(19)
(11)EP 1 435 267 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
07.03.2012 Bulletin 2012/10

(21)Application number: 03396117.8

(22)Date of filing:  30.12.2003
(51)Int. Cl.: 
B01F 7/00  (2006.01)
B01F 3/04  (2006.01)
B05D 5/12  (2006.01)
B01F 5/20  (2006.01)

(54)

Foaming method and device

Verfahren und Vorrichtung zum Schäumen

Procédé et dispositif pour le moussage


(84)Designated Contracting States:
DE IT

(30)Priority: 31.12.2002 FI 20022291

(43)Date of publication of application:
07.07.2004 Bulletin 2004/28

(73)Proprietor: Raute Oyj
15551 Nastola (FI)

(72)Inventors:
  • Virtanen, Matti
    Helalantie 8 FI-21800 Kyrö (FI)
  • Rainio, Jouni
    FI-82430 Puhos (FI)

(74)Representative: Helino, Timo Kalervo et al
Papula Oy, P.O. Box 981
00101 Helsinki
00101 Helsinki (FI)


(56)References cited: : 
US-A- 3 965 860
US-A- 4 396 529
US-A- 4 059 714
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description


    [0001] The invention relates to a foaming method according to the introduction of claim 1 and a foaming device according to the introduction of claim 7 used in the production of wood-based sheets such as plywood, battenboard or the like to achieve the necessary foaming of the glue.

    [0002] Plywood as used herein refers to plywood, battenboard or a similar many-layered product that is formed of at least three veneer layers placed one on top of the other or crossways to one another and glued and compressed against one another.

    [0003] Previously known are different foaming methods and devices used in the wood sheet industry to foam glue with the aid of gas, advantageously of air, before it is fed for gluing wood sheets. In known foaming methods and devices glue and air are directed straight into a foaming chamber where the glue is foamed mechanically with the aid of air.

    [0004] The problem of known foaming methods is that the foaming of the glue is not efficient enough. To achieve the desired degree of foaming it is necessary to use very high mechanical foamer rotation speeds, which in turn results in the added disadvantage of heating of the glue mixture.

    [0005] The object of the invention is to remove the above-mentioned disadvantages. In particular the object of the invention is to disclose a new, better and more efficient glue foaming method and device.

    [0006] A foaming method and device according to the invention is characterised by that which is presented in the claims.

    [0007] The base of the invention is a method for foaming glue for production of wood-based sheets in which the gluing substance and the gas are brought into contact with one another and the gluing substance is mechanically foamed with the aid of the gas. According to the invention the gluing substance and the gas are mixed to an essentially homogeneous mixture before mechanical foaming.

    [0008] In mechanical foaming the gluing substance and gas mixture is beat vigorously by mechanical foaming means, whereupon the gluing substance is made to foam with the aid of gas bubbles.

    [0009] In one embodiment of the invention the gas and the gluing substance are mixed by spraying them together simultaneously as several directed partial flows such that as large a contact surface area as possible is produced between the gas and the gluing substance.

    [0010] In one embodiment of the invention the gluing substance and the gas are sprayed in a circular way such that the gas is fed essentially from the centre and the gluing substance from a ring around the gluing substance feed with the gluing substance and gas sprays directed such that the gluing substance and the gas come in contact with one another.

    [0011] In one alternative embodiment of the invention the gluing substance and the gas are sprayed in an circular way such that the gas is fed essentially from the centre and the gluing substance from a ring around the gas feed with the gluing substance and gas sprays directed such that the gluing substance and the gas come in contact with one another.

    [0012] In one embodiment the gluing substance and gas flows are sprayed simultaneously from a feeder surface on which the gluing substance and gas feeder nozzles are arranged alternately and essentially symmetrically across the entire surface area.

    [0013] In one embodiment of the invention air is used as the gas.

    [0014] In one embodiment of the invention a composition is used as the gluing substance that contains resin, foaming agent, filling agent and/or hardener. In one embodiment for the resin, which is the actual gluing substance, advantageously phenol formaldehyde resins, urea formaldehyde resins, amino resins or other similar resins can be used. For the foaming agent, filling agent and hardener different types of substances known in the art and suitable for their intended purpose can be used.

    [0015] Additionally the base of the invention is a device for foaming glue for the production of wood-based sheets in which the device has gluing substance and gas nozzle system, and a foaming chamber and foaming means for foaming the gluing substance mechanically with the aid of a gas, and means for directing the foamed gas out of the device. According to the invention the device has a mixing chamber, in which are arranged gluing substance and gas nozzles of the nozzle system that are directed to mix the gas and gluing substance fed into the mixing chamber into an essentially homogeneous mixture before mechanical foaming.

