EP0489639B1 - Fiberweb for compressing - Google Patents

Description

The invention relates to a composite product based on fibers of various origins and a dry binder as well as its preparation process. The product of the invention is intended to be shaped subsequently by reactivation of the binder.

It is known to obtain parts, of high or low density, by hot molding of a primitive based on mineral fibers, in particular glass or rock fibers, and containing a binder.

These primitives can be constituted for example by mats of mineral fibers useful for insulation. When it is desired to shape a fibrous mat subsequently by reactivating the binder, it is necessary during the manufacture of the fibers by the traditional processes for producing mineral fibers intended for insulation such as glass or rock fibers to replace the binder used usually to combine the fibers in a mattress or panel intended for insulation, by a binder adapted to the process. As soon as it is produced, the fiber mat is reduced to the desired thickness, it is then immediately used, still wet as a primitive for the manufacture of molded parts.

The mineral fiber mats or felts for insulation can also be used subsequently after polymerization and storage to form a primitive for the production of molded parts. In this case, the mattress is shredded by any device suitable for individualizing the fibers in the form of flakes. At these individualized fibers are added a binder to form a composite product, which is therefore a reconstituted mat, and which is ready to be reactivated hot and shaped to obtain the part of the desired shape. Such a composite product, obtained by reconstituting a mat of mineral fiber flakes, is described for example in French patent application EP 371 847.

The previous techniques which exclusively use mineral fibers lead to end products which have given properties obtained for a given price but it is often desired to be able to keep satisfactory properties at a lower cost. It should therefore be possible to add inexpensive fibers of various origins to the usual mineral fibers.

On the other hand, the production of the previous primitive mattress leads to a ribbon of indefinite length but with a defined and immutable width. The operating conditions of this primitive mattress are such that it is often difficult to provide a plan for cutting the unit parts, each intended to be pressed separately, which makes it possible to limit falls. The only possible methods to have variable width consist in cutting the edges of the primitives before their first heating to recycle them. But this operation destroys many fibers and requires recycling the binder, which increases the cost.

For economic reasons, the process of the invention must make it possible to prepare primitive mattresses using fibers of the most diverse origins and also having the desired width, which allows the best geometric operating yields.

In the prior art, represented by patent application EP 371 847, there is used as raw material, systematically and exclusively, continuous mattresses of mineral fibers associated with each other by a binder such that they leave the fiber production lines. mineral insulation. The fibrous mattress feeds a carding unit thanks to two calendering rollers which make it advance regularly. The mattress is thus driven towards a cylindrical brush equipped with long metal bristles and of small diameter, the trajectory of the end of the bristles being tangent to one of the two drive cylinders. A comb is tangent to the carding cylinder into which it penetrates slightly to extract the fibers. After carding, the fiber flakes are deposited in an enclosure where the pulverulent binder is introduced regularly. The bottom of the enclosure is a conveyor belt which drives the fiber-binder mixture towards a calendering machine which defines the height of the mattress. This then passes through a medium temperature tunnel which allows a weak bond between the fibers thanks to the binder with thermoplastic characteristic, sufficient bond to allow the handling of the primitive mattress and its cutting into unitary primitives. The final setting of the binder is carried out - possibly much later - in the heating press finishing the part. This technique, which is well known thanks to French patent application EP 371 847, makes it possible to manufacture a wide variety of parts intended for example for the production of automobile interior coatings, rigid insulating panels or even particularly resistant thin plates. In the case where the final product is in the form of plates or panels intended to be cut or assembled in groups, the fact of working at a constant width (that of the carding machine and of the enclosure mentioned above as well as the calendering machine that follows) is not a gene. On the other hand, if one wishes to produce during the final phase of the process, hot pressing, objects with a determined shape, more or less complex such as for example the facing of an automobile door, the cutting of the product must be done before pressing and unused scraps are most often unusable. In this case, we would like to have a mattress - primitive, the width of which would be exactly suitable for cutting before pressing so as to be slightly greater than the dimension of the unit primitive or the sum of the dimensions of the unit primitives which will have to be cut there. so as to minimize falls.

