FR2911616A1 - Plant for producing non-woven fibrous sheet, comprises first fluid-permeable moving element, second moving element and device for projecting jet through which first element moves - Google Patents

Abstract

In a plant for producing a fiber- and/or filament-based sheet, comprising a first fluid-permeable moving element (1) displaced in one direction, a second moving element (2) and fluid jet projecting device (3), the first element moves (in the direction of the projected jets) between the jet projector and the second element at the point of projection of the jets onto the first element. Independent claims are included for: (1) a corresponding sheet production method, involving producing an assembly of fibers and/or filaments which can be defibrillated by a liquid jet on a fluid-permeable moving element, where the assembly is defibrillated by a fluid jet in such a way that fibers and/or filaments are projected onto a second moving element, on which they form a sheet; and (2) a non-woven having long fibers or filaments and short fibers (the length ratio of the long and short fibers being more than 10), where both the long and short fibers are present at all locations on the non-woven.

Description

The present invention relates to a novel method of forming

  sails, sheets, tablecloths or ribbons by fiber spraying for the production of nonwovens.

  For the production of nonwovens, there is already at least one method of forming sheets, webs or webs by spraying fibers. It is known in the so-called airlay dry-forming technique to defibrate, by means of a rotating drum provided with fine teeth, a continuously fed sheet of fibers, and to project these fibers against another rotating drum or carpet to form a web or a veil of fibers. This projection technique is for example marketed by the American company Rando under the brand Rando Webber. Other machines more advanced and also using the principle of fiber projection by a drum lined with fine teeth, such as the Turbo Card of the German company Spinnbau or Air Web of the French company Thibeau are also proposed.

  These machines have been in existence for decades and are appreciated for their ability to produce nonwovens having a ratio of the tensile strength properties in the machine direction very close to the tensile properties in the transverse direction. Nevertheless, they are not very successful because they are limited in productivity by the maximum amount of fibers that a same rotating drum can project in a uniform and continuous manner. In general, and in the field of the production of nonwovens of less than 80 g / m2, the maximum productivity is of the order of 200 kg / h per meter of machine leveling, whereas conventional cards for non -tissés have productivities of 250 or even 300 kg / h per meter of production width. In addition, the uniformity of fiber distribution is much lower than that achieved with conventional cards at comparable productivities and weights per square meter.

  Current machines are adapted to a type of fiber. For example, machines designed for paper-type fibers, that is to say fibers of: Pea mixed with other fibers less than 15 mm in length, are not suitable for the formation of fiber webs. 40 mm long textiles. Conversely, machines of the Air Web or Turbo Card type developed for cotton and textile fibers are not suitable for very short fibers such as wood fibers mixed with synthetic fibers.

  No fiber projection web forming machine is suitable for artificial and synthetic continuous filaments.

  The new method of projection formation overcomes the disadvantages of known methods. The same machine is suitable for all types of fibers, natural, artificial or synthetic fibers and artificial or synthetic continuous filaments. It allows, in a single jet, to project at the same time fibers of very different length, having an average length ratio of long fibers compared to short fibers of 10 or even 15 and more. It is a universal jet spray method of forming web in terms of the type of fibers that can be used. It is also universal in terms of mass per square meter of sail or sheet formed, from less than 10 g / m2 to more than 500 g / m2, and this at high productivity, 300 kg / h and per meter of jet and more. It also makes it possible to form webs having ratios of the resistance in the machine direction to the resistance in the very wide transverse direction of 1 to 10 on the same machine.

  The new training method is firstly to divide the process of forming a sheet, web or web into two steps.

