Patent Application
20180320310
The present invention pertains to a method to manufacture a textile product, in particular a carpet product such as broadloom carpet, carpet tiles, mats and rugs, comprising a first sheet having polyamide yarns fastened to this sheet to form a pile thereon, the method comprising providing the sheet, stitching the polyamide yarns through the sheet to form the pile on a first surface of the sheet, the pile extending for a predetermined length from this first surface, and to form loops of the yarns at a second surface of the sheet, and fastening the yarns to the sheet by creating a layer of fused material on the second surface of the sheet using heat. The invention also pertains to a method to use a textile product obtained with the new method, the textile product itself and a device for applying the said method.
Traditionally textile products such as carpet products are made by firstly forming an intermediate material of yarns being stitched, typically tufted or woven, into a primary backing (the first sheet), and optionally cut, to form a pile on top of the first surface this primary backing, and loops of the yarns on the second surface (the back side) of this backing. In such an intermediate layer, the yarns can be pulled out of the backing by using a light pulling force, for example by pulling on a yarn by hand. In order to create a textile product wherein the yarns are adequately mechanically anchored in the primary backing, a layer of fused material may be created on the back surface of the primary backing. The fused layer may be a simple molten and thereafter solidified thermoplastic material (such as hot melt adhesive), a cured layer of resin (such as latex), or a hardened layer of a rubbery substance (such as a bituminous material) etc. By creating such a fused layer, the loops of the yarns are anchored to the primary backing and therewith adequately mechanically attached to withstand normal mechanical loads. In order to create the fused layer, the intermediate product with the starting material for the fused layer is normally transported through a long oven (50-100 meters), typically at 180-200° C. in order to create an adequate fused layer. EP 1598476 (Klieverik Heli) describes a method in which no latex or bituminous layer is used to anchor the yarns to the primary backing. The layer of molten material is created by feeding the backing (yarn upwards) along a heated roller surface while its underside is pressed against the roller so the yarns will at least partly melt to form a layer of fused material, the layer optionally incorporating an adhesive applied in the form of a powder before the back side of the primary backing is processed using the heated roller. In the application it is stated that after cooling the yarns are firmly anchored to each other and the backing without the need for a latex polymer. One embodiment teaches that pressure may be applied after heating (e.g. by a pressure roller) to the backing and piles in a direction perpendicular to the backing surface (i.e. from below) to smear the plasticised yarns together to enhance their mutual adhesion, thus allowing the heated roller to be held at a lower temperature, below that at which the yarns would actually directly fuse by heat alone. This method provides the advantage that the intermediate backing can be easily recycled since the yarns and primary backing can be made from the same polymer. There is no incompatible latex or bituminous material penetrated into the fibre piles.
WO 2012/076348 (Niaga) describes a method for manufacturing textile products that even improves the anchor strength of the yarn with respect to the method as described in EP 1598476. In this method, when the primary backing is pressed against the heated surface, a relative speed between the primary backing and the heated surface is introduced. Due to this relative speed, an additional mechanical force is provided on the molten material in the machine direction (i.e. the direction of transport of the primary backing). This force spreads the material of the yarn whilst it is still molten resulting in a more homogenous layer of fused material and thus a stronger overall bond between the primary backing and the yarns. Though in theory in many cases an additional secondary support layer may no longer be necessary, this document does teach that such a support layer may still be useful, especially if it comprises a reactive adhesive relying on thermally reversible reactions between reactive molecules present at the interface between the textile product and the carrier material.
A research disclosure (RD591084) was also published anonymously on 25 Jun. 2013 describing certain methods for manufacturing carpets using a method as described here above in combination with polyester hot melt glues.
For high end applications polyamide yarns are often used for the pile of textile products. Polyamide (PA or nylon) are very resistant to wear and abrasion, have good mechanical properties even at elevated temperatures, and have good chemical resistance. However, polyamide has a very low stain resistance whereas polyester (used for yarns in non-high end applications) generally has a good stain resistance.
It is an object of the invention to provide for a method to manufacture a textile product using polyamide yarns, wherein the polyamide yarns have an improved staining resistance.
