WO2008054061A1 - Procédé de préparation de mousse microcellulaire avec un rapport de moussage uniforme et système d'extrusion et de moussage pour ce procédé - Google Patents

Procédé de préparation de mousse microcellulaire avec un rapport de moussage uniforme et système d'extrusion et de moussage pour ce procédé Download PDF

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Publication number
WO2008054061A1
WO2008054061A1 PCT/KR2007/004220 KR2007004220W WO2008054061A1 WO 2008054061 A1 WO2008054061 A1 WO 2008054061A1 KR 2007004220 W KR2007004220 W KR 2007004220W WO 2008054061 A1 WO2008054061 A1 WO 2008054061A1
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Prior art keywords
temperature
foam
zone
foaming
extrusion die
Prior art date
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PCT/KR2007/004220
Other languages
English (en)
Inventor
Jongsung Park
Kideog Choi
Kyunggu Nam
Original Assignee
Lg Chem, Ltd.
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Publication date
Application filed by Lg Chem, Ltd. filed Critical Lg Chem, Ltd.
Publication of WO2008054061A1 publication Critical patent/WO2008054061A1/fr

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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
    • B29C44/34—Auxiliary operations
    • B29C44/3469—Cell or pore nucleation
    • B29C44/348—Cell or pore nucleation by regulating the temperature and/or the pressure, e.g. suppression of foaming until the pressure is rapidly decreased
    • 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
    • B29C44/3415—Heating or cooling
    • B29C44/3419—Quick cooling
    • 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
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
    • B29C48/07—Flat, e.g. panels
    • 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
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/355—Conveyors for extruded 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
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/78—Thermal treatment of the extrusion moulding material or of preformed parts or layers, e.g. by heating or cooling
    • B29C48/86—Thermal treatment of the extrusion moulding material or of preformed parts or layers, e.g. by heating or cooling at the nozzle zone
    • 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
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/78—Thermal treatment of the extrusion moulding material or of preformed parts or layers, e.g. by heating or cooling
    • B29C48/86—Thermal treatment of the extrusion moulding material or of preformed parts or layers, e.g. by heating or cooling at the nozzle zone
    • B29C48/865—Heating
    • 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
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/78—Thermal treatment of the extrusion moulding material or of preformed parts or layers, e.g. by heating or cooling
    • B29C48/86—Thermal treatment of the extrusion moulding material or of preformed parts or layers, e.g. by heating or cooling at the nozzle zone
    • B29C48/87—Cooling
    • 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
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/78—Thermal treatment of the extrusion moulding material or of preformed parts or layers, e.g. by heating or cooling
    • B29C48/86—Thermal treatment of the extrusion moulding material or of preformed parts or layers, e.g. by heating or cooling at the nozzle zone
    • B29C48/872—Thermal treatment of the extrusion moulding material or of preformed parts or layers, e.g. by heating or cooling at the nozzle zone characterised by differential heating or cooling
    • 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
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/88—Thermal treatment of the stream of extruded material, e.g. cooling
    • B29C48/90—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article
    • 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
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
    • B29K2105/04—Condition, form or state of moulded material or of the material to be shaped cellular or porous

