Title of Invention	METHOD AND DEVICE FOR PRODUCING A NONWOVEN FROM CONTINUOUS FILAMENTS
Abstract	A method for producing a nonwoven from continuous filaments is described, wherein filaments are produced of which at least some exhibit natural crimping. The filaments are deposited in the depositing region' of the deposited filament is conveyed with the conveying device in the direction of a bonding device. A gas stream (G) flowing along the surface of the deposited filament in the conveying direction of the deposited filament is generated.

Title of Invention

METHOD AND DEVICE FOR PRODUCING A NONWOVEN FROM CONTINUOUS FILAMENTS

Abstract

A method for producing a nonwoven from continuous filaments is described, wherein filaments are produced of which at least some exhibit natural crimping. The filaments are deposited in the depositing region' of the deposited filament is conveyed with the conveying device in the direction of a bonding device. A gas stream (G) flowing along the surface of the deposited filament in the conveying direction of the deposited filament is generated.

Full Text	FIELP OF INVENTION The invention relates to a method for producing a nonwoven from continuous filaments. In addition, the invention relates to a device for carrying out such a method. In is within the scope of the invention that the continuous filaments consist of a thermoplastic material. As a result of their quasi-continuous length, continuous filaments differ from staple fibres which have substantially shorter lengths of, for example, 10 to 60 mm. The continuous filaments are normally produced using a spinning device or using a spinneret. BACKGROUND OF THE INVENTION Basically, it is known from practice to produce voluminous nonwovens known as "high loft nonwovens" using staple fibres. In this case, the fibre baling is normally bonded by hot air bonding using a continuous flow method. These nonwovens are used, inter alia, in the hygiene industry (for example, as distributor layers 'in nappies) and in filter technology. Attempts have already been made to produce comparably thick or voluminous nonwovens from continuous filaments, where multicomponent filaments with natural crimping have been used. In this case, however, filament baling or a nonwoven with an irregular or inhomogeneous structure is obtained'. This is at least partly attributable to the fact that the activation of the crimping can result in shrinkage forces which result in ripping of the filament baling or the nonwoven. The result is unacceptable products. OBJECTS OF THE INVENTION However, the technical object of the invention is to provide a method for producing a nonwoven from continuous filaments whereby thick or voluminous nonwovens with a very regular or homogeneous structure can be produced. In addition, it is the technical problem of the invention to provide a corresponding device. DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION In order to solve this technical object, the invention teaches a method for producing a nonwoven from continuous filaments, wherein filaments are produced of which at least some exhibit natural crimping, wherein the filaments are deposited in the depositing region of a conveying device to form the deposited filament and wherein the deposited filament is conveyed with the conveying device in the direction of a bonding device and wherein a gas stream flowing along in the conveying direction of the deposited filament on the surface of the deposited filament is generated. In principle, single-layer or multi-layer nonwovens consisting completely of filaments with natural crimping can be produced within the scope of the invention. However, it is also within the scope of the invention to produce a single-layer nonwoven comprising a mixture of filaments having natural crimping and non-crimping filaments. In multilayer nonwovens the individual layers can be formed from filaments with natural crimping or from non-crimping filaments or of mixtures of filaments with natural crimping with non-crimping filaments. Appropriately, a multi-layer nonwoven according to the invention comprises at least one layer consisting exclusively of filaments with natural crimping or a mixture of filaments with natural crimping with non-crimping filaments. The continuous filaments are initially spun from a spinning device or from a spinneret. These filaments are then appropriately cooled. It is within the scope of the invention that the filaments are stret'ched in a stretching device. The cooling and stretching can in particular take place in a combined cooling and stretching device. Before the filaments are deposited in the depositing region, they are preferably guided through a diffuser. The diffuser is then arranged between the stretching device or between the combined cooling and stretching device and the depositing region. The filaments emerging from the spinning device are preferably treated by the Reicofil III method (DE-PS 196 20 379) or by the Reicofil IV method (EP-OS 1 340 843). Filaments with natural crimping means in particular filaments or bicomponent/multicomponent filaments in which crimping occurs after the drafting. In this case, the crimping therefore begins as soon as the stretching forces or the air stretching forces no longer act on the filaments. In this case, the crimping can initially take place before the depositing, i.e. between the drafting device and the depositing region, in particular in a preferably provided diffuser. This crimping which takes place before the filaments are deposited is described as "primary crimping". However, the filaments with natural crimping can in particular also develop (further) crimping after deposition. This crimping which takes place after deposition is described as "secondary crimping". Filaments with natural crimping preferably means within the scope of the invention filaments having radii of curvature of less than 5 mm after deposition on the conveying device in the stress-relieved state. These filaments then exhibit corresponding crimping having the aforesaid radii of curvature over most of their length. According to a very preferred embodiment of the invention, the filaments with natural crimping are bicomponent filaments or multicomponent filaments which preferably exhibit a side- by-sido arrangement. According to, another preferred embodiment, bicomponent filaments or multicomponent filaments having an acentric core/cladding arrangement can also be used as filaments with natural crimping. It is within the scope of the invention that the method according to the invention is carried out under the condition that crimping of the filaments (with natural crimping) takes place after stretching the filaments and before depositing the filaments. This therefore comprises the aforesaid primary crimping of the filaments. It is furthermore within the scope of the invention that crimping of the filaments (with natural crimping) takes place after depositing the filaments on the conveying device. This comprises the aforesaid secondary crimping. The conveying device appropriately consists of a conveyor belt or a plurality of successively connected conveyor belts. In this