EP0132563B1 - Use of uniaxially stretched strips of polypropylene or propylene-ethylene copolymers to make woven or knitted fabrics - Google Patents
Use of uniaxially stretched strips of polypropylene or propylene-ethylene copolymers to make woven or knitted fabrics Download PDFInfo
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- EP0132563B1 EP0132563B1 EP84106599A EP84106599A EP0132563B1 EP 0132563 B1 EP0132563 B1 EP 0132563B1 EP 84106599 A EP84106599 A EP 84106599A EP 84106599 A EP84106599 A EP 84106599A EP 0132563 B1 EP0132563 B1 EP 0132563B1
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- Prior art keywords
- tapes
- polypropylene
- layer
- ethylene
- knitted fabrics
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F8/00—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof
- D01F8/04—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers
- D01F8/06—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers with at least one polyolefin as constituent
Definitions
- the present invention relates to the use of monoaxially stretched ribbons made of polypropylene or propylene-ethylene copolymers, which have a significantly lower tendency to splice than the previously known ribbons, for the production of flexible fabrics or knitted fabrics in which the ribbons are movable with one another.
- Flexible woven or knitted fabrics made of monoaxially stretched tapes made of thermoplastic materials are being used increasingly in various fields of application, such as, for. B. Production of weaving, fabrics and use as geotextile and much more.
- Loose ribbon fabrics or knitted fabrics can serve, for example, as so-called Raschel fabrics for the storage of perishable piece goods, in particular fruits and vegetables.
- ribbons made of polypropylene are particularly suitable because of their good concealability and the high strength that can be achieved for them, but the disadvantage is the particularly pronounced tendency to splice of polypropylene structures which are stretched monoaxially because they are used to unravel the ribbon and to disrupt processing machines, e.g. . B. the looms leads, which occurs particularly disturbing where the ribbons are twisted during the weaving process, since there is a particularly high risk of splice.
- a multilayer and stretched packaging film which consists of a polypropylene layer which is covered by a polyethylene or ethylene-vinyl acetate copolymer layer.
- this film should only have a satisfactory transverse strength if the volume fraction of the polypropylene layer is not more than 20%.
- biaxially stretched polypropylene films are known which are coated on at least one side with a film-forming polymer containing at least 65% by weight of ethylene (AT-A-264144).
- EP-B-2606 describes weldable, biaxially stretched polypropylene films which are provided with an LLDPE layer (linear low density polyethylene) which makes up 2-10% of the total thickness of the film. It has also been proposed to obtain a rough surface film by coextruding, laminating and stretching two films, adding less of that of the two layers forming the surface layer and tearing when the laminated film is stretched (AT -A-368439) ..
- an air-permeable composite material has been proposed by using monoaxially stretched tapes made of a first plastic, for example made of HDPE (high density polyethylene) or polypropylene, on one or both sides with a second plastic with a lower melting temperature are coated in a fabric or fleece-like manner in at least two layers running at an angle to one another in such a way that the low-melting cover layers come to lie on one another, whereupon these layers are welded to one another by the action of heat and pressure.
- the base layer can include made of polypropylene, the top layer made of LDPE (low density polyethylene).
- DE-A-1704429 also describes the production of welded ribbon fabrics from multilayer film tapes, in which the outer layers, which have a lower melting point, are welded, while the core layer, e.g. is made of polyester or polyamide, remains unaffected.
- US-A-3187982 discloses band-like films or tubes made of monoaxially oriented, crystalline polyolefins, one surface of which is covered by a layer of a thermoplastic material which has a substantially lower melting point. These films are particularly suitable as tear tapes for packs made of thermoplastic materials. These tapes, which have been stretched at least 1: 7, are produced by coextrusion using the blown film process, the orientable layer usually representing the inner layer and subsequent stretching at a temperature at which the crystalline plastic is in the stretching region, but the plastic in the coating is in the molten state.
- This tape material is specifically described as high-density polyethylene as an orientable plastic and low-density polyethylene as a coating polymer, with a tape material after stretching rial arises in which both layers each have a thickness of 190 [tm.
- FR-A 2204726 describes a rigid fabric in which warp and weft threads consist of tapes which are produced from a film consisting of layers of low-density polyethylene (LDPE) and polyolefins, in particular high-density polyethylene or polypropylene, where the layer of low density polyethylene is on one of the surfaces.
- LDPE low-density polyethylene
- polyolefins in particular high-density polyethylene or polypropylene
- a likewise rigid fabric made of thermoplastic materials is described in DE-A-2127167.
- the strips woven into it have a surface layer made of thermoplastic material, the melting temperature of which is lower than that of the base plastic.
- the present invention accordingly relates to the use of monoaxially stretched tapes made of polypropylene or propylene-ethylene copolymers with an ethylene content of at most 30% by weight, which on the surface is composed of low-density polyethylene, which is up to 10% by weight higher alpha-olefins may contain polymerized or are covered from a copolymer of ethylene with vinyl acetate, the ribbons on one side being covered with the polyethylene layer in a thickness such that the base layer of the propylene polymer in the ribbon makes up at least 70% by volume for the production of flexible, not splicing fabrics or knitted fabrics in which the ribbons are movable among themselves.
