CA2336982A1

CA2336982A1 - Fibre mat

Info

Publication number: CA2336982A1
Application number: CA002336982A
Authority: CA
Inventors: Jean Casimir Le Bell; Ulf Erik Westerlund
Original assignee: Individual
Current assignee: Roctex Oy AB
Priority date: 1997-07-11
Filing date: 1998-07-10
Publication date: 1999-01-21
Also published as: WO1999002766A1; FI972955A0; FI972955A; AU8341798A

Abstract

The invention relates to a fiber matting primarily intended for the surface coating of e.g. plywood boards in order to level out their unevennesses and to make the surface strong and tight. The fiber matting is characterized in tha t it includes a mineral fiber-based fiber structure with good evenness and a bimodal fiber length distribution. The invention also comprises a method of manufacturing this fiber matting in one or several stages, with dispersing a nd recollecting so that at least the last stage takes place without the use of the gravity force. The invention further comprises a method of using the fib er matting for the coating of material surfaces.

Description

WO 99!02766 PCT/FI98100584 Fibre mat In the manufacturing of plywood, frequent defects occur in the layer that should fcrrm the surface of the plywood board. The same problems are common in other wood pro-ducts like chipboards. These surface defects will cause problems associated with use. If the boards are used in concrete forms the :Final concrete surface will be uneven and may require machining. Problems in connection with lo~ the front rake may also occur. If the plywood board or the chipboard is to be used in connection with other pro-ducts, their appearance will be made uglier and the app!-ication of any decorative final surfaces will be more difficult.
Until now, these problems have, in principle, been solved according to the following four different methods:
- by careful selection of the material used in plywood manufacturing, the surface defects can be minimized;
fit) - by making the surface even by machining, e.g. using grinding, in particular, when no deep surface defects oc-cur;
- by filling the cavities, the surfaces of the plywood boards have been made even;
- by applying a smoothing layer, it has been possible to make the surfaces of plywood boards, chipwood boards, and the like even.
The latter method differs from the others in that it 3!3 changes the characteristics of the surface as a whole, and in that it adapts to, to express it briefly, to all kinds of boards with wood as their material.
The method can be carried out by, before pressing, apply-ing a fiber matting, essentially comprising a mineral ffiber impregnated by a binding material, to one or both sides of the board material. During pressing, the fiber matting will level out all. uneven spots and then, after the binding material has hardened under pressure, form hard and firm board surfaces.
The invention relates to this method and constitutes an improvement of an earlier procedure. In spite of its rather wide use, this procedure has not appeared to be an optimal one.
If the surface upon which a fiber matting is to be applied has a defect in the form of a cavity, one of two extreme phenomena may occur. In the first of these extremes, the fiber matting will act as a liquid. Under pressure, the fiber matting material will flow so that its density, i.e. its material mass per volume unit, remains unchanged the whole time. In reality this extreme case cannot be reached, as the fiber matting, in order to secure its manageability, must remain as a whole. It is not desirable either because the material of the fiber matting could just vanish over the edges if there were no specific obstacles, which in pratice are not obtainable.
In the other extreme, no material transfer takes place in parallel with the surface of the board blank. This results in the fact that the density of the fiber matting in the middle of the cavity will be considerably lower than at the other points of the surface. A weakening will become apparent, after a period of surface wear, in the form of surface unevenness. This is one of the problems which the surface coating should eliminate.
Researches have shown that, in reality, we are quite close to this extreme. The only possibility to compensate for this phenomenon has been to produce oversize fiber mattings so that the weakenings, which emerge in connec-tion with the cavities on the surfaces of the wood material surfaces, do not reach harmful dimensions.

WO 99/02766 P~TlFI98/00584 However, in practice there is a condition making this situation more diff_Lcult. fiber mattings for said purpose are manufactured bared on mineral wool spread upon a band and then impregnated. It is well known that mineral wool ' mattings are normally chara.cterized-by unevenness so that the fiber mass vari<~s between different positions. In thick mattings, i.e. those with a large quantity of fiber mass per surface ar~aa, there is always a levelling factor in the form of random. If t:he fiber mass in one layer of the matting is small within a certain area, there is a strong likelihood that in t:he other layers the masses will be normal, or even bigger than normal, whereby a levelling or compensation has occurred.
1> In thin mattings, having a surface weight actual for instance in lining of plywood boards, such a levelling does not take place, or its extend is relatively limited.
This means that in any fiber matting, there may usually very well be either too much or too little material in the middle of a cavity in the wood. If there is too much, the consequences will have no importance a.t all. However, if there is too little material, this will mean that the density in the fiber matting in the middle of the cavity will be even lower than it would have been if the 2'5 material mass in th.e fiber matting had been normal. ' In practice, it is not possible to achieve an absolutely even fiber matting if the costs have to be taken into consideration. However, it has turned out that this prob-lem can be solved t:o a satisfactory extent even when the uniformity is not perfect, if it satisfies the condition that the uniformity, measured in the way described below or in any other way with equal results, reaches 20 o at the most, calculated as a variation factor.
However, this requ_Lres that in the fiber matting there should be a flowing binding material which will transfer the pressure from the press to the individual fibers.
Also some form of a filler may be needed to modify the lubricating characteristics of the binding material.
Therefore, the objective of this invention is to provide a fiber matting consisting mainly of mineral fibers, pri-marily intended to be used as a face for plywood and the like in order to reliably level out all of the uneven spots in them in connection with the pressing and curing of the binding material, hereafter called the filling capacity, and to otherwise improve its characteristics, so that the mineral fibers form a uniform structure and are uniformly distributed over the fiber matting so that the scattering of the deformation resistance does not exceed 20 0, calculated as the variation factor, and so that the distribution of the fiber lengths is bimodal.
The uniformity of a fiber matting can be defined in sev-eral different ways. for this purpose the surface weights of small surface elements can be determined. Research has, however, proved that the deformation resistance according to the method described below, supported by Fig. lA, is a better representation of of the filling capacity of the fiber matting. According to this method, a metal cylinder A with a diameter of 10 mm, fixed to the measuring rod B in a measuring clock C, can from above press against a fiber matting D laying on a horizontal, even base E. The combined weight of the metal cylinder A
and the measuring rod B is 200 grams.
According to this method, 20 areas of fiber matting with-in the surface area of 210x297 mm (A4) are measured. The mean value M of the distances and the standard deviation s are calculated, and from them the variation factor v is calculated using the formula v = 100 * s/M

