SE464706B - SETTING TO BRING BINDING TO MINERAL WOOL - Google Patents

Description

464 706 air currents around the spinning wheels. The air streams have several tasks, among other things to carry the fibers away from the fiberizing means themselves and towards the collecting means, whereby, as mentioned above, the fibers are deposited on the collecting means, while the gas or air stream passes through.

In commercial processes for the production of mineral wool products, there is in principle this air or gas stream, in which the newly formed fibers are more or less well suspended, and which stream carries the fibers from the fiberizing device to the receiving means. If binder is now to be added to the mineral wool, which is practically always the case, the application takes place in most cases by adding a finely divided binder to this fiber suspension.

Instead of binders, or in combination with binders, other additives can in principle also be made, for example of wetting agents or dust binding agents. The supply often takes place very close to the fiberizing member itself. The reason why the binder is conveyed to the fiber suspension and not to the continuous web formed on the receiving means is that it is difficult to get binder to penetrate into a mineral fiber structure due to the density of the structure and the fineness of the fibers in relation to the size of the binder droplets.

There are two mainly different principles for the work of the reception body. According to one principle, the one that was originally used, a final path is built up on the conveyor of the receiving means which then goes on to hardening, cooling, dividing, cutting, etc. In technical terms, this means that the basis weight, eg ig / mzm, already at the first deposit on the permeable conveyor of the receiving means is the same as that which is to be present in the final product. However, there is another principle that in many cases gives a better result. According to this principle, a relatively thin web is first collected, a so-called primary web, which is then, through a folding procedure in one or more steps, allowed to build up a final web whose basis weight corresponds to the basis weight of the finished product. The basis weight of the primary F web can in many cases be much smaller than the final web, for example one tenth or less. The air or gas flow which carries the fibers from the fiberizing device to the receiving means is more or less turbulent.

However, investigations have shown that, especially when the distance is not particularly long, no complete mixing takes place. This means that fibers which are introduced into this air or gas stream at one point tend to settle substantially at a certain place or within a certain area of the receiving conveyor, while fibers which are introduced into the air or gas stream at another point substantially located in another area. This discovery has been utilized in the creation of the present invention.

It is now the case that the binder used in mineral wool products is usually of an organic nature. Almost exceptionally, a phenolic plastic is used, which may, however, be more or less modified.

However, the mineral wool itself can withstand higher temperatures than the organic binder does. For certain areas of use, for example as insulation in stoves or ovens, you will then have two disadvantages, both of which are related to the binder not being able to withstand the temperature that occurs.

One of these disadvantages is that gases and smoke are generated when the binder is burned off, and this causes, among other things, odor problems. The second disadvantage is that the binder-free wool afterwards does not have the firmness that the application may require. This has led to a search for more temperature-resistant binders, preferably inorganic ones. However, it is very difficult to find an inorganic binder that can give the products the same elasticity and dimensional stability as the plastic binders. In addition, most require the introduction of significant amounts of water. This in turn causes drying problems. Most plants for the production of mineral wool are adapted for the use of a plastic binder that can be fixed in a very short time in the so-called hardening furnaces. If a water-based, inorganic binder is now introduced, the curing ovens will not suffice, but the ovens will either have to be expanded or production capacity reduced considerably. As an alternative, it has then been intended to first manufacture a phenolic resin-bonded mineral wool product and later treat it, at least on the side to be exposed to high temperature, with an inorganic binder which is then pressed or sucked into the product. However, this means that you get an additional production process.

The invention is based on the discovery that there is a certain 464 706 correspondence between a point at the beginning of the fiber suspension on its way to the receiving means and a larger or smaller area on the surface of the receiving means with a certain part of the fiber suspension as it is at the beginning of its path. Correspondingly, a certain part of the surface of the receiving means can be interconnected with a certain part of the final product. This is used according to the invention so that different parts of the fiber suspension are supplied with binders or binder mixtures of different types and possibly with different dosages so that different layers in the finished web or product will contain different binders or binder mixtures and possibly also different binder contents.