- Polypropylene is primarily used for those types that are usually used for the production of ribbons. Depending on the intended use, it contains smaller or higher amounts of the usual processing stabilizers, antioxidants such as sterically hindered phenols and possibly also UV stabilizers.
- the propylene polymer can furthermore contain a mineral filler, in particular one such as talc, which has already been proposed to reduce the tendency to splice, and / or one or more inorganic pigments.
- a propellant can be added to the propylene polymer during production, which causes the polypropylene base layer to expand when extruded.
- the polymer used for the coating is low-density polyethylene, for example one below 0.94 g / cm 3 (LDPE), as is obtained by the so-called high-pressure process.
- ethylene copolymers with small amounts of polymerized alpha-olefins, the so-called LLDPE can also be used.
- Ethylene-vinyl acetate copolymers are also suitable, expediently those with a vinyl acetate content of less than 20% by weight.
- the tapes used according to the invention are produced by coextrusion using the processes known per se, such as blown film processes or processes with a slot die, the use of a slot die being preferred. Both a chill-roll process and a process with direct water bath cooling can be used here.
- the film produced in this way is then cut into ribbons, and the ribbons are then stretched, for example using a hot air duct, degrees of stretching being possible from 4 to about 12 times.
- stretching in the short gap can also be used, but is not necessary in order to suppress the tendency to splice.
- the reverse procedure is also possible, namely stretching the film and then cutting into strips in the stretching direction.
- the measure of the low tendency to splice of the tapes used according to the invention is the determination of the tear propagation resistance, which is carried out in accordance with DIN 53859. With this determination, a tear strength of 30 to 60 cN / mm is determined for polypropylene, which is caused by modification of polypropylene can be increased to about 50 to 80 cN / mm by the additives mentioned according to the prior art.
- the tapes used according to the invention on the other hand, have a tear strength of about 250 cN / mm and also higher, which is more than 3 times the tapes that were previously considered to be low-splicing.
- a co-extruded two-layer film was produced via a two-layer blown film head, a polypropylene homopolymer with a melt index (230 / 2.16) of 2.5 g / 1 Omin for the base layer and a low-density polyethylene (LDPE) with a melt index for the cover layer (190 / 2.16) of 0.8 g / 10 min and a density (23 ° C.) of 0.923 g / cm 3 , which was equipped with a lubricant, was used.
- LDPE low-density polyethylene
- the extrudate was cooled using conventional air cooling.
- the primary film obtained had a thickness of 0.115 mm, the thickness of the polypropylene layer being 0.095 mm and that of the LDPE layer 0.02 mm.
- This primary film was cut into strips with a width of 8.8 mm and stretched in a stretching furnace heated by hot air at a temperature of 145 ° C. and a stretching ratio of 1: 8.2. Subsequent to the stretching process, these tapes were subjected to a heat treatment at 130 ° C., a shrinkage of about 5% being permitted.
- the tapes thus obtained then had a thickness of 0.047 mm, the polypropylene layer being 0.037 mm thick (78% by volume). The polyethylene layer was therefore 0.01 mm thick.
- the tapes coated according to the invention thus had about 4 times the tear strength than those which were coextruded only from polypropylene.
- Example 2 The same polypropylene as in Example 1 and a linear low density polyethylene (so-called LLDPE) with a melt index (190 / 2.16) of 1.0 g / 10 min and a density (23 ° C.) of 0.920 g / cm 3 were used As described in Example 1, a primary film with a thickness of 0.105 mm was produced, the polypropylene layer being 0.085 mm. After cutting and drawing under the same conditions as in Example 1, tapes 0.042 mm thick were obtained. The polypropylene layer was 0.032 mm thick, that is 76 vol.%, The LLDPE layer had a thickness of 0.01 mm.
- LLDPE linear low density polyethylene
Abstract
Description
Die vorliegende Erfindung betrifft die Verwendung monoaxial verstreckter Bändchen aus Polypropylen oder Propylen-Äthylen-Copolymeren, die eine wesentlich geringere Spleissneigung besitzen als die bisher bekannten Bändchen, zur Herstellung von flexiblen Geweben oder Gewirken, in denen die Bändchen untereinander beweglich sind.The present invention relates to the use of monoaxially stretched ribbons made of polypropylene or propylene-ethylene copolymers, which have a significantly lower tendency to splice than the previously known ribbons, for the production of flexible fabrics or knitted fabrics in which the ribbons are movable with one another.
