AU2004270864A1

AU2004270864A1 - Method for coating grey goods for carpeting using a broad slotted nozzle

Info

Publication number: AU2004270864A1
Application number: AU2004270864A
Authority: AU
Inventors: Gerd Ostermann; Jurgen Steckelberg
Original assignee: Nordson Corp
Current assignee: Nordson Corp
Priority date: 2003-09-05
Filing date: 2004-09-06
Publication date: 2005-03-17
Also published as: US20070261777A1; WO2005024122A1; EP1660715A1; DE10341399A1; CN1846027A

Description

PUBLISHED SPECIFICATION VERIFICATION OF TRANSLATION (insert trar~slator's name) of ....... 7. ....................... ........ (translator's address) declare as follows: 1. That I am well acquainted with both the English and German languages, and 2. That the attached document is a true and correct translation made by me to the best of my knowledge and belief of: (a) The specification of International Bureau pamphlet numbered WO 2005/024122 International Application No. PCT/EP2004/009925 (Date) I (Signature of Translator) (No witness required) [R:\UBF)36425.doc:jyp 3remen: 3 September 2004 Our ref.: NA 2208-02WO MAN/WIG/bro Direct dial: 0421/36 35 46 Applicant/Owner NORDSON CORPORATION File No.: New application Nordson Corporation 28601 Clemens Road, Westlake, Ohio 44145-1119, USA Procedure for Coating a Carpet Article in the Grey State by Means of a Broad-Slot Nozzle The invention relates to a method of coating a carpet article in the grey state which has an upper layer with filaments. The invention also relates to a carpet itself having an upper layer with filaments, and to a coating apparatus for coating carpet articles in the grey state. Carpets and methods for their manufacture are sufficiently well known. Customarily, carpets possess an upper layer which can be formed in a variety of ways. The upper layer can be made from pressed filaments, which are also referred to as a laid assembly or a non-ordered assembly. In this case the filaments are interlocked with each other. Such carpets are known as felts. In other types of carpet, the upper layer consists of yams which are drawn through a layer of carrier material. The yams in question consist of bunches of filaments. The yarns may be drawn through the carrier material in the form of closed loops, using a tufting method. The type of carpet manufactured by the tufting method is known as tufted carpet. The loops may also, however, be cut and the cut loops then form velour. Sometimes, felts processed further are also known as velour. Regardless of the type of carpet, the upper layers are exposed to high abrasion and traffic loads. Good bonding of the filaments prevents the individual filaments from becoming detached when subsequently exposed to load stresses. There are various standardised test procedures, such as the Lisson test, to measure the ability of a carpet to withstand traffic loads. In the known types of carpet the filaments are held in place by latex. However, it has proved disadvantageous to use latex. Latex does not meet the specifications for recyclability. The methods used for applying latex consume large amounts of energy, and the associated manufacturing lines take up a lot of space. Attempts to adopt other methods of bonding, e.g. using thermoplastic materials, have so far failed due to the quality of the filament bonding. The bonding did not meet the requirements of the standardised traffic, tensile and abrasion load tests. It is therefore the task of the present invention, according to a first aspect, to provide a method for coating a carpet article, wherein latex bonding of the filaments can be dispensed with and nevertheless a durable carpet is produced. According to a second aspect of the invention, it is the task of the invention to make available a durable carpet without latex bonding of the filaments. According to a third aspect of the invention, it is the task of the invention to make available an apparatus for coating carpet articles in the grey state that makes it possible to produce durable carpets without using latex to bond the filaments. The first aspect of the task is solved by a method of coating a carpet according to Claim I in that a thermoplastic material is applied to the upper layer at the underside of the carpet, thereby bonding the filaments. The method according to the invention makes it possible to bond the filaments of the upper layer of a carpet article firmly in the carpet. It has been shown that adequate bonding of the filaments can be achieved by applying a thermoplastic material. A thermoplastic material is applied to the underside of the upper layer. The thermoplastic 2 material then bonds the filaments into the carpet article. Compared with latex, thermoplastic materials and thus also the entire carpet are easier to recycle. A specific type of slot nozzle, which is