HUP0103092A2 - Man-made vitreous fibre batts and their production - Google Patents

Abstract

The subject of the invention is an apparatus for the production of MMVF cotton, which consists of the following components: (1) first and second centrifugal spinning devices, optionally one or more third spinning devices, where each spinning device contains a fiber-forming rotor, (2) means for feeding the MMVF melt into the spinning devices, ( 3) devices for feeding the fibers from the spinning devices into an air current, (4) a permeable conveyor belt that collects the fibers into a quilt, (5) devices for cross-folding the quilt, and (6) devices that can be used to select fiber formation parameters on the spinning devices. The invention also includes a special, integral MMVF wadding. Figure 1 Oh

Description

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EXAMPLE Artificial glass fiber wadding and its production

The invention relates to the production of man-made glass fiber (MMVF) batts and in particular to apparatus and methods by which the construction of the batt surfaces can be optimized independently of the optimization of the batt core construction. The batts are also a subject matter.

The usual method of making a MMVF batt consists of centrifugally spinning a mineral melt into a cloud of MMV fibers in air using a centrifugal spinner placed in an air stream, collecting the fibers on a permeable conveyor belt into a mat with opposing edges by extracting air from the cloud through the conveyor belt while the conveyor belt is moving in a first direction and overlapping the mat crosswise to make the batt.

Various types of spinnerets are known for converting mineral melts into fibers. Many of these consist of a disk or cup which rotates about a substantially vertical axis. These spinnerets are usually arranged in a row, i.e. in a substantially first direction, as is described, for example, in GB 926,749, USP 3,824,086 and WO 83/03092. Usually, the same melt is fed to each spinneret, so that a substantially homogeneous product is produced. However, it is known from FRP 1,321,446 to deposit organic fibers on the surfaces of the product and also to feed a binder or other material into the cloud of fibers. USP 3,824,086 mentions that if the spinning devices are arranged in two rows, side by side, the disadvantage is that the product is not identical along the center line of overlap.

Different spinning apparatuses are those which comprise at least one fiber-forming rotor mounted on a substantially horizontal axis. Such spinning apparatuses may have one or a pair of rotors to which the melt is applied and from which the fibers are formed, but more typically the spinning apparatuses are cascade spinning apparatuses in which the melt is fed to a first rotor and from which it is sprayed onto a second, third, and optionally fourth successive rotor, where fiber formation takes place on the second and further rotors, often also on the first.

The properties of the fibers formed on each spinning apparatus depend on the fiber formation parameters of the given spinning apparatus, namely those parameters of the apparatus that influence fiber formation.

One important fiber-forming parameter is the material quality of the melt fed to the spinneret, in that fiber formation is influenced by changes in the physical properties of the melt (especially changes in its viscosity, which depends on both temperature and chemical composition) and fiber characteristics change with changes in the chemical composition of the melt.

Another fiberization parameter is the melt feed rate to the spinneret. Generally, longer fibers and stronger batts are obtained with lower than higher feed rates (all other parameters being constant).

Another fiber formation parameter is the position of the rotor or at least one of them that forms the fiber relative to the melt feed point into the spinner. For example, the melt is usually dripped onto the rotor or the first rotor of the spinner and the angle of the melt flow with the rotor surface affects the efficiency of the spinner. Similarly, if there are rotors arranged in series, the position of each rotor relative to the others can affect the efficiency.

Another spinning parameter is the acceleration field created by the rotor or rotors (fields if there are multiple rotors). The acceleration field depends on the diameter and rotation speed of the rotor.

There is usually an air stream associated with the or each spinning rotor, where the fibers formed on the rotor surface are contained in this air stream. This air stream has a flow field and each flow field is associated with a spinning device, which is another important spinning parameter.

In conventional processes, a single cascade or other spinning apparatus is arranged to form the fiber from the mineral melt and the fibers are dispersed in the air as a cloud of fibers. The fibers are collected as a blanket on a permeable conveyor belt having opposing first and second edge areas and a central area, such that air is drawn from the cloud through the conveyor belt.

Quilts often have varying structures or properties, and for this and other reasons, it is common practice to cross-fold the quilt to produce a batt, the first face of the batt being formed mainly by the first edge portion of the quilt and the opposite face of the batt being formed mainly by the second edge portion of the quilt, the batt further having a core portion between the first and second faces.

It is usually desirable for the wadding to have a uniform composition throughout its thickness, as much as possible, i.e. it is preferable that there is no intentional difference between the first face, core and second face of the wadding.

For certain purposes, batts are required that have varying properties throughout their thickness, but this is traditionally done by making a substantially homogeneous batt and then treating it to modify its surface properties. For example, it is known to apply an extra binder to one surface and/or to cut a face from the batt mass, treat it, and then re-combine it with the batt mass, and it is also known to laminate a thin batt into a thicker batt having different properties.

It is known to vary the spinning conditions on a single spinning apparatus by changing the spinning parameters. Examples of such methods are described in USP 3,159,475 and 4,210,432, EP-A 080,963, WO 92/10436, WO 92/12940 and WO 96/18585. In some of these methods, the change is made during the process, in other cases before the process is started, by selecting the spinning parameters accordingly.

Although conventional methods use a single cascade or other type of spinner, there have been proposals in the literature to provide first and second spinners arranged side by side, and optionally a third spinner between the first and second spinners. The fibers from all three spinners form a single, air-entrained fiber cloud, and when this fiber cloud is collected on a conveyor belt as a mat, the first and second spinners provide the fibers that form the first and second edge portions of the mat, and if there is a third spinner (or more), the third spinner (or more) provides the fibers that predominantly form the center portion of the mat.

For example, a method has been described which uses a pair of rotors, one of which is arranged as a mirror image of the other. The fact that one is a mirror image of the other does not result in the two spinning devices having different fiber formation parameters.

The use of three cascade spinners arranged side by side is described in WO 92/12940. This teaches that the relative position of the axes of the different rotors should be controlled in order to optimize the fiber formation. There is no suggestion in WO 92/12940 that the relative position of the rotors within a cascade spinner should be different from the relative position of the rotors of the three cascade spinners as illustrated.

Since in previous professional practice the aim was generally to provide a web which was as homogeneous as possible, it is logical that the spinning parameters of the spinning apparatus should be set in the same way on each spinning apparatus, although EP-A 374,112 describes varying the concentration of the binder or colouring additive across the width.

The present invention is concerned with two different problems.

