WO2006002554A1 - Method for producing plastic parts, and casting or injection molding system for carrying out said method - Google Patents

Method for producing plastic parts, and casting or injection molding system for carrying out said method Download PDF

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Publication number
WO2006002554A1
WO2006002554A1 PCT/CH2004/000680 CH2004000680W WO2006002554A1 WO 2006002554 A1 WO2006002554 A1 WO 2006002554A1 CH 2004000680 W CH2004000680 W CH 2004000680W WO 2006002554 A1 WO2006002554 A1 WO 2006002554A1
Authority
WO
WIPO (PCT)
Prior art keywords
casting
injection molding
plastic parts
reactor
powder
Prior art date
Application number
PCT/CH2004/000680
Other languages
German (de)
French (fr)
Inventor
Michael John
Original Assignee
Ppal Ag
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ppal Ag filed Critical Ppal Ag
Publication of WO2006002554A1 publication Critical patent/WO2006002554A1/en

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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
    • B29C31/00—Handling, e.g. feeding of the material to be shaped, storage of plastics material before moulding; Automation, i.e. automated handling lines in plastics processing plants, e.g. using manipulators or robots
    • B29C31/04—Feeding of the material to be moulded, e.g. into a mould cavity
    • 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
    • B29C39/00—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor
    • B29C39/003—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor characterised by the choice of material
    • 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
    • B29C45/17—Component parts, details or accessories; Auxiliary operations
    • B29C45/18—Feeding the material into the injection moulding apparatus, i.e. feeding the non-plastified material into the injection unit
    • 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
    • B29C45/17—Component parts, details or accessories; Auxiliary operations
    • B29C45/18—Feeding the material into the injection moulding apparatus, i.e. feeding the non-plastified material into the injection unit
    • B29C2045/1883—Feeding the material into the injection moulding apparatus, i.e. feeding the non-plastified material into the injection unit directly injecting moulding material from the chemical production plant into the mould without granulating
    • 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
    • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
    • B29K2023/04—Polymers of ethylene
    • B29K2023/06—PE, i.e. polyethylene
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2031/00—Other particular articles
    • B29L2031/712—Containers; Packaging elements or accessories, Packages
    • B29L2031/7178—Pallets

Definitions

  • the present invention relates to processes for the production of plastic parts made of thermoplastic material. Furthermore, the invention relates to a casting or injection molding plant for carrying out this process.
  • plastic parts such as Kunststoffpalet ⁇ th
  • plastic granules are fed to the extruder an injection molding machine, after which it is molded in Spritzguss ⁇ forms thermoplastic to the desired plastic parts.
  • plastic granules already pass through an extruder in the plastics plant, in which, for example, the polyethylene powder originating from a preceding production section is extruded.
  • the thread-like intermediate product resulting from this process is cut into small pieces, cooled in a water bath, then dried and finally packaged as plastic granules in transportable containers.
  • This production section is the most expensive in the plastics industry. These costs are therefore disproportionately low, especially for simpler plastic parts.
  • the invention sets out to provide a process for the production of plastic parts and a casting or injection molding plant for carrying out this process, by which a simplification of the production process and thereby a reduction in manufacturing costs is achieved.
  • the inventive method for the production of plastic parts corresponds to the characterizing features of claim 1.
  • the casting or injection molding plant is apparent from claim 6. Further advantageous embodiments of the inventive concept can be seen from the dependent claims.
  • plastic parts can be produced by this method, provided that it does not depend on a particularly high tolerance accuracy.
  • relevant requirements such as those that are required of plastic pallets, are fully satisfied.
  • any other, in this respect simple plastic parts can be produced, for example, plastic containers or plastic dishes and the like.
  • the associated cost savings is just too startling.
  • the cost of the part of the production process resulting from the production of the raw material is less than half of the purchase price for plastic granules. They are even cheaper than the cost of procuring recycled materials. In the end, this means that, for example, a sales and ready-to-use plastic pallet is cheaper than the corresponding amount of plastic granules.
