Binding Strength Improvement in Laminated Carpet Tiles

Abstract

Prior art teaches to apply strands of a hot melt adhesive on a primary backing of a textile product, such as a carpet or carpet tile, before adhering a secondary backing. In some cases, all portions of the strands may not contribute to the adhesion strength. Adjusting the viscosity of the hot melt adhesive may make the strands less flexible as they lay across the irregular features of the backstitching of a primary backing so they provide greater adhesion to the secondary backing. Alternatively, applying the hot melt adhesive to the secondary backing will also be used to create sufficient adhesion. Preferentially, using an air knife to prevent the strands from forming and/or to press the hot melt adhesive into the primary backing may also be used to create sufficient adhesion. These methods provide greater adhesion between the primary and secondary backings with less hot melt adhesive.

Claims

1.-55. (canceled)

56. An apparatus to produce a laminated textile product, comprising: a transport system configured to transport a primary backing across an application roller, wherein a first side of the primary backing contacts the application roller at an application site; and an air knife configured to blow a fluid onto at least a portion of a width of the first side of the primary backing as the primary backing is transported past the application site.

57. The apparatus of claim 56, wherein the application roller is configured to apply an adhesive to the first side of the primary backing at the application site.

58. The apparatus of claim 57, wherein the fluid is configured with a temperature.

59. The apparatus of claim 58, wherein the fluid is configured to provide additional heat to the adhesive.

60. The apparatus of claim 59, wherein the fluid is configured to deliver a filler, wherein the filler is selected from the group consisting of glass, sand, and calcium carbonate.

61. The apparatus of claim 57, wherein the fluid is configured with a temperature and a relative humidity.

62. The apparatus of claim 61, wherein the fluid is configured to provide additional heat to the adhesive and to deliver a filler, wherein the filler is selected from the group consisting of glass, sand, and calcium carbonate.

63. The apparatus of claim 57, comprising laminating rollers configured to laminate a secondary backing with the primary backing.

64. The apparatus of claim 63, wherein the transport system is configured to transport the primary backing at a rate of 10 meters per minute.

65. The apparatus of claim 64, comprising a baffle or diverter.

66. An apparatus to produce a laminated textile product, comprising: an applicator configured to apply a molten adhesive to a first side of a primary backing; and an air knife configured to blow a fluid onto at least a portion of a width of the first side of the primary backing as the adhesive is being applied.

67. The apparatus of claim 66, wherein the fluid is configured to press the molten adhesive into the pores and interstitial spaces of the yarn and the first side of the primary backing.

68. The apparatus of claim 67, comprising laminating rollers configured to laminate a secondary backing with the primary backing.

69. The apparatus of claim 68, comprising a transport system, wherein the transport system is configured to transport the primary backing at a rate of 10 meters per minute.

70. The apparatus of claim 69, wherein the applicator is a roller-style applicator, chosen from the group consisting of a lick roller, a kiss roller, and an application roller with a dosing roller.

71. That apparatus of claim 70, wherein the fluid is configured with a temperature.

72. The apparatus of claim 71, wherein the fluid is configured to provide additional heat to the adhesive and to deliver a filler, wherein the filler is selected from the group consisting of glass, sand, and calcium carbonate.

73. The apparatus of claim 72, comprising a baffle or diverter.

74. An apparatus to produce a laminated textile product, comprising: a roller-style applicator configured to apply a molten adhesive onto a first side of a primary backing; a transport system configured to draw the primary backing across the roller-style application; and an air blade configured to blow a fluid onto at least a portion of a width of the first side of the primary backing as the adhesive is being applied.

75. The apparatus of claim 74, wherein: the fluid is configured with a temperature and a humidity; the fluid is configured to press the molten adhesive into the pores and interstitial spaces of the yarn and the first side of the primary backing; the fluid is configured to provide additional heat to the adhesive and to deliver a filler; the apparatus comprises laminating rollers configured to laminate a secondary backing with the primary backing; and the roller-style applicator is chosen from the group consisting of a lick roller, a kiss roller, and an application roller with a dosing roller.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0046] With the intention of better showing the characteristics of the invention, herein after, as an example without any limitative character, some preferred embodiments are described, with reference to the accompanying drawings, wherein:

[0047] FIGS. 1A and 1B illustrate hot melt adhesive strands on yarn backstitching.