Definitions

  • the present invention relates to a method for preparing an uniform microcellular foam and an extruding system for the same. More particularly, the present invention relates to a method for preparing a microcellular foam, which includes mixing a thermoplastic polymer resin plasticized in an extruder with a foaming agent, melting the mixture and forming micro pores in the melted mixture while passing the mixture through a pressure drop zone of an extrusion die, and cooling the melted mixture formed with the micro pores while passing the melted mixture through a cooling zone of the extrusion die, and further includes setting the temperature at a downstream end of the pressure drop zone and the temperature at an upstream end of the cooling zone such that there is a temperature difference of 30 to 200 0 C between the temperatures, to extrude the mixture in the form of a microcellular foam, and pultruding the microcellular foam emerging from the extrusion die at a predetermined foam induction ratio by a pultrusion unit, to finely control the foaming ratio and time-dependent physical properties of the microcellular foam.
  • foams have many advantages of a thermal insulation property, a soundproof property, light weight, impact resistance, an electrical insulation property, optical characteristics, etc. Accordingly, such foams are widely used for various purposes in various fields associated with soundproof materials, insulating materials, cushioning materials, vibration-isolating materials, light reflection plates, light diffusion plates, etc.
  • Such foams are prepared using a foaming process such as a method in which a polymer resin is mechanically foamed or a method in which a resin compound containing a physical foaming agent or a chemical foaming agent is extrusion-molded to prepare a foam.
  • a foaming process such as a method in which a polymer resin is mechanically foamed or a method in which a resin compound containing a physical foaming agent or a chemical foaming agent is extrusion-molded to prepare a foam.
  • a foaming process such as a method in which a polymer resin is mechanically foamed or a method in which a resin compound containing a physical foaming agent or a chemical foaming agent is extrusion-molded to prepare a foam.
  • the physical foaming agent carbon dioxide, nitrogen, or hy- drofluoro carbon may be used.
  • a gas-producing organic material such as azodicarbon amide may be used.
  • the foaming process it is most important to control the size, shape, and quantitative distribution of pores.
  • the foaming process has many parameters, and has a difficulty to control conditions, as compared to other processes.
  • the properties of a foam may considerably depend on the foaming ratio of the foam. Accordingly, it is very important to adjust the foaming ratio.
  • the adjustment of the foaming ratio is achieved through adjustment of the content of a foaming agent or temperature adjustment.
  • the foaming ratio adjustment is roughly achieved in the unit of a very wide deviation range, for example, a 10% range such as 10%, 20%, ... For this reason, it is impossible to finely achieve the foaming ratio adjustment in the unit of a narrow deviation range, so that there is a limitation in adjusting the properties of the foam or uniformly adjusting the foaming ratio of the foam.
  • FIG. 1 is a schematic view illustrating an extruding and foaming system carrying out a general extruding and foaming process for preparation of a microcellular foam.
  • FIG. 2 illustrates a conventional extrusion die including only a pressure drop zone and a temperature variation occurring in the extrusion die, through an enlarged sectional view and a graph.
  • the extruding and foaming process is carried out through an extruder 10, an extrusion die 20, a calibration unit 30, a pultrusion unit 40, and a cutter 50 arranged in this order in an advancing direction of an extruded product.
  • the foamed extruded product emerging from the extrusion die 20 in a high-temperature state then passes through the calibration unit 30, in order to cool and solidify the foamed extruded product, and thus, to maintain the profile of the foamed extruded product.
  • the solidified product is cut into a desired length by the cutter 50 after passing through the pultrusion unit 40.
  • foams having a desired shape can be manufactured.
  • the extruded product which is fed to the calibration unit 30 after emerging from the extrusion die 20 in a high-temperature state, is exposed to atmospheric pressure at a relatively high-temperature state before being sufficiently cooled. For this reason, the extruded product is post-foamed by an internal foaming pressure thereof. Furthermore, the extruded product expands not only in an extrusion direction, but also in a width direction. As a result, since the foaming ratio of the foam varies with the lapse of time, there are severe problems in that the prepared foam may not have a desired foaming ratio, and may have a non-uniform cross-sectional shape.
  • the calibration unit 30 of the above-mentioned extruding/calibrating system which functions to cool an extruded product using a coolant circulated by a coolant circulator 31, has a very long processing length of about 3 to 6m. For this reason, there is a large spatial limitation caused by the calibration unit 30. Furthermore, the extrusion rate of the extruded product is about 3 to 5min/min when it passes through the calibration unit 30. For this reason, there is a limitation in increasing the pultrusion rate of the extruded product due to the calibration process, so that a great degradation in productivity occurs.
