CA1071989A

CA1071989A - Backing of carpets

Info

Publication number: CA1071989A
Application number: CA257,347A
Authority: CA
Inventors: Peter V. E. Davies; Barry T. Kirby; Alexander Ferris
Original assignee: ILCOR GmbH
Current assignee: ILCOR GmbH
Priority date: 1975-07-24
Filing date: 1976-07-20
Publication date: 1980-02-19
Also published as: CH617304GA3; GB1552414A; NL7608042A; CH617304B; JPS5215671A; FR2318974A1; IE44155L; AU513169B2; SE7608216L; LU75439A1; IT1066031B; AU1598776A; DE2632569A1; IE44155B1; FR2318974B1; BE844497A; DK335476A

Abstract

A B S T R A C T

A tufted carpet or similar non-woven floor covering has a pile surface carried by a primary backing, an anchor coat to bind the pile into the backing, a resilient layer of foam laminated to the anchor coat and an at least partly fibrous secondary backing laminated to the foam. The thickness of the foam is in the range of 1.0 to 4.0 millimetres and the secondary backing is preferably laminated directly to the layer of foam. The main constituent of the foam may be styrene butadiene rubber and the foam may be extruded by a filler or fillers.
The floor covering is produced by a method which includes the step of bringing the layer of foam and the secondary backing into contact with one another while the foam is still in a moist state so as to cause a degree of mutual penetration between these two layers and then completing the lamination by the application of heat to cure and dry the foam.

Description

lL07~9~9 mis invention relates generally to non-woven floor coverings having a pile surface carried by a primary bac~ing. It is particularly concerned with tu~ted carpets and ~or simplicity will be described in 5. terms of such carpets without prejudice to its more general applicationO
In the finishing of tufted carpets, a foam backing which may be of 2.5 to 6 millimetres in thickness is normally applied. This renders thê look of the 10. completed carpet noticeabIy dif~eren-t ~rom that o~ a woven carpet, and a certain degree o~ sales resistance to the appearance of a foam-backed tufted carpet still remainæ.
The interlockin~ struc-ture of a woven carpet, 15. e.g. of the Axminster of Wilton ~ype, where the pile yarn is incorporated by the weaving together of the backing yarns needs only the application of a starch or latex in a simple finishing process to give the carpet a good finish and handle. On the other hand, tu~ted 20. carpet requïres greater attention in finishing i~ an acceptable product is to result~ As mentioned above, a foam-backed carpet is generally regarded as inferior, but the alternatives to this which have so far been adopted lead to no real improvement. Thus a latex or 25. similar substance whic~ may be applied to anchor the j~
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tufts into the primary backing does little to improve the handle and dimensional stabili~y of the carpetO
In a subsequent stage in ~inishing, therefore, a secondary backing9 which may be o~ woven or non-woven 5. material and in which jute and/or po~ypropylene are commonly present, is sometimes laminated to the latexed, partially finished carpet. r~his serves to improve dimensional stability, appearance and handle, but, particularly with relatively low pile weights, the 10. addition of the secondary backing results in a carpet which, by comparison wi-th woven carpet~ still remains light and flimsy and thus lacking in bulk and therefore apparent value.
The secondary backing just described is applied 15. as a substitute for a foam backing, but according to the present invention a secondary-backing is applied in addition to and externally of a foam layer, thus leading to the double advantage of covering up the fo~m layer with its connotations o~ inferiority to give an 20. appearance similar to that of a woven ca~pet and, as a result o~ the additional layer~ considerably increased firmne~s, dimensional stability, bulk resiliency and handle.
E~pressed in more specific termsj a tu~ted 25. carpe-t or other non-woven floor covering in accordance with the in~ention has a pile sur~ace carried by a primar~ backing, an anchor coat to bind the pile into .
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`the primary backing, a resilient layer of foam laminated to the anchor coat and a woven or non-woven secondary backing laminated directly to the foam so tha-t its outer surface lies wholly outside that of the foam. The main advantages 5. of such a structure as mentioned above are particularly applicable to tufted carpets and other non-woven floor covering~s having comparatively low pile weights, giving them improved performance and wider sales appeal. There is also the additional advantage of not requiring a 10. separate underlay when the carpet is fitted in position, although an underlay may be used if required.
For best results, the thickness of the layer o~ Eoam should be in the range oE 1.0 to ~.0 millimetres, the thickness within this range being dependent on tha 15. properties and effect re~uired and the characteristics of the other components of the carpet. Generally speaking, best results are achieved for a thickness between 1.5 and

2.0 millimetres. For a thickness less than 1.0 millimetre, little advantage is gained from the additional complication 20. of including the foam and for thicknesses greater than 4.0 millimetres, the additional advantage is not commensurate with the added cost. Whatever its thickness, the foam may be pigmented to the colour of the secondary backing to assist in the visual simulation of a woven carpet.
25. The lamination of the secondary backing to the foam can be achieved as a result of a direct bond between .. - ~ . . . ~ .

