EP-4567216-B1 - PROCESS FOR THE PRODUCTION OF PARTICLE BOARD OR WOOD FIBER BOARD

EP4567216B1EP 4567216 B1EP4567216 B1EP 4567216B1EP-4567216-B1

Inventors

ALLAERT, Laurens
COUDENYS, GEERT
HOFLACK, Veronique
GOEMINNE, Jan
NEL, Koen

Dates

Publication Date: 20260513
Application Date: 20210301

Claims (14)

Process for the production of particle board, MDF board or HDF board, wherein this process comprises the step of recycling particle board material, MDF and/or HDF board material in which recycled chips and/or recycled wood fibers are produced; and wherein the process comprises the step in which the particle board material, the MDF and/or HDF board material is wetted, heated - preferably using steam - and pressurized; wherein this material is kept under pressure and at an elevated temperature for a certain time, wherein the process is free from a step of coating the recycled chips and/or recycled wood fibers with adhesive; wherein this process comprises the step of supplying the recycled chips and/or the recycled wood fibers as base material in a dry production process for particle board, MDF board or HDF board, wherein said base material forms the recycled base material; and wherein also new, adhesive-coated chips and/or new adhesive-coated wood fibers are used as base material, thus forming the new, adhesive-coated base material; wherein the recycled base material is mixed with the new, adhesive-coated base material before this dry production process, wherein the proportion of recycled base material of the combined recycled base material and new, adhesive-coated base material is less than 20 percent by weight.
Process as in claim 1, wherein the recycled chips and/or recycled wood fibers - are conveyed in a - preferably hot - turbulent air stream.
Process as in claim 2, wherein the conveying in the turbulent air stream is followed by one or more separation units, for example for