In order to meet the object of the invention a method to manufacture a textile product as defined in the GENERAL FIELD OF THE INVENTION section has been devised, wherein during creating of the layer of fused material, at least the distal half of the length of the pile is maintained at a temperature at least 70° C. below the melting temperature of the polyamide.
Without being bound to theory, this invention was based on a couple of recognitions. First of all, it was recognised that in all polyamide yarns, the polyamide material is at least to some part amorphous. As is commonly known, the amorphous part of polyamide can be oriented or non-oriented (see for example Appl Spectrosc. 2005 July; 59(7):897-903). The number of amino and acid groups available for stains to attach to, is believed to be higher in the non-oriented amorphous zones. Heat setting generally increases the percentage of this stain sensitive non-oriented amorphous part. In the traditional manufacturing technologies, heat is used to create the fused layer, typically well above 180° C., whereby due to a heat flux to the yarns, even the distal (top) half part of the pile is heated to temperatures such that this heat setting typically occurs. This means that the pile yarns have a decreased resistance towards staining when compared with the starting yarn material. Applicants found that by keeping the temperature of at least the distal half of the length of the pile (when a pile has a mixed height, the distal half of the length of the highest pile is relevant) at a temperature of at least 70° C., preferably at least 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99° C. or more, below the melting temperature of the polyamide during a period wherein the layer of fused material is created, heat setting as described here above can be prevented or at least significantly reduced, such that at least this top half of the pile has a improved stain resistance when compared to traditionally made textile products, in particular carpet products such as broadloom carpet, carpet tiles, mats (such as entrance mats and car mats) and rugs.
The invention is also directed to the use of a textile product obtainable according to the invention to cover a surface of a building or any other artificial or natural construction. The invention is also directed to a device for use in manufacturing a textile product comprising a first sheet having polyamide yarns fastened to this sheet to form a pile thereon, the yarns being stitched through the sheet to form the pile on a first surface of the sheet, the pile extending for a predetermined length from this first surface, and loops of the yarns at a second surface of the sheet, wherein the device comprises respectively a heating means for heating the second surface of the sheet, a means for creating a mass of fused material on the second surface of the sheet, and cooling means for cooling at least the distal half of the length of the pile to a temperature at least 70° C., preferably at least 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99° C. or more, below the melting temperature of the polyamide during creating the mass of fused material.
The invention is also directed to a textile product comprising a sheet having a top surface and a bottom surface, the textile product having polyamide yarns stitched through this sheet to form a pile on the surface of the sheet, the pile extending for a predetermined length from this first surface, the yarns being fastened to the bottom surface of the sheet by forming a layer of fused polyamide material on this bottom surface, the yarns in the pile have a decreased amorphous content with respect to yarns of the same polyamide annealed at a temperature of about 43° C. (i.e. between 40 and 45° C.) below the melting temperature of the polyamide for 1 hour.
A textile product is a product that comprises textile (i.e. material made mainly of natural or artificial fibres, often referred to as thread or yarn), optionally with other components such as backing layers, carrier layers and/or adhesives. Laminated textile products typically comprise an upper layer of pile attached to a backing (where the raised pile fibres are also denoted as the “nap” of the product), but may also be flat weave. Such products can be of various different constructions such as woven, needle felt, knotted, tufted and/or embroidered, though tufted products are the most common type. The pile may be cut (as in a plush carpet) or form loops (as in a Berber carpet).
Polyamide yarns are yarns containing at least 10% of polyamide material, preferably at least 20, 30, 40, 50, 60, 70, 80, 85, 90, 95 up to 100% of polyamide.
Polyamide (PA or nylon) is the generic name for all long-chain fiber-forming polyamides with recurring amide groups. Depending on the type of PA, melting temperatures may range from 190 to 350° C., typically between 220 and 260° for polyamides used for making yarns for textile materials such as carpet (mainly PA6 and PA66). PA is always at least partly amorphous (either completely amorphous or semi-crystalline). PA6 (nylon 6), also called polycaprolactam, is a polymer developed by Paul Schlack to reproduce the properties of PA66 (nylon 6,6). Like PA66, it is a semicrystalline polyamide. Unlike most other nylons, PA6 is not a condensation polymer, but instead is formed by ring-opening polymerization. It's melting temperature is around 220° C.