  In the first step, an assembly of fibers and / or filaments held together so that they can be defibrated by a jet of liquid on a first movable member through which fluid can pass is produced. The first step is to form an even and unconsolidated layer, without melting points, fibers, or even multiple layers of fibers superimposed by one or more of the known forming techniques. This can be for example one or more machines dry, wet or molten, such as for example cards, cards followed by lappers, cards followed by lappers and stretchers, paper-type head boxes, foam headboxes, spunbond towers and any other known training device. The layer or layers of fibers deposited on the first movable element must be able to defibrate under the action of the jet. Tablecloths or leaves that have undergone strong consolidation should be avoided. Good results are obtained with webs or webs of fibers having a breaking length of less than 50 m. This is the free length for which the breaking of the web is obtained when it is subjected only to the action of its own weight. The EDANA ERT 20.2-89 standard gives an accurate method for calculating the breaking length from the value measured with a dynamometer of the tensile strength of the sheet. However the use of a dynamometer is not always possible given the poor cohesion of some layers. In the case of wet-laid sheets, their breaking length is evaluated when they are impregnated with at least 300% water by weight. The regular layer of fibers formed in the first stage is preferably continuously deposited on a movable member which directs it to the second stage. The second step consists in defibrating with a jet of fluid, preferably a jet of water, the regular layer disposed on the first movable element, and at the same time as the defibering, in projecting with the same jet of fluid the fibers against a second movable element disposed opposite the first movable element at the injection zone of the fluid jet. The fibers are deposited on the surface of the second movable element in a regular layer. The invention also relates to a plant for producing a web based on fibers and / or filaments, comprising a first element movable in a direction of displacement and through which fluid can pass, a second mobile element and a fluid jet projection device, characterized in that the first movable element is, considered in the direction of the jets of the projection device, interposed between the projection device and the second mobile element at the jets projection point 30 on the first mobile element. The first movable member is preferably a woven conveyor, permeable to air, water and gases. And the jet of fluid is injected through the first movable element. The first movable element is preferably a conveyor made of a synthetic or metallic fabric. It preferably has a permeability of between 100 and 1400 CFM, and preferably between 200 and 800 CFM. When it is a fabric, it consists of synthetic or metallic threads, 0.1 mm in diameter and preferably between 0.10 and 0.6 mm in diameter. The fabric consists of 2 to 60 threads per cm in warp and weft direction, and preferably 10 to 40 threads per cm in warp and weft direction. The fabric may be a single layer or multilayer fabric. In multilayer fabrics, generally two or three layer fabrics are found. The first movable element may also be a thin microperforated metal or synthetic sheet, supported or not by a rigid and permeable structure such as a rotary drum. In the preferred embodiment of the invention, a fiber retaining device, for example by vacuum suction through a suction slot, is arranged behind the first movable element and immediately upstream of the projection zone of the fluid. Preferably, the fiber retainer is disposed on the same side of the first movable member as the fluid jet ejection device. In a preferred embodiment of the invention, a mechanical compression device of the fiber web is disposed upstream of the jet point of the jet of fluid. Preferably, the device for mechanically compressing the web comprises means for wetting the web, for example an injector delivering jets of water. Preferably, the device for compressing and wetting the sheet is chosen from known devices and used for the production of non-woven fabrics consolidated by jets of water, such as those proposed by the company Rieter Perfojet - France.

  The jet of fluid can be homogeneous over the entire useful width, as for example in the case of a thin blade of water, but it can also be generated by one or more rows of close jets, such as jets of water. cylindrical water from an injector such as those used in the technique of consolidation by water jets and delivering from 100 to 5000 jets per meter, diameter of 50 to 1000 microns and preferably between 80 and 400 microns. The jet of fluid may also consist of divergent water jets, such as jets from jet nozzles. In this case, the jets intersect to ensure the continuity of the jet over the width of the machine. The fluid jets or jets are preferably jets of liquid such as jets of water, it can also be jets of solvent, steam jets, jets of air or gas jets. It can also be a combination of different fluids. The shape and the density of jets can also vary according to the transverse direction of the machine in number of jets, in diameter and in density of the jets, for example to form nonwovens having bands of appearance and of different structure in the machine direction. The second movable element may be of the same type as the first or different. This may for example be a rotating drum is covered with a metal or plastic fabric or covered with the micro-perforated sleeve and flat surface. It may be a drum presenting openings with or without a sub-canvas. It may also be a drum or carpet having geometric patterns in relief and / or hollow to produce patterned nonwovens or whose surface has areas of different shapes, relief and / or density. The second movable element may be a microperforated drum whose surface is bristling with reliefs for producing nonwovens having apertures or perforations in the direction of the thickness. In a preferred embodiment, the first movable member is an endless mat consisting of a polyester yarn fabric, and the second movable member is a rotating drum covered with a micro-perforated nickel sleeve as employed by the Company. Rieter Perfojet for the production of nonwovens by entanglement by jets of water. In a preferred embodiment of the invention, a suction device is disposed behind the second movable member, at the fiber receiving zone, for collecting and discharging fluid from the jet of fluid that has projected the fibers onto the second mobile element. The suction is carried out inside the drum and the evacuation of the fluid is from the rear. The fluid can be filtered and recycled. The speed of the second movable member may be greater than the speed of the first movable member. In this case, the mass per square meter of the nonwoven obtained will be less than that of the web or sheets superimposed on the first movable member. The velocity of the second movable member may be less than the velocity of the first movable member, in which case the mass per square meter of the nonwoven obtained will be greater than the mass per square meter of the fibers present on the first movable member. The speeds of the first and second movable elements may be identical. The optionally adjustable speed of the first and second movable element is between 1 and 2000 n./min. The ratio of the speed of the second movable element to the first movable element and between 0.01 and 100 and preferably between 0.1 and 10.