case, at least one conveyor belt is configured in the depositing region of the filaments as a gas-permeable (air-permeable) or gas-permeable (air- permeable) sieve belt. Such a sieve belt in particular comprises a continuous belt guided over deflecting rollers. According to a preferred embodiment of the invention, the filaments are deposited on the sieve belt as a conveying device or as a component of a conveying device to form the deposited filament and the deposited filament is exposed to suction air in a suction region of the sieve belt. It is also within the scope of the invention that the suction region comprises the depositing region for the filaments and appropriately also a region after this depositing region in the conveying direction. In order to achieve the action of suction air, preferably at least one suction device is located below the sieve belt. With such a suction device air is sucked through the sieve belt so that the filament or the deposited filament on the sieve belt is, as if were, sucked. This leads to a certain stabilisation of the deposited filament. As a result of the suction action, the deposited filament has a relatively small thickness (for example, a thickness of about 2 to 3 mm). In this suction region, the deposited filament is (still) fixed and held down on the sieve belt by a suction air field to survive the relative high air speeds in the depositing region without undesirable . displacements and inhomdgeneities. When leaving the. suction region, the deposited filament jumps up, as it wefe, particularly as a result of the . secondary crimping. The deposited filament then has a substantially greater thickness (for example, a thickness of 3 cm with 40 g/m2 weight per unit area) . According to the invention, a gas stream flowing along the surface of deposited filament is generated in the conveying direction of the deposited filament. The fact that the gas stream flows along the surface of the deposited filaments means in particular that the gas stream flows parallel or substantially parallel to the surface of the deposited filament or flows parallel or substantially parallel to the surface of the conveying device or the sieve belt. It is also within the scope of the invention that the gas stream flows past the surface of the deposited filament in the conveying direction behind the suction region. The gas stream is preferably an air stream. As has been stated above, on leaving the suction region the deposited filament as it were jumps up in particular as a result of the secondary crimping and a relatively thick deposited filament is then obtained. The invention is based on the finding that this deposited filament is endangered when jumping up or in the jumped-up state firstly because shrinkage forces from the second crimping can destroy the uniformity of the deposited filament and secondly because air forces act upon the jumped-up deposited filament and can as it were open this deposited filament. These air forces result from the fact that the deposited filament is moved at the speed of the conveying device or the sieve ... belt, as it were, against standing ambient air. The invention is now based on the finding that the deposited filament can be effectively stabilised against said negative effects by the gas stream flowing along the surface of the deposited filament in the conveying direction. In other words, the deposited filament according to the invention is stabilised in particular in the suction-free region by a forced air flow. It is within the scope of the invention that the flow rate of the gas stream (air flow) corresponds to at least half the conveying speed of the deposited filament, preferably at least 80%, more preferably at least 90% and very preferably at least 95% of the conveying speed of the deposited filament. According to a particularly preferred embodiment, the flow rate of the gas stream (air flow) corresponds to ' at least the cbnveying speed or approximately the conveying speed of the deposited filament. According to one embodiment of the invention, the flow rate of the gas stream (air flow) is somewhat higher than the conveying speed of the deposited filament and preferably a maximum of 20%, more preferably a maximum of 15% and very preferably a maximum of 10% higher than the conveying speed of the deposited filament. According to a very recommended embodiment which acquires quite particular importance within the scope of the invention, the deposited filament is bonded with at least one fluid medium in the bonding device, preferably with at least one hot fluid medium. It is at. the same time within the scope of the invention that the deposited filament is exposed to the hot fluid medium in the bonding device with the proviso that the deposited filament is pressed against the conveying direction or against a gas-permeable sieve belt. At the same time, the surface of the deposited filament is appropriately exposed to the transverse action by forces of the hot fluid medium. The deposited filament is thereby pressed towards the conveying direction or onto the sieve belt. It is also within the scope of the invention that the hot fluid medium flows through the deposited filament and the gas-permeable sieve belt. This bonding preferably takes place in a bonding chamber through which the conveying device or the sieve belt with the deposited filament is guided. The bonding is appropriately carried out as hot air bonding. The fluid medium flows in the bonding device preferably perpendicular to the surface of the deposited filament and preferably from above onto the deposited filament. At the same time, it is within the scope of the invention that the area of the deposited filament is acted upon by the fluid medium, preferably by the hot fluid medium (-i.e. not only linearly). According to a very preferred embodiment of the invention, the gas stream flowing along the surface of the deposited filament is generated by means of the fluid medium flowing in the bonding device. In other words, the fluid medium (preferably the hot air flowing there) flowing in the bonding device is the driving force for producing the gas stream flowing along the surface of the deposited filament. At the same time, it is within the scope of the invention that the gas stream flowing according to the invention is at least substantially produced by a venturi effect. According to another preferred embodiment of the invention, gas is blown in and/or sucked in and is deflected by means of at least one flow guiding device to the gas stream flowing along the surface of the deposited filament. The at least one flow guiding device is preferably a flow baffle or a curved flow baffle. The subject matter of the invention is also a device for. producing a nonwoven of continuous filaments which exhibit at least some natural crimping, comprising at least one spinning device for producing filaments and comprising a conveying device with a depositing region in which the filaments can be deposited to form the deposited filament, wherein furthermore a bonding device is provided for bonding the filaments and wherein at least one generating device is provided whereby a gas