FI62814C - FREQUENCY REQUIREMENT FOR FRAMSTERING AV FIBER FRAME AND UTDRAGBART MATERIAL - Google Patents

Description

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France-France (FR) 7725093 (71) Saint-Gobain Industries, 62, Bd Victor-Hugo, F-92209 Neuilly sur Seine, France-France (FR) (72) Marcel Levecque, Saint-Gratien, Jean A. Battigelli, Rantigny,

Dominique Plantard, Rantigny, France-Frankrike (FR) (7 * 0 Berggren Oy Ab (5 * 0 Method and apparatus for making fibers from a stretchable material -Forfarande och anordning för framställning av fibrer frän ett utdrag-Bart material

The present invention relates to a technique for manufacturing fibers from a stretchable material, and more particularly to the stretching of various thermoplastic materials, especially mineral materials such as glass and the like, which have been brought into a molten state by heating. It also targets the defibering of certain organic stretch materials such as polystyrene, polypropylene, polycarbonates and polyamides. However, since the device is of particular interest in the case of stretching glass and the like thermoplastics, this patent specification is directed, by way of example, to this particular application.

Some methods of using eddy currents to produce fibers by stretching molten glass are known in the art and are described, for example, in French Patent 2,223,318. A method of utilizing the formation of counter-rotating pairs of vortices in an interaction zone obtained by conducting gas is described. - i.e., as a carrier jet) into a larger main gas stream and cause it to penetrate into it, whereby a strand of molten glass <2 6281 4 is inserted into this interaction zone to be stretched therein. In the device used to carry out this method, the glass feed opening, which directs the glass fiber towards the interaction zone, is located at the limit of the main current or practically at this limit. However, it is also possible, as described in Finnish Patent No. 59576 (Pat. No. 760383), to place the glass supply opening at a distance from the main current boundary and to feed the glass fiber by gravity towards said interaction zone.

On the other hand, it has also been proposed to place both the glass feed opening and the secondary jet outlets at a distance from the main current boundary, whereby the glass strands are fed towards the jets and then enter the respective interaction zones under the action of the jets. The strands are then subjected to two stretching stages, the first in the secondary jet and the second in the main stream. This arrangement is described in detail in Finnish Patent No. 61676 (Pat. No. 773788).

In addition, according to Finnish patent No. 61676 (Pat. No. 773788), a secondary jet (i.e. a carrier jet) which brings glass into the interaction zone with the main stream causes the formation of a stable, laminar flow zone located in opposite directions of the same rotor. between the vortices formed before the main current penetrated. The glass fiber is fed to this laminar zone and then passes into a region of vortices which later merge as the carrier jet travels downstream before it reaches the main stream. In this case, the first stage of stretching occurs when the glass fiber is drawn and exposed to the vortices of the carrier jet, while the second stage, which is preferred but sometimes conditional, occurs in the interaction zone with the main stream after the carrier jet and the partially stretched strand have penetrated the main stream.

According to the present application, the vortices of the carrier jet and the flow zone of the laminator are obtained by interfering with the actual jet at each defibering center, which interference usually causes a change in the direction of the jet. This interference is achieved by placing a deflector member, i.e. a control member, in the path of the jets, and this results in a simultaneous change of direction, which contributes to stabilizing the glass supply to the system and regulating the operation 6281 4

It is a particularly important object of the present invention to stabilize a strand of glass or other stretchable material by forming a flow zone in the laminar located between the vortices formed in the gas flow. However, according to the invention, deflector members are used which are of a different type than in the above-mentioned patent application and which offer some specific, particularly interesting advantages, which are explained below.

Although the deflector members are both control members and jet transmitting members, the term "deflector" is used in this specification to mean them.

The method according to the present invention is characterized in that at least one gas jet is formed, its direction is changed as a curved path along the concave surface of the deflection member and is confined on its sides, which produces two counter-rotating vortices that the substance is fed as a strand in a stretchable state towards the concave surface of the gas jet path to the gas jet induced gases, and that a main gas stream having a greater width and path passing a deflected gas jet or deflected gas jets is greater than the energy jet path; main gas flow so that it penetrates it and thus forms an interaction zone.

