Patent Application
20070261777
The invention relates to a method for coating grey goods for carpeting that has an upper layer with filaments. The invention also relates to a carpet itself that has an upper layer with filaments, and a coating device for coating grey goods for carpeting.
Carpets and methods for producing them are sufficiently well known. Carpets usually have an upper layer, which may be variously constructed. The upper layer may comprise pressed filaments, which are also referred to as mat or felt. The filaments are entangled with each other. Carpets of this sort are known as felts. In other carpet types the upper layer comprises yarns that are drawn through a layer of supporting material. The yarns are bundles of filaments. The yarns can be drawn through the supporting material as closed loops in a tufting process. The tufting process produces carpets known as tufted carpets. The loops can also be cut open, however, and the cut loops then form velour. Felts that have undergone further processing are also sometimes referred to as velours.
Regardless of the type of carpet, the upper layers are subjected to highdemands from abrasion and foot traffic; good filament binding prevents the filaments from being loosened by the later demands. There are various standardized testing procedures, such as the Lisson test, for measuring the traffic wear resistance of a carpet.
In the known carpets the filaments are fixed with latex. The use of latex has proven to be disadvantageous, however. Latex does not meet the requirements for recyclability. Procedures for applying latex are energy-intensive, and the production lines that use them require a lot of space. Attempts to employ other forms of binding, for example using thermoplastic materials, have failed so far because of the quality of the filament binding. The binding did not meet the requirements of standardized walking, tensile and abrasion demands.
It is therefore the object of the present invention, according to a first aspect, to make available a method for coating grey goods for carpeting in which binding the filaments with latex can be dispensed with, but which nevertheless provides a wear-resistant carpet.
According to a second aspect of the invention, the object of the invention is to provide a durable carpet without latex binding of the filaments.
According to a third aspect of the invention, the object of the invention is to provide a coating device for coating grey goods for carpeting which makes it possible to produce wear-resistant carpets without latex binding of the filaments.
The first aspect of the problem is solved by a method for coating a carpet according to claim 1, wherein a thermoplastic material is applied to the upper layer on the underside of the carpet and the filaments are bonded.
The method according to the invention makes it possible to bind the filaments of the upper layer of grey goods for carpeting firmly into the carpet. It has been found that adequate binding of the filaments can be accomplished by applying a thermoplastic material. Here a thermoplastic material is applied to the underside of the upper layer. The thermoplastic material then bonds the filaments in the grey goods. Compared to latex, thermoplastic materials and hence the entire carpet are more easily recyclable. Preferably, a particular form of slotted nozzle which will be described later is chosen for applying the thermoplastic material. The term thermoplastic is used here in general to mean an adhesive based on thermoplastic material or a formulation based on thermoplastic material.
Binding of the filaments with thermoplastic material is usable with various types of carpeting, in particular with tufted carpets, which may be of looped or velour type, but also with felts, which may likewise be of looped or velour type or in the form of fleece or needle felt.
Tufted carpets have yarns or filament bundles which are passed through a supporting material, so that segments of filament bundles protrude from the top and bottom sides of the supporting material. Preferably, the segments of filament bundles are passed through the supporting material on the underside of the carpet in the form of loops. Carpet loops are formed by a filament bundle on the top side of the carpet being passed through the supporting material to the underside of the carpet, being reversed through a loop, and being passed again from the underside of the carpet at a (penetration) point some distance away through the supporting material to the top of the carpet. The segments of filament bundles on the underside of the carpet are not fixed, and are therefore very sensitive, in part because they are drawn only loosely through the supporting material and in part because individual filaments can easily be pulled out of them.
Applying the thermoplastic material to the underside of the carpet glues the entire filament bundle permanently to the supporting material, since the thermoplastic material penetrates into interstices and thus actually makes the carpet durable. In addition, the thermoplastic material also penetrates at least part way into the filament bundle, so that the filaments become bonded together. If the thermoplastic material penetrates into the area of the outer periphery of the filament bundles, they have as it were a bonded protective sleeve due to the adhesive that has penetrated into them, which makes the carpet even more durable. The segments of filament bundles covered with thermoplastic material form so-called nubs on the underside of the carpet.
While the filament bundles in tufted carpets form loops on the underside of the carpet, their top sides can take various forms; for example, they can also have cut loops. But all types of tufted carpets are suitable for the coating according to the invention.
