GENERAL FIELD OF THE INVENTION

The present invention pertains to a method for manufacturing a carpet product, which method typically comprising providing a sheet having a front surface and a back surface as a primary backing, and one or more yarns stitched through this first sheet to form a pile on the front surface of this primary backing. At the back surface, the one or more yarns are locked to the primary backing, typically by applying a latex or other adhesive. In particular, the invention pertains to a method that leads to a carpet product that is suitable for commercial use, i.e. a product of class 31 (Moderate Commercial Use), 32 General Commercial Use) or 33 (Heavy Commercial Use) according to the European norm EN 1307:2014 + A3:2019 (including the Vetterman test according to ISO 10361 :2015). The invention also pertains to a carpet product that is obtainable with a manufacturing method according to the invention.

BACKGROUND OF THE INVENTION

In the present-day world carpeting is used for multiple purposes. An important reason for using carpet products is esthetics. Other purposes are (walking) comfort, noise attenuation and hygiene. Considerations to take into account when making a carpet product for a specific purpose however also include the weight of the carpet product, the cost of the product, the feel (or the “hand”) of the product and importantly, durability. High end carpet products are typically tufted constructions. Tufted carpet products generally include a composite structure in which tufts, or bundles of carpet fibers are introduced (such as by stitching) into a primary backing, such as a woven or non-woven fabric. These carpet fibers are typically a yarn consisting of nylon, polyester, wool or polypropylene, with nylon being the most common. A secondary backing or coating of thermoplastic material is then commonly applied to the underside of the carpet construction in order to securely retain the tufted material in the primary backing. This secondary backing not only dimensionally stabilises the carpet product but may also provide greater abrasion and wear resistance, and may serve as a basis for adhering an additional layer of material. Tufted nylon carpet has superior wear characteristics and as a result is generally preferred in commercial applications (such as e.g. in stores, hotels, conference centers, restaurants, offices, cars, air terminals, trains, aircraft, elevators and entrance areas) versus the less superior wear of polyester carpet products. Nylon however has some drawbacks. Apart from being relatively expensive, it is not easy to recycle (it needs chemical recycling) and is more sensitive for staining. Also, dimensional stability is not optimal. In that respect, polyester, in particular polyethylene terephthalate (PET) seems a better alternative, being relatively inexpensive, easy to recycle, with a natural stain resistance and potentially a better dimensional stability. However, the wear resistance of carpet made with polyester yarns is too low to arrive at a product suitable for commercial use. Polyester based carpet is thus mainly used for domestic applications.

In the art, several attempts have been made to arrive at a carpet product using polyester yarns, which product has an improved durability. For Example., US 2020/0190718 (assigned to Invista North America S.A.R.L, Wilmington, USA) discloses a carpet with self-twisted loop piles that has an appearance and esthetics similar to a cut pile carpet products but with improved durability. For this the carpet product comprises a single yarn (a so-called 1 -ply yarn) twisted at a higher twist level than typically used which is stitched through a preconstructed woven or nonwoven fabric backing to form a loop or a tuft. Due to the high twist level the loop pile gets automatically twisted. It is described that the 1 -ply yarn is twisted in the range of 1 to 15 turns per inch (tpi), which equals 40-600 tpm (turns per meter), in particular 200-400 tpm. The single yarn is directly tufted into carpet without a yarn heat setting step. Although the PET carpet passes the Vetterman test to arrive at a high quality carpet product in this respect, a disadvantage of the high twisting level is that the tuft bind strength is relatively low such that overall durability is still below what is needed for (high end) commercial use. Also, the self-twisted 1 -ply yarns provide an appearance that is not appreciated in all markets.

WO96/35836 (assigned to 3M, Saint Paul, USA) describes a carpet product that is capable of withstanding significant pedestrian traffic and is useful for placement at the entryway of a building, for example, to wipe wet and/or dirty shoe soles. It is described that polyester yarns can be used to manufacture the carpet product. The product comprises a pile layer of tufted bundles of textured synthetic resinous filaments, each filament having a linear density of at least 800 denier, the filaments in each tufted bundle arranged in loops of random shapes and orientations and intermingled with loops in adjacent tufted bundles of filaments in the pile layer. The pile layer has a thickness when measured outward from the surface of the substrate of at least 5 mm and preferably between 5 mm and 15 mm. This way, a heavy carpet product is produced that has the ability to retain soil and which is resilient and durable enough to withstand pedestrian traffic without significant deterioration. This makes the product very suitable for an outdoor mat or rug. However, the high pile prevents that the product maintains its initial esthetic appearance and thus is not suitable for high end indoor applications.