stream flowing along the surface of the deposited filament in the conveying direction of the deposited filament can be generated between the depositing region and the bonding device. This gas stream according to the invention preferably flows in the conveying direction behind the suction region along the surface of the deposited filament and preferably as far as the bonding device. It is within the scope of the invention that a stretching device for stretching the filaments is arranged between the spinning device and the depositing region. It is furthermore within the scope of the invention to provide a cooling device between the spinning device and the stretching device. According to one variant, a combined cooling and stretching device is used. According to a particularly preferred embodiment of the invention, a diffuser for depositing the filaments is arranged between the stretching device and the depositing region. This diffuser is particularly important within the scope of the invention. The diffuser appropriately has diverging diffuser walls towards the depositing region. The invention is based on the finding that the method according to the invention and the device according to the invention can produce thick or voluminous nonwovens which nevertheless are distinguished by homogeneous properties and a homogeneous or uniform structure. As a result, nonwovens having optimal properties and optimal quality can be produced. It should also be stressed that these nonwovens of suitable thickness and homogeneity can be reproducibly produced. It should also be stressed that with a view to the considerable advantages achieved, the method according to. the invention can be carried out with relatively little complexity and in this respect only causes relatively low costs. Existing devices can easily be retrofitted with the components according to the invention. The invention is explained in detail hereinafter with reference to drawings showing only one exemplary embodiment. Shown in schematic view: BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS Fig.1 is a section through a part of a device according to the invention, Fig.2 is a section through another part of a device according to the invention, Fig.3 is a particular embodiment of the subject matter according to Fig.2 and Fig.4 is another embodiment of the subject matter according to fig.2. The figures show a device for carrying out a method for producing a nonwoven of continuous filaments, where filaments 1 are produced, of which at least some exhibit natural crimping. According to one embodiment, the nonwoven may be a single-layer nonwoven which either consists exclusively of filaments with natural crimping or of a mixture of filaments with natural crimping and non-crimping filaments. The fraction of filaments with natural crimping is preferably at least 20 wt. %, more preferably at least 30 wt. %. A multi-layer nonwoven where at least one layer (as described previously) comprises filaments with natural crimping can also be produced within the scope of the method according to the invention. It can be seen from Fig.l that the device according to the invention comprises a spinning device 2 for producing the filaments 1 and appropriately a cooling chamber 3 located below the spinning device 2 into which process air can be introduced for cooling the filaments 1. Also provided is a stretching device 4 for aerodynamic stretching of the filaments 1. Preferably located below the stretching device 4 and in the exemplary embodiment is a diffuser 5 which is merely shown schematically. A laying unit consisting of two diffusers connected one after the other can also be provided, for example, below the stretching device 4. A conveying device configured as an air-permeable sieve belt 6 is provided underneath the diffuser 5. In a depositing region 7 of this sieve belt 6 the filaments 1 are deposited to form a deposited filament 8. In the exemplary embodiment the deposited filament 8 is formed from filaments 1 with natural crimping, the filaments 1 preferably comprising bicomponent filaments with a side-by-side arrangement. After the stretching or below the stretching device 4 a first crimping (primary crimping) of these filaments 1 takes place in the diffuser 5. The deposited filament 8 is conveyed to the left in the figures in the direction of a bonding device 9 using the sieve belt 6. In the enlarged section in Fig. 2 it is shown that the deposited filament 8 is constructed as a shingle-like deposit. Newly laid filaments 1 are laid . on previously deposited filaments 1 and in this way as it were, a slate-like deposit is formed. In a suction region 10 of the sieve belt 6, the deposited filament 8 is exposed to suction air. In other words, air is preferably sucked from below through the sieve belt 6 by means of a suction device not shown and the filaments 1 or deposited filament 8 are thereby sucked as it were onto the sieve belt 6. A certain stabilisation of the deposited filament 8 is hereby achieved. The suction region 10 extends over the depositing region 7 for the filaments 1 into a region 11 located in the conveying direction after the depositing region 7. The action i of the suction air fixes and holds down the deposited filament 8 in this suction region 10 on the sieve belt 6 so that the deposited filament 8 has a relatively small thickness (for example, a thickness of 2 to 3 mm). When the deposited filament 8 leaves the suction region 10 during further conveyance with the sieve belt 6, the deposited filament 8 jumps up especially as a result of further crimping (secondary crimping) and results in a deposited filament 8 having a substantially greater thickness (for example, having a thickness of about 3 cm). This "jumping up" is indicated by a corresponding increase in the thickness of the deposited. filament 8 in Figs. 2 to 4. In particular, two disadvantageous effects can be associated with the jumping- up of the deposited filament 8. Firstly, shrinkage effects of the secondary crimping can destroy the uniform structure of the deposited filament 8. In addition, air forces can as i it were open the deposited filament 8 since the. deposited filament 8 is moved at the speed of the sieve belt towards the standing ambient air. This opening can occur in particular as a result of the shingle-like deposition shown in the enlarged section in Fig. 2. i According to the invention, a gas stream flowing along the surface of the deposited filament 8 in the conveying direction of the deposited filament 8 is now formed in the area where the deposited filament 8 jumps up or in the area of the secondary crimping, as is-indicated by an arrow G in the figures. This gas stream G flows in the conveying direction of the deposited filament 8 after the suction. region 10 along the surface of the deposited filament 8. The invention is based on the finding that this gas stream G according to the invention can stabilise the jumped-up deposited filament 8 and can reliably and effectively counteract the previously described negative effects ori the deposited filament; 8. The flow rate of this gas stream G is preferably at least equal to the conveying speed