WO2006084987A1

WO2006084987A1 - Card and machine for the production of a non-woven fabric

Info

Publication number: WO2006084987A1
Application number: PCT/FR2006/000277
Authority: WO
Inventors: Frédéric NOELLE
Original assignee: Rieter Perfojet
Priority date: 2005-02-08
Filing date: 2006-02-07
Publication date: 2006-08-17
Also published as: FR2881758B1; FR2881758A1

Abstract

The invention relates to a carding device comprising a card (1) and a conveyor element which removes a web from the carding device. The conveyor element (4) is suitable for use in a web consolidation device (8) comprising a pressurised fluid injector.

Description

CARD AND PRODUCTION MACHINE OF A NON-WOVEN

The present invention relates to cards and machines for producing nonwovens made of natural, artificial or synthetic textile material.

The production of nonwovens from short fibers according to the techniques belonging to the dry process consists in forming one or more webs or webs of fibers by the carding technique or by the carding technique and then deposited aerially.

The webs or layers of fibers thus formed are then consolidated in a next step by the action of high-speed water jets, a technique known as consolidation by jets of water under pressure or spunlace.

In a conventional manner, the sails are collected from one or more cards and superimposed on one or more conveyor belts, generally non-porous, of great length, then the sails are transferred to the entrance mat of the consolidation machine by jets of fluid. Conventionally, the distance between the last point of delivery of the last card web and the first point of consolidation by fluid jets is several meters, of the order of 7 to 15 meters following the production lines. In a usual manner, each card produces from 1 to 3 webs of fibers which are collected and superimposed on one or more conveyor belts, then the web thus formed is transferred to a fluid jet consolidation machine.

Carding machines intended for the production of nonwovens, more generally called cardes for non-wovens, complete the carding action of the fibers by a scrambling and condensation action of the fiber webs to redirect some of the fibers into the fabric. meaning across. This jamming action has the essential effect of improving the cross-resistance characteristics of the webs and nonwovens produced from these webs.

In spite of this, it is found that the ratio of the properties of the machine direction to the direction through nonwovens produced from webs or carded webs, and in particular their resistance, is not good enough and that there is a reduction of resistance in the cross direction. The invention aims to overcome these disadvantages, while greatly simplifying the machine for producing nonwovens comprising a card.

The subject of the invention is a carding device comprising a card and a conveyor element that pulls a web out of the carding device, characterized in that the conveyor element is of a type capable of serving as a conveyor element in a carding device. veil consolidation injector of pressurized fluid jets, of the type in which the veil, conveyed by the conveyor element, passes in front of the pressurized fluid injector. It has now been understood that with the increase in production rates and the reduction of the surface masses of the fiber webs it is very difficult to maintain the ratio of the machine direction to the direction through the fiber webs until the sails or fiber webs are consolidated into a nonwoven. Since the last rolls of the card or cards until the first point of consolidation by the action of the first jets of water, the rate of condensation of the table only deteriorates by transfers between rollers and carpets and the transfers of transport mats to the following carpets. Stretches for controlling web tension and air friction at the surface of the fiber webs contribute greatly to the degradation of the cross-web properties of the carded fiber webs. This degradation is concretely translated by an increase in the strength ratio of the machine direction in the cross-direction of the nonwoven and therefore by a notable reduction of the resistance characteristics in the cross direction. By making the conveying element conveying a web out of the carding device suitable as a conjugate conveyor element of the injector of a pressurized fluid jetting device, not only is the non-woven production machine, but also considerably improves the ratio of the resistance in the machine direction to the resistance in the cross-machine direction of the nonwoven.

Carpets used according to the prior art for the transport of fiber webs are generally mats coated with rubber or a flexible synthetic material. There are also thick woven carpets made of large diameter son and having a high surface roughness for a good effect of driving the layers of fibers with a minimum of slippage. The Solid carpets are unsuitable for consolidation by water jets as they are absolutely impervious to water and air. Woven carpets are also unsuitable, because their rough structure hangs the fibers under the action of the jets of water and their too big threads mark the nonwovens even cause perforations by displacement of the fibers during the action of the jets of water. These woven carpets consist of less than 20 threads per cm in at least one of the warp or weft weave directions and consist of threads with a diameter of more than 0.40 mm. They are usually made of synthetic material, usually polyester with antistatic treatment. To achieve the invention, the carpets are chosen from fabrics having a number of son cm greater than 20 son per cm at least in a warp or weft weaving direction and, preferably, more than 30 son cm. The wires have a diameter of less than 0.40 mm and preferably less than 0.30 mm. Their permeability to air is between 2.5 m ³ / min and 30 m ³ / min and preferably between 5m ³ / min and 25 m ³ / min. They are generally made of plastic such as polyester, polyamide, or metal, such as stainless steel or bronze. Antistatic fabric treatment is not necessary because carpet moisture dissipates harmful electrostatic charges. When the collection surface of the sails is a suction drum, this drum can either be covered with a fabric identical to the conveyor fabric according to the invention, or surrounded by a conveyor which serves as a return roller, or again covered with a micro perforated shirt with small diameter holes. In the latter case, the jacket is microperforated with holes of 50 microns to 500 microns in diameter and the number of holes is between 20 and 300 holes per cm ² . This micro perforated jacket is preferably made of nickel. When the water jets are applied directly to this jacket, the distribution of the holes is preferably random. The shirt may also have openings or have reliefs to impart patterns to the nonwovens.

