EP2185757B1 - Method for producing a textile fabric consisting of at least partially split yarns, fibers or filaments - Google Patents

Abstract

The invention relates to a simple and economical method for producing textile fabric consisting of at least partially split yarns, fibres or filaments, in which, in particular, time consuming, energy and/or cost intensive processes are avoided. As a result, a dividable, initial textile fabric is divided or split at least partially into elementary filaments by treatment, in particular bombardment with dry ice, frozen water or an air-particle mixture at a temperature of at least 20 °C to 30 °C below the glass transition temperature (Tg) of the polymers used as yarns, fibres or filaments.

Description

The present invention relates to a process for producing a sheet from at least partially split yarns, fibers or filaments and to an apparatus for producing the same.

From the document EP 0 814 188 B1 is the preparation of a readily splittable nonwoven fabric of bicomponent filaments of the incompatible starting materials polyethylene terephthalate and polyamide 6 known. The nonwoven fabric is thereby exposed to the action of liquid pressure jets for separating the composite elements into elementary filaments and to their entanglement and bonding.

A process for the preparation of polymeric products, which are subjected to fine particles, is out EP0291026 known.

A method for treating the surface of textiles by subjecting to drying ice is out WO 01/36733 known.

A process for producing a sheet of at least partially split yarns, fibers or filaments is made EP 1428919 known.

The object of the present invention has been made to provide a method which simplifies the production process of fabrics of splittable yarns, fibers or filaments and is economically particularly favorable.

For the production process of fabrics of at least partially splittable yarns, fibers or filaments only one, for example, compared to a high pressure water jet treatment, especially in Pressing about 120 to 500 bar, particularly low energy or low mechanical force are needed.

Furthermore, in the method additional particularly time, energy, and / or cost-intensive process steps, such as the drying of the fabric required in a water jet treatment, should not be required.

Furthermore, the method is intended to enable at least partial splitting of both compatible polymers and conjugated yarns, fibers or filaments consisting of mutually incompatible polymers.

The solution of the objects is achieved with the features of claims 1 to 7.

With regard to the method according to the invention, a splittable starting sheet is formed by treatment, in particular by bombardment, with dry ice, with frozen water or with an air-particle mixture at a temperature of at least 20 ° C. to 30 ° C. below the glass transition temperature (Tg). the polymers used as game, fibers or filaments at least partially split or split into the elementary filaments.

The glass transition temperature (Tg) or softening temperature of an amorphous polymer used is the temperature at which the polymer exhibits the greatest change in deformability. The so-called Glass transition separates the below-lying brittle energy-elastic area (glass area) from the soft entropy-elastic area (rubber-elastic area) above. The transition to the flow region of the amorphous polymer is fluid. Semicrystalline polymers have both a glass transition temperature, below which the amorphous phase "freezes" (accompanied by embrittlement), as well as a melting temperature at which the crystalline phase dissolves. The melting temperature clearly separates the entropy-elastic range from the flow range.

Particularly suitable solid particles of the air-particle mixture are inorganic particles, such as sand (for example quartz sand), or polymeric granules.

Preferably, the dry ice, the frozen water or the air-particle mixture is used in the form of pellets. With respect to dry ice or frozen water, use as snow is also possible.

As dry ice pellets preferably cylindrical particles with a diameter of about 3 mm and a length between 5 and 30 mm are used here. In contrast, dry-ice snow is understood to mean finer-grained and therefore less hard particles which, for example, have a diameter of approximately 0.1 mm and a length of equal to or less than 1 mm.

The dry ice is frozen carbon dioxide with a temperature of about -78.5 ° C, which passes without residue into the gaseous state on impact with the splittable starting fabric (sublimation).

The use of dry ice therefore has the advantage that no subsequent separation or filtration, as for example when using an air-sand mixture, must be made of the split elementary filaments.

Furthermore, when using dry ice under normal pressure no liquid is formed, as for example in the case of water ice, whereby the term dry ice has also arisen.

Due to the fact that in the process according to the invention with the dry ice, the frozen water or the air-particle mixture no liquid, in particular no liquid water, is used for the splitting, an otherwise, for example in the case of a water jet treatment, required especially time, energy is eliminated -, and / or costly drying process of the fabric of at least partially split yarns, fibers or filaments.

