DE19740676A1 - Fiber adhesive coating method - Google Patents

Abstract

To coat fibers with an adhesive, the adhesive is applied while the fibers have a residual moisture content of <= 100%. After the application of the adhesive, the fiber clumps are broken down. In an Independent claim, an assembly has a tower (4) which can be filled (18) and emptied (20). The adhesive is applied to the fibers in the tower through feeds (8) in the tower or its wall (6). A mechanism (22) to break down fiber clumps is at the outlet of the tower. Before application, the residual moisture content in the fibers is set by drying at <= 100% and pref. 10-1%. The fiber clumps are agitated in an air stream, giving turbulence which breaks them down in the air eddies. Or the glued fibers can be separated in a refiner or mill. The separated fibers are passed to a workstation to be formed into fiber materials. The fibers, in clumps or separated, can be fed to an intermediate store. The adhesive is applied to the fibers in a fiber/air stream moving at a speed of <= 150 m/s and pref. <= 50 m/s and especially <= 10 m/s, moving on a straight or a spiral path. The environment is controlled, in the application zone, to a given temperature and/or air humidity. The residual moisture content of the fibers can be varied while the fibers are being glued and/or separated. The adhesive glue is fed according to batches of fed fibers or fiber masses, or the vol. of delivered adhesive is set on a time scale. The adhesive is delivered by jets. The tower has a jet system (14) for the delivery of air or other gases into it, or through its walls, and also jets to generate air turbulence to eddy and/or advance the fibers. The tower is vertical, horizontal or at an angle, and is at least partially conical. The fiber clumps are broken down by a rotor, sieve, beating plate or the like, followed by winnowing where surplus air is diverted from the fiber/air stream for at least partial return to the tower after its temp. and/or humidity levels have been set. A control registers the fiber feed to set the volume of adhesive to be delivered by fiber batches or on a timed basis. The control system also sets the conditions of the environment within the tower according to the fiber moisture content and its mass, to give a temperature and/or humidity profile between the tower entry and exit. The consistency of the adhesive is adjusted according to the wetness and/or temperature of the fibers to be coated.

Description

The invention relates to a method for gluing fibers, in which the glue on Fibers with a fiber moisture below 100% is applied, a device for Implementation of the method and a method for controlling the gluing of fibers.

In the following, fibers are used to refer to all lignocellulosic fibers which be used in particular for the production of wood-based materials. Typical fibers are those made from wood chips or from annual plants, from palm trees or grasses after RMP- (Refiner Mechanical Pulping), TMP- (Thermomechanical Pulping) or CTMP processes (Chemo-Thermomechanical Pulping) are generated, but also by Chemical wood pulping fibers are included here. The glued fibers can preferably be used for the production of wood-based materials; they are in front especially suitable for the production of fiberboard. A typical one, but far from that the only example is the use of glued lignocellulosic fibers for the production of MDF boards (medium density fiberboard).

Fibers that are used to manufacture wood-based materials are made from liquid-soaked wood chips. Before gluing, the fibers must be on a fiber moisture (water mass based on absolutely dry fiber mass) below 100%, preferably between 1 and 10% to be dried for permanent gluing to ensure and to prevent so-called steam bursts, these are cracks and Disruptions in the fibrous structure of the wood-based material caused by steam bubbles generated during gluing. As "dry fibers" in contrast to the liquid-soaked fibers that are present after the shredding of wood chips hereinafter referred to as fibers with a fiber moisture content below 100%. Particularly preferred however, it is fibers with a fiber moisture between 1 and 10%.

To produce wood-based materials from fibers, the fiber mass is between 5 and 30% Glue added based on the absolutely dry fiber mass. As glues various synthetic resins are used, often for example phenol-formaldehyde, melamine  Formaldehyde or, if waterproof gluing is not required, urea formaldehyde. All natural glues and synthetic resins are subsequently used as glue called, which are applied to lignocellulosic fibers to wood materials to manufacture.

In the production of medium density fiberboard (MDF), a so-called "blow- Line "glueing. Fibers are directly in the Refiner at high temperatures and high pressure in the so-called "blow line" with the Glue mixed. The gluing takes place by injecting the glue into the blow line. The Blow-Line is located between the refiner and a fiber dryer. Because of the Differential pressure between refiner and fiber dryer shoot the still moist and very hot fibers at a speed of 200 to over 450 m / s through the blow line. The turbulence in the blow line causes the mixing of the injected glue with the fibers and thereby the gluing of the fibers instead. This The process takes place in fractions of a second. The glued fibers arrive at End of the blow line in the fiber dryer. There they are brought to the desired humidity dried and then pressed into sheet materials or molded parts.

This type of gluing is used in every MDF plant today. It is technical easy to do, but has two major disadvantages. For one, at the drying of the fibers formaldehyde released from the glue on the fiber surface. This is released into the atmosphere with the dryer exhaust air. Therefore, they are expensive Installations such as exhaust air washers, electrostatic filters and the like for cleaning the dryer exhaust air from MDF fiber dryers is required or is required by the respective Approval authorities required. Exhaust air cleaning systems are in the purchase and very expensive to operate.