  • Japanese Patent Unexamined Publication No. 1997-057822 discloses a technique for detecting a frictional force generated between a foaming die and a resin foamed in the foaming die, and controlling a feeding rate of the resin, to prevent an extruded product from being surged due to a frictional force between an extrusion die and the extruded product, and thus, to prepare a foamed product having an uniform foaming ratio and a high dimension accuracy.
  • Unexamined Publication No. 1999-0063440 discloses a technique for preparing a foamed thermoplastic resin sheet having a large thickness and a high foaming magnitude.
  • an extrusion die is used which includes a foaming zone and a cooling zone.
  • the extrusion die also includes a pressure reducing chamber which can maintain a desired pressure reduction degree by a seal member, in order to achieve additional foaming, and thus to obtain a foam having a high foaming ratio.
  • the spacing between a pair of walls defining the pressure reducing chamber is adjusted.
  • the present invention provides a method for preparing a microcellular foam, comprising mixing a thermoplastic polymer resin plasticized in an extruder with a foaming agent, melting the mixture and forming micro pores in the melted mixture while passing the mixture through a pressure drop zone of an extrusion die, and cooling the melted mixture formed with the micro pores while passing the melted mixture through a cooling zone of the extrusion die, further comprising: setting the temperature at a downstream end of the pressure drop zone and the temperature at an upstream end of the cooling zone such that there is a temperature difference of 30 to 200 0 C between the temperatures, to extrude the mixture in the form of a microcellular foam; and pultruding the microcellular foam emerging from the extrusion die at a predetermined foam induction ratio by a pultrusion unit, to finely control the foaming ratio and time-dependent physical properties of the microcellular foam.
  • the microcellular foam preparing method comprises: (a) mixing a thermoplastic polymer resin plasticized in an extruder with a foaming agent, (b) melting the mixture and forming micro pores in the melted mixture while passing the mixture through a pressure drop zone of an extrusion die; (c) cooling the melted mixture formed with the micro pores while passing the melted mixture through a cooling zone of the extrusion die, and (d) pultruding the cooled microcellular foam emerging from the extrusion die at a predetermined foam induction ratio by a pultrusion unit, to finely control the foaming ratio and time-dependent physical properties of the microcellular foam.
  • the foaming process namely, the process for forming micro pores, (b)
  • the solidifying process for an extruded product namely, the process for cooling the extruded product, namely, the form, (c)
  • the foamed product extruded in a solidified state has a dense structure at the skin portion thereof due to an abrupt temperature variation occurring when the foamed product is extruded.
  • no expansion in a width direction occurs in the extruded product when the extruded product is exposed to atmospheric pressure.
  • Both the pressure drop zone and the cooling zone may be defined in a single extrusion die.
  • the pressure drop zone and cooling zone may be defined in separate block type extrusion dies, respectively.
  • the extrusion die includes a heater, in order to prevent a temperature decrease in the vicinity of the downstream end of the pressure drop zone.
  • the heater may be arranged inside the extrusion die.
  • the heater may be arranged inside and outside the extrusion die. There is no limitation on the heater.
  • a general electrical heater may be used for the heater.
  • the extrusion die includes a cooler, in order to prevent a temperature increase in the vicinity of the upstream end of the extrusion die.
  • the cooler may be formed inside the extrusion die, or may be formed inside and outside the extrusion die. There is no limitation on the cooler.
  • a pipe line through which a coolant flows, may be used for the cooler.
  • the temperature at the downstream end of the pressure drop zone can be appropriately adjusted in accordance with the kind of the raw material to be extruded. Preferably, this temperature is 150 to 25O 0 C. When the temperature at the downstream end of the pressure drop zone is less than 15O 0 C, it is difficult to sufficiently form micro pores. On the other hand, when the temperature is more than 25O 0 C, there may be a degradation of the thermoplastic resin and over-foaming of the thermoplastic resin. [30] The temperature at the upstream end of the cooling zone can be appropriately adjusted in accordance with the kind of the raw material to be extruded. Preferably, this temperature is 150 to 25O 0 C.
  • thermoplastic resin When the temperature at the downstream end of the pressure drop zone is less than 15O 0 C, it is difficult to sufficiently form micro pores. On the other hand, when the temperature is more than 25O 0 C, there may be a degradation of the raw material, namely, thermoplastic resin, and over-foaming of the thermoplastic resin.