[0048] FIG. 2 illustrates a cross section of a textile product manufactured according to the invention.

[0049] FIG. 3 illustrates the principle of a coating process using a lick roller applicator.

[0050] FIG. 4 illustrates a laminating process incorporating cob-webbing.

[0051] FIG. 5 illustrates a laminating process incorporating an air knife.

DETAILED DESCRIPTION

[0052] FIG. 1A illustrates a tufted primary backing 110 with its associated backstitching 120. The illustration shows a highly flexible strand 130 of polymer adhesive conforming to the characteristics of the back surface 114 of the primary backing 110. That is to say that the strand 130 has sagged into the crevasses between the ridges formed by the yarn backstitching 120. In this illustration, the loops 140 extend away from the front surface 112 of the primary backing 110.

[0053] It may be known to those of skill in the art that the term sagging in this exemplary illustration is not dependent upon gravity. Instead, the strand 130 will conform to the surfaces it encounters as it lays onto them. This being due to the low viscosity of the strand 130 and its cohesive properties.

[0054] When the strand 130 has mass that is not positioned to contribute to the adhesion, mating the primary backing 110 to a secondary backing will not utilize all of the adhesive to secure the primary sheet 110 with the secondary sheet. Instead, some portions of the adhesive will simply stay between the yarn and not contribute to the adhesion between the backing or to binding the tufts.

[0055] FIG. 1B also illustrates a tufted primary backing 110 with its associated backstitching 120. The illustration shows a less flexible strand 150 of polymer adhesive laying atop the characteristics of the primary backing 110 and backstitching 120. That is to say that the strand 150 has not sagged into the crevasses between the ridges formed by the yarn backstitching.

[0056] Mating the primary backing 110 to a secondary backing will utilize all of the adhesive to secure the primary sheet 110 with the secondary sheet. A force applied after mating the backings will force all parts of the adhesive to contact the primary backing 110, the secondary backing, and the portions of the yarn that will be in contact with the secondary backing. Preferably, this will also force the adhesive to infuse into the pores and interstitial spaces near the surfaces of those components as well.

[0057] In both FIGS. 1A and 1B, the relative sizes of the strands may not be illustrated to scale with the other components but are enlarged to illustrate the concepts disclosed herein.

[0058] FIG. 2 illustrates the respective layers of an embodiment of a laminated textile product 200 manufactured according to the inventions taught and disclosed herein. The carpet tile comprises a primary backing 110, which may be a woven sheet, which has been tufted. The yarns 140 extend from the first surface 112 of this first sheet and are secured to the second surface 114 of the sheet. The weight of this primary sheet is typically about 135-153 g/m.sup.2 (not including the tufted yarns). To provide sufficient mechanical stability for use as an end product such as a carpet or carpet tile, the product 200 comprises a secondary backing sheet 210, which may be a needled felt backing. The weight of this secondary sheet may be about 300-500 g/m.sup.2, with a preferred embodiment of about 340 g/m.sup.2. The first and second backing layers are laminated together using a polymer adhesive, which may be a hot melt adhesive applied as layer 250 at a weight of about 170 g/m.sup.2. In this figure, the adhesive layer 250 is illustrated as fused into the primary backing 110, the secondary backing 210, and into the backstitching 220.

[0059] In this illustrative embodiment, the backstitches 220 have been compressed between the primary backing 110 and the secondary backing 210. Some of the adhesive 250 will be absorbed into the pores and interstitial spaces within the primary backing 110, the secondary backing 210, and the backstitches 220.

[0060] In a preferred embodiment, the primary backing 110, the secondary backing 210, the yarn, and the adhesive layer 250 may all be comprised of polyester. In that case, the entire laminated textile product 200 may be recyclable into new polyester products.