One problem arises from the fact, as mentioned above, that it is often desirable to produce batts in which one of the edge portions has different properties than the core portion. For example, in some cases it may be desirable for the fibers in the edge portion to have a different average fiber diameter or average fiber length than the fibers in the core portion. This would allow the top view properties of the batt to be optimized independently of each other and the insulation or other physical properties of the batt. Currently, this problem is solved by splitting the batt thickness and treating one of the different slices before rejoining them, or by treating the surface of the quilt or by layering separately formed batts.

One object of the invention is to provide novel waddings that have different properties in a controllable manner along their thickness, as well as an apparatus and method for producing such waddings.

A second problem arises when two or more spinners are used side by side to make a single blanket. The nature of the process and the structure of the collection chamber make it difficult to observe exactly what is happening on each spinner. However, we have now recognized that in a set of two or more spinners, the operation of the individual spinners can be relatively independent of each other even if the spinners are intended to operate similarly. Thus, if two spinners of substantially the same rotor diameter and speed and the same melt flow are placed side by side, it is predictable that the yarn production and yarn quality of each spinner will be the same. In fact, we have now realized that this is not necessarily the case and two spinners that are intended to be identical and are intended to be operated under the same conditions will often in fact have different yarn production or different yarn properties or both.

The reason for this is unclear, but it is likely related to the difficulty of setting any set of process operating conditions with complete reliability, given the high temperatures, high rotor speeds, and high air velocities that occur in each spinner. Also, since the spinners are necessarily located at different locations relative to the collection device, this locational difference may contribute to the efficiency difference, for example because the air flows around each spinner differently. Whatever the case, it is believed that systematic or sometimes spontaneous variations occur and reduce the efficiency of the entire manufacturing process.

Accordingly, the invention also aims to realize the existence of this problem and to solve it in such a way as to avoid unwanted and uncontrolled variations in individual spinners placed side by side in a spinner series. In this way, we could increase the efficiency and avoid variations along the edge of the quilt and therefore in the thickness of the batting.

According to the invention, we provide novel batts that have different properties along their thickness and provide an apparatus and method that is capable of solving both problems, namely, the production of these novel batts and the avoidance of undesirable variations in the quilt.

The apparatus for producing MMVF wadding according to the invention consists of the following:

first and second centrifugal spinnerets arranged substantially side by side and optionally one or more third devices between the first and second spinnerets, each centrifugal spinneret comprising at least one spinneret rotating about a substantially horizontal axis, the or each rotor providing an acceleration space, means for feeding the MMVF melt to each of the spinnerets, means for entraining the fibers from each of the spinnerets in an air stream around the spinneret of each spinneret, the air stream having a flow space, thereby forming a single air-entrained fiber cloud, a permeable conveyor belt for collecting the fibers into a web having first and second opposing edge portions and a central portion, and means for drawing air from the cloud through the conveyor belt, whereby the first and second spinnerets form the fibers, which provide the first and second edge portions, respectively, and means for cross-lapping the batt to form the batt, wherein the first front side portion of the batt is formed mainly from the first edge portion of the batt, the opposite second front side portion is formed mainly from the second edge portion of the batt, the front side portion is formed mainly from the second edge portion of the batt, a core portion is provided between the first opposite and second front side portions of the batt, and in this apparatus there are means for independently selecting two or more fiberization parameters on one or different spinning apparatus(es), wherein these parameters are: (a) the physical properties or chemical composition of the melt fed to the spinning apparatus, (b) the rate of feeding the melt to the spinning apparatus, (c) the positioning of the fiberizing rotor or at least one of the fiberizing rotors on a spinning apparatus for feeding thereto! relative to the location at which the melt is fed to that spinner, (d) the acceleration range or ranges of that spinner, and (e) the flow area of the or each air stream associated with a spinner.

The method for preparing MMVF cotton wool according to the invention consists of:

a mineral melt is centrifugally formed into fibers by feeding the melt into first and second centrifugal spinners arranged substantially side by side and optionally into one or more third centrifugal spinners between the first and second centrifugal spinners, each centrifugal spinner comprising at least one fiber-forming rotor rotating about a substantially horizontal axis and each of the rotors or rotors creating an acceleration field, the fibers from each spinner are blown around at least one rotor of the spinner by an air flow, the air flow having a flow field and thereby forming a single fiber cloud in the air, the fibers are collected on a permeable conveyor belt into a blanket having first and second opposing edge portions and a central portion by extracting air from the cloud via the conveyor belt, whereby the first and second spinners form the fibers which are the first and second an edge portion is provided, and the batt is overlapped to form the batt, whereby a first end portion of the batt is formed mainly from a first edge portion of the batt and an opposite, second end portion of the batt is formed mainly from a second edge portion of the batt, and the batt has a core portion between the first and second edge portions, and in this process, the centrifugal fiberization can be controlled by selecting two or more fiberization parameters of one or different spinnerets: (a) according to the physical properties of the melt fed to the spinneret and/or the chemical composition of the melt, (b) according to the flow rate of the melt to the spinneret, (c) according to the feeding position of the fiberizing rotor or at least one of the fiberizing rotors to that spinneret, (d) according to the acceleration field or fields of a spinneret, or (e) according to the flow field of the air flow or each air flow associated with a spinneret and at least two of the fiber formation parameters are adjusted [on one or different spinnerets] before or during the production of the MMVF batt by varying one or more of the batt edge-part or core-part properties such as (1) average fiber diameter, (2) average fiber length, (3) fiber content, (4) fiber tensile strength, (5) density, or (6) chemical composition.

In this way, at least two spinning parameters of one or different spinning apparatus(es) are different during the process.

The invention relates to apparatus and methods in which at least two parameters can be adjusted on one of the spinning devices and one or all of the other spinning devices are not adjusted during the process. In fact, these other spinning devices may be of such a design that it is difficult to achieve adjustment of the parameters on them (i.e. the spinning devices and their melt flow cannot be easily designed to allow such adjustment.

In other methods and apparatuses of the invention, adjustment of at least two parameters is achieved by adjusting one parameter on one spinning apparatus and the other parameter on a second spinning apparatus. Adjustment of any one parameter on any other spinning apparatus may be difficult to achieve. Further adjustment of the second or subsequent parameters may be difficult to achieve on adjustable spinning apparatuses, but is generally possible.

It is however usually possible to adjust at least one parameter, and usually at least two parameters, and often all parameters, on at least two (and usually all) spinning devices. Often at least two parameters are adjusted on one spinning device during the process, while one or more parameters of the other spinning device or devices are not adjusted.