CN 10228619 discloses a colored glossy and elastic fine denier carpet and manufacturing method high end domestic use. The carpet uses yarns having a relatively high weight (DTex above 2400), and a twist level of about 50-130 tpm. The combination of a high weight yarn and a high twist level provides good appearance and resilience. However, durability is too low to meet the requirements for commercial applications.

US 2008/0220200 (assigned to Futuris Automotive Interiors Inc., Troy, USA) discloses a PET carpet product that is suitable as a carpeting for the interior of cars. For this a tufted PET carpet product is described comprising a pile of PET yarn comprised of PET fibers and tufted at a pre-determined gauge into a first backing layer, the pile layer having a particular face weight, a back coating layer of an adhesive adjacent the first backing and an underlayment layer adjacent the second backing layer. The backing adhesive is applied using an extrusion process to lock the tufted PET to the backing, and steam is applied to the tufted PET to enhance the look and feel of the PET. This leads to a product suitable for use in cars. However, the method is rather complicated making the product relatively expensive.

US 2016/0136844 (assigned to Milliken & Company, Spartanburg, USA) discloses a 100% polyester fully recyclable carpet, using a very high viscosity polyester adhesive to securely bond the tuft yarns. However, fuzz-resistance is still relatively low (Velcro rolling fuzzing resistance of 2 or less). At higher fuzzing resistance (4) there is no adhesive left to bond a secondary backing. This makes the carpet less attractive for high end uses. OBJECT OF THE INVENTION

It is object of the invention to provide an improved method to manufacture a carpet product that is easy to recycle yet is suitable for commercial use, in particular meeting at least class 31 of European norm EN 1307:2014 + A3:2019, preferably class 32 or 33. It is another object to provide such a carpet product.

SUMMARY OF THE INVENTION

In order to meet the object of the invention, a method to manufacture a carpet product is devised, the method comprising providing a first sheet having a front surface and a back surface (which sheet is commonly denoted as the primary backing), providing one or more polyester yarns having a weight of at least 2500 Dtex (such as for example at least 2500, 2550, 2600, 2650, 2700, 2750, 2800, 2850, 2900, 2950, 3000, 3050, 3100, 3150, 3200, 3250, 3300, 3350, 3400, 3450, 3500, 3550, 3600, 3650, 3700, 3750, 3800,

3850, 3900, 3950, 4000, 4100, 4200, 4300, 4400, 4500, 4600, 47004800, 4900, 5000,

5100, 5200, 5300, 5400, 5500, 5600, 5700, 5800, 5900, 6000, 6100, 6200, 6300, 6400,

6500, 6600, 6700, 6800, 6900, at least 7000 or even above) and a twist level of at least

100 tpm (such as for example at least 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 220, 230, 240, 250, 260, 270, 280, 290, at least 300 or even above), forming a pile on the front surface of first sheet by stitching the one or more yarns through the first sheet, the one or more yarns having a free end that forms the said pile and a locked end present at the back surface of the first sheet, thereby forming an intermediate product, processing the intermediate product by feeding this product along a body having a heated surface, the back surface being contacted with the said heated surface, to melt at least a part of the polyester of the locked end of the one or more yarns, and cooling the molten part of the polyester to solidify this molten part of the polyester, thereby connecting the locked end of the one or more yarns to the first sheet and forming the carpet product.

Polyester yarns are inherently easy to recycle, as is commonly known in the art.

Mechanical recycling is an option, as is one of the many known processes for chemical recycling such as those used for recycling polyester bottles (e.g. as disclosed in WO 2022/003084, assigned to Cure Technology BV). The durability requirements for meeting commercial standards are surprisingly met by combining a relatively high weight (also denoted as “count” or “titer”) of the polyester yarns (above 2500 Dtex), with a relatively high twist level (above 100 tpm) and a method to connect the yarns at the back of the primary backing by melting instead of using a coating such as latex. Such a method for connecting polymer yarns to a primary backing per se is known in the art, i.a. from WO 2012/076348 (assigned to Niaga BV), but not in combination with the other features to arrive at a product that meets the requirements for high end commercial use. It appears that when combining these three technical features (particular Dtex level, twist level, and binding the yarns by melting) when using polyester yarns, the object of the invention can be met, in particular, one is able to provide a carpet product that meets at least class 31 of European norm EN 1307:2014 + A3:2019, and even class 32 or 33 depending on the (other) characteristics of the carpet product.