Depending on the combined effect of the lateral control of the gutter-shaped deflector walls on the gutter deflector walls and the absorption of ambient gases into each jet, a central almost laminar flow zone is formed between the two vortices, and a stretch of stretchable material is then fed to this laminar flow zone. for primary stretching in this shower.

When a gas jet and associated deflector are used in conjunction with a main gas stream to perform two-stage stretching to obtain ultra-thin fibers, the main stream is directed 4 6281 4 so as to encounter a jet with greater kinetic energy per unit volume and transverse dimension of the main stream. is smaller than that so that the jet penetrates the main stream, thus forming an interaction zone. This is described in French Patent 2,223,318, which includes two counter-rotating vortices which allow a second stretching step to be performed.

According to the above-mentioned Finnish patent No. 61676 (Pat. No. 773788), a series of jets are developed which are sufficiently transversely spaced apart for adjacent jets to collide with each other at least on the downstream side of the deflector edge so that their collision favors in opposite directions. the development of rotating pairs of vortices flanking the opposite edges of the zone of near-laminar flow. Instead, according to the invention, the vortex pair flanking the zone of almost laminar flow is developed without the collision of neighboring jets, so that it is no longer necessary to observe any specific distance between the jets.

Due to the fact that the vortices are formed in the curved part of the deflector and due to this special shape, the two vortices generated in each jet have the same directions of rotation as those vortices formed in the jet-main current interaction zone. As a result, any remaining rotational motion of the vortices formed in the jets amplifies the vortices of each corresponding interaction zone.

An apparatus for converting a stretchable material into fibers by the method of the invention comprises a stretchable material supply source provided with at least one supply port and a generator with at least one outflow port for generating at least one gas jet, the device according to the invention comprising at least one deflector and comprising a curved member having a convexity directed toward the inside of the gas jet path, the stretchable material supply port being located opposite the concave surface of the curved member for feeding a strand of stretchable material to the gas jet in an area flowing in the deflection member; 5 62814 for generating a main gas flow of a larger width which intersects on the downstream side of the deflection member the path of the jet whose direction the deflection member has changed, whereby the gas jet the kinetic energy per unit volume is greater than the main gas flow.

The method and apparatus briefly described above provide an effective means of defibering a stretchable material by subjecting each strand of material to stretching, preferably comprising two steps, without interruption. Other objects and advantages of the invention will become apparent from the following description and the accompanying drawing.

Figure 1 is a schematic perspective view, partly in section and cut away, of the main members of a defibering and fiber receiving apparatus according to the invention comprising a plurality of defibering centers.

Figure 2 is an enlarged perspective view of one jet, its control member, and the flow formed, and shows the feeding of a strand of stretchable material into the jet flow.

Fig. 3 is a large-scale vertical longitudinal sectional view of the members of one fiberizing center, taken in the common plane of the jet and stretchable fiber feed source, and also shows a portion of the main stream generator 6 6281 4 and in particular some dimensions to be considered for operating the preferred embodiment of the present invention.

Figure 4 is a vertical sectional view taken along line 4-4 of Figure 3.

Figure 5 is a horizontal sectional view of the stretch material feed nipple and also shows some dimensions to consider.

As previously described, since the present invention is particularly suitable for stretching glass and similar thermoplastic materials, the following description is directed to the use of glass.

The overall view of Figure 1 shows a plant comprising six fiberization centers. Reference numeral 6 denotes a generator from which the main stream B originates and which consists, for example, of a pipe to which a burner is connected, which makes it possible to generate a hot main gas stream consisting of combustion products. The width of the main stream in the transverse direction is larger than the width of the jet row to be explained below.

The distribution box 7, which supplies gas, e.g. compressed air, to the jets is located at a distance from the main flow generator and comprises a wall with a series of outlets, each provided with a deflector member 8. As also shown in Figure 2, each deflector member 8 is preferably formed of a pipe is bent using a constant radius of curvature and one end of which is attached to a corresponding outlet of the junction box; however, the radius of curvature of the tube may be variable. The inner part of the arc, which represents, for example, about half of the pipe, has been removed. The deflector member thus comprises a trough-shaped member 9, which forms an out-of-arc part with a concavity of curvature towards the center line of the arc.