of the deposited filament 8 or the sieve belt speed, or the flow rate of the gas stream G is somewhat higher than the conveying speed of the deposited filament 8 or than the sieve belt speed. The deposited filament 8 is fed into a bonding chamber 1.2 with the sieve belt 6, wherein bonding of the deposited filament 8 with a hot fluid medium, preferably hot air bonding, takes place.'The hot fluid medium or the hot air flows from above vertically to the surface of the deposited filament 8 flat onto the deposited filament 8. This is indicated schematically by the appropriate arrows in Figs. 2 to 4. Figure 3 shows a particular embodiment' for producing a gas stream G according to the invention. An upper cover 13 is provided here and the gas stream G flows between this cover 13 and the sieve belt 6 or the surface of the deposited filament 8 in the direction of the bonding device 9. The cover 13 is appropriately arranged parallel or substantially parallel, to the sieve belt 6 or to the surface of the deposited filament 8. According to a preferred embodiment and in the exemplary embodiment according to Fig. 3, the gas stream G flowing along the surface of the deposited filament 8 is produced by means of the fluid medium flowing into the bonding device 9. In i other words, the fluid medium flowing into the bonding chamber 12 forms the driving force for the gas stream G. Figure 4shows another preferred embodiment. Here air is blown from above into the area of the secondary crimping (area of the jumped-up deposited filament). The blown-in gas is deflected towards the gas stream G flowing along the surface of the deposited filament 8 by means of suitably curved.flow baffles.14. The gas can also be sucked in here. Appropriately and in the exemplary embodiment, the gas stream G flows perpendicularly or substantially perpendicularly to the direction of flow of the fluid medium in the bonding device 9 or in the bonding chamber 1:2. According to a preferred embodiment and in the exemplary embodiment according to the figures, only one air-permeable sieve belt 6 is provided whereby the deposited filament 8 is conveyed from the depositing region 7 via the region 11 and via the region of secondary crimping (region of jumped-up deposited filament 8) into the bonding chamber 12. The sieve belt 6 is guided in the usual manner as a continuous belt over corresponding deflecting rollers. Of particular importance within the scope of the invention is a preferred embodiment shown schematically in Fig. 1. According to this, the unit is formed from a, cooling chamber 3, stretching device 4 and diffuser 5 as a closed system, apart from an air supply in the cooling chamber 3 and apart from at least one air inlet in the area of the diffuser 5. In other words, the unit comprising the cool.ing chamber 3 and stretching device is designed as closed apart from the air supply in the cooling chamber 3. This closed embodiment of the device has proved to be quite particularly effective with regard ,to optimal nonwoven quality and in particular in combination with the further features according to the invention claimed here. WE CLAIM 1. A method for producing a nonwoven from continuous filaments, wherein filaments (1) are produced of which at least some exhibit natural crimping, characterized in that the filaments (1) are deposited in a depositing region (7) of a conveying device to form a deposited filament (8) and wherein the deposited filament (8) is conveyed with the conveying device in the direction of a bonding device (9), and in that a gas stream (G) flowing along in the conveying direction of the deposited filament (8) on the surface of the deposited filament (8) is generated. 2. The method as claimed in claim 1, wherein the filaments (1) with natural crimping are bicomponent filaments or multicomponent filaments which preferably exhibit a side-by-side arrangement. 3. The method as claimed in any one of claims 1 or 2, wherein a crimping of the filaments (1) takes place after stretching the filaments (1) and before depositing the filaments (1). 4. The method as claimed in any one of claims 1 or 3, wherein crimping of the filaments (1) takes place after depositing the filaments (1). 5. The method as claimed in any one of claims 1 to 4, wherein the filaments (1) are deposited on a sieve belt (6) as a conveying device or as a component of a conveying device to form the deposited filament (8) and wherein the deposited filament (8) is exposed to suction air in a suction region (10) of the sieve belt (6). 6. The method as claimed in any one of claims 1 to 5, wherein the gas stream (G) flows in the conveying direction behind the suction region (10) past the surface of the deposited filament (8). 7. The method as claimed in any one of claims 1 to 6, wherein the flow rate of the gas stream (G) corresponds to at least half the conveying speed of the deposited filament (8) and preferably corresponds to at least the conveying speed or approximately the conveying speed of the deposited filament (8). 8. The method as claimed in any one of claims 1 to 7, wherein the deposited filament (8) is bonded with at least one fluid medium, preferably with at least one hot fluid medium. 9. The method as claimed in any one of claims 1 to 8, wherein the gas stream (G) flowing along the surface of the deposited filament (8) is generated by means of the fluid medium flowing in the bonding device (9). 10. The method as claimed in any one of claims 1 to 9, wherein gas is blown in and/or sucked in and is deflected by means of at least one flow guiding device to the gas stream (G) flowing along the surface of the deposited filament (8). 11. A device for producing a nonwoven of continuous filaments which exhibit at least some natural crimping, comprising at least one spinning device (2) for producing filaments (1) and comprising a conveying device with a depositing region (7) in which the filaments (1) can be deposited to form a deposited filament (8), wherein furthermore a bonding device (9) is provided for bonding the filaments (1) and wherein at least one generating device is provided whereby a gas stream (G) flowing along the surface of the deposited filament (8) in the conveying direction of the deposited filament (8) can be generated between the depositing region (7) and the bonding device (9). 12. The device as claimed in claim 11, wherein a stretching device (4) for stretching the filaments (1) is arranged between the spinning device (2) and the depositing region (7). 13. The device as claimed in one of claims 11 or 12, wherein a diffuser (5) is arranged between the stretching device (4) and the depositing region (7). ABSTRACT METHOD AND DEVICE FOR PRODUCING A NONWOVEN FROM CONTINUOUS FILAMENTS A method for producing a nonwoven from continuous filaments is described, wherein filaments are produced of which at least some exhibit natural crimping. The filaments are deposited in the depositing region' of the deposited filament is conveyed with the conveying device in the direction of a bonding device. A gas stream (G) flowing along the surface of the deposited filament in the conveying direction of the deposited filament is generated.