Since the collection surfaces of the fibers according to the invention are smoother than the fabrics of the prior art, it is recommended to use aspirations, on the one hand, for the transfer of the sails and, on the other hand , for transport to the first point of consolidation. Although not essential, the aspirations avoid the sliding of the fibers on the surface of the conveyor of transport and consolidation. The distance from the last (the most downstream) collection point of the upper sail to the first (the most upstream) point of consolidation will advantageously be less than 5 meters, preferably less than 3 meters. This distance, as short as possible given the size of the card and the consolidation device and the need to have a certain path of removal to obtain an acceptable angle of arrival of the web on the conveyor element, contributes greatly to obtaining a good quality of the non-woven fabric.

According to the invention, the fiber webs are collected at the exit of the card on the surface of a transport conveyor, preferably with the aid of suction boxes, while maintaining the structure of the web by a suction located under the conveyor. in order to avoid its elongation by friction with the ambient air and the fiber web is consolidated by the action of jets of water on the same conveyor. In certain card output configurations, the conveyor is advantageously replaced by a suction rotary drum.

The invention gives the best results when the fiber webs are transferred with a minimum of drawing from the card to the conveyor. A speed increase of less than 20%, and preferably less than 10%, is preferred between the sail speed at the exit of the card and the conveyor. For this, one or more suction boxes are used situated opposite the points of transfer of the sails on the conveyor or the drum so as to control precisely the transfer and the tension of the sails. The depression applied in the transfer boxes under the strand of the conveyor element in contact with the web is at least 10 mbar and preferably at least 30 mbar and at most 200 mbar.

At high speeds, above 100 m / min, an additional suction box firmly holds the fiber webs on the surface of the conveyor so as to avoid its elongation by friction of the air with its surface and by sliding on the surface of the conveyor .

The card can be composed essentially of a large drum and a doffer both furnished with fine toothed teeth called trimmings.

The injectors carrying out the consolidation of the sails deliver jets of water whose diameter is between 50 and 300 microns and preferably between 80 and 200 microns. The water pressure is between 5 and 300 bar and preferably between 10 and 200 bar. The invention makes it possible to minimize the transport distance between the points of delivery of the card webs and the first point of consolidation. The machine is more compact and has fewer mechanical elements, such as rollers and mats, than a machine according to the prior art. It is possible to put 2 or 3 carding devices in line on the same collector conveyor so as to superpose 4 to 6 sails to obtain the final mass of the non-woven and this at high speed, 150 m / min and more.

Fluid jets are generally used as jets of water, but jets of air or other fluids can also be used.

In the accompanying drawings, given by way of example only, FIGS. 1 to 6 are diagrams of machines for producing nonwovens according to the invention.

Figure 1: A card 1, consisting essentially of a large drum and a doffer both filled with fine teeth or teeth, delivers two fiber webs 2 and 3 on a collector conveyor 4. The sails 2 and 3 are transferred to conveyor 4 with the aid of an aspiration carried by a suction box 5. The sheet 6, consisting of the superposition of the webs 2 and 3, is kept in contact with the conveyor 5 by another suction box 7 to the first point consolidation of the web by an injector 8 delivering jets of water. The conveyor 4 consists of a polyester fabric comprising 41 threads per cm diameter 0.15 mm in the warp direction and 30 threads per cm diameter 0.20 mm in weft direction and having a permeability of 14.3 m 3 / min . A nonwoven of 40g / m2 made of 100% polyester fibers of

1, 6 dtex and length 38 mm is produced at a speed of 105 m / min. The injector 8 delivers jets of 120 microns in diameter at a pressure of 30 bars. The nonwoven has after drying a machine direction resistance of 45 N / 50 mm and a cross-directional strength of 17 N / 50 mm and a cross-machine direction resistance ratio of 2.64.

Figure 2: A card 9 delivers two fiber webs 10 and 11 to the surface of a suction rotary drum 12 around which a transport conveyor 13 is wound. A suction box inside the rotary drum 12 transfers the webs 10 and 11. Another suction box 15 firmly holds the web resulting from the superposition of the webs 10 and 1 1 to the first point of consolidation by water jets realized by an injector. The conveyor 13 is a stainless steel wire cloth made of 39 son / cm diameter 0.11 mm in the warp direction and 35 thread / cm diameter 0.14 mm in weft direction and having a permeability of 25.7 m3 / min.

FIG. 3: A card 17 delivers two fiber webs 18 and 19 on a conveyor 20. A suction box 21 transfers the webs and holds them on the surface of the conveyor up to the progressive compression point 22 of the web between the conveyor 20 and a conveyor 20. additional conveyor 23. The sheet thus compacted is wetted and slightly consolidated by an injector 24 while it is held between the conveyors 20 and 23. The jet water of the injector 24 is sucked by a suction box 25 situated opposite of the injector 24. A second injector 26 completes the consolidation performed by the injector 24. A suction box 27 draws water from the jets of the injector 26. The conveyor 20 is made of a polyester fabric comprising 41 threads per cm of diameter 0.15 mm in warp direction and 30 threads per cm of diameter of 0.20 mm in weft direction and having a permeability of 14.3 m3 / min.