WU 99/02766 P~T/FI98100584 A more extensive scattering may lead to the risk of an unreliable filling capacity. Uniformity is importat even on surface covers ccmtaining no or only local uneven spots. Thus, in casE: one, when trying to obtain a 5 strengthened surface:, it is essential that there are no weak areas on it as, in practice, the technical outcome will depend on the characteristics of the weakest points.
It is obvious that a certain material mass is required to make the fiber matta_ng effective, whatever material it is made of. For most practical purposes, the surface weight requirement is at least 150 g/mz, preferably at least 250 g/mz An important precondition for the good functioning of the fiber matting in practice is that its fiber length dis-tribution is bimoda:l. It i~; true that a low average length may result in good filling capacity but it gives insufficient inner coherence to obtain the treatment characteristics req»ired in practice. A high average length gives coherence but lacks in filling characteris-tics. Looking at th~~ problem superficially, it should be possible to find an average length in between, with both sufficient filling ~haractE~ristics and sufficient treat-ment characteristics, this has, however, not proved viable. Suprisingly it has been proven that a suitable fiber matting can be obtained by providing a bimodal fiber length distribution.
It has been impossible to develop a structurally formu-lated theory for this phenomenon, but it is most likely that bimodality results in a mobility of the shorter fibers forming a mass in re=_lation with the long ones, with a tendency to form a more immobile grid.
By way of definition, such a bimodal fiber length distribution is characterized by two frequency peaks.

Both of these frequency peaks need not be equally high.
If they are not equally high the lower one must, however, be sufficiently high so that the probability a random de-viation of a unimodal distribution is in practice eli-urinated.
Bimodality may form the basis for seeing the fiber mass as containing two fiber fractions, one shorter and the other longer.
It has been noted that an increased uniformity down to the variation factors less than l0 per cent and up to 5 per cent will result in observable advantages but also that the excessive uniformity obviously does not mean increased filling capacity, nor any other advantages.
In order to make the longer fibers function optimally and give strength without greatly reducing the inner mobility that contributes to the filling capacity, the relation between those fiber lengths that refer to the two frequency maxima in the bimodal fiber length distribution must be greater than 5, preferably also greater than 10.
In this way, good results have been achieved by the mix-ing of average 25 mm length fibers in a fiber mass, the average fiber length of which is about 3 mm. When the longer fibers were reduced to an average length of 10 mm a large quantity of the longer fibers had to be added to achieve sufficient strength and the filling capacity became too low. As the long fibers normally cost more than the short ones, in this case, even the economy of the production will suffer.
Fig. 1B shows an example of a bimodal fiber length dis-tribution with two frequency maxima, one by 3 mm and the other by 22 mm. The relation between these two fiber lengths is 7 and thus the shown example should satisfy the requirement according to Claim 3. Also Fig. 1C, show-ing a bimodal fiber length distribution with the fiber length maxima by 3 and 15.5 mm respectively, satisfies the requirement according t.o Claim 3.
However, and not surprisingly, it has appeared that other characteristics of i~he fiber matting are also influencing its filling capacit~~. One ~~uch characteristic is the orientation of the :~ibers. Depending on the way the fibers are grouped :in bundles or clusters, their filling ~.0~ capacity is reduced. The same is true if a larger number of fibers is orient;~ted perpendicular or nearly perpen-dicular against the fiber matting level. Further, it is not convenient to 1~'t a large number of fibers take a certain direction, ~.g. the' running direction of the fiber matting. Instead, the fibers in the fiber matting should be mainly randomly orientated on the level of the fiber matting.
It is very difficult to directly observe that the fibers are randomly orientated. Instead, it is preferred to measure the tensile strength of the fiber matting in longitudinal and transversal directions. The relation between these values must not be less than 0.5 and not greater than 2. Preferably, the relation should be between 0.7 and 1.5. Outside these limits the fiber orientation is no longer random enough and the filling capacity may become too minimal.
Treatment of the fiber matting in different phases empha-3~0 sizes the tensile =,trength requirements of the longitu-dinal direction move than those of the transversal direc-tion. Therefore, it: is an advantage if, in any given interval, the value. of the former is higher than that of the latter.
In particular, the thicker fiber mattings according to this invention sometimes have the tendency to delaminate under treatment, i.e. to form layers caused by insuffi-cient inner coherence in their thickness direction. This is due to the fact that an overwhelming part of the fibers, and especially the long ones if any of those are involved, are placed at the level of- the matting and only a few of them have a significant reach in the perpendicu-lar direction against this level. This relationship can be corrected by so-called needling, providing sections of the longer fibers reach through the fiber structure in its thickness direction. This is an efficient means to keep the structure together.
The bimodal fiber length distribution can be achieved by mixing several fiber materials with distinctly different length characteristics. If these fiber materials are also made of different basic materials, e.g. so that one is inorganic and the other organic, it will be easy to determine, even after mixing, their respective proportions, e.g. in volume percentages.
If the bimodal fiber length distribution has been the outcome of something else, or if the two fiber materials to be mixed consist of the same basic material, this can appear more difficult. If the fiber length distributions are so widely separated that there is between them an empty fiber length interval, even in this case the pro-portions between them can be determined. If, on the con-trary, the fiber length distributions are overlapping, there are cases when it will not be possible to determine whether a certain fiber belongs to one portion or to the other. Therefore, to be able to give the mutual propor-tions, a convention is used where the fiber length between the two frequency maxima, showing the lowest fiber frequency, is used as divisor. If this lowest fre-quency covers several fiber lengths, or one fiber length interval, the average value of these fiber lengths or of the fiber length area is used instead.