[0061] FIG. 3 illustrates the principle of applying the molten hot melt polymer adhesive using a lick roller 301 as an applicator. In this illustrative embodiment the lick roller 301 comprises a metal drum that turns into a trough 303 of molten polymer adhesive 305, by which a layer of adhesive is formed on the outer circumference of the lick roller 301. The adhesive is transported towards the back of the primary backing 330 to be coated with a thin layer of the adhesive where cob-webbing 340 forms between the lick roller 301 and the primary backing 330.

[0062] The primary backing sheet 330 is transported across the top of the turning lick roller 301. As the upper side of the turning lick roller 301 contacts the roller at a contacting site where the cob-webbing 340 forms. In a preferred embodiment, the lick roller 301 turns towards the source of the primary backing 330 being fed. This motion contributes towards a scraping effect allowing the primary backing 330 to scrape the molten adhesive 305 from the lick roller 301 as it is transported.

[0063] The speed with which the substrate is introduced, the speed of the lick roller 301, their mutual contact pressure and surface area, and the viscosity of the compounds determine the final coating weight. This weight may vary between 20 and 1200 g/m.sup.2. The lick roller 301 may have a width of up to about 4.20 meters such that common broadloom carpets may be made using this coating method.

[0064] After the molten adhesive 305 has been applied with cob-webbing 340, a secondary backing 350 may be laminated to the primary backing 330 as illustrated as the sheets pass between laminating rollers 360, 361. The laminating rollers 360, 361 may act as a nip roller to press the backings together. The bound sheets comprise the laminated textile product 370, which may be delivered as a broadloom carpet, or cut into carpet tiles.

[0065] At the site of the cob-webbing 340, the primary backing 330 is moving away from the lick roller 301 with some of the adhesive 305 adhering to it. As the primary backing moves further away from the lick roller 301, the strands stretch and break from the lick roller 301. Once they break from the roller 301, they will lay onto the primary backing 330 to form a texture of fine strands. Advancing the primary backing 330 across the lick roller 301 at speed of about 10 m/min, the strands will typically have a thickness of about 20 m, and a length at break of about 10-15 cm.

[0066] As disclosed herein, an alternative embodiment may be to advance the secondary backing across the applicator so that the molten adhesive is laid onto the secondary backing with cob-webbing. After that, the secondary backing may be mated to the primary backing in much the same way as illustrated in FIG. 3. By applying the molten adhesive to the secondary backing, all of the mass of the adhesive will contribute towards the adhesion between the primary and secondary backing. Also, some of the adhesive will bind the backstitches to the secondary backing so that the bind between the backstitches and the secondary backing, along with any adhesive that seeps into the primary backing and the backstitches, will contribute towards binding the tufts in place. In some places, the adhesive will be infused into the primary backing, the secondary backing, and the backstitching to contribute towards the lamination and tuft binding strengths.

[0067] If the molten adhesive 305 is applied to the primary backing 330 as illustrated in FIG. 3 through cob-webbing 340, but the end product 370 fails a delamination test or a tuft bind test, then the strands of the molten polymer adhesive may be too flexible such that they conform to the crevasses and ridges made by the backstitching on the bottom surface of the primary backing 330, as is illustrated in FIG. 1A. As disclosed herein, this may be addressed by increasing the viscosity of the molten adhesive to stiffen the strands. When that happens, the strands will not fully conform to the topology of the back of the primary backing, but will lay across the tops of the ridges formed by the backstitching so that all of the mass of the polymer adhesive will contribute to the adhesion as illustrated in FIG. 1B.

[0068] One method of improving the viscosity of the hot melt adhesive is to react the polymers with a chain extender to increase the average molecular weight of the adhesive. Additionally, the viscosity of the hot melt adhesive may be improved with antioxidants and stabilizers.

