CH694291A5 - Production of multi-layer polyethylene terephthalate film, for the packaging/foodstuff industries, takes a flow directly from polycondensation for the base and diverted flows to take additives for the covering layers - Google Patents
Production of multi-layer polyethylene terephthalate film, for the packaging/foodstuff industries, takes a flow directly from polycondensation for the base and diverted flows to take additives for the covering layers Download PDFInfo
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- CH694291A5 CH694291A5 CH01921/03A CH19212003A CH694291A5 CH 694291 A5 CH694291 A5 CH 694291A5 CH 01921/03 A CH01921/03 A CH 01921/03A CH 19212003 A CH19212003 A CH 19212003A CH 694291 A5 CH694291 A5 CH 694291A5
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/36—Layered products comprising a layer of synthetic resin comprising polyesters
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- 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
- B29C48/08—Flat, e.g. panels flexible, e.g. films
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- 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
- B29C48/16—Articles comprising two or more components, e.g. co-extruded layers
- B29C48/18—Articles comprising two or more components, e.g. co-extruded layers the components being layers
-
- 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
- B29C48/285—Feeding the extrusion material to the extruder
- B29C48/29—Feeding the extrusion material to the extruder in liquid form
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- 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
- B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
- B29C48/50—Details of extruders
- B29C48/695—Flow dividers, e.g. breaker plates
- B29C48/70—Flow dividers, e.g. breaker plates comprising means for dividing, distributing and recombining melt flows
- B29C48/705—Flow dividers, e.g. breaker plates comprising means for dividing, distributing and recombining melt flows in the die zone, e.g. to create flow homogeneity
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- 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
- B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
- B29C48/50—Details of extruders
- B29C48/74—Bypassing means, i.e. part of the molten material being diverted into downstream stages of the extruder
- B29C48/745—Bypassing means, i.e. part of the molten material being diverted into downstream stages of the extruder for plasticising or homogenising devices
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- 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
- B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
- B29C55/02—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets
- B29C55/023—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets using multilayered plates or sheets
-
- 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
- B29C48/16—Articles comprising two or more components, e.g. co-extruded layers
- B29C48/18—Articles comprising two or more components, e.g. co-extruded layers the components being layers
- B29C48/21—Articles comprising two or more components, e.g. co-extruded layers the components being layers the layers being joined at their surfaces
-
- 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
- B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
- B29C48/50—Details of extruders
- B29C48/695—Flow dividers, e.g. breaker plates
-
- 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
- B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
- B29C48/50—Details of extruders
- B29C48/74—Bypassing means, i.e. part of the molten material being diverted into downstream stages of the extruder
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- 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
- B29K2067/00—Use of polyesters or derivatives thereof, as moulding material
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- 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
- B29K2105/0005—Condition, form or state of moulded material or of the material to be shaped containing compounding ingredients
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- 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
- B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
- B29K2995/0037—Other properties
- B29K2995/005—Oriented
- B29K2995/0053—Oriented bi-axially
Abstract
To form a multi-layer film of polyethylene terephthalate (PET), the plastics is taken directly from the polycondensation stage (P) into the main flow without modification to be used as the base layer (B). A flow is diverted from the main flow, to be mixed with additives and passed to the film jet (3) as flanking flows (A) for the covering layers. A small amount of polyester can be added to the PET. The layered film is passed onwards (19) for further processing. The flows are set by a distributor (V). The flanking layers can incorporate the same or different additives.
Description
Die Erfindung betrifft ein Verfahren zum Herstellen von mehrschichtigen Folien aus Schmelzen, die überwiegend aus Polyethylenterephthalat (PET) bestehen.
Nach dem Stand der Technik sind Verfahren bekannt, bei denen im so genannten Extrusions- oder Koextrusionsverfahren in Ein- oder Mehrwellenextrudern Granulate aufgeschmolzen und zu Folien verarbeitet werden. Solche Extruder sind hoch entwickelte Maschinen, die in Anschaffung und Verwendung ausserordentlich kostenintensiv sind.