  • the single drawing figure shows schematically the manufacturing process and the facilities required for it.
  • the injection molding machine consisting essentially of an extruder and at least one injection molding station can be used, for example, in accordance with the method described in WO 01/02152. written injection molding machine to be designed.
  • the Anlagens ⁇ sections are explained below.
  • ethylene is fed to a flash tank 3 from a liquid gas tank 1 or from a gas tank 2.
  • the here ent ⁇ stretched, no longer liquid but gaseous ethylene is then fed by means of a pump 4 via a conduit system 5 to a reactor 6.
  • the resulting in the expansion tank 3 cold is used to cool the reactor 6 via a heat exchanger 7.
  • Forward and return are designated 8 and 9 respectively.
  • a cooling unit may be present. This can always be switched on if the self-cooling is insufficient.
  • the ethylene gas circulates in the reactor 6, whereby it is injected by injection of known catalysts, e.g. Titanium or magnesium catalysts, comes to a chemical reaction.
  • An injection device 10 serves to inject the catalysts.
  • the ethylene gas becomes PE polyethylene, which collects in powder form in the reactor 6.
  • the powder / gas mixture in the reactor 6 is conveyed at intervals into a separation tank 11, wherein the polyethylene powder is separated from the still remaining ethylene gas by gravity separation.
  • the latter is returned to the reactor 6 via a line system 12, which is preferably in connection with the first line system 5.
  • this insoluble polyethylene powder has been used in a first extruder to produce the plastic granulate used as material.
  • the polyethylene powder is hardly transportable and difficult to store. An ⁇ derem it has a ten times higher volume than the plastic granules, where it can not be compressed, for example by pressing, because this would create a solid block, which no longer process Hesse.
  • the previous reactors are extremely expensive, and therefore can not be used in plastics processing plants. These can thus Only use plastic granulate as material, which they obtain from a few large plastics plants.
  • the polyethylene powder falling from the separation tank 11 for example via conveyor belts or via another powder conveying device, is passed directly into the extruder 13 of the injection molding machine.
  • the additives or additives such as Farb ⁇ material, UV protection and flame retardant or other, also customized additives added.
  • foaming blowing agent is also added. This can be added only before the melt in the production section for forming the plastic parts.
  • this injection molding machine has, as is known in the art, at least one injection molding station 14, with a closing device carrying the injection molds, by means of which the injection molds are held in register during mold filling and cooling.
  • An injection device is connected to the injection molds for plastification and injection of the material.
  • the finished plastic does not undergo a heating process. Rather, it is, which is particularly advantageous, formed at the highest point of integrity directly to the desired plastic part. Although it is theo theoretically that plastic can be melted again. However, part of the strength is lost in each melting process. In the present case, this means that the saving of a second heating process markedly improves the quality of the plastic parts produced, despite significant cost savings. This method is particularly suitable where the same plastic parts with limited tolerance accuracy are always produced in large numbers. Mainly plastic parts made of PE, HDPE, LDPE or LPE are intended.
  • Polyethylene has excellent resistance to water, acids, alkalis and most organic solvents, and is easy to process by injection molding or casting.
  • a technically simpler and therefore affordable reactor 6 can be used, for example, for an annual output of 5 1 000 - 10 000 tonnes.
  • This can be designed specifically for processing the material specifically desired for the plastic parts to be produced, in particular with regard to its density and mixture.
  • the required reactor 6 can manage with only a few components, eg 5-10 instead of up to 350. Therefore, it is possible to realize a casting or injection molding system which is capable of producing a thermoplastic powder or polyethylene powder as material to use.