According to the invention, in practice at least two parameters must be adjusted (or different parameters on two different spinners or at least two parameters on one or more spinners) because it has been recognized that in a spinning process comprising several spinners, adjusting a single parameter does not provide sufficient control to achieve the fine control of the process required by the invention. In the event that, for example, one of the spinners is not performing well, simply adjusting the amount of melt fed to the spinner will not achieve the desired efficiency. Instead, in practice it will be necessary to change at least one or more other parameters, for example one or more acceleration values of the air flow fields, to compensate for the changes resulting from adjusting the melt amount parameter.

The adjustment of the at least two parameters may be primarily intended to provide a uniform or more uniform quilt. For example, the adjustment may be primarily intended to vary the yield across the width of the quilt, for example, to provide edge portions that have a higher fiber density than would otherwise be the case, for example, to provide a substantially uniform fiber density and fill content of the quilt across the width of the quilt.

Thus, this subject of the invention makes it possible for the first time to optimize the operation of known double and triple spinning processes.

The invention has particular value when carried out with the deliberate intention of making changes across the width of the quilt, such changes generally relating to average fiber diameter, average fiber length, fill content or chemical composition.

The subject of the invention in this regard enables the manufacture of a new product. This new product consists of an integral MMVF wadding having a first face portion extending inwardly from one face portion, a second face portion extending inwardly from the opposite surface, and a core portion between the first and second face portions, the portions being integral with each other, the core portion having at least one characteristic that differs from one or both faces.

-part, where these properties are average fiber diameter, average fiber length, fiber content, tensile strength, density or chemical composition. Preferred novel products are advantageously characterized by an observable difference in fiber diameter, fiber length, fiber content and fiber composition (or sometimes a difference in tensile strength).

By the term integral, we mean that the parts are one with each other, which is the result of the air-spreading of the batt and the folding of the batt upon itself. This fiber distribution differs from the fiber distribution according to the prior art methods, where a front portion is formed and laminated with the rest of the batt. Even if the lamination is carried out under conditions that maximize the interconnection of the fibers, the individual parts are not integral with each other in the sense that is achieved when they are formed by overlapping according to the present method.

The spinning apparatus used in accordance with the invention may be any centrifugal spinning apparatus having one or more fiber-forming rotors rotating about a substantially horizontal axis.

Generally, however, each spinning apparatus is a cascade spinner, so preferably each spinning apparatus used for making quilts is a cascade spinner comprising a rotor rotating about a substantially horizontal axis and at least one further rotor rotating about a substantially horizontal axis and arranged to receive the melt discharged from the first rotor and discharge it in the form of fibers.

Typically, there is a first rotor on which some filaments may be formed, but which serves mainly to accelerate the melt and disperse it onto a second rotor, a second rotor which forms filaments and disperses the melt onto a third rotor, and the third rotor either converts the entire melt into filaments or disperses the melt onto a fourth rotor which converts the entire melt into filaments. The filamentation on at least the second or subsequent, and optionally the first rotor, is carried out in an air flow which can influence the filamentation.

Suitable cascade spinning apparatus are described in GB-A 1,559,117, WO 92/06047, WO 92/12939 and WO 92/12940.

One way of varying the yarn properties on different spinnerets is to vary the amount of melt, and this is particularly important where the spinnerets are cascade spinnerets. It is therefore desirable to be able to control very precisely the amount of melt discharged from each individual spinneret. It is generally advantageous to provide a single melt from a single furnace for each spinneret and in such cases it is appropriate to provide suitable drippers which feed a single melt from the furnace to each spinneret. It is difficult to precisely control the melt flow if it flows through a single dripper to the spinneret and this is particularly difficult if a single rigid dripper system is used to supply melt to three or more spinnerets. For example, it is not suitable to provide the dripper with adjustable weirs.

We have developed a device for forming synthetic glass fibers with multiple cascade spinners, which allows the melt flow to each spinner to be optimized individually. This device allows the amount of melt delivered to one spinner to be controlled independently of the amount of melt delivered to the other or multiple spinners.

In this regard, the invention provides an apparatus for producing MMV fibers comprising first, second and third centrifugal (usually cascade) spinnerets arranged side by side and a rigid sluice means for receiving melt exiting the furnace at a feed location and feeding it from first, third and second discharge locations to the first, third and second spinnerets, wherein the sluice means has first and second sluice arms extending generally in opposite directions across the receiving location, away from the first and second discharge locations, and a third arm extending generally forward from the receiving location toward the third discharge location, and the apparatus includes means for independently tilting the sluice about a generally horizontal axis - generally extending transversely and about a generally longitudinally extending axis - wherein the The flow rate at the first, second and third discharge points can be controlled independently of the other points.

The drip device is essentially T-shaped, with the base of the T acting as a third drip arm and extending forwardly, and the drip element pivoting about a substantially horizontal (forward-looking) axis which is substantially parallel to the base of the T and pivoting about a horizontal axis which is substantially perpendicular to the forward-looking axis. "Forward-looking direction" is understood to mean a substantially horizontal direction which is substantially perpendicular to the transverse direction which extends between the first and second discharge locations.

Although this dripper is a preferred device for feeding a single melt to three spinnerets, it is also possible to use other means to control the rate of melt feed to one or more spinnerets, independently of the rate of melt feed to other spinnerets. A suitable device is described in PCT/EP98/00274.

In order to be able to use a single apparatus to produce a range of products that range from two or more products that are uniformly thick across the width of the quilt, in a deliberate manner, to products that are uniformly thick across the width of the quilt (and the thickness of the batting), it is necessary that each of the spinners be independently controllable such that at least two defined fiber forming parameters are independently controllable. One or each of the centrifugal spinners is preferably independently controllable by independently selecting at least two of the defined fiber forming parameters. Preferably, at least one spinner, and more preferably each spinner, is independently controllable by independently selecting three, four or five defined parameters.

The independent selection can be made before the process is started. For example, one of the spinners can be designed to produce different fibers from the others. For example, if the spinners are cascade spinners, one or more of them can be a three-rotor spinner, while one or more of them can be a four-rotor spinner. In general, however, each of the spinners has the same number of rotors, usually three or more preferably four.

One or more of the spinners may be constructed to have a rotor or rotors of different sizes from the other or more rotors. For example, one or more of the rotors may be constructed in accordance with WO 92/06047, while the other or more rotors may be constructed in accordance with WO 92/12939 or WO 92/12940.

