EP1497488A2

EP1497488A2 - Non-woven with partially joined layers and methods and machine for the production thereof

Info

Publication number: EP1497488A2
Application number: EP03746316A
Authority: EP
Inventors: Frédéric NOELLE
Original assignee: Rieter Perfojet SAS
Current assignee: Rieter Perfojet SAS
Priority date: 2002-04-12
Filing date: 2003-04-01
Publication date: 2005-01-19
Anticipated expiration: 2023-04-01
Also published as: FR2838458B1; DE60302661D1; FR2838458A1; WO2003087453A2; WO2003087453A3; EP1497488B1; DE60302661T2; AU2003249137A1; AU2003249137A8; ATE312220T1

Abstract

The machine for the production of nonwovens has a rotating cylinder (1) and a jet (2) to deliver a stream (3) of water at the cylinder. A serrated plate (4) is inserted between the jet and the cylinder, and between the two webs (5,7), to divide the water stream into a portion at the cylinder surface and a portion deflected by at least one channel downstream in the direction of cylinder rotation.

Description

Non-woven fabric with partially bound plies and its production process and machine

The present invention relates to nonwovens and their production methods and machines. More particularly, the invention relates to nonwovens comprising at least two layers of fibers or filaments which are linked together by hydraulic connection by water jets

In patent application US 2002/0039867 A1, plies are described whose longitudinal sections are heat sealed, which implies a melting of the material and, consequently, its degradation. The properties are no longer uniform. In addition, since the molten longitudinal parts do not extend continuously over the entire length, the system can only be partially filled with a product. The filling is not uniform over the length.

At the request of patent WO 93/01342, a method and a device for producing composite plies are proposed in which two elementary plies are connected to one another along a longitudinal connecting line while maintaining them, during the process of connection, spaced apart from one another by mechanical action between the connection lines during formation, by guiding an intermediate component between the plies to introduce it into the longitudinal spaces defined between the longitudinal connection lines, the means for connecting the elementary plies being needling means.

This technique has several drawbacks. It requires the use of metal needles requiring a lot of maintenance and leaving perforation marks in the nonwoven obtained. In addition, metal needles break and it is not uncommon to find pieces in nonwovens.

The invention overcomes these drawbacks. The subject of the invention is a process for producing a nonwoven, in which a first layer of fibers or filaments is passed over a mobile support, preferably over the generator of a rotating cylinder, and a second layer of fibers or filaments above the first ply between the support and an injector for projecting at least one water jet in the direction of the support, in the direction of the generator in the case of the cylinder, characterized in that the we pass the second tablecloth on a plate interposed between the support and the injector and provided, facing the generator in the case of the cylinder, with at least one solid part and at least one notch which opens out on the downstream side in the direction of passage tablecloths. The mobile support can be a conveyor but preferably it is a cylinder.

The first ply is held on the rotating cylinder which is in particular microperforated and which preferably moves at the same tangential or linear speed as the first ply. Thanks to this porous support of the microperforated cylinder or woven conveyor type which supports the fibers and reflects the water jets so as to create sufficient turbulence so that the fibers become entangled between them without them being able to escape or move indefinitely in the direction of movement of the jets, it is possible to obtain a connection between the two plies in the parts corresponding to the notches. If there were no cylinder, the inherent resistance of each layer which is minute would not allow to move the fibers and to entangle them.

As the notches which extend from one face to the other of the plate open out on the outside on the downstream side in the direction of passage of the sheets or in the direction of rotation of the cylinder, the fibers and filaments are not constrained in their movement and can thus become entangled. The process according to the invention can be applied to light nonwovens of total grammage at most equal to 80 g / m ² and of grammage less than 50 g / m ² per sheet although the process also applies to nonwovens weighing up to 200 g / m ² . The process is also well suited to the production of nonwovens made up of fibers of low titer, the titer of which is at most equal to 1.7 dtex. These are fibers which do not lend themselves well to mechanical needling by metal needles, because the fine fibers break under the action of the needles. It is not the same according to the invention where the water jets accommodate fibers of low titer. However, the invention also applies to fibers whose titer goes up to 6.6 dtex.

One can provide a jet by notch, but preferably several jets are provided by notch, in particular two or three jets, which means that the jets are aligned in rows along two or three generatrices of the cylinder or in staggered rows. The pressure of the jets is preferably understood between 30 and 400 bars. The diameter of the jets is preferably between 75 and 200 microns.