On the other hand, the glue partially hardens or diffuses during the drying process into the fibers and is then no longer available for connecting fibers Available. As a rule, a fiber moisture (fiber moisture means water mass based on absolutely dry fiber mass) of over 100% to a fiber moisture of 10% dried down. The hardening glue no longer contributes to fiber binding. He  is lost, so to speak. It is assumed that about 20% of the glue used after the Drying are no longer reactive. Since glue is more expensive than fibers, this represents a loss an important cost factor.

As an alternative to the wet gluing described above, the Large scale dry gluing of MDF fibers with glue mixers from the Particle board industry tried. Chip mixers were used for dry gluing of fibers used for gluing wood chips in chipboard production Find. The construction of such mixers comprises a rotatable, usually arranged horizontally Cylinder penetrated by a central shaft. The shaft is with exit openings provided for the glue. If necessary, funding for the chips in the cylinder or on attached to the shaft.

Dry gluing is mainly due to the poor glue distribution and the formation of fiber agglomerates failed. These cause a non-uniform surface of the Fiberboard and a heterogeneous structure in the bulk density of the board. The through the Fiber agglomerates caused fluctuations in bulk density can damage the Guide press plates of modern continuous press lines. The energy consumption of such mixing units is considerable.

It is the object of the invention to propose a method for gluing fibers which minimizes the use of glue. It is a further object of the invention to provide a To provide apparatus for performing this method with the fibers as little glue and energy as possible are optimally glued. After all it is Object of the invention to propose a method for controlling the glue application with which the gluing takes place under optimized conditions.

The object described above is achieved in that glue on fibers with a Fiber moisture of less than 100% is applied and that fiber agglomerates, which are characterized by form the application of glue, after the gluing can be dissolved again. So far all measures that were tried were aimed at fibers with a fiber moisture content glueing below 100%, to make the gluing so that no fiber agglomerates  arise. The method according to the invention also strives for this, and also separates however between the steps of gluing the fibers and dissolving Fiber agglomerates.

Contrary to the prejudices of the experts, it has been found that the uniform Gluing of the relatively dry fibers is guaranteed, and that the Fiber agglomerates without damaging the fibers, i.e. without loss of fiber strength can be dissolved again. It is with the procedure according to the main claim especially possible, dry fibers, i.e. fibers with a fiber moisture below 100%, preferably to glue between 10 and 1% fiber moisture. The particular advantage of this Measures is that the dry, glued fibers after dissolving about Existing fiber agglomerates are fed directly to the production of wood-based materials can be. Glue losses caused by the hardening of glue when drying fibers are avoided here.

The way in which the fibers are glued and subsequently dissolved Fiber agglomerates can be fed in as desired. It is a mechanical one Transport of the fibers, for example by screw conveyors, is conceivable. Especially however, it is preferred that the fibers be in an air stream, hereinafter as a fiber / air stream designated, promoted. This type of transport is particularly inexpensive and easy to implement. Elaborate funding is eliminated and the fiber / air flow is easy to control. Air is especially in the context of this description Ambient air meant, but this term also includes all other gases that can be used to transport the fibers and, if necessary, also to treat the fibers are.

A preferred embodiment of the method provides that the fibers before gluing be dried. The moisture content of the fibers is preferably below 20% or less than 10%, depending on the requirements of the production, which is based on gluing then dried, even below 5% to below 1% moisture content. When drying possibly already taken into account that by applying glue again moisture is applied to the fiber.  

The fiber agglomerates are preferably dissolved in that the fibers and the Fiber agglomerates, which are conveyed in a fiber / air flow, into a turbulent Flow. Practice the eddies created in turbulent flow Shear forces on the fibers and fiber agglomerates, which are dimensioned so that the Fiber agglomerates are broken down into individual fibers again, but the fiber itself remains undamaged. Because the glue adheres more firmly to the fiber surface than the fibers to each other, the individual fibers still have a uniform glue on.

But it is also easily conceivable to use fiber agglomerates by mechanical means Disassemble devices again. By dissolving fiber agglomerates after the Gluing is achieved in that the particularly homogeneous and desired by the processors uniformly glued fiber is provided, which is a prerequisite for a particular is uniform and trouble-free production of fiberboard.

Suitable for generating turbulent flow in which fiber agglomerates are dissolved especially plant parts that come from chip and fiber production or processing itself are already known. Refiners, defibrators or mills are made according to the invention operated that contrary to the original purpose, the fibers and Fiber agglomerates not mechanically processed when passing through the refinder or the mill be ground, for example to a higher degree of grinding, but only in turbulent flow swirled and isolated, so "fluffed".

For example, a refiner runs with one when dissolving fiber agglomerates Plate spacing of over 0.2 mm, preferably over 1.0 mm. With this opening width there is no grinding, but the fiber / air flow is between the two plates of the Refiners almost completely set in turbulent flow. Refiners and mills are on known as devices with extremely high energy consumption and therefore exist in itself, for reasons of cost, concerns about the re-use of such system parts yes can also be used to manufacture the fibers themselves. Let go of these concerns refute themselves by the fact that the refiners or mills do not do any grinding work here should exercise. The devices are idle, so to speak. The energy consumption at  Dissolving the fiber agglomerates is very small, so that by using them Devices hardly incur additional costs.