Likewise, the qualities of the products that are likely to be obtained from mattresses of mineral fibers, glass fibers or rock are very varied, however, for cost reasons or because we wish to widen the field of performance, one may wish to introduce among the mineral fibers, other fibers, mineral or not, of various origins and presentations. There are two reasons for this need: either we want to see the cost price of the product drop by incorporating fibers whose cost per unit volume is lower than that of the usual mattresses because they are recovery products, various textile fibers, for example, or scrap from the various stages of the production of products based on mineral fibers. The other reason resides in the search for new properties, the incorporation of refractory fibers based on silica for example will allow, by means of the use of a suitable binder, to widen up the range of the temperatures of use. end products; another example: the incorporation of relatively rigid but looped textile fibers will make it possible to lighten and give flexibility to the finished product, or else long and resistant fibers, for example made of polyamide added to conventional mineral fibers will provide very tensile strength, etc.

The technique of patent application EP 371 847 does not allow these two objectives to be achieved: freedom of choice of the width of the primitive mattress and addition of loose fibers.

Document US 3 004 878 proposes a device for adding wet organic fibers to glass fibers for manufacturing building boards. The organic fibers are brought by air fans into the glass fiber receiving enclosure immediately after their manufacture or individually below each of the fiberizing machines. The manufacturing is done in fixed dimensions and the boards are cut after baking the resin which binds the fibers.

In patent application FR 2 268 570, there is provided an apparatus for applying a fluid material to a sheet. The fluid material leaves the applicator and falls in the form of a long current similar to a curtain and the applicator moves around a vertical axis to adapt the width of the strip of fluid deposited to that of the sheet.

The invention relates to a method for preparing a primitive mattress comprising fiber flakes and a subsequently reactivable binder, the fiber flakes being obtained by shredding a felt of mineral wool, a method in which fiber flakes are added mineral or organic unbound fibers and where a carpet of loose fiber flakes is formed in a receiving enclosure by the action of gravity alone and where the width of the primitive mattress is varied by means of the rotation of a distribution channel around a substantially vertical axis. In a variant, the thickness of the loose flake mat is adjusted at the edges by the displacement of side plates of the receiving enclosure.

Also part of the invention is a process for preparing a primitive mattress in which the unbound fibers, before entering the carding unit, are successively treated by a ball-opening machine and by a hopper with constant load. .

To carry out the process of the invention, a device has been provided for varying the width of a primitive mattress of fiber flakes to which is added a binder which can be reactivated subsequently and comprising a carding unit which is equipped with means of rotation around a substantially vertical axis. It is also expected that the reception enclosure comprises side plates with adjustment means allowing them to move laterally.

In the preferred variant of the device of the invention, the receiving enclosure is equipped with a rear vertical wall which is an extension of the upstream wall and an adjoining wall of the rectangular section channel. Furthermore, the side plates are supported on the outer edges of the rear vertical wall. It is also expected that the reception area will be equipped with a calendering mat, the plane of which remains fixed.

The main advantages of the technique of the invention can be summarized in the possibility of obtaining primitive mattresses, the composition and width of which are controlled both.

• La figure 1 représente une vue globale d'une ligne de production selon l'invention,
• La figure 2 est une représentation de la trémie de régulation de débit,
• La figure 3 montre l'unité de cardage conforme à l'invention,
• La figure 4 est une vue schématique du dispositif de l'invention,
• La figure 5 montre l'enceinte de réception des fibres à la sortie de l'unité de cardage,
• La figure 6 montre le détail de la partie aval de l'enceinte de réception,
• La figure 7 présente la partie supérieure de cette enceinte.
• La figure 8 représente le montage des plaques latérales de l'enceinte de réception,
• la figure 9 le mode de réalisation préféré de cette même enceinte.

The figures and the description which follow will make it possible to understand the operation of the invention and its advantages.