[0069] One way to prepare a molten hot melt polymer adhesive is to take pellets of the adhesive and pass them through an extruder, which grinds them together and compresses them so that the pellets become molten from the friction developed within the extruder. The molten adhesive may then be transported to an applicator, such as the trough in a lick roller applicator, or as the puddle in the application and dosing rollers applicator. As the pellets are added to an extruder, antioxidants and stabilizers may be added with them at a rate sufficient to increase the viscosity such that less flexible strands of the adhesive are formed during cob-webbing.

[0070] Another way to prepare molten hot melt polymer adhesive is to take an existing fluid of the adhesive and bring it to a temperature sufficient for delivering to an applicator. In this, antioxidants and stabilizers may be added with the polymer fluid at a rate sufficient to form less flexible strands of the adhesive from cob-webbing. The determination of the weight-average molecular weight of polymers may be found by testing with the ASTM D4001-20 standard.

[0071] Those of skill in the art will also know of ways to react the polymer adhesive with a chain extender to increase the average molecular weight of the adhesive. In one embodiment, the pellets of polymer adhesive may be prepared in advance so that long-chain polymers of adhesive will be ready for use in pellet form so it may be extruded with or without antioxidants and stabilizers onto a primary or secondary backing.

[0072] In some embodiments, a seed batch of the polymer adhesive may be reacted with a chain extender and produced as pellets and set aside. Then, when a production run is started, the seed batch of pellet may be metered into an extruder along with unreacted adhesive pellets. In this way, only a portion of the adhesive has been reacted with the chain extender but the overall molten adhesive will have a higher viscosity than a molten adhesive prepared without any of the seed batch. In this embodiment, only a portion of the chain extended adhesive need be mixed with the adhesive that has not been reacted with a chain extender to sufficiently raise the viscosity of the overall molten adhesive to achieve acceptable results for lamination and tuft bind strengths.

[0073] In other embodiments, a polymer that is different from the polymer adhesive may be added to the polymer adhesive to increase the viscosity of the polymer adhesive. That is to say that the viscosity of the molten polymer adhesive may be increased by adding a long chain polymer to it, even if the long chain polymer does not contribute to the lamination or tuft bind strength.

[0074] In some embodiments, the secondary backing 350 may be a needled felt product. In those embodiments, the needled felt product may have ridges and crevasses similar to those presented by the backstitching of the primary backing 330. In those embodiments, the strands of molten polymer adhesive may conform to the topology of the secondary backing 350 such that some portions of the mass of adhesive 305 may not fully contribute towards the adhesion between the backings. Rather than adding more adhesive so that the end product 370 passes a delamination test and a tuft binding test, the flexibility of the strands may be reduced by increasing the viscosity of the molten polymer as disclosed and taught herein.

[0075] FIG. 4 illustrates another embodiment for applying molten polymer adhesive with cob-webbing. In this embodiment, a puddle of molten adhesive 405 sits between an application roller 401 and a dosing roller 402. A gap between the application roller 401 and the dosing roller 402 may be narrowed or widened to allow less or more adhesive to carry through to be applied to the back of the primary backing 430. After the primary backing 430 contacts the application roller 401, cob-webbing 440 occurs which applies the strands of adhesive 405 to the primary backing 430. After the adhesive 405 is laid onto the primary backing 430, the primary backing 430 and the secondary backing 450 are mated and secured together with laminating rollers 460, 461 to produce a laminated textile product 470.

[0076] As disclosed herein, an alternative embodiment may be to advance the secondary backing across the applicator so that the molten adhesive is laid onto the secondary backing with cob-webbing. After that, the secondary backing may be mated to the primary backing in much the same way as illustrated in FIG. 4. By applying the molten adhesive to the secondary backing, all of the mass of the adhesive will contribute towards the adhesion between the primary and secondary backing.

[0077] Also, if the molten adhesive 405 is applied to the primary backing 430 as illustrated in FIG. 4 through cob-webbing 440, but the end product 470 fails either a delamination test or a tuft binding test, then the strands of the molten polymer adhesive may be too flexible in that they conform to the crevasses and ridges made by the backstitching on the bottom surface of the primary backing 430, as is illustrated in FIG. 1A. As disclosed herein, this may be addressed by increasing the viscosity of the molten adhesive to stiffen the strands. When that happens, the strands will not fully conform to the topology of the back of the primary backing, but will lay across the tops of the ridges formed by the backstitching so that all of the mass of the polymer adhesive will contribute to the adhesion such as is illustrated in FIG. 1B.