Flexible Gewebe oder Gewirke aus monoaxial verstreckten Bändchen aus thermoplastischen Kunststoffen finden eine immer breitere Verwendung in verschiedenen Anwendungsgebieten, wie z. B. Herstellung von Websachen, Flächengebilden sowie Einsatz beispielsweise als Geotextil und vieles mehr. Lockere Bändchengewebe oder -gewirke können beispielsweise als sog. Raschelgewebe der Aufbewahrung von verderblichen Stückgütern, insbesondere Obst und Gemüse, dienen. Hierbei sind Bändchen aus Polypropylen wegen ihrer guten Versteckbarkeit und der dafür erzielbaren hohen Festigkeit besonders geeignet, als Nachteil gilt allerdings die besonders ausgeprägte Spleissneigung von Gebilden aus Polypropylen, die monoaxial verstreckt sind, weil sie zum Auffasern der Bändchen und zu Störungen in den Verarbeitungsmaschinen, z. B. den Webstühlen, führt, was besonders dort störend auftritt, wo die Bändchen während des Webvorganges verdreht werden, da dort die Spleissgefahr besonders gross ist.Flexible woven or knitted fabrics made of monoaxially stretched tapes made of thermoplastic materials are being used increasingly in various fields of application, such as, for. B. Production of weaving, fabrics and use as geotextile and much more. Loose ribbon fabrics or knitted fabrics can serve, for example, as so-called Raschel fabrics for the storage of perishable piece goods, in particular fruits and vegetables. Here, ribbons made of polypropylene are particularly suitable because of their good concealability and the high strength that can be achieved for them, but the disadvantage is the particularly pronounced tendency to splice of polypropylene structures which are stretched monoaxially because they are used to unravel the ribbon and to disrupt processing machines, e.g. . B. the looms leads, which occurs particularly disturbing where the ribbons are twisted during the weaving process, since there is a particularly high risk of splice.
Es sind daher schon zahlreiche Vorschläge gemacht worden, die Spleissneigung von monoaxial verstreckten, bandartigen Gebilden aus Polypropylen herabzusetzen, wobei ausser verfahrenstechnischen Massnahmen, wie Verstrecken im kurzen Spalt (AT-A-369440) vor allem verschiedene Zusätze vorgeschlagen wurden, die die Spleissneigung vermindern sollen.Numerous proposals have therefore already been made to reduce the tendency to splice of monoaxially stretched, band-like structures made of polypropylene, and in addition to procedural measures such as stretching in the short gap (AT-A-369440), various additives have been proposed which are intended to reduce the tendency to splice .
So wird gemäss DE-A-1813649 der Zusatz von Polyäthylen eines bestimmten Schmelzindexbereiches und einer Dichte von 0,916 bis 0,960g/ cm3, gemäss AT-A-292186 der Zusatz von Poiyisobutylen eines hohen Molekulargewichtes, gemäss AT-A-295024 der Zusatz beider dieser Kunststoffe, gemäss DE-A-1807957 der Zusatz von Polyäthylen niedriger Dichte und gemäss AT-A-264815 der Zusatz eines Copolymeren von Alkylenen mit Vinylacetat oder Niederalkylacrylat empfohlen.Thus, according to DE-A-1813649, the addition of polyethylene of a certain melt index range and a density of 0.916 to 0.960g / cm 3 , according to AT-A-292186 the addition of polyisobutylene of a high molecular weight, according to AT-A-295024 the addition of both these plastics, according to DE-A-1807957 the addition of low density polyethylene and according to AT-A-264815 the addition of a copolymer of alkylenes with vinyl acetate or lower alkyl acrylate is recommended.
Andere Vorschläge beschäftigen sich mit dem Zusatz von mineralischen Füllstoffen, wie Talkum (AT-A-340310) oder Blähmitteln (GB-A-1174772 und AT-A-369440) zur Herabsetzung der Spleissneigung.Other proposals deal with the addition of mineral fillers, such as talc (AT-A-340310) or blowing agents (GB-A-1174772 and AT-A-369440) to reduce the tendency to splice.
Andererseits ist es schon verschiedentlich, insbesondere im Verpackungssektor, vorgeschlagen worden, zusammengesetzte Folien aus verschiedenen Polyolefinen herzustellen, da sie sich von einheitlichen Polyolefinfolien durch verschiedene Eigenschaften, wie Griff, Knickfestigkeit usw. unterscheiden.On the other hand, it has been proposed various times, in particular in the packaging sector, to produce composite films from different polyolefins, since they differ from uniform polyolefin films by different properties, such as grip, kink resistance, etc.
So wird gemäss AT-A-266696 ein mehrschichtiger und verstreckter Verpackungsfilm beschrieben, der aus einer Polypropylenschicht besteht, die durch je eine Polyäthylen- oder Äthylen-Vinylacetat-Copolymerschicht abgedeckt ist. Dieser Film soll aber nur dann eine befriedigende Querfestigkeit besitzen, wenn der Volumsanteil der Polypropylenschicht nicht mehr als 20% beträgt. Ferner sind biaxial gereckte Polypropylenfolien bekannt, die auf wenigstens einer Seite mit einem filmbildenden, wenigstens 65 Gew.% Äthylen enthaltenden Polymer überzogen sind (AT-A-264144). Schliesslich beschreibt die EP-B-2606 verschweissbare, biaxial gereckte Polypropylenfolien, die mit einer LLDPE-Schicht (linear low density polyethylene) versehen sind, die 2-10% der Geamtdicke der Folie ausmacht. Es ist auch vorgeschlagen worden, einen Film mit rauher Oberfläche dadurch zu erhalten, dass zwei Folien koextrudiert, laminiert und gedehnt werden, wobei jene der beiden Schichten, die die Oberflächenschicht bildet, in geringerer Menge zugesetzt wird und beim Dehnen der laminierten Folie aufreisst (AT-A-368439)..According to AT-A-266696, a multilayer and stretched packaging film is described which consists of a polypropylene layer which is covered by a polyethylene or ethylene-vinyl acetate copolymer layer. However, this film should only have a satisfactory transverse strength if the volume fraction of the polypropylene layer is not more than 20%. Furthermore, biaxially stretched polypropylene films are known which are coated on at least one side with a film-forming polymer containing at least 65% by weight of ethylene (AT-A-264144). Finally, EP-B-2606 describes weldable, biaxially stretched polypropylene films which are provided with an LLDPE layer (linear low density polyethylene) which makes up 2-10% of the total thickness of the film. It has also been proposed to obtain a rough surface film by coextruding, laminating and stretching two films, adding less of that of the two layers forming the surface layer and tearing when the laminated film is stretched (AT -A-368439) ..