    [0016] In one embodiment of the invention the nozzle system is arranged to mix by spraying partial flows of gluing substance and gas simultaneously from many directed gluing substance and gas nozzles such that the largest possible contact surface area between the gluing substance and the gas is produced.

    [0017] In one embodiment of the invention the nozzles of the nozzle system are arranged such that the gluing substance nozzles are arranged essentially in the centre and the gas nozzles are arranged in a ringshaped form around the gluing substance nozzles, and the gas and gluing substance nozzles are directed such that the sprayed gluing substance and gas are brought in contact with one another.

    [0018] In one embodiment of the invention the nozzles of the nozzle system are arranged such that the gas nozzles are arranged essentially in the centre and the gluing substance nozzles are arranged in a ringshaped form around the gas nozzles, and the gas and gluing substance nozzles are directed such that the sprayed gluing substance and gas are brought in contact with one another.

    [0019] In one embodiment of the invention the nozzles of the nozzle system are arranged in a matrix construction where gas and gluing substance nozzles alternate across the entire feeder surface area of the nozzle system. The gas and gluing substance nozzles are essentially evenly distributed across the entire surface of the nozzle structure.

    [0020] In a device according to the invention the number of nozzles can vary depending on for example intended use and the conditions for use.

    [0021] Advantageously the gluing substance and gas nozzles of the nozzle system can in principle be directed in any way whatsoever, however such that between the sprays of gluing substance and gas the largest possible contact surface area is produced. Due to a large contact surface area and the mixing of substances that occurs there, as perfect-as-possible mixing of the gluing substance and gas into an even, homogeneous mixture occurs. The nozzles can be directed straight down or straight to the side at a 90-degree angle or at any angle between 0º and 90º.

    [0022] In one embodiment of the invention the foaming means include rotor plates whose rotation speed is advantageously about 500 - 1200 rpm.

    [0023] In one embodiment the foaming device contains a water circulation system, by which the functioning of the foamer can be maintained for example during production standstill without unnecessary foaming of the gluing substance and extinguishing of the foam.

    [0024] Due to the invention a more efficient glue foaming process can be achieved. Due to the forming of a homogeneous gluing substance-gas mixture, the gluing substance foams better with lower rotation speeds and warms up less during the foaming.

    [0025] Due to the invention an even, homogeneous gluing substance and gas mixture can be achieved already before the actual mechanical foaming, whereupon also the foamed glue mixture that is directed onto the surface to be glued is highly homogenous. Additionally the foamed glue mixture is easy and quick to spread on a surface to be glued.

    [0026] A foaming method and device according to the invention are suitable for use in the production of different types of wood-based sheets under various conditions.

    [0027] In the following, the invention is described in detail with the aid of application examples with reference to the accompanying drawings, in which

    Figure 1 shows a foaming device according to the invention, and

    Figure 2 shows in more detail the nozzle system of the device of Figure 1.



    [0028] Figure 1 shows a foaming device that is intended for foaming a gluing substance mixture with the aid of air. The foamed gluing substance is used for gluing wood-based thin sheets and joining them to one another to form for example, plywood.

    [0029] The foaming device in Figure 1 has a nozzle system 1-4, through which the gluing substance and air are fed into the foaming device and a mixing chamber 7, into which the gluing substance are fed and in which occurs the spraying of gluing substance and air to form an adequately homogeneous mixture prior to the actual foaming. The foaming device also contains a foaming chamber 5 and four rotor plates 6 that function as foaming means for foaming the gluing substance mechanically with the aid of air. The centrifugal rotor plates 6 are arranged inside the foaming chamber 5, in which the gluing substance is foamed. The rotation speed of the rotor plates is set to 500 - 1200 rpm. The rotor plates have projections 8 that are arranged symmetrically in five circularly winding rows. These projections 8 aid in the foaming of the gluing substance. For mechanical foaming any kind of mixing organs suitable for foaming can be used, these are not shown in this connection in more detail. Additionally the foaming device contains a pipe or canal 9 for directing the gluing substance out of the device and for spreading the glue.