• FIG. 1 represents an overall view of a production line according to the invention,
• FIG. 2 is a representation of the flow control hopper,
• FIG. 3 shows the carding unit according to the invention,
• FIG. 4 is a schematic view of the device of the invention,
• FIG. 5 shows the enclosure for receiving the fibers at the outlet of the carding unit,
• FIG. 6 shows the detail of the downstream part of the reception enclosure,
• Figure 7 shows the upper part of this enclosure.
• FIG. 8 shows the mounting of the side plates of the reception enclosure,
• Figure 9 the preferred embodiment of the same enclosure.

In FIG. 1 is represented the entire production line for primitive mattresses 20. The main element is the carding unit 4 which is supplied in two ways, first by continuous mattresses of mineral fibers 1 and / or by unbound fibers passing through the flow control hopper 21. The solid binder (s) pulverulent (s) supplied by the worms 11 or 12 is (are) added ( s) to the flakes of carded fibers in the enclosure 10. The assembly falls on the conveyor belt 14 and is driven towards the calendering machine 15 before entering the preheating oven 16 where a binder pre-fusion associates the fibers together to constitute the primitive mattress 20 which is cut by the cutter 17 which will delimit the strips intended to constitute rolls or panels.

The other elements of FIG. 1 constitute the device allowing the preparation of loose fibers, from the most diverse origins to make a continuous sheet of unbound fibers which will be introduced into the hopper 21. One of the essential elements is the machine 23 called "ball opener" for example, the one sold by the LAROCHE Company. It comprises a feed deck 24 driven by rollers 25 towards a conveyor belt 26 equipped with spikes. The carpet 26 is inclined and drives the loose fibers upwards. The roller 27, also equipped with spikes, makes it possible to return the excess loose fibers downwards. This system makes it possible to regulate the volume flow rate of the fibers which reach the top of the carpet 26. The roll 28 has the function, thanks to the points which equip it to extract all the fibers from the carpet. The fibers are then evacuated to an outlet hopper 29 then taken up by a fan (not shown) which transports them pneumatically by the pipe 22 to the flow control hopper 21.

An important parameter of the process resides in the regularity of distribution, the homogeneity of the flakes of fibers which constitute the primitive mattress 20, in particular their regular distribution in the width of this mattress. It is therefore important that the supply of material to the carding machine 4 be regular at all times and over its entire width. The continuous mattress of mineral fibers 1 does not pose any particular problem: it is produced in the most homogeneous way possible and its distribution over the width is done in an optimal manner. A specific problem, on the other hand, is that of the constant flow rate and the width distribution of the unbound fibers arriving pneumatically through the pipe 22. The solution is provided by the flow control hopper 21. This hopper, also called "metering regulating chimney" is also marketed by the company LAROCHE, it is represented in FIG. 2, it has three essential parts, a condenser 13, a constant charge hopper 19 and a delivery system 41. All these elements are represented in a section perpendicular to their largest dimension which is always the same, equal to the width of the carding machine 4.

The stream of unbound fibers transported by the line 22 arrives in the enclosure of the condenser 13. The mechanical connection between the line 22 and the enclosure is designed so as to allow the latter to move rotating around a vertical axis without disturbing the power supply. The rotating perforated cylinder 43, the central part of which is in communication with the atmosphere, sucks the flakes on its wall while the air is evacuated after passing through the perforations. A detaching roller with blades 45 pulls the fibers which fall by gravity into the hopper with constant load 19 by passing through the hopper 52 which has the same width as all the other elements of FIG. 2: the width of the carding machine 4. The hopper constant load 19 consists essentially of two rectangular plates, a semi-fixed plate 56 and an oscillating plate 58. These plates constitute the walls of a reservoir of unbound fibers. Their horizontal dimension is the width of the carding machine 4 and their height is about five times their maximum spacing. The constant flow is ensured by the level detector 59. The spacing of the plates is adjustable according to the flow. The fibers are drawn towards the carding machine by two delivery rollers 41 whose tangential speed is that of the driving rollers 2 and 3 of the carding machine. To avoid engorgement of the reservoir constituted by the plates 56, 58, the plate 58 is driven by an oscillating movement thanks to an eccentric 60 which makes it carry out displacements of a few centimeters in the lower part. The level in the reservoir is kept constant by regulating the flow rate of the bale opening machine 23 thanks to the indications of the detector 59.