The plate interposed between the cylinder and the injector maintains, facing its solid parts, the two plies at a distance from each other while the plies bind in the notches by forming connecting bridges. The space remaining between the two plies can, after or during the operation of entanglement by passage between the cylinder and the injector, be filled with a material, in particular of threads, foam, granulate, which presents the interest in particular for hygiene products where it is thus possible to incorporate absorbent materials.

Preferably the speed of the first ply is equal to the linear speed of the cylinder.

Preferably, the second layer is also passed at the same speed as the first. These speeds are generally between 5 and 50 m / min.

According to one embodiment, hot-melt fibers are put in the sheets, and the sheets are thermally bonded by melting the hot-melt fibers, after the entanglement operation by passage between the cylinder and the injector. These hot-melt fibers, which are generally fibers called "bicomponent" polyester / polyethylene or polyester / copolyester. Their function is not to bind the layers which have already been previously linked by passage between the cylinder and the injector, but to freeze the structure obtained after said passage. One can put, for example, from 10 to 30% of hot-melt fibers, preferably distributed uniformly in the two sheets. Thanks to the method according to the invention, the plies to be bonded together are not subjected during their connection to a tensile force, since they are simply displaced and supported. The properties of the plies are improved, and in particular the properties in the machine direction are substantially the same as in the cross direction. The invention also relates to a machine for producing a nonwoven comprising a rotating cylinder and an injector sending at least one jet of water towards a generator of the cylinder, characterized by a plate interposed between the cylinder and the injector and provided, facing the generator, with at least one solid part and at least one notch through which the at least one jet of water passes and which opens out on the downstream side in the direction cylinder rotation. For the sake of simplicity, it is preferred that the plate be mounted fixed.

It is better for the notch to open to the outside along a width mouth, counted along the generatrix, equal to the greatest width of the notch, this width also being counted along the generatrix. The fibers thus have the travel necessary to move around and can become entangled.

Preferably, the plate has a thickness of between 0.5 and 15 mm so as on the one hand to be sufficiently resistant to the pressure of the water jets, but on the other hand, to be sufficiently thin so that the thickness additional that the water jet has to travel does not result in a loss of the efficiency of the water jet. Preferably, the plate is, opposite the generator, at a distance from the cylinder of between 1 and 10 mm, so that, on the one hand, the first ply can pass over the cylinder under the plate without rubbing on it. ci but also so as to reduce as much as possible the distance between the plate and the cylinder. For the same reasons, the plate is preferably, opposite the generator, at a distance from the outlet of the injector of between 2 and 40 mm. It is advantageous for the plate to have the shape of a cylindrical arc with the same center as the cylinder and with a radius just greater than that of the cylinder. The arc can have an angle at the center of 5 to 20 °. There are preferably several notches distributed uniformly or not along the generator and separated from each other respectively by solid parts which also have the same width. Each notch preferably has a dimension along the generator, therefore a width, between 1 and 50 mm. Similarly, the dimension of each solid part, along the generator, is advantageously between 2 and 500 mm. When it is desired to obtain nonwovens having a certain symmetry, it is preferred that the machine has several notches of the same dimension and several solid parts of the same dimension. But the notches on the one hand and the solid parts on the other hand can also have different widths. Preferably each solid part is oblong and its largest dimension extends perpendicular to the generator.

According to one embodiment, it is possible to superimpose two plates at a distance from each other between the cylinder and the injector and to pass between the two plates a third layer which rests on the first plate, the second layer passing between the second plate and the injector. This allows to connect three layers together. We could also consider connecting a larger number of layers in the same way.

The invention can be carried out either continuously with sails or sheets directly from a carding or spunbond type machine which are then consolidated to varying degrees by water jets (or light calendering, or mechanical sharpening) online and before the device which is the subject of this invention, either discontinuously by unwinding coils previously more or less consolidated, or by associating unwound coils with in-line formation for example when it is desired to put a layer of continuous filaments in sandwich between two layers of short fibers.

