器に接続され、前記導入速度調整容器を介して前記可塑化シリンダに物理発泡剤を供給する物理発泡剤供給機構とを有し、
前記導入口に請求項1~3のいずれか1項に記載の物理発泡剤導入用フィルタが設けられ、
一定圧力の前記物理発泡剤を含む加圧流体を前記導入速度調整容器に供給し、前記導入速度調整容器から前記飢餓ゾーンに前記一定圧力の加圧流体を導入して、前記飢餓ゾーンを前記一定圧力に保持し、
前記飢餓ゾーンを前記一定圧力に保持した状態で、前記飢餓ゾーンにおいて、前記飢餓状態の溶融樹脂と前記一定圧力の物理発泡剤を含む加圧流体とを接触させ、
前記物理発泡剤を含む加圧流体を接触させた前記溶融樹脂を発泡成形体に成形することを特徴とする発泡成形体の製造装置。 - 前記導入速度調整容器に、前記導入口を開閉可能とする導入口開閉機構が設けられていることを特徴とする請求項4に記載の発泡成形体の製造装置。
- 発泡成形体の製造方法であって、
熱可塑性樹脂が可塑化溶融されて溶融樹脂となる可塑化ゾーンと、前記溶融樹脂が飢餓状態となる飢餓ゾーンとを有し、前記飢餓ゾーンに物理発泡剤を導入するための導入口が設けられた可塑化シリンダと、
前記導入口に接続された導入速度調整容器と、
前記導入口に設けられた請求項1~3のいずれか1項に記載の物理発泡剤導入用フィルタとを有する製造装置を用い、
前記製造方法は、
前記可塑化ゾーンにおいて、前記熱可塑性樹脂を可塑化溶融して前記溶融樹脂とすることと、
一定圧力の前記物理発泡剤を含む加圧流体を前記導入速度調整容器に供給し、前記導入速度調整容器から前記飢餓ゾーンに前記一定圧力の加圧流体を導入して、前記飢餓ゾーンを前記一定圧力に保持することと、
前記飢餓ゾーンにおいて、前記溶融樹脂を飢餓状態とすることと、
前記飢餓ゾーンを前記一定圧力に保持した状態で、前記飢餓ゾーンにおいて、前記飢餓状態の溶融樹脂と前記加圧流体とを接触させることと、
前記物理発泡剤を含む加圧流体を接触させた前記溶融樹脂を発泡成形体に成形することを含むこと特徴とする発泡成形体の製造方法。 - 前記導入速度調整容器に、前記導入口を開閉可能とする導入口開閉機構が設けられ、
前記発泡成形体を成形する際は、前記導入口開閉機構によって前記導入口を開き、
前記発泡成形体の成形終了後に、前記可塑化シリンダから脱気する際に、前記導入口開閉機構によって前記導入口を閉じることを特徴とする請求項6に記載の発泡成形体の製造方法。
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