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7~9~9 the two which may result from bringing the two layers into contact with one another while the layer of foam is still in a moist condition so as to cause a degree of mutual penetration between the two layers. The bond between the two is then completed by the application of heat to cure and dry the foam. The mutual penetratlon is made possible by the at least partly fibrous nature of the secondary backing so that the foam can penetrate between the fibres and, to a certain extent, any projecting fibres can extend into the foam. Such a direct bond leads to a basic laminated structure compris:ing just four layers, i.e. the pile-carrying primary backing, the anchor coat, the foam layer and the secondary baclcing.
Apart ~rom its thickness discussed above, the 15. nature of the foam used is o major importance in obtaining the required properties of resilience. Generally speaking, the foam should comprise a rubber or a rubber-like material and best results are obtained when the foam is latex-based.
Apart from providing the rubber-like features within the 20. compound, the use of a latex-based material provides adhesive properties and moreover for purposes of economy the latex can be extendecl by the use o~ fillers. The best of the latex-based materials are in the form of synthetic rubbers, o~ which that preferred is styrene butadiene 25. rubber, the styrene content being of significance in providing the desired properties referred to above.

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- 107~11 9~391 The foam used may be either of the gel or no-gel type, either synthetic or natural, the only importan-t difference between the two lying in the processing rather than in the final properties. The curing of a no-gel foam is in effect a drying process, for the cured foam structure is not wholly present until the foam is dried.
Expansion takes place as air passes through the cellular structure during the drying process. The curing of a gel foam on the other hand, is a vulcanising process and the foam thickness is reduced during the process.

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The basic curing treatment for both types of foam is t~e same, however, involving preliminary drying, e.g.
by means of in~ra-red radiation, followed by curing in an oven. For the reason just explained, a no-gel foam 5. will expand between 10 and 20% during curing. merefore, in order to achieve a cured -thickness of 1.5 mi~limetres, a gel foam will need to be applied in thicknesses of approximately 1.65 to l.80 millimetres and a no-gel foam will be applied in thicknesses o~ approximately 10. 1.25 to 1.375 millimetres.
Only a thin layer o~ the anchor coat is required and in order to increase its volume at the time o~ application and thus to assist in even application, the anchor coat is also pre~erably in the 15. ~orm o~ a ~oam which collapses as it is dried so that, in the finished carpet, the anchor coat is present in the ~orm of a collapsed ~oam. As with t~e foam layer, the anchor coat is preferably latex-based and may be a carboxylated latex. As with the main foam layer, the 20. preferred material is a styrene butadiene latex.
As previously mentioned, the secondary backing ls an at least partly ~ibrous material which is pre~erably woven although non-woven materials are also suitable. I~ a woven ~abric is used, it is import~nt that 25. it should be closely woven and not open or sleazy. This - material pre~erably -includes a proportion of jute yarns - , .- ., .
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~0 7~9 ~g and, generallyg speaking, bes-t results are obtained with a combination of jute yarns and polypropylene which may be in -the form of yarns or tapes. m e use of polypropylene is not essential and this material may be replaced by, for example, a polyester, an acrylic ~ibre, a polyamide fibre, a polyethylene ~ibre or a cellulosic fibre.
If polypropylene or one of the alternatives just mentioned is used withou-t any jute at all, at leias~ a proportion should be fibrous, e.g. either a staple yarn or fibrillated, 10. so as to provide a somewhat hairy texture which ~acilitates a direct bond with the ~oam layer.
In a pre~erred type of woven fabric used ~or the secondary backing, the we~t yarns are o~ ~ute which are pre~erably o~ a natural shade to æsist in the 15. simulation of a woven carpet. ~ute ~y its nature is, -of course, a hairy yarn. m e warp is consti-tuted by polypropylene tapes~ two out of three o~ which are un~ibrillated while the third is fibrillated ~or the reason mentioned above. I~ the ~abric is to consis-t 20. wholly o~ synthetic materi~ls, the we~t may also consist o~ staple yarn or similar tapes o.~ polypropylene or one of the previously mentioned alterna~ ves.
In order to produce a direct bond between the secondarr baoking and the layer of ~oam, a method 25. o~ production in accordance with the invention includes the step of bringing the layer o~ foam and the secondary . ~ .