Neben Einschichtfolien gehören heute Folien mit 2 oder mehreren Schichten, zum Beispiel für die Verpackungs- oder Nahrungsmittelindustrie, zum wohl bekannten Stand der Technik. Dabei können für einzelne Schichten Polymere verwendet werden, welche für bestimmte Aufgabenstellungen mit besonderen Eigenschaften gezielt durch Modifizieren mit speziellen Zusätzen entwickelt wurden.
Mehrschichtfolien bestehen in der Regel aus einer Basisschicht B und einer oder mehreren Deckschichten A, C usw., die gleichartig oder unterschiedlich zusammengesetzt oder gestaltet sein können.
Für die unterschiedliche Zusammensetzung erfolgt die Zugabe der notwendigen Zusätze zu den Polymeren entweder schon bei der Polykondensation oder vorteilhafter separat im so genannten Masterbatchverfahren beim Aufschmelzen des Polymer-Granulats im Extruder. Beide Methoden haben erhebliche Nachteile und erfordern zusätzliche Anlagen zur Herstellung der besonderen Polymerzusammensetzungen.
Wie in der DE-OS 1 604 368 beschrieben, führt jedes Aufschmelzen, insbesondere von PET-Granulaten, wegen der Restfeuchtigkeit der Granulate und der thermischen Beanspruchung der Polymeren zu Abbau und damit über Viskositätsverlust zu Uneinheitlichkeiten in Polymeren, die die Verformbarkeit und die Qualität der Folien beeinflussen. Polyethylenterephthalat-Granulate für die Folienherstellung müssen deshalb ein aufwändiges mehrstufiges und kostenintensives Trocknungsverfahren durchlaufen.
Es bestand deshalb die Aufgabe, für die Herstellung von PET-Folien, insbesondere von Mehrschichtfolien, den Einsatz von Granulat als Verfahrensrohstoff zu vermeiden.
Diese Aufgabe wird durch das Verfahren zum Direktverformen von PET-Schmelze zu mehrschichtigen Folien gemäss Anspruch 1 gelöst.
Sie wird insbesondere gelöst durch ein Verfahren, in dem eine Schmelze, die überwiegend aus Poly-ethylenterephthalat besteht, aus der Polykondensation direkt der Verformung zu Folien zugeführt wird. Dazu wird für die so genannte Basisschicht B bevorzugt unveränderte PET-Schmelze verwendet. Für die Deckschichten kann die gleiche Schmelze vor der Verformung über geeignete Vorrichtungen im Seitenstrom kontinuierlich mit beliebigen Zusätzen versehen werden.
Dabei können selbstverständlich für gleiche oder unterschiedliche Produkte, also zum Beispiel auch für Mehrschichtfolien mit unterschiedlichem Aufbau, gleichzeitig verschiedene Seitenstrom-Vorrichtungen mit eigenen Verformungen eingesetzt werden. Andererseits kann eine Seitenstrom-Vorrichtung auch mehrere Verformungen gleichzeitig beliefern.
Bevorzugt betrifft das erfindungsgemässe Verfahren die Herstellung von mehrschichtigen Folien, welche aus einer Basisschicht B und mindestens einer Deckschicht A bestehen. Das Verhältnis der Massenanteile der Basis- und der Deckschichten liegt zwischen 90 zu 10 bis 60 zu 40 und für 3-Schicht-Folien bevorzugt zwischen 85 zu 15 bis 75 zu 25.
Die nach dem erfindungsgemässen Verfahren hergestellten mehrschichtigen, bevorzugt dreischichtigen Folien sind wahlweise symmetrisch oder asymmetrisch aufgebaut. Dabei können die einzelnen Schichten durch unterschiedliche Zusatzmischungen eine unterschiedliche Zusammensetzung aufweisen. Das Verfahren eignet sich zur Herstellung von Mehrschicht-Flach- oder -Blasfolien.
In einer bevorzugten Ausführung für 3-Schicht-Folien wird die Basisschicht B beidseits mit einer Deckschicht A zusammengeführt, wobei diese beiden Deckschichten besonders bevorzugt die gleiche Schmelzezusammensetzung haben.