Although it is not completely clear why the combination of these features provides the desired effect for a carpet product using polyester yarns, it is believed that the high twist level at least partly compensates for the lack of inherent resilience of the polyester yarns. The relatively high Dtex value on its turn appears to be able to compensate for the loss of fluffiness due to the high twist level. Importantly, it was applicant who recognised that typically a high twist level is disadvantageous for arriving at a proper filament binding level. This may be due to the fact that adhesives can penetrate less efficient into the yarns. However, the melting and colling down feature for bonding the yarns at the back as used in the present manufacturing method does not have this disadvantage. On the contrary, the higher the density of the yarns, the better the heat conduction and thus melting process may take place.

Although it was found that meeting the Dtex and tpm value as recited here above enables the provision of a carpet product suitable for (high) end commercial use, it is particularly preferred that the tpm level (at a Dtex value above 2500) meets the following relation with the value for the wight of the yarns: 100 (formula 1) If the tpm level is indeed above the value according to this formula (60000/(Dtex-2500) + 100), combinations of a relatively low tpm and low Dtex value (within the invention) can be avoided such that there is more freedom for other characteristics of the carpet product such as gauge (distance between needles per inch), stitch rate (number of stitches per inch in the length of a carpet product), pile height, number of filaments in the yarns, ply of the yarns, dpf etc.

In line with the method as described here above, the invention also pertains to a carpet product comprising a first sheet having a front surface and a back surface and one or more polyester yarns stitched through the first sheet, forming a pile on the front surface of the sheet, which yarns have a weight of at least 2500 Dtex and a twist level of at least 100 tpm, wherein at least a part of the polyester of the locked end of the one or more yarns is molten, spread over the back surface of the sheet and solidified.

DEFINITIONS

A yarn is a unitary textile wire or thread that can be used in a stitching process. Typically, a yarn consists of a bundle of twisted strands of fibres, which fibres on their turn consist of a bundle of entangled filaments.

A multiply yarn is a yarn that is composed of multiple strands that are twisted together as one yarn. Three-ply yarn for example, is composed of three single strands that are twisted together.

A polyester product is a product that consist at least for more than 50 mass % out of a polyester polymer, preferably at east 55, 60, 65, 70, 75, 80, 81 , 82, 83, 84, 85, 86, 87, 88, 89I 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 up to 100 mass%.

A polyester is a category of polymers that contain the ester functional group in every repeat unit of their main chain (Kbpnick H, Schmidt M, Drugging W, Ruter J, Kaminsky W (June 2000). "Polyesters". Ullmann's Encyclopedia of Industrial Chemistry.

Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA.). Examples of polyester are Polycaprolactone (PCL), Polylactic acid (PLA), Polyhydroxybutyrate (PHB), Polyglycolic acid (PGA), Polyethylene adipate (PEA), Polyethylene terephthalate (PET; such as Mylar®, Rynite® and Impet®), Polybutylene terephthalate (PBT; such as Crastin® and Celanex®,), Polyethylene naphthalate (PEN), Polytrimethylene terephthalate (PTT; such as Sorona®), Polyester of 4-hydroxybenzoic acid and 6- hydroxynaphthalene-2-carboxylic acid (LCP), Polyester of Bisphenol A and phthalic acid (PAR).

Dtex (or dtex) is the mass (weight) of a (single) yarn in gram per 10,000 m. In the art this is also denoted as (total) yarn count or titer and is the total mass of a final yarn after twisting.

Dpf is denier per filament, wherein denier is the weight in grams of 9,000 meters of an individual filament.

A twist level of a yarn is the total number of twists as present per meter of yarn, i.e. the number of bumps in a yarn per meter divided by the ply number (Berka, Amanda (Winter 2007), "Technically Speaking: Twists Per Inch", SpinOff Magazine, Interweave, pp. 11-12).

A carpet product is a relatively thick textile product used for covering a floor or another object which is tread upon such as the interior of a car. Typical carpet products are broadloom carpet, carpet tiles, mats and rugs

A sheet is a substantially two dimensional mass or material, i.e. a broad and thin, typically, but not necessarily, rectangular in form.

Fibrous means consisting basically out of fibres. “Basically" 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.

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 felted layer is a layer of non-woven separate fibres which are matted together using mechanical impact, optionally using heat and moist.

A hot melt adhesive is a thermoplastic adhesive that is designed to be melted, i.e. heated to undergo a first order transition to transform from a solid state into a liquid state to adhere materials after solidification. Hot melt adhesives are typically non- reactive, (at least partly) crystalline and comprise a low amount of or no solvents (0-5 m%, preferably 0-2 m% or even 0-1 m%) so curing and drying are typically not necessary in order to provide adequate adhesion.