  • the temperature at the upstream end of the cooling zone is maintained to be slightly higher than the melting point or softening point of the raw material to be extruded. More preferably, the temperature may be 40 to 15O 0 C.
  • the temperature at the upstream end of the cooling zone is less than 4O 0 C, an abrupt solidification occurs. In this case, it is difficult to execute the manufacturing process.
  • the temperature exceeds 15O 0 C the micro pores formed in the pressure drop zone are continuously grown even in the cooling zone. For this reason, it is difficult for the foam to have a skin layer having a sufficient thickness.
  • the temperature variation in each of the pressure drop zone and cooling zone is within +5 0 C. More preferably, the temperature variation is within +2 0 C. When the temperature variation is beyond the range of +5 0 C, it is impossible to obtain an uniformly-extruded product. In this case, the mechanical properties of the extruded product are degraded.
  • the transfer speed for the melted mixture formed with micro pores there is no specific limitation on the transfer speed for the melted mixture formed with micro pores.
  • the transfer speed is 0.5 to 20 m/min in terms of production efficiency.
  • a temperature transition zone is present between the pressure drop zone and the cooling zone.
  • the temperature transition rate in the temperature transition zone in a process advancing direction may be 2 to 40°C/mm, based on the following Expression (1).
  • T represents a temperature transition rate
  • T represents the t
  • the "temperature transition zone” means a zone where an abrupt temperature variation occurs between the pressure drop zone and the cooling zone. This temperature transition zone functions to prevent heat exchange occurring between the pressure drop zone and the cooling zone.
  • the temperature transition occurring in the temperature transition zone in a process advancing direction is referred to as a "temperature transition rate”.
  • the temperature transition zone has a higher temperature transition rate, the extruded product can be solidified at a higher density. Accordingly, it is more effective for the temperature transition zone to have a higher temperature transition rate in preparing an extruded product having superior surface characteristics.
  • the temperature transition rate is less than 2°C/mm, it is impossible to control formation of micro pores in the cooling zone.
  • the length of the temperature transition zone When the length of the temperature transition zone is reduced, an abrupt temperature variation may occur. Accordingly, it is preferred that the length of the temperature transition zone be 1 to 150 mm.
  • the foam induction ratio in the process (d) for pultruding the mi- crocellular foam at a predetermined foam induction ratio by the pultrusion unit, to finely control the foaming ratio and time-dependent physical properties of the mi- crocellular foam, it is possible to finely adjust the foam induction ratio by adjusting the linear velocity of the pultrusion unit in the unit of a fine range.
  • the "fine range” means a range corresponding to the unit of 10 (for example, the unit of 1%) or less. Accordingly, when the foam induction ratio is appropriately set, it is possible to prepare a microcellular foam having a desired foaming ratio with an allowable error range.
  • the foaming ratio can be adjusted within a control range of 0 to 80%.
  • the allowable error range of the foaming ratio in the finally-prepared foam in comparison with a desired foaming ratio may be ⁇ 0.5% or less.
  • the present invention can be widely used in fields in which it is necessary to finely and uniformly control the foaming ratio of a foam, for adjustment of the physical properties of the foam.
  • the foaming ratio variation occurring with the lapse of time is 0.1 to
  • the foam prepared in accordance with the method of the present invention exhibits no or little foaming ratio variation occurring with the lapse of time. Accordingly, it is possible to maintain the cross-sectional shape of the extruded product in spite of the lapse of time. Since the foam has an uniform foaming ratio, it has very uniform physical properties.
  • the thermoplastic polymer resin there is no specific limitation on the thermoplastic polymer resin, as long as the thermoplastic polymer resin is extradable.
  • the thermoplastic polymer resin polyethylene, acrylic resin, vinyl chloride resin, vinyl acetate resin, vinyl acetyl resin, polyamide resin, or celluloid resin may be used.
  • the thermoplastic polymer resin includes one or more polymers selected from the group consisting of acryl- butadiene-styrene (ABS) copolymer, polycarbonate (PC), polyvinyl chloride (PVC), polystyrene (PS), polymethylmethacrylate (PMMA), polyester, polypropylene, and nylon.
  • ABS acryl- butadiene-styrene
  • PC polycarbonate
  • PVC polyvinyl chloride
  • PS polystyrene
  • PMMA polymethylmethacrylate
  • polyester polypropylene
  • nylon nylon
  • the foaming agent there is no specific limitation on the foaming agent.
  • an inert gas may be used for the foaming agent.
  • carbon dioxide gas, nitrogen, or a mixture thereof may be used for the foaming agent.
  • the foaming agent is mixed in an amount of 3 to 0.1 weight % with 97 to 99.9 weight % of the thermoplastic resin.
