EP2115201A2

EP2115201A2 - High-strength, light non-woven of spunbonded non-woven, method for the production and use thereof

Info

Publication number: EP2115201A2
Application number: EP08715677A
Authority: EP
Inventors: Ararad Emirze
Original assignee: Ruzek Ivo
Current assignee: Ruzek Ivo
Priority date: 2007-01-31
Filing date: 2008-01-31
Publication date: 2009-11-11
Anticipated expiration: 2028-01-31
Also published as: JP2010516918A; CN101641470A; WO2008092689A2; AU2008210021A1; AU2008209942B2; IN266809B; MX2009008049A; CA2676830C; TW200912072A; WO2008092689A3; DE502007004553D1; US20100104796A1; EP1964956B1; CN101636533B; RU2009132494A; CA2676824A1; CN101641470B; JP5384370B2; US20170002487A1; RU2415208C1

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

High-strength lightweight spun-bonded nonwoven fabric, process for its production and its use

The invention relates to a high-strength lightweight nonwoven fabric 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. Furthermore, the invention relates to a method for producing such a nonwoven fabric and its use.

The object of the invention is to provide a high-strength, lightweight nonwoven fabric made of spunbonded fabric, which is characterized not only by a high strength but also by a high initial modulus. A high initial modulus reduces the susceptibility to initial distortion and the resulting spread in the usual industrial processing steps.

This object is achieved with a nonwoven fabric spunbonded with all features of claim 1. A method for producing a spun-bonded nonwoven fabric according to the invention is described in claim 12, a preferred use of the invention is described in claim 16. Preferred embodiments of the invention are described in the subclaims.

BESTÄTBGUNGSKOPIE According to the invention, in a high-tenacity spunbond nonwoven fabric comprising at least one layer of melt-spun synthetic filaments solidified by high-energy water jets, it is provided that it contains a thermally activatable binder which is in the form of at least one thin layer made of melt-spun filaments.

When the threads are entangled by the high-energy water jets, a large number of very weak cohesive bonds form over the cross section of the nonwoven fabric. Each of these interfacial cohesive bonds is per se very weak, and in any case weaker than the strength of the connected threads. When a sufficiently high force is applied to such a consolidated spunbonded nonwoven fabric by an industrial processing step, the weak cohesive bonds produced by hydroentanglement are individually overloaded and loosened without damaging the constituent filaments. Only when the load is distributed to a sufficiently wide environment and all undamaged load-bearing threads are directed in the loading direction, the sum of the individual weak bond strengths comes into play and yet the nonwoven fabric has a high strength.

The initial compliance manifests on a force-strain diagram as a low initial modulus. In practical use arises under a corresponding load, a longitudinal distortion associated with a corresponding width entry. This complicates or sometimes even prevents the use of such spun-bonded spunbond web e.

An increase of the initial module thus appears as a priority technical task. It has 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. So there is a peculiar combination of a very high number of weak cohesive bonds with a much smaller number of far stronger adhesive bonds.

This high number of fine spunbond filaments bonded together by the above-mentioned additional bonding points contributes to the nonwoven fabric having high modulus values and dimensional stability which is sufficient for further processing. In the case of the nonwoven fabric according to the invention, no additional measures for dimensional stabilization, such as, for example, a tension control, are necessary during further processing. It is believed that this effect u. a. is also due to the fact that a part of the binder is carried by the high-energy water jets even into the deeper layers of the nonwoven layer into and forms binding points there.

A nonwoven fabric according to the invention may be composed of one or else several layers of spunbonded fabric and binder. It is also possible to provide other additional layers as far as they are meaningful for the respective application.

In particular, low-melting thermoplastic polymers are suitable as binders, preference being given to those thermoplastic polymers whose melting temperature is sufficiently lower than that of the spun-bonded nonwoven filaments is. Preferably, the melting temperature should be at least 10 ⁰ C, more preferably at least 20 ⁰ 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, that needs

Binders not necessarily 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 a polyolefin, in particular polyethylene, a copolymer comprising a substantial proportion of polyethylene, polypropylene, a copolymer comprising a substantial proportion of polypropylene, a copolyester, in particular polypropylene terephthalate and / or polybutylene terephthalate, of a polyamide and / or a copolyamide. When choosing the suitable low-melting polymer, the requirements of the later specific application should be taken into account.