However, independent control of one or more spinnerets consists in selecting two or more fiber forming parameters independently of each other at the start of the operation or during the operation. Thus, at the start of the operation, a combination of fiber forming parameters can be selected that takes into account the desired end product or can be changed during the operation. If two or more parameters are varied during the operation, this control and independent selection according to the invention can be carried out in response to spontaneous or undesired variations in fiber production. For example, if it is observed that the fiber production of one of the spinnerets spontaneously decreases, then one or more of the fiber forming parameters are adjusted to restore the yield to the desired value.

More commonly, however, the change is made during the manufacturing process in such a way as to change the quality of the product, so for example the invention provides the possibility of changing production from one type of product to another.

At least two of the fiber forming parameters may be adjusted automatically or manually. For example, the desired edge-part or core-part properties may be programmed into a control system that operates the entire apparatus, wherein the fiber forming parameters are automatically adjusted to achieve the desired properties. A suitable control system is described in EP 97309674.6.

One of the tuning fiberization parameters relates to the melt itself. Parameters may include its physical properties (usually its viscosity) and/or its chemical composition. Viscosity is affected by both temperature and the chemical composition of the melt, and viscosity affects the fiberization process.

Thus, if the spinnerets are otherwise similar, but the melt has a different viscosity as it reaches one spinneret or another, the yarn quality will be different. If there is a significant difference in viscosity as the melt reaches the spinnerets, this difference is usually at least 10 cps, often at least 20 or 30 cps. It may be 200 cps or more.

If there is a difference in melt temperature as the melt reaches the spinnerets, this is generally at least 10°C, for example at least 20°C and may be 50°C or even 100°C. If there is a difference in chemical composition, this may be a relatively small difference, for example at least 1 or 2% by weight of at least one melt component (measured as oxide), but may be much larger, for example at least 5 or 10% or more of one or more melt components.

Another difference in spinning parameters that can be used is the melt flow rate, especially when the spinnerets are of substantially the same design. For example, if each spinneret is of substantially the same design, increasing (or decreasing) the feed (in kilograms per hour) to one spinneret by at least 5 or 10%, often by 30-60% or more, can make a significant difference in the fiber quality on that spinneret.

Another variation in the spinning parameters that can be used is the position of the spinning rotor or at least one of the spinning rotors relative to the location where the melt is fed into the spinneret. For example, the entire spinneret can be moved laterally to change the angle at which the melt reaches the spinneret by at least 5° or 10° from a value approaching 90° to a value significantly less. Alternatively, the entire spinneret can be rotated about a horizontal axis, as described in USP 3,159,475, typically by at least 5° or the individual rotors can be moved vertically and/or horizontally relative to each other. One or more spinning devices can be oscillated about a vertical axis or can be adjusted to a specific angle relative to the longitudinal direction of movement of the fiber cloud to direct the cloud in a selected direction. A suitable method and apparatus for adjusting each of the spinning device or devices is described in EP-A 825,965.

The invention also includes methods in which the change in the fiberization parameters consists in stopping the supply of melt to one or more spinners, provided that at least two spinners continue to receive melt for fiberization. Thus, in the case of three spinners, the invention also includes methods in which the supply of melt to one or two spinners is stopped, and so on. This may have the advantage that the stopped spinner can still be used as a medium for spraying primary and optionally secondary air and/or cooling water and/or binder from the spinners, but without adding fibers to the material that is collected as a blanket.

The other filamentation parameter that can be varied is the acceleration field or fields. This is defined as the acceleration field on the surface of the rotating rotor and as the centripetal acceleration of an element of the wheel surface with radius r (m) and angular velocity ω (sec - ¹ ):

a = r ω ² (m.sec' ² ), where ω = 2 πη/60, and na is the number of revolutions per minute.

This change can be achieved by replacing one of the rotors with a rotor of a different diameter (as discussed above), but this is achieved in the usual manner according to the invention by changing the speed of rotation. If each spinning apparatus has more than one rotor, the change can be made on all rotors or on only one rotor or some of them.

If the acceleration field is varied, the increase is usually at least 10%, often at least 20% and may be 50% or more. For example, if the spinners each consist of a single rotor, then the acceleration field on one of them may be at least 10% greater than on the other, while in the case of a cascade of spinners, the acceleration field on the first or second rotor or on one or more additional rotors will generally be at least 10% greater on one spinner than on the corresponding rotors of the other spinners.

In cascade spinnerets, it is advantageous to provide the air flow of each fiberizing spinneret with a primary air flow which substantially contacts part or all of the circumference of each of the further rotors and optionally also part or all of the circumference of the first rotor. For example, there may be an air gap (slot) which has a diameter substantially equal to the diameter of the rotor and which is arranged to guide the primary air flow over the circumference of the rotor. This first air flow is generally supplemented by a second air flow which flows around the primary air flow.

The primary air stream may exit from directing devices located adjacent to the circumference of the or each rotor and directed coaxially or conventionally at an angle α = 5°-60° to the velocity vector and axial direction such that the tangential component rotates with the rotor.

The guide means on one or more rotors of a spinning apparatus are often arranged to exert a larger tangential component on the primary air flow of one or more rotors of one or more spinning apparatuses, typically at least 5°. If there is a third spinning apparatus, this is usually the one with the largest angle. The largest tangential angle on the third spinning apparatus is at least 5° larger than the largest tangential angle on the first and second spinning apparatuses and is typically at least 20°. However, in some embodiments, it is advantageous to have a larger angle on the first and second spinning apparatuses, as this facilitates the production of fibers with higher tensile strength.

In order to minimize the amount of fiber cloud that hits the walls of the collection chamber, it may be advantageous to arrange the primary air flow guide means so that they are positioned at different angles on different parts of each rotor, so that - taking into account the construction of the collection chamber - the tangential angle can be optimized to maximize the tensile strength while minimizing the impact of the fiber cloud on the walls of the collection chamber.

The variation of the spinning conditions can therefore take place in the flow space of the air stream. The air stream can consist of only a primary air stream or of a primary and a secondary air stream, where the secondary air stream surrounds the primary air stream. In this way, the velocity vector of the primary air stream at a certain point in one of the spinning devices can be greater, usually by at least 10%, often by 30-80%, than the velocity vector of the primary air stream at a substantially corresponding point in another spinning device, and/or the velocity vector of the secondary air stream can be greater at a certain point by at least 10%, often by 30-80%, than the velocity vector of the secondary air stream at a substantially corresponding point in another spinning device.

There is often an adjustable primary air flow together with a secondary air flow, which can be provided, among other things, by an auxiliary air flow located below the spinner, which creates a relatively strong air flow forward and upward to direct the flow field into the collection chamber and minimize fiber loss in the stack, which is usually located in front of and below the spinner for collecting fiber waste.