[0078] The secondary backing 450 may be a needled felt product. In that case, it may have ridges and crevasses similar to those presented by the backstitching of the primary backing 430. Again, if the end product 470 fails a delamination test or a tuft binding test, rather than adding more adhesive 405 to the backing, the adhesion between the primary backing 430 and the secondary backing 450 may be improved by changing the viscosity of the adhesive 405 so that the strands of molten polymer become more rigid.

[0079] In all of the embodiments disclosed and taught herein, the laminated textile product may be recyclable. The yarn, the primary and secondary backings, and the adhesive may be made of a recyclable polymer. That is to say that the adhesive may be made of a recyclable polyester polymer such as, but not limited to, PET and/or PET and coPET.

[0080] Turning now to a more preferred embodiment, an embodiment of the use of an air knife to seat the hot melt adhesive is illustrated in FIG. 5. In this illustrative embodiment, an air knife 580 is positioned near to the primary backing 550 after adhesive is applied from the laminating roller 501.

[0081] An air knife, which may also be known to those skilled in the art as an air blade, may be configured to extend across the width of the laminating apparatus 500 such that the entirety of the area of contact between the primary backing 550 and the application roller 501 is impacted by the air being jetted from the air knife.

[0082] As is similar to the process 400 of the embodiment of FIG. 4, the primary backing 550 may be drawn across the application roller 501 to transfer adhesive 505 to the back of the primary backing 550. The amount of adhesive 505 may be configured by adjusting the gap between the application roller 501 and the dosing roller 502.

[0083] Positioned just after the adhesive is transferred is an air knife 580 configured to blow a gas, such as air, across the width of the primary backing 550. The air being blown from the air knife 580 may be directed into the space between the primary backing 550 and the application roller 501. The force of the air may be such that no cob-webbing strands are formed between the primary backing 550 and the application roller 501. Instead, the air will push the transferred adhesive 505 deeper into the crevasses and ridges of the backstitching and into the pores and interstitial spaces of the yarn and primary backing 550 where it will eventually cure and add more strength against delamination and tuft pull.

[0084] In a first embodiment, the air knife 580 may be configured to continually expel a sufficient volume of gas across the width of the laminating apparatus 500 to prevent cob-webbing. In another embodiment, the air knife 580 may be configured to continually expel a sufficient volume of gas across the width of the laminating apparatus 500 to prevent cob-webbing and to press the molten adhesive 505 into the pores and interstitial spaces of the yarn and primary backing 550.

[0085] In a preferred embodiment, the gas may be air. Air may be compressed near the laminating apparatus 500 and driven immediately through the air knife 580. In other embodiments, the gas may be from cylinders and may be configured with inert and/or reactive gases. In this, it may be preferable to use a reactive gas to react with a component to provide a desired property. For example, the gas may be a composition of nitrogen and chlorine. The amount of chlorine in the nitrogen may be configured to react with a portion of the adhesive, the yarn, the primary backing, or combinations thereof. In another embodiment, the gas may be entirely inert. For example, the gas may be composed of nitrogen or carbon dioxide to prevent the molten adhesive 505 from being oxidized.

[0086] The gas from the air knife 580 need not only apply pressure to drive the adhesive 505 into the crevasses and ridges of the backstitching and into the pores and interstitial spaces of the yarn and primary backing 550, but may also be configured with other environmental properties. For example, the gas may be configured with a temperature and/or with a humidity.