  • This casting or injection molding plant essentially comprises the devices shown in the drawing, but at least one reactor 6, an extruder 13 and, for example, one or more injection molding stations 14.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Robotics (AREA)
  • Manufacturing & Machinery (AREA)
  • Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
  • Injection Moulding Of Plastics Or The Like (AREA)
  • Extrusion Moulding Of Plastics Or The Like (AREA)

Abstract

The invention relates to a casting or injection molding system which comprises a reactor (6), a separation tank (11), an extruder (13) and at least one casting station or injection molding station (14). The plastic parts to be produced are shaped directly, i.e. without producing an intermediate product in the form of plastic granules, from the thermoplastic powder or polyethylene powder produced in the reactor (6). The plastic is therefore not subjected twice to a heating process. By avoiding a second heating process the quality of the plastic parts produced can be improved and costs reduced substantially. The inventive method is especially suitable for processes where the very same plastic parts are produced on a large scale and with limited tolerances, e.g. plastic pallets.

Description

Verfahren zur Herstellung von Kunststoffteilen und Guss- oder Spritzgussanlage zur Ausführung dieses Verfahrens.Process for the production of plastic parts and casting or injection molding plant for carrying out this process.
Die vorliegende Erfindung betrifft Verfahren zur Herstellung von Kunst¬ stoffteilen aus thermoplastischem Kunststoff. Weiter bezieht sich die Er¬ findung auf eine Guss- oder Spritzgussanlage zur Ausführung dieses Ver¬ fahrens.The present invention relates to processes for the production of plastic parts made of thermoplastic material. Furthermore, the invention relates to a casting or injection molding plant for carrying out this process.
Zur Herstellung von Kunststoffteilen, wie beispielsweise Kunststoffpalet¬ ten, wird nach dem gegenwärtigen Stand der Technik das allenfalls von einem entfernten Kunststoffwerk stammende Kunststoffgranulat dem Extruder einer Spritzgussmaschine zugeführt, wonach es in Spritzguss¬ formen thermoplastisch zu den gewünschten Kunststoffteilen geformt wird.For the production of plastic parts, such as Kunststoffpalet¬ th, according to the current state of the art, which originates from a distant plastic plant plastic granules are fed to the extruder an injection molding machine, after which it is molded in Spritzguss¬ forms thermoplastic to the desired plastic parts.
Das Kunststoffgranulat passiert indessen bereits im Kunststoffwerk einen Extruder, in dem beispielsweise das aus einem vorangegangenen Pro¬ duktionsabschnitt stammende Polyethylenpulver extrudiert wird. Das aus diesem Prozess hervorgehende, fadenförmige Zwischenprodukt wird in kleine Stücke geschnitten, in einem Wasserbad gekühlt, danach getrock¬ net und schliesslich als Kunststoffgranulat in transportfähige Gebinde ab¬ gepackt. Dieser Produktionsabschnitt ist in der Kunststoffherstellung der kostenintensivste. Diese Kosten schlagen sich daher insbesondere bei einfacheren Kunststoffteilen überproportional nieder.However, the plastic granules already pass through an extruder in the plastics plant, in which, for example, the polyethylene powder originating from a preceding production section is extruded. The thread-like intermediate product resulting from this process is cut into small pieces, cooled in a water bath, then dried and finally packaged as plastic granules in transportable containers. This production section is the most expensive in the plastics industry. These costs are therefore disproportionately low, especially for simpler plastic parts.
Auf der Grundlage dieser Erkenntnisse setzt sich die Erfindung die Aufga¬ be, ein Verfahren zur Herstellung von Kunststoffteilen und eine Guss¬ oder Spritzgussanlage zur Ausführung dieses Verfahrens zu schaffen, durch welche eine Vereinfachung des Produktionsprozesses und dadurch eine Verringerung der Herstellungskosten erreicht wird.On the basis of these findings, the invention sets out to provide a process for the production of plastic parts and a casting or injection molding plant for carrying out this process, by which a simplification of the production process and thereby a reduction in manufacturing costs is achieved.
Das erfindungsgemässe Verfahren zur Herstellung von Kunststoffteilen entspricht den kennzeichnenden Merkmalen des Patentanspruchs 1. Die Guss- oder Spritzgussanlage geht aus Patentanspruch 6 hervor. Weitere vorteilhafte Ausbildungen des Erfindungsgedankens sind aus den ab¬ hängigen Patentansprüchen ersichtlich.The inventive method for the production of plastic parts corresponds to the characterizing features of claim 1. The casting or injection molding plant is apparent from claim 6. Further advantageous embodiments of the inventive concept can be seen from the dependent claims.