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backing into contact with one another without the application of external pressure while the foam is still in a moist state so as to cause a degree of mutual penetration between these two layers sufficient to produce a direct bond between them but insufficient to lead to the presence of foam at the outer surface of the secondary backing, and then complet-in~ the lamination by the application of heat to, cure and dry the foam. In order to achieve intimate contact between the layer of foam and the secondary backing, the foam needs 10. to be evenly spread and the thickness of the layer carefully regulated. This may be achieved by means of a doctor roller ora doctor blade, preferably the former.
Preferably, the layer of foam is Eormed on top oE
the anchor coat on the side of the primary backing away rom 15. the pile and the secondary backing is then laid on top of the moist foam layer. This completes the four-layer structure which is then subjected to heat to cure and harden the foam and thus complete the lamination. Generally speaking, it is preferable to dry the anchor coat before 20. application of the foam layer, but it is also possible to apply the wet foam to the wet anchor coat ancl to dry both together.
An alternative method of bringing the layer of 25. foam into contact with the secondary backing while the foam is still in a moist state is to apply the layer of foam to the secondary backing rather than to the dry anchor coat and then to laminate the two layers :3 . . ; ., . ~ .. .

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~719~9 by the application of heatO The combination o~ foam plus the secondary backing then has to be laminated to the primary backing, the anchor coat then per~orming the dual function of pile locking and ~orming the 5. bond between the ~oam layer and the primary backing7 thus again giving a four-layer structure.
When proceeding in accordance with the preferred method by forming the layer of ~oam on top of the dry anchor coat and laying the secondary backing on top of 10. the moist ~oam layer, the secondary backing may be conveniently passed around a laminating device such as a roller mounted immediately above the sur~ace of the ~oam layer so as to lay the secondar~ backing on top o~
the ~oam wlthout the application of pressure as the foam 15- passes beneath the laminating device.
A method in accordance with the invention will ~ow be described in more detail, by way of example, with re~erence to the accompanying drawings, in which:- ;
20. Figure l is a diagrammatic view showing a ! complete production line, Figure 2 is a detailed view to an enlarged scale showing -the ~ormation o~ a layer of ~oam and the application o~ a secondary backing to ~he foam; and 25. Figures 3 and 4 are diagrammatic sectional views showing the laminated structure o~ alternative ~orms o~ carpet.

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Turning ~irs-t to Figure 1, unbacked carpet 1 drawn from a source o~ supply (not shown) consis-ts o~
a tufted primary backing and may be optionally pre-printed. Other types o~ non-woven floor covering may 5. also be treated by the same general process. A~ter passing around a sequence of rollers 2, 3, 4 and 59 the unbacked carpet passes to an applicator 8 where a layer of anchor coat is applied, by means of a lick roller and a i - doctor blade. The anchor coat is, of course, applied 10. to the untu~-ted side of the primary backing which is downmost at this point, but after passing around a further roller 10 the untu~ted side carrying the layer o~ anchor coat is uppermost. The anchor coated prima~y back~ng, shown as 12, passes to a stenter ll~ on Which it 15. is supported while passing beneath infra-red heaters 15 mounted within an enclosure shown generally as 16.
The heaters 15 dry the anchor coat and bond the tufts firmly in ~o~ition in the primary backing. As illustrated, the stenter 14 terminates at a roller 17, but if required 20. a single stenter may extend along the whole of the production line shown in Figure 1.
; A~ter leaving the stenter 14, the-~anchor coated carpet 12 passes in a generally U-shaped ;~
loop beneath an inspection platform 1~ which gives the 25. operator close access to the next stage of the process which is the application of the foam.
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15. To the right of the doctor roller 25 is a laminating roller 30 around which secondary , ,. backing.. material .32 passes into contact with the - ~ ''' upper surface of the foam layer 23, being drawn from a supply station 34 seen in Figure 1. The roller 30 ". 20.,.~ may be silicone coated and is ad3ustable in a , -- .-~
vertical direction, being adjusted in accordance with the thickness o~ the foam layer 23 so as to lay the . - .~ ,,........ . secondary.,backing.m&~er~al 32 on top of ~he wet layer of foam without the application of any pressure to 25. the carpet structure. Immediately after this, the - ~2 --.' ., ~..... . .
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carpet is picked up by a main stenter 33 starting at a roller 35.
m e carpet, now shown as 36, comprises its ~ull complement of ~our layers, i.e. primary 5. backing9 anchor coat, foam layer ~d secondary backing and is carried by the main stenter over a supporting table 37 and then between ~ pair of smoothing rollers 38 arranged above and below the carpet respectively.
These rollers are also adjustable in accordance 10.~ with the thickness of the various layers and their function is both to correct any irregularities in the outwards facing surface of the carpet struct~e 36 and to maintain uninterrupted contact be-tween the secondary backing 32 and the upper surface o.~ the foam 15. layer Z3 without applying any appreciable pressure to the carpet structure. m e rollers are situated a few feet to the right of the laminating roller 30, between five and ten feet being a typical value for the spacing.
20. While the carpet travels over this distance -the ~econdary backing material 32 settles down and sinks ~lightly into the ~oam layer 23-while the ~oam penetrates the structure o~ the secondary backing material, thus providing a degree of mutual penetration.
25. While still supported by the stenter 33 and the table 37 the carpet passes beneath infra-red , ~ . . .