After having formed the nonwoven by the process according to the invention on a machine according to the invention, it is dried for example by hot air, the drying causing if necessary a thermal bonding of the hot-melt fibers so as to freeze the structure and make it resilient. The sheets may consist of artificial, synthetic or natural fibers or else of continuous filaments of thermoplastic or non-thermoplastic materials. The fibers and filaments are used alone or as a mixture.

The cylinder can be a rigid rotary perforated cylinder mounted outside a fixed cylindrical body and an internal diameter adjusted to the external diameter of the cylindrical body so that the minimum clearance thus preserved allows rotation while minimizing air leaks. This rotary cylinder can be a simple perforated sheet, a bronze or stainless steel cylinder pierced with holes arranged in a helix, a honeycomb cylinder. It can also be a tube of rolled perforated sheet coated with a drainage sleeve made of coarse metallic fabric which ensures good uniformity of water extraction. This rotary cylinder can support a thinner perforated sleeve, which effectively supports the filaments and fibers of the nonwoven during hydraulic entanglement. The distribution of the holes in the sleeve can be random. The holes can also be organized by being aligned or staggered. The holes of the sleeve can also be distributed in small ordered perforation zones distributed randomly on the surface of the sleeve. The sleeve can be made of a metallic fabric or synthetic material or a mixture of metallic fabric and synthetic material. It is preferred that the diameter of the holes in the sleeve is between 50 and 500 μ. The sleeve preferably has a thickness of between 0.1 and 0.6 mm. The inside of the cylinder communicates with an air and water extraction pipe.

The invention finally relates to a nonwoven comprising at least two layers of fibers or filaments, bonded only on longitudinal parts of them. According to the invention, the nonwoven is free from mechanical needling perforations. The nonwoven is also free of binder, even when hot-melt fibers are used, since these are only intended to freeze the structure obtained after passing through the machine according to the invention, and not to obtain a bond between the tablecloths as evidenced by the fact that the melted hot-melt fibers are both in the parts of the tablecloths which are not linked and in those which are. The nonwoven has longitudinal connecting portions, which are continuous extending over the entire length of the nonwoven, without interruption. When it has hot-melt fibers, these do not represent in the parts which are bound less than 20% by weight and better still less than 10% by weight.

This nonwoven has between the longitudinal fiber bridges continuous longitudinal spaces which are either left empty to give volume, or filled with thread, foam or granulate. The volume or filling is large and uniform. It is also possible to use the air trapped in the spaces between the decks to give the nonwoven better insulating power. The nonwovens can have a grammage of less than 80 g / m ² although it is also possible to produce nonwovens having a grammage of up to for example 200 g / m ² . It is also possible to use fibers of low titer, for example of 1.7 dtex and less. The nonwoven according to the invention preferably has a thickness of the linked parts between 0.3 and 3 and a thickness of the non-linked parts between 0.5 and 15 mm.

The nonwoven can be used in the field of hygiene with for example a filling of the free spaces between the sheets with super absorbent products or with microcapsules. The nonwoven can also be used as insulation material. It can also constitute excellent filters when the free spaces between the layers are filled with activated carbon. The nonwoven can also be used as a household or professional wiping cloth. It is perfectly suited to so-called electrostatic cloths for wiping dust.

In the accompanying drawings, given solely by way of example: FIG. 1 is a diagrammatic side view in elevation of a machine according to the invention, FIG. 2 is a view similar to FIG. 1, of a variant of machine according to the invention, FIGS. 3 to 9 are perspective views of plates used in the machine according to the invention, FIG. 10 is a schematic sectional view of a machine according to the invention while plies pass through it, and FIGS. 11 and 12 are schematic sectional views of nonwovens according to the invention.

The machine shown in FIG. 1 comprises a cylinder 1 of conventional horizontal x axis of hydraulic nonwoven binding machine. Above the cylinder 1 is mounted on a frame, which is not shown, a fixed injector 2 which sends a row of jets 3 of pressurized water, each jet being vertical, and the row extending along the generator the highest of the cylinder 1. A plate 4 is fixedly mounted on the frame of the machine and is interposed between the cylinder 1 and the injector 2 while being at a distance from one and the other. A first ply 5 unwinds from a reel 6 and passes in the interval between the cylinder 1 and the plate 4. A second ply 7 unwinds from a reel 8 and passes after returning to a return roller 9 in the 'interval between the plate 4 and the injector 2. The cylinder 1 is rotated in the direction of arrow F which symbolizes rotational drive means. The two layers 5 and 7 which are linked by the action of the row of water jets 3 exit downstream of the cylinder 1 on a return roller 10. In Figure 2, there are two plates 11, 12 in the gap between the cylinder 1 and the injector 2, and in addition to the plies 5 and 7, there is provided a ply 13 unwound from a coil 14 which passes on a return roller 16 before going between the two plates 11 and 12 while being in contact with the upper face of the plate 12. The three layers are linked to the outlet of the cylinder 1 and pass together on the roller 10.