Intrinsic viscosity is a measure of a solute's contribution to the viscosity q of a solution, see “Progress in Biophysics and Molecular Biology" (Harding 1997). The IV can be measured according to DIN/ISO 1628. Typically, a concentration of 1% for the polymer is used and m-cresol as solvent, wherein the IV can be expressed in dl/g (often presented without the latter dimension). A practical method for the determination of intrinsic viscosity is by using an Ubbelohde viscometer.

EMBODIMENTS OF THE INVENTION

In a first embodiment of the method according to the invention the one or more polyester yarns have a weight of at least 2800 Dtex and a twist level of at least 120 tpm. At this level of Dtex and tpm, in combination with the melting step of the yarns at the back, even improved durability properties can be obtained, enabling the manufacturing of a carpet product that meets class 32 and 33 (according to European norm EN 1307:2014 + A3:2019). Although it was found that meeting these Dtex and tpm values enables the provision of a carpet product suitable for high end commercial use, it has been found that it is particularly preferred that the tpm level (at a Dtex value above 2800) meets the following relation with the value for the wight of the yarns:

30000

TPM (jBDtex > 2800) > - -I- 120

Dtex — 2800 (formula 2) If the tpm level is indeed above the value according to this formula, combinations of a relatively low tpm and low Dtex value (within the above embodiment) can be avoided such that there is more freedom for other characteristics of the carpet product such as gauge, stitch rate, pile height, number of filaments in the yarns, ply of the yarns, dpf etc.

In a second embodiment of the method according to the invention the one or more polyester yarns have a weight of at least 3000 Dtex and a twist level of at least 150 tpm. At this level of Dtex and tpm, in combination with the melting step of the yarns at the back, even further improved durability properties can be obtained, enabling the manufacturing of a carpet product that even meets class 33 (according to European norm EN 1307:2014 + A3:2019).

In yet a next embodiment of the method according to the invention the first sheet is a polyester sheet. This has the advantage that the product is even more easy to recycle since the yarns and the sheet do not need to be separated for recycling and can be processed as one, for example by shredding and thereafter melting the shredded product, optionally followed by a chemical process.

In yet another embodiment the polyester comprises PET (polyethylene terephtalate) and/or PTT (polytrimethylene terephthalate). These types of polyester, either alone or in combination were found to be particularly suitable for manufacturing a carpet product. PET has the advantage that it is readily available as recycled material at a low price and still is able to meet high quality standards enabling the use for producing hight quality yarns for textile applications, even high end carpet applications. For this it is preferred that the polyester has an intrinsic viscosity above 0.8 dl/g (which is typical for a bottle grade product of PET). The higher the iv, the better the polymer is used for producing high quality yarns and thus high end carpet products. Moreover, it is advantageous that in the carpet product only one type of polyester is used for both the yarns and the sheet, and optionally other polymer containing parts of the product.

In again another embodiment of the method according to the invention, the one or more yarns are multi-ply yarns, in particular 2, 3 or 4 ply. It was found that with a multiply yarn it is easier to apply higher twist levels and thus to arrive at a higher class of durability in the present invention. A single ply yarn at a high twist level (typically above 120) becomes self-twisting which is disadvantageous for many applications. In yet again another embodiment of the method according to the invention, the one or more yarns are each composed of multiple filaments having a weight of between 2 and 40 dpf. This low dpf value may lead to a more comfortable hand, while at the same time still being able to meet the desired durability requirements. This probably has to do with the higher flexibility of the filaments. Preferably, the filament weight is between 5 and 20 dpf, even more preferably between 8 and 12 dpf such as 8, 9, 10, 11 or 12 dpf.

In still another embodiment of the method according to the invention, the one or more polyester yarns have a weight of at least 3500 Dtex, preferably at least 4000 Dtex. It was found that at this weight the durability could be further increased. For nylon carpet product such weight are hardly applied due to the cost of goods.

In yet another embodiment of the method according to the invention, the step of processing the intermediate product by feeding this product along a body having a heated surface, the intermediate product has a relative speed (not being zero) with respect to the heated surface of the body. In this embodiment the molten fraction of the yarns is spread in a direction parallel to the surfaces of the first sheet by imparting a mechanical force on the molten fraction in the said direction. This mechanical force may lead to a calendaring process, virtually uniting the (molten) yarn ends at the back of the intermediate product into one continuous and smooth layer of material. This improves the tuft bind and hence the durability properties of the resulting carpet product.