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heaters 40 mounted within a heating chamber shown generally at 41~ The e~fect of this heating depends on whether a gel or no-gel foam is used, but in either case, the foam becomes set and a bond is established 5. between the foam layer 23 and the secondary backing 32. A bond is also established between the.~oam layer 2~ and the anchor-coated primary backing, this being assisted by the uneven nature of the anchor-coated surface due to the base ends of the tu~ts 10. which extend through the primary backing.
Finally, the carpet passes into an oven 45 -where the ~oam is cured and dried ~emperatures in the heater 41 and the oven 45 depend on a ~ariety o~ factors such as the materials o~ the carpet, the 15. speed o~ travel and the length o~ these two enclosures, but in general the temperature of the heater 41 is slightly higher than that of the oven 45,~ but~the dwell time in the oven will be greater than under the heater 41.
20. The completed carpet is then removed ~rom the stenter and taken away ~y a s~stem o~
rollers to a storage station (not shown). While ~e-use-o~ in~r~red-heaters-is~ us-trated-a~--bel-ng the preferred arrangeme-nt, this is not essen-tial and 25~. the inltial setting of the foam can occur during the ~irst part of its travel through the over 4.5.

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Figures 3 and 4 are diagrammatic illustrations o~ a cross section jo~ two typical const~uctions o~
carpet produced in accordance with the invention7 that shown in Figure 3 having a cut pile of low density, 5. while that shown in Figure 4 has a looped pile of higher density. In each of the two constructions, the pile is shown as 50, the primary backing as 51, the anchor coat as 52, the foam layer as 5~ and the secondary backing as 54. This constitutes the basic 10. four-layer construction in accordance wi-th the present invention. In other words, -there is a direc-t bond between the foam 53 and the secondary backing 54. As described previously, this can be modified by the inclusion of a layer of adhesive between the ~oam 52 15. and the secondary backing 53. In these circumstances, the process illustrated in Figure 1 needs to be modified in -that the secondary backing 32 is not fed into contact with the wet foam, but the foam is dried and cured as already described, a layer of adhesive i5 applied 20. either to the foam or to the secondary backing in a similar manner to the application o~ the anchor coat at 8, the secondary backing 32 is -then fed into contact with the layer of adhesive and the final, five~
layer structure is then again heated to dry ~he adhesive.
25. Examples will now be given of the different form~lations ~or use in a method as carried out by use of ~he apparatus just described.

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~L~71g8g If the modified process is used in~olving curing of the foam layer prior to lamination, the -- ~ following is an example of a suitable adhesive~

EXAMPLE IV - ~DHESIVE FOR~ULATION IN DRY WE~GHTS
.
Application (ei~her ~oamed or unfoamed~ at 136-407 ~m/m2 . . .
Total solids content 50 to 60Yo Natural rubber100 parts Base latex Caustic potash0.2 parts Stabil:iser (25% solution) Antioxidant 1.0 par-ts Potassium oleate1.0 parts Sur~actant - foaming agent Z~nc Oxide ~ ~~ 2.0 parts Curative'' x Sulphur 1.5 parts Curative Zinc diethyl 0.2 parts Accelerator d-i~hi-ocarbamate-Zinc mercapto 0.1 parts Accelerator ~ :
benz thiazole Ca Co3 or china clay O - 75 parts Filler Polyacrylate '~'0.1 parts mickener' Many other types of adhesive form~ation may be used such~as a filled carboxylated styrene butadiene a~esive.