Die im Verfahren verwendeten PET-Schmelzen bestehen für alle Schichten im Wesentlichen aus kristallisierbarem Polyethylenterephthalat, dem geringe Mengen eines weiteren Polyesters nach dem Stand der Technik, z.B. Polyethylennaphthenat, zugemischt sein können, sowie die ebenfalls aus den durch den Stand der Technik für die Veresterung oder Umsterung bekannten Katalysatoren.
Die Menge des weiteren Polyesters beträgt vorteilhaft 0,1 bis 5 Gew.-%. Die IV-Viskosität der Polyesterschmelze liegt vorteilhaft zwischen 0,59 und 0,68.
Die einzelnen Schichten, insbesondere die Deckschichten A, enthalten ausserdem Zusätze, zum Beispiel Additive, die die Folienherstellung begünstigen oder auf die Verwendung der Folien zugeschnitten sind oder Regranulat aus der Folienherstellung.
Als Additive werden beispielsweise Stabilisatoren, Pigmente, Füller, Flammfestzusätze und Leitfähigkeitsverstärker eingesetzt, wobei als Pigment SiO 2 bevorzugt wird.
In den Weiterverarbeitungsschritten werden die Folien bevorzugt durch biaxiale Verstreckung in bekannter Weise orientiert. Die bevorzugten 3-SchichtFolien weisen beispielsweise im verstreckten Zustand Dicken zwischen 0,5 mu m bis 25 mu m auf, wobei A bevorzugt zwischen 0,1 mu m und 5 mu m und B bevorzugt zwischen 0,3 mu m und 15 mu m dick ist.
Besonders bevorzugt sind 3-Schicht-Folien, bei denen die Dicke der Deckschichten A zwischen 1,0 und 1,5 mu m und die Dicke von B zwischen 10 und 15 mu m liegt.
Bevorzugt wird die Folie gemäss bekanntem Stand der Technik nach Verlassen der Foliendüse in einem elektrostatischen Feld an die Kühlwalze angelegt, nachfolgend der Längs- und Querstreckung bei Tg + 10 DEG C bis Tg + 60 DEG C und bei einem Gesam streckverhältnis von 4 bis 12 unterworfen und schliesslich vor dem Wickeln mit Geschwindigkeit beispielsweise zwischen 300 und 400 m/min bei 150 bis 250 DEG C thermofixiert.
Der Ablauf des Verfahrens für eine 3-Schicht-Folie ABA mit zwei gleichen Deckschichten mit Zugabe der Zusätze über einen Teilstrom des Schmelzeseitenstroms für A wird durch das Schema der Fig. 1 erläutert.
Fig. 2 zeigt eine Verfahrensvariante mit Zugabe der Zusätze als Masterbatch-Schmelze zum Schmelzeseitenstrom für A. Liste der Bezugszeichen:
P Polykondensation
V Verteileinheit
1 Fördereinheit
2 Fördereinheit
3 Foliendüse
4 Seitenstromabzweigung
5 Fördereinrichtung
6 Teilstromabnahme
7 Dosiereinheit
8 Dosiereinheit
9 Mischeinheit
10 Additivzugabe
11 Einmündung
12 Fördereinrichtung
13 Deckschicht-Verzweigung
14 Mischer
15 Abzweig vom Hauptstrom B
16 separate Verwendung der Schmelze
17 Abzweig für Schmelze A
18 Wiederzugabe von Schmelze A
19 Weiterverarbeitung
20 Fördereinheit
In Fig. 1 wird die PET-Schmelze aus der Polykondensation (P) von einer Fördereinrichtung (1) übernommen, die den Schmelzestrom für die Schicht B über eine weitere Fördereinrichtung (2) zur Foliendüse (3) fördert. Über eine Verteileinheit (V) ist die Belieferung mehrerer separater Linien zur Folienherstellung möglich.
Bei (4) wird ein Seitenstrom aus der Schmelze für die Deckschichten A abgezweigt und durch die Fördereinrichtungen (5) und (12) über die Verzweigung (13) für 2 Deckschichten A ebenfalls zur Foliendüse (3) gefördert.