The velocity vector of the primary (and/or secondary) air stream can be simply varied by the spinner and the air flow rate therefrom, for example, when the air or a portion thereof flows co-axially with the spinner and parallel to its axis, although it may be desirable to introduce a tangential component into this air stream as it approaches the spinner. The tangential component, as described above, is applied to the primary air stream near the periphery of each of the spinners or spinners to modify the fiber formation conditions on the surface of the periphery of the spinner rotor or rotors.

By changing this angle, the velocity vector can be varied. For example, the angle of a velocity vector of a specific value at a given point on a spinning device may differ by at least 5° from the value of the same velocity vector at the corresponding point on another spinning device, which is the result of there being at least a 5° difference between the airflow orientation of one spinning device and the airflow orientation of another spinning device at that location.

Each spinning device can be mounted independently of the other spinning devices and its construction and assembly can be as described in WO 96/38391. For example, each spinning device can be constructed with its own substantially tubular conduit as shown in Figure 6 of WO 96/38391. These two conduits can open into a collection chamber, the construction of which is described in WO 96/38391. Reference should be made to this for a full description of the substantially tubular conduit, the spinning device and the entire apparatus.

Instead of mounting each spinner in its own substantially tubular conduit, the preferred methods of the invention mount two or more spinners in a single conduit, which will be generally oval in shape to allow two or more spinners to be housed in the conduit. In addition to being oval rather than substantially circular, the conduit and other details of the apparatus are as described in WO 96/38391. For example, guide members may be provided on the inner surface of the conduit wall which may be shaped or adjusted to provide different non-axial motions to different axial segments of air flowing past the spinner and thus become the secondary air discussed above.

The conveyor belt must be wide enough to accommodate the fibers coming from two or more spinnerets. The edges of the conveyor belt are often defined by the walls of the collection chamber, but air currents or any other suitable method can be used to confine the fiber cloud within the boundaries. The velocity vector of the primary gas streams then preferably has an axial and co-rotational tangential component.

The batt formed on the conveyor is overlapped crosswise to form a batt. This may be done by a swinging pendulum technique or any other method whereby lengths of batt can be laid crosswise to the direction of travel of the batt such that each first edge of the batt forms one surface of the batt and the second edge of the batt forms the opposite edges of the batt. An example of an overlapping system that does not include a pendulum overlapping system is described in PCT/EP97/00965.

The batt may be continuous in length, in which case it will assume a zigzag shape in the batt. When the overlapping is carried out in this manner, the angle of each wing with the transverse direction is usually less than 15°, preferably less than 10°. Usually at least 4, preferably 8 or more, for example up to 20, batt wings are overlapped to form the full thickness of the batt. As a result of overlapping at least 6 wings, which extend from one surface of the batt to the other, it is ensured that the first face is mainly (for example at least 80% by weight) formed by the fibers of the first opposite edge of the batt and the second face is formed by the fibers of the second opposite edge of the batt, and the batt is integral in the sense that it is not made by bonding one batt to another batt.

The core is formed mainly by fibers from the central part of the wadding, while the outer parts of the core are united in a zone formed from the same fibers on the first and second opposite sides.

By varying at least two of the fiber-forming parameters, the fibers and other properties of the quilt can be controlled. As we have pointed out, the important fiber properties are mainly the yield (grams of mineral matter per unit area), especially if the quilt is to be as uniform as possible, but changing the yield usually causes changes in the fiber properties unless some parameter is changed to compensate.

By varying two or more fiber forming parameters, it is possible to control the fibers and other properties along the web. As indicated, the important fiber properties are mainly the yield (grams of mineral matter per unit area), especially if we want the web to be as uniform as possible, but changing the yield will normally result in a change in the fiber properties unless another parameter is changed to compensate.

The purpose of varying two or more fiber formation parameters is to achieve different properties, such as the average fiber diameter—average

:.............. • · · · · ·· «*♦ properties in terms of fiber length, amount of material fed or chemical composition. In this way, the quilt may have an AB configuration or an AA—B or ABA or ABC configuration and similarly, the batting may have such configurations along its thickness.

The average fiber diameter of the core portion of the batt and/or the center portion of the quilt may differ from the average fiber diameter of a face. For example, the average fiber diameter of the core portion may be less than 90% or more than 110% (e.g., 20-90% or 110-200%) of the average fiber diameter of the face.

Instead of or in addition to the fiber quality appearing in the differences in fiber diameter, the difference may also appear in the fiber length, and the fiber length of the core part of the batt and/or the middle part of the quilt may be less than 90% or greater than 110% (for example, 50-90% or 110-200%) of the fiber length on the front side.

It is often advantageous if the average fiber diameter and/or filler content of the core portion is at least 10% (typically 20-60%) less than that of the face portion or both, and if the filler content and/or fiber length of the face portions is at least 10% (typically 20-60%) less than the length of the fibers of the core portion. This gives the core optimal insulating properties (by maximizing fineness) and allows for optimization of strength and other properties in one or both face portions (by maximizing fiber length). In other words, the fiber length of the core portion is at least 10% less than that of the face portions.

Another difference in fiber quality is the tensile strength of the batt. This can vary along the thickness of the batt, with the core typically having a strength less than 90% or greater than 110% of the face strength (typically 50-90% or 110-150%).

Differences in fiber quality, on the other hand, are reflected in the density. Density is the total mass of material collected in the batt and core per unit volume. The output of one of the spinning devices is typically at least 5% more or less than the output of one or more of the other spinning devices, even if they are of essentially the same construction and operation in theory, and this can result in a change in density.

Each face, having a specified fibre quality, constitutes at least 5% of the thickness of the batt, extending inwards from the outermost surface and the core section (if different), constituting at least 20% of the thickness. There is a transition in the properties between the sections, for example the face section and the core section. Often each face accounts for at least 10% of the thickness, but usually not more than 30-40% if there is a separate core section. The core section (if present) may be 80% of the thickness if the face sections are thin, but often not more than 30 or 40%.

The melt may be any mineral melt that can be formed into fibers, such as glass, slag or rock. Often it is a slag or rock that has, for example, an alkaline earth metal oxide content of more than 15% by weight and an alkali metal oxide content of less than 10% by weight. It may be, for example, a conventional slag or rock melt or a high aluminum content melt such as that described in WO 96/14274 or a low aluminum content melt such as that described in the prior art in WO 96/14274.

Binder and other additives may be added to the fiber cloud in known manner. The amount of binder or other additive may be the same or different on each spinning apparatus.