Figure 3 shows the carding unit 4 according to the invention. The two cylinders 2 and 3 rotating in opposite directions of rotation simultaneously drive the continuous mattress of mineral fibers 1 and / or the unbound fibers 18 coming from the flow control hopper 21. The function of these two cylinders 2 and 3 is only to regularly lead the materials to the carding machine 4. The materials entrained are diverse, they consist of respective proportions of mattress 1 and unbound fibers 18 eminently variable since they can have all the values of the range 0 - 1, from a raw material consisting only of unbound fibers 18 up to a raw material quine comprises that the continuous mattress of mineral fibers 1 without the contribution of any allogenic fiber. But obviously the most common proportions are intermediate between the two extreme values.

The elements of the carding machine 4 are those described in European patent application EP 371 847. In summary, we see FIG. 3, at 5 the cylindrical brush equipped with fine, long and stiff bristles 6 which carries the materials brought by the rollers 2 and 3. The comb 7 with its adjustment system 9, is made of points mounted on the plate 8 which penetrate between the bristles of the brush 5 and extract from it the flakes of fibers which fall naturally towards the elements situated below. It is essentially a hopper 54 fixed to the carding machine. This hopper ends with a rectangular section channel 55.

At the outlet of the channel 55, the fiber flakes fall freely under the effect of their own weight on the conveyor belt 14.

The principle of the variation in width of the primitive mattress 20 according to the invention is shown in Figure 4. We see on the left side of the figure that the channel 55 is perpendicular to the axis of the conveyor belt 14 and, therefore, of the mattress -primitive 20. The carding machine 4, its feeding system and the hopper 54 which is mechanically linked to it can rotate about a vertical axis 30. During this rotation, the right angle which existed between the axis of the channel 55 and the axis of the conveyor belt 14 becomes an acute angle α and the width of the loose flake carpet 57 which was L becomes L ′. These two quantities substantially verify the relationship: $$\text{L ′ = L Sin α}$$

However, it is necessary to provide additional devices which guarantee a density of the fiber flakes and / or a thickness of the fiber mat 57 which is the same over its entire width and in particular at the edges. An excellent result is obtained thanks to the association of a special receiving enclosure 10 associated with a particular calendering machine.

At the outlet of the hopper 54, the fiber flakes after passing through the channel 55 naturally fall into the receiving enclosure 10, the lower horizontal wall of which is constituted by the conveyor belt 14. The device of the invention does not include any suction below the conveyor belt 14 or any other means which would cause the flakes to crush. They are thus allowed, by avoiding any fiber breakage, any additional nesting, any preferential orientation, to keep the properties of the original products. The enclosure 10 is shown diagrammatically in FIG. 5. Among the other walls, only the rear vertical wall 53 is fixed, the wall situated towards the front is inclined and movable in its plane, it consists of a calendering belt 46 animated of a movement of translation from top to bottom in the plane of the wall. This wall is limited by two rollers: an upper fixed motor roller 47 and a free lower roller 49. This second roller can be moved along the wall which it tangents so as to produce primitive mattresses 20 of various thicknesses. The third roller 48 also free can also see its position vary so as to tension the carpet 46. This design of the calender 15 has a double advantage, firstly, the speed of the carpet 46 and that of the conveyor belt 14 can be chosen exactly identical which allows the fibers to be compressed without slipping, thus limiting their degradation. Furthermore the angle of the two belts remains identical which allows the insertion of side walls between them. Laterally, the receiving enclosure 10 is thus limited by two plates 36, 37, which can move so as to materialize the width of the primitive mattress 20.

The sixth wall of the receiving enclosure 10 is constituted by the bottom of the carding unit composed of the carding machine 4 surmounting the hopper 54 and its channel 55. This bottom serves as a cover for the receiving enclosure 10.