In another embodiment of the method according to the invention, the method comprises connecting a second sheet to the carpet product, using an adhesive applied between the processed back surface of the first sheet and the second sheet. By applying a second sheet, commonly referred to as the secondary backing, the dimensional stability of the product can be improved, as well as the (walking) comfort and/or the ease of laying the product.

Preferably, the adhesive is a hot melt adhesive. A hot melt adhesive, due to its crystalline properties, is relatively brittle when cold. As such, it was expected that the local deformation of the intermediate product would lead to breakage of the adhesive and hence delamination. This does not appear to be the case. In a further embodiment the hot melt adhesive is a polyester adhesive. This is advantageous for the recycling of the carpet product which already comprises polyester yarns. In another embodiment of the method according to the invention, the second sheet is a fibrous sheet, preferably a felted sheet. Most preferably the second sheet is a polyester sheet.

It is noted that any of the above features of the embodiments of the method according to the invention, correspond to embodiments of the resulting carpet product.

The invention will now be explained in more detail using the following non limiting examples that disclose particular embodiments of the invention and comparative examples.

EXAMPLES

Figure 1 schematically shows a cross section of a prior art textile product.

Figure 2 schematically shows details of the product of figure 1.

Figure 3 schematically shows a configuration for applying a fibre-binding process.

Figure 4 schematically shows a laminating configuration.

Figure 5 schematically shows a cross section of a textile product according to the invention.

Example 1 describes various carpet products according to the invention.

Example 2 describes various comparative examples.

Example 3 provides several methods for recycling a carpet product according to the invention.

Figure 1

Figure 1 schematically shows a cross section of a carpet product in line with the invention, in this case a carpet tile class 33. The tile comprises a first sheet 2, the so called primary backing, Propex Artis True™, a woven PET sheet obtained from Propex Fabric GmbH, Gronau, Germany, with a cap (see figure 5) of 30 g/m ² PET yarns. Trilobe PET yarns 5 with a dpf of 30, obtained from Pataga, Peer, Belgium are tufted into this primary backing at a gauge of 1/10” and stitch rate of 42. Before tufting the yarns are plied to obtain a 2-ply yarn, twisted to a level of 200 tpm, after the which the yarns are heat set to maintain the twists. By plying and twisting the basic yarns this way, the resulting yarns have a Dtex value of 3600. After tufting and cutting, the yarns 5 extend with their end 7 through this backing and form loops over its back surface 4. This way the ends 7 are locked into the primary backing 2. The free ends 6 of yarns 5 extend from the first surface 3 of the sheet to form a pile thereon. The yarns 5 are mechanically durably connected to the primary backing by sealing the locked ends 7 to the second surface 4 of the sheet using the fibre binding method as described with reference to figure 3. In order to provide mechanical stability, the carpet tile 1 comprises a second sheet 8, in this case a backing of a polyester needle felt backing fleece obtained from VEBE Floor Coverings Genemuiden. The weight of this second sheet is about 900 g/m ² . Optionally, in between the first and second sheet is a further backing layer 10, for example a polyester expansion fleece having a weight of 330 g/m2, which can be obtained from TWE as Abstandsvliesstof, a non-woven fabric which has not been needle-punched. Both sides of this layer 10 are constructed of a mesh of 100% PET which has been mechanically solidified. The thickness of this intermediate layer is about 4 mm. The backings are adhered together using a polyester hot melt adhesive from Covestro, Leverkusen, Germany, applied as layers 11 and 12 at a weight of about 300 g/m2. The total weight of the resulting carpet tile (without the optional backing layer 10) is about 2.2 kg/m ² .

Figure 2

Figure 2 schematically shows details of the product of figure 1 at various stages of manufacturing. Figure 2 depicts the intermediate product 100, which consists of the primary backing 2 and yarns 5 tufted therein. As depicted, the locked ends 7 of the yarns 5 form loops at the back surface 4 of the primary backing. The free ends 6 extend from the front surface 3 of the primary backing. The yarns 5 can in theory be easily removed from this intermediate product since the yarns are simply stitched into this backing. By applying a light pulling force by hand for example, each of the yarns can be easily removed from the primary backing. In order to durably connect the yarns to the primary backing a fibre-binding process is applied as known from WO 2012/076348, further elaborated upon in detail with reference to figure 3. In this process the back of the intermediate product 100 is dragged along a heated body in contact therewith, in order to at least partly melt the loops of the yarns and possibly also some of the material of the primary backing at its back surface, and at the same time to make the back surface smooth by forcing the molten material to spread a little bit over the back surface 4 of the primary backing. This results in a flat and smooth layer wherein at least part of the material of the locked ends 7, as far as originally present in the loops and being molten, is more or less spread into a flat configuration onto the back surface 4 of the primary backing. The processed intermediate product 100’ is depicted in figure 2B. It was found out that despite the melting and spreading action, yarns may still get pulled out of the processed product (and thus, out of the final textile product) when pulling forces are used that correspond to pulling forces exerted during (very) high load use of the textile product, depending on the type of yarn, yarn material, type of primary backing, its material etc. Without being bound to theory, it is believed that this may be due to a tension build up at the positions 51 and 52 where the yarns come out of the primary backing. High tension build up may lead to breakage and hence, a free end of the yarn that is no longer tightly secured at the back of the primary backing. If indeed the tuft bind strength is below 20-25 N, it is often needed to apply a secondary backing which inherently increases the tuft bind strength.