FIG. 3 represents one of the plates 4, 11 or 12. It is a steel plate having the shape of a comb with five teeth 17 coming from a core 18 and having four notches 19 passing through on the in part .. The comb is mounted in the machines of Figures 1 and 2, so that the notches 19 open outwardly from the downstream side in the direction F of rotation of the cylinder 1. The notches are rectangular. Their long side is parallel to the direction of passage of the plies 5, 7 13. Their short side is perpendicular to this direction and therefore parallel to the generator of the cylinder along which the row of jets 3 is arranged.

In FIG. 4, the comb comprises a core 20 from which five teeth 21 come which define notches 22 in the shape of a triangle with a point pointing towards the core 20. The open side of the triangles is directed on the downstream side of the cylinder 1.

In Figure 5, the teeth 23 of the comb are rectangular and have the same dimension but are at different distances from each other so that there is created there notches 24, 25 of different widths, as counted according to the generator of cylinder 1, that is to say parallel to the largest dimension of the comb core.

In Figure 6, the comb has five teeth 26 separated from each other by notches with rounded bottom 27. In FIG. 7, the teeth 28, 29 are rectangular but have different widths, just as the notches 30, 31 have different widths.

In FIG. 8, the upper face of the comb is not flat, unlike the combs of FIGS. 3 to 7, but is wavy in a frame corresponding to the distance between the teeth 32 whose upper faces are semi-cylindrical.

In FIG. 9, the comb has an upper face 33 and a lower curved face 34. The radius of the face 34 is just greater than the radius of the cylinder 1.

We recognize in Figure 10 the injector 2, the first layer 5 and the second layer 7 separated by teeth 17 of the comb and the surface of the cylinder 1. The injector sends a row 3 of jets in the notches. There are several jets in each notch.

Nonwovens are thus obtained, as shown in FIG. 11, which comprise the first ply 5 and the second ply 7 having bridges 35 continuous longitudinally entangled with the fiber. It is defined between the layers 5 and 7 and their bridge 35 of the free spaces 36 which are longitudinally continuous. Figure 11 corresponds to the case where the thickness of the plate 4 is relatively large and the width of the notch 19 is relatively large. On the other hand, in FIG. 12, the thickness of the plate 4 has been chosen to be smaller and the width of the notch 19 has been narrower. We symbolized by a line 36 and lines 37 the presence of hot-melt fibers. In addition, one of the spaces was lined with microcapsules. The following examples illustrate the invention.

Example 1:

A carded tablecloth of 35 g / m2 composed of a mixture of 70% viscose 1.7 dtex / 40 mm and 30% polyester 1.7 dtex / 38 mm is consolidated by hydraulic entanglement on a JETLACE 3000 installation marketed by Rieter Perfojet company at a pressure of 50 bars and a speed of 40m / min. Two identical rolls of this viscose / polyester blend are produced. The two rollers are placed on a machine according to the invention in which the indented plate has a thickness of 2 mm and has indentations of 6 mm in width separated by solid parts of 4 mm in width. The two plies are assembled by hydraulic entanglement at a speed of 15m / min according to the invention by an injector delivering jets of 120 microns in diameter at a pressure of 100 bars. The jets are arranged in groups of 7 jets in front of each notch, each group having a width of 3.7 mm and the inter-axis from group to group is 10 mm. In each group the jets are arranged in staggered rows in two rows. A nonwoven structure is thus obtained having a large volume, a thickness of 2.5 mm, with a succession of zones of interlinking of the two layers and of bulky zones without interlinking of the layers forming cavities. The attachment or bonding of the two sheets is excellent and they cannot be separated from each other without destroying the nonwoven.