described further below, is preferably used to apply the thermoplastic material. By thermoplastic material is generally meant in this case a thermoplastic-based adhesive or a thermoplastic-based formulation. Using thermoplastic material to bond the filaments is a method that can be employed for various types of carpet, in particular for tufted carpets, which may be designed as looped or velour products, but it can also be employed in the case of felts, which may also take the form of looped or velour products or of non-woven or needle-felt material. Tufted carpets possess yarns or filament bunches which are passed through a carrier material so that portions of the filament bunches project above and below the carrier material. The filament bunch portions are preferably passed in the form of loops through the carrier material at the underside of the carpet. Carpet loops are formed by passing a filament bunch from the upper side of the carpet, through the carrier material, to the underside of the carpet; the filaments are then turned into a loop and passed upwards again from the underside of the carpet, through the carrier material, to the upper side of the carpet, at a different (penetration) point. The filament bunch portions are not anchored in place at the underside of the carpet and are therefore very fragile because, on the one hand, they are only loosely drawn through the carrier material and, on the other hand, individual filaments could easily be tom out of them. By applying the thermoplastic material to the underside of the carpet, on the one hand the entire filament bunch is firmly bonded to the carrier material, because the thermoplastic material penetrates into the interspaces and thus makes the carpet durable. On the other hand, the thermoplastic material also penetrates at least partially into the filament bunches so that the filaments become bonded to each other. If the thermoplastic material penetrates into the outer periphery of the filament bunches, then because of the adhesive's partially penetrating into them they possess, as it were, a bonded protective sheath that makes the carpet even more durable. The portions of the filament bunches that are coated with thermoplastic material thus form so-called naps at the underside of the carpet.. 3 While in the case of tufted carpets the bunches of filaments form loops at the underside of the carpet, they may be differently formed at the upper side; for example, they may also have cut loops. However, all types of tufted carpet are suitable for the coating according to the invention. In another embodiment of a carpet, which is also known as felt, the filaments are bonded with each other by mechanical methods such as pressing, needling or fulling, or by thermal methods to form the upper layer. The filaments form a non-orderly assembly or a laid assembly. At the underside of the carpet, felts exhibit a disordered structure. In order to bond the filaments, the thermoplastic material is applied to the compressed upper layer at the underside of the carpet. This is because, even in the case of felts, it has surprisingly been discovered that the application of thermoplastic material is a simple way to bond the filaments. Alternatively, also in the case of felts, a carrier layer may be arranged between the compressed filaments and the layer of thermoplastic material. The upper layer is preferably heated at the underside of the carpet and a thermoplastic material is applied at the underside of the carpet to the heated upper layer. The heating of the carpet article in the grey state prior to applying the thermoplastic material, i.e. the so called pre-heating process, is carried out preferably when using hot-melt adhesives. Hot melt adhesives are solid at ambient temperature and become liquid at elevated temperatures. In the case of pre-heated carpet articles in the grey state, the hot-melt adhesive cools more slowly and can therefore penetrate over a longer period of time into the filament bunch portions and can bond the filaments not just at their outer periphery but also inside the bunches of filaments. In the case of felts, the thermoplastic material can penetrate deeper into the laid or non-orderly assembly. In an especially preferred embodiment of the invention, the thermoplastic material is heated after being applied to the underside of the upper layer. Such subsequent heating can be combined with pre-heating. The double heating process permits the thermoplastic material, in particular hot-melt adhesive, to penetrate deep into the filament bunch or into 4 the laid assembly. Control means may also be provided to regulate the intensity of the pre-heating and the subsequent heating and thus to control the depth to which the thermoplastic material penetrates into the filaments. Preferably infra-red (IR) light is used to heat the carpet. The use of IR light combined with an adhesive that reacts thermally to such light makes it possible to dispense with complicated heating units, such as are required when latex is used to bond the filaments. The thermoplastic material is preferably applied by a contact method to the upper layer at the underside of the carpet. A slot nozzle or broad-slot nozzle may be used for this purpose. Advantageously, the carpet is transported along below an entry edge of a discharge slot in the slot nozzle. As this happens, the filaments are bent back against the direction of transport. Once they have passed the entry edge, they can stand up again along the width of a pocket-like widening of a discharge slot in the slot nozzle in order to accept the thermoplastic material. The pocket on the discharge slot permits longer contact between the carpet article in the grey state and the still fluid adhesive that is to be applied, thereby allowing better bonding of the filaments. In a preferred refinement a so-called backing is laminated at the underside of the carpet onto the thermoplastic material that has been applied. The backing may be either a non woven material or a net material. To laminate the backing onto the carpet it is sufficient to apply an adequately thick layer of thermoplastic material to the top layer, at the underside of the carpet, and directly thereafter to laminate on the backing. The thermoplastic material bonds the backing at the underside of the carpet. Thus, it is not necessary to apply a further coating (second application) for the backing. In this manner, an additional production step can be saved. A corresponding, additional coating apparatus can be dispensed with. The second aspect of the task is solved by a carpet having the characteristics described in Claim 12, namely a carpet possessing an upper layer with filaments and having a thermoplastic material that is applied to the upper layer at the underside of the carpet and that bonds the filaments into the carpet. 5 The carpet according to the invention can be manufactured by at least one of the above mentioned methods. The thermoplastic material that penetrates into the naps and/or filaments of the upper layer at the underside of the carpet provides the carpet with sufficient strength and durability to satisfy standardised load tests. Both felts and tufted carpets may possess a carrier material onto which filaments are applied or into which filaments are inserted. In this embodiment, the thermoplastic material bonds the filaments additionally with the carrier material. Various structures and types of material may be selected for the carrier material. The carrier material may have a woven structure consisting of a plurality of plastic threads oriented in two different directions, with plastic threads oriented in the one direction being alternatingly guided over and under the plastic threads oriented in the other direction, the threads thus being interwoven. The plastic threads may also be yarns. There are holes in the weave pattern. In this preferred embodiment of the carpet the filament bunches are passed through the holes in the weave pattern. This makes it possible to insert the filaments cheaply and simply into the carpet where they are bonded to the weave structure, preferably by hot-melt adhesive. The carrier material may be a closed non-woven material, e.g. a spunbond non-woven. Various types of carrier material may be used. The third aspect of the task is solved by a coating apparatus according to the invention for coating carpets having an upper layer of filaments, said coating apparatus possessing transportation elements for transporting the carpet along the coating apparatus, as well as an applicator for applying thermoplastic material to an underside of the upper layer of the carpet being transported past the applicator. The coating apparatus may be used for at least one of the above-mentioned processes and for coating at least one of the carpet articles in the grey state described above. The coated carpet articles in the grey state range from preferably less than one metre up to several 6 metres in width and they are of any desired length. The coating apparatus is particularly suitable for coating long carpet sheets which are sold as roll products. In the case of the coating apparatus according to the invention, an applicator for thermoplastic material is preferably arranged in such a way that the thermoplastic material flows out below the applicator, preferably from a slot nozzle, and is applied to the carpet that is arranged below the applicator. In this embodiment, no additional means are required to transfer the adhesive from the slot nozzle to the carpet. The carpet that is transported below the thermoplastic applicator can be