[0087] A humidity configured within the gas may add or remove moisture from the adhesive spread across the back of the primary backing. Blowing arid air across the adhesive 505 would remove and/or eliminate any moisture that may condense upon the adhesive 505 before it is mated and secured together with the secondary backing 530 between the laminating rollers 560, 561. In a preferred embodiment, the humidity configured in the gas may be held constant throughout the running of the laminating apparatus 500. For example, when the ambient air has a high relative humidity, the air from the air knife 580 may be arid to offset that. However, when the ambient air has a low relative humidity, the air from the air knife 580 may be set to blow in air with a higher relative humidity. In this way, the relative humidity of the air contacting the adhesive 505 from the time that it is applied onto the primary backing 550 from the application roller 501 until it is mated and secured to the secondary backing 530 between the laminating rollers 560, 561 will remain constant regardless of any ambient changes outside of this space.

[0088] The gas may also be configured with a temperature. In a first aspect, the temperature of the gas may counteract seasonal and/or daily variations in ambient conditions. For example, the facility housing the laminating apparatus 500 may be warmer in the summer and colder in the winter. Similarly, it may be cooler in the morning and hotter in the afternoons. Regulating the temperature of the gas from the air knife 580 can offset these inconsistencies to make the laminated textile product 570 have consistent tuft bind and delamination strength throughout any ambient condition changes.

[0089] In a second aspect, configuring the temperature of the gas may provide additional heat to the adhesive 505 after it leaves the application roller 501 until the time that the primary backing 550 is mated and secured to the secondary backing 530 between the laminating rollers 560, 561. In the time that the adhesive 505 leaves the application roller 501 until the time that the primary backing 550 is mated and secured to the secondary backing 530 between the laminating rollers 560, 561, the adhesive is cooling. Having the temperature controlled air remain in contact with the adhesive in the section between when the adhesive 505 is applied by the application roller 501 until the time that the primary backing 550 is mated and secured to the secondary backing 530 between the laminating rollers 560, 561 may be done by positioning a baffle or a diverter within the laminating apparatus 500 such that the gas that has been blown by the air knife 580 to prevent the formation of cob-webbing strands and to press the molten adhesive 505 into the pores and interstitial spaces of the yarn and primary backing 550 may then be directed towards the section of the apparatus 500 between when the adhesive 505 is applied by the application roller 501 until the time that the primary backing 550 is mated and secured to the secondary backing 530 between the laminating rollers 560, 561.

[0090] In another embodiment, the temperature of the gas from the air knife 580 may be higher than the temperature of the molten adhesive 505. This may be done to prevent degradation of the molten adhesive before it is applied through contact with the primary backing 550, but is then heated by the gas from the air knife 580 to a temperature that will provide desirable bonding and binding properties.

[0091] The temperature-controlled gas need not just dissipate after being applied to eliminate the cob-webbing strands or after being applied to the section of the apparatus 500 between when the adhesive 505 is applied by the application roller 501 until the time that the primary backing 550 is mated and secured to the secondary backing 530 between the laminating rollers 560, 561. Instead, the temperature-controlled gas may be further directed after it has achieved one or both of those objectives. In another embodiment, additional conduits maybe installed such that the temperature-controlled gas may be directed to flow around the laminated textile product 570. This may be to heat or cool the laminated textile product 570 at a slower or faster rate than would be achieved by only exposing the laminated textile product 570 to ambient air after it has been mated and secured together by the laminating rollers 560, 561. In one aspect, this may be used to anneal the adhesive so that it does not cool too quickly which may make the adhesive brittle within the laminated textile product.

[0092] In an envisioned embodiment, the air knife is not limited to blowing only gas. In this embodiment, particulate matter may be entrained in the gas to be delivered onto the adhesive 505 while it is still hot. With enough force from the jetted gas, the particulate matter may be deeply embedded into the adhesive 505. This may be useful to deliver a filler such as, but not limited to: glass, sand, and calcium carbonate. The jetted particulate matter may also be useful in preventing cob-webbing in that the particles may sever the strands and thus prevent the formation of the strands while less pressure is used to drive the gas from the air knife.

[0093] The present invention is in no way limited to the herein above-described embodiments. On the contrary many such improvements to application of adhesives may be devised and applied according to various variations of the inventions disclosed and taught herein, without leaving the scope of the present invention.