  • the amount of the foaming agent is less than 0.1 weight %, foaming is insufficiently generated in the pressure drop zone. In this case, accordingly, it is impossible to form micro pores.
  • the amount of the foaming agent is more than 3 weight %, there is a residual foaming agent not dissolved in the thermoplastic resin.
  • the foaming agent it is desirable for the foaming agent to be mixed with the thermoplastic resin in a super-critical state.
  • the foaming agent When the foaming agent is mixed with a polymer resin in a super-critical state, it exhibits an increased miscibility to the polymer resin. In this case, accordingly, it is possible to form uniform pores in the resin, to reduce the size of the pores, and to increase the density of the pores.
  • a foaming agent which has already been in a super-critical state, may be used. Alternatively, the foaming agent may be changed into a super-critical state after being charged into the extruder.
  • the present invention also provides an extruding and foaming system including an extruder for plasticizing a mixture of a thermoplastic polymer resin and a foaming agent as described above, to extrude a foam, a pultrusion unit for pultruding the extruded foam at a predetermined speed, and a cutter for cutting the extruded foam into pieces having a certain length, wherein the extruder includes an extrusion die having a pressure drop zone and a cooling zone contiguous to the pressure drop zone, the temperature at a downstream end of the pressure drop zone and the temperature at an upstream end of the cooling zone are set such that there is a temperature difference of 30 to 200 0 C between the temperatures, to enable the extrusion die to extrude a mi- crocellular foam, and the pultrusion unit has a pultrusion speed set in accordance with a foam induction ratio, to finely control the foaming ratio and time-dependent physical properties of the microcellular foam.
  • the extruding and foaming system according to the present invention can cool and solidify a foam while simultaneously extruding the foam. Accordingly, it is possible to achieve an enhancement in extrusion rate. It is also possible to dispense with a calibration unit or to use only a calibration unit with a minimum processing length, and thus, to minimize the spatial waste of the system. In addition, a reduction in manufacturing costs and a great enhancement in production efficiency can be achieved.
  • the temperature at the downstream end of the pressure drop zone and the temperature at the upstream end of the cooling zone are set such that there is a temperature difference of 30 to 200 0 C between the temperatures, as described above. Due to such an abrupt temperature difference, the skin of the extruded product can be stably solidified in a dense state. As a result, there is no deformation of the extruded product even when there is an unsolidified portion at the central portion of the extruded product. Accordingly, it is unnecessary for the extruded product to pass through a calibration unit.
  • a calibration unit having a short processing length may be selectively arranged between the extruder and the pultrusion unit.
  • the calibration unit is configured to have a relatively short processing length.
  • the calibration unit may have a processing length of 3 m or less that is shorter than the processing length of a conventional calibration unit, namely, 3 to 6 m.
  • the calibration unit has a processing length of 2 m or less.
  • the present invention also provides a microcellular thermoplastic resin foam prepared in accordance with the above-described method.
  • a preferred example of the microcellular foam according to the present invention may have a structure including a skin layer thicker than that of a general microcellular foam, and a core layer formed with micro pores, as disclosed in Korean Patent Application No. 2005-115637. The content of this application is incorporated in the specification, for reference.
  • the microcellular foam according to the present invention can be used for interior and exterior materials for construction or optical reflection plates for display devices.
  • the microcellular foam is suitable for interior and exterior materials for construction.
  • the microcellular foam is suitable for interior and exterior materials for construction such as soundproof materials, insulating materials, construction materials, lightweight structural materials, packaging materials, electrical insulating materials, cushioning materials, or vibration- isolating materials.
  • FIG. 3 is a schematic view illustrating an extruding and foaming system carrying out an extruding and foaming process for preparation of a microcellular foam according to according to an embodiment of the present invention.
  • FIG. 4 illustrates an extrusion die included in the extruding and foaming system according to the embodiment of the present invention and a temperature variation occurring in the extrusion die, through an enlarged sectional view and a graph.
  • an extrusion process is executed through an extruding system in which an extruder 100, an extrusion die 200, a pultrusion unit 400, and a cutter 500 arranged in this order in an advancing direction of an extruded product.
  • thermoplastic resin is mixed with a foaming agent by an agitator 110, and the resultant mixture is then plasticized while passing through the extruder 100.