Example 2:

A carded tablecloth of 60 g / m2 made of 100% polyester fibers of

1.7 dtex / 38 mm is consolidated by hydraulic entanglement on a JETLACE 3000 installation marketed by the company Rieter Perfojet at a pressure of 60 bars and at a speed of 25m / min. Another sheet of 50 g / m2 of continuous polypropylene filaments of 1.8 dtex is formed on a PERFOBOND 3000 installation from the company Rieter Perfojet and then consolidated by hydraulic entanglement on a JETLACE 3000 installation marketed by the company Rieter Perfojet at a pressure of 100 bars and at a speed of 25m / min. The two rollers are placed on a machine according to the invention in which the plate notched to a thickness of 2 mm and has notches 4 mm wide separated by solid parts 4 mm wide. The consolidated web of continuous filaments is placed below the scalloped plate, that is to say between the latter and the rotary cylinder, while the consolidated web of polyester fibers is placed above the scalloped plate between this and the injector delivering the water jets. The two plies are assembled by hydraulic entanglement at a speed of 25 m / minute by an injector delivering the jets of 120 microns in diameter at a pressure of 150 bars. The jets are arranged in groups of 5 jets opposite each notch, each group having a width of 2.6 mm, the inter-axis between the groups of jets being 8 mm. In each group the jets are arranged in staggered rows in two rows. A bulky nonwoven structure is obtained and having a succession of bulky zones trapping a large amount of air and separated by connecting zones between the sheets. The sheets do not separate, the resistance to delamination is excellent, the nonwoven has a thickness of 3 mm in the unbound parts.

Example 3: A carded tablecloth of 35 g / m2 composed of 80% of polyester fibers of 1.7 dtex / 38 mm and of 20% bicomponent fibers Celbond from the company Kosa of 3.3 dtex and of length 38 mm is consolidated by hydraulic entanglement on a JETLACE 3000 installation marketed by the company Rieter Perfojet at a pressure of 40 bars and at a speed of 30 m / min. Another carded tablecloth of 40 g / m2 composed of 100% polyester fibers of 1.7 dtex / 38 mm is consolidated by hydraulic entanglement on a JETLACE 3000 installation marketed by the company Rieter Perfojet at a pressure of 50 bars and at a speed of 30m / min. The two plies are placed on a machine according to the invention in which the scalloped plate has a thickness of 2 mm and has scallops of 6 mm in width separated by solid parts of 4 mm in width. The consolidated tablecloth in 100% polyester is placed below the notched plate, that is to say between it and the rotary cylinder, while the consolidated tablecloth composed of the mixture of polyester and component fibers is placed at the - above the plate notched between it and the injector delivering the water jets. The two plies are assembled by hydraulic entanglement at a speed of 25 m / minute by an injector delivering jets of 120 microns in diameter at a pressure of 100 bars. The jets are arranged in groups of 7 jets in front of each notch, each group having a width of 3.7 mm, the axis between the groups of jets being 10 mm. After the treatment of the two sheets by hydraulic entanglement, the sheet is dried at a temperature of 125 to 130 ° C in an oven which has the effect of melting the polyethylene part of the bicomponent fibers. A bulky nonwoven structure is obtained and having a succession of bulky zones trapping a large amount of air and separated by connecting zones between the sheets. The nonwoven thus obtained has excellent resilience of the raised parts.

Example 4:

A carded sheet of 30 g / m2 made of 100% polyester 1.7 dtex / 38 mm is consolidated by hydraulic entanglement on a JETLACE 3000 installation sold by the company Rieter Perfojet at a pressure of 40 bars and at a speed of 30m / min. Two rolls of this polyester sheet consolidated by hydraulic entanglement are prepared. Another sheet of 30 g / m2 of continuous polypropylene filaments of 1.8 dtex is formed on a PERFOBOND 3000 installation from the company Rieter Perfojet and then consolidated by hydraulic entanglement on a JETLACE 3000 installation marketed by the company Rieter Perfojet at a pressure of 70 bars and at a speed of 30m / min. The three rollers are placed on a machine according to the invention which comprises two scalloped plates superimposed so that the scallops are aligned vertically, that is to say in the axis of the jets. The plates are spaced from each other by 2 mm. The notched plates have a thickness of 1.0 mm and have notches of 6 mm in width separated by solid parts of 4 mm in width. The polyester sheets are placed respectively for one below the lower plate against the cylinder and for the other above the upper plate facing the injector. The sheet of polypropylene continuous filaments is unwound between the two plates. The three layers are assembled by hydraulic entanglement at a speed of 10 m / min according to the invention by an injector delivering jets of 120 microns in diameter at a pressure of 125 bars. The jets are arranged in groups of 7 jets in front of each notch, each group having a width of 3.7 mm and the interaxis from group to group is 10 mm. In each group the jets are arranged in staggered rows in two rows. A non-woven structure is thus obtained in three layers having a large volume and a maximum thickness of 5 mm, with a succession of zones of interlinking of the two plies and of bulky zones without interlinking of the plies forming cavities. The attachment or bonding of the three layers is excellent and they cannot be separated from each other without destroying the nonwoven.