  The direction of movement of the fibers on the second movable element may be the same as on the first movable element or in the opposite direction. A displacement: in the opposite direction allows a reorientation of the fibers particularly interesting when one wants to obtain a good reorientation of the fibers in the transverse direction, with starting fibers preferentially oriented in the machine direction.

  The movement of the fibers on the second movable member may be in a direction not parallel to the first movable member. The direction of movement of the second movable element may for example make an angle of 5 to 90 with the direction of movement of the first movable element.

  It is also possible to have two or more devices according to the invention, one after the other in the direction of travel of the fibers. In this case, the second movable element of the first device becomes the first movable element of the second device and a new jet of fluid is injected through the second mobile element to project the fibers onto a third mobile element. And so on. The directions of movement may vary from the first to the second movable element, from the second to the third and so on. The directions of movement can also vary from one element to the next.

  The distance between the first movable element and the second movable element depends on the thickness of the fiber web present on the first movable element and the fluid used for the jet. It also depends on the power of the jet. In general, the greater the distance, the wider the area of removal of the fibers on the second movable member. The fiber mixture is improved by a large distance. The distance from the first mobile element to the second mobile element at the point of injection of the fluid is generally between 2 and 500 mm, and preferably between 5 and 200 mm.

  The distance between the two movable elements is adjustable for example by a means of displacement of one relative to the other.

  When the production of composite nonwovens made of fibers and other layers such as continuous filament layers or fabrics or knits or other nonwovens is desired, it is particularly advantageous to project the fibers of the first movable member on the second movable member when the latter is covered with one or more layers of textile material such as fabric or continuous filaments. When they are continuous filaments, this layer or layers of continuous filaments can be previously consolidated by spot melting or by other methods, it can also be simply compacted with little cohesion, or can be deposited without cohesion at all. filaments being totally free. It can also be a non-woven spunbond or a composite with meltblown which has been treated with water jets to soften or perforate it before the projection of the other components on its surface and its thickness.

  After the step of forming the nonwoven by projection of the fibrous component (s) on the second mobile element by the fluid jets or jets, the substrate can either be used as it is or undergo a complementary mechanical consolidation by jets of fluid, either by another mechanical process such as compression, needling, or by melting one of the components by spot or smooth roll calendering, or by melting one of the components in a through-air oven, or again by the addition of chemical binders. This list of consolidation techniques is not limiting and all the consolidation techniques can be used either directly on the second mobile element or downstream thereof. It is also planned to perform finishing, coating, perforation, rolling with other non-woven after the formation of the non-woven and or consolidation.

  In the case of consolidation by water jets, the first injectors are preferably installed facing the second mobile element supporting the fibers, that is to say on him. The jets have diameters between 80 and 200 microns and there are 500 to 5000 jets per meter of machine width. The water pressure is between 20 bar and 400 bar, and preferably between 30 bar and 250 bar. If necessary, it is also planned to carry out additional consolidation steps of the same type or different. For example, the non-dried product may be dried in a through-air oven and then calendered hot to give it resistance or aesthetic reasons. The drying is carried out at temperatures of preferably between 80 ° C. and 250 ° C.

  The invention finally relates to a nonwoven having long fibers or filaments and short fibers, the average ratio of the length of the long fibers to the short fibers being greater than 10, characterized in that there are both long fibers and short fibers in any non-woven location.

  Figures 1 to 3 are diagrams of facilities according to the invention.

  DESCRIPTION OF FIG. 1 The first movable element 1 is arranged opposite a second movable element 2. A fluid ejection device 3 in a jet is disposed behind the first movable element 1. A suction device 4 is arranged behind the second movable element and facing the ejection zone of the fluid through the first movable element. The unconsolidated sheet of fibers or filaments from a not shown forming machine advances on the first movable member 1 and the fibers 6 constituting the sheet 5 are projected onto the surface of the second movable member 2 in the region. ejection of the fluid. A new ply of fibers 8 is thus formed. It differs from the web 5 by the orientation of its fibers, possibly its mass per square meter if the speed of the first movable element differs from the speed of the second movable element. It also differs from the sheet 5 by the degree of mixing of its constituent fibers if there are several or if there were several constituent layers in the sheet 5.

  The double arrow F symbolizes the means of movement of the sky elements 1 and 2 relative to each other so as to modify the distance between the upper strand of the element 1 and the lower strand of the element 2, which are opposite.

