EP1964956B1 - Highly stable light carpet backing and method for its production - Google Patents

Abstract

The fleece comprises a layer of melt-spun synthetic filaments consolidated by high-energy water jets. The novel feature is a small quantity of thermally-activated binder. This is applied as a thin layer on the fleece layer. The fleece is constructed as a three-layer system. The central layer is low-melting thermoplastic polymer binder and the two outer layers are synthetic filaments. The melting temperature of the polymer is preferably at least 20[deg] C below that of the synthetic filaments. The titer of the synthetic filaments is preferably 1.0-4.0 dtex. The fibers are polyester, especially polyethylene terephthalate and/or a polyolefin, especially polypropylene. The low-melting polymer is largely polyethylene, a copolymer with a significant proportion of polyethylene, a copolyester, a polyamide and/or a copolyamide. The low-melting polymer fraction is less than 7 wt%, preferably 1.5-5 wt% with respect to the total weight of backing. The low-melting polymer comprises spun or melt-blown fibers or fibrils. Two-component fibers are used, the low-melting component being the thermally-activated binder. In manufacture, the fleece is laid by a fleece-spinning process. The thin layer of binder is applied. Water-jetting is then followed by drying and thermal activation of the binder. Water-jetting is controlled to achieve a specific longitudinal strength of 4.3 N/5cm per g/m 2>. The specific initial longitudinal modulus at 5% extension is at least 0.45 g/5cm per g/m 2>. The fibers or fibrils are deposited by air-laying or melt-blowing. An independent claim is included for the corresponding method of manufacture.

Description

Technical area

The invention relates to a high-strength lightweight tufted carrier made of spunbonded nonwoven, which comprises at least one layer of melt-spun synthetic filaments, which are solidified by means of high-energy water jets.

State of the art

From the DE PS 17 60 811 is a tufted support based on a spunbonded polypropylene. The filaments forming this tuft carrier have a coarse titer greater than 10 dtex and are segmentally stretched in a particular manner such that stretched longer segments of high crystallinity in the same thread follow less stretched, less crystalline segments with a slightly lower melt temperature. These serve in the composite as a binding component, which is activated in the subsequent thermal solidification with direct steam. According to the petition, the length of the well stretched crystalline segment is about 11 inches and the length of the subsequent less stretched and less crystalline segment is about 1 inch. The proportion by weight of the low-crystalline segments is therefore slightly more than 8%. The special nonwoven structure, which has such a tufting support is rather unimportant for this consideration.

From the DE PS 22 40 437 and DE PS 24 48 299 is a tufted support based on a polyester spunbonded fabric known. Also according to these patents coarse threads are used for the production of the tufting carrier, namely matrix threads of polyethylene terephthalate with a titer of more than 10 dtex. According to the references, simultaneously with the polyethylene terephthalate matrix threads, binder threads having a lower denier and consisting of a low-melting copolyester are spun. The proportion by weight of these binding threads is about 20%.

According to the teachings of the patents listed above, a tufting support should be constructed so that in the system of matrix threads and bonds the bonds between the threads are always weaker than the threads bound by them. In the following tufting process, in which a large number of needles penetrates the carrier and sews the pile yarn into it, the bonds between the threads are primarily broken without it comes to thread breakages. The threads can avoid the penetrating needles and form a "collar" around the tufted pile yarn. Thus, the strength and the tear resistance of the tufted raw carpet are maintained at a high level, there is hardly any damage caused by the tufting process.

In the known thermally bonded systems, it has been found that the bonds usually have a very high strength and that a targeted influence on the bond strength is very difficult. To adjust the ratio between bond strength and thread strength described above thus only an increase in the thread strength by using coarser threads remains. Consequently, titres of more than 10 dtex are proposed in the above documents for the matrix threads. An essential Disadvantage of such coarse threads, however, is that in order to achieve sufficient tufting for strength and coverage, high basis weights on the order of at least 100 to 120 g / m ^{2 are} required.

To overcome this disadvantage, is in the DE PS 198 21 848 C2 , which forms the generic prior art, proposed to produce a tufted from a spunbonded synthetic filaments without binder, wherein the spunbond is to be solidified only by the action of high-energy water jets. The entanglement of the filaments by water jets produces a multitude of very weak bonds. Any such interfacial friction-only bond per se is very weak - certainly weaker than the filaments so intertwined. Consequently, the bonds can be loosened up without the filaments being damaged or even broken, as a result of which the mobility of the filaments in the tufting process is readily ensured. There is no significant damage to the filament structure during tufting. On the other hand, however, the very high number of weak bonds adds up to such an extent that the nonwoven material thus solidified achieves a very high absolute strength overall. A major advantage of this system is that finer filaments can be used in the construction of the nonwoven fabric. Titers from 0.7 to 6 dtex are specified in the patent. This makes it possible to produce spunbonded fabrics with lower basis weights, which both have sufficient strengths and appear to be closed enough to be used as tufting carriers.