Gemäss DE-A-2246051 ist die Herstellung eines luftdurchlässigen Verbundwerkstoffes vorgeschlagen worden, indem man monoaxial gereckte Bänder aus einem ersten Kunststoff, zum Beispiel aus HDPE (high density polyethylene) oder Polypropylen, die mit einem zweiten Kunststoff mit einer niedrigeren Schmelztemperatur ein- oder beidseitig beschichtet sind, in wenigstens zwei im Winkel zueinander verlaufenden Lagen gewebe-oder vliesartig in der Weise ablegt, dass die niedrig schmelzenden Deckschichten aufeinander zu liegen kommen, worauf diese Lagen durch Einwirkung von Hitze und Druck untereinander verschweisst werden. Die Basisschicht kann dabei u.a. aus Polypropylen, die Deckschicht aus LDPE (low density polyethylene) sein. Auch in der DE-A-1704429 ist die Herstellung verschweisster Bändchengewebe aus Mehrschichtfolienbändchen beschrieben, bei denen die Aussenschichten, die einen niedrigeren Schmelzpunkt besitzen, verschweisst werden, während die Kernschicht, die z.B. aus Polyester oder Polyamid gebildet ist, unangegriffen bleibt.According to DE-A-2246051, the production of an air-permeable composite material has been proposed by using monoaxially stretched tapes made of a first plastic, for example made of HDPE (high density polyethylene) or polypropylene, on one or both sides with a second plastic with a lower melting temperature are coated in a fabric or fleece-like manner in at least two layers running at an angle to one another in such a way that the low-melting cover layers come to lie on one another, whereupon these layers are welded to one another by the action of heat and pressure. The base layer can include made of polypropylene, the top layer made of LDPE (low density polyethylene). DE-A-1704429 also describes the production of welded ribbon fabrics from multilayer film tapes, in which the outer layers, which have a lower melting point, are welded, while the core layer, e.g. is made of polyester or polyamide, remains unaffected.
Schliesslich sind aus der US-A-3187982 bandartige Filme oder Schläuche aus monoaxial orientierten, kristallinen Polyolefinen bekannt, deren eine Oberfläche durch eine Schicht aus einem thermoplastischen Material bedeckt ist, das einen wesentlich niedrigeren Schmelzpunkt besitzt. Diese Filme sind vor allem als Aufreissbändchen für Packungen aus thermoplastischen Kunststoffen geeignet. Die Herstellung dieser mindestens 1:7 verstreckten Bänder erfolgt duch Coextrusion nach dem Blasfolienverfahren, wobei die orientierbare Schicht meist die Innenschicht darstellt und anschliessende Verstreckung bei einer Temperatur, bei der sich der kristalline Kunststoff im Reckbereich, der Kunststoff des Überzuges jedoch im geschmolzenen Zustand befindet. Konkret beschrieben ist dieses Bandmaterial an Polyäthylen hoher Dichte als orientierbarer Kunststoff und Polyäthylen niedriger Dichte als Überzugspolymer, wobei nach der Verstreckung ein Bandmaterial entsteht, in dem beide Schichten je eine Dicke von 190[tm aufweisen.Finally, US-A-3187982 discloses band-like films or tubes made of monoaxially oriented, crystalline polyolefins, one surface of which is covered by a layer of a thermoplastic material which has a substantially lower melting point. These films are particularly suitable as tear tapes for packs made of thermoplastic materials. These tapes, which have been stretched at least 1: 7, are produced by coextrusion using the blown film process, the orientable layer usually representing the inner layer and subsequent stretching at a temperature at which the crystalline plastic is in the stretching region, but the plastic in the coating is in the molten state. This tape material is specifically described as high-density polyethylene as an orientable plastic and low-density polyethylene as a coating polymer, with a tape material after stretching rial arises in which both layers each have a thickness of 190 [tm.
Von diesen Bändern wird die hohe Längsfestigkeit, die geringe Dehnbarkeit sowie eine geringe Neigung zur Fibrillierung hervorgehoben. Polypropylen, das wesentlich mehr zum Spleissen neigt als Polyäthylen hoher Dichte, ist zwar ebenfalls als mögliches Material für die verstreckbare Schicht erwähnt, jedoch sind keinerlei konkrete Angaben über die Eigenschaften von daraus gefertigten Bändern angegeben, sodass auch über eine ev. Verhinderung der Spleissneigung keine Aussagen gemacht werden.The high longitudinal strength, the low stretchability and a low tendency to fibrillate are emphasized by these tapes. Polypropylene, which is much more prone to splicing than high-density polyethylene, is also mentioned as a possible material for the stretchable layer, but no concrete information is given about the properties of tapes made from it, so that no statements about a possible prevention of splicing are given be made.