  • the resultant plasticized material is extruded in a melted state.
  • the extruded product is fed to the extrusion die 200, so as to have a certain shape.
  • micro pores are formed in the extruded product.
  • the extruded product is discharged out of the extrusion die 200 after being solidified while sequentially passing through a temperature transition zone 270 and a cooling zone 260, which are included in the extrusion die 200.
  • the temperature transition zone 270 has an abrupt temperature transition rate.
  • the cooling zone 260 is internally mounted with a cooler 230. After passing through the pultrusion unit 400 at a certain pultrusion speed, the extruded product is cut into a desired length by the cutter 500. Thus, desired extruded products are prepared.
  • the pultrusion speed of the pultrusion unit 400 is set in accordance with a desired foam induction ratio.
  • the extruded product emerges from the extrusion die 200 in a cooled and solidified state, and the temperature at the downstream end of the pressure drop zone and the temperature at the upstream end of the cooling zone are set such that there is a temperature difference of 30 to 200 0 C between the temperatures, a foam having a dense skin structure is formed in accordance with an abrupt temperature transition rate as the extruded product passes through the temperature transition zone 270. Accordingly, even when the extruded product is exposed to atmospheric pressure, there is no expansion in a width direction at the extruded product. As a result, the extruding system can be controlled to have a desired foam induction ratio in accordance with adjustment of the pultrusion speed of the pultrusion unit 400. Thus, it is possible to finely adjust the foaming ratio of the foam, and to uniformly control the foaming ratio of the foam such that the foam has a desired foaming ratio in spite of the lapse of time.
  • a calibration unit 300 may be arranged between the extrusion die 200 and the pultrusion unit 400. In this case, the extruded product emerging from the cooling zone 260 passes through the calibration unit 300.
  • the calibration unit 300 preferably has a short processing length of about 2 m or less.
  • a coolant circulator 310 is connected to the cooling zone 260 of the extrusion die 200 and/or the calibration unit 300. Accordingly, in accordance with circulation of a coolant, the extruded product can be cooled and solidified.
  • FIG. 1 is a schematic view illustrating an extruding and foaming system carrying out a general extruding and foaming process for preparation of a microcellular foam
  • FIG. 2 illustrates a conventional extrusion die including only a pressure drop zone and a temperature variation occurring in the extrusion die, through an enlarged sectional view and a graph
  • FIG. 6 illustrates a conventional extrusion die including only a pressure drop zone and a temperature variation occurring in the extrusion die, through an enlarged sectional view and a graph
  • FIG. 3 is a schematic view illustrating an extruding and foaming system carrying out an extruding and foaming process for preparation of a microcellular foam according to according to an embodiment of the present invention
  • FIG. 4 illustrates an extrusion die including a pressure drop zone, a temperature transition zone, and a cooling zone in accordance with the present invention and a temperature variation occurring in the extrusion die, through an enlarged sectional view and a graph.
  • An extrusion apparatus for extrusion-molding a thermoplastic resin was prepared by mounting an extrusion die having an integral structure constituted by a temperature- controllable high-temperature die as a foaming zone, a temperature transition zone, and a low-temperature die as a cooling zone to a bi-axial extruder, together with an adapter.
  • the high-temperature die had a length of 125 mm
  • the temperature transition zone had a length of 27 mm
  • the low-temperature die had a length of 40 mm.
  • Example 1 A PVC sheet was manufactured in the same manner as Example 1, except that a conventional extrusion die, which only includes a high-temperature die without including an extrusion die having an integral structure constituted by a temperature-controllable high-temperature die as a foaming zone, a temperature transition zone, and a low- temperature die as a cooling zone, and a cooling process was carried out using a calibration unit having a length of about 4m.
  • the conditions of the high-temperature die are described in the following Table 1.
  • the extrusion die is configured to have a predetermined processing condition such that a microcellular foam is extruded, and the extruded microcellular foam is pultruded at a predetermined foam induction ratio by the pultrusion unit. Accordingly, it is possible to finely adjust the foaming ratio of the microcellular foam and the physical properties of the microcellular foam exhibited with the lapse of time, and to maintain a desired cross-sectional shape of the microcellular foam in spite of the lapse of time. Since the system of the present invention may selectively include a calibration unit having a short processing length, it is possible to avoid a spatial waste of the extruding system and to reduce the manufacturing costs. As a result, the productivity can be highly enhanced.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Extrusion Moulding Of Plastics Or The Like (AREA)