A disadvantage of the above tufting is that it does not lose strength by the Tuftprozess, but that the initial modulus of the raw carpet is low and therefore is not sufficiently dimensionally stable in the subsequent processing steps.

Due to the hardly avoidable stresses occurring during the refining steps, in particular a longitudinal distortion and, associated therewith, a width jump of the raw carpet can occur. To prevent this, appropriate precautionary measures, such. As a voltage control to be taken.

Presentation of the invention

The object of the invention is to develop a tufting support of the generic type so that it has sufficient strength for further processing and thus dimensional stability even after tufting, without the known good behavior during tufting is impaired.

This object is achieved with a tufting support having all the features of patent claim 1. A method for producing a tufting carrier according to the invention is described in claim 11, a preferred use of the invention is described in claim 15. Preferred embodiments of the invention are described in the subclaims.

According to the invention, in a high-strength lightweight spunbonded tufted carrier comprising at least one layer of melt-spun synthetic filaments solidified by high-energy water jets, it is provided that it contains a small amount of a thermally activatable binder which is in the form of at least one thin layer is applied to the layer of melt spun filaments.

Without wishing to restrict the invention to this, it is assumed that the tufting process can lead to an excessive loosening of the weak bonds in the carrier. As a result, the initial module of the raw carpet is obviously lowered so much that the raw carpet is not sufficiently dimensionally stable during further processing. It comes to the described delay of the raw carpet.

It has now surprisingly been found that by applying at least one thin layer of a binder to the layer of melt-spun synthetic filaments in combination with the subsequent hydroentanglement, drying and activation of the binder - in addition to the water jet bonds - further bonds ( or bonding points) between the spunbond filaments, which are still weak enough not to interfere with the mobility of the spunbonded filaments during tufting. The still remaining after tufting high number of fine bonded together by the above-mentioned additional binding points spunbond filaments contribute to the carpet has high modulus and sufficient for further processing dimensional stability. In the case of the tufting support according to the invention, no additional measures for dimensional stabilization, such as, for example, the tension control mentioned above, are necessary during further processing. It is believed that this effect u. a. This is also due to the fact that some of the binder is carried by the high-energy water jets even into the deeper layers of the Viiesstofflage into and forms binding points there.

An inventive tufting carrier can be constructed from one or else several layers of spunbonded fabric and binder. Other additional layers may also be provided, provided that they do not interfere with either the tufting process or the further processing.

In a preferred embodiment of the invention, the tufting carrier according to the invention has a 3-layer structure in which the middle layer comprises the binder and the outer layers comprise the melt-spun synthetic filaments. Since the hydroentanglement often takes place on both sides, this has the advantage that the binder is introduced into the nonwoven fabric layer both from the lower side and from the upper side.

Low-melting thermoplastic polymers are particularly suitable as binders, preference being given to those thermoplastic polymers whose melting temperature is sufficiently lower than that of the spun-bonded non-woven filaments. Preferably, the melting temperature should be at least 10 ° C, more preferably at least 20 ° C below the melting temperature of the spunbond filaments, so that they are not damaged during thermal activation.

The low-melting thermoplastic polymers preferably also have a broad softening range. This has the advantage that the thermoplastic polymer used as a binder can be activated even at lower temperatures than at its effective melting point. From the technological point of view, the binder does not necessarily have to be fully fused, but it is sufficient that it is sufficiently softened and thus adheres to the filaments to be bound. In this way, one can adjust the degree of bonding between the spunbond filaments and the binder in the activation phase.

The low melting thermoplastic polymer preferably consists essentially of polyethylene, a copolymer having a substantial proportion of polyethylene, polypropylene, a copolymer having a substantial proportion on polypropylene, a copolyester, a polyamide and / or a copolyamide.

The weight fraction of the low melting polymer relative to the total weight of the tuft carrier should not exceed 7%. If the proportion of Schmetzklebers is too high, so there is a risk that the spunbonded fabric is too strong thermally bonded. The bonds made by the hot melt adhesive would definitely be stronger than those by the bonded filaments. In the tufting process, the filaments would then be considerably damaged, torn and therefore the strength after tufting, especially the tear propagation resistance too much impaired.