Weiters wird in der FR-A 2204726 ein starres Gewebe beschrieben, bei dem Kett- und Schussfäden aus Bändern bestehen, die aus einer Folie bestehend aus Schichten von Polyethylen niedriger Dichte (LDPE) und Polyolefinen, insbesondere Polyethylen hoher Dichte oder Polypropylen hergestellt werden, wobei sich die Schicht aus Polyethylen niedriger Dichte auf einer der Oberflächen befindet. Um die Stabilität dieses Gewebes zu verbessern, wird dieses auf eine Temperatur zwischen dem Erweichungspunkt und dem Schmelzpunkt des LDPE erhitzt, wodurch eine Verbindung an jenen Kreuzungsstellen erreicht wird, an denen Schichten von LDPE miteinander in Kontakt sind.Furthermore, FR-A 2204726 describes a rigid fabric in which warp and weft threads consist of tapes which are produced from a film consisting of layers of low-density polyethylene (LDPE) and polyolefins, in particular high-density polyethylene or polypropylene, where the layer of low density polyethylene is on one of the surfaces. In order to improve the stability of this tissue, it is heated to a temperature between the softening point and the melting point of the LDPE, whereby a connection is achieved at those crossing points where layers of LDPE are in contact with one another.
Ein ebenfalls starres Gewebe aus thermoplastischen Kunststoffen ist in der DE-A-2127167 beschrieben. Die darin verwebten Streifen weisen eine Oberflächenschicht aus thermoplastischem Kunststoff auf, dessen Schmelztemperatur niedriger ist als die des Basiskunststoffes. Auf jene Seite des Gewebes, auf der die Oberflächenschicht aus niedrig schmelzendem Kunststoff an praktisch allen Stellen vorhanden ist, werden eine oder mehrere Überzugsschichten aus demselben thermoplastischen Kunststoff aufgebracht und so eine feste Verbindung der Gewebefäden erreicht.A likewise rigid fabric made of thermoplastic materials is described in DE-A-2127167. The strips woven into it have a surface layer made of thermoplastic material, the melting temperature of which is lower than that of the base plastic. On that side of the fabric on which the surface layer made of low-melting plastic is present at practically all locations, one or more coating layers made of the same thermoplastic material are applied, thus achieving a firm bond between the fabric threads.
Es konnte nun überraschenderweise gefunden werden, dass aus Polypropylen monoaxial verstreckte Bändchen mit geringer Spleissneigung erhalten werden, die sich hervorragend zur Herstellung von flexiblen Geweben und Gewirken, in denen die Bändchen untereinander beweglich sind, eignen, wenn ein dünner Polypropylenfilm mit einem noch wesentlich dünneren, durch Coextrusion erzeugten Film aus Polyäthylen niedriger Dichte oder Copolymeren desselben, überzogen wird, wobei unter diesen Bändchen in erster Linie solche mit einer Gesamtdicke von unter 150 jim zu verstehen sind. Wesentlich für eine eindwandfreie Haftung der beiden Schichten untereinander ist hierbei, dass der Polyäthylenfilm maximal 30% des Volumens des Polypropylenfilms ausmacht. Es war nicht vorhersehbar, dass derartig dünne Überszugsfilme die Spleissneigung von Polypropylen wirksam herabsetzen, zumal gemäss AT-A-266696 an Verpackungsfilmen bei höheren Polypropylenanteilen als 20 Vol.% eine geringere Querfestigkeit, bedingt durch die Spleissneigung des Polypropylens, festgestellt wurde.It has now surprisingly been found that monoaxially stretched tapes with a low tendency to splice are obtained from polypropylene, which are outstandingly suitable for the production of flexible fabrics and knitted fabrics in which the tapes are movable with one another if a thin polypropylene film with an even thinner, coextrusion-produced film of low-density polyethylene or copolymers thereof, these tapes primarily being understood to mean those with a total thickness of less than 150 μm. It is essential for perfect adhesion of the two layers to one another that the polyethylene film makes up a maximum of 30% of the volume of the polypropylene film. It was not foreseeable that such thin coating films would effectively reduce the tendency of polypropylene to splice, especially since, according to AT-A-266696, a lower transverse strength was found in packaging films with polypropylene contents higher than 20% by volume, due to the tendency of polypropylene to splice.
Gegenstand der vorliegenden Erfindung ist demnach die Verwendung von monoaxial verstreckten Bändchen aus Polypropylen oder Propylen-Äthylen-Copolymeren mit einem Äthylenanteil von maximal 30 Gew.%, die an der Oberfläche mit Polyäthylen niederer Dichte, das bis zu 10 Gew.% höhere alpha-Olefine einpolymerisiert enthalten kann oder aus einem Copolymeren des Äthylens mit Vinylacetat bedeckt sind, wobei die Bändchen an einer Seite mit der Polyäthylenschicht in einer Dicke bedeckt sind, dass die Basisschicht aus dem Propylenpolymeren im Bändchen mindestens 70 Vol.% ausmacht, zur Herstellung von flexiblen, nicht spleissenden Geweben oder Gewirken, in denen die Bändchen untereinander beweglich sind.The present invention accordingly relates to the use of monoaxially stretched tapes made of polypropylene or propylene-ethylene copolymers with an ethylene content of at most 30% by weight, which on the surface is composed of low-density polyethylene, which is up to 10% by weight higher alpha-olefins may contain polymerized or are covered from a copolymer of ethylene with vinyl acetate, the ribbons on one side being covered with the polyethylene layer in a thickness such that the base layer of the propylene polymer in the ribbon makes up at least 70% by volume for the production of flexible, not splicing fabrics or knitted fabrics in which the ribbons are movable among themselves.