The batt may be of any conventional shape, such as a braid or sheet and the crosslinking of the binder, which may be cut and/or formed (e.g. into pieces).

The products made according to the invention can be formed into any conventional MMV fiber product, such as sheets, plates, tubes or other shaped products, which can be used for thermal insulation, fire and sound insulation or reduction and control, or can be formed into a horticultural growing medium or into a shape for reinforcing cement, plastic or other products.

The invention is illustrated in the accompanying drawings, of which:

Figure 1 is a perspective view of an apparatus suitable for the purpose of the invention, Figure 2 is a perspective view of a draining device which serves to feed the three cascade spinning devices according to Figure 1, Figure 3 is a vertical sectional view of the resulting wadding, Figure 4 is a perspective view of another apparatus which can be used according to the invention.

Referring to Figure 1, the three cascade spinning apparatuses 1, 3 and 2 have rotors 4 from which the fibers are centrifugally dispersed in the usual manner. The fibers from the spinning apparatus 1 are collected on the blanket 7 on the conveyor belt 5 in the wind region R1, while from the spinning apparatus 2 mainly along the opposite wind region R2, and from the spinning apparatus 3 mainly along the central region R3. The regions R1 and R3 merge with each other in the diffusion zone 6, and the regions R2 and R3 similarly in the diffusion zone 6.

If desired, a binder or other material other than MMVF can be advantageously sprayed from one or more spinnerets, for example only through spinneret 3, so that the central region R3 has a significantly higher concentration of additive than the regions R1 or R2.

The quilt 7 is then overlapped by a pendulum overlapper 8 and the cross-lapped product is a wadding collected on the conveyor belt 9.

The batt (see Figure 3) has an upper face 10, formed mainly by the R2 region of the quilt, and a central core 12, formed mainly by the R3 region of the quilt.

The front and core parts 10 and 12, and the front and core parts 12 and 11, are united with each other in an indefinite zone 13 and are integral with each other.

Figure 4 is a rear view of a device similar to the device shown from the front in Figure 1, except that it also shows the corresponding conduit. This conduit may be as described above with reference to WO 96/38391.

Thus, the chamber 50 is essentially oval and takes the shape of the cylinders 3 *·λ '· • ' *·* ♦% which merge with each other and surround the spinning devices 1, 3 and 2. A single, vented oval housing 51 leads to it, which defines the sides and top of the spinning chamber. The rest of the apparatus is as shown in Figure 1. The blanket 7 may be, for example, 2 to 6 meters (often about 4 meters) wide.

Referring to Figure 2, the drip device used to feed the melt into the spinning apparatuses 1, 3 and 2 is shown in Figure 2, in which the shaded portion illustrates the melt flow.

The drainer consists of a T-shaped drainer 20 having a base or arm 24 extending forward to a discharge 23 which discharges the melt into the spinner 3. This has side arm portions 25 and 26 extending transversely from a point 27 where the melt 28 flows down into the drainer. Side arm 25 leads into the discharge portion 21 to discharge the melt into the spinner 1, while arm 26 leads into the discharge portion 22 to discharge the melt into the spinner 2.

The plate 29 bridges the rod portion 27 and defines the lowermost opening 30 through which the melt can flow along the rod 24 and is rigidly attached to the arms 25 and 26 and to the rod 24 as a unitary, rigid assembly of the T-shaped device, the arm base and arm drains, and the plate 29.

The entire dripper assembly is mounted on a substantially horizontal axis, as shown by line 31, with bearings 32 on a fixed housing. The bearings 32 are connected by rods to an arm 33 which is attached to the plate 29 at a bearing 34 and which is actuated (to oscillate about the axis 31) by a control piston 35 which is attached to a fixed point 36. Accordingly, the extension or retraction of the piston 35 oscillates the dripper assembly about the horizontal axis 31.

Another control piston 37 is connected to the plate 29 by a bearing 38 and a pivot 39 to the rod 33. Therefore, the extension or retraction of the piston 37 will cause the dripper to oscillate about the axis shown by line 40, which is substantially horizontal and substantially perpendicular to the axis marked by line 31.

Accordingly, the control pistons 35 and 37 can be used to independently control the vertical position of the stem 24 and the open ends of the arms 25 and 26 relative to each other, thereby enabling the flow rate of the melt at each of the discharge points 21, 22 and 23 to be controlled independently.

The novel products of the invention can be analyzed for the difference between the core and one or both of the facings, regardless of the specific technique used to determine the properties of the core and facings. For example, it can be determined whether a product has an adequate difference in average fiber diameter by using any conventional method for determining average fiber diameter for the core material and the facings, provided that the same method is used in both cases. Similarly, any conventional method for determining average fiber length can be used to compare fiber length values. Similarly, any conventional method can be used to compare filler content (greater than 63 μm) and to compare tensile strength values.

Similarly, any conventional method can be used to compare density values, particularly mass per unit volume.

Similarly, any conventional method can be used for chemical analysis of the fibers.

In all cases, the cotton wool to be analyzed should be sliced parallel to its front side to obtain representative samples of the front sides and core parts, and the analysis should be performed on these samples.

Examples of the invention are described below.

In each of the following examples, the apparatus comprised three cascade spinnerets, each of which had four rotors arranged side by side, on which the melt flow could be controlled independently, as described above with reference to the drawings.

Each of the rotors was interchangeable, and their relative spaces and acceleration fields could be adjusted by varying the diameter and/or rotational speed. The first rotor was always 100-250 mm in size, the second 250-300 mm, and the third and fourth rotors 250-400 mm in size. Each of the three spinnerets, placed side by side, was supplied with a primary air flow, and the fibers from the spinnerets were conveyed forward and collected in a spinning chamber 2.5 or 4 meters wide.

The rotors and their rotation speeds were chosen to provide 4 different acceleration fields, which are designated below as modes A, B, C and D.

Mode A, km/sec ² Mode B, km/sec ² Mode C, km/sec ² Mode D, km/sec ² front rotor 40 60 75 120 second rotor 40 76 150 220 third rotor 80 120 200 320 fourth rotor 95 130 270 350

In each of the following examples, the results are tabulated. The melt flow is the amount of melt fed to the first rotor of each spinning apparatus in tons per hour. The primary air is the air that flows out of slots located directly adjacent to the circumference of each rotor and the secondary air flow is the air that is blown out of slots located elsewhere, not directly adjacent to the rotors.