W() 99/02766 PCTIFI98/00584 In the example shown in Fig. 1B, the following fiber lengths between the two frequency maxima are empty: 11, 13, 14, 15, 16, and 18 mm. The average value of these is 14.5 mm, thus giving, by way of definition, the boundary between the two f ibf=_r materials .
The example shown i:n Fig. 1.C shows the minima by 9 and 11 mm, respectively, a:nd thus the boundary between the two distributions is, by way of definition, 10 mm.
The researches concerning the present invention show that the proportion of the longEar ffibers, i.a. of those belonging to the longer of the two fiber length distribu-tions, must be up to at least 8 per cent, preferably at least 15 per cent of the total fiber volume.
Even the length characteristics of the fiber component with long fibers is significant, although the most important is that their average length is considerably more than that of the rest of the fibers. The longer of the two fiber distributions must have its average length within 10 to 80 mm, preferably 20 to 40 mm. Any shorter fibers have a lower strength contribution and any longer fibers do not seem to be beneficial in relation to the material mass they represent.
In the experiments, three categories of long fibers have been shown to be e:~pecially advantageous, regarding dif-ferent aspects such as functioning, costs, and willing-ness to be uniformly distributed. In this context, func-tioning means considering the positive effect that the long fibers have on the tensile strength of the fiber matting, and the negative effect they have on its filling capacity, probably due to the fact that they limit the mobility of the relatively shorter fibers. One of these categories comprises organic fibers, e.g. the synthetic fibers of polyester, polypropylene, polyamid or of polyester/polypropylene, polyester/polyethene, polypropylene/polyethene and polyester/copolyester. This category may also comprise the viscose fibers. Their maximum thickness in this case must be 7 decitex. The 5 second category comprises fibers of -glass, conventional glass fibers or fibers of glass with a basalt like compo-sition. Their maximum thickness must be 3 decitex. Both of these categories are characterized by a smooth fiber surface and a high tensile strength. These result in a 10 good strengthening effect, without a too high reduction of the mobility of the shorter fibers during the pressing process.
Even natural fibers such as cotton, jute, linen, and sisal fiber, or modified natural materials such as cellu-lose fiber, have been shown to be effective. Although their surface is not smooth, they are functional, prob-ably due to the fact that they are, instead, broken by the powers which influence them during the pressing pro-cess.
Not unexpectedly, even the fiber thickness of the compo-nent with long fibers is significant. The optimal value for this parameter has appeared to be within a fairly narrow area, i.e.
- for organic polymer fibers 3 to 7 decitex, preferably 5 to 6 decitex - for conventional glass fibers o.7 to 3 decitex, prefer-ably 1 to 2 decitex - for fibers with a basalt like composition 0.2 to 3 decitex, preferably 1.2 to 2.2 decitex.
The desirable inner mobility of the fiber matting depends, very significantly, on the fiber morphology of the mineral fiber component. The shorter fibers seem to play a key role here, and their ratio should be limited, i.e. the relation between their length and diameter. This WO 99!02766 P~CTIFI98100584 can be expressed so that the fibers with a length under 5 mm have a relation between their average lengths and their average diameters between 100 and 1000. A lower ratio leads to a structure with a too insufficient inner strength, notwithstanding the positive influence of the long fibers. A too high ratio works against the inner mobility and leads too lowered filling capacity.
The information about the fiber diameters mentioned here-by concern the optical microscope measurements magnified by 500 times. They are given as averages of 200 individ-ual diameter measurements by using good preparation and observation methods.
The fiber length in:Eormation indicates direct measure-ments from a projection picture with the ability to mag-nify the fiber sample 100 times.
In order to comply 'with it~~ final function, the fiber matting has to cooperate with a binding material. This invention also comprises a fiber matting with such a binding material. The task of a binding material is obvi-ously to bind, together wii~h the pressing procedure, the compressed fiber matting into a tight and strong layer.
At the time of pressing, the binding material can also have the role of a lubricating medium, transferring and distributing the pressing power to the individual fibers in the fiber matting. To this end, the most suitable binding material should flow, at least at high tempera-tures such as in a thermo-compressing process.
However, the binding material in its cured state has its most significant impact on the surface against which the fiber matting has ~>een pressed under heat. In order to achieve the right combination of tightness, wear resis-tance, and overall resistance against chemical and microbe attacks, preferably unsaturated polyester, but WO 99/027b6 PCT/FI98/00584 also vinyl ester, epoxy; phenolformaldehyde, melamine or the like can be used.
The binding material can include fillers, the task of which in this case can be manifold,-as they can partly modify the effect of the binding material to help the inner movements in the fiber matting during the pressing process, and partly modify the mobility of the filler particles in the fiber structure to improve its filling capacity. Furthermore, the filler particles can improve the wear resistance of the ready-made outer surface, other resistances, or some other new or improved charac-teristics. Suitable filler materials are fine- grained mineral powders such as limestone flour, talcum powder and wollastonite flour.
Among the additional characteristics that can be added by suitable choices of filler, the following can be mentioned: fine corn pyrite carbide gives the coating of plywood or chipwood boards high friction characteristics, grains of materials with a high portion of relatively lightly splitting chrystal water can give added fire resistance, graphite flour can improve the release char-acteristics against e.g. concrete.
Even inorganic filler materials can be used. For instance, wood powder can regulate the flow characteris-tics of a flowing binding material and reduce its required quantity.
The filler material must have a fine-grained structure, or more precisely, its average grain diameter must be under 10 ~,m, preferably under 5 Vim.
The filler material element in the completed mix of the binding material and the filler must be within the range of 15 to 50 weight per cent, preferably 20 to 30 weight WO 99/02766 P~T/FI98100584 per cent, out of the total weight of the binding material, including the filler.
In order to obtain 1=he highest possible effect from the filler material°s ability to increase the final outer surface, the concenl~ration of the filler particles must be higher on the side of the fiber matting which is turned outwards during pressing. On the other hand, in order to obtain the best possible filling capacity the concentration of th~~ filler particles may need to be higher on the side ~~f the fiber matting which is turned inwards during pressing. These two effects can be combined by making 'the concentration of the filler par-ticles higher on both sides of the fiber matting than in its middle. The concentration of the filler particles needs not be the same on both sides, and not even the same filler material is necessary. As a matter of fact, both the method and the concentration can be individually adapted to the use or to the advantage of strengthening 24) the complete product coated by the fiber matting on one side, and to the need or to the advantage of increasing the inner mobility and the filling capacity.
The part of the binding material without filler must be 2!~ 50 to 200 weight per cent, calculated with the weight of the fiber material, in order to achieve the right filling and the desired final characteristics.
To make the penetration of the binding material into the 30 fiber matting easier, especially if it is relatively thick and/or of high density, the fiber matting can with advantage be equipyed with holes or weakenings, e.g. by driving needles through it. The art of these, as well as their density, or mutual distances, is in this case 35 adapted according t:o the need of the penetration help required by the actual case.