It is particularly interesting to be able to give one or both surface layers of the product altered properties in this way. Examples have already been mentioned above. Other examples of such properties that can be changed by providing a surface layer with another adhesive are paint, dust, water repellency or water absorption.

According to the invention, however, it is also possible to influence the second outer layer by also adding another binder thereto.

The surface layer or layers thus changed by special additives may also contain the same binder as the rest of the product, the main binder. If both surface layers have been provided with special additives, the nature and content of the additive as well as the thickness of the layers may be the same or different.

In cases where the final web is formed on the receiving means, in a step from a fiber suspension which in the initial stage moves substantially horizontally and which is deposited on a horizontal or obliquely upwardly inclined conveyor, so-called long-chamber process, it is usually the upper part of the fiber suspension adjacent the fiberizing device which also forms the upper part of the final web, i.e. the upper outer layer of the product. Correspondingly, it is usually the lower part of the fiber suspension which is deposited on the receiving means as the lower layer of the final web. The second outer layer of the product.

In the cases where the final web is built up by a plurality of fibrous means one by one depositing its fibers on the receiving means, it is the case that the first fibrillating means substantially forms the lower layer of the final web and the last means forms Jb and : -.1 C øw the upper layer.

In cases where the final web is formed by joining one or more thinner webs, primary webs, there is a connection between the edges of the primary web and the upper and lower layers of the final product, respectively. It is then possible to assign to the part of the fiber suspension which settles in one edge of the primary web a special additive instead of, or in addition to, the main binder. The additive will then end up in the top or bottom layer of the final web, depending on which edge of the primary web is treated there.

It has been found that an improved effect is obtained by compressing the primary web edge thus treated. This can suitably be done with a roller or roller which presses against the primary web from the edge and a distance towards the middle, preferably 10 cm.

Correspondingly, one can identify the part of the fiber suspension that mainly builds up a certain part of the product and add a special binder or other additive to this part. One can, if the addition to a certain layer is another binder, to this part either maintain the addition of the main binder to the layer or refrain from it. As a rule, however, it is appropriate to allow the main binder to be present throughout the final web, even if other binder is applied to a certain or certain layers.

The invention will now be described in more detail with the aid of Figures 1-6. In the drawings, Figure 1 shows a side view of a plant for producing a mineral wool mat in one step. Figure 2 shows a detail, seen from behind, at an installation for the production of a mineral wool mat by folded laying, and Figure 3 shows the same installation seen from the side. Figure 4 shows a modified plant from the production of a mineral wool mat. Figures 5a and 5b diagrammatically show the direction of advance of the mineral wool mat cross-section through five different portions of the mineral wool mat in two different alternatives, and figure 6 schematically shows a side view a further alternative embodiment of a plant according to the invention for producing a mineral wool mat.

Figure 1 schematically shows the lower part of a melting plant 1 and melt which continuously flows out through groove 2 down onto the spinning wheel 3 in the form of a jet 4. 464 706 The melting plant can be of several different types and has therefore only been indicated. The spinning wheel 3 is driven by a shaft 5 enclosed in a housing 6. An air stream 7 flows around the spinning wheel 7. The air flow is present around the spinning wheel but has for the sake of clarity only been shown on the underside. When the melt from the melt jet 4 hits the spinning wheel 3, it wets on it but is thrown out due to the centrifugal force and forms fibers 8. The fibers are thrown out in the plane of the wheel but their path is bent by the air flow 7.

The fibers are transported by the air stream towards the collecting belt 9, for example a perforated steel belt, which runs in the direction 10 over the rollers 11 and 12. Behind the steel belt there is a suction box 13, in which a negative pressure is created by a fan system. The fibers are deposited in the form of a mat 14, which is removed by the belt 9 as the arrow 15 shows.