In a different version of a carpet, which is also known as felt, filaments are joined together to form the top layer by mechanical processes such as pressing, needle-punching or fulling, or by thermal processes. The filaments form a felt or mat. Felts have an unorganized structure on the underside of the carpet. The thermoplastic material is applied to the pressed upper layer on the underside of the carpet to fix the filaments. Because surprisingly it has turned out even with felts that filament binding can be accomplished in a simple way by applying thermoplastic material. Alternatively, a supporting layer can be positioned between the pressed filaments and the thermoplastic layer, even with felts.
Preferably, the upper layer is heated on the underside of the carpet, and a thermoplastic material is applied to the heated upper layer on the underside of the carpet. Heating the grey goods before applying the thermoplastic material, known as preheating, is preferably performed when hot melt adhesives are used. Hot melt adhesives are solid at ambient temperatures and fluid at elevated temperatures. The hot melt adhesive cools down more slowly when the grey goods are preheated, and is therefore able to penetrate into the segments of filament bundles for a longer time and to bond filaments together not only on the outer circumference but also in the interior of the filament bundles. In the case of felts the thermoplastic material is able to penetrate more deeply into the mat or felt.
In an especially preferred embodiment of the invention, the thermoplastic material is heated after it is applied to the underside of the upper layer. Such afterheating can be combined with the preheating. Being heated up twice enables the thermoplastic material, in particular hot melt adhesive, to penetrate especially deeply into the filament bundle or the mat. There can also be a controller that controls the intensity of the preheating and afterheating, and hence the depth of penetration of the thermoplastic material into the filaments. Preferably, infrared light (IR light) is used to heat the carpet. Using IR light in combination with an adhesive that reacts to it thermally makes it possible to dispense with complicated heating systems like those needed when latex is used to bind the filaments.
Preferably, the thermoplastic material is applied to the upper layer on the underside of the carpet in a contact process. A slotted nozzle or broad slotted nozzle can be used for that purpose. It is advantageous for the carpet to be transported past under an entry edge of an outflow slot of the slotted nozzle. While this is occurring, filaments bend down contrary to the transport direction. After passing the entry edge, they can stand upright again along the width of a pocket-like enlargement of an outflow slot of the slotted nozzle to receive the thermoplastic material. The pocket on the outflow slot enables a longer contact between the grey goods and the still-flowing adhesive which is being applied, and hence better binding of the filaments.
In a preferred refinement, a backing is laminated onto the underside of the applied thermoplastic material. The backing can be a fleece or netting material. To laminate the backing, all that is needed is to apply a sufficiently thick coating of thermoplastic material onto the underside of the upper layer, and then to immediately laminate the backing. The thermoplastic material bonds the backing to the underside. It is therefore not necessary to apply an additional coating (second application) for the backing. Hence an additional production step can be saved. A corresponding additional coating device can be dispensed with.
The second aspect of the problem is solved by a carpet having the features of claim 12, which has an upper layer with filaments, and a thermoplastic material applied to the upper layer on the underside of the carpet, which bonds the filaments in the carpet.
The carpet according to the invention is producible by at least one of the processes named above. The thermoplastic material that penetrates into the nubs and/or filaments of the upper layer on the underside of the carpet gives the carpet adequate strength and durability to satisfy standardized demand tests.
Both felts and tufted carpets can have a supporting material, onto or into which filaments are introduced. In this version the thermoplastic material bonds the filaments additionally with the supporting material.
Various choices are possible for the structure and type of the supporting material. The supporting material may have a web structure consisting of a plurality of synthetic threads oriented in two different directions, where synthetic threads of the one direction are passed alternately over and under the synthetic threads of the other direction and hence are woven together. The synthetic threads may also be yarns. The pattern of the weave has holes. In this preferred version of the carpet, the bundles of filaments are passed through the holes in the pattern of the weave. That enables cost-effective and simple introduction of the filaments into the carpet, which are preferably bonded onto the structure of the weave by means of hot melt adhesive. The supporting material may be a supporting fleece, for example a spundbond fleece. The supporting materials can vary greatly.
The third aspect of the problem is solved by a coating device according to the invention, for coating carpets having an upper layer, where the coating device has transport elements to transport the carpet along the transport device and a thermoplastic applicator to apply a thermoplastic material to the underside of the upper layer of the carpet being transported past the thermoplastic applicator.