A loop of a yarn is a length of this yarn that may be curved away from the basic part of the yarn (not excluding that the loop is longer than the main part itself). For a textile product, the basic part of the yarn is the part that forms the upper, visible part of the product. For example, for a carpet this is the part of the yarns that forms the pile. For clothing, this is the part of the yarn that forms part of the outer surface of the clothing. The loop is the part that extends from the back surface of the product.
A sheet is a substantially two dimensional mass or material, i.e. broad and thin, typically, but not necessarily, rectangular in form, and inherently has two opposite surfaces.
Stitching is a method of mechanically making a yarn part of an object by stitches or as if with stitches, such as by tufting, knitting, sewing, weaving etc.
A layer is a thickness of material, laid on or spread over a surface. A layer may be inhomogeneous with respect to thickness and may be discontinuous in the sense that it may have holes in it.
A laminate is a structure comprising multiple stacked layers mechanically connected to each other.
Resilient means to be able to deform and automatically return to the original configuration.
A hot melt adhesive is a thermoplastic adhesive that is designed to be melted, i.e. heated to transform from a solid state into a liquid state to adhere materials after solidification. Hot melt adhesives are typically non-reactive, crystalline and comprise low or no amount of solvents so curing and drying are typically not necessary in order to provide adequate adhesion.
Fibrous means consisting basically out of fibres. The term “basically” in this respect means that the basic mechanical constitution is arranged out of fibres: the fibres may however be impregnated or otherwise treated or combined with a non-fibrous material such that the end material also comprises other constituents than fibres. Typical fibrous sheets are woven and non-woven textile products, or combinations thereof.
In a first embodiment of the method according to the invention the distal half of the length of the pile is maintained at a temperature at least 100° C. below the melting temperature of the polyamide. It was found that although 70° C. is already well below the melting temperature, and thus, heat setting was expected to be not or hardly present, the method could be improved by maintaining the temperature of the yarns at least 100° C. below the melting temperature of the polyamide. Apparently, heat setting still occurs to some relevant extent even in the range of 70-100 degrees celsius below the melting temperature of the polyamide. It is found that the heat setting can be prevented substantially completely when the temperature is maintained at 125-150° C. below the melting temperature of the polyamide.
In a second embodiment the at least distal half of the length of the pile is maintained at the temperature below the melting temperature of the polyamide using cooling means. Such cooling means may for example be a chilled roller contacted with the pile side of the first sheet, or a blower for blowing cold gas over this pile side, while the back of the sheet is heated in order to form the fused layer. However, any other passive or active means for maintaining the temperature of the pile at a temperature as defined according to the invention may be used instead.
In another embodiment, for fastening the yarns to the sheet, the second surface of the sheet is contacted with a surface of a hot body to at least partly melt the loops of the yarns to create the mass of fused material. In this embodiment the layer of fused layer to anchor the yarns is created using methods as known for example from EP 1598476 and WO 2012/076348. To applicant's surprise, even when using such a method wherein a hot surface is used to actually melt the polyamide in the loops of the yarns, the temperature of the pile (at least the distal half of the pile) can be kept below a temperature where heat setting significantly influences the stain resistance of the polyamide. This can be done using either active cooling means, or depending mainly on the height of the pile, the density of pile, the exact materials used, and the required time of contact with heated surface to create the layer of fused material, by simply relying on the heat transport through the pile (by conduction, radiation and/or convection) being too slow to heat up the top half of pile above the critical temperature regarding inducing a staining problem.
In a further embodiment the surface of the hot body has a relative speed (and thus moves at a relative speed greater than 0 m/s) with respect to the second surface of the first sheet. As such, the use of a hot body that has a relative speed with respect to the second surface during the melting process of the yarns is known from WO 2012/076348. It now appears that this feature is ideally suitable for use in a method wherein the yarns are polyamide yarns, aiming at an increased stain resistance of the pile. In a further embodiment the surface of the hot body is stationary, whereas the first sheet is transported along the hot body.