Fig. 2 shows how a thicker mat is formed by folding a thinner mat. In the figure, 16 denotes a thin mat produced, for example, as the mat 14 in figure 1. The mat 16 is advanced on a belt conveyor 17 up to a so-called pendulum. The pendulum consists of two belt conveyors 18 and 19 between which the mat 16 'is moved substantially downwards.

The conveyors 18 and 19 are pivotally mounted at their upper end, while the lower end moves rhythmically back and forth over a transverse receiving conveyor 20, which moves at a much lower speed than the conveyors 17, 18 and 19. The carpet will thereby deposit in bays 21.

Fig. 3 shows the same in simplified form seen from the side. The mat 16 moves downwards as the arrow 22 shows between the conveyors 18 and 19 not shown in the figure. It is then laid on the conveyor 20 in bays 21, which will partially cover each other as Figure 3 indicates. One edge portion of the primary web will form one surface layer of the new web while its other edge portion will form the second surface layer.

The mat, which is now formed by the bays 21, will, thanks to the properties of the mineral wool web 16, form a substantially continuous, though substantially thicker web than the mat 16. It then proceeds to plants for compaction and hardening of the binder, etc. .

Figure 4 shows, in principle, a plant for formation and _121- ON -Fn sa CD Oh collection of a mineral wool web. From a smelting plant 24, the melt flows down into a divided melting chute 25 and is thus distributed to two spinning wheels 26 and 262. A part of the melt is transferred secondarily to the spinning wheel 27 and 27, respectively. 272 The spinning wheels rotate rapidly using drive shafts not shown in the figure. From the spinning wheels, the melt is ejected in the form of fibers, which by the action of the air currents 28 and 28 ', which surround all the spinning wheels, are advanced towards the receiving belt 29, as the arrows A, B, C, D and E show. Binders are emitted from the so-called center diffusers 30, 31, 32 and 33, which hit the fiber streams A-E. Fibers depart from different points on the periphery of the spinning wheel. Only those which move in the horizontal plane through the spinning axles are shown in the figure. A stream of binder 34 from a nozzle 35 is directed towards the fiber stream A, which is fed via the line 36. A binder stream 37 is directed towards the fiber stream E, which flows from the channel 38, which opens into the opening 39 in the wall 40. The binder stream 37 is generated by a nozzle 41 , which is fed with binder through line 42 and compressed air through line 43.

The fiber streams A-E move towards the collecting belt 29 through the negative pressure which is generated via a suction box (not shown) on the back or underside of the collecting belt. The fiber stream A then ends up mainly at the area F on the belt, the fiber stream B at the area G, etc. It is then noticed that no exact demarcation between the fiber streams occurs. Normally there is always some turbulence, which means that the fiber streams mix with each other without sharp boundaries.

Between the areas F and G on the belt thus ends up a mixture of fibers from the fiber streams A and B etc.

All means for adding binder, the center spreaders 30, 31, 32 and 33, the nozzle 35 and the nozzle 41 can now be fed separately, thereby delivering separate types of binder with individual dosing. Normally, the center diffusers are fed with the main binder, which is usually a phenolic resin. Through rear-acting nozzles such as 35, it is advantageous to add suspensions of inorganic binder, for example bentonite suspended in water. Due to the intense heat from the melting of the spinning wheel, evaporation of water takes place already at an early stage, which reduces the need for drying afterwards without disadvantaging the atomization process. If, on the other hand, one wishes to add a substance, for example an organic dye which is heat-sensitive, this is advantageously done in a nozzle such as 41, where the addition itself and the atomized substance, represented by 37, are spared from too high a temperature.

If in an arrangement, as shown in Figure 4, the main binder is dosed from the center spreaders 30-33, and another binder is supplied from the nozzle 35 and still another substance from the nozzle 41, the amount of binder shown in Figure 5a can be obtained along its horizontal axis. in different positions in the width direction of the collecting belt.

The letters F, G, | l, I and J correspond to approximately the positions found in figure 4. The amount of additives to the mineral wool has been marked on the vertical axis. The significance of the markings can be found below the figure. If all the center spreaders 30-33 are dosed in the same way and with the main binder, the main binder deposit will be relatively evenly distributed in the entire mineral wool mat.