    [0030] The nozzle system 1-4 of Figures 1 and 2 contains feeder means for both the gluing substance 2 and air 1 as well as seven nozzles 3 for the gluing substance and arranged in the shape of a circle in a ring-like way nozzles 4 for air for feeding the gluing substance and air by spraying them into the mixing chamber 7. Nozzles 3,4 are arranged in the feeder surface area 10 of the nozzle system, such that the gluing substance nozzles 3 are located symmetrically in the middle of the feeder surface area and the air nozzles 4 are arranged in a circular way in one ring around the gluing substance nozzles 3. Both the gluing substance and the air nozzles 3,4 are directed such that a large and good contact area is produced between the partial flows of gluing substance and air and such that the partial flows mix to form an essentially homogenous mixture in the mixing chamber 7 before the actual foaming chamber 5, when the gluing substance and air partial flows are sprayed simultaneously from nozzles 3 and 4 into the mixing chamber 7. Gluing substance 3 and air nozzles 4 are arranged into the mixing chamber 7.

    [0031] Further the device in Figure 1 contains means for raising and adjusting the pressure of air, preferably to approximately 4 bar, prior to feeding it into the foaming device. Additionally the device contains a means for adjusting airflow. Means for adjusting pressure and flow are not shown in the figure.

    [0032] Further the device in Figure 1 contains a gluing substance pump for pumping the gluing substance from the glue storage container into the nozzle system and a flow adjustment meter for adjusting the desired speed of flow. The pump and the flow adjustment meter are not shown in the figure.

    [0033] Additionally the device in Figure 1 contains a temperature measuring probe and a temperature adjustment means, which are not shown in the figure, and are used to adjust the temperature of the gluing substance-air mixture.

    [0034] In a method application according to the invention air, at a pressure of about 4 bar, is directed and gluing substance is pumped at a desired speed of flow into the foaming device shown in Figure 1 through the nozzle system such that the partial flows of gluing substance are sprayed from the nozzles in the centre and air is sprayed in a ring-like way around the sprays of gluing substance into the mixing chamber. The gluing substance and air nozzles are directed in the mixing chamber such that a large contact surface area is produced between the gluing substance and the air, in which case their homogeneous mixing occurs prior to their being directed into the actual foaming area. In the actual foaming area the homogenous gluing substance-air mixture is foamed mechanically with the aid of beating means or in other words rotor plates. The foamed gluing substance is directed to the glue-spreading device for spreading for the gluing of wood-based sheets and for joining these sheets together. Alternatively the gluing substance can, for example during a production standstill or during a temporary disturbance, be directed into so-called foam extinguishing and be later recycled for foaming of the gluing substance.

    [0035] A foaming method and device according to the invention are suitable for various embodiments to achieve the necessary foaming of the glue when producing different types of wood-based sheets.

    [0036] Applications of the invention are not limited to the examples described rather they may vary in the scope of the accompanying claims.


    Claims

    1. A method for the foaming of glue for the production of wood-based sheets, in which the gluing substance and the gas are brought into contact with one another and the gluing substance is foamed mechanically with the aid of the gas, characterized in that the gluing substance and the gas are mixed into an essentially homogeneous mixture prior to foaming by spraying them together as several directed partial flows of giving substance and several directed partial flows of gas, such that the largest possible contact surface area is produced between the gluing substance and the gas.
     
    2. A method according to claim 1, characterized in that the gluing substance and the gas are sprayed in a circular way such that the gluing substance is fed essentially from the centre and the gas from a ring around the gluing substance feed with the gluing substance and gas sprays being directed such that the gluing substance and the gas are brought into contact with one another.
     
    3. A method according to claim 1, characterized in that the gluing substance and the gas are sprayed in a circular way such that the gas is fed essentially from the centre and the gluing substance from a ring around the gas feed with the gluing substance and gas sprays being directed such that the gluing substance and the gas are brought into contact with one another.
     
    4. A method according to one of claims 1 - 3, characterized in that air is used as the gas.
     
    5. A method according to one of claims 1 -4, characterized in that for the gluing substance a composition is used that contains resin, foaming agent, filling agent and/or hardener.
     
    6. A device for foaming glue for the production of wood-based sheets, wherein the device contains a gluing substance and a gas nozzle system (1,2,3,4) for feeding of gluing substance and gas, a mixing chamber (7) for mixing of the fed gluing substance and gas, a foaming chamber (5) and foaming means (6) for foaming the gluing substance mechanically with the aid of gas, and means (9) for removing the foamed gluing substance from the device, characterized in that the gluing substance (3) and gas (4) nozzles of the nozzle system are arranged in connection with the mixing chamber (7), and are directed into the mixing chamber to mix the gas and gluing substance to be fed into an essentially homogenous mixture prior to foaming such that the nozzle system (1,2,3,4) is arranged to mix by spraying partial flows of gluing substance and gas from many directed gluing substance (3) and gas (4) nozzles such that the largest possible contact surface area between the gluing substance and the gas is produced.
     