transported and supported by a coating roller. Preferably an adhesive, in particular a hot-melt adhesive, is applied to the carpet. In a preferred embodiment of the coating apparatus, a first heating element is arranged upstream of the thermoplastic applicator and/or a second heating element is arranged downstream of the thermoplastic applicator in the direction of transport. As described above, the two heating elements, which are preferably IR radiating devices, are used for pre-heating and subsequent heating of the carpet that is passed through beneath the adhesive applicator, in order to improve and support the penetration of the hot-melt adhesive into the underside of the upper layer. It has proved particularly advantageous that the thermoplastic applicator possesses a slot nozzle for applying the thermoplastic material, in particular an adhesive, preferably hot melt adhesive. The slot nozzle may possess a discharge slot for the thermoplastic material, and an inclined entry edge upstream of the discharge nozzle in the direction of transport, and at least one pocket downstream of the discharge slot. Because the entry edge is inclined towards the carpet in the direction of transport, the carpet is transported smoothly beneath the slot nozzle without becoming caught up. The pocket arranged downstream of the discharge opening takes up thermoplastic material and serves also to form a longer contact surface between the thermoplastic material and the carpet being transported past. The pocket allows the naps and filaments to stand up again and become 7 relaxed or to open up again after passing the entry edge. This special shape of the slot nozzle permits particularly solid bonding of the filaments. The invention is described on the basis of exemplary embodiments. The figures show the following: Fig. 1: a diagrammatic cross section through a preferred embodiment of a tufted carpet Fig. 2 a diagrammatic view of a preferred embodiment of a coating apparatus Fig. 3 a cross section through a preferred embodiment of a slot nozzle, and Fig. 4 a cross section through a preferred embodiment of a felt carpet. The carpet 1 according to the invention, as shown in Fig. 1, is a tufted carpet. It is made up of a flat carrier material 2 from which filament bunch portions 3 project at the underside of the carpet. Further filament bunch portions 4 project from the carrier material 2 at the upper side of the carpet. The filament bunch portions 4 at the upper side of the carpet and the carrier material 2 form an upper layer 21 of the tufted carpet. Adjacent filament bunch portions 3 at the underside of the carpet are joined to form carpet loops 5 at the underside of the carpet. Adjacent filament bunch portions 4 at the upper side of the carpet are joined to form carpet loops 6 at the upper side of the carpet. Fig. I shows a single filaments bunch 7, parts of which form filament bunch portions 3 at the lower side and filament bunch portions 4 at the upper side of the carpet. Along its length, the filament bunch 7 is drawn alternatingly from the top downwards and then back again in the opposite direction through the carrier material 2, thereby forming at intervals along its length the carpet loops arranged at the underside 5 and at the upper side 6 of the carpet. At the underside of the carpet a hot-melt adhesive 8 is applied to the filament bunch portions 3 that project from the underside of the carpet, and also to the underside of the carrier material 2. The hot-melt adhesive 8 partially or completely penetrates through the filament bunch portions 3 at the underside of the carpet, thereby forming naps. On the one hand, the hot-melt adhesive 8 bonds the filament bunch portions 3 at the underside of 8 the carpet firmly to the carrier material 2, and on the other hand it increases the intrinsic strength of the filament bunch portions 3 at the underside of the carpet. Because the hot melt adhesive 8 penetrates into the filament bunch portions 3 at the underside of the carpet, it bonds the individual filaments there at the outer periphery of the filament bunch 7 and thus prevents individual filaments from being pulled out of the filament bunch portions 3 at the underside of the carpet. The carrier material 2 has a woven or braided structure (not shown). In it, plastic yarns are arranged in two directions at right angles to each other and run parallel to each other in the two different directions. The plastic yarns running in one direction are led alternatingly over and under the plastic yarns running in the other direction. At the underside of the carpet, a carpet backing can be laminated onto the layer of adhesive once the naps and filaments have been anchored in place. The filament bunches 7 are passed approximately perpendicularly through the carrier material 2 at the penetration