Each deflector member is associated with a glass blank or cone 10 emanating from an appropriate feed source, shown in Figures 3, 4, 5, in the form of a traction plate 11 having a width large enough to cover the entire row of jets. This draw plate is provided with a series of glass feed nipples, each of which has a dosing opening 12 which opens into a feed container 13, the edge of which forms a feed opening 13a.

As can be seen, each defibering center includes a jet transmitting member associated with a glass feed nipple, both of which further co-operate with the main stream, each defibering center operating to form a single filament.

The process at each defibering center is shown in Figure 2 which shows what happens at the start of each jet. Due to the curvature of the spray deflector member, and due to the limitation and control of the side surfaces of this jet to the trough-shaped member 9, vortices 14 develop along the opposite walls of this concave trough. The direction of rotation of these vortices is indicated by arrows. The peaks of the vortices 14 are located on the side walls of the concave trough, and as the jet goes downstream, the vortices increase and then gradually coincide with the flow L of the almost laminar between them. The near-laminar flow zone of the jet is associated with a significant input of induced air, schematically indicated by arrows? this induction of air tends to stretch the preform 10 into a glass fiber and take it with it to the jet and more specifically to the laminar flow zone between the vortices 14.

In Figure 2, the zone shown spaced downstream in reference numeral 14 indicates that the vortices gradually coalesce as the jet is directed downstream, becoming less and less distinct, as shown by the dashed lines.

The feeding of the glass fiber into the laminar flow zone between the jet vortices is denoted by the letter S in Figure 2. The filament is then entrained by the vortices and is actually subjected to primary stretching in the jet and especially in the jet between jets of the same jet pair, gradually reducing its cross-section. The fact that the glass fiber S is fed into the zone of near-laminar flow offers several advantages: in particular, it makes it possible to avoid breaking the glass fiber due to the turbulence of the zone into which the glass is fed, thus favoring the production of particularly long filaments or fibers. In addition, the air currents induced in the vicinity of the laminar flow zone automatically tend to draw the glass fiber to the central area between the vortices, and this phenomenon is strong enough to automatically compensate for the glass supply orifice extension errors with respect to the jets. As the arrows indicate, air induction continues downstream along the jet path.

Although the stretching of the glass fiber in the jet may be sufficient to produce fibers useful for certain uses, it is preferred that additional stretching is also performed using a main gas stream, thus exposing the fibers to two stretching steps.

As shown in Figure 1, the second stretching step results from each jet, guided obliquely toward the mainstream, encountering this and penetrating it, forming an interaction zone. The second stretching step takes place in this interaction zone, which is described in detail in French Patent 2,223,318 and in the aforementioned patent applications.

Comparing Figures 1 and 2, it can also be seen that the two vortices formed in each jet have the same direction of rotation as the vortex pair formed when the jet enters the main stream.

For intrusion to occur, the kinetic energy of the jet per unit volume must be greater than the main current. In addition, its cross-section, or at least the extent of its cross-section in the transverse direction of the main current, must be smaller than that of the main current. These dimensional and kinetic energy relationships must prevail, especially in the area of the zone where the shower penetrates the mainstream. As a result, since the flow at this point consists of converged vortices 14a and induced air, it is necessary to use jets whose kinetic energy at their generation, i. starting from the outlets of their junction box 7, is even larger.

Upon penetration of the main stream, each flow formed by the jet causes the formation of a vortex pair, which is schematically shown in point 15 and the vortices of which pair also rotate in opposite directions, as indicated in Fig. 1. In each defibering center, the partially stretched filament, i.e. the filament, is thus subjected to an additional stretching force due to the high-velocity currents forming the vortices 15, which makes it possible to carry out a second stretching step and to produce a thin fiber.