The slots around the circumference of the fourth rotor are equipped with a stator consisting of blades arranged at different angles, as described in WO 92/06047. The values marked DE are the values of the DE angles shown in Figure 1 of WO 92/06047, while the values marked EF are the values of the EF angles shown in Figure 1 of this patent, in each case on the fourth rotor. However, it may be advantageous to use the same variation around the third rotor.

The combustion loss is determined by combustion in the usual way.

Example 1

The spinning devices are adjusted relative to each other to meet the following parameters.

Spinner No. 1 Spinning device number 3 Spinning device number 2 melt flow 3.5 t/hour 5 t/hour 3.5 t/hour melt temperature 1500-1520°C 1500-1520°C 1500-1520°C acceleration field The way Mode C Mode B primary air speed 80 km/sec ² 120 km/sec ² 80 km/sec ² primary air volume 5500 ^m3 /hour 7500 ^m3 /hour 5500 ^m3 /hour secondary air volume 2000 ^m3 /hour 5000 ^m3 /hour 2000 ^m3 /hour stator angles DE 0-18° EF 18-27° DE 0-24° EF 24-42° DE 0-18° EF 18-27° combustion loss 2.2% 1.8% 2.2%

This product is an optimal quality low-density product with good compression and insulation properties, belongs to the lambda 040 class, and has a density of 28 kg/m ³ .

Example 2

In this example, the parameters were set as follows:

Spinner No. 1 Spinning device number 3 Spinning device number 2 melt flow 4 t/hour 4 t/hour 4 t/hour melt temperature 1500-1520°C 1500-1520°C 1500-1520°C acceleration field The way Mode B The way primary air speed 100 km/sec ² 120 km/sec ² 100 km/sec ² primary air volume 7500 ^m3 /hour 7500 m7 hours 7500 ^m3 /hour secondary air volume 4000 ^m3 /hour 4000 ^m3 /hour 4000 ^m3 /hour stator angles DE 0-18° EF 18-27° DE 0-24° EF 24-42° DE 0-18° EF 18-27° combustion loss 4.2% 3.3% 4.2%

This product is a heavy product with both sides resistant to pressure.

Example 3

The equipment was set up as follows.

1. spinning device with number s Spinning device number 3 Spinning device number 2 melt-flow 5 t/hour 4 t/hour 3 t/hour melt temperature 1500-1520°C 1500-1520°C 1500-1520°C acceleration field The way Mode B Mode B primary air speed 100 km/sec ² 120 km/sec ² 100 km/sec ² primary air volume 7500 ^m3 /hour 7500 ^m3 /hour 7500 ^m3 /hour secondary air volume 4000 ^m3 /hour 4000 ^m3 /hour 4000 ^m3 /hour stator angles DE 0-18° EF 18-27° DE 0-24° EF 24-42° DE 0-18° EF 18-27° combustion loss 4.2% 3.3% 3.0 %

This product is a heavy, pressure-resistant product on its surface, but with a flexible side that can absorb the irregularities of the surface on which the product is to be installed, for example a ceiling tile. By choosing the parameters, a systematic uneven distribution of the yarns in the wadding can be achieved, resulting in a distribution in the final product in which the upper third is denser than the rest of the product. Asymmetrical strengths along the thickness of the product can be achieved by varying the amount of binder in such a way that the maximum amount of binder is in the upper layer (containing the fibers of maximum length) and the minimum amount of binder in the lower layer, which is made up of flexible and finer fibers.

If desired, further variations in thickness, for example in density and strength, can be achieved by subjecting the product to conventional treatments.

The spinneret conditions are set such that the highest melt flow is applied to the middle spinneret and the highest acceleration field and primary air volume are also applied to the middle spinneret.

Spinner No. 1 Spinner No. 3 Spinner No. 2 Melt flow 2.5 t/h 7 t/h 2.5 t/h Melt temperature 1500-1520°C 1500-1520°C 1500-1520°C Acceleration field Mode A Mode C Mode B Primary air speed 80 km/sec ² 120 km/sec ² 80 km/sec ² Primary air volume 5500 m ³ /h 7500 m ³ /h 5500 m ³ /h Secondary air volume 3000 m ³ /h 4000 m ³ /h 3000 m ³ /h Stator angles DE 0-18° EF 18-27° DE 0-24° EF 24-42° DE 0-18° EF 18-27° Combustion loss 1.2% 1.8% 1.2%

Claims (27)