Full Text

FIELP OF INVENTION
The invention relates to a method for producing a nonwoven from continuous
filaments. In addition, the invention relates to a device for carrying out such a
method. In is within the scope of the invention that the continuous filaments
consist of a thermoplastic material. As a result of their quasi-continuous length,
continuous filaments differ from staple fibres which have substantially shorter
lengths of, for example, 10 to 60 mm. The continuous filaments are normally
produced using a spinning device or using a spinneret.
BACKGROUND OF THE INVENTION
Basically, it is known from practice to produce voluminous nonwovens known as
"high loft nonwovens" using staple fibres. In this case, the fibre baling is
normally bonded by hot air bonding using a continuous flow method. These
nonwovens are used, inter alia, in the hygiene industry (for example, as
distributor layers 'in nappies) and in filter technology. Attempts have already
been made to produce comparably thick or voluminous nonwovens from
continuous filaments, where multicomponent filaments with natural crimping
have been used. In this case, however, filament baling or a nonwoven with an
irregular or inhomogeneous structure is obtained'. This is at least partly
attributable to the fact that the activation of the crimping can result in shrinkage
forces which result in ripping of the filament baling or the nonwoven. The result
is unacceptable products.
OBJECTS OF THE INVENTION
However, the technical object of the invention is to provide a method for
producing a nonwoven from continuous filaments whereby thick or voluminous
nonwovens with a very regular or homogeneous structure can be produced. In

addition, it is the technical problem of the invention to provide a corresponding
device.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
In order to solve this technical object, the invention teaches a method for
producing a nonwoven from continuous filaments, wherein filaments are
produced of which at least some exhibit natural crimping,
wherein the filaments are deposited in the depositing region of a conveying
device to form the deposited filament and wherein the deposited filament is
conveyed with the conveying device in the direction of a bonding device
and wherein a gas stream flowing along in the conveying direction of the
deposited filament on the surface of the deposited filament is generated.
In principle, single-layer or multi-layer nonwovens consisting completely of
filaments with natural crimping can be produced within the scope of the
invention. However, it is also within the scope of the invention to produce a
single-layer nonwoven comprising a mixture of filaments having natural crimping
and non-crimping filaments. In multilayer nonwovens the individual layers can be
formed from filaments with natural crimping or from non-crimping filaments or of
mixtures of filaments with natural crimping with non-crimping filaments.
Appropriately, a multi-layer nonwoven according to the invention comprises at
least one layer consisting exclusively of filaments with natural crimping or a
mixture of filaments with natural crimping with non-crimping filaments.
The continuous filaments are initially spun from a spinning device or from a
spinneret. These filaments are then appropriately cooled. It is within the scope of
the invention that the filaments are stret'ched in a stretching device. The cooling
and stretching can in particular take

place in a combined cooling and stretching device. Before
the filaments are deposited in the depositing region, they
are preferably guided through a diffuser. The diffuser is
then arranged between the stretching device or between the
combined cooling and stretching device and the depositing
region. The filaments emerging from the spinning device are
preferably treated by the Reicofil III method (DE-PS 196 20
379) or by the Reicofil IV method (EP-OS 1 340 843).
Filaments with natural crimping means in particular
filaments or bicomponent/multicomponent filaments in which
crimping occurs after the drafting. In this case, the
crimping therefore begins as soon as the stretching forces
or the air stretching forces no longer act on the
filaments. In this case, the crimping can initially take
place before the depositing, i.e. between the drafting
device and the depositing region, in particular in a
preferably provided diffuser. This crimping which takes
place before the filaments are deposited is described as
"primary crimping". However, the filaments with natural
crimping can in particular also develop (further) crimping
after deposition. This crimping which takes place after
deposition is described as "secondary crimping". Filaments
with natural crimping preferably means within the scope of
the invention filaments having radii of curvature of less
than 5 mm after deposition on the conveying device in the
stress-relieved state. These filaments then exhibit
corresponding crimping having the aforesaid radii of
curvature over most of their length. According to a very
preferred embodiment of the invention, the filaments with
natural crimping are bicomponent filaments or
multicomponent filaments which preferably exhibit a side-
by-sido arrangement. According to, another preferred
embodiment, bicomponent filaments or multicomponent
filaments having an acentric core/cladding arrangement can
also be used as filaments with natural crimping.

It is within the scope of the invention that the method
according to the invention is carried out under the
condition that crimping of the filaments (with natural
crimping) takes place after stretching the filaments and
before depositing the filaments. This therefore comprises
the aforesaid primary crimping of the filaments. It is
furthermore within the scope of the invention that crimping
of the filaments (with natural crimping) takes place after
depositing the filaments on the conveying device. This
comprises the aforesaid secondary crimping.
The conveying device appropriately consists of a conveyor
belt or a plurality of successively connected conveyor
belts. In this case, at least one conveyor belt is
configured in the depositing region of the filaments as a
gas-permeable (air-permeable) or gas-permeable (air-
permeable) sieve belt. Such a sieve belt in particular
comprises a continuous belt guided over deflecting rollers.
According to a preferred embodiment of the invention, the
filaments are deposited on the sieve belt as a conveying
device or as a component of a conveying device to form the
deposited filament and the deposited filament is exposed to
suction air in a suction region of the sieve belt. It is
also within the scope of the invention that the suction
region comprises the depositing region for the filaments
and appropriately also a region after this depositing
region in the conveying direction. In order to achieve the
action of suction air, preferably at least one suction
device is located below the sieve belt. With such a suction
device air is sucked through the sieve belt so that the
filament or the deposited filament on the sieve belt is, as
if were, sucked. This leads to a certain stabilisation of
the deposited filament. As a result of the suction action,
the deposited filament has a relatively small thickness
(for example, a thickness of about 2 to 3 mm). In this
suction region, the deposited filament is (still) fixed and
held down on the sieve belt by a suction air field to