A nonwoven of 30 g / m2 made of 100% viscose fibers of 1, 7 dtex and length 40 mm is produced at a speed of 160 m / min. The injector 24 delivers jets of water of 140 microns in diameter at a pressure of 15 bars and the injector 26 delivers jets of water of 120 microns in diameter at a pressure of 75 bars. The nonwoven exhibits after drying a machine resistance of 38 N / 50 mm and a cross-directional resistance of 15 N / 50 mm and a cross-machine resistance ratio of 2.53.

4: A card 28 delivers two webs of fibers 29 and 30 on a conveyor 31. A suction box 32 transfers the sails and holds them on the surface of the conveyor 31 to the progressive compression point 33 between the conveyor 31 and a drum rotary suction 34. A first injector 35 wets and consolidates the web while it is held between the conveyor 31 and the drum 34. The water of the injector 35 is sucked by a suction slot located inside the drum 34 and facing the injector 35. An injector 36 directed against the surface of the drum 34 completes the consolidation of the web. The conveyor 31 is made of polyester fabric of 25 threads per cm diameter 0.25 mm in warp and 20 threads per cm diameter 0.27 in weft and having a permeability of 22 m 3 / min. The rotating drum 34 is covered with a nickel sleeve 0.35 mm thick and having 80 holes per cm 2 diameter 400 microns. A nonwoven of 35 g / m2 consisting of 50% viscose fibers of 1, 7 dtex and 40 mm length and 50% polyester fibers of 1, 6 dtex length 38 mm is produced at a rate of 143 m / min. The injector 35 delivers jets of water 140 microns in diameter at a pressure of 10 bars. The injector 36 delivers jets of water of 120 microns in diameter at a pressure of 60 bars. The nonwoven exhibits, after drying, a machine direction strength of 49 N / 50 mm and a resistance in the cross direction of 21 N / 50 mm. The nonwoven has a cross-machine direction resistance ratio of 2.33. Figure 5: A card 37 delivers two sails 38 and 39 to the surface of a suction rotary drum 40. A suction box 41 located inside the rotary drum 40 transfers the sails to the point of compression of the sails between the drum 40 and an additional conveyor 42. An injector 43 wets and consolidates a first time the web 44 while it is held between the drum 40 and the conveyor 42. An injector 45 completes the consolidation of the first face of the web. The conveyor 42 is constituted as that of FIG.

Figure 6: A card 46 delivers two webs 47 and 48 in a web 49 on the surface of a suction rotary drum 50. A suction box 51 located inside the drum 50 transfers and holds the web 49 to the surface of the drum. to the point 52 of progressive compression of the web between the drum 50 and an additional conveyor 53. An injector 54 wets and consolidates the web. An injector 55 completes the consolidation.

The devices of Figures 1 to 6 are followed by conveyors and other consolidation cylinders by not shown water jets.

Claims

1. A carding device comprising a card (1) and a conveyor element (4) removing a web from the carding device, characterized in that the conveyor element (4) is of a type that can serve as an element ( 4) conveyor in a device (8) for consolidating the web with injector of pressurized fluid jets, of the type in which the web, transported by the conveyor element (4), passes in front of the pressurized fluid injector.

2. Apparatus according to claim 1, wherein the conveyor element is an endless belt, characterized in that the carpet comprises a fabric having a number of son cm cm greater than 20 at least in a warp or weft weaving direction, preferably greater than 30.

3. Device according to claim 2, characterized in that the son have a diameter of less than 0.40 mm, preferably less than 0.30 mm.

4. Device according to claim 2 or 3, characterized in that the permeability of the element (4) conveyor is between 2.5 m ³ / min and 30 m ³ / min.

5. Device according to one of claims 2 to 4, characterized in that the element (4) conveyor is polyester, polyamide, stainless steel or bronze.

6. Device according to claim 1, wherein the element (4) conveyor is a drum, characterized in that the drum is covered with a fabric according to one of claims 2 to 5.

7. Device according to claim 1, wherein the conveyor element is a drum, characterized in that the drum is surrounded by a perforated jacket with holes of 50 to 500 microns in diameter, preferably nickel, the distribution of holes being , preferably random.

8. Device according to one of claims 1 to 7, characterized by a suction device under the strand of the conveyor element in contact with the web.

9. Machine for producing a nonwoven, comprising a carding device and a consolidation device by fluid jets, characterized in that the carding device is as defined in the preceding claims and the veil, transported by the conveyor element, passes into the consolidation device.

10. Machine according to claim 9, characterized by a suction device facing the injector and / or under the strand of the conveyor element in contact with the web.

11. Machine according to claim 9 or 10, characterized in that the distance between the point of contact, the most downstream, of the web with the conveyor element at the point of consolidation the most upstream is less than 5 m, preferably , less than 3 m.