At the various defibering centers of such a plant, the fibers thus completed are collected, for example, on a perforated fiber receiving device such as a conveyor 16 passing over one or more suction chambers 17, making it possible to recover the fibers in the form of a mattress or mat F on the conveyor belt.

6281 4 9

The fibers can, of course, be sprayed, for example in the area where Figure 1 is cut off, with a suitable binder, such as a resin binder. The impregnated fiber mattress is then transferred to a processing station such as an oven to polymerize the binder.

As already explained, the kinetic energy of the jet per unit volume must be greater than the main flow, whatever the temperature of the gases. For example, gas supply devices connected to burners can be used, so that the main stream and the shower are both at high temperatures, so that their specific masses are low. In this case, a jet with a speed higher than the main current is used to achieve the desired ratio of kinetic energies. This ratio can also be achieved by using a gas with a relatively low temperature and thus a high specific gravity, e.g. compressed air at ambient temperature, with the main stream consisting of high temperature combustion products, in which case the jet velocity can be lower than above and even lower than the main stream. However, this adjustment leads to the desired result, i. to a jet whose kinetic energy per unit volume is greater than that of the main stream so that it penetrates into the main stream and consequently forms the desired interaction zone.

Figures 3, 4 and 5 show the mutual positions of the three main members of the defibering center, namely the main current generator, the jet transmitter and the source of the stretching material supply. They are marked with symbols denoting various parameters and, more specifically, certain distances and certain angles, to which the following tables refer, giving both the appropriate ranges and the preferred values of the dimensions and angles.

Table I

Traction plate and stretch material feed nipples

Symbol Default value (mm) Range dT 2 1-5 1T 1 1-5 1R 5 0 - 10 dR 2 1-5 D 5 1-10

R

10 6281 4

Table II Shower transmission

Symbol Primary value (mm, degrees) Range d 2 0.5-4 1 3 1-15

Yj 5 1.0 - ctD 45 ° 20 - 90

Rd 2.5 2-3

dJ

Table III Main current

Symbol Default value (mm) Range 1-10 5 - 20

D

Table IV

Mutual positions of different bodies

Symbol Primary value (mm, degrees) Range aJB 45 20 - 90 XBJ - 5 + 10 - - 20 XJF 5 1-8

Zjp 5 0 - 15 Z „20 15 - 35

Zdb 16 0-30 1D 2 1-3

dJ

As for the symbol 'XBJ, its negative values correspond to the case shown in the figure in which the main current transmission tube is located upstream of the secondary jet transmission port with respect to the main current propagation direction.

On the other hand, as far as Z_n is concerned, it is stated that its value is zero, which

Un kä corresponds to the position of the lower edge of the deflector at the main current boundary; wherein the jet vortices continue and intensify in the interaction zone formed with the main current, so that a better continuity of the stretching effects of the jet and the main current is achieved.

The number of defibering centers can be as high as 150, but in a normal defibering plant for glass or similar thermoplastic material, a suitable draw plate comprises, for example, 70 feed nipples.

The term "feed opening" for the material to be stretched used in this presentation is to be interpreted very broadly; it may in fact mean either a separate list, an opening for feeding material to the jet flowing in the deflector member, or a feed gap associated with the jet row, or a series of feed openings. The feed orifice row can in fact be replaced by a gap located transverse to the main stream downstream of the jet row and associated deflector members, whereby the material leaving the gap is divided into a series of cones and strands by jets and induced air currents. according to the flow zone of the female.

It should also be noted that the operating conditions of the system according to the present invention vary as a function of several factors, for example the properties of the material to be defibered. As mentioned above, the invention can be applied to a wide variety of stretchable materials. The temperature of the drawing plate, i.e. the feed source, will of course vary depending on the material to be defibered in each case, and in the case of glass or other inorganic thermoplastics it will generally vary between about 1400 ° and about 1800 ° C. In the case of a glass type of the conventional type, the temperature of the drawing plate is about 1480 ° C.

The unit flow can vary between 20 and 150 kg per hole in 24 hours, with typical values being between 50 and 80 kg per hole in 24 hours.