points 9. The penetration points I are formed by the holes forming in the braided structure and the filament bunches 7 are passed through these holes. The carpet loops 3 at the underside of the carpet form a space between themselves and the carrier material 2 that is completely filled with hot-melt adhesive 8. Fig. 2 shows a diagrammatic view of a coating apparatus for coating a carpet 1 according to Fig. 1. The coating apparatus possesses an adhesive applicator 10 that is used to apply the hot-melt adhesive to an underside of the carpet 1. The adhesive applicator 10 possesses at its end near the carpet, which in Fig. 2 is the lower end, a slot nozzle 11 through which the hot-melt adhesive is applied over the width of the underside of a carpet I passing through beneath the adhesive applicator 10. The carpet 1 passing beneath the adhesive applicator 10 is supported by a coating roller 12 arranged beneath and in opposite relationship to the adhesive applicator 10. Between the adhesive applicator 10 and the coating roller 12 a small gap is formed through which the carpet I is transported. The spacing between the coating roller 12 and the adhesive applicator 10 can be adjusted by adjusting the height of the adhesive applicator 10. The adjustability of the height of 9 the adhesive applicator 10 is indicated by the double-headed arrow. The adhesive applicator 10 applies the adhesive by means of contact application. The direction of transport of the carpet I is indicated by the two single-headed arrows. In the direction of transport of the carpet 1, upstream of the adhesive applicator 10, the underside of the carpet is uncoated, and in the direction of transport downstream of the adhesive applicator 10, the carpet I is coated with the hot-melt adhesive 8. In the direction of transport of the carpet 1, a first infra-red radiating device 13 is arranged upstream and a second infra-red radiating device 14 is arranged downstream of the adhesive applicator 10. The first infra-red radiating device 13 is used to pre-heat the underside of the carpet. The second infra-red radiating device 14 arranged downstream of the adhesive applicator 10 is used for subsequent heating of the carpet 1. Pre-heating and subsequent heating of the carpet make it possible for the hot-melt adhesive to remain in a fluid state for a longer period of time and thus to penetrate deeper into the filament bunches and/or the structure of the woven material. The depth of penetration can be controlled or influenced according to the intensity of the pre-heating and subsequent heating. In the direction of transport of the carpet 1, further first deflection rollers 15 and second deflection rollers 16 are arranged upstream and downstream of the supporting roller 12 to support the carpet 1 and guide it into the desired position. Fig. 3 shows in detail a slot nozzle 11 according to the invention. The adhesive applicator 10 possesses a slot nozzle 11. The carpet I is transported in the direction indicated by the arrow. In this exemplary embodiment, a sheet of tufted carpet is being processed. However, it is also possible to use the slot nozzle 10 according to the invention to coat sheets of felt, velour or non-woven material. The direction of transport corresponds to the rear view shown in Fig. 2. The slot nozzle 10 possesses a discharge slot 17 that extends across the entire width of the slot nozzle 10. The hot-melt adhesive emerges from the discharge slot. In the direction of transport, an entry edge 18 is arranged upstream of the discharge slot 17. The entry edge slants down towards the carpet I in the direction of 10 transport. Because of the inclined entry edge, the carpet I does not get caught up on the slot nozzle 11. At least one pocket 19 is arranged downstream of the discharge slot, in the direction of transport, at the end of the slot nozzle 10 facing the carpet sheet. Hot-melt adhesive emerging from the discharge slot 17 accumulates in the pocket 19. Because of the longer contact surface with the carpet 1 created by the pocket 19, the hot-melt adhesive is better able to penetrate into the naps and filaments and the spaces between them. At its end facing away from the discharge slot 17 the pocket possesses a cut-off edge 20 for the hot-melt adhesive 8. The felt carpet shown in Fig. 4, like the tufted carpet shown in Fig. 1, can also be manufactured by means of the coating apparatus described above. The felt possesses a pressed upper layer 21 consisting of filaments. The filaments are joined or interlocked with each other by mechanical, thermal or chemical means, but here too the filaments must be bonded in the underside of the upper layer in order to produce adequate durability of the felt carpet. The carpet does not acquire adequate strength until the hot melt adhesive 8 is applied. 11