Figures 6, 7 and 8 show the details of the mechanical systems which constitute an embodiment of the invention. In Figure 6, first of all, there is shown the front part of the reception enclosure. We see how the movement of the roller 49 along the wall inclined, allows the thickness of the original mattress 20 to be varied from h ₁ , maximum thickness to h ₂ , minimum thickness. To maintain the tension of the calendering belt 46, the third roller 48 is moved by rotating the arms 51 which carry it around their common axis 50.

Figure 7 shows the upper part of the receiving enclosure. We can see the calendering belt 46 driven by the fixed upper motor roller 47, the fixed rear vertical wall 53 as well as one of the side plates 36. The upper wall 34 is shown insulated and the structural elements which support it are not shown. on the drawing. This wall must be capable of supporting the whole of the hopper 54, of the carding machine 4 as well as the feeding system of the carding machine. Only the hopper 54 is shown in the figure.

The plate 34 is pierced with a circular hole 35. The carding unit 4, hopper 54 and rectangular section channel 55 rests on a circular plate 31 with a diameter greater than that of the hole 35. This plate can rotate around the axis vertical 30 by means of rotating rotation shown schematically by the rollers 32. The channel 55 is provided at its end with a sheet in which it opens. This has the form of a disc 33 which substantially seals the hole 35. As the hopper 54 and its channel 55 are shown in the figure, the width of the primitive mattress produced by the installation is at its maximum. By rotating the assembly, including the circular plate 31 around the axis 30, more or less wide widths are obtained.

As we have seen, after the rotation of the carding assembly about the axis 30, it is necessary to adjust the width of the receiving enclosure 10 so that the thickness of the carpet of loose flakes of fibers 57 is constant up to the edges.

For this, it is necessary to modify the position of the two side plates 36 and 37. For this purpose, the parallelogram system shown in FIG. 8 is used. The plate 36 is generally vertical, parallel to the wall 40. It rests on the ground by pebbles not shown which are guided in grooves so that the plate 36 can move in a direction which is perpendicular to it as well as to the wall 40. Rods 38 four in number at two different levels are linked in pairs by rods such as 42. Cylinders 44 make it possible to deform the parallelogram formed by the rod 42, the wall which is parallel to it and the two rods 38. During this deformation, the ends of the rods 38 slide in housings 39 and the plate 36 approaches or moves away of the wall 40 in the direction in which the jack 44 acts. The previous system is provided by way of example, any system which allows displacement of the plates 36, 37 in general parallel to themselves is suitable. The precise position of each of the plates 36, 37 relative to the axis of the production line is to be determined empirically for each position of the carding assembly, that is to say for each value of the angle α (figure 4). In a variant of the invention, it is provided that the plates 36, 37 can be inclined around a vertical axis and / or a horizontal axis to also allow a concentration of the flakes of fibers on the edges.

FIG. 9 shows the preferred form of an element of the device of the invention, it is the receiving enclosure 10 and the end of the rectangular section channel 55. FIG. 9 is a top view of the device. The channel 55 instead of ending at the level of the plate 33 is extended on two of its adjacent sides 61 and 62. These sides extend to the vicinity of the conveyor belt 14 and form the rear wall of the receiving enclosure 10 instead of the fixed wall 53 of FIG. 5. When the upper assembly rotates around the axis 30, the wall 61 comes at 63 and the wall 62, at 64. In this variant, the walls 36, 37 are permanently supported on the free ends 65 and 66 of the walls 61 and 62. The density correction of the mattress on its edges is obtained here by tightening the downstream ends of the plates 36, 37.

The operation of the invention will appear clearly on examples.

Example 1

We want to make a very cheap product, that is to say comprising a maximum of recycled fibers.

Continuous mineral fiber mattresses produced on an industrial line may contain a certain proportion of recycled fibers, generally from scrap or defective products. In the case of the example, a glass fiber mat was available with a density of 10 kg / m ³ and a proportion of recycled fibers of 17%,

To this mattress, unbound fibers were added, which also came from scrap mineral fibers that we wanted to recycle. The respective shares of the mattress and unbound fibers, at the entry of the carding machine, were 72.3% for mattress 1 and 27.7% for fibers 8.