    7. A device according to claim 6, characterized in that the nozzles (3,4) are arranged such that the gluing substance nozzles (3) are arranged essentially in the centre and the gas nozzles (4) around the gluing substance nozzles (3) in a circular shape.
     
    8. A device according to claim 6, characterized in that the nozzles (3,4) are arranged such that the gas nozzles (4) are arranged essentially in the centre and the gluing substance nozzles (3) around the gas nozzles (4) in a circular shape.
     
    9. A device according to claim 6, characterized in that the nozzles (3,4) are arranged in a matrix construction, in which the gas (4) and gluing substance (3) alternate across the entire feeder surface area (10) of the nozzle system.
     
    10. A device according to one of claims 6 - 9, characterized in that the foaming means include rotor plates (6).
     


    Ansprüche

    1. Verfahren zum Aufschäumen von Klebstoff für die Herstellung von Blättern auf Holzbasis, wobei die Klebesubstanz und das Gas in gegenseitigen Kontakt gebracht werden und die Klebesubstanz mechanisch mit Hilfe des Gases aufgeschäumt wird, dadurch gekennzeichnet, dass die Klebesubstanz und das Gas vor dem Aufschäumen zu einem im Wesentlichen homogenen Gemisch gemischt werden, indem sie in Form mehrerer gerichteter Teilströmungen aus Klebesubstanz und mehrerer gerichteter Teilströmungen aus Gas zusammen gesprüht werden, so dass der größtmögliche Kontaktoberflächenbereich zwischen der Klebesubstanz und dem Gas erzeugt wird.
     
    2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass die Klebesubstanz und das Gas auf einem kreisförmigen Weg gesprüht werden, so dass die Klebesubstanz im Wesentlichen von dem Zentrum und das Gas von einem Ring um die zugeführte Klebesubstanz zugeführt werden, wobei die Klebesubstanz- und Gassprühstrahlen in der Weise gerichtet werden, dass die Klebesubstanz und das Gas in gegenseitigen Kontakt gebracht werden.
     
    3. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass die Klebesubstanz und das Gas auf einen kreisförmigen Weg gesprüht werden, so dass das Gas im Wesentlichen von dem Zentrum und die Klebesubstanz von einem Ring um das zugeführte Gas zugeführt werden, wobei die Klebesubstanz- und Gassprühstrahlen in der Weise gerichtet werden, dass die Klebesubstanz und das Gas in gegenseitigen Kontakt gebracht werden.
     
    4. Verfahren nach einem der Ansprüche 1-3, dadurch gekennzeichnet, dass als Gas Luft verwendet wird.
     
    5. Verfahren nach einem der Ansprüche 1-4, dadurch gekennzeichnet, dass für die Klebesubstanz eine Zusammensetzung verwendet wird, die Harz, Aufschäummittel, Füllmittel und/oder Härtungsmittel enthält.
     
    6. Vorrichtung zum Aufschäumen von Klebstoff für die Herstellung von Blättern auf Holzbasis, wobei die Vorrichtung ein Klebesubstanz- und Gas-Düsensystem (1, 2, 3, 4), um Klebesubstanz und Gas zuzuführen, eine Mischkammer (7), um die zugeführte Klebesubstanz und Gas zu mischen, eine Aufschäumkammer (5) und Aufschäummittel (6) zum mechanischen Aufschäumen der Klebesubstanz mit Hilfe von Gas sowie Mittel (9) zum Entfernen der aufgeschäumten Klebesubstanz aus der Vorrichtung umfasst, dadurch gekennzeichnet, dass die Klebesubstanzdüsen (3) und die Gasdüsen (4) des Düsensystems in Verbindung mit der Mischkammer (7) angeordnet sind und in die Mischkammer gerichtet sind, um das Gas und die Klebesubstanz, die zuzuführen sind, vor dem Aufschäumen zu einem im Wesentlichen homogenen Gemisch zu mischen, so dass das Düsensystem (1, 2, 3, 4) dazu ausgelegt ist, durch Sprühen von Teilströmungen von Klebesubstanz und Gas von vielen gerichteten Klebesubstanzdüsen (3) und Gasdüsen (4) zu mischen, so dass der größtmögliche Kontaktoberflächenbereich zwischen der Klebesubstanz und dem Gas geschaffen wird.
     
    7. Vorrichtung nach Anspruch 6, dadurch gekennzeichnet, dass die Düsen (3, 4) in der Weise angeordnet sind, dass die Klebesubstanzdüsen (3) im Wesentlichen im Zentrum angeordnet sind und die Gasdüsen (4) kreisförmig um die Klebesubstanzdüsen (3) angeordnet sind.
     