The weight proportion of the low-melting polymer based on the total weight of the nonwoven fabric is preferably greater than or equal to 7%. If the proportion of hot melt adhesive is too low, the initial module gain will be too low and may not be sufficient for future use. The weight fraction is preferably between 9 and 15% by weight. When exceeding 15% by weight, the negative influence of the excessive number of strong adhesive bonds on the tear propagation resistance may possibly prevail.

However, even the use of smaller proportions of hot melt adhesive below 7% is particularly advantageous for certain applications and is therefore intended to be encompassed 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 being the thermally activatable binder.

The present invention enables the use of low denier filaments of spunbonded filaments. Even with low basis weights this good strength and sufficient coverage is achieved. Preferably, the fiber titer is between 0.7 and 6 dtex. Fibers with a titer between 1 and 4 dtex have the particular advantage that they ensure both good surface coverage at medium basis weights and have sufficient overall strengths.

A nonwoven fabric 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. In order to meet specific requirements of technical nonwovens, such as high initial modulus and / or stiffness and / or UV resistance and / or alkali resistance, it is possible to use as matrix fiber polymer in addition to PET (polyethylene terephthalate) also PEN (polyethylene naphthalate) and / or copolymers and / or or mixtures v. Insert PET and PEN.

Compared to PET, PEN is characterized by a higher melting point (about + 18 ° C) and a higher glass transition temperature (about + 45 ° C).

A suitable process for producing a nonwoven fabric according to the invention comprises the process steps:

a) depositing at least one layer of synthetic filaments by means of a spunbonding process; b) applying at least one thin layer of a thermally activatable binder; c) distributing the binder and solidifying the spunbond filaments by means of high-pressure, high-pressure water jets; d) drying 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 a carrier state of the 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 for hydroentanglement are also state of the art. Even such systems can be provided in large widths by several manufacturers. The same applies to dryers and winders. T

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 a meltblown or an airlaying process. 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 known from DE 198 21 848 C2, carried out so that a specific longitudinal strength of preferably 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. This ensures a sufficient strength of the spunbonded fabric 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 are to be carried out at temperatures which are so low that damage to the spunbonded 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, one can use various types of dryer, such as tenter frames, belt dryers, or Surface dryer, but preferably is a drum dryer. 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 over-consolidation, can be avoided.

Due to its very good strength and its high initial modulus, the nonwoven fabric according to the invention is suitable for applications in the technical field, in particular as a coating carrier, reinforcing or reinforcing material.

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 opposite and parallel to each other

Spinneret arranged blowing walls, a subsequent trigger gap, which expanded in the lower area to a diffuser and formed a web forming 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 distributed in the fabric. Subsequently, the consolidated nonwoven web was dried in a tumble dryer, with the temperature in the end zone of the dryer adjusted 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 46 m / min. The resulting spunbonded fabric had a basis weight of 70 g / m ² . At the water consolidation unit, a 16 g / m ² layer of very short bicomponent fibers in sheath / core configuration was first applied by means of an airlaid web forming apparatus, in which the core was polypropylene and the sheath was polyethylene. The weight ratio of the components was 50/50%. Thereafter, the spunbond was subjected to hydroentanglement. 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:

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 ⁰ C, so that the polyethylene was easily fused and formed thermal bonds. The spunbonded nonwoven thus consolidated had the following mechanical values at a basis weight of 86 g / m 2:

The specific longitudinal strength was 5.95 N / 5 cm per g / m 2 and the specific secant modulus at 5% elongation was 0.65 N / 5 cm per g / m 2.

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 61 m / min, so that the pre-consolidated spunbonded web had a basis weight of 72 g / m ² .