Aus dem Seitenstrom wird bei (6) ein Teilstrom der Schmelze abgenommen, der durch die Dosiereinheiten (7) und (8) geführt wird und bei der Einmündung (11) wieder mit dem Seitenstrom für A vereinigt und im Mischer (14) intensiv vermischt wird, nachdem er in der Mischeinheit (9) mit dem mindesten einen Additiv (10) versetzt worden ist. Beim Abzweig (15) kann ein weiterer Teil der Schmelze aus dem Hauptstrom B zur separaten Verwendung abgezweigt und z.B. der Herstellung (16) von Chips zugeführt werden.
Vorteilhaft ist nach der Fördereinheit (20) über einen weiteren Abzweig (17) die Austragung von beispielsweise 10 bis 20% und über eine weitere Einmündung (18) die Wiederzugabe des additivhaltigen Seitenstroms A möglich, die insbesondere bei Durchsatzänderungen oder Störungen in der Folienherstellung bei (3) den Durchsatz in der Mischeinheit (9) konstant halten und so Verweilzeitänderungen im Schmelzestrom und thermischen Abbau des Polymers vermeiden lassen.
Nach dem Verlassen der Foliendüse (3) wird die Folie der Weiterverarbeitung (19), insbesondere der biaxialen Verstreckung, zugeführt.
In der Verfahrensvariante nach Fig. 2 wird die Masterbatch-Schmelze bei (18) über die Fördereinheit (20) und die Dosiereinheit (8) durch die Einmündung (11) der Seitenstromschmelze A zugeführt.
Das erfindungsgemässe Verfahren zeichnet sich durch einen besonders kurzen Weg von der Polykondensation zur Verformung und damit durch eine hohe Konstanz der Qualität der PET-Schmelze aus.
Von besonderem Vorteil ist der Wegfall der kostenintensiven Aufschmelz- und Extrusionseinheiten und des aufwändigen Trocknens des PET-Granulats nach der Herstellung und vor der Verarbeitung zu Folien.
Es ist somit erfindungswesentlich, dass die im Verfahren verwendete Schmelze für alle Schichten aus dem gleichen, direkt aus der Polykondensation entnommenen, aber gegebenenfalls verschieden modifizierten Polyethylenterephthalat oder Polyethylenter-ephthalatgemisch besteht. Verfahrenschritte, die über Granulat führen, sind ausdrücklich ausgeschlossen.
Die Erfindung beinhaltet ausserdem eine biaxial verstreckte Mehrschichtfolie, die durch das erfindungsgemässe Verfahren hergestellt wird.
The invention relates to a method for producing multilayer films from melts, which consist predominantly of polyethylene terephthalate (PET).
Methods are known from the prior art in which, in the so-called extrusion or coextrusion method, granules are melted in single or multi-screw extruders and processed into films. Such extruders are highly developed machines that are extremely expensive to buy and use.
In addition to single-layer films, films with two or more layers, for example for the packaging or food industry, are now well known in the art. Polymers can be used for individual layers, which have been developed for specific tasks with special properties by modification with special additives.
Multi-layer films generally consist of a base layer B and one or more cover layers A, C etc., which can be composed or designed in the same or different way.
For the different composition, the necessary additives are added to the polymers either already during the polycondensation or, advantageously, separately in the so-called masterbatch process when the polymer granules are melted in the extruder. Both methods have considerable disadvantages and require additional equipment for the production of the special polymer compositions.
As described in DE-OS 1 604 368, any melting, in particular of PET granules, leads to degradation due to the residual moisture of the granules and the thermal stress on the polymers, and thus to loss of viscosity, leading to inconsistencies in the polymers, which affect the deformability and the quality of the Affect slides. Polyethylene terephthalate granules for film production therefore have to go through a complex, multi-stage and cost-intensive drying process.
The object was therefore to avoid the use of granules as process raw material for the production of PET films, in particular multilayer films.
This object is achieved by the process for the direct shaping of PET melt into multilayer films according to claim 1.