It is easily conceivable to use fibers with high fiber moisture on the above glueing described and if necessary to separate again, then to dry and process. However, it is particularly preferred to have already dried Glue fibers and immediately after dissolving fiber agglomerates Feed molding station for the production of wood-based materials. This very sequence of Process steps ensure an economical use of energy and glue, so that significant compared to the conventional sequence of procedural steps Cost savings can be achieved.

The fibers can immediately after gluing and dissolving the fiber agglomerates to be processed further. However, intermediate storage can also be arranged around the Collect fibers before gluing or after dissolving the fiber agglomerates before they are fed to gluing or production.

As already mentioned, fibers in the blow line are at speeds of over 200 glued to over 450 m / s and then dried. It is obvious, that both because of the unpredictability of the drying process and because of the only approximate adjustable conditions of the gluing itself, an excess of glue must always be provided, which incurs significant costs. It is therefore considered a particular advantage of the The inventive method considered that it is possible to use fibers at low Glueing speeds because the glue additive is dosed precisely and economically can. The speed of the fibers during gluing is in any case below 150 m / s, preferably below 50 m / s. Falling speeds in the range are particularly preferred between 0, 1 and 10 m / s. At such low falling speeds, which by appropriate control of the fiber / air flow are adjustable, there is sufficient time To glue fibers optimally.

It is judged to be particularly advantageous if the fibers are present in a fiber / air stream natural gravitational rate of fall decrease. But it can also  be appropriate to expose the fibers to a certain countercurrent, for example a spiral path through the glue zone to increase the dwell time in the Increase glue zone or to add fibers after gluing for further processing condition.

Another advantageous embodiment of the method according to the invention also depends with the low speed of the fibers when gluing. During the Glueing can, according to the invention, the climate, in particular temperature and air humidity the environment of the fibers can be adjusted as it is for applying the glue and for example to prevent curing of the glue is most advantageous. Also this measure therefore contributes to the economical use of glue. Temperature and Humidity as a critical parameter for the ambient climate can be identified, for example Simply adjust the addition of tempered air with the specified air humidity.

If necessary, gluing can be carried out in the presence of inert or protective gases. for example, when the presence of oxygen is not suitable for the glue.

Due to the lower speed of the fibers when gluing, it is possible to Moisture content of the fibers during gluing and / or dissolving the Targeting fiber agglomerates within certain limits. For example possible to slightly dampen over-dried fibers or fibers that are applied of a glue that is too watery has too high a moisture content, by drying optimally set again for further processing.

The inventive method can be in the device described below perform particularly easily and inexpensively. The device for gluing Fibers with a fiber moisture content of less than 100% comprise in the simplest embodiment a tower, which has a filling opening and a discharge and, means for Application of glue and a device for dissolving fiber aggregates, the Discharge of the tower is arranged. The means for applying glue are in the tower or arranged in the wall of the tower.  

The tower is of any cross-section, but preferably cylindrical. The The filling opening and the discharge are each at opposite ends of the tower attached, preferably in the area of the end faces. The filler opening can be as simple Opening for introducing the fibers into the tower, but it can also be designed as closable opening or be designed as a lock, for example when through Opening or closing the filling opening the fiber mass to be introduced into the tower should be controlled or if defined climatic conditions in the tower must be observed. Of the Discharge can be done in the same way as the filling opening as an opening, for example a pipe connects, be designed as a closable opening or as a lock. The Device for dissolving fiber agglomerates either directly adjoins the Discharge to or through a connecting line, for example a pipe, with which Discharge connected.

The fibers enter the tower through the filling opening. The tower stands on the longitudinal axis of the tower, preferably vertical, but it can also be inclined or even be arranged horizontally. The fibers are mechanical or - which is preferred - in a fiber / air flow entered the tower and conveyed through the tower. When the tower is vertical, it is particularly advantageous that the fibers, gravity following, without additional energy input through a gluing zone, in which the gluing is carried out in the tower can sink through. The tower has turned out to be special proven suitable to carry out the gluing, because it is a sufficiently large Has volume to enable a throughput, for example, one Can supply fiberboard production. In addition, a tower is easy to erect and can easily all means for gluing, for supplying air or Whirl up the fibers if necessary to carry out the procedure required are.

The device for dissolving fiber agglomerates, the above already closer has been described, is arranged on the discharge of the tower. After gluing, the Fibers, especially if a refiner or a mill is arranged on the discharge of the tower by the suction generated by the rotor in the refiner or in the mill, dressed. Special subsidies between the tower and refiner or mill are therefore not  required.

The means for gluing, which are attached in or on the tower, are preferred as nozzles formed, which are connected to a reservoir via feed lines. Nozzles are ideal for atomizing the glue finely and thus on the surface of the numerous fibers that are conveyed through the tower. The nozzles can in the simplest, cheapest and therefore most advantageous embodiment in the Wall of the tower can be arranged. The tower and the nozzles for the glue are like that to coordinate with each other that the nozzles do not apply the glue to the opposite Spray wall of the tower, but on the other hand also the complete gluing of the fibers is guaranteed. The arrangement of the nozzles can be chosen freely, it can circular, spiral or in any other suitable manner. The area of the tower in which the nozzles for gluing the fibers are attached is called Glue zone designated. The glue can be injected pneumatically in the air stream take place or airless by spraying by means of static pressure.