Figure 3

Figure 3 schematically shows a configuration for applying a fibre-binding process, in this case a process derived from the basic process as known from WO 2012/076348. In the configuration shown in Figure 3a first heating block 500 and a second heating block 501 are present, in order to heat the heating elements, also denoted as heating blades or heating bodies, 505 and 506 respectively. These heating elements have a working surface 515 and 516 respectively, which surfaces are brought in contact with an intermediate product 100 to be processed, typically a primary backing to which yarns are applied via a stitching process such as tufting. The working surfaces both have a working width of 18 mm, and the intermediate distance is 26 mm. The back surface of the product is brought in contact with the working surfaces of the heating elements. In order to be able and apply adequate pressure for the product to be processed, a Teflon support 520 is present which is used to counteract a pushing force applied to the heating elements. In operation, the heating elements are moved relatively to the product in the indicated direction X. Typically, the heating elements are stationary, and the intermediate product 100 product is forced to travel between the working surfaces and the Teflon support in a direction opposite to the direction indicated with X. The product 100 to be processed with the above-described configuration consists of a first sheet (primary backing) provided with a cut pile of polyester yarns, tufted into the sheet. The yarns typically have a melting temperature of about 255-265°C. This product is processed using a temperature of the first heating element of 200-220°C, in order to pre-heat the product. The second heating element is kept at a temperature about 15- 20°C above the melting temperature of the yarns. To keep the temperatures at the required level, the heating blocks and heating elements are provided with layers of insulating material 510, 511, 512 and 513 respectively. The product is supplied at a speed of 12 mm per second (0.72 metre per minute) or higher, and the pressure applied with the heating elements is about 1.35 Newton per square centimetre. After this, the product is cooled down to past the solidification temperature of the molten polyester (which for a pure crystalline polyester is equal to the crystallisation temperature) to solidify this molten part of the polyester, thereby forming an anchor for the yarns and thus connecting the locked end of the yarns to the primary backing. This results in a product 100’ having a calandered back surface, i.e. being smooth and glossy at the sites where the stitched yarns extend from the back surface.

Figure 4

Figure 4 schematically shows a laminating configuration for applying a second sheet, in this case a dimensionally stable secondary backing sheet to the back of the first sheet that is produced with a method as described in conjunction with Figure 3. In this figure a first roller 600 is depicted on to which roller is wound a 2 metre wide web of the processed intermediate product 100’ made according to the method described in conjunction with Figure 3. The product is unwound from the roller 600 to have its backside 217 to come into contact with a second roller 601. This roller is provided to apply a layer of polyester hot melt adhesive (HMA) 219 to the back side 217. For this, a bulk amount of the HMA 219 is present and heated between the rollers 601 and 602. The thickness of this layer can be adjusted by adjusting the gap between these two rollers. Downstream of the site of HMA application is the secondary backing 215, which backing is unwound from roller 603. This secondary backing is pressed against the hot and tacky adhesive and cooled in the unit 700. This unit consists of two belts 701 and 702 which on the one hand press the secondary backing 215 against the primary product 100’, and on the other hand cools down the adhesive to below its solidification temperature. The resulting end product 201 is thereafter wound on roller 604. In an alternative embodiment the fibre-binding process as described in relation with Figure 3 and the lamination process take place in line. In that case, the fibre-binding set-up as shown in Figure 3 could be placed between roller 600 and roller 601. In that case, intermediate product 100 is wound of the roller 600 and fed along the rest of the process steps. Figure 5

Figure 5 schematically shows a cross section of an intermediate carpet product for use according to the invention. This figure corresponds to figure 1 , but displays the cap layer 20 of the primary backing 2’ in detail. In figure 5A a first sheet 2 is depicted having a front surface 3 and a back surface 4. The back surface 4 of this Propex woven PET sheet 2 is covered with a porous layer 20, in this case a felted fibrous layer of short PET yarns. This layer is made by covering the back surface of the sheet 2 with 5 Dtex fibres having a length of about 50 mm. The fibres are provided in amount of about 30 g/m ² . This layer is needle-felted to the first sheet, thereby forming a new dual layer primary backing 2’ (corresponding to element 2 in figure 1). The needle felting process is stopped when a final thickness (for the porous layer) of about 2 mm is reached. The resulting porosity in this layer is about 98%.