The coating device can be used to employ at least one of the methods described above and for coating at least one of the types of grey goods described above. The coated grey goods preferably have a width of from less than one meter to several meters, and any length desired. The coating device is especially well suited for coating long runs of carpeting, which are sold as rolled goods.
In the coating device according to the invention, a thermoplastic applicator is preferably positioned so that the thermoplastic material flows out beneath the thermoplastic applicator, preferably from a slotted nozzle, and is applied to the carpet which is positioned beneath the thermoplastic applicator. In this version no additional means are needed to transfer the adhesive from the slotted nozzle to the carpet. The carpet transported beneath the thermoplastic applicator is transportable and supportable by a coating roller.
Preferably an adhesive, in particular hot melt adhesive, is applied to the carpet. In a preferred version of the coating device, a first heating element is located before the thermoplastic applicator, and/or a second heating element in the transport direction after the thermoplastic applicator. The two heating elements, which are preferably IR radiators, are used, as described above, to preheat and post-heat the carpet being fed through beneath the adhesive applicator, in order to improve and support penetration of the hot melt adhesive into the underside of the upper layer.
It has been found especially advantageous for the thermoplastic applicator to have a slotted nozzle for applying the thermoplastic material, in particular adhesive, preferably hot melt adhesive. The slotted nozzle can have an outflow slot for the thermoplastic material, and before the outflow slot in the direction of transport a sloping entry edge and behind the outflow slot at least one pocket. The sloping of the entry edge toward the carpet in the direction of transport enables uniform transporting of the carpet under the slotted nozzle, without the carpet getting caught. The pocket located after the outflow aperture collects thermoplastic material, and also serves to form a longer contact surface between the thermoplastic material and the carpet being transported past. The pocket enables the nubs and filaments to stand up and relax, or to open up again after passing the entry edge. This special form of the slotted nozzle achieves especially firm binding of the filaments.
The invention will be described on the basis of exemplary embodiments. The figures show the following:
The carpet 1 according to the invention which is shown in
On the underside of the carpet a hot melt adhesive 8 is applied to the filament bundle segments 3 that protrude from the underside of the carpet and to the underside of the supporting material 2. The hot melt adhesive 8 partially or completely penetrates the filament bundle segments 3 on the underside of the carpet, and forms nubs. On the one hand, the hot melt adhesive 8 bonds the filament bundle segment 3 firmly to the supporting material 2, and on the other hand it firmly attaches the filament bundle segments 3 on the underside of the carpet together. Because the hot melt adhesive 8 penetrates into the filament bundle segments 3 on the underside of the carpet, it bonds the individual filaments on the outer periphery of the filament bundle 7 together there, and thereby prevents individual filaments from being able to be pulled out of the filament bundle segments 3 on the underside of the carpet.
The supporting material 2 has a woven or braided structure (not drawn). In two directions that are perpendicular to each other, synthetic yarns are positioned parallel to each other in each of the two directions. The synthetic yarns of the one direction are alternately passed over and under the synthetic yarns of the other direction. After the binding of the nubs and filaments, a backing can be laminated onto the layer of adhesive on the underside of the carpet.
The filament bundles 7 are passed approximately vertically through the supporting material 2 at penetration points 9. At the same time, the penetration points 8 are made by the holes formed in the braided structure, and the filament bundles 7 are passed through these holes. The carpet loops 3 on the underside of the carpet form a space between themselves and the supporting material 2, which is completely filled with hot melt adhesive 8.
Positioned before and after the adhesive applicator 10 in the transport direction of the carpet 1 are a first infrared radiator 13 and a second infrared radiator 14, respectively. The purpose of the first infrared radiator 13 is to preheat the underside of the carpet. The purpose of the second infrared radiator 14, positioned after the adhesive applicator 10, is to post-heat the carpet 1. Preheating and post-heating the carpet enables the hot melt adhesive to remain in the fluid state for a longer time, and thus to penetrate deeper into the filament bundles and/or the structure of the weave. The depth of penetration can be controlled or influenced on the basis of the intensity of the post-heating and preheating.
Located before and after the support roller 12 in the transport direction of the carpet 1 are additional first 15 and second 16 deflecting rollers, which support the carpet 1 and bring it into the desired position.
The felt carpet shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 103 41 399.5 | Sep 2003 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP04/09925 | 9/6/2004 | WO | 6/27/2007 |