Normally, a needling with a needle density of 10 to 20 seedlings per cm2 may be suitable, provided that the diam-eter of the needle is about 0.3 to 1 mmz. The use of thicker needles brings about deeper penetrations. When striving to obtain improved and even, but not very deep, penetrations, thinner needles and smaller distances should be chosen.
This invention also includes a method of manufacturing a fiber matting, primarily intended for plywood board coat-ings and the like, in order to level out, in connection with pressing under heating, their unevennesses and to improve their characteristics, whereby the fibers in the fiber matting form a coherent structure and are evenly distributed over the fiber matting, so that the scatter-ing of the deformation resistance does not exceed 20 per cent, calculated as a variation factor, and whereby the ffiber length distribution is bimodal.
According to the present invention, the mineral fibers are dispersed into the air, together with a fiber compo-nent of long fibers, and then the fiber dispersion is laid on a mobile, perforated receiving means, without using gravitation, as a matting, and using air suction.
In a suitable way, the starting point is preferably a thin web of mineral fibers that are dispersed using two or more brush rollers, possibly after a fiber shortening run by crushing them between the rollers.
The receiving part can be made of a band or drums.
In order to achieve sufficient evenness, the dispersing and the recollection may require more than one stage. In that case, the fiber component with long fibers will most conveniently be added before the first dispersing.

WO 99!02766 PCT/FI98/00584 It is convenient to add a binding material to the fiber matting in a separai~e process, by adding at least one thin and tight carrier layer, e.g. polyethene foil, whereby the binding material is inserted between the foil 5 or the foils and th~~ fiber matting before they are put together. After thi;~, when the foil or foils and the fiber matting are pwt together, at least a partial inserting of the binding material in the fiber matting will take place.
At this stage of the process, it is possible to prepare one or two mixings of bind_Lng material and filler that will be laid over one or two foils to be thereafter rote-grated into the fiber web from the first process part, so that the side of the foil or foils coated by the binding material and the filler are turned against the fiber web, whereafter the integrated :Layers, the fiber web and the foil or foils will be pres:~ed together.
The process itself can be carried out in several ways, according to the prevailing conditions. It is possible either to coat the surfaces of the carrier layer that are against the fiber matting or the carrier layer with the binding material, or apply the binding material to the completed fiber mataing before coating the carrier layer or the carrier layers, or to use a combination of these methods so that the binding material is laid directly on the upper surface of the fiber matting and a protective layer is laid on the lower surface which is then combined 3.0 with the fiber mati:ing.
If the fiber matting is mainly transferred horizontally and the binding mai~erial with its possible filler is dry, it can be strewn on the lower foil and/or on the upper X35 surface of the fiber matting before the foil or foils are combined with the :fiber matting.