In addition to the means for gluing, according to a preferred development, the Device means for introducing air or other gases into the tower or in the Wall of the tower arranged. The means of introducing air or other gases are in the simplest case, the mouths of corresponding supply lines. These are preferred However, means for introducing air or other gases are also designed as nozzles. The nozzles are either distributed in the glue zone or outside the glue zone arranged. They can be used for various purposes. By means of introduction For example, the course of the fiber / air flow and / or the speed of air can be used the fibers are guided and influenced. The air can be cooled, warmed, humidified or be dried, so that the climate in the tower, can be adjusted especially in and after the glue zone. As above air is usually introduced into the tower. However, should be for special An inert gas or protective gas atmosphere may be required for this purpose can be realized at any time using the means for introducing gases. It is also possible, gaseous reaction components that should interact with the glue to bring this into the tower. But also additives that are needed for the finished product  Wood-based products that are important, such as fungicides, can already be used here be introduced.

Finally, means for swirling and / or in the tower or on the wall of the tower Conveying fibers can be arranged. These agents can be used as baffles, rotors, Baffles or the like may be formed. Because the conveyor speed and the Swirling the fibers for the quality and uniformity of the gluing the key is to arrange such swirling means one measure the result of gluing improved significantly.

The above-described means for gluing, for introducing air and for Swirling and / or conveying fibers are preferably on or in the wall of the Tower attached. This is structurally simpler and also from the point of view of Maintenance cheaper than inserting such funds inside the tower. If however, there are reasons for placing these funds in the tower, for example Space reasons, this is easily possible.

It is particularly preferred that the above-described agents for gluing, for Introducing air and adjustable for swirling and / or conveying fibers are trained. If nozzles are used, they should be adjustable in order to to be able to optimally align the spray cones after installation, so that blind spots are avoided. It may also be necessary to make changes to the Adjust when the throughput of fibers in the tower changes or when other glues are processed. Also the spray cone of the nozzles and the throughput should be variable for the reasons mentioned.

The tower for carrying out the method according to the invention is preferably vertical arranged, with a filling opening at the top and a discharge at the lower end of the Tower. With this arrangement, gravity is used to convey the fibers in the Fiber / air flow used and thus the energy expenditure minimized. Depending on the arrangement and Alignment of existing production facilities may require the tower sloping or lying, i.e. to be arranged horizontally. If the tower is not vertical, then there is  to ensure that the fiber / air flow runs approximately in the middle of the tower. Deposits on the walls should be avoided as far as possible To prevent "overgrowth" of the tower. By appropriate arrangement of nozzles however, this can be achieved in a simple manner.

In the simplest embodiment, the tower is cylindrical or approximately cylindrical. It but it is preferred that the tower is conical at least in sections. Especially in the area of the discharge after the glue zone, the tower should be conical be designed to increase the cross-sectional area Speed of the fiber / air flow to cause the formation of turbulence is supported. However, it is also possible to make the tower conical overall assemble two truncated cones into a tower so that the maximum cross section of the Tower is between the filling opening and discharge. With the shape of the tower, the Turbulence and the conveying speed of the fibers can be influenced effectively.

The means for dissolving fiber agglomerates are preferably as refiners or mills educated. Common to these known plant parts is that they at least have a rotor, i.e. a fast rotating component. Due to the geometry of the refiner or the mill is guaranteed that a fiber / air flow that is on a fixed Conveying route from the filling opening through the glue zone to the discharge and through the Refiner or the mill is moved, is set into turbulence in a defined manner, without mechanical damage to the fibers. Dissolving the Fiber agglomerates are also done very gently because when the Turbulence additional air is torn into the fiber / air flow.

In order to use the fiber / air flow in complete turbulence with the least possible use of energy to move, it proves to be advantageous to strainers, baffles or baffles in the area the means for dissolving fiber agglomerates. With these measures the already low use of energy to dissolve fiber agglomerates be reduced and also a complete dissolution of fiber agglomerates be guaranteed.  

According to an advantageous embodiment, the performance of the means for resolving Fiber agglomerates adjustable. As already described above, it is only a small one Drive power required to keep the fiber / air flow as complete as possible in turbulence to offset, but it may be that an adjustment of the Performance of the refiner or grinder is necessary.

A particularly preferred development of the invention provides that the fiber / air flow after dissolving the fiber agglomerates is passed into or through a classifier in which Excess air is separated from the fiber / airflow when generating the Turbulence was recorded. By inserting a sifter, the volume of the Fiber / air flow reduced again to a significantly lower level. The excess air is preferably through lines between the classifier and the means for Introducing air and other gases are arranged, circulated. It's on that it is possible to simply discharge excess air into the environment, but it is advantageous - among other things because of the cheaper energy balance - the cycle at least partially close. Especially when it is not air but other gases in the tower, it is recommended to close the circuit to cleaning systems savings that would otherwise have to be installed when discharging residual air into the environment.