In the example another binder has been added through the nozzle 35 and this is found as an addition to the main binder substantially at position F with some spread towards position G. The additive, in the example a dye, which is added via nozzle 41, is found in position J with any pulling to position I.

Figure 5b shows the same example, but there the center diffusers 30 and 33 have significantly less dosage than the center diffusers 31 and 32.

On the other hand, the nozzles 35 and 41 are fed with larger amounts than in the previous example. This means a completely changed distribution of additives to the mineral wool, as Figure 5 b also shows.

It is easy to see that in this way a virtually unlimited number of variants can be achieved. For each specific area of use, where only one main binder is not sufficient to give the products the desired properties, a dosing characteristic can be set up which satisfies the needs.

Figures 5a and 5b show only the amounts within each part of the mineral wool mat. It should not be understood that the main binder is separated from the other binder. In fact, within the area F, both the main binder and the other binder are present throughout the carpet. Similarly, in the area J, the main binder and the second additive are present throughout the carpet.

.Bm O “\» Fi -: | CD CJ \ The diagrams show only the relative quantities.

Of course, it may be required that a nozzle, corresponding to the nozzle 35, is also found on the other side so that the fiber flow at E may also receive additives from such a nozzle. Likewise, a nozzle corresponding to the nozzle 41 may be needed on the other side in order to thereby influence the fiber flow A and the position F. Correspondingly, nozzles corresponding to the nozzle 35 can be placed in different positions relative to the fiberizing plant, not only at the flanks.

Figure 6 shows an application of the invention to a so-called long-chamber line. The fibrous stream 8 with adhesive 44 is carried by the air stream 7 over the sill 45 into the chamber 46. There it falls and is sucked down towards the belt 47, under which a suction box 48 is arranged. The belt 47 runs over, among other things, the roller 49, which partially projects below the threshold 45. The belt moves in the direction of the arrow 50, and more and more mineral wool is deposited on the belt so that the thickness increases towards the chamber outlet 51, where sealing against the chamber gable 52 takes place with the chamber roller. 53. It can be seen that the upper part 54 of the outgoing mineral wool layer essentially originates from the fibers entering the chamber 46 near its roof 55, while the part of the mineral wool layer closest to the belt 47 originally comes from the lower part of the fibrous assembly. and flows into the chamber near the threshold 45. If you want to add another binder to one of the surfaces of the product, you advantageously choose to do so in the underside. In this case, this second binder is supplied via the nozzle 57 fed from the line 58. The stream of binder particles which then leaves the nozzle 57 hits the lower part of the fiber plume 44 and ends up, as mentioned above, in the lower part of the product.

The nozzles 35, 41 and 57 have been referred to in this description as single nozzles. However, there is nothing to prevent, and it is often convenient, to use several nozzles instead of one nozzle, so that the binder additive does not become too concentrated in a single area.

As an example of the use of the invention, an experiment is described here which connects to machine set-ups according to Figures 1, 2, 3 and 4. At a production quantity of 4,000 kg / h, 30-33,250 l / h in each nozzle were sent through the center nozzles. Through the nozzle 35 was sent 1,600 l / h of a bentonite sludge with 7% dry matter content. The main binder consisted of a phenolic resin with a dry matter content of 464,706 cza 20%. This gave a binder yield through the product of about 3.5% by weight based on phenolic resin. Bentonite was abundant in the upper layer of the product. The exact amount, however, was difficult to determine. the products had excellent high strength and even after the bentonite-coated side was exposed to temperatures of 400 °, when the phenolic resin was rapidly burned off, the product still had sufficient high strength properties to be handled.