In order to ease and control the penetration of the mix of the binding material and filler in a later phase of the process, a treatment with needles can in some cases provide advantages when thinnings or holes are made in the fiber matting. If there are long fibers, these can be made to better bind the fiber structure together by using needles with barbs that make some of the long fibers stretch through the fiber structure in its thickness direction.
The needling density is most conveniently within the range of 10 to 20 needle impacts per cm=. The preferable cross profile of the needles is the farm of an equilat-eral triangle with rounded edges, and thickness 0.5 mm, measured as the height of the equilateral triangle. If it is not just local thinnings but also the orientetation of some fibers in the transversal direction that is re-quired, the needles should be equipped with barbs, pre-ferably projecting out from the needle point.
The needles are preferably placed on one or several needle booms with a density of 1000 to 3000, preferably about 2000 needles per meter, and in about 20 rows, off-set in relation to each other by a half of the needle distances in the rows.
In those cases where it seems to be useful, it is also possible to ease the penetration of the binding material/filling mix into the fiber structure by treat-ment after the combination and pressing together, There are several treatments to be used. Preferably, it can be carried out by passing the fiber matting through two or more rollers, with a relatively light pressure on the fiber matting. Preferably, the rollers can be equipped with thicker sections or spots causing a periodically varying treatment in the form of changing compressions and lowerings of pressure.

The present invention also comprises a use of the fiber matting whereby the fibers form a coherent structure and are evenly distributed over the fiber matting so that the scattering of the d~=_formation resistance does not exceed 20 per cent, calculated as the variation factor, and so that the fiber length distribution is bimodal. The use according to the invention comprises, in the first phase, the one-sided or dowble-sided impregnation of the fiber matting and, in connection with this, a ore-sided or a double-sided coating is applied to it, together with a protective foil. After the protective layer has been removed, a material layer, e.g. a plywood board or a lay-er of wooden particles or :Fragments, is applied to one or both sides, and then the material layer and the fiber matting or fiber mattings are transferred to a press where the layers are pressed together by high pressure, and the binding material is fixed to it, preferably by heat under the pressing operation.
Thus, the operation, comprises three part processes, the manufacturing of true fiber matting itself, its impregnation, and t:he pressing together of the impregnated fiber matting with a material layer in combi-nation with which 3_t will be used. These three processes can be carried out in one operation, without using any rolling, storing or transportation of the fiber matting between the phases. The manufacturing and the impregnation of the fiber matting can take place in one single phase, and then the impregnated fiber matting is ?~0 transported, rolled in a ~;uitable way, to its final site of use as e.g. a coating c>f plywood.
Another alternativf=_ is that the fiber matting is manufac-turgid at one site and then transported to another site X35 where the impregnavion with the binding material and the coating of a material layer takes place, closely connected with eac'.n other,. In this case it may even be possible to eliminate the use of a protective foil.
Finally, the manufacturing of the fiber matting, its impregnation, and its final combination with e.g. a ply-wood board can take place at three different sites, using transportation and possibly even storage between each phase.
In the following, the invention is described in more detail with references to Figs. 2 and 3. Fig. 2 shows the manufacturing of a fiber matting, and Fig. 3 a double-sided impregnation of such a fiber matting.
Fig. 2 shows the insertion of a relatively thin mineral wool matting 1. This can be manufactured in a conventional way, by melting minerals, e.g. basalt, with a lesser addition of dolomite or limestone in the furna-ce, e.g. a cupola furnace, to a continuous melt flow from the furnace, leading this flow against the periphery sur-face of the spinning wheel that is the first one in the series of wheels arranged in a cascade. From there, the melt is slung out in the form of e.g, fibers that are then transferred by air streams to a perforated collec-tion band through which the air is sucked away, leaving the mineral fibers as a matting laying on the conveyor band. The surface weight of the mineral wool matting 1 is 50 to 250g/mz and it is carried by the conveyor band 2 in the direction shown by the arrow 3 in between the two brush rollers 4 and 5.
The brush roller 4 rotates anticlockwise and the brush roller 5 clockwise, although with a lower peripheric speed than the brush roller 4. The peripheric speed of the brush roller 5 is higher than the speed of the band 2 and the peripheric speed of the brush roller 4 is at least three times higher. The density and diameters of the brush rollers can to a certain extent be adapted to WO 99/02766 P~TJFI9$/OQ584 the characteristics and surface weight of the mineral wool matting 1 used as input material.
By the work of the brush rollers 4 and 5, the mineral wool matting 1 is broken to fine small fragments 6 that are slung into a first fiber chamber 7 and deposited in the form of a new fiber matting 8 on its bottom, consist-ing of a conveyor band 9. The band 9 transports the newly formed fiber matting 8 out from the fiber chamber 7 under a tightening roller 10. After hawing come out from the fiber chamber the fiber matting 8 passes between two rollers 11 and 12 z~pplying~ such a high adjustable pres- ', sure against each other that the fibers in the fiber mat-ting are made considerably shorter by breaking them under pressure. The rollers are driven and pressed against each other by conventional arrangements not shown in the fig-ure. After passing between the rollers, the fiber matting 8 is laid down on i~he conveyor 13. While it is transferred on thi:~, a long fiber component 14 is added 2;0 to it from above and dosed with a device symbolized in the figure by the monveyor 15.
The dispersing and recollection processes taking place by using the elements indicai~ed here by 2 to 13 can be doubled or tripled. Regarding any dispersing and recol-lection process, by suitably adjusting the mutual distances of the brush rollers and their rotation speed, as well as their tightness and diameters, e.g. the even-ness of the output fiber matting can be made better than that of the input matting.
The surface weight of the rebuilt fiber mattings is important as well. This is regulated by increasing or reducing the speed of the band or the bands 9. The con-85 venient adjustment of the device is such that the surface weight before the last dispersing, to be described below, remains between 7C to 120g/m'.