Auf überraschende Weise hat sich gezeigt, dass sich durch dieses Ver¬ fahren gute Kunststoffteile herstellen lassen, sofern es dabei nicht auf eine besonders hohe Toleranzgenauigkeit ankommt. Den diesbezügli¬ chen Anforderungen, wie sie beispielsweise an Kunststoffpaletten zu stellen sind, wird aber vollauf Genüge getan. Selbstverständlich lassen sich auch beliebige andere, in dieser Hinsicht einfache Kunststoffteile herstellen, zum Beispiel Kunststoffbehälter oder auch Kunststoffgeschirr und dergleichen. Die damit einher gehende Kosteneinsparung ist gerade¬ zu verblüffend. Die Kosten des auf die Herstellung des Rohmaterials anfallenden Teils des Produktionsprozesses liegen unter der Hälfte des Einkaufspreises für Kunststoffgranulat. Sie sind sogar günstiger als die Beschaffungskosten für Recyclingmaterial. Im Endeffekt bedeutet dies, das beispielsweise eine Verkaufs- und gebrauchsfertige Kunststoffpalette günstiger ist, als die entsprechende Menge an Kunststoffgranulat.Surprisingly, it has been shown that good plastic parts can be produced by this method, provided that it does not depend on a particularly high tolerance accuracy. However, the relevant requirements, such as those that are required of plastic pallets, are fully satisfied. Of course, any other, in this respect simple plastic parts can be produced, for example, plastic containers or plastic dishes and the like. The associated cost savings is just too startling. The cost of the part of the production process resulting from the production of the raw material is less than half of the purchase price for plastic granules. They are even cheaper than the cost of procuring recycled materials. In the end, this means that, for example, a sales and ready-to-use plastic pallet is cheaper than the corresponding amount of plastic granules.
Nachfolgend wird ein bevorzugtes Ausführungsbeispiel der Erfindung an¬ hand der Zeichnung näher beschrieben.Hereinafter, a preferred embodiment of the invention will be described in detail an¬ hand of the drawing.
Die einzige Zeichnungsfigur zeigt schematisch das Herstellungsverfahren und die dafür benötigten Einrichtungen. Die im wesentlichen aus einem Extruder und mindestens einer Spritzguss-Station bestehende Spritzguss¬ maschine kann beispielsweise entsprechend der in WO 01/02152 be- schriebenen Spritzgussmaschine ausgestaltet werden. Die Verfahrens¬ abschnitte werden im folgenden erläutert.The single drawing figure shows schematically the manufacturing process and the facilities required for it. The injection molding machine consisting essentially of an extruder and at least one injection molding station can be used, for example, in accordance with the method described in WO 01/02152. written injection molding machine to be designed. The Verfahrens¬ sections are explained below.