By bombarding with dry ice, the temperature of the treated surface drops below the selected process parameters by about 60 ° C.

When using an air-particle mixture or frozen water, the treatment temperature is chosen such that the temperature of the treated surface is at least 20 to 30 ° C below the glass transition temperature (Tg) of the polymers used as game, fibers or filaments.

The fact that the treatment temperature is at least 20 to 30 ° C below the glass transition temperature (Tg) of polymers used as game, fibers or filaments, a certain embrittlement of the polymers is achieved, whereby the splitting of the fabric into elementary filaments is at least supported or promoted, without damage the elementary filaments.

Damage to the elementary filaments is also avoided by the comparatively low hardness of the dry ice, the air-sand mixture or the frozen water.

The use in the form of snow instead of pellets is particularly preferred in view of its smaller particle size or its low hardness (greater "softness") with regard to a filaments not particularly damaging, particularly gentle splitting or splitting.

Due to the sublimation effect of the dry ice in the treatment of the splittable starting fabric, the volume of carbon dioxide from the solid to the gaseous state of aggregation expands abruptly by about 600 to 800 times its original volume. The dry ice settles between the elementary filaments, whereby the splitting of the fabric into elementary filaments is also at least supported or promoted.

As an arrangement of the elementary filaments considered over the cross section of the game, fibers or filaments considered, for example, a core-shell structure (core-sheat structure) or an orange-slit or cake-piece structure (pie-structure) into consideration. It is particularly preferred to use as the splittable starting sheet one in which the elementary filaments are present in a pie structure, preferably having 2 to 64 segments, in particular for influencing the diameter of the filaments.

Preferred embodiments of the invention are the subject of the dependent claims.

Advantageously, a nonwoven fabric is used as the splittable starting sheet. As the nonwoven fabric, staple fiber nonwoven fabrics or spunbonded nonwoven fabrics having continuous fibers or composite fibers which are obtained by either a melt spinning or a solvent spinning process are preferably used.

Preference is given to using melt-spun nonwovens which have the advantage over solvent-spun nonwovens that no solvent has to be removed and that their use is less expensive.

As a splittable starting sheet is preferably a pre-bonded nonwoven fabric used, which is thermally, mechanically and / or chemically preconsolidated, particularly preferably thermally preconsolidated.

The yarns, fibers or filaments of the fabric preferably have at least two elementary filaments which are selected from polymer pairs or blends of polyolefins, polyesters, polyamides and / or polyurethanes in any desired combination with one another.

As preferred polyolefins, for example, polyethylene or polypropylene are used, as preferred polyesters, for example, polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, recycled polyester, polylactate or copolyester, as preferred polyamides, for example polyamide 6, polyamide 12, polyamide 66 or copolyamides.

For a good efficiency, the treatment, in particular the bombardment, takes place on the surface of the splittable starting sheet with the dry ice, the frozen water or the air-particle mixture preferably at an angle of incidence of 0.1 ° to 180 °, more preferably of 45 ° to 135 ° and most preferably of 90 °.

The kinetic energy of the particles of the dry ice, the frozen water or the air-particle mixture is advantageously equal to or more than 0.4 Joule. The mass and the speed of the particles are chosen so that there is no optical damage to the fabric or formation of a hole in the fabric.

The flow rate on the dry ice, on the frozen water or on the air-particle mixture is advantageously 30 kg / h to 70 kg / h, preferably 30 kg / h to 50 kg / h.

The particles of the dry ice, of the frozen water or of the air-particle mixture preferably impinge on the surface of the splittable starting fabric with an average size of 10 μm to 30 mm, particularly preferably of 0.1 mm to 10 mm.

The bombardment of the surface of the splittable starting fabric with the dry ice, frozen water or the air-particle mixture is preferably carried out at a speed of 100 m / s to 500 m / s at a feed rate of the outlet nozzle from 2.5 m / min 12, 5 m / min, more preferably from 2.5 m / min to 5 m / min.

The splitting into the elementary filaments is advantageously carried out at pressures of from 0.5 bar to 16 bar, preferably from 0.5 bar to 6 bar, particularly preferably from 0.5 to 2 bar.

Furthermore, a particularly suitable for the aforementioned method according to the invention device is to be provided which allows this method in a simple manner.