    8. Vorrichtung nach Anspruch 6, dadurch gekennzeichnet, dass die Düsen (3, 4) in der Weise angeordnet sind, dass die Gasdüsen (4) im Wesentlichen im Zentrum angeordnet sind und die Klebesubstanzdüsen (3) kreisförmig um die Gasdüsen (4) angeordnet sind.
     
    9. Vorrichtung nach Anspruch 6, dadurch gekennzeichnet, dass die Düsen (3, 4) in einer Matrixkonstruktion angeordnet sind, in der das Gas (4) und die Klebesubstanz (3) über den gesamten Zufuhroberflächenbereich (10) des Düsensystems abwechseln.
     
    10. Vorrichtung nach einem der Ansprüche 6-9, dadurch gekennzeichnet, dass die Aufschäummittel Rotorplatten (6) umfassen.
     


    Revendications

    1. Procédé pour faire mousser de la colle pour la production de plaqués à base de bois, dans lequel la substance collante et le gaz sont portés en contact l'un avec l'autre et la substance collante est expansée mécaniquement à l'aide du gaz, caractérisé en ce que la substance collante et le gaz sont mélangés en un mélange essentiellement homogène avant le moussage en étant pulvérisés ensemble sous la forme de plusieurs flux partiels dirigés de substance collante et de plusieurs flux partiels dirigés de gaz, de façon que la plus grande surface de contact possible soit produite entre la substance collante et le gaz.
     
    2. Procédé selon la revendication 1, caractérisé en ce que la substance collante et le gaz sont pulvérisés d'une manière circulaire de façon que la substance collante soit délivrée essentiellement à partir du centre et le gaz à partir d'un anneau autour de la charge de substance collante, les pulvérisations de substance collante et de gaz étant dirigées de façon que la substance collante et le gaz soient portés en contact l'un avec l'autre.
     
    3. Procédé selon la revendication 1, caractérisé en ce que la substance collante et le gaz sont pulvérisés d'une manière circulaire de façon que le gaz soit délivré essentiellement à partir du centre et la substance collante à partir d'un anneau autour de la charge de gaz, les pulvérisations de substance collante et de gaz étant dirigées de façon que la substance collante et le gaz soient portés en contact l'un avec l'autre.
     
    4. Procédé selon l'une des revendications 1 à 3, caractérisé en ce que de l'air est utilisé à titre du gaz.
     
    5. Procédé selon l'une des revendications 1 à 4, caractérisé en ce que, pour la substance collante, est utilisée une composition qui contient une résine, un agent de moussage, un agent de remplissage et/ou un durcisseur.
     
    6. Dispositif pour faire mousser de la colle pour la production de plaqués à base de bois, lequel dispositif contient un système de buses de substance collante et de gaz (1, 2, 3, 4) pour l'alimentation en substance collante et en gaz, une chambre de mélange (7) pour le mélange de la substance collante et du gaz introduits, une chambre de moussage (5) et des moyens de moussage (6) pour faire mousser la substance collante mécaniquement à l'aide du gaz, et des moyens (9) pour retirer la substance collante expansée hors du dispositif, caractérisé en ce que les buses de substance collante (3) et de gaz (4) du système de buses sont agencées en connexion avec la chambre de mélange (7), et sont dirigées dans la chambre de mélange pour mélanger le gaz et la substance collante devant être introduits en un mélange essentiellement homogène avant le moussage de façon que le système de buses (1, 2, 3, 4) soit agencé pour effectuer un mélange par pulvérisation de flux partiels de substance collante et de gaz provenant de nombreuses buses dirigées de substance collante (3) et de gaz (4) de telle sorte que la plus large surface de contact possible entre la substance collante et le gaz soit produite.
     
    7. Dispositif selon la revendication 6, caractérisé en ce que les buses (3, 4) sont agencées de façon que les buses de substance collante (3) soient agencées essentiellement au centre et les buses de gaz (4) autour des buses de substance collante (3) selon une forme circulaire.
     
    8. Dispositif selon la revendication 6, caractérisé en ce que les buses (3, 4) sont agencées de façon que les buses de gaz (4) soient agencées essentiellement au centre et les buses de substance collante (3) autour des buses de gaz (4) selon une forme circulaire.
     
    9. Dispositif selon la revendication 6, caractérisé en ce que les buses (3, 4) sont agencées selon une construction en matrice, dans laquelle les buses de gaz (4) et de substance collante (3) sont alternées sur toute la surface de distributeur (10) du système de buses.
     
    10. Dispositif selon l'une quelconque des revendications 6 à 9, caractérisé en ce que les moyens de moussage comprennent des plaques de rotor (6).
     




    Drawing