According to a particularly preferred development of the device for gluing Fibers are in or on the lines that run between the classifier and the means for Introducing air into the tower means that allow temperature and / or The humidity of the excess air can be adjusted before it is returned to the Tower is fed. If necessary, cleaning devices can also be used that remove undesirable substances from the air flow to be circulated. The aforementioned means for adjusting temperature and / or air humidity, i.e. cooling or heaters or humidifiers or dehumidifiers prove particularly then advantageous if the climate in the glue zone or in the tower as a whole according to certain Is controlled.

As an independent inventive part that helps to solve the problem, fibers to glue economically and to avoid excess material and / or energy consumption  A method for controlling the application of glue to the fibers is described below. depending on the fiber mass to be glued and / or the fiber mass proportion of glue to be applied means for applying glue individually, in groups or be adjusted overall so that they each have a predetermined proportion of glue Unit of time or per unit of weight based on the fiber mass to be glued into the tower bring in. In contrast to the prior art, it is according to what is proposed here Process possible to influence the glue application on the fibers and the Control reaction conditions accordingly in detail. This allows the glue and Energy consumption can be optimized and the uniformity of the glue application to the fibers be specifically improved.

An improved glue application is also achieved in that the means for introducing of air or other gases in the tower so that one at a time predetermined turbulence and / or a predetermined path of the fiber / air flow is observed. With this measure, the path of the fiber / air flow through the Tower so matched to the glue zone that the glue introduced is as complete as possible is deposited on the surface of the fibers.

In addition, the fiber mass entered in the tower per unit of time and / or the Fiber moisture detected, and depending on these values, the temperature and / or If the air humidity is set in the tower or in the glueing zone, the fibers can - what the state of the art is not possible - optimal for the requirements of production, in particular on the requirements of the presses for pressing the fibers, for example to be set to MDF boards on the glue.

The temperature when entering the tower or around the fibers as essential reaction parameters for the behavior of the fibers during gluing and that According to an advantageous development of the method, the glue is also hardened recorded and included in the control.

It can be seen as progress when temperature and humidity, addition of air or other gases, transport speed and others described above  Overall parameters in the tower can be set. According to one particularly preferred further development of the invention is, however, one for certain Areas or zones of the tower each with optimized flow and / or climate profiles set. For example, in the area of the filling opening (the filling zone) Introducing tempered air for the fiber / air flow optimally maintains the temperature of the fibers the gluing can be set. Humidity and temperature, but also the path and speed of the fiber / air flow are specified so that the Glue application runs without losses and with minimal formation of fiber agglomerates. in the The area of the discharge can be adjusted by adjusting the temperature and humidity Fiber moisture of the glued fibers are adjusted so that the pressing of the fibers runs smoothly. To set these profiles, the respective means for Introducing glue or air or other gases or the means for swirling or Conveying fibers can be controlled individually or in groups.

To optimize the gluing, it is further proposed that the consistency of the Adjust the fibers to be glued depending on the air humidity in the tower. Since the moisture content of the fibers is a critical factor with regard to pressing, and because by applying the glue additional moisture is applied to the fibers a precise adjustment of the consistency of the glue means an improved Adjustment of the glued fibers to the pressing.

Exemplary embodiments of the invention are explained in more detail below using the example of FIGS. 1 to 3. Show it:

Figure 1 is a schematic representation of a device for gluing fibers in longitudinal section.

Fig. 2 is a cross section through the ad Beleimzone a device according to Fig. 1;

Fig. 2e shows a longitudinal section through the Beleimzone a device according to Fig. 1; such as

Fig. 3 ac is a schematic representation of different tower shapes in longitudinal section.

Fig. 1 shows an apparatus 2 for gluing of lignocellulose-containing fibers. A tower 4 is the core of the device 2 . The tower 4 is made of stainless steel and - if necessary - coated with Teflon on the inside. The coating prevents the glued fibers from adhering to the wall 6 of the tower. The tower 4 is about 10 m high and has a diameter of about 1.5 m; it is essentially cylindrical. Glue application nozzles 8 , the spray cones of which are adjustable, are let into the wall 6 of the tower 4 . The glue application nozzles 8 are connected to a glue reservoir 12 via a feed line 10 . Furthermore, 4 air nozzles 14 are let into the wall 6 of the tower. The air nozzles 14 also have adjustable spray cones. The air sprayed in through the air nozzles 14 is supplied via feed lines 16 .

At the upper end of the tower 4 , a simple fill opening 18 is attached, which is neither closable nor changeable in its passage. Other embodiments of the filling opening, for example openings with an adjustable diameter or locks or the like can be used if necessary. Fibers with a fiber moisture content below 100% are introduced into the tower 4 through the filling opening 18 . The fibers are preferably fed either from a storage container or from a dryer.

A discharge 20 is arranged on the opposite end face of the tower 4 . The discharge 20 connects the tower 4 to a refiner 22 . The walls 24 of the discharge 22 are conical towards the cleaner 20 . The discharge 20 opens approximately in the center of the refining disks 26 . The conical discharge 20 brings about a significant increase in the flow velocity due to the narrowing of the cross section and thereby promotes the formation of turbulence.