This was submitted to the same plant for hydroentanglement. A layer of 16 g / m ^{2 of the} same bicomponent short fibers (PP / PE 50/50) was placed on the surface of the preconsolidated spunbonded nonwoven. Thereafter, the composite passed through hydroentanglement with 6 bars set as follows:

In hydroentanglement, the short binder fibers were largely incorporated into the spunbonded fabric so that they did not form a clean 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 nonwoven thus consolidated had the following mechanical properties at a basis weight of 87 g / m 2:

The specific longitudinal strength was 6.09 N / 5 cm per g / m 2 and the specific secant modulus at 5% elongation was 0.68 N / 5 cm per g / m 2.

Claims

claims

1. High strength lightweight nonwoven fabric of spunbonded web, comprising at least one

Layer of melt-spun synthetic filaments, which are solidified by means of high-energy water jets, characterized in that it contains a thermally activatable binder, which is applied in the form of at least one thin layer on the layer of melt spun filaments.

2. High-strength lightweight nonwoven fabric according to claim 1, characterized in that the binder comprises a low-melting thermoplastic polymer.

3. High-strength lightweight nonwoven fabric according to claim 2, characterized in that the low-melting thermoplastic polymer a

Melting temperature which is at least 10 ⁰ C, preferably at least 20 ⁰ C below that of the synthetic filaments.

4. High-strength light nonwoven fabric according to one of claims 1 to 3, characterized in that the synthetic filaments have a titer of 0.7 to 6.0 dtex, preferably from 1, 0 to 4.0 dtex.

5. High-strength lightweight nonwoven fabric according to one of claims 1 to 4, characterized in that the synthetic filaments of polyester, in particular polyethylene terephthalate (PET), and / or from

Polyethylene naphthalate (PEN) and / or copolymers and / or mixtures of PET and PEN and / or of a polyolefin, in particular polypropylene.

6. High-strength light nonwoven fabric according to at least one of claims 1 to 5, characterized in that the low-melting polymer consists essentially of a polyolefin, in particular a polyethylene, a copolymer having a substantial proportion of polyethylene, polypropylene, a copolymer having a substantial proportion

Polypropylene consists of a copolyester, in particular a Polypropylenenterephtalat and / or a Polybutylenterephtalat, a polyamide and / or a copolyamide.

7. High-strength lightweight nonwoven fabric according to at least one of claims 1 to 6, characterized in that the low-melting polymer occupies a weight fraction of greater than or equal to 7%, preferably between 9 and 15%, based on the total weight of the nonwoven fabric.

8. High-strength lightweight nonwoven fabric according to at least one of claims 1 to 7, characterized in that the low-melting polymer is present in the form of uniformly scattered powder.

9. High-strength lightweight nonwoven fabric according to at least one of claims 1 to 7, characterized in that the low-melting polymer in

In particular spun or meltblown fibers or fibrils.

10. High-strength lightweight nonwoven fabric according to claim 9, characterized in that the melt-blown fibers or fibrils are deposited with air to form a uniform layer.

11. High-strength lightweight tufting support according to claim 9 or 10, characterized in that the fibers are bicomponent fibers, wherein the low-melting component represents the thermally activatable binder.

12. A process for producing a high-strength lightweight nonwoven fabric according to at least one of claims 1 to 11, characterized by the following steps:

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

13. The method according to claim 13, characterized in that the drying and the thermal activation take place in one process step.

14. The method of claim 11 or 12, characterized in that the hydroentanglement is adjusted so that a specific strength of at least 4.3 N / 5cm per g / m ² basis weight and a specific initial modulus measured in the longitudinal direction as stress at 5% elongation of at least 0.45 g / 5 cm per g / m ² basis weight.

15. The method according to at least one of claims 11 to 13, characterized in that the fibers or fibrils are applied using an airlaying or meltblown process.

16. Use of a high-strength lightweight lightweight nonwoven fabric according to one of claims 1 to 11 for industrial coatings, in particular for the construction industry as a reinforcing nonwoven fabric and for roof underlays, as well as for printed textile large advertising space.