Im vorliegenden Beispiel wird aus einem Flüssiggastank 1 oder aus einem Gastanker 2 Ethylen einem Entspannungstank 3 zugeführt. Das hier ent¬ spannte, nicht mehr flüssige sondern gasförmige Ethylen wird danach mit¬ tels einer Pumpe 4 über ein Leitungssystem 5 einem Reaktor 6 zugeleitet. Die im Entspannungstank 3 entstehende Kälte wird dazu benützt den Reaktor 6 über einen Wärmetauscher 7 zu kühlen. Vor- und Rücklauf sind mit 8 bzw. 9 bezeichnet. Für den Fall, dass diese Kälte nicht ausreicht, kann ein Kühlaggregat vorhanden sein. Dieses kann immer dann einge¬ schaltet werden, wenn die Eigenkühlung nicht ausreicht. Das Ethylengas zirkuliert im Reaktor 6, wobei es unter Einspritzung von bekannten Kata¬ lysatoren, z.B. Titan- oder Magnesiumkatalysatoren, zu einer chemischen Reaktion kommt. Zum Einspritzen der Katalysatoren dient eine Einspritz¬ einrichtung 10. Das Ethylengas wird zu PE Polyethylen, das sich pulver- förmig im Reaktor 6 sammelt. Das im Reaktor 6 befindliche Pulver-/Gas- gemisch wird in Intervallen in einen Trennungstank 11 befördert, wobei durch Gravitationstrennung das Polyethylenpulver vom noch verbliebenen Ethylengas getrennt wird. Letzteres wird über ein Leitungssystem 12, das vorzugsweise in Verbindung mit dem ersten Leitungssystem 5 steht, wieder dem Reaktor 6 zugeführt.In the present example, ethylene is fed to a flash tank 3 from a liquid gas tank 1 or from a gas tank 2. The here ent¬ stretched, no longer liquid but gaseous ethylene is then fed by means of a pump 4 via a conduit system 5 to a reactor 6. The resulting in the expansion tank 3 cold is used to cool the reactor 6 via a heat exchanger 7. Forward and return are designated 8 and 9 respectively. In the event that this cold is insufficient, a cooling unit may be present. This can always be switched on if the self-cooling is insufficient. The ethylene gas circulates in the reactor 6, whereby it is injected by injection of known catalysts, e.g. Titanium or magnesium catalysts, comes to a chemical reaction. An injection device 10 serves to inject the catalysts. The ethylene gas becomes PE polyethylene, which collects in powder form in the reactor 6. The powder / gas mixture in the reactor 6 is conveyed at intervals into a separation tank 11, wherein the polyethylene powder is separated from the still remaining ethylene gas by gravity separation. The latter is returned to the reactor 6 via a line system 12, which is preferably in connection with the first line system 5.
Bisher wurde dieses unlösliche Polyethylenpulver zur Herstellung des als Werkstoff dienenden Kunststoffgranulats in einen ersten Extruder gege¬ ben. Dies hat technische und wirtschaftliche Gründe. Zum einen ist das Polyethylenpulver kaum transportfähig und schlecht zu lagern. Unter an¬ derem weist es ein zehnmal höheres Volumen als das Kunststoffgranulat auf, wobei es sich nicht verdichten lässt, z.B. durch Pressen, denn dabei entstünde ein fester Block, der sich nicht mehr weiterverarbeiten Hesse. Andererseits sind die bisherigen Reaktoren extrem teuer, und daher in Kunststoff verarbeitenden Betrieben nicht einsetzbar. Diese können somit als Werkstoff nur Kunststoffgranulat verwenden, das sie von wenigen grossen Kunststoffwerken beziehen.To date, this insoluble polyethylene powder has been used in a first extruder to produce the plastic granulate used as material. This has technical and economic reasons. First, the polyethylene powder is hardly transportable and difficult to store. An¬ derem it has a ten times higher volume than the plastic granules, where it can not be compressed, for example by pressing, because this would create a solid block, which no longer process Hesse. On the other hand, the previous reactors are extremely expensive, and therefore can not be used in plastics processing plants. These can thus Only use plastic granulate as material, which they obtain from a few large plastics plants.
Erfindungsgemäss wird dagegen das aus dem Trennungstank 11 fallende Polyethylenpulver, beispielsweise über Transportbänder oder über eine andere Pulverfördereinrichtung, direkt in den Extruder 13 der Spritzguss¬ maschine geleitet. Erst dort werden die Additive, bzw. Zusätze, wie Farb¬ stoff, UV-Schutz und Flammschutz oder sonstige, auch kundenspezifi¬ sche Zusätze gegeben. Zum Schäumen wird darüber hinaus Treibmittel beigegeben. Dieses kann erst vor der Schmelze im Produktionsabschnitt zum Formung der Kunststoffteile hinzu gegeben werden.According to the invention, by contrast, the polyethylene powder falling from the separation tank 11, for example via conveyor belts or via another powder conveying device, is passed directly into the extruder 13 of the injection molding machine. Only there are the additives or additives such as Farb¬ material, UV protection and flame retardant or other, also customized additives added. For foaming blowing agent is also added. This can be added only before the melt in the production section for forming the plastic parts.