survive the relative high air speeds in the depositing
region without undesirable . displacements and
inhomdgeneities. When leaving the. suction region, the
deposited filament jumps up, as it wefe, particularly as a
result of the . secondary crimping. The deposited filament
then has a substantially greater thickness (for example, a
thickness of 3 cm with 40 g/m2 weight per unit area) .
According to the invention, a gas stream flowing along the
surface of deposited filament is generated in the conveying
direction of the deposited filament. The fact that the gas
stream flows along the surface of the deposited filaments
means in particular that the gas stream flows parallel or
substantially parallel to the surface of the deposited
filament or flows parallel or substantially parallel to the
surface of the conveying device or the sieve belt. It is
also within the scope of the invention that the gas stream
flows past the surface of the deposited filament in the
conveying direction behind the suction region. The gas
stream is preferably an air stream.
As has been stated above, on leaving the suction region the
deposited filament as it were jumps up in particular as a
result of the secondary crimping and a relatively thick
deposited filament is then obtained. The invention is based
on the finding that this deposited filament is endangered
when jumping up or in the jumped-up state firstly because
shrinkage forces from the second crimping can destroy the
uniformity of the deposited filament and secondly because
air forces act upon the jumped-up deposited filament and
can as it were open this deposited filament. These air
forces result from the fact that the deposited filament is
moved at the speed of the conveying device or the sieve
...
belt, as it were, against standing ambient air. The
invention is now based on the finding that the deposited
filament can be effectively stabilised against said
negative effects by the gas stream flowing along the

surface of the deposited filament in the conveying
direction. In other words, the deposited filament according
to the invention is stabilised in particular in the
suction-free region by a forced air flow.
It is within the scope of the invention that the flow rate
of the gas stream (air flow) corresponds to at least half
the conveying speed of the deposited filament, preferably
at least 80%, more preferably at least 90% and very
preferably at least 95% of the conveying speed of the
deposited filament. According to a particularly preferred
embodiment, the flow rate of the gas stream (air flow)
corresponds to ' at least the cbnveying speed or
approximately the conveying speed of the deposited
filament. According to one embodiment of the invention, the
flow rate of the gas stream (air flow) is somewhat higher
than the conveying speed of the deposited filament and
preferably a maximum of 20%, more preferably a maximum of
15% and very preferably a maximum of 10% higher than the
conveying speed of the deposited filament.
According to a very recommended embodiment which acquires
quite particular importance within the scope of the
invention, the deposited filament is bonded with at least
one fluid medium in the bonding device, preferably with at
least one hot fluid medium. It is at. the same time within
the scope of the invention that the deposited filament is
exposed to the hot fluid medium in the bonding device with
the proviso that the deposited filament is pressed against
the conveying direction or against a gas-permeable sieve
belt. At the same time, the surface of the deposited
filament is appropriately exposed to the transverse action
by forces of the hot fluid medium. The deposited filament
is thereby pressed towards the conveying direction or onto
the sieve belt. It is also within the scope of the
invention that the hot fluid medium flows through the
deposited filament and the gas-permeable sieve belt. This

bonding preferably takes place in a bonding chamber through
which the conveying device or the sieve belt with the
deposited filament is guided. The bonding is appropriately
carried out as hot air bonding. The fluid medium flows in
the bonding device preferably perpendicular to the surface
of the deposited filament and preferably from above onto
the deposited filament. At the same time, it is within the
scope of the invention that the area of the deposited
filament is acted upon by the fluid medium, preferably by
the hot fluid medium (-i.e. not only linearly).
According to a very preferred embodiment of the invention,
the gas stream flowing along the surface of the deposited
filament is generated by means of the fluid medium flowing
in the bonding device. In other words, the fluid medium
(preferably the hot air flowing there) flowing in the
bonding device is the driving force for producing the gas
stream flowing along the surface of the deposited filament.
At the same time, it is within the scope of the invention
that the gas stream flowing according to the invention is
at least substantially produced by a venturi effect.

According to another preferred embodiment of the invention,
gas is blown in and/or sucked in and is deflected by means
of at least one flow guiding device to the gas stream
flowing along the surface of the deposited filament. The at
least one flow guiding device is preferably a flow baffle
or a curved flow baffle.
The subject matter of the invention is also a device for.
producing a nonwoven of continuous filaments which exhibit
at least some natural crimping, comprising at least one
spinning device for producing filaments and comprising a
conveying device with a depositing region in which the
filaments can be deposited to form the deposited filament,
wherein furthermore a bonding device is provided for
bonding the filaments and wherein at least one generating

device is provided whereby a gas stream flowing along the
surface of the deposited filament in the conveying
direction of the deposited filament can be generated
between the depositing region and the bonding device. This
gas stream according to the invention preferably flows in
the conveying direction behind the suction region along the
surface of the deposited filament and preferably as far as
the bonding device.
It is within the scope of the invention that a stretching
device for stretching the filaments is arranged between the
spinning device and the depositing region. It is
furthermore within the scope of the invention to provide a
cooling device between the spinning device and the
stretching device. According to one variant, a combined
cooling and stretching device is used. According to a
particularly preferred embodiment of the invention, a
diffuser for depositing the filaments is arranged between
the stretching device and the depositing region. This
diffuser is particularly important within the scope of the
invention. The diffuser appropriately has diverging
diffuser walls towards the depositing region.
The invention is based on the finding that the method
according to the invention and the device according to the
invention can produce thick or voluminous nonwovens which
nevertheless are distinguished by homogeneous properties
and a homogeneous or uniform structure. As a result,
nonwovens having optimal properties and optimal quality can
be produced. It should also be stressed that these
nonwovens of suitable thickness and homogeneity can be
reproducibly produced. It should also be stressed that with
a view to the considerable advantages achieved, the method
according to. the invention can be carried out with
relatively little complexity and in this respect only
causes relatively low costs. Existing devices can easily be
retrofitted with the components according to the invention.