The weight fraction is preferably between 1.5 and 5% by weight. At a weight fraction of less than 1.5 wt .-%, the reinforcing effect, especially from the point of view of the initial module, would not be sufficiently pronounced. In addition, due to the small amount, it would not be possible to achieve sufficiently good distribution of the binder in the spunbonded cross section through the water jet treatment. However, even the use of smaller proportions of hot melt adhesive is advantageous and is therefore intended to be embraced by this invention.

The low-melting polymer may be in the form of fibers or fibrils, for example. In particular, biko-fibers can be used as fibers, the low-melting component representing the thermally activatable binder.

The present invention enables the use of low denier filaments for the spunbonded filaments. Even with low basis weights this is a good strength and sufficient Cover achieved. Preferably, the fiber titer is between 0.7 and 6 dtex. Fibers with a denier between 1 and 4 dtex have the particular advantage that they provide good surface coverage at medium basis weights on one side, but that they themselves still have sufficient total strengths so as not to be damaged in the tufting process by the needle penetration, to be torn.

A tufting carrier according to the invention preferably comprises filaments of polyester, in particular polyethylene terephthalate, and / or of a polyolefin, in particular polypropylene. These materials are particularly suitable because they are made from bulk raw materials that are available everywhere in sufficient quantity and quality. Both polyester and polypropylene are well known in fiber and nonwoven fabric manufacture for their utility.

1. a) Ablegen von wenigstens einer Lage aus synthetischen Filamenten mittels eines Spinnvliesprozesses;
2. b) Aufbringen wenigstens einer dünnen Schicht aus einem thermisch aktivierbaren Bindemittel;
3. c) Verteilen des Bindemittels und Verfestigen der Spinnvliesfilamente mittels energiereicher Hochdruckwasserstrahlen;
4. d) Trocknen
5. e) Thermische Behandlung zum Aktivieren des Bindemittels;

A suitable method for producing a tufting carrier according to the invention comprises the method steps;

1. a) depositing at least one layer of synthetic filaments by means of a spunbonding process;
2. b) applying at least one thin layer of a thermally activatable binder;
3. c) distributing the binder and solidifying the spunbond filaments by means of high-pressure, high-pressure water jets;
4. d) drying
5. e) thermal treatment to activate the binder;

The production of spunbonded nonwovens, ie the spinning of synthetic filaments of various polymers, including polypropylene or polyester, as well as their storage to a random web on one Carrier prior art. Large-scale facilities with widths of 5 m and more can be purchased from several companies. You can have one or more spin systems (spin bars) and set to the desired performance. Hydroentangling systems are also state of the art. Even such systems can be supplied in large widths from several manufacturers. The same applies to dryers and winders.

The thermally activatable binder can be applied by various methods, e.g. B. by powder, even in the form of a dispersion. Preferably, however, the binder is applied in the form of fibers or fibrils by means of meltblown or airlaying. These methods are known and widely described in the literature.

Meltblown and airlaying processes have the particular advantage that they can be combined as desired with spinning systems for spunbonded filaments.

The hydroentanglement should, as from the DE 198 21 848 C2 known, preferably be carried out so that a specific longitudinal strength of at least 4.3 N / 5cm per g / m ^{2 of} the basis weight and a starting modulus measured in the longitudinal direction as a stress at 5% elongation of at least 0.45 N / 5cm per g / m ^{2 basis} weight can be achieved. This ensures a sufficient strength of the tufting carrier and a sufficiently good distribution of the binder in the spunbonded layer.

For the purposes of the invention, activation is to be understood as the generation of binding points by means of the binder, for example by melting or melting a low-melting polymer used as a binder. Both the drying and the thermal treatment for activation must be carried out at temperatures that are so low that Damage to the spunbond filaments, for example, by melting or melting is reliably avoided. For reasons of process economy, the drying and the thermal activation of the binder preferably take place in one process step. For drying and activation of the low-melting polymer, it is possible to use various types of dryer, such as tenter frames, belt dryers, or surface dryers, but a drum dryer is preferably suitable. The drying temperature should be adjusted in the final phase to about the melting temperature of the low-melting polymer and optimized depending on the results. Here, in particular, the entire melting behavior of the binder is taken into account. In the case of one which has a markedly wide softening range, it is not necessary to control the physical melting point. Rather, it is sufficient to seek the optimization of the binding effect already in the softening range. As a result, unpleasant marginal phenomena, such as the adhesion of the binding component to machine parts and Übervertestigung be avoided.