The more or less rolled and once or twice dispersed and recollected fiber matting 8 is now directed, with a long fiber component 14, in between a further pair of brush rollers 16 and 17, corresponding to the brush rollers 4 5 and 5, in a fiber chamber 18, corresponding to the fiber chamber 7. The brush rollers 16 and 17 now disintegrate the material of the fiber matting 8 and the long fiber component, covering it with a dispersion in the fiber chamber 18. Forced by gravity and an airstream directed l0 downwards, the reason of which will be described later, the particles in the dispersion now move mainly downwards. The possible larger parts and the non-fiber material is cast as far away as possible by the force of the brush rollers and, in principle, they follow the path 15 indicated by the curve 19. On the other hand, the fiber dispersion is sucked by the blower 20, in principle fol-lowing the path of the curve 21, against the perforated band 22 so that a new fiber matting 23 can be formed.
Thereby the air sucked by the blower 21 is separated from 20 the flow and passed through the band 22 via the channel 24 to the blower. After the blower, the air passes a fil-ter 25 and is then led via the channel 26 back to the fiber chamber 18. This is how the airstream downwards and past the brush rollers 15 and 17 is created.
The newly formed fiber matting 23 is now directed by the band 22 over to the conveyor 27 that will remove the fiber matting from the fiber chamber 18 and then feed it under the tightening roller 28.
After this, the fiber matting 23 can be taken for needl-ing in a conventional needling device, here symbolized by the conveyor 29 and the needling tool 30, with its needle plate 31, and a device 32 for its movements up and down.
The possible larger parts and the non-fiber material fall down onto the band 33 and are taken out from the fiber chamber 18 under the tightening roller 34 as waste 35.
By adjusting the rotation :peed of the blower 20, or by a damper in the channel 26, the air flow circulating through the fiber chamber .L8 can be adjusted so that a suitable separation grade us achieved. With a small flow, mainly just the totally free fibers are caught on the band 22 and a major part of the fiber material falls down onto the band 33. On the contrary, if the flow is bigger ld) the balance between the influence of the virtually upwards directed airstream in the vicinity of the band 22 and gravity is offset so that a larger part of the fiber material is sucked up towards the band 22.
1:~ The waste 35 may contain considerable quantities of fibers. Especially because of small air flows and the high purity of the material collected on the band 22 caused by this, a ~~ignificant quantity of the fibers, that would as such still be usable, may be directed to 20 the waste side. They can then be recovered to the process with or without a reparation process set between. One of the ways to recover- them is to disperse the waste in an airstream and then direct it to a cyclon where an adjust-able part of the solid materials is separated, while the 25 rest of them, containing most of the fibers, are recol-lected to a matting that in turn may be taken back to the process together with the input fiber material 1.
Due to the fact that gravity does not contribute to the 30 depositing of the :~iber material on the band 22, the influence of the a:irstream will be the only force to bring the material there. As the airstream through a cer-taro part of the active band surface is reduced the more fiber material is deposited onto it, the airstream 3.5 becomes relatively bigger through those parts of the active band surface where the fiber material quantity is not so large. Therefore, z-elatively, the depositing will increase there. In this way a levelling of the surface weight takes place so that, in the end, it will be suffi-cient.
Thus, the evenness is largely a function of the efficiency of the dispersing and of the formation of the depositing process. The important aspect of the latter is that the gravity force does not contribute to it. This does not mean that the active band surface of the band 22, i.e. that part of the band through which the airstream is flowing, should be horizontal when the air flow, in principle, is vertical in an upwards direction.
The active band surface can also be vertical when the airstream, in principle, is horizontal. All forms between 25 these can also be considered, e.g. an active band surface that forms a 45° angle against the horizontal level and an airstream that is in principle streaming through it in a direction diagonally upwards.
In more detail, the evenness also depends on certain pro-cess parameters, like the rotation speed of the brush rollers, the surface weights of the various parts in the process etc. It is not possible to give a general deter-mination of these, as they have to be adapted to the respective fiber materials input in the process. Several variations can be considered. For any professionals, it should anyway be possible to find out, with a limited input, in which way the process parameters and the number of dispersings should be chosen in order to achieve the desired results.
The fiber matting 23 manufactured in this way can be rolled to the rolls for intermediate storage and trans-portation to an impregnation plant to be impregnated with a binding material or to be transported directly to the plant if the plants are located near each other and it is otherwise desirable to do so.

It can also be taken away t:o other operations or uses, ', for instance to become a ca~pillar-breaking layer in building constructions exposed to humidity.
Fig. 3 shows the principal layout of a plant for impreg-nating a fiber matting manufactured by the method described here, or lay some other method within the range of the invention. Tl~e binding material is pumped out from three binding material tanks 36 by dosing pumps 37 and 38 1t) into a guiding system 39 and 40. The binding material pumped out may contain jusi~ one binding material or a mixture selected freely wii~hin a certain range. The num-ber of the binding material tanks, three in the figure, can be chosen according to needs. The guiding system 39 leads the binding material or the binding material mix into a mixer 41. A filler or a mix of various fillers is added to this. From the beginning, the fillers are stored in filler silos 42. The filler is taken from these by the dosing input devices 43 and 44 to the horizontal conveyors 45 and 46. These can be of a screw type. The conveyor 35 supplies the filler or the filler mix to the mixer 41 via the feeder pipe 47.
In a similar way tr:e pipe system 40 conducts the binding material or binding material mixture from the metering pumps 38 to the mi~:er 48, to which also the horizontal transport 46, which is fed from the dosing feeders 44, leaves a filler or a filler mixture via the feeder pipe 49.
The binding material and the filler are mixed in the mixers 41 and 48 to form am even mix. This mix is then pumped from the mi:~er 41 by a peristaltic pump 50 via a pipe 51 to a sweepE~r 52. This spreads an adjustable quan-tity of the binding material/filler mix to form a thin and even layer on a carrier layer 53 coming out from a storage roll 54.