In an embodiment wherein the textile product is a laminate of the first sheet and a second sheet, after the second surface of the first sheet has been processed according to any of the embodiments as described supra, an adhesive is applied to this second surface to which adhesive the second sheet is adhered. In a further embodiment the adhesive is a hot melt adhesive, for example a hot melt adhesive that comprises at least 50% by weight of a polymer chosen from the group consisting of polyurethane, polycarbonate, polyester, polyamide, poly(ester-amide), polyolefine, mixtures thereof and/or copolymers thereof.
In a further embodiment of the laminated textile product, an intermediate layer is provided between the first sheet and the second sheet wherein the intermediate layer is resilient to allow local deformation of this layer along the second surface of the first sheet or along the surface of the second sheet adjacent to the intermediate layer. This embodiment appears to be suitable to prevent or at least mitigate a common problem of laminated textile products: internal strain in the laminate, in particular due to the influence of moist, temperature or other environmental variables. Internal strain on its turn may lead to various problems. With carpet tiles for example, internal strain may lead to the problem of curl: the edges or corners of the tiles tend to curl up. Curling of edges or corners is a problem since the edges in general to not coincide with an edge of the surface to be covered, and thus, the curled up edges or corners may lead to irregularities in center areas of the covered surface. With broadloom carpet, internal strain may lead to deformation such that interstices are formed at the joint of two sections of carpet. Also, for any laminated textile product, internal strain may lead to bulges and local excessive wear. An important reason for the occurrence of internal strain is that the laminate inherently comprises different layers (note: the term “layer” or “sheet” does not exclude that the layer or sheet is actually constituted out different sub-layers) that need to provide very different properties to the textile product: the first sheet (the primary backing) needs to stably bear the pile yarns. The second sheet (the secondary backing) in general provides dimensional stability to the textile product. For this reason, the structure of the different layers is inherently different. And thus, even when for example the first and second sheet are made of the same material, the occurrence of internal strain due to different deformations by the action of moist and temperature, is inherently present. The problem is even increased when different materials are being used for constituting the sheets, in particular when these materials per se expand and contract differently due to moist and or temperature. In the present invention, the pile yarns are polyamide yarns, whereas the polymer used for the primary and secondary backing is mostly polyester. These polymers have totally different deformation characteristics due to moist and temperature. It has now been surprisingly found that this problem can be solved or at least mitigated when using a resilient layer as described here above in between the first and second sheet. Without being bound to theory, it is believed that due to the resilient properties as defined here above, it is provided that each of the sheets may expand or contract (“deform”) in the horizontal direction independently of an expansion or contraction of the other sheet, and thus, that no (or only low) internal strain (which may lead to curl or other deformation) may arise. This can be understood as follows: due to the resiliency of the intermediate layer which allows local deformation of the material in this layer along the surface of at least one sheet, the horizontal deformation of (one of) the sheet(s) may now be locally absorbed by the intermediate layer, without mechanical forces being transferred directly from the first sheet to the second sheet or vice versa.
In yet another embodiment the intermediate layer is a fibrous layer. Fibres can be easily assembled to form a stable layer, and still provide for the option of local deformation. For example when fibres are entangled but not mechanically connected at the sites were fibres cross, deformation may stay locally, while the layer as a whole has significant mechanical stability.
In still another embodiment the intermediate layer is a non woven layer. Non woven layers are easy to assemble, even when using very short fibres and are therefore economically attractive. While short fibres may prevent deformation to be easy transferred over distances considerably longer than the fibres themselves, long fibres, due to the non-woven arrangement (for example meandering like a river) may also be perfectly capable of allowing local deformation and not transferring forces to the neighbouring areas.
In a further embodiment the intermediate layer is a knitted layer. A knitted layer, although the fibres are in essence endless, appears to be perfectly suitable to allow only local deformation. Like a tubular knitted sock that fits every curve of a foot, a knitted layer can easily deform locally without transferring forces to neighboring areas. A knitted layer for use in the present invention is for example Caliweb®, obtainable from TWE, Emsdetten, Germany.
Example 1 provides process parameters for a method according to the invention
Example 2 is an example of a specific laminated textile product according to the invention
Example 3 provides a method to establish dirt retaining properties of carpet.