Claims

1. A method of producing a nonwoven, in which a first layer of fibers or filaments is passed over a movable support, preferably over the generator of a rotating cylinder, and a second layer of fibers or filaments to the above the first layer between the support and an injector for projecting at least one jet of water in the direction of the support, preferably in the direction of the generator in the case of the cylinder, characterized in that one passes the second ply on a plate interposed between the support and the injector and provided, facing the generator in the case of the cylinder, with at least one solid part and at least one notch through which passes at least one jet and which opens to the outside on the downstream side in the direction of passage of the sheets.

2. Method according to claim 1, characterized in that the speed of the first ply is equal to the linear speed of the cylinder.

3. Method according to claim 1 or 2, characterized in that one puts hot-melt fibers in the sheets which are thermally bonded by melting the hot-melt fibers after the entanglement operation by passage between the cylinder and the 'injector.

4. Method according to claim 1, 2 or 3, characterized in that at least one space remaining between the two plies is filled with a material after or during the entanglement operation by passage between the cylinder and the injector.

5. Machine for producing a nonwoven comprising a rotating cylinder (1) and an injector (2) sending at least one jet (3) of water towards a generator of the cylinder (1), characterized by a plate (4) interposed between the cylinder (1) and the injector (2) and provided, facing the generator, with at least one solid part and at least one notch through which passes at least one jet (3) of water and which opens outside on the downstream side in the direction of rotation of the cylinder (1).

6. Machine according to claim 5, characterized in that the plate (4) is mounted fixed.

7. Machine according to claim 5 and 6, characterized in that the notch opens to the outside along a width mouth, counted down along the generator, equal to the greatest width of the notch.

8. Machine according to claim 6 or 7, characterized in that the plate (4) has a thickness between 0.5 and 15 mm.

9. Machine according to one of claims 5 to 8, characterized in that the plate (4) is, opposite the generator, at a distance from the cylinder between 1 and 10 mm.

10. Machine according to one of claims 5 to 9, characterized in that the plate (4) is, opposite the generator, at a distance from the outlet of the injector (2) between 2 and 40 mm.

11. Machine according to one of claims 5 to 10, characterized in that the plate has the shape of a cylindrical arc with the same center as the cylinder and a radius just greater than that of the cylinder.

12. Machine according to one of claims 5 to 11, characterized in that the dimension of at least one notch along the generator is between 1 and 50 mm.

13. Machine according to one of claims 5 to 12, characterized in that the dimension of at least one solid part along the generator is between 2 and 500 mm.

14. Machine according to one of claims 5 to 13, characterized by several notches preferably of the same dimension.

15. Machine according to one of claims 5 to 14, characterized by several solid parts, preferably of the same size.

16. Machine according to one of claims 5 to 15, characterized in that at least one solid part is oblong and its largest dimension extends perpendicular to the generator.

17. Nonwoven comprising at least two layers of fibers or filaments bonded together only on longitudinal parts of them, which are continuous and which are essentially not melted, characterized in that it is free from perforations mechanical needling.

18. A nonwoven according to claim 17, characterized in that the grammage of the nonwoven is at most equal to 80 g / m ² .

19. The nonwoven according to claim 17 or 18, characterized in that the fibers or filaments have a titer at most equal to 1.7 dtex.

20. Nonwoven according to one of claims 17 to 19, characterized by an added material interposed between the two plies in the parts of the plies which are not linked.

21. Nonwoven according to one of claims 17 to 20, characterized in that it comprises hot-melt fibers melted both in the parts of the sheets which are not linked and in those which are.