The invention is explained in detail hereinafter with reference to drawings
showing only one exemplary embodiment. Shown in schematic view:
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig.1 is a section through a part of a device according to the invention,
Fig.2 is a section through another part of a device according to the invention,
Fig.3 is a particular embodiment of the subject matter according to Fig.2 and
Fig.4 is another embodiment of the subject matter according to fig.2.
The figures show a device for carrying out a method for producing a nonwoven
of continuous filaments, where filaments 1 are produced, of which at least some
exhibit natural crimping. According to one embodiment, the nonwoven may be a
single-layer nonwoven which either consists exclusively of filaments with natural
crimping or of a mixture of filaments with natural crimping and non-crimping
filaments. The fraction of filaments with natural crimping is preferably at least 20
wt. %, more preferably at least 30 wt. %. A multi-layer nonwoven where at least
one layer (as described previously) comprises filaments with natural crimping can
also be produced within the scope of the method according to the invention.
It can be seen from Fig.l that the device according to the invention comprises a
spinning device 2 for producing the filaments 1 and appropriately a cooling
chamber 3 located below the spinning device 2 into which process air can be
introduced for cooling the filaments 1. Also provided is a stretching device 4 for
aerodynamic stretching of the filaments 1. Preferably located below the
stretching device

4 and in the exemplary embodiment is a diffuser 5 which is
merely shown schematically. A laying unit consisting of two
diffusers connected one after the other can also be
provided, for example, below the stretching device 4. A
conveying device configured as an air-permeable sieve belt
6 is provided underneath the diffuser 5. In a depositing
region 7 of this sieve belt 6 the filaments 1 are deposited
to form a deposited filament 8. In the exemplary embodiment
the deposited filament 8 is formed from filaments 1 with
natural crimping, the filaments 1 preferably comprising
bicomponent filaments with a side-by-side arrangement.
After the stretching or below the stretching device 4 a
first crimping (primary crimping) of these filaments 1
takes place in the diffuser 5. The deposited filament 8 is
conveyed to the left in the figures in the direction of a
bonding device 9 using the sieve belt 6. In the enlarged
section in Fig. 2 it is shown that the deposited filament 8
is constructed as a shingle-like deposit. Newly laid
filaments 1 are laid . on previously deposited filaments 1
and in this way as it were, a slate-like deposit is formed.
In a suction region 10 of the sieve belt 6, the deposited
filament 8 is exposed to suction air. In other words, air
is preferably sucked from below through the sieve belt 6 by
means of a suction device not shown and the filaments 1 or
deposited filament 8 are thereby sucked as it were onto the
sieve belt 6. A certain stabilisation of the deposited
filament 8 is hereby achieved. The suction region 10
extends over the depositing region 7 for the filaments 1
into a region 11 located in the conveying direction after
the depositing region 7. The action i of the suction air
fixes and holds down the deposited filament 8 in this
suction region 10 on the sieve belt 6 so that the deposited
filament 8 has a relatively small thickness (for example, a
thickness of 2 to 3 mm). When the deposited filament 8
leaves the suction region 10 during further conveyance with
the sieve belt 6, the deposited filament 8 jumps up

especially as a result of further crimping (secondary
crimping) and results in a deposited filament 8 having a
substantially greater thickness (for example, having a
thickness of about 3 cm). This "jumping up" is indicated by
a corresponding increase in the thickness of the deposited.
filament 8 in Figs. 2 to 4. In particular, two
disadvantageous effects can be associated with the jumping-
up of the deposited filament 8. Firstly, shrinkage effects
of the secondary crimping can destroy the uniform structure
of the deposited filament 8. In addition, air forces can as
i
it were open the deposited filament 8 since the. deposited
filament 8 is moved at the speed of the sieve belt towards
the standing ambient air. This opening can occur in
particular as a result of the shingle-like deposition shown
in the enlarged section in Fig. 2.
i
According to the invention, a gas stream flowing along the
surface of the deposited filament 8 in the conveying
direction of the deposited filament 8 is now formed in the
area where the deposited filament 8 jumps up or in the area
of the secondary crimping, as is-indicated by an arrow G in
the figures. This gas stream G flows in the conveying
direction of the deposited filament 8 after the suction.
region 10 along the surface of the deposited filament 8.
The invention is based on the finding that this gas stream
G according to the invention can stabilise the jumped-up
deposited filament 8 and can reliably and effectively
counteract the previously described negative effects ori the
deposited filament; 8. The flow rate of this gas stream G is
preferably at least equal to the conveying speed of the
deposited filament 8 or the sieve belt speed, or the flow
rate of the gas stream G is somewhat higher than the
conveying speed of the deposited filament 8 or than the
sieve belt speed.
The deposited filament 8 is fed into a bonding chamber 1.2
with the sieve belt 6, wherein bonding of the deposited