Als Polypropylen dienen hierbei in erster Linie jene Typen, die üblicherweise für die Herstellung von Bändchen eingesetzt werden. Es enthält je nach Verwendungszweck geringere oder höhere Mengen an den üblichen Verarbeitungsstabilisatoren, Antioxydantien, wie sterisch gehinderte Phenole und evtl. auch an UV-Stabilisatoren.Polypropylene is primarily used for those types that are usually used for the production of ribbons. Depending on the intended use, it contains smaller or higher amounts of the usual processing stabilizers, antioxidants such as sterically hindered phenols and possibly also UV stabilizers.
Das Propylenpolymere kann ferner, wenn vom Effekt her erwünscht, einen mineralischen Füllstoff, insbesondere einen solchen wie Talkum, der bereits zur Herabsetzung der Spleissneigung vorgeschlagen wurde, und/oder ein oder mehrere anorganische Pigmente enthalten. Schliesslich kann dem Propylenpolymeren bei der Herstellung ein Treibmittel zugesetzt werden, das beim Extrudieren ein Aufblähen der Polypropylenbasisschicht bewirkt. Als Polymeres für den Überzug findet Polyäthylen niedriger Dichte, etwa einer solchen unter 0,94g/cm3 (LDPE), wie es mit dem sog. Hochdruckverfahren erhalten wird, Anwendung. Es können aber auch Äthylencopolymere mit geringen Mengen an einpolymerisierten alpha-Olefinen, das sog. LLDPE, zum Einsatz kommen. Ebenso geeignet sind Äthylen-VinylacetatCopolymere, zweckmässigerweise solche mit einem Vinylacetatgehalt unter 20 Gew.%.If desired, the propylene polymer can furthermore contain a mineral filler, in particular one such as talc, which has already been proposed to reduce the tendency to splice, and / or one or more inorganic pigments. Finally, a propellant can be added to the propylene polymer during production, which causes the polypropylene base layer to expand when extruded. The polymer used for the coating is low-density polyethylene, for example one below 0.94 g / cm 3 (LDPE), as is obtained by the so-called high-pressure process. However, ethylene copolymers with small amounts of polymerized alpha-olefins, the so-called LLDPE, can also be used. Ethylene-vinyl acetate copolymers are also suitable, expediently those with a vinyl acetate content of less than 20% by weight.
Die Herstellung der erfindungsgemäss verwendeten Bändchen erfolgt durch Coextrusion nach den an sich bekannten Verfahren, wie Blasfolienverfahren oder Verfahren mit Breitschlitzdüse, wobei die Anwendung einer Breitschlitzdüse bevorzugt ist. Hierbei kann sowohl ein Chill-Roll-Verfahren als auch ein Verfahren mit direkter Wasserbadkühlung dienen. Die so hergestellte Folie wird sodann in Bändchen geschnitten, und die Bändchen werden anschliessend beispielsweise unter Anwendung eines Heissluftkanals verstreckt, wobei Verstreckungsgrade vom 4- bis etwa 12fachen in Frage kommen. Es ist aber auch eine Verstreckung im Kurzspalt anwendbar, jedoch im Hinblick auf eine Unterdrückung der Spleissneigung nicht erforderlich. Prinzipiell ist auch die umgekehrte Vorgangsweise, nämlich Verstrecken der Folie und anschliessendes Schneiden in Bändchen in Reckrichtung möglich.The tapes used according to the invention are produced by coextrusion using the processes known per se, such as blown film processes or processes with a slot die, the use of a slot die being preferred. Both a chill-roll process and a process with direct water bath cooling can be used here. The film produced in this way is then cut into ribbons, and the ribbons are then stretched, for example using a hot air duct, degrees of stretching being possible from 4 to about 12 times. However, stretching in the short gap can also be used, but is not necessary in order to suppress the tendency to splice. In principle, the reverse procedure is also possible, namely stretching the film and then cutting into strips in the stretching direction.