The tufting support according to the invention is suitable not only as a primary, but also as a secondary backing. Due to its very good mechanical properties, a tufting carrier according to the invention is also particularly suitable for producing a three-dimensionally deformable carpet, in particular for car interiors applications.

The invention will be explained in more detail below with reference to the exemplary embodiments:

Embodiment 1

The experimental plant for the production of spunbonded nonwovens had a width of 1200 mm. It consisted of a spinneret extending across the entire width of the plant, two blowing walls arranged opposite and parallel to the spinneret, a subsequent withdrawal nip extending in the lower area to a diffuser and forming a web formation chamber. The spun filaments formed a uniform fabric, a spunbonded fabric, on a collection tape sucked from below in the web formation region. This was compressed between two rolls and rolled up.

The preconsolidated spunbonded web was unrolled on a test rig for hydroentanglement. With the aid of an airlaying system, a thin layer of short binder fibers was applied to its surface, and the two-layer sheet was subsequently treated with a variety of high-energy water jets, thereby hydroentangled and solidified. At the same time, the binder was spread in the fabric. Thereafter, the consolidated nonwoven web was dried in a tumble dryer with the temperature in the end zone of the dryer set to activate the binder fibers and cause additional bonding.

In this experiment, a spunbonded nonwoven fabric was made of polypropylene. A spinneret was used which had 5479 spinning holes over the width mentioned above. The raw material used was polypropylene granules from Exxon Mobile (Achieve PP3155) with an MFI of 36. The spinning temperature was 272 ° C. The trigger gap had a width of 25 mm. The filament titer, measured according to the diameter in the spunbonded nonwoven, was 2.1 dtex. The production speed was set at 41 m / min. The resulting spunbonded fabric had a basis weight of 78 g / m ² . At the water consolidation unit, a 3 g / m ² layer of very short bicomponent fibers in sheath / core configuration, in which the core was polypropylene and the sheath was polyethylene, was first applied by air-flow web forming apparatus of the components was 50/50%. Thereafter, the spunbonded fabric was subjected to the water jet processing. The consolidation was carried out with the help of 6 beams, which alternately acted from both sides. The water pressure used was set as follows: Bar no. 1 2 3 4 5 6 Water pressure (bar) 20 50 50 50 150 150

In hydroentanglement, the short fibers were extensively drawn into the spunbonded fabric so that they did not form a pure surface layer.

Subsequently, the jetted spunbond fabric was dried in a tumble dryer. In the last zone, the air temperature was adjusted to 123 ° C, so that the polyethylene was easily fused and formed thermal bonds. The spun-bonded non-woven fabric thus consolidated had the following mechanical values at a basis weight of 80 g / m ² ; Maximum tensile force [N / 5cm] Maximum elongation [%] Strength at 5% Elongation [N / 5cm] Strength at 10% Elongation [N / 5cm] along 396 85 45 75 crosswise 70 105 4.5 9.8

The specific longitudinal strength was 4.95 N / 5 cm per g / m ² and the specific secant modulus at 5% elongation was 0.56 N / 5 cm per g / m ² .

The consolidated spunbonded fabric tufted well with common machine divisions. With a machine pitch of 1/64 inch resulted in tufted state the following mechanical values: Maximum tensile force [N / 5cm] Maximum tensile strain [N / 5cm] Tearing force [N] along 460 85 220 crosswise 110 100 ./.

Embodiment 2:

Polyester granules were used at the same experimental plant as described in Example 1. This had an intrinsic viscosity IV = 0.67. It was carefully dried so that the residual water content was below 0.01% and spun at a temperature of 285 ° C. In this case, as in Example 1, a spinneret with 5479 holes over a width of 1200 mm was used. The polymer throughput was 320 kg / h. The filaments had a visually observed titer of 2 dtex and a very low shrinkage in the spunbonded web. The line speed was set at 55 m / min so that the pre-consolidated spunbonded web had a basis weight of 80 g / m ² .

This was submitted to the same plant for hydroentanglement. A layer of 3 g / m ^{2 of the} same bicomponent short fibers (PP / PE 50/50) was placed on the surface of the preconsolidated spunbonded nonwoven. Then ran the Composite by water jet finishing with 6 bars set as follows; Bar no. 1 2 3 4 5 6 Water pressure (bar) 20 50 80 80 200 200

In hydroentanglement, the short binder fibers were largely incorporated into the spunbonded fabric so that they did not form a pure surface layer.