PATENT CLAIMS 1. Equipment for the production of MMVF wadding, consisting of: a first and second centrifugal spinnerets (1 and 2) arranged substantially side by side and optionally one or more (3) third devices between the first and second spinnerets, each centrifugal spinneret comprising at least one spinning rotor rotating about a substantially horizontal axis, the or each rotor providing an acceleration space, means for feeding the MMVF melt to each of the spinnerets, means for entraining the fibers from each of the spinnerets in an air stream around the spinning rotor of each spinneret (4), the air stream having a flow space, and thus forming a single cloud of fibers entrained in air, a permeable conveyor belt (5) for collecting the fibers into a web having opposing first and second edge portions (R1 and _R2 ) and a central portion (R3), and means for removing the fibers from the cloud air is drawn through the conveyor belt, whereby the first and second spinning devices form the fibers that provide the first and second edge portions, respectively, and means for cross-plying the batt to form the batt, wherein the first end portion of the batt is formed mainly from the first (10) edge portion of the batt, the opposite second end portion is formed mainly from the second edge portion of the batt, and a core portion of the batt is formed between the first opposite, first and second end portions of the batt, characterized in that one or different device(s) has means for selecting two or more fiberization parameters, wherein these parameters are: (a) the physical properties or chemical composition of the melt fed to the spinning device, (b) the rate of feeding the melt to the spinning device, (c) the positioning of the fiberizing rotor or at least one of the fiberizing rotors on a spinning device for that purpose feed! relative to the location at which the melt is fed to that spinner, (d) the acceleration range or ranges of that spinner, and (e) the flow area of the or each air stream associated with a spinner. 2. A method for producing MMVF wadding, comprising centrifugally forming fibers from a mineral melt by feeding the melt into first and second centrifugal spinners (1, 2) arranged substantially side by side and optionally one or more spinners between the first and second spinners, each centrifugal spinner comprising at least one spinner rotor (4) rotating about a substantially horizontal axis, each rotor providing an acceleration field, entraining the fibers from each spinner into an air stream around at least one spinner rotor, the air stream having a flow field and thus forming a cloud of fibers in the air, collecting the fibers on a permeable conveyor belt (5) into a blanket (7) having first and second opposite edge portions (R1 and _R2 ) and a central portion (R3), such that the cloud is passed through the conveyor belt the air is extracted, whereby the first and second spinning devices form the fibers that predominantly form the first and second edge portions and the batt is overlapped, thus forming (8) a wadding, the first front side portion (10) of which is mainly formed by the first edge portion of the batt and the opposite second front side portion (11) of which is mainly formed by the second edge portion of the batt and the wadding also has a core portion between the first and second front portions, characterized in that the centrifugal spinning is the selection of two or more spinning parameters of one or more spinning devices, such as (a) the physical properties or chemical composition of the melt fed to a spinning device, (b) the selection of the flow rate of the melt to the spinning device, (c) the selection of at least one of the spinning rotor or rotors on a spinning device - the feeding of the melt to this spinning device! (d) the acceleration field or fields of a spinneret and (e) the flow field of the air stream or each air stream relative to a spinneret can be independently controlled by independent selection of the spinneret, and wherein at least two of the fiberization parameters are adjusted before or during the production of the MMVF batt to vary one or more of the batt edge or batt core properties, such as (1) average fiber diameter, (2) average fiber length, (3) fill content, (4) tensile strength of the fibrous material, (5) bulk density, or (6) chemical composition. 3. The method of claim 2, wherein a third centrifugal spinner is used between the first and second spinners. 4. The method of claim 2 or 3, wherein each spinner is a cascade spinner comprising a first rotor rotating about a substantially horizontal axis and at least one further rotor rotating about a substantially horizontal axis, which is arranged to receive the melt discharged from the first rotor and discharge it in the form of fibers. 5. The method of claim 4, wherein one of the spinners is provided with an air stream at least in part by providing a primary air stream that substantially contacts a portion of at least one or all of the further rotors, optionally also a second air stream that flows around the primary air stream. 6. The method of claim 5, wherein the primary air flow exits from guide elements disposed on the periphery of each of the other rotors and arranged to direct the air flow substantially parallel to the rotor surface and at an angle of 5-60° thereto. 7. The method of claim 6, wherein the directing means on the or each of the third spinning apparatus directs the air flow at an angle that is at least 20° and at least 5° greater at at least some parts of the spinning apparatus than at corresponding parts of one of the other spinning apparatuses. 8. A method according to any one of claims 4-7, wherein the acceleration field on some or all of the further rotors of the one or each spinning device is at least 10% greater than the corresponding acceleration field on the other rotor or rotors. 9. The method according to any one of claims 2-8, wherein the amount of melt fed to one of the spinnerets is at least 10% more than that fed to one of the other spinnerets. 10. The method of any one of claims 2-9, wherein each of the spinning devices is arranged side by side in a substantially oval-shaped channel. 11. The method of any one of claims 2-10, wherein varying the edge and/or core properties of the batt by selecting the fiberization parameters results in providing a batt having the same properties across its width. 12. The method of claim 11, wherein the variation of the quilt edge portion or quilt core portion properties is a yield variation, thereby obtaining a quilt having a uniform mineral content along its width. 13. The method of any one of claims 2-10, wherein at least two of the fiber forming parameters are varied by changing the quilt edge portion and/or quilt core portion and the batt edge portion and/or batt core portion to form an A-B, A-A-B, A-B-A or A-B-C configuration. 14. The method of claim 13, wherein the average fiber diameter in the quilt portions and batt sections is at least 10% smaller than the average fiber diameter in at least one other quilt portion and batt section. 15. The method of claim 13, wherein the average fiber length in at least one of the batt sections and quilt sections is at least 10% less than the average fiber length in at least one of the other batt sections and quilt sections. 16. The method of claim 13, wherein the fill content in at least one of the wadding sections and quilt sections is at least 10% less than the fill content in at least one of the other wadding sections and quilt sections. 17. The method of claim 13, wherein the chemical composition of the fibers in at least one of the batt sections and quilt sections differs by at least 2% for one element from the chemical composition of at least one of the other batt sections and quilt sections. 18. An integral MMVF batt having a first face portion (10) extending inwardly from one face portion, a second face portion (11) extending inwardly from the opposite face portion, and a core portion (12) between the first and second face portions, wherein the sections are integral with each other and at least one fiber property of one section differs from the fiber properties of at least one of the other sections, and wherein the property is selected from the group consisting of average fiber diameter, average fiber length, fill amount, density, and chemical composition of the fibers. 19. The wadding of claim 18, wherein the average fiber diameter in one section is at least 10% smaller than the average fiber diameter of the fibers in at least one of the other sections. 20. The wadding of claim 18, wherein the average fiber length in one section is at least 10% less than the average fiber length of the fibers in at least one of the other sections. 21. The wadding of claim 18, wherein the fill content in one section is at least 10% less than the fill content in at least one of the other sections. 22. The wadding of claim 18, wherein the chemical composition of the fibers in at least one of the sections differs by at least 2% of one element from the amount of at least one of the elements in the fibers in at least one of the other sections. 23. Apparatus for forming a synthetic glass fiber mat comprising first, third and second centrifugal spinnerets (1, 3, 2) arranged side by side, a rigid dripper (20) for receiving melt at a feed location (28) and for feeding melt from first, third and second discharge locations (21, 23, 22) to the first, third and second spinnerets (1, 3, 2), respectively, and wherein the dripper has first and second dripper arms (25, 26) extending generally in opposite directions toward the first and second discharge locations away from the receiving location, and a third arm (24) extending generally forward of the third discharge location, and means for independently tilting the dripper about a generally horizontal axis extending generally transversely and substantially horizontally. tilting about an axis extending generally forwardly, wherein the melt flow rate at each of the first, second and third locations can be controlled independently of the melt flow rate by independent tilting of the troughs. 24. The apparatus of claim 23, wherein the dripper is substantially T-shaped, the base of the T extending forwardly and the dripper is mounted for oscillation about a substantially horizontal axis substantially parallel to the base of the T and for independent oscillation about a substantially horizontal axis substantially parallel to the base of the T. 25. The apparatus of claim 1, comprising means for independently selecting the or each air stream of one spinner relative to the or each air stream of another spinner. 26. The apparatus of claim 25, wherein the selection results in the air flow direction on one spinning device and the air flow direction on the corresponding other spinning device differing by at least 5°. 27. The apparatus of any one of claims 1, 25 and 26, wherein each spinning device is mounted independently of all other spinning devices. The authorized person: Katy Berzsi? Office of the Central Data Protection Office, Η -1062 Budapest, Andrássy út 113 Tetei fv 34-24-950. Fax: 34-24-32.·