Example 4 provides a method to determine whether or not the textile product is a product according to the invention.
The (intermediate) textile product to be processed with the above described configuration (the product itself is not shown in
Downstream of the heating blocks, at both sides of the transport path 200 of the intermediate textile product to be processed, is a further active cooling means 300. In this embodiment, the means 300 comprise inverted domes 301 and 302. Through these domes, cold cooling air can be blown towards the textile product, in order to actively cool the heated surface of the textile product.
The hot melt adhesive may be optionally provided as a layer having a thickness of less than 1 mm, usefully less than 0.5 mm, more usefully from 0.2 to 0.4 mm. Whereas in the prior art carpets on the market, the hot melt layer typically has a thickness well above 1 mm, applicant found that when reducing the thickness of this layer to 1 mm or below an adequate adhesion can still be obtained. Therefore, the adhesive layer present in textile products of the present invention may have preferred mean thickness of from 50 microns to 1 mm, more preferably from 0.1 mm to 0.8 mm, most preferably from 0.2 mm to 0.4 mm. The amount of HMA used to form the adhesive layer in textile products of the present invention may be from 0.01 to 1000 g/m2 of HMA per area of the adhesive layer. In another embodiment the HMA may be applied in an amount of from 0.05 to 800 g/m2. In a still yet other embodiment HMA may be applied in an amount from 0.1 to 600 g/m2.
Example 1 provides process parameters for a method according to the invention. In this example, the process parameters for a set up as depicted in
Example 2 is an example of a specific laminated textile product according to the invention. Reference numbers refer to parts corresponding to the textile product as shown in
A piece of carpet made in accordance with example 2 was tested regarding its properties to retain dirt (or, to let go dirt). In this method a piece of carpet having dimensions of 180×600 mm is firstly intensively contacted with dirt, by adding 15 grams of so called “VNTF” dirt (a standard type of dirt, a predetermined mixture of pigmented organic and inorganic solid materials, mineral oil, and quartz crystal sand, standardized by the Organisation of Dutch Carpet Producers; available from the TFI Institute in Aachen, Germany), and fixing the dirt in a Tetrapod machine (see Journal of the Textile Institute Transactions, Volume 56, Issue 3, 1965) during 800 rotations. After this, the carpet is cleaned in a standardised way using a machine as described in EP2198263 (titled “A method for testing the impact of a cleaning process on a property of a fabric, an apparatus for use in such a method, and use of said method or apparatus for labelling a fabric”), in particular with reference to
From this experiment it can be concluded that a PA carpet made according to the invention has better dirt release properties than traditional carpet and therefore can be qualified as a low stain carpet.
Example 4 provides a method to determine whether or not the textile product is a product according to the invention. In this method the polyamide material which is the same as the material used for the yarns in the textile product is subjected to an annealing temperature well below 180° C. This temperature is chosen since it is a typical temperature for any conventional backing oven used to fuse a secondary backing to a textile material and is about 43° C. below the melting temperature of a typical PA used for making carpet. The fact that the amorphous content of the material after 1 hour of annealing is below that of the same material annealed at 180° C., demonstrates that such a material processed according to the method of the invention will also lead to a product according to the invention.
Depicted in Table 2 are the results from the annealing experiment of PA6 material typically used for yarns of carpet products. The material is presented as non-fiber bonded fibers, and heated for 1 h at different temperatures as indicated. The lowest temperature is about 150° C. below the melting temperature of the polyamide. The middle-temperature is slightly over 70° C. below the melting temperature. With a differential scanning calorimeter device, the Tg (glass transition temperature) and Tm (melting temperature) of the material is measured after the heat treatment.
The measurements show that at 180° C. (about 43° C. below the melting temperature of the polyamide used), the Tg and Tm drop and thus that fibers are more amorphous, in line with theory. This means that the fibers, by staying at least 70° C. below the melting temperature of the polyamide, remain higher in crystallinity.
| Number | Date | Country | Kind |
|---|---|---|---|
| 15193216.7 | Nov 2015 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2016/076683 | 11/4/2016 | WO | 00 |