Im übrigen weist diese Spritzgussmaschine, wie technisch bekannt, min¬ destens eine Spritzguss-Station 14 auf, mit einer die Spritzgussformen tragenden Schliesseinrichtung, durch welche die Spritzgussformen wäh¬ rend der Formfüllung und Abkühlung in Passlage gehalten werden. An die Spritzgussformen ist eine Spritzeinrichtung angeschlossen, zum Plastifi- zieren und Einspritzen des Werkstoffs.Moreover, this injection molding machine has, as is known in the art, at least one injection molding station 14, with a closing device carrying the injection molds, by means of which the injection molds are held in register during mold filling and cooling. An injection device is connected to the injection molds for plastification and injection of the material.
Da als Werkstoff nicht wie bisher Kunststoffgranulat, sondern direkt das Polyethylenpulver dem Extruder 13 der Spritzgussmaschine zugeführt wird, muss der fertige Kunststoff keinen Aufheizprozess durchmachen. Vielmehr wird er, was besonders vorteilhaft ist, an der höchsten Stelle der Integrität direkt zum gewünschten Kunststoffteil geformt. Zwar ist es theo¬ retisch so, dass Kunststoff wieder schmelzbar ist. Bei jedem Schmelzvor¬ gang geht aber ein Teil der Festigkeit verloren. Im vorliegenden Fall be¬ deutet dies, dass durch die Einsparung eines zweiten Aufheizprozesses die Qualität der hergestellten Kunststoffteile, trotzt erheblicher Kostenein¬ sparung, merklich verbessert wird. Dieses Verfahren ist insbesondere dort geeignet, wo in grosser Anzahl immer gleiche Kunststoffteile mit beschränkter Toleranzgenauigkeit her¬ gestellt werden. Hauptsächlich ist dabei an Kunststoffteilen aus PE, bzw. HDPE, LDPE oder LPE gedacht. Polyethylen zeichnet sich durch eine ausgezeichnete Beständigkeit gegen Wasser, Säuren, Laugen und den meisten organischen Lösungsmitteln aus und lässt sich gut in Spritz- oder Giessverfahren verarbeiten. Bei diesem Verfahren kann ein technisch ein¬ facher und daher erschwinglicher Reaktor 6 verwendet werden, beispiels¬ weise für einen jährlichen Ausstoss von 51OOO - 10'0OO Tonnen. Dieser kann gezielt zur Verarbeitung des für die herzustellenden Kunststoffteile speziell gewünschten Werkstoffs ausgelegt werden, insbesondere hin¬ sichtlich dessen Dichte und Mischung. Dadurch kann der benötigte Reak¬ tor 6 mit nur wenigen Bauteilen auskommen, z.B. 5 - 10 anstatt bis zu 350. Es lässt sich daher eine Guss- oder Spritzgussanlage realisieren, die in der Lage ist, als Werkstoff ein thermoplastisches Pulver bzw. PoIy- ethylenpulver zu verwenden. Diese Guss- oder Spritzgussanlage beinhal¬ tet im wesentlichen die in der Zeichnung dargestellten Einrichtungen, zu¬ mindest aber einen Reaktor 6, einen Extruder 13 und beispielsweise eine oder mehrere Spritzguss-Stationen 14.Since the material is not supplied as plastic granules as before, but directly the polyethylene powder to the extruder 13 of the injection molding machine, the finished plastic does not undergo a heating process. Rather, it is, which is particularly advantageous, formed at the highest point of integrity directly to the desired plastic part. Although it is theo theoretically that plastic can be melted again. However, part of the strength is lost in each melting process. In the present case, this means that the saving of a second heating process markedly improves the quality of the plastic parts produced, despite significant cost savings. This method is particularly suitable where the same plastic parts with limited tolerance accuracy are always produced in large numbers. Mainly plastic parts made of PE, HDPE, LDPE or LPE are intended. Polyethylene has excellent resistance to water, acids, alkalis and most organic solvents, and is easy to process by injection molding or casting. In this method, a technically simpler and therefore affordable reactor 6 can be used, for example, for an annual output of 5 1 000 - 10 000 tonnes. This can be designed specifically for processing the material specifically desired for the plastic parts to be produced, in particular with regard to its density and mixture. As a result, the required reactor 6 can manage with only a few components, eg 5-10 instead of up to 350. Therefore, it is possible to realize a casting or injection molding system which is capable of producing a thermoplastic powder or polyethylene powder as material to use. This casting or injection molding plant essentially comprises the devices shown in the drawing, but at least one reactor 6, an extruder 13 and, for example, one or more injection molding stations 14.