A reconstituted product was thus obtained comprising 40% of recycled fibers, which makes it possible to keep a relatively low production cost while keeping performance little different from that of a product which would be made entirely of new fibers.

Example 2

   soit un angle α = 50° environ.In this example, it is desired to manufacture a product intended after final pressing to constitute the internal coating of an automobile hood 90 cm wide, the other dimension being 70 cm. However, the carding machine which we have has a useful width of 120 cm, however we wish to directly produce a primitive mattress 20 with a usable width of 90 cm. The device of the invention is therefore made to rotate around the axis 30 by an angle α such that: $$\text{Sin α =}\frac{\text{90}}{\text{120}}$$

or an angle α = 50 ° approximately.

The spacing of the two side plates 36 and 37 is adapted to obtain a constant thickness in the enclosure 10.

As regards the constitution of the primitive mattress itself, it is here 70% of insulating glass fibers for 30% of large textile glass fiber yarns. length which give the product great elasticity. These threads consist of scraps from the workshop of a plastic processor, a large user of textile fiberglass mats. Here the other fibers all come from the continuous mattress of mineral fibers. As the proportion of flakes of loose fibers is relatively low, the plates 56, 58 of the regulating chimney 19 are tightened to obtain the desired flow rate (the speed of the conveyor belt 26 of the bale opener 23 is adjusted accordingly to avoid too much excess fiber at the entrance to the chimney 19). With the previous settings, a primitive mattress is obtained which has a width (90 cm) which provides the maximum operating efficiency at the final transformer which presses the primitive units to produce the covering panels for the automobile hoods.

Example 3

In order to produce a very inexpensive final composite product, a mattress of mineral fibers for insulation made up of half of recycled fibers has been used here as a raw material. This mattress accounts for 58% in the fibers of the final product. The rest, the unbound fibers which constitute 42% of the whole comes from recycled mineral fibers. This gives a primitive mattress made of 71% recycled mineral fibers. Under such conditions, such a product benefits from a particularly advantageous cost.

The preceding examples show that the technique of the invention makes it possible to manufacture, under industrial conditions, that is to say, in particular reproducible and inexpensive, products of the most diverse nature and width.

Claims (7)

1. A process for preparing an initial mat comprising fibre flakes and a subsequently reactivatable binder, the fibre flakes being obtained by shredding a mineral wool felt, characterized in that non-bound mineral or organic fibres (18) are added to the fibre flakes, in that a carpet of fibre flakes in bulk (57) is formed in a receiving containment (10) solely as a result of the action of gravity, and in that the width of the initial mat (20) is varied as a result of the rotation of a distributor duct (55) about a substantially vertical axis (30).
2. Process for preparing an initial mat according to Claim 1, characterized in that the thickness of the carpet of flakes in bulk (57) is adjusted along the edges as a result of the displacement of lateral plates (36, 37) of the receiving containment (10).
3. Process for preparing an initial mat according to Claim 1, characterized in that the non-bound fibres are treated in succession by a bale opener (23) and by a constant-load hopper (19) before undergoing a carding treatment in a carding unit (4).
4. Apparatus for varying the width of an initial mat (20) of fibre flakes, to which a subsequently reactivatable binder is added, comprising a carding unit with a carder (4), to which is fastened a hopper (54) terminating in a distributor duct (55), the assembly also comprising a receiving containment (10), characterized in that the distributor duct (55) is equipped with means of rotation (31, 32, 33) about a substantially vertical axis (30).
5. Apparatus according to Claim 4, characterized in that the receiving containment (10) comprises lateral plates (36, 37) with adjustment means (38, 39, 42, 44) allowing them to be displaced laterally.
6. Apparatus according to Claim 5, characterized in that the receiving containment (10) is equipped with a rear vertical wall which is the extension of the upstream wall (61, 63) and of a contiguous wall (62, 64) of the duct of rectangular cross-section 55, and in that the lateral plates (36, 37) bear on the outer edges (65, 66) of the walls (61, 62, 63, 64).
7. Apparatus according to Claim 6, characterized in that the receiving containment (10) is equipped with a calendering belt (46), the plane of which remains fixed.

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