The refiner 22 has two profiled disks 26 , one of which is stationary (stator) and one disk is rotating at approximately 4,000 revolutions per minute (rotor). The disks are spaced approximately 1.5 mm apart. At this disc distance, the rotor runs roughly at idle; it does not do any grinding work because the passage between the stator and rotor is too large. The refiner 22 creates turbulence that leads to the dissolution of fiber agglomerates. The refiner 22 is also made of stainless steel and optionally coated, for example with Teflon, so that the glued fibers do not stick to the disks 26 or other parts of the refiner 22 .

A sifter 28 is connected downstream of the refiner 22 and is connected to the reimer 22 by a line 30 . In the sifter 28 fibers and excess air are separated. The excess air is led out of the classifier via line 16 and air nozzles 14 back into tower 4 . From the sifter 28 , the glued fibers are either fed to a storage container or a molding station or a press for producing wood-based materials.

The device 2 shown in FIG. 1 is particularly suitable for carrying out the method according to the invention for gluing lignocellulose-containing fibers with a fiber moisture content below 100%. The fibers are produced conventionally, for example by RMP, TMP or CTMP processes from wood chips. The chips are defibrated at high humidity, over 100%, usually over 200% water content based on the absolutely dry fiber mass. The fibers are then dried and then fed to the glue, either directly from the dryer or from a storage container.

The fibers are conveyed into the tower 4 in a fiber / air flow through the filling opening 18 . Moving the fibers in an air stream - or other suitable gas stream - is simple, energy efficient and inexpensive. The air flow directed from the filling opening 18 to the discharge 20 is preferably generated by the rotating refiner 22 , which continuously sucks in the fiber / air flow. As an alternative or in addition to the refiner 22 , the fiber / air flow can also be generated by the air nozzles 14 . The speed of the fiber / air flow is much lower than in the blow-line method described above. The fiber / air flow has a speed of less than 150 m / s, preferably less than 50 m / s. It is particularly preferred that the fiber / air flow moves through the tower 4 and the gluing zone "B" at a speed which corresponds approximately to the natural falling speed. In the fiber / air stream, the fibers are moved to the glue zone "B", shown hatched in FIG. 1. The glue zone "B" is the area of the tower 4 in which glue application nozzles 8 are embedded in the wall 6 of the tower. The fibers are sprayed in the glue zone "B" with approx. 10 to 20% glue based on the absolutely dry fiber mass. The glue is sprayed in finely divided and is almost completely deposited on the surface of the fibers.

In order to minimize glue losses, the air nozzles 14 , which are arranged between the glue application nozzles 8 in the glueing zone "B", are oriented such that they align the fiber / air flow so that the fibers are exposed to the spray cone of the glue application nozzles 8 as evenly as possible. The spray cone of the air nozzles 14 can also be oriented counter to the main direction of movement of the fiber / air flow.

Gluing the fibers with the device described here already minimizes the Formation of unwanted fiber agglomerates. Previously known methods for dry gluing of fiber put chip mixers with relatively small volume and mechanical Conveyors that are well suited for gluing chips, but the cannot be used at all for gluing fibers. Fibers have completely different features Dimensions, much higher surface area per unit of weight and accordingly smaller Bulk density, but no significant stiffness.

The fiber agglomerates, which still form despite the improved glue application, are dissolved again in a subsequent process step. For this purpose, the fiber / air stream with the fiber agglomerates contained therein is fed to the discharge 20 and from there to the refiner 22 . The discharge 20 is conical and the cross section tapering towards the cleaner 22 causes a steady increase in the speed of the fiber / air flow and thus an increase in the turbulence in the fiber / air flow. When passing the refiner 22 , the rotor of which rotates at about 4,000 revolutions per minute, the fiber / air flow is completely set in turbulence. In the turbulence, the fiber agglomerates dissolve without the fibers being damaged. The disc spacing of the discs 26 of the refiner 22 is dimensioned at approximately 1.5 mm so that the glued fibers are not ground. The speed of the rotor and the distance between the disks are to be understood as approximate information. The particular settings are chosen by the person skilled in the art so that the desired success, the dissolution of the fiber agglomerates, is achieved with the least possible use of energy.

The glued, now isolated fibers are fed in the fiber / air stream from the refiner 22 to the sifter 28 . Excess air that was sucked in when the turbulence was generated is separated again. The classifier, like the system parts already described (tower 4 , Reimer 22 ), is made of stainless steel and optionally coated. The same applies to the lines through which the fiber / air flow is led.

The classifier 28 is a component known per se for separating excess gas or air quantities. The excess air is at least partially returned to the tower 4 through lines 16 . The fibers are either conveyed by the sifter 28 into a storage container or transported to a forming station, which forms, for example, plate blanks, which are pressed into fiber plates or molded parts in a subsequent press.