Es liegt im Rahmen der Erfindung, das Verfahren und/oder die Guss¬ oder Spritzgussanlage im einzelnen auch anders als anhand des vor¬ gehenden Beispiels beschrieben auszuführen bzw. auszubilden. It is within the scope of the invention, the method and / or the Guss¬ or injection molding in detail differently than described with reference to vor¬ outgoing example or train.

Claims

Patentansprüche claims
1. Verfahren zur Herstellung von Kunststoffteilen aus thermoplastischem Kunststoff, dadurch gekennzeichnet, dass in einem Reaktor (6) gebilde¬ tes thermoplastisches Pulver einem Extruder (13) und danach als Werkstoff einer Guss- oder Spritzgussmaschine zugeführt wird, mit dem Zweck, aus diesem Pulver thermoplastisch die Kunststoffteile zu formen.1. A process for the production of plastic parts from thermoplastic material, characterized in that in a reactor (6) gebilde¬ tes thermoplastic powder is fed to an extruder (13) and thereafter as a material of a casting or injection molding machine, with the purpose of this powder thermoplastic to mold the plastic parts.
2. Verfahren nach Anspruch 1 , dadurch gekennzeichnet, dass Ethylen im Reaktor (6) zu pulverförmigem PE Polyethylen gewandelt wird, das z.B. unter Zwischenschaltung eines Trennungstanks (11), dem Extruder (13) der Guss- oder Spritzgussmaschine zugeleitet wird, worauf in min¬ destens einer Guss-Station oder Spritzguss-Station (14) Kunststoffteile geformt werden.A process according to claim 1, characterized in that ethylene in the reactor (6) is converted into powdery PE polyethylene, e.g. with the interposition of a separation tank (11), the extruder (13) of the casting or injection molding machine is fed, whereupon in at least one casting station or injection molding station (14) plastic parts are formed.
3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass aus einem Flüssiggastank (1) Ethylen einem Entspannungstank (3) zuge¬ führt, wonach das entspannte, gasförmige Ethylen dem Reaktor (6) zu¬ geleitet wird.3. The method according to claim 1 or 2, characterized in that from a liquefied gas tank (1) ethylene an expansion tank (3) zuge¬ leads, after which the expanded, gaseous ethylene to the reactor (6) zu¬ is passed.
4. Verfahren nach einem der Ansprüche 1 - 3, dadurch gekennzeichnet, dass vor dem Ausformen der Kunststoffteile dem Werkstoff Zusätze wie z.B. Treibmittel, Farbstoff, UV-Schutz und Flammschutz beigege¬ ben werden, z.B. im Extruder (13).4. The method according to any one of claims 1-3, characterized in that prior to the molding of the plastic parts the material additions such. Propellant, dye, UV protection and flame retardant, e.g. in the extruder (13).
5. Verfahren nach einem der Ansprüche 1 - 4, dadurch gekennzeichnet, dass das thermoplastische Pulver, z.B. das Polyethylenpulver, über eine Pulverfördereinrichtung, z.B. einem Transportband, dem Extruder (13) zugeführt wird. 5. The method according to any one of claims 1-4, characterized in that the thermoplastic powder, for example the polyethylene powder, via a powder conveying device, for example a conveyor belt, the extruder (13) is supplied.