In a reverse experiment, through the center nozzles 30-33 1,200 1 / h per nozzle of bentonite sludge was passed through, while from three nozzles 35 spaced over each other, phenolic resin was sent in an amount of 200 1 / h. The mineral thus impregnated could only be cured with some difficulty. After curing and drying, however, it had satisfactory properties in terms of strength. This was also the assessment since the side which did not contain phenolic resin had been exposed to a temperature of 500 ° C for 10 hours. Prior to heat treatment, it was found that one side provided with phenolic resin had a significantly better handling strength than the side where only bentonite was the binder. After the heat treatment, the strength properties of the product were satisfactory.

Claims (9)

464 706 '11 P a t e n t k r a v By means of a plurality of distribution means, for example nozzles or diffusers (30-33, 35, 41; 57), add binders to newly formed mineral wool fibers while they are suspended in an air or gas stream (7; 28, 28O and on the way to a collecting device (29; 47), which in one or more steps forms a final mineral wool web, characterized in that binders or binder mixtures of different kinds and possibly with different dosages are added to different parts of the fiber suspension so that different layers in the finished web will contain different binders or binder mixtures and possibly also different binder contents. 2. A method according to claim 1, characterized in that the part of the fiber suspension, which essentially forms the top or bottom layer of the final web, is added by means of one or more special distribution means, binders of a different kind than the binder, the main binder, which is applied to the part of the fiber suspension which essentially forms the rest of the final web. 3. A method according to claim 1, characterized in that the parts of the fiber suspension, which essentially form the two outer layers of the final web, are applied by means of one or more special distribution means, adhesives of a different type than the adhesive, the main adhesive, which is applied to it. part of the fiber suspension which essentially forms the rest of the final web. Method according to one of the preceding claims, characterized in that the mineral wool fibers are first collected into a thin web, the primary web (16), which is later joined together, for example by folding, into a thicker, final web (21), so that one edge of the primary web forms the upper layer of the final web and the other edge forms its lower layer, and in that the part or parts of the fiber suspension which form one edge or both edges of the primary web are supplied with a binder other than that which is added to the suspension in general.a 464 706 H A method according to claim 4, characterized in that the edge or edges (s) containing the adhesive other than the main adhesive are compressed, for example with a roller or roller, before the primary web (16) is combined into a final track (21) Method according to one of the preceding claims, characterized in that a binder other than the main binder is supplied to the part of the fiber suspension which essentially forms one outer layer of the final web and that a further binder other than the main binder is supplied to the part of the fiber suspension which essentially forms the second outer layer of the final web. Method according to claims 3-6, characterized in that the binder content in the two outer layers of the final web is different and preferably also has a binder content other than the binder content in the rest of the web. Method according to one of the preceding claims, characterized in that the main binder is supplied to all parts of the fiber suspension so that in the layers where another binder is present, the main binder is present in addition thereto. ' Method according to one of the preceding claims, characterized in that the main binder is organic, for example a phenolic resin base, and that at least one of the parts of the fiber suspension which essentially forms the outer layer of the final web is supplied with an inorganic binder, for example a clay suspension. f! Male reference figures Figure 1: 1 melting plant 2 gutter 3 spinning wheels 4 jet 5 shaft 6 casing 7 air flow 8 fibers 9 collecting belt 10 (directional arrow) 11 roller 12 roller 13 suction box 14 mat 15 (directional arrow) Figures 2 and 3: 16 mat, thin 17 belt conveyor 18 belt conveyor 19 belt conveyor 20 receiving conveyor 21 bays 22 (direction arrow) Figure 4: 24 smelter 25 gutter 26 spinning wheels (26 ') 27 spinning wheels (27') 28 air flow (28 ') 29 receiving belts 30 center spreader 464 796' Figure 4, cont .: 31 center spreader 32 center spreader 33 center spreader 34 binder 35 nozzle 36 line 37 binder stream 38 channel 39 opening 40 wall 41 nozzle 42 line, binder 43 line, compressed air Figure 6: "44 binder 45 sill 46 chamber 47 belt 48 suction box 49 roller 50 (direction arrow) 51 output (chamber) 52 chamber end 53 chamber roll 54 upper part (of 46) 55 chamber roof 56 mineral wool layer 57 nozzle 58 pipe