Further measures for optimizing and improving the implementation of the method can be taken with a device according to FIG. 1. The air nozzles 18 can not only be used, for example, to control the fiber / air flow or to swirl the fibers, they can - all, in groups or individually - also be used for spraying in gases which influence the reactivity of fibers or glue, if appropriate the sprayed-in gas can also be a component of the glue.

Means for swirling the fibers are not shown in the tower 4 in FIG. 1. However, it should be pointed out that such means, for example baffles, baffles or the like, can be fitted in the tower 4 or on the walls 6 of the tower 4 in order to ensure optimal guidance of the fiber / air flow.

The glue application is advantageously controlled in such a way that the sprayed-in amount of glue is dosed in each case depending on the fiber mass entered in the tower 4 . For this purpose, the throughput of the glue application nozzles 8 is increased or decreased, depending on the mass of the fibers to be glued per unit of time.

It may be desirable to change the moisture content of the fibers before, during or after gluing in order to adjust the fibers and possibly also the glue as well as possible to the subsequent pressing. The method according to the invention offers the possibility of specifying the climate in the tower 4 , in particular temperature and / or air humidity, so as to specifically influence the fiber moisture. For example, over-dried fibers can be re-moistened from the filling opening 18 up to the entry into the glue zone "B" by spraying in moist air, or insufficiently dried fibers can be further dried by spraying in dry air. The premature curing of glue or the penetration of glue into the fibers can be prevented by setting a defined temperature and air humidity in the glue zone. Temperatures of approx. 20 to 80 ° C, but usually approx. 20 to 40 ° C at a humidity of approx. 40 to 95% are particularly suitable for glue application. The air humidity itself can also be below 40%, but measures must then be taken to prevent the fibers from becoming electrostatically charged. Statically charged fibers tend to settle on the tower wall, they are no longer easily carried in the fiber / air flow. Under these conditions, all technically used glues including PMDI isocyanate glues can be used for fiber gluing.

After gluing, for example, the excess liquid taken up during the glue application can be at least partially removed again by drying by spraying dry air through the air nozzles 14 which are arranged between the gluing zone "B" and the discharge 20 .

Such a climate profile can be set according to the invention easily by arranging air nozzles 14 and glue application nozzles 8 and by detecting fiber mass entered in the tower 4 and possibly the fiber moisture as well as by controlling the nozzles 8 and 14 as a function of fiber mass and moisture. It is also advantageous to additionally record the temperature of the fibers when entering them in the tower 4 and to set the temperature and, if appropriate, the air humidity in the tower 4 as a function of the temperature of the fibers and the fiber moisture. It is particularly preferred if the climate in the tower 4 is set before, in and after the gluing zone "B" in each case depending on the state of the unglued or glued fibers.

In order to dry or humidify the air to be sprayed into the tower as required and to heat or cool the air, it is expedient to arrange appropriate driers or humidifiers, heaters or cooling devices in line 16 , which connects the classifier 28 to the air nozzles 14 . The devices arranged in the line 16 and the air nozzles 14 can either be set separately from one another or a programmable control unit can be inserted which is provided or connected with measuring points or sensors which measure the temperature of the fibers and, if appropriate, their moisture and / or detect the temperature and / or humidity in the tower 4 . The glue application is controlled automatically.

FIGS. 2a-e show a cross-section through the tower 4 is arranged in the wall 6 of the tower 4 glue application nozzles 8 and the air nozzles 14. The nozzles 8 , 14 can either be arranged in separate planes, as shown in FIG. 2a, or they may be in one plane, as shown in FIG. 2b. The nozzles 8 , 14 can spray radially into the tower 4 (see FIGS . 2a, b) or the spray cone can be directed into the tower 4 at an angle a or at an angle b, as shown in FIGS. 2c-e. The angles a to b can assume values between 0 and 90 ° in relation to the longitudinal axis "A" of the tower 4 .

FIGS. 3a-c show in addition to the illustrated in Fig. 1 form further variants of a tower 4, can be glued in the fibers having a fiber moisture of less than 100%. Fig. 3a shows a located to the discharge 20 conically tapering from the filling opening 18 tower 4. The discharge 20 and tower 4 merge here, since this conical shape of the tower 4 enables an ideal transition to a device for dissolving fiber agglomerates. The swirling of the fibers is effectively supported by the continuous tapering of the tower 4 from the filling opening to the discharge. FIG. 3b shows a tower 4, which widens from the feed opening 18 to the discharge 20 conical. It is advantageous here that the fiber / air flow takes a particularly long way through the gluing zone "B", so that the gluing can be controlled well. Fig. 3c shows a tower 4, which is preferably expanded in an upper portion of the filler opening 18 to the end of Beleimzone "B" conical and tapers conically from the end of Beleimzone "B" to the discharge twentieth Such a construction is expensive, but combines the advantages of the tower shapes described in FIGS . 3a and 3b. The dimensions of the tower 4 can vary widely, in each case depending on the shape of the tower, on the fiber throughput per unit of time and on the requirements with regard to the climate profile to be set. Construction heights of approx. 5 to 25 m and diameters of 0.75 to 3.5 m can easily prove useful.