In a similar way, the mixing of the binding material from the pipe system 40 and the filler from the feeder pipe 49 takes place to make it to an even mix. This mix is then pumped from the mixer 48 by a peristaltic pump 55 via a pipe 56 to a sweeper 57. This spreads out an adjustable quantity of the binding material/filler mix to form a thin and even layer on a carrier layer 58 coming out from a storage roll 59.
The carrier layer 58 coated this way is now transferred by the transferring rollers 60 over to a conveyor 61.
A fiber matting 63 manufactured using the method described, or by any other method, is rolled out from the storage roll 62. It can also come direct, without any intermediate rollings or rollings out. The fiber matting is laid dawn by the transferring rollers 64 onto the car-rier layer 58 on the conveyor 62. Thus, the carrier layer 53 is laid down on the fiber matting 63 by using the transferring rollers 65. The combination 66 with three layers is now directed under the band press 67, compris-ing an upper band 68 and a lower band 69. The band press 68 presses the three layers together so that the mix of the binding material and the filler is pressed into the fiber matting.
After the pressing together, the fiber matting 70 equipped with the binding material, the filler, and the carrier layer, is now lifted from the conveyor 61 using conveyor rollers 71. At the treatment station, comprising a series of lower rollers 72 and a series of upper rollers 73, the fiber matting can be treated 67 in a con-trolled way whereby the penetration of the binding material in the fiber matting increases. Finally, the fiber matting 70 is rolled up into a roll 74 and is now ready to be used according to its purpose.

The described impregnation can also be applied on one side only.
The invention can ~~lso be operated by using dry, 5 powderlike binding materials, possibly mixed with a fil-ler in a way that is, in principle, compatible with what is shown in Fig. 3. The means of preparing and transfer-ring the binding m~cterial and the mix of the binding material and the f~_ller, respectively, are in that case 1o composed accordingly. They may, advantageously, be closed pneumatic systems. Fig. 4 shows one such arrangement. The arrangement of the main parts complies with the one shown in Fig. 3, the dif~~erence being that the upper side of the fiber matting :is covered by a binding material in 15 powder form using a delivery device 75 that, with a cell feeder connected t~~ a vibrator, not shown in the figures, delivers the bind ing material in powder form, with or without the filler mixed in, over the width of the fiber matting 63 and to :be depo~~ited on it. It is then covered 20 by the carrier layer 53, t:he task of which, in this case, is mainly to act as a protective or covering layer. When this layer has been laid, the pressing together takes place in the band press 6',7.
25 Fig. 5 shows an arrangement where the binding material in powder form is applied to both sides of the fiber matting 63. This is done by feeding both the fiber matting 63 and the carrier layers 53 and 58 from above and with a cer-tain distance between them. The carrier layer is then moved against the fiber matting using the press rollers 76. Immediately before the carrier layer and the fiber matting are pressed together by the rollers, the binding material in powder form is added to the mixture from the feeders 75. After this, the combination of the carrier :35 layer, the fiber matting, and the binding material can continue downward~> towards the conveyors 61 and into the band press 67.

WO 99/02766 PCTIfI98/00584 Designations used in figures and text:
A metal cylinder B measuring rod C measuring clock D fiber matting E base 1 mineral wool matting 2 band 3 direction arrow 4 brush roller 5 brush roller 6 fragment of fiber matting 7 fiber chamber 8 fiber matting 9 band 10 tightening roller 11 roller 12 roller 13 conveyor 14 long fiber component 15 conveyor 16 brush roller 17 brush roller 18 dispersion of fibers 19 curve for non-fiber material 20 blower 21 curve for fibers 22 perforated band 23 fiber matting 24 channel 25 filter 26 channel 27 conveyor 28 tightening roller 29 conveyor 30 needling tool WO 99/02766 P~'T/FI98/00584 31 needle plate 32 arrangement for needle plate movement 33 band 34 tightening ra~.ler 35 waste 36 binding material tanks 37 dosing pumps 38 dosing pumps 39 pipe system 40 pipe system 41 mixer 42 filler silos 43 dosing feeder 44 dosing feeder 45 conveyor 46 conveyor 47 feeder pipe 48 mixer 49- feeder pipe 50 peristaltic pump 52 pipe 52 sweeper 53 carrier layer 54 storage roll 2.5 55 peristaltic pump 56 pipe 57 sweeper 58 carrier layer 59 storage roll ,30 60 conveyor rollers 61 conveyor 62 storage roll &3 fiber matting 64 conveyor rollers 35 65 conveyor rollers 66 combination of carrier layer and fiber matting 67 band press 68 upper band 69 lower band 70 fiber matting with carrier layer 71 conveyor rollers 72 lower rollers 73 upper rollers 74 roll of fiber matting 75 delivery device for binding material in powder format, with/without filler 76 pressing rollers

Claims

1. A fiber matting mainly comprising mineral fibers, pri-marily intended to be used as surface coating of plywood boards and the like, in order to level out, in connection with its pressing during the fixing of a binding material to it, the unevennesses in them and otherwise to improve their characteristics, characterized in that the fibers form a coherent structure and are evenly distributed over the fiber matting so that the scattering of the deforma-tion resistance does not exceed 20 per cent, calculated as a variation factor, and that the fiber length distribution is bimodal.

2. A fiber matting according to Claim 1, characterized in that the scattering of the deformation resistance does not exceed 10 per cent, calculated as a variation factor, preferably not less, than 5 per cent.