6. Guss- oder Spritzgussaniage zur Ausführung des Verfahrens nach Anspruch 1 , dadurch gekennzeichnet, dass sie einen Reaktor (6) zur Bildung eines thermoplastischen Pulvers als Werkstoff, einen Extruder (13) und mindestens eine Guss-Station oder Spritzguss-Station (14) zur Formung von Kunststoffteilen aufweist.6. casting or Spritzgussaniage for carrying out the method according to claim 1, characterized in that it comprises a reactor (6) for forming a thermoplastic powder as a material, an extruder (13) and at least one casting station or injection molding station (14) having for molding plastic parts.
7. Guss- oder Spritzgussanlage nach Anspruch 6, dadurch gekennzeich¬ net, dass zwischen dem Reaktor (6) und dem Extruder (13) ein Tren¬ nungstank (11) angeordnet ist, in dem das thermoplastische Pulver, z.B. das Polyethylenpulver, von noch vorhandenem Gas trennbar ist.7. casting or injection molding plant according to claim 6, characterized gekennzeich¬ net, that between the reactor (6) and the extruder (13) a separation tank (11) is arranged, in which the thermoplastic powder, e.g. the polyethylene powder is separable from still existing gas.
8. Guss- oder Spritzgussanlage nach Anspruch 6 oder 7, gekennzeichnet durch eine Pulverfördereinrichtung, z.B. einem Transportband, durch die das thermoplastische Pulver, z.B. das Polyethylenpulver, dem Ex¬ truder (13) zuführbar ist.Casting or injection molding plant according to claim 6 or 7, characterized by a powder conveying device, e.g. a conveyor belt through which the thermoplastic powder, e.g. the polyethylene powder to which extruder (13) can be fed.
9. Guss- oder Spritzgussanlage nach einem der Ansprüche 6 - 8, gekenn¬ zeichnet durch einen Entspannungstank (3), in dem von einem Flüssig¬ gastank (1) zuführbares Flüssiggas, z.B. Ethylen, entspannbar und danach gasförmig dem Reaktor (6) zuleitbar ist.9. casting or injection molding plant according to any one of claims 6-8, gekenn¬ characterized by an expansion tank (3), in which by a Flüssig¬ gastank (1) feedable liquefied gas, e.g. Ethylene, relaxable and then gaseous to the reactor (6) can be fed.
10. Guss- oder Spritzgussanlage nach einem der Ansprüche 6 - 9, da¬ durch gekennzeichnet, dass der Reaktor (6) gezielt zur Verarbeitung eines für die herzustellenden Kunststoffteile spezieil gewünschten Werkstoffs ausgelegt ist, insbesondere hinsichtlich dessen Dichte und Mischung. 10. casting or injection molding plant according to one of claims 6 - 9, da¬ characterized in that the reactor (6) is designed specifically for processing a spezieil desired for the plastic parts to be produced material, in particular in terms of its density and mixture.
PCT/CH2004/000680 2004-07-01 2004-11-10 Method for producing plastic parts, and casting or injection molding system for carrying out said method WO2006002554A1 (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5928596A (en) * 1995-07-05 1999-07-27 Eastman Chemical Company Apparatus and process for distributing molten thermoplastic polymers from melt polymerization to molding machines
US5980797A (en) * 1997-03-20 1999-11-09 Eastman Chemical Company Apparatus and method for molding polyester articles having low acetaldehyde content directly from the melt formation using flash tank devoltatilization

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5928596A (en) * 1995-07-05 1999-07-27 Eastman Chemical Company Apparatus and process for distributing molten thermoplastic polymers from melt polymerization to molding machines
US5980797A (en) * 1997-03-20 1999-11-09 Eastman Chemical Company Apparatus and method for molding polyester articles having low acetaldehyde content directly from the melt formation using flash tank devoltatilization

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