Claims

1. A method of coating a carpet article (1) in the grey state, which has an upper layer (21) with filaments (7), characterised in that thermoplastic material (8) is applied to the upper layer (21) at the underside of the carpet and the filaments are bonded in the carpet article (1).

2. A method according to claim 1 characterised in that filaments are joined to form a non-orderly assembly or laid assembly to produce the upper layer (21) and the thermoplastic material penetrates into filaments at the underside of the carpet and/or intermediate spaces between filaments.

3. A method according to claim 1 characterised in that the upper layer (21) has a carrier material (2) arranged in a plane of the carpet article and filament bunches (7) are guided transversely through the carrier material (2).

4. A method according to claim 3 characterised in that the thermoplastic material (8) at least partially penetrates into filament bunch portions (3) projecting from the carrier material (2) at the underside of the carpet and/or penetrates into intermediate spaces between filament bunch portions (3).

5. A method according to at least one of the preceding claims characterised in that the upper layer (21) is heated at the underside of the carpet and thermoplastic material (8) is applied to the heated upper layer (21) at the underside of the carpet.

6. A method according to at least one of the preceding claims characterised in that the thermoplastic material (8) is heated after application.

7. A method according to claim 5 or claim 6 characterised in that electromagnetic radiation, in particular IR light, is used for the heating operation. 12

8. A method according to at least one of the preceding claims characterised in that a hot melt adhesive (8) is used as the thermoplastic material.

9. A method according to at least one of the preceding claims characterised in that a slot nozzle (11) is used for applying the thermoplastic material.

10. A method according to claim 9 characterised in that the carpet article (1) in the grey state is transported under an entry edge (18) of the slot nozzle (II) and in that case filaments bend over and stand up again along the width of a pocket (19) of a discharge slot (17) after passing the entry edge (18) for receiving the thermoplastic material.

11. A method according to at least one of the preceding claims characterised in that after the thermoplastic material is applied a carpet backing is laminated on to the underside of the upper layer (21).

12. A carpet comprising an upper layer (21) with filaments, characterised by a thermoplastic material (8) which is applied to the upper layer (21) at the underside of the carpet and which bonds the filaments in the carpet.

13. A carpet according to claim 12 characterised in that the upper layer (21) has pressed filaments and the thermoplastic material at least partially passes through the upper layer (21).

14. A carpet according to claim 12 or claim 13 characterised in that the carrier layer (21) has a carrier material (2) at its underside.

15. A carpet according to claim 14 characterised in that the upper layer (21) has filament bunches (7) passed transversely through the carrier material (2) and thermoplastic material (8) is applied to filament bunch portions (3) projecting from the carrier material (2) at the underside of the carpet. 13

16. A carpet according to claim 15 characterised in that the adhesive (8) at least partially passes through the filament bunch portions (3) projecting from the carrier material (2) at the underside of the carpet and/or partially or completely fills intermediate spaces between filament bunch portions (3).

17. A carpet according to at least one of claims 14, 15 and 16 characterised in that the carrier material (2) has a weave structure comprising a plurality of plastic yarns which are oriented in two different directions and which are woven together.

18. A carpet according to claim 14 characterised in that the carrier material (2) has a non-woven fabric.

19. A carpet according to at least one of claims 12 to 18 characterised in that the thermoplastic material is hot melt adhesive (8).

20. A carpet according to at least one of claims 12 to 19 characterised in that a carpet backing is laminated on to the thermoplastic material directly after the nap and/or filament binding-in operation.

21. A coating apparatus for coating carpet articles in the grey state with an upper layer (21) with filaments comprising: transport elements (12, 15, 16) for transporting the carpet (1) along the coating apparatus, characterised by a thermoplastic material applicator (10) for applying a thermoplastic material (8) to the underside of the upper layer (21) of the carpet article (1) in the grey state which is transported past the thermoplastic material applicator (10).

22. A coating apparatus according to claim 21 characterised by a first heating element (13) arranged upstream of the adhesive applicator (10) in the transport direction. 14

23. A coating apparatus according to claim 21 or claim 22 characterised by a second heating element (14) arranged downstream of the adhesive applicator (10) in the transport direction.

24. A coating apparatus according to claim 21, claim 22 or claim 23 characterised in that the first and/or second heating element (13, 14) is an infrared radiating device.

25. A coating apparatus according to at least one of claims 21 to 24 characterised in that the thermoplastic material applicator (10) has a slot nozzle (11) for applying the thermoplastic material (8).

26. A coating apparatus according to claim 25 characterised in that the slot nozzle (11) has a discharge slot (17) and an entry edge (18) which is inclined in the transport direction relative to the carpet (1) is provided in the slot nozzle (11) upstream of the discharge slot (17) in the transport direction and at least one pocket (19) which is open towards the carpet article (1) is provided in the slot nozzle (11) downstream of the discharge slot (17).

27. A coating apparatus according to at least one of claims 21 to 26 characterised in that thermoplastic applicator (10) is arranged in opposite relationship to a coating roller (12) for supporting the carpet article (1). 15