Certain values for jet and mainstream, which are shown in the following tables, are also important. The following symbols are used: P = pressure T = temperature V = velocity p = volumetric mass 12 6281 4

Table V Shower output

Symbol Primary value Range

Pj (baria) 2.5 1-50 TT (° C) 20 10 - 1100 d

Vj (m / sec) 300 200 - 900 p TV_2 (bar) 2.1 0.8-40

d J

Table VI Main current

Symbol Primary value Range PB (mbar) 95 30 - 250 T_ (° C) 1450 1350 - 1800

D

νβ (m / sec) 320 200 - 550

PgVg2 (barium) 0.2 0.06-0.5

When both the jet and the main stream are used at the same time, the width of the jet and preferably also the cross-sectional area are smaller than the main stream as described above, and the jet must penetrate the main stream to form an interaction zone where the second stage of stretching takes place. For this purpose, the kinetic energy of the jet per unit volume must be greater than the main current in the area in which they interact. A particularly suitable ratio of these kinetic energies per unit volume is approximately 10: 1, i.e.:

PjV - 10

oBV

In addition to certain advantages already present in previous applications, the process of the present invention offers some very specific advantages which are of interest in the defibering of a wide variety of materials, and in particular thermoplastic mineral mixtures such as glass and the like. Thus, according to it, good stability can be achieved in the glass feed and thus in the glass cone, regardless of * ·. j.

13 6281 4 a considerable distance between the main members of the system and, more specifically, the distance between the glass supply source, the jet transmitter and the main current generator. Namely, the location of these members far apart makes it possible to stop the desired temperature in each of them, with the desired accuracy, in order to achieve efficient and regular defibering.

According to the invention, it is also possible to form highly stable vortex pairs for the jet flow, which stability is due in particular to the fact that the peaks of the vortices are located inside the deflector, in a trough-shaped curved part, and are thus fixed in a stable position.

This results in high stability in the supply of stretchable material. The use of a gutter-shaped deflector for each jet separately makes it possible to create vortices in each flow independently of the adjacent jets, which offers the advantage that the distance between the jets can be chosen arbitrarily.

Claims (8)

A method of converting a drawable material into fibers by means of gas streams, characterized in that at least one gas stream is generated, that its direction is deflected to extend in the form of a curved path along the concave surface of a deflector member and is limited from the sides, which give rise to two rotating swirls in opposite directions, the peaks of which are located on the lateral surfaces of the deflected gas jet flow, and that the material is measured in the form of a string in a pullable state against the concave surface of the path of movement of the gas jet in gases induced by the gas jet; and, optionally, generating a larger width main gas stream whose path of movement intersects the path of the deflected gas beam or the deflected gas beams, the gas beam having greater kinetic energy per unit volume than the main gas stream, zone of interaction. Method according to Claim 1, characterized in that the material strand is fed into a laminar flow zone located between the two rotating swirls in their upstream part in opposite directions. Method according to Claim 1 or 2, characterized in that the deflection and restriction of each gas jet takes place at a distance from the boundary of the main gas stream, wherein the material stream fed into each zone with laminar flow is subjected to an initial pull in the deflected gas jet. drawing in the zone for interaction with the main gas stream. 4. A method according to claim 1, characterized in that the deflection and the lateral restriction of each gas jet occurs in the vicinity of the main gas stream boundary, so that the two vortices generated in the gas jet continue and are enhanced in the zone for interaction with the main gas stream. Process according to any of claims 1-4, characterized in that the gas jet has a temperature close to the ambient temperature. Apparatus for converting a pullable material into fibers by the method of any one of claims 1-5, said device comprising a feed source of drawable material provided with at least one feed orifice and one having at least one outlet orifice for generating of at least one gas jet, characterized in that the device comprises at least one deflector member (8) into which the gas jet is inserted and comprising a curved member (9) whose concavity faces the interior of the gas jet's path of movement, the feed opening (13a) for the pullable material is located opposite the concave surface of the curved member for feeding a string of pullable material to the gas jet within the area where it flows in the deflector means, and the device optionally further includes a generator (6) for generating the a main gas stream (B),