It is solved in particular by a process in which a melt, which consists predominantly of polyethylene terephthalate, is fed directly from the polycondensation to the deformation into films. For this purpose, unchanged PET melt is preferably used for the so-called base layer B. For the cover layers, the same melt can be continuously provided with any additives in the side stream using suitable devices before the deformation.
Of course, different sidestream devices with their own deformations can be used simultaneously for the same or different products, for example also for multilayer films with different structures. On the other hand, a sidestream device can also supply several deformations at the same time.
The method according to the invention preferably relates to the production of multilayer films which consist of a base layer B and at least one cover layer A. The ratio of the mass fractions of the base and cover layers is between 90 to 10 to 60 to 40 and for 3-layer films preferably between 85 to 15 to 75 to 25.
The multilayer, preferably three-layer films produced by the process according to the invention are optionally constructed symmetrically or asymmetrically. The individual layers can have a different composition due to different additional mixtures. The process is suitable for the production of multilayer flat or blown films.
In a preferred embodiment for 3-layer films, the base layer B is brought together on both sides with a cover layer A, these two cover layers particularly preferably having the same melt composition.
The PET melts used in the process essentially consist of crystallizable polyethylene terephthalate, the small amounts of another polyester according to the prior art, e.g. Polyethylene naphthenate, can be admixed, and also from the catalysts known from the prior art for esterification or transesterification.
The amount of the further polyester is advantageously 0.1 to 5% by weight. The IV viscosity of the polyester melt is advantageously between 0.59 and 0.68.
The individual layers, in particular the cover layers A, also contain additives, for example additives which promote film production or are tailored to the use of the films, or regranulate from film production.
Stabilizers, pigments, fillers, flame retardants and conductivity enhancers are used as additives, with SiO 2 being preferred as the pigment.
In the further processing steps, the films are preferably oriented in a known manner by biaxial stretching. The preferred 3-layer films have, for example, thicknesses between 0.5 μm and 25 μm in the stretched state, A being preferably between 0.1 μm and 5 μm and B preferably between 0.3 μm and 15 μm is.
3-layer films are particularly preferred in which the thickness of the outer layers A is between 1.0 and 1.5 μm and the thickness of B is between 10 and 15 μm.
According to the known prior art, the film is preferably applied to the cooling roller in an electrostatic field after leaving the film nozzle, subsequently subjected to longitudinal and transverse stretching at Tg + 10 ° C. to Tg + 60 ° C. and at a total stretch ratio of 4 to 12 and finally heat-set, for example, between 300 and 400 m / min at 150 to 250 ° C. before winding.
The course of the process for a 3-layer film ABA with two identical cover layers with addition of the additives via a partial stream of the melt side stream for A is explained by the diagram of FIG. 1.
2 shows a process variant with addition of the additives as a masterbatch melt to the melt side stream for A. List of reference numerals:
P polycondensation
V distribution unit
1 conveyor unit
2 conveyor unit
3 foil nozzle
4 sidestream branch
5 conveyor
6 partial flow acceptance
7 dosing unit
8 dosing unit
9 mixing unit
10 Additive addition
11 confluence
12 conveyor
13 top layer branching
14 mixers
15 branch from main stream B
16 separate use of the melt
17 Branch for melt A
18 Addition of melt A
19 Further processing
20 conveyor unit
In Fig. 1, the PET melt from the polycondensation (P) is taken over by a conveyor (1) which conveys the melt flow for layer B via a further conveyor (2) to the film nozzle (3). A distribution unit (V) enables the delivery of several separate lines for film production.
At (4) a side stream is branched off from the melt for the cover layers A and also conveyed to the film nozzle (3) by the conveying devices (5) and (12) via the branching (13) for 2 cover layers A.
A partial stream of the melt is removed from the side stream at (6), which is passed through the metering units (7) and (8) and at the junction (11) is again combined with the side stream for A and is intensively mixed in the mixer (14) after it has been mixed with at least one additive (10) in the mixing unit (9). At branch (15) a further part of the melt can be branched off from main stream B for separate use and e.g. the manufacture (16) of chips are supplied.