Claims (32)

1. Method for gluing fibers, in which glue on fibers with a Fiber moisture is applied below 100% and in the subsequent Fiber agglomerates that are present after gluing are dissolved again. 2. The method according to claim 1, characterized in that the fibers before Gluing to a fiber moisture below 100%, preferably to a fiber moisture be dried between 10 and 1%. 3. The method according to claim 1 or 2, characterized in that the Fiber agglomerates are turbulent in a fiber / air stream so that the Fiber agglomerates can be dissolved again by swirling. 4. The method according to at least one of claims 1 to 3, characterized in that that the fiber agglomerates after gluing to dissolve the fiber agglomerates to pass a refiner or a mill. 5. The method according to any one of the preceding claims, characterized in that the fibers after dissolving the fiber agglomerates of a forming station for Manufacture of wood-based products are supplied. 6. The method according to claim 5, characterized in that the fibers before or after the dissolving of the fiber agglomerates are fed to an intermediate storage. 7. The method according to any one of the preceding claims, characterized in that the glue is applied to fibers that are in a fiber / airflow with a Speed below 150 m / s, preferably below 50 m / s, in particular below 10 move m / s.   8. The method according to claim 7, characterized in that the glue on fibers is applied that move vertically or on a spiral path. 9. The method according to any one of the preceding claims, characterized in that a given climate in the vicinity of the fibers during gluing is set. 10. The method according to claim 9, characterized in that temperature and / or Air humidity in the vicinity of the fibers are set during gluing. 11. The method according to any one of the preceding claims, characterized in that the moisture content of the fibers during gluing and / or dissolving the Fiber agglomerates is changed. 12. Device for carrying out the method according to claim 1 with a tower, which has a filling opening and a discharge, with means for applying Glue, which are arranged in the tower or in the wall of the tower and with a Device for dissolving fiber agglomerates at the discharge of the tower is arranged. 13. The apparatus according to claim 12, characterized in that the means for Applying glue are formed as nozzles. 14. The apparatus according to claim 12, characterized in that means for introducing of air or other gases in the tower in the tower or in the wall of the tower are arranged. 15. The apparatus according to claim 14, characterized in that the means for Introducing air or other gases into the tower are designed as nozzles, which are arranged in the tower or in the wall of the tower. 16. The apparatus according to claim 12, characterized in that in the tower or on  means of swirling and / or conveying fibers on the walls of the tower are arranged. 17. The device according to one of claims 12 to 16, characterized in that the Means for applying glue, means for introducing air or other Gases and / or the means for intermingling and / or conveying fibers, in particular nozzles are adjustable. 18. The apparatus according to claim 12, characterized in that the tower is vertical, is arranged obliquely or transversely. 19. The apparatus according to claim 12, characterized in that the tower at least is partially conical. 20. The apparatus according to claim 12, characterized in that the means for Dissolving fiber agglomerates have a rotor. 21. The apparatus according to claim 12, characterized in that the means for Dissolve fiber agglomerates, sieves, baffle plates or the like. 22. The apparatus according to claim 12, 20 or 21, characterized in that the Performance of the means for dissolving fiber agglomerates is adjustable. 23. The device according to claim 12, characterized in that following the Means for dissolving fiber agglomerates a sifter is arranged, which the Fibers pass in a fiber / air stream and in which excess air comes out Fiber / air flow is separated. 24. The device according to claim 23, characterized in that lines between the sifter and the means for introducing air into the tower are arranged, through which the air separated from the fiber / air flow is at least partially is returned to the tower.   25. The device according to claim 24, characterized in that in or on the Lines between the classifier and the means for introducing air into the tower are attached, means for adjusting the temperature and / or means are arranged to adjust the air humidity. 26. Procedure for controlling the glue application on fibers with a fiber moisture under 100% in a device according to one or more of claims 12 to 25, depending on the fiber mass to be glued and / or each Proportion of glue to be applied by means of fiber mass, the means for applying glue individually, in groups or in total so that they each one Put the specified amount of glue into the tower per unit of time. 27. A method for controlling the application of glue to fibers according to claim 26, characterized characterized in that means for introducing air into the tower and / or means for swirling fibers are set so that a predetermined one Swirling of the fibers and / or a predetermined path of the fiber / air flow is observed. 28. A method for controlling the application of glue to fibers according to claim 26 or 27, in the fiber mass entered into the tower per unit of time and the fiber moisture to be recorded and depending on the fiber moisture and the fiber mass the temperature and / or the humidity in the tower can be set. 29. A method of controlling the application of glue to fibers according to claim 28, wherein in addition, the temperature of the fibers entered in the tower is recorded and the Setting the temperature and / or humidity in the tower is taken into account. 30. A method for controlling the application of glue to fibers according to one of claims 26 to 29, characterized in that in the tower between the filling opening and Discharge a temperature and / or humidity profile is set. 31. A method for controlling the application of glue to fibers according to one of claims 26  to 30, characterized in that the consistency and / or the temperature of the the fibers to be applied depending on the fiber moisture and / or the temperature of the fibers to be glued is adjusted. 32. A method for controlling the application of glue to fibers according to one of claims 26 to 31, characterized in that the consistency of the fibers applied glue set depending on the air humidity in the tower becomes.