Als Mass für die geringe Spleissneigung der erfindungsgemäss verwendeten Bändchen dient die Bestimmung der Weiterreissfestigkeit, die in Anlehnung an DIN 53859 durchgeführt wird. Bei dieser Bestimmung wird für Polypropylen eine Weiterreissfestigkeit von 30 bis 60 cN/mm ermittelt, die durch Modifizierung von Polypropylen durch die genannten Zusätze gemäss Stand der Technik auf etwa 50 bis 80 cN/mm gesteigert werden kann. Die erfindungsgemäss verwendeten Bändchen besitzen hingegen eine Weiterreissfestigkeit von etwa 250 cN/mm und auch höher, was mehr als das 3fache jener Bändchen ist, die bisher als spleissarm gegolten haben. Durch die Verminderung der Spleissneigung sind solche Bändchen für die Erzeugung von sog. Raschelgeweben oder Drehergeweben, bei denen die Bändchen im Zuge der Herstellung durch Verdrehen besonders beansprucht werden, geeignet. Diese eklatante Herabsetzung der Spleissneigung, gepaart mit einer Herstellung, die einfacher ist als die bisher übliche Herstellung aus modifizierten Polypropylenen, da damit die Bereistellung einer gesonderter Type bzw. gesonderter Typen entfällt, stellt eine bedeutende Bereicherung der Technik dar.The measure of the low tendency to splice of the tapes used according to the invention is the determination of the tear propagation resistance, which is carried out in accordance with DIN 53859. With this determination, a tear strength of 30 to 60 cN / mm is determined for polypropylene, which is caused by modification of polypropylene can be increased to about 50 to 80 cN / mm by the additives mentioned according to the prior art. The tapes used according to the invention, on the other hand, have a tear strength of about 250 cN / mm and also higher, which is more than 3 times the tapes that were previously considered to be low-splicing. By reducing the tendency to splice, such ribbons are suitable for the production of so-called Raschel fabrics or leno fabrics, in which the ribbons are particularly stressed by twisting during manufacture. This blatant reduction in the tendency to splice, paired with a production that is simpler than the previously customary production from modified polypropylenes, since the provision of a separate type or separate types is thus eliminated, represents a significant enrichment of the technology.
In den nachfolgenden Beispielen soll die Durchführung vorliegender Erfindung näher erläutert werden.The implementation of the present invention is to be explained in more detail in the examples below.
Im Strangpressverfahren wurden über einen Zweischichtblasfolienkopf eine coextrudierte Zweischichtfolie hergestellt, wobei für die Basisschicht ein Polypropylen Homopolymerisat mit einem Schmelzindex (230/2,16) von 2,5 g/1 Omin und für die Deckschicht ein Polyäthylen niederer Dichte (LDPE) mit einem Schmelzindex (190/2,16) von 0,8g/10min und einer Dichte (23°C) von 0, 923g/cm3, das mit einem Gleitmittel ausgerüstet war, diente.In the extrusion process, a co-extruded two-layer film was produced via a two-layer blown film head, a polypropylene homopolymer with a melt index (230 / 2.16) of 2.5 g / 1 Omin for the base layer and a low-density polyethylene (LDPE) with a melt index for the cover layer (190 / 2.16) of 0.8 g / 10 min and a density (23 ° C.) of 0.923 g / cm 3 , which was equipped with a lubricant, was used.
Die Kühlung des Extrudates erfolgte über eine übliche Luftkühlung. Die dabei erhaltene Primärfolie hatte eine Dicke von 0,115mm, wobei die Dicke der Polypropylenschicht 0,095 mm, jene der LDPE-Schicht 0,02 mm betrug. Diese Primärfolie wurde zu Bändern einer Breite von 8,8mm geschnitten und in einem mittels Heissluft beheizten Reckofen bei einer Temperatur von 145°C und einem Reckverhältnis von 1:8,2 verstreckt. Diese Bändchen wurden anschliessend an den Reckvorgang einer Thermofizierung bei 130°C unterzogen, wobei ein Schrumpf von etwa 5% zugelassen wurde.The extrudate was cooled using conventional air cooling. The primary film obtained had a thickness of 0.115 mm, the thickness of the polypropylene layer being 0.095 mm and that of the LDPE layer 0.02 mm. This primary film was cut into strips with a width of 8.8 mm and stretched in a stretching furnace heated by hot air at a temperature of 145 ° C. and a stretching ratio of 1: 8.2. Subsequent to the stretching process, these tapes were subjected to a heat treatment at 130 ° C., a shrinkage of about 5% being permitted.
Die dabei erhaltenen Bändchen wiesen dann eine Dicke von 0,047 mm auf, wobei die Polypropylenschicht 0,037 mm dick war (78 Vol.%). Die Polyäthylenschicht war also 0,01 mm dick.The tapes thus obtained then had a thickness of 0.047 mm, the polypropylene layer being 0.037 mm thick (78% by volume). The polyethylene layer was therefore 0.01 mm thick.
Diese Bändchen wiesen folgende Eigenschaften auf:
Wird im Gegensatz dazu eine aus zwei Schichten des gleichen Polypropylens bestehende Folie einer Dicke von 0,115 mm hergestellt und werden die aus dieser Folie hergestellten Bändchen bei 155°C in gleichem Ausmass wie oben gereckt und bei 145°C fixiert, besitzt sie folgende Eigenschaften:
Die erfindungsgemäss beschichteten Bändchen hatten also etwa die 4fache Weiterreissfestigkeit wie jene, die nur aus Polypropylen coextrudiert wurden.The tapes coated according to the invention thus had about 4 times the tear strength than those which were coextruded only from polypropylene.