For this purpose, the device for splitting a fabric from at least partially split yarns, fibers or filaments of at least two elementary filaments, in particular according to a method of claims 1 to 7, at least one can be directed against the splittable starting fabric outlet nozzle for firing the at least one splittable surface of the cleavable starting fabric with dry ice, with frozen water or with an air-particle mixture.

Advantageously, internals for comminuting the dry ice, the frozen water or the air-particle mixture are arranged in at least one outlet nozzle.

Embodiment of the invention

In Fig. 1

ist eine REM-Aufnahme eines 100-fach vergrößerten Ausschnitts der Oberfläche eines erfindungsgemäß mit Trockeneis-Pellets bei 2 bar gesplitteten und zuvor thermisch vorverfestigten Spinnvliesstoffs aus segmentierten PET/PA6-Piefasern mit einem Gewichtsverhältnis von 70 : 30 gezeigt,

in Fig. 2

ist eine REM-Aufnahme eines 100-fach vergrößerten Ausschnitts der Oberfläche eines erfindungsgemäß mit Trockeneis-Schnee bei 2 bar gesplitteten (nicht-thermisch-vorverfestigten) Spinnvliesstoffs aus segmentierten PET/PA6-Piefasem mit einem Gewichtsverhältnis von 70: 30 gezeigt und

in Fig. 3

ist eine REM-Aufnahme eines 100-fach vergrößerten Ausschnitts der Oberfläche eines erfindungsgemäß mit Trockeneis-Schnee bei 1 bar gesplitteten (nicht-thermisch-vorverfestigten) Spinnvliesstoffs aus segmentierten PET/PA6-Piefasem mit einem Gewichtsverhältnis von 70 : 30 gezeigt.

The object of the invention will be explained in more detail below with reference to examples and figures.

In Fig. 1

is a SEM image of a 100-fold enlarged section of the surface according to the invention with dry ice pellets split at 2 bar and previously thermally pre-bonded spunbonded nonwoven fabric from segmented PET / PA6 pief fibers with a weight ratio of 70: 30 shown

in Fig. 2

is a SEM micrograph of a 100-fold enlarged section of the surface of an inventive dry ice snow at 2 bar split (non-thermally pre-bonded) spunbonded fabric of segmented PET / PA6 Piefasem shown with a weight ratio of 70: 30 and

in Fig. 3

is an SEM image of a 100-fold enlarged section of the surface of an inventive dry ice snow at 1 bar split (non-thermally preconsolidated) spunbonded nonwoven fabric from segmented PET / PA6 piefasem having a weight ratio of 70:30.

Scanning electron micrographs (SEM images) were taken using a JEOL JSM-6480LV low-pressure scanning electron microscope under an acceleration voltage of 20 kV.

Example 1:

According to Example 1, a spunbonded nonwoven fabric, in particular a spunbonded nonwoven fabric, from bicomponent endless filaments with a piezoelectric structure with 16 segments consisting of alternating polyethylene terephthalate / polyamide 6 (PET / PA6) in a weight ratio of 70: 30, bombarded with dry ice pellets.

For this purpose, the spunbonded fabric is minimally needled and thus minimally mechanically solidified, so that the spunbonded fabric can be transported. In addition, the spunbonded fabric is thermally preconsolidated, wherein the thermal preconsolidation takes place on a heatable platen press in a period of 30 seconds at a temperature of 150 ° C and a pressure of 300 bar.

For the splitting of the filaments in the spunbonded fabric, the spunbonded fabric is placed at an angle of 90 ° below the outlet nozzle of the dry ice pellets. The shape of the nozzle is a wide-spout nozzle with a rectangular exit area of 50 mm x 4 mm. This nozzle is used to distribute the energy over as large an area as possible, with the use of, for example, a round nozzle being suitable in principle. Subsequently, the spunbond fabric is bombarded vertically with the dry ice pellets.

Polyethylene terephthalate (crystalline) has a glass transition temperature (Tg) of about 80 ° C and a melting temperature of about 255 ° C according to ISO 11359 according to ISO 75 HDT / A (1.8 MPa) and polyamide 6 has according to ISO 75 HDT / A (1.8 MPa) has a glass transition temperature (Tg) of about 65 ° C and a melting temperature of about 220 ° C according to ISO 11359).