3. A fiber matting according to any of the above Claims, characterized in that the higher frequency maximum of the bimodal fiber length distribution is within a length that is at least 5 times bigger than the length of the lower frequency maximum, preferably at least 10 times.

4. A fiber matting according to any of the above Claims, characterized in that the mineral fibers are mainly orientated at the level of the fiber matting so that the relation between their tensile strength in longitudinal direction and their transversal direction is 0.5 to 2.0, mainly 0.7 to 1.5, preferably 1.0 to 1.5.

5. A fiber matting according to any of the above Claims, characterized in treat a part of the long fibers has sec-tions reaching through the fiber structure in its thick-ness direction.

6. A fiber matting according to any of the above Claims, characterized in that the long fiber part comprises at least 8 per cent of the total fiber volume, preferably at least 15 per cent.

7. A fiber matting according to any of the above Claims, characterized in that the average fiber length of the long fiber part is 10 to 80 mm, preferably 20 to 40 mm.

8. A fiber matting according to any of the above Claims, characterized in that the long fiber part comprises - either organic polymer fibers, their maximum thickness preferably corresponding 7 decitex - or conventional glass fibers, their maximum thickness preferably corresponding 3 decitex - or fibers with basaltlike composition, their maximum thickness preferably corresponding 3 decitex - or natural fibers, as cotton, jute, linen, and sisal fibers - or modified natural materials as cellulose fibers - or a mix of these fiber types.

9. A fiber matting according to any of the above Claims, characterized in that the fibers the length of which is under 5 mm have a relation between their average lengths and average diameters of 100 to 1000.

10. A fiber matting according to any of the above Claims, characterized in that it also includes a binding material that is flowng, at least for a higher temperature.

11. A fiber matting according to any of the above Claims, characterized in that it includes a polymerized or polymerizing binding material like unsaturated polyester, vinyl ester, epoxy, phenolformaldehyd, melamine or the like, preferably unsaturated polyester.

12. A fiber matting according to Claim 10 or 11, charac-terized in that in the binding material there is a fil-ler, preferably a fine-grained, mineral filler, e.g.
limestone powder.

13. A fiber matting according to Claim 12, characterized in that the filler comprises 15 to 50 weight per cent, preferably 20 to 30 weight per cent, of the total weight of the binding material, including the filler.

14. A fiber matting according to Claims 12 and 13, characterized in that there is more filler material near one or both of the surfaces of the fiber matting than in its middle part.

15. A fiber matting according to Claims 12 to 14, characterized in treat there is more filler material near one of the surfaces of the fiber matting than of the other.

16. A fiber matting according to Claims 10 to 15, characterized in that the binding material without filler comprises 50 to 200 weight. per cent, calculated on the weight of the fiber material.

17. A fiber matting according to any of the Claims above, characterized in that in the coherent fiber structure there are thinnings or holes that ease the penetration of the binding component.

18. A method of manufacturing a fiber matting essentially consisting of mineral fibers, primarily intended to be used as surface coating for plywood boards and the like, in order to level out, in connection with its pressing during the fixing of a binding material to it, the unevennesses in them, and otherwise to improve their characteristics, characterized in that the mineral fibers are dispersed into the air together with a fiber compo-nent of long fibers and the fiber dispersion is then laid upon a moving, perforated receiving device, without using the gravity force, as a matting by sucking away the air in it.

19. A method of manufacturing a fiber matting according to Claim 18, characterized in that the fibers are dispersed more than once and recollected in the form of a matting between the dispersing phases.

20. A method of manufacturing a fiber matting according to Claims 18 and 19, characterized in that the fiber com-ponent with long fibers is added before the final dispersing.

21. A method of manufacturing a fiber matting according to Claims 18 to 20, characterized in that the mineral fibers are exposed, before their dispersing or their final dispersing, to a fiber cutting process by mechan-ical treatment, preferably by being directed between two or several rollers pressed against each other by a sig-nificant power.

22. A method of manufacturing a fiber matting according to Claims 18 to 21, characterized in that one or two tight carrier layers are laid on the fiber matting, e.g.
made of polyethene foil, and thereby a binding material is added to it, possibly with a filler, between the fiber matting and the carrier layer or the carrier layers a) either by coating the surfaces of the carrier layer that are against the fiber matting with the binding material b) or by adding the binding material to the completed fiber matting before coating the carrier layer or carrier layers c) or by a combination of these methods so that the bind-ing material is added to the upper surface of the fiber matting by method a) and the lower surface by method b) and then by pressing these two or three layers together.

23. A method of manufacturing a fiber matting according to Claims 18 to 22, characterized in that the fiber mat-ting, before being pressed together with the carrier lay-er or with the carrier layers, preferably in connection with its recollection after dispersing or the final dis-persing, is treated by needles that can be equipped with barbs.

24. A method of manufacturing a fiber matting according to Claims 22 and 23, characterized in that the fiber mat-ting, after its combination with the carrier layer or with the carrier layers, the addition of the binding material, and the pressing together of the layers, is treated by rollers, either smooth or modified by patterns of rounded ribs, or by some other way in order to create inner movements in the fiber material.

25. A method to use the fiber matting according to Claims 1 to 9, characterized in that it is first impregnated on one or both sides, thereby at the same time possibly coa-ting its one or both sides with a protective foil, and a material layer, as plywood board or a layer of wooden particles or fragments, is applied to one or both sides after removal of this protective foil, whereafter the material layer and the fiber matting or the fiber mattings are taken to a press to be pressed together under high pressure, and where the binding material is fixed to it, preferably by heat during the pressing oper-ation.