Abstract

L'invention concerne un procédé de fabrication d'une mousse microcellulaire consistant à mélanger une résine polymère thermoplastique plastifiée dans une extrudeuse à un agent de moussage; à faire fondre le mélange et à former des micropores dans le mélange lors du passage du mélange au travers d'une zone de dépression d'un moule d'extrusion; et à refroidir le mélange fondu comportant les micropores lors du passage du mélange fondu au travers d'une zone de refroidissement du moule d'extrusion. L'invention concerne également un système capable de réaliser ledit procédé. Ledit procédé consiste par ailleurs à régler la température sur une extrémité aval de la zone de dépression et la température sur une extrémité amont de la zone de refroidissement de telle manière que la différence de température est de 30 à 2000 °C afin d'extruder le mélange sous forme de mousse microcellulaire; et à pultruder la mousse microcellulaire sortant du moule d'extrusion à un rapport de proportionnage de mousse prédéterminé au moyen d'une unité de pultrusion afin de commander précisément le rapport de moussage et les propriétés dépendant du temps de la mousse microcellulaire.
PCT/KR2007/004220 2006-10-30 2007-09-01 Procédé de préparation de mousse microcellulaire avec un rapport de moussage uniforme et système d'extrusion et de moussage pour ce procédé WO2008054061A1 (fr)

Applications Claiming Priority (2)

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KR10-2006-0105385 2006-10-30
KR1020060105385A KR100890159B1 (ko) 2006-10-30 2006-10-30 균일한 발포율의 미세 발포체를 제조하는 방법 및 이를위한 압출 발포 시스템

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EP2272647A1 (fr) * 2009-07-10 2011-01-12 Nordenia Technologies GmbH Procédé de fabrication d'une feuille extensible à monocouche ou multicouche
DE102010040775A1 (de) 2010-09-15 2012-03-15 Evonik Degussa Gmbh Fassadenplatte
WO2012035308A3 (fr) * 2010-09-16 2012-05-10 Massmelt Ltd Appareil et procédés de traitement des déchets
EP3162531A1 (fr) * 2015-10-30 2017-05-03 Technoform Tailored Solutions Holding GmbH Procédé de fabrication de profilés en mousse et profils de mousse pouvant être obtenus par le procédé
CN115056518A (zh) * 2022-07-19 2022-09-16 福建友和胶粘科技实业有限公司 一种pe泡棉胶带制造工艺

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TWI640414B (zh) * 2018-01-31 2018-11-11 蘇榮華 Plastic injection gas foaming pressure supply system

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JP2001206968A (ja) * 2000-01-25 2001-07-31 Mitsui Chemicals Inc 熱可塑性樹脂発泡体
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KR20000022976A (ko) * 1998-09-09 2000-04-25 베르너트로스텔,베르너스티레 두가지 이상의 색으로 채색된 포일, 배전반 포일, 계기판포일의 제작을 위한 방법 및 장치
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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2272647A1 (fr) * 2009-07-10 2011-01-12 Nordenia Technologies GmbH Procédé de fabrication d'une feuille extensible à monocouche ou multicouche
DE102010040775A1 (de) 2010-09-15 2012-03-15 Evonik Degussa Gmbh Fassadenplatte
WO2012034753A2 (fr) 2010-09-15 2012-03-22 Evonik Degussa Gmbh Panneau de façade
WO2012035308A3 (fr) * 2010-09-16 2012-05-10 Massmelt Ltd Appareil et procédés de traitement des déchets
US9956736B2 (en) 2010-09-16 2018-05-01 Massmelt Limited Waste processing apparatus and method
EP3162531A1 (fr) * 2015-10-30 2017-05-03 Technoform Tailored Solutions Holding GmbH Procédé de fabrication de profilés en mousse et profils de mousse pouvant être obtenus par le procédé
CN115056518A (zh) * 2022-07-19 2022-09-16 福建友和胶粘科技实业有限公司 一种pe泡棉胶带制造工艺
CN115056518B (zh) * 2022-07-19 2023-08-22 福建友谊胶粘带集团有限公司 一种pe泡棉胶带制造工艺

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KR100890159B1 (ko) 2009-03-25
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