The dry ice pellets have a diameter of about 3 mm and a length of 1 cm. At a density of dry ice of 1.56 g / cm ³ , a pellet weighs about 0.11 g (mass m).

The bombardment with dry ice pellets takes place with a flow rate of 50 kg / h at a speed (v) of the dry ice pellets of 300 m / s.

Thus, the kinetic energy (E _kin = 0.5 mv ² = 0.5 x 0.11 x ^10-3 kg x (300 m / s) ² = 4.95 kg m ² / s ² ) of the dry ice pellets 4.95 joules.

The distance between the exit nozzle and the surface of the splittable starting sheet is between 10 mm and 100 mm, preferably between 25 mm and 75 mm.

The pressure of the dry ice pellets in the bombardment of the spunbonded fabric is 2 bar. The feed speed of the outlet nozzle is 5 m / min.

The FIG. 1 shows a scanning electron micrograph of the spunbonded fabric of Example 1.

Example 2:

In example 2, in contrast to example 1, dry ice snow with a particle size of about 0.1 mm × 0.5 mm is used instead of the dry ice pellets. The dry ice snow weighs 0.0105 g (mass m).

The bombardment with dry ice snow takes place at a speed (v) of 300 m / s.

Thus, the kinetic energy (E _kin = 0.5 mv ² = 0.5 x 0.0105 x ^10-3 kg x (300 m / s) ² = 0.4725 kg m ² / s ² ) of the dry ice snow 0.4725 joules.

In addition, the spunbonded nonwoven fabric used is made of bicomponent filaments having a pie structure with 16 segments, consisting of polyethylene terephthalate / polyamide 6 in a weight ratio of 70: 30. In contrast to the procedure in Example 1, the nonwoven fabric is not thermally preconsolidated. Otherwise, the process is carried out analogously to the conditions of Example 1, wherein only dry ice snow is used instead of the dry ice pellets.

The FIG. 2 shows a scanning electron micrograph of the spunbonded fabric of Example 2.

Due to the lack of thermal preconsolidation, the filaments are more mobile than those according to Example 1.

Example 3:

In the method according to Example 3, a spunbonded nonwoven fabric of bicomponent filaments having a pie structure with 16 segments, consisting of polyethylene terephthalate / polyamide 6 in a weight ratio of 70: 30 used. The procedure is analogous to Example 2 with dry ice snow instead of dry ice pellets. In contrast to Example 2, the pressure of the dry ice snow in Example 3 in the bombardment of the spunbonded fabric only 1 bar instead of 2 bar.

The FIG. 3 shows a scanning electron micrograph of the spunbonded fabric of Example 3.

This procedure according to Example 3 shows that the splitting into the elementary filaments is still well possible even at a pressure of 1 bar.

Claims (7)

1. Method of forming a fabric comprising at least partially split yarns, fibers or filaments that are formed of at least two elementary filaments, characterized in that a splittable starting fabric is split by treatment, more particularly bombardment, with dry ice, with frozen water or with an air-particle mixture at a temperature of at least 20°C to 30°C below the glass transition temperature (Tg) of the polymers used as yarns, fibers or filaments at least partially into the elementary filaments.
2. Method according to Claim 1 wherein a fibrous nonwoven web, more particularly a spunbonded fibrous nonwoven web, is used as splittable starting fabric.
3. Method according to Claim 1 or 2 wherein a preconsolidated fibrous nonwoven web is used as splittable starting fabric.
4. Method according to any one of the preceding claims wherein the yarns, fibers or filaments have at least two elementary filaments selected from polymer pairs or blends from polyolefins, polyesters, polyamides and/or polyurethanes in any desired combination.
5. Method according to any one of the preceding claims wherein the treatment, more particularly the bombardment, onto the surface of the splittable starting fabric with said dry ice, said frozen water or said air-particle mixture is effected under an angle of incidence (α) of 0.1° to 180°, preferably 45° to 135° and more preferably 90°.
6. Method according to any one of the preceding claims wherein the kinetic energy of the particles of said dry ice, of said frozen water or of said air-particle mixture is not less than 0.4 joule.
7. Method according to any one of the preceding claims wherein the splitting into the elementary filaments is effected at pressures of 0.5 bar to 16 bar, preferably 0.5 to 6 bar and more preferably 0.5 to 2 bar.

Images