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m e examples given above are all suitable for a wide range of non-woven ~loor coverings having pile surfaces of varying weights c~d materials. As mentioned originally9 most advantciges are obtained àt 5. comparatively low pile weights. The secondary backin~7 however, needs to be selected in accordance with the requirement mentioned previously and an example of this is as follows:-10. EXAMPLE V - SECONDARY BACKING F~BRIC

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Closely woven construction comprising pol~propylene warp and ~ute we~t. The warp sequence comprises three polypropylene tapes, two of buf~ delustered, one white ~ibrillated and delustered.
15. We~t spun jute preferably o~ a na-tural shade.
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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A non-woven floor covering having a pile surface carried by a primary backing, an anchor coat to bind the pile into the primary backing, a resilient layer of foam laminated to the anchor coat and a woven or non-woven secondary backing laminated directly to the foam so that its outer surface lies wholly outside that of the foam.

2. A non-woven floor covering according to claim 1 in which the secondary backing is at least partly fibrous.

3. A floor covering according to claim 1 in which the thickness of the foam is in the range of 1.0 to 4.0 millimetres.

4. A floor covering according to claim 3 in which the thickness of the foam is between 1.5 and 2.0 millimetres.

5. A floor covering according to claim 1 in which the foam comprises a rubber or rubber-like material.

6. A floor covering according to claim 5 in which the foam is latex based.

7. A floor covering according to claim 6, in which the main constituent of the foam is synthetic rubber.

8. A floor covering according to claim 6, in which the main constituent of the foam is styrene butadiene rubber.

9. A floor covering according to any one of claims 5 to 7 in which the foam is extended by a filler or fillers.

10. A floor covering according to claim 1 in which the anchor coat is in the form of a collapsed foam.

11. A floor covering according to claim 1 or 10 in which the anchor coat is latex based.

12. A floor covering according to claim 10 in which the anchor coat is extended by a filler or fillers.

13. A floor covering according to claim 1 in which the secondary backing is a woven material, including a proportion of jute yarns.

14. A floor covering according to claim 1 in which the woven material includes at least a proportion of polypropylene.

15. A floor covering according to claim 14 in which the polypropylene is in the form of tape.

16. A floor covering according to claim 15 in which at least a proportion of the tape is fibrillated.

17. A floor covering according to claim 1 in the form of a tufted carpet.

18. A method of producing a floor covering having a pile surface carried by a primary backing, an anchor coat to bind the pile into the backing, a resilient layer of foam laminated to the anchor coat and a woven or non-woven secondary backing laminated to the foam, which includes the step of bringing the layer of foam and the secondary backing into contact with one another without the application of external pressure while the foam is still in a moist skate to as to cause a degree of mutual penetration between these two layers sufficient to produce a direct bond between them but insufficient to lead to the presence of foam at the outer surface of the secondary backing and then completing the lamination by the application of heat to cure and dry the foam.

19. A method according to claim 18 in which the foam is evenly spread and the thickness of the layer regulated by means of a doctor roller or blade.

20. A method according to claim 18 in which the layer of foam is formed on top of the anchor coat on the side of the primary backing away from the pile and the secondary backing is laid on top of the moist foam layer.

21. A method according to claim 20, in which the anchor coat is dried before the application of the layer of foam.

220 A method according to claim 20 in which the secondary backing is passed around a laminating device mounted immediately above the surface of the foam layer so as to lay the secondary backing on top of the foam without the application of pressure as the foam passes beneath the laminating device.

23. A method according to claim 22 in which the laminating device is a roller.

24. A method according to claim 20 in which the laminated assembly is passed through a smoothing arrangement after -the secondary backing has been laid on top of the foam.

25. A method according to claim 24 in which the smoothing arrangement comprises a pair of rollers.

26. A method according to claim 20 in which the assembly is held by a stenter during the application of the foam layer, the introduction of said secondary backing and the subsequent heating.