As depicted in figure 5A the yarns 5are tufted into the primary backing 2’ such that the locked ends 7 form loops that run over the back surface 4’ of the porous layer 20 (which in effect is the back surface of the complete primary backing 2’), thereby forming intermediate product 110. This product is subjected to the fibre-binding process as described with reference to figure 3. The result of this is schematically depicted in figure 5B. The porous layer has partly melted, together with a part of the locked ends 7 of the yarn 5, and forms a thin layer 20’ of partly molten and compressed fleece, having the ends of the yarns securely locked therein. This layer can best be compared to glassfibre strengthened resin: a more or less continuous layer, provided with entangled fibres, including the ends of the yarns in its mass. This way, the yarns 5 in the processed intermediate product 110’, appear to be even better bonded to the primary backing when compared with the bonding as obtained without the porous layer.

Example 1

Example 1 describes various carpet products according to the invention. The yarns used are all PET yarns, plied, twisted and heat set after twisting (as commonly done in the art to more or less secure the twists). The primary backings are in each case woven PET backings, obtained from firms as indicated in Table 1. The primary backings all have a cap as described with reference to figure 5. Carpet products 1 to 4 use a cap of 50 g/m ² , whereas for numbers 5 to 10 the cap has a weight of 30 g/m ² . The yarns are all fibre bonded using a method corresponding to the method described with reference to figure 3. For the products 1 to 4 a melting temperature of 295°C was used. For products 5 to 9 a temperature of 270°C was used, whereas for product 10 this temperature was 275°C. The products all use a secondary felted PET backing as indicated in the table. This backing is adhered with polyester hot melt adhesive (see WO 2014/198731 and WO 2014/198732). The indicated Dtex value is the total Dtex of the plied yarns used for stitching. The used primary backings are all woven PET products, obtained from either Mattex, Harelbeke, Belgium or Propex Fabric GmbH, Gronau, Germany. The secondary backings are all needle felted PET products. The TWE backings are obtained from TWE Vliesstoffwerke GmbH & Co Emsdetten (500 g/m ² for products 1 and 3, 900 g/m ² for products 2 and 4). The VeBe backinsg are obtained from VEBE Floor Coverings Genemuiden (all 900 g/m ² ). The yarns are all PET yarns. Pharr yarns are obtained from is Pharr McAdenville, USA. Pataga yarns are obtained from Pataga, Peer, Belgium and the Beekaylon yarns are obtained from Beekaylon, Mumbia, India.

The resulting carpet products were all subjected to a classification test according to European standard EN1307:2014+A3:2019, including the commonly known Vetterman test. This test may lead to a qualification as follows:

Domestic use

Class 21 : Moderate Domestic Use

Class 22: General Domestic Use

Class 23: Heavy Domestic Use

Commercial Use

Class 31 : Moderate Commercial Use

Class 32: General Commercial Use

Class 33: Heavy Commercial Use

The products of the invention all met the classification for Commercial use, even reaching class 32 and 33 for some products, in particular at a combination of a Dtex of 3000 or higher and a twist level of 144 or higher. As is commonly known, the gauge and stitch rate have hardly any influence on the obtained class, in particular when typical rates are applied such as 5/32” to 1/12”, such as for example the common 1/8” and 1/10”, for the gauge and between 10 and 70, such as for example the common 30-60, in particular 38-44, for the stitch rate. The stitch rate tested was chosen because this fits best with the used fibre binding technology. A higher stitch rate also typically is beneficial for the Vetterman test results.

Table 1 Carpet products of the invention

Table 1 continued Carpet products of the invention Example 2

In this example various comparative examples are described and depicted in Table 2.

Table 2 Comparative examples

The materials used for the comparative examples are the same as used for the examples according to the invention and also, the fibre-binding process has been applied the correspondingly. The differences are due to differences in Dtex of the stitched yarns, in combination with a lower twist rate (at a level in line with common nylon carpet tiles to reach commercial class 31, 32 and 33). As can be seen, this leads to lower classification.