Subsequently, the jetted spunbond fabric was dried in a tumble dryer. In the last zone, the air temperature was adjusted to 123 ° C, so that the polyethylene was easily fused and formed thermal bonds. The spunbonded fabric thus consolidated had the following mechanical values at a weight per unit area of 82 g / m ² : Maximum tensile force [N / 5cm] Maximum elongation [%] Strength at 5% Elongation [N / 5cm] Strength at 10% Elongation [N / 5cm] along 395 88 48 80 crosswise 75 100 4.9 10.2

The specific longitudinal strength was 4.82 N / 5 cm per g / m ² and the specific secant modulus at 5% elongation was 0.59 N / 5 cm per g / m ² .

The consolidated spunbond fabric tufted well at various pitches. At a machine setting of 1/64 inch, the following mechanical values resulted in a tufted condition: Maximum tensile force [N / 5cm] Maximum tensile strain [N / 5cm] Tearing force [N] along 468 80 225 crosswise 120 95 ./.

In further operations, the behavior of the tufted carpet was called stable.

Claims (15)

1. High-strength lightweight tufting base composed of spunbonded web, more particularly for use as primary or secondary carpet backing, comprising at least one ply of melt-spun synthetic filaments consolidated by means of high-energy water jets, characterized in that it contains a small amount of a thermally activatable binder applied in the form of at least one thin layer onto the ply of melt-spun filaments.
2. High-strength lightweight tufting base according to Claim 1, characterized in that it is configured as a 3-ply system wherein the middle ply consists of binder and the two outer plies consist of synthetic filaments.
3. High-strength lightweight tufting base according to Claim 1 or 2, characterized in that the binder comprises a low-melting thermoplastic polymer.
4. High-strength lightweight tufting base according to Claim 3, characterized in that the low-meting thermoplastic polymer has a melting temperature at least 10°C, preferably at least 20°C below that of the synthetic filaments.
5. High-strength lightweight tufting base according to any one of Claims 1 to 4, characterized in that the synthetic filaments have a linear density of 0.7 to 6.0 dtex, preferably of 1.0 to 4.0 dtex.
6. High-strength lightweight tufting base according to any one of Claims 1 to 5, characterized in that the synthetic filaments comprise polyester, more particularly polyethylene terephthalate, and/or of a polyolefin, more particularly polypropylene.
7. High-strength lightweight tufting base according to at least one of Claims 1 to 6, characterized in that the low-melting polymer consists essentially of polyethylene, a copolymer having a substantial fraction of polyethylene, polypropylene, a copolymer having a substantial fraction of polypropylene, a copolyester, a polyamide and/or a copolyamide.
8. High-strength lightweight tufting base according to at least one of Claims 1 to 7, characterized in that the low-melting polymer comprises a weight fraction of less than 7%, preferably between 1.5 and 5%, based on the total weight of the tufting base.
9. High-strength lightweight tufting base according to at least one of Claims 1 to 8, characterized in that the low-melting polymer is present in the form of more particularly spun or melt-blown fibres or fibrils.
10. High-strength lightweight tufting base according to Claim 9, characterized in that the fibres are bicomponent fibres wherein the low-melting component represents the thermally activatable binder.
11. Process for producing a high-strength lightweight tufting base according to at least one of Claims 1 to 10, characterized by the following steps:

    a) laying down at least one ply of synthetic filaments by means of a spunbonded-web operation;

    b) applying at least one thin layer of a thermally activatable binder;

    c) consolidating the spunbonded-web filaments and distributing the binder by means of high-energy high-pressure water jets;

    d) drying

    e) thermal treatment to activate the binder.
12. Process according to Claim 11, characterized in that the drying and the thermal activation are effected in one process step.
13. Process according to Claim 11 or 12, characterized in that the water jet consolidation is controlled to achieve a specific longitudinal strength of at least 4.3 N/5 cm per g/m² basis weight and a specific initial modulus in the longitudinal direction measured as 5% elongation stress of at least 0.45 g/5 cm per g/m² basis weight.
14. Process according to at least one of Claims 11 to 13, characterized in that the fibres or fibrils are applied via an airlaying or meltblown process.
15. Use of a high-strength lightweight tufting base according to any one of Claims 1 to 10 in the manufacture of three-dimensionally formable carpets, more particularly for car interior applications.