After the conveyor unit (20), the discharge of, for example, 10 to 20% via a further branch (17) and, via a further junction (18), the additive-containing side stream A can be reproduced, which is particularly useful in the event of throughput changes or disruptions in film production ( 3) keep the throughput in the mixing unit (9) constant, thus avoiding changes in the residence time in the melt flow and thermal degradation of the polymer.
After leaving the film nozzle (3), the film is fed to further processing (19), in particular biaxial stretching.
In the process variant according to FIG. 2, the masterbatch melt is fed to the side stream melt A at (18) via the conveyor unit (20) and the metering unit (8) through the mouth (11).
The method according to the invention is characterized by a particularly short path from polycondensation to deformation and thus by a high level of consistency in the quality of the PET melt.
The elimination of the costly melting and extrusion units and the time-consuming drying of the PET granulate after production and before processing to films are particularly advantageous.
It is therefore essential to the invention that the melt used in the process for all layers consists of the same polyethylene terephthalate or polyethylene terephthalate mixture, which is taken directly from the polycondensation but may be modified differently. Process steps that lead over granulate are expressly excluded.
The invention also includes a biaxially stretched multilayer film which is produced by the method according to the invention.
Claims (11)
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CH01921/03A CH694291A5 (en) | 2003-11-07 | 2003-11-07 | Production of multi-layer polyethylene terephthalate film, for the packaging/foodstuff industries, takes a flow directly from polycondensation for the base and diverted flows to take additives for the covering layers |
CN2004100858803A CN1613635B (en) | 2003-11-07 | 2004-11-04 | Method for direct pouring polyethylene terephthalate smelt into film |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CH01921/03A CH694291A5 (en) | 2003-11-07 | 2003-11-07 | Production of multi-layer polyethylene terephthalate film, for the packaging/foodstuff industries, takes a flow directly from polycondensation for the base and diverted flows to take additives for the covering layers |
Publications (1)
Publication Number | Publication Date |
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CH694291A5 true CH694291A5 (en) | 2004-11-15 |
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CH01921/03A CH694291A5 (en) | 2003-11-07 | 2003-11-07 | Production of multi-layer polyethylene terephthalate film, for the packaging/foodstuff industries, takes a flow directly from polycondensation for the base and diverted flows to take additives for the covering layers |
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CN (1) | CN1613635B (en) |
CH (1) | CH694291A5 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102007016586A1 (en) | 2007-04-05 | 2008-10-09 | Zimmer Ag | Process for the direct and continuous production of low acetaldehyde polyester moldings |
WO2016100060A1 (en) * | 2014-12-18 | 2016-06-23 | Dow Global Technologies Llc | System and method for processing of low viscosity polymers |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN102367571B (en) * | 2011-09-20 | 2013-04-17 | 常州机电职业技术学院 | Preparation method for improving surface hydrophilicity of nanometer polyethylene terephthalate (PET) films |
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Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102007016586A1 (en) | 2007-04-05 | 2008-10-09 | Zimmer Ag | Process for the direct and continuous production of low acetaldehyde polyester moldings |
WO2008122414A1 (en) * | 2007-04-05 | 2008-10-16 | Lurgi Zimmer Gmbh | Method for the direct and continuous production of polyester mold bodies with low acetaldehyde content |
US8241546B2 (en) | 2007-04-05 | 2012-08-14 | Lurgi Zimmer Gmbh | Method for the direct and continuous manufacture of polyester moulded bodies with low acetaldehyde content |
DE102007016586B4 (en) | 2007-04-05 | 2018-10-04 | Lurgi Zimmer Gmbh | Process for the direct and continuous production of low acetaldehyde polyester moldings |
WO2016100060A1 (en) * | 2014-12-18 | 2016-06-23 | Dow Global Technologies Llc | System and method for processing of low viscosity polymers |
US11077585B2 (en) | 2014-12-18 | 2021-08-03 | Dow Global Technologies Llc | System for processing of low viscosity polymers |
Also Published As
Publication number | Publication date |
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CN1613635B (en) | 2011-03-02 |
CN1613635A (en) | 2005-05-11 |
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