filament 8 with a hot fluid medium, preferably hot air
bonding, takes place.'The hot fluid medium or the hot air
flows from above vertically to the surface of the deposited
filament 8 flat onto the deposited filament 8. This is
indicated schematically by the appropriate arrows in Figs.
2 to 4.
Figure 3 shows a particular embodiment' for producing a gas
stream G according to the invention. An upper cover 13 is
provided here and the gas stream G flows between this cover
13 and the sieve belt 6 or the surface of the deposited
filament 8 in the direction of the bonding device 9. The
cover 13 is appropriately arranged parallel or
substantially parallel, to the sieve belt 6 or to the
surface of the deposited filament 8. According to a
preferred embodiment and in the exemplary embodiment
according to Fig. 3, the gas stream G flowing along the
surface of the deposited filament 8 is produced by means of
the fluid medium flowing into the bonding device 9. In
i
other words, the fluid medium flowing into the bonding
chamber 12 forms the driving force for the gas stream G.
Figure 4shows another preferred embodiment. Here air is
blown from above into the area of the secondary crimping
(area of the jumped-up deposited filament). The blown-in
gas is deflected towards the gas stream G flowing along the
surface of the deposited filament 8 by means of suitably
curved.flow baffles.14. The gas can also be sucked in here.
Appropriately and in the exemplary embodiment, the gas
stream G flows perpendicularly or substantially
perpendicularly to the direction of flow of the fluid
medium in the bonding device 9 or in the bonding chamber
1:2. According to a preferred embodiment and in the
exemplary embodiment according to the figures, only one
air-permeable sieve belt 6 is provided whereby the
deposited filament 8 is conveyed from the depositing region

7 via the region 11 and via the region of secondary
crimping (region of jumped-up deposited filament 8) into
the bonding chamber 12. The sieve belt 6 is guided in the
usual manner as a continuous belt over corresponding
deflecting rollers.
Of particular importance within the scope of the invention
is a preferred embodiment shown schematically in Fig. 1.
According to this, the unit is formed from a, cooling
chamber 3, stretching device 4 and diffuser 5 as a closed
system, apart from an air supply in the cooling chamber 3
and apart from at least one air inlet in the area of the
diffuser 5. In other words, the unit comprising the cool.ing
chamber 3 and stretching device is designed as closed apart
from the air supply in the cooling chamber 3. This closed
embodiment of the device has proved to be quite
particularly effective with regard ,to optimal nonwoven
quality and in particular in combination with the further
features according to the invention claimed here.

WE CLAIM
1. A method for producing a nonwoven from continuous filaments, wherein
filaments (1) are produced of which at least some exhibit natural
crimping,
characterized in that the filaments (1) are deposited in a depositing
region (7) of a conveying device to form a deposited filament (8) and
wherein the deposited filament (8) is conveyed with the conveying device
in the direction of a bonding device (9), and
in that a gas stream (G) flowing along in the conveying direction of the
deposited filament (8) on the surface of the deposited filament (8) is
generated.
2. The method as claimed in claim 1, wherein the filaments (1) with natural
crimping are bicomponent filaments or multicomponent filaments which
preferably exhibit a side-by-side arrangement.
3. The method as claimed in any one of claims 1 or 2, wherein a crimping of
the filaments (1) takes place after stretching the filaments (1) and before
depositing the filaments (1).
4. The method as claimed in any one of claims 1 or 3, wherein crimping of
the filaments (1) takes place after depositing the filaments (1).
5. The method as claimed in any one of claims 1 to 4, wherein the filaments
(1) are deposited on a sieve belt (6) as a conveying device or as a

component of a conveying device to form the deposited filament (8) and
wherein the deposited filament (8) is exposed to suction air in a suction
region (10) of the sieve belt (6).
6. The method as claimed in any one of claims 1 to 5, wherein the gas
stream (G) flows in the conveying direction behind the suction region (10)
past the surface of the deposited filament (8).
7. The method as claimed in any one of claims 1 to 6, wherein the flow rate
of the gas stream (G) corresponds to at least half the conveying speed of
the deposited filament (8) and preferably corresponds to at least the
conveying speed or approximately the conveying speed of the deposited
filament (8).
8. The method as claimed in any one of claims 1 to 7, wherein the deposited
filament (8) is bonded with at least one fluid medium, preferably with at
least one hot fluid medium.
9. The method as claimed in any one of claims 1 to 8, wherein the gas
stream (G) flowing along the surface of the deposited filament (8) is
generated by means of the fluid medium flowing in the bonding device
(9).
10. The method as claimed in any one of claims 1 to 9, wherein gas is blown
in and/or sucked in and is deflected by means of at least one flow guiding
device to the gas stream (G) flowing along the surface of the deposited
filament (8).
11. A device for producing a nonwoven of continuous filaments which exhibit
at least some natural crimping, comprising at least one spinning device (2)

for producing filaments (1) and comprising a conveying device with a depositing
region (7) in which the filaments (1) can be deposited to form a deposited filament
(8), wherein furthermore a bonding device (9) is provided for bonding the
filaments (1) and wherein at least one generating device is provided whereby a
gas stream (G) flowing along the surface of the deposited filament (8) in the
conveying direction of the deposited filament (8) can be generated between the
depositing region (7) and the bonding device (9).
12. The device as claimed in claim 11, wherein a stretching device (4) for stretching the
filaments (1) is arranged between the spinning device (2) and the depositing
region (7).

13. The device as claimed in one of claims 11 or 12, wherein a diffuser (5) is arranged
between the stretching device (4) and the depositing region (7).

ABSTRACT

METHOD AND DEVICE FOR PRODUCING A NONWOVEN FROM
CONTINUOUS FILAMENTS
A method for producing a nonwoven from continuous filaments is described,
wherein filaments are produced of which at least some exhibit natural crimping.
The filaments are deposited in the depositing region' of the deposited filament is
conveyed with the conveying device in the direction of a bonding device. A gas
stream (G) flowing along the surface of the deposited filament in the conveying
direction of the deposited filament is generated.

METHOD AND DEVICE FOR PRODUCING A NONWOVEN FROM CONTINUOUS FILAMENTS

Documents:

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