  Description of Figure 2 A fiber web 9 advances on a first movable member 10. it is first compressed by a compression device 11 conveyor. Then it is wetted by an injector 12 delivering streams of water 13. A device 14 consisting of a suction box terminated by a slot 15 holds the fibers of the sheet 9 immediately before the fluid ejection device 16. The fibers are projected by the jet of water 18 on the surface of a drum 19 covered with a microperforated sleeve such as those used in the consolidation of nonwovens by jets of water. A suction 20 disposed inside the drum 19 discharges a portion of the jet water. Two injectors 21 delivering jets of water consolidate the nonwoven 22 by the known technique of consolidation by jets of water. A suction roll 23 expresses a portion of the water contained in the nonwoven and then it is dried in a not shown through air oven.

  Description of Figure 3 The installation of Figure 1 is completed by the fact that it is provided on the upper run of the conveyor 2, which is permeable to a jet of water, a device 24 for jetting water jets which defibers the web 8 and projects the fibers 25, with the aid of a suction device 26 on a conveyor 27. The fibers form a new web 28. At the location of the water spray device 24, the web 8 advances from the right to the left while at the same location and downstream from it on the conveyor 27, the web 28 advances from the left. to the right.

  Examples For carrying out the examples, an installation according to the invention and of the type of that described in FIG. 2 is used. The first movable member is made of 800 CFM polyester permeability polyester fabric having 22 yarns per cm in a 0.25 mm diameter warp direction and having 17.5 yarns per cm in a weft direction of diameter 0, 27 mm. A fiber holding device is disposed under the first movable member and consists of a suction slot of width 10 mm and having an adjustable depression of -10 mbar to -80 mbar. Immediately downstream of the holding device and in the direction of displacement of the fibers, an injector delivers a single row of water jets. There are 2000 jets of water per meter of machine width. The jets have a diameter of 120 microns. The jets simultaneously defibrate and continuously project the fibers of the first movable element to the surface of a second movable element disposed facing the first movable element at the jet injection point which is also the point of projection of the fibers. The second movable element is a rotating drum covered with a microperforated sleeve with holes 300 microns in diameter and before 100 holes per cm 2 of surface. A depression of -80 mbar is applied inside the microperforated sleeve and over a width of 25 mm facing the projection zone of the fibers of the first movable element. Opposite the second mobile element are arranged after the receiving area of the projected fibers, two water jet consolidation injectors of the same type as those used for the consolidation of nonwovens by the so-called Spunlace technique. They deliver 1666 jets per meter. The jets have a diameter of 120 microns. Suction slots in which a vacuum of -80 mbar is applied are arranged facing each injector inside the rotary drum.

  Example 1 Two webs of a blend of 50% viscose fiber and 50% polyester fiber of 30 g / m 2 each were produced in-line at 166 m / min with two conventional card-type cards for nonwovens. three combers. The viscose fibers have a length of 40 mm and a pull of 1.7 dtex. The polyester fibers have a length of 38 mm and a title of 1.7 dtex. The two walls of 30 g / m2 are superimposed in a 60 g / m2 web and the web of 60 g / m2 is continuously deposited at the speed of 166 m / min on the first mobile element. The depression in the holding device is -30 mbar. The pressure in the projection injector is 30 bar. The second movable element has a speed of 250 m / min. The consolidation injectors on the second mobile element have pressures of respectively 60 bar and 100 bar. The nonwoven thus formed and consolidated is dried in a through air oven at a temperature of 130 C. It is uniform and resistant. It has a mass per square meter of 40 g / m2. It was produced at 250 m / min. This is a speed 50% higher than the maximum speed that the same two cards can achieve with this mixture of fibers and a total mass per unit area of 40 g / m2 or 20 g / m2 per card.

  EXAMPLE 2 Example 1 is repeated. Two carded veils of 15 g / m 2 each are produced. With an airlaid type machine, a layer of wood fibers of 3 mm average length and 35 g / m2 is deposited between the two carded webs of 15 g / m2. The three superposed layers of fibers are deposited at a speed of 100 m / min on the first movable element. The depression of the holding device is -40 mbar. The formation jet has a pressure of 30 bar. The speed of the second moving element is 100 m / min. The pressure of the injectors facing the second movable element and respectively 40 bar and 70 bar. The nonwoven thus formed and consolidated is dried in a through air oven at a temperature of 150 C. It is uniform and resistant. The wood fibers are mixed with the fibers of the carded veils. The nonwoven obtained has a mass per square meter of 63 g / m2. A small proportion of very short wood fibers was washed away by the water flow, which explains the loss of mass per square meter between the inlet and the outlet.