Example 3

In this example, apart from re-using the yarns as such (by cutting and making a new carpet product with the yarns), several methods are described for fully recycling a carpet product according to the invention. None of these methods requires separation of the carpet product into various polymer containing materials since all carpet products according to Table 1 (and also those of Table 2) are pure PET products in the sense that all polymer material used in the products (yarns, primary backing, secondary backing, adhesive) is polyethylene terephthalate. This provides various relatively easy options for recycling the products for circular use (as opposed to process such as pyrolysis, decarbonisation and using the PET as an additive in for example stone mastic asphalt, cementitious materials, mortars or concrete composites etc.).

The methods all include primary steps wherein the carpet product is firstly cut into smaller pieces that enable easy uptake in recycling methods.

A first example of a class of processes that allows circular use of the polyester are processes based on (thermo-) mechanical methods to recycle polyester waste material. The simplest way of thermo-mechanical recycling is re-melting the polyester waste. This method is applied for example in bottle-to-bottle technologies, where sorted PET-bottles are re-melted in crushed shape and reprocessed to bottles as beverage packaging.

A second class of processes to recycle polyester waste are the so-called chemical recycling (chemolysis) processes, wherein recycling of polyester waste material is enabled by depolymerisation into monomers and/or oligomers. This class can be divided in numerous sub-classes depending on the type of reactant used for the chemolysis.

An example is the application of ionic liquids for de-polymerization, first described around the year 2000. This method was developed to avoid the drawbacks of other methods like alcoholysis (high pressure and temperature as well as a heterogeneous reaction product) or acidic and alkaline hydrolysis (pollution problems) to provide an eco-friendly degrading agent for polymers and to enable degradation under moderate reaction conditions.

As an alternative castor oil is applied for de-polymerisation. This method was developed to provide a renewable substitute of petrochemical agents (for example, glycols) for PET de-polymerization. After de-polymerization, the reaction products were aimed for the preparation of polyurethane systems.

The degradation of polyester polymers using enzymes was first described in the 1970’s. As the use of ionic liquids and castor oil, this bio-chemical method was developed to provide an eco-friendly procedure of polymer recycling in contrast to conventional chemical recycling methods. Alcoholysis for de-polymerization of PET was first described in the early 1990’s. This method was developed to avoid the drawbacks of the acidic and alkaline hydrolysis (pollution problems) to provide a renewable and more eco-friendly degrading agent for polymers. Generally, polyester is de-polymerised with an excess of an alcohol to yield corresponding esters of the corresponding acid and ethylene glycol. Among the alcoholysis methods, reaction with methanol has gained special importance because of the low price and the availability of methanol. Also ethylene glycol (a diol, the use of which is sometimes classed separately as “glycolysis”, although it falls in the class of alcoholysis) is used mainly in reactive extrusion to produce low molecular weight oligomers. However, these oligomers have to be separated and purified for further processing, since the crude reaction product consists of a heterogeneous mixture of monomer, oligomers and polymers. Various other alcohols are described to be useful such as pentaerythritol, 1-butanol, 1-pentanol and 1-hexanol and 2-ethyl-1 - hexanol. Also other diols than ethylene glycol, like BHET, neopentyl glycol (NPG), tetraethylene glycol (TEEG), polyethyleneglycol, polytetramethylene oxide and terpoly[poly(oxyethylene)-poly-(oxypropylene)-poly(oxyethyle ne) are described in the art for depolymerizing polyester by alcoholysis. An improved method of alcoholysis has been described in recent patent application W02022/003084 (assigned to Cure Technology BV) in which method in a first stage of two consecutive stages, a stream of polyester waste material is continuously fed to an extruder operated at a temperature above the melting temperature of the polyester, while alcohol is fed to the extruder, and in a second stage, the fluid mixture is continuously fed to a continuously stirred tank reactor (CSTR) operated at a temperature above the melting temperature of the polyester, while co-feeding a second amount of alcohol to the CSTR, to provide at the outlet of the CSTR a continuous stream of polyester depolymerised into an oligomeric ester. The oligomers can be used to make new polyester of any quality.

Aminolysis and ammonolyis were developed for polyester recycling, since the reactivity of the amine-group is higher than the hydroxyl-group or alcohols used alcoholysis of polyester.

Lastly, an alternative chemical recycling of polyester is given by the controlled depolymerization of polyester using blocking chain scission with defined amounts of the de-polymerization agent (see Geyer et al. in eXPRESS Polymer Letters Vol.10, No.7 (2016) 559-586). This method produces polyester oligomers of well-defined molecular weights in a greater range than existing chemical methods like alcoholysis.