Aus dem gleichen Polypropylen wie in Beispiel 1 und einem linearen Polyäthylen niederer Dichte (sog. LLDPE) mit einem Schmelzindex (190/2,16) von 1,0g/10min und einer Dichte (23°C) von 0,920 g/cm3 wurde, wie in Beispiel 1 beschrieben, eine Primärfolie einer Dicke von 0,105mm erzeugt, wobei die Polypropylenschicht 0,085mm ausmachte. Nach dem Schneiden und einer Rekkung unter den gleichen Bedingungen wie in Beispiel 1 wurden Bändchen einer Dicke von 0,042 mm erhalten. Die Polypropylenschicht war 0,032mm dick, das sind 76 Vol.%, die LLDPE-Schicht hatte eine Dicke von 0,01 mm.The same polypropylene as in Example 1 and a linear low density polyethylene (so-called LLDPE) with a melt index (190 / 2.16) of 1.0 g / 10 min and a density (23 ° C.) of 0.920 g / cm 3 were used As described in Example 1, a primary film with a thickness of 0.105 mm was produced, the polypropylene layer being 0.085 mm. After cutting and drawing under the same conditions as in Example 1, tapes 0.042 mm thick were obtained. The polypropylene layer was 0.032 mm thick, that is 76 vol.%, The LLDPE layer had a thickness of 0.01 mm.
Diese Bändchen zeigten folgende Werte:
Claims (6)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AT84106599T ATE27622T1 (en) | 1983-06-27 | 1984-06-08 | USE OF MONOAXIALLY STRETCHED TAPES MADE OF POLYPROPYLENE OR PROPYLENE-ETHYLENE COPOLYMERS FOR THE MANUFACTURE OF KNITTED OR KNITTED FABRICS. |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3323109 | 1983-06-27 | ||
| DE19833323109 DE3323109A1 (en) | 1983-06-27 | 1983-06-27 | MONOAXIAL STRETCHED TAPES MADE OF POLYPROPYLENE OR PROPYLENE-AETHYLENE COPOLYMERS |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0132563A1 EP0132563A1 (en) | 1985-02-13 |
| EP0132563B1 true EP0132563B1 (en) | 1987-06-03 |
Family
ID=6202504
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP84106599A Expired EP0132563B1 (en) | 1983-06-27 | 1984-06-08 | Use of uniaxially stretched strips of polypropylene or propylene-ethylene copolymers to make woven or knitted fabrics |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0132563B1 (en) |
| AT (1) | ATE27622T1 (en) |
| DE (2) | DE3323109A1 (en) |
| DK (1) | DK310584A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4814131A (en) * | 1987-07-02 | 1989-03-21 | Atlas Sheldon M | Process for producing a shaped article, such as fiber composed of a hydrophobic polymer and a hydrophilic polymer |
| DE19513808C2 (en) * | 1995-04-12 | 1998-05-28 | Natura Verpackungs Gmbh | Process for the production of woven or knitted webs for the production of biodegradable sacks, bags, nets or the like. |
Family Cites Families (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1174772A (en) * | 1966-06-10 | 1969-12-17 | P P Payne & Sons Ltd | Improvements in or relating to Tapes and Ribbons |
| US3505164A (en) * | 1967-06-23 | 1970-04-07 | Hercules Inc | Self-bulking conjugate filaments |
| DE1704429A1 (en) * | 1967-07-05 | 1972-02-17 | Lissmann Alkor Werk | Process for the production of a textile-reinforced material based on plastic |
| JPS5235776B1 (en) * | 1969-01-31 | 1977-09-10 | ||
| GB1348247A (en) * | 1970-06-02 | 1974-03-13 | Shell Int Research | Coated fabrics of thermoplastics materials |
| JPS4840870A (en) * | 1971-09-25 | 1973-06-15 | ||
| CA995100A (en) * | 1972-10-26 | 1976-08-17 | James R. Barton | Manufacture of stabilized woven structures |
| DE2314052B2 (en) * | 1973-03-21 | 1978-11-16 | Veba-Chemie Ag, 4660 Gelsenkirchen- Buer | Monoaxially stretched splice-free packaging tapes made from polyolefins |
| NZ185412A (en) * | 1976-10-20 | 1980-03-05 | Chisso Corp | Heat-adhesive compsite fibres based on propylene |
| GB1590838A (en) * | 1978-04-28 | 1981-06-10 | Courtaulds Ltd | Woven fabric |
| DE8025884U1 (en) * | 1980-09-27 | 1982-04-01 | Barmag Barmer Maschinenfabrik Ag, 5630 Remscheid | FABRIC, IN PARTICULAR CARPET BASE FABRIC |
| AT369440B (en) * | 1981-06-01 | 1982-12-27 | Chemiefaser Lenzing Ag | METHOD FOR THE PRODUCTION OF FILM STRIPS |
-
1983
- 1983-06-27 DE DE19833323109 patent/DE3323109A1/en not_active Withdrawn
-
1984
- 1984-06-08 DE DE8484106599T patent/DE3464068D1/en not_active Expired
- 1984-06-08 EP EP84106599A patent/EP0132563B1/en not_active Expired
- 1984-06-08 AT AT84106599T patent/ATE27622T1/en not_active IP Right Cessation
- 1984-06-26 DK DK310584A patent/DK310584A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| ATE27622T1 (en) | 1987-06-15 |
| DE3323109A1 (en) | 1985-01-03 |
| DE3464068D1 (en) | 1987-07-09 |
| DK310584A (en) | 1984-12-28 |
| EP0132563A1 (en) | 1985-02-13 |
| DK310584D0 (en) | 1984-06-26 |
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