  Example 3 Example 2 is repeated with a speed of the second moving element of 160 m / min. The nonwoven is uniform and resistant. The wood fibers are mixed with the fibers of the carded veils. The nonwoven obtained has a mass per square meter of 39 g / m2.

  Example 4 Example 2 is repeated with a speed of the second movable element of 40 m / min. The nonwoven is uniform and resistant. The wood fibers are mixed with the fibers of the carded veils. The nonwoven obtained has a mass per square meter of 161 g / m2.

  EXAMPLE 5 Example 2 is repeated, replacing the upper carded web, that is to say the one that is above the wood fibers, with a ply of 15 g / m 2 of 1.8 continuous polypropylene filaments. dtex from a spunbond tower. The nonwoven obtained is uniform and resistant. The wood fibers are mixed with the fibers of the carded fleece as well as with the continuous filaments. The nonwoven obtained has a mass per square meter of 63 g / m2.

  Example 6 Example 5 is repeated with a speed of the second movable element of 130 m / min. The nonwoven is uniform and resistant. The nonwoven obtained is uniform and resistant.

  The wood fibers were mixed with the fibers of the carded fleece as well as with the continuous filaments. The nonwoven obtained has a mass per square meter of 48 g / m2.

Claims (21)

  Apparatus for producing a fiber-based and / or filament-based web, comprising: a first member (1) movable in a direction of travel and through which fluid may pass; a second (2) movable member; a device (3) for projecting a jet of fluid, characterized in that the first movable element (1) is, considered in the direction of the jets of the projection device, interposed between the projection device (3) and the second element ( 2) mobile at the point of projection of the jets on the first element (1) mobile.   2. Installation according to claim 1, characterized in that the first movable element is a conveyor or drum which is woven or microperforated.   3. Installation according to claim 1 or 2, characterized by a device for retaining a web on the first movable element arranged upstream, in the direction of movement of the first movable element, the projection device.   4. Installation according to one of claims 1 to 3, characterized by a mechanical compression device upstream, in the direction of movement of the first movable member, the projection device.   5. Installation according to claim 4, characterized in that the compression device comprises a wetting means.   6. Installation according to one of the preceding claims, characterized in that the projection device gives jets of variable shape and / or a number c.e jets variable depending on the projection points of the jets on the first movable member.   7. Installation according to one of the preceding claims, characterized by a suction device at the projection points on the second movable member.   8. Installation according to one of the preceding claims, characterized by a means for adjusting the speed of the second movable element relative to that of the first.   9. Installation according to one of the preceding claims, characterized by a means for adjusting the distance between the two movable elements. 20   10. Installation according to one of the preceding claims, characterized by moving means of the first and second movable element in the same direction, in the opposite direction or so that the direction of movement make an angle between them between 5 and 25 90 degrees.   11. Installation according to one of the preceding claims, characterized in that the second movable element is such that fluid can pass therethrough and there is provided a third movable element and a second projection device, jets of fluid, the second movable element being, considered in the direction of the jets of the second projection device, interposed between the second second projection device and the third movable element at the point of projection of the jets on the second mobile element.   12. Installation according to one of the preceding claims, characterized in that the distance between the first and second movable element at the point of jet projection is between 5 and 200 millimeters.   13. Installation according to one of the preceding claims, characterized by a consolidation device on the second mobile element itself, or if there is a third or more, on the last mobile element itself.   14. Installation according to one of the preceding claims, characterized in that the consolidation device is downstream of the second or, if there is more, the last movable element.   A method of producing a fiber or filament web, wherein: a) an assembly of fibers and / or filaments are held together so as to be able to be defibrated by a liquid jet on a first movable element through which fluid can pass, characterized in that b) the fibers and / or filaments of the assembly are defibrated by a jet of fluid such as to project them onto a second movable element, or form a tablecloth.   16. The method of claim 15, characterized in that the speed of movement of the first mobile element is set to a different value from that of the second movable element.   17. A process according to claim 15 or 16, characterized in that steps a and b are repeated several times.   18. A method according to claim 15, 16 or 17, characterized in that the web is consolidated on the last movable element.   19. Process according to one of Claims 15 to 18, characterized in that the web is consolidated downstream of the last mobile element. 15   20. A method according to one of claims 15 to 19, characterized in that the fibers or filaments are projected on the second movable member while it is covered with a layer of textile material. 20   21. Nonwoven having long fibers or filaments and short fibers, the average ratio of length of long fibers to short fibers being greater than 10, characterized in that there are both long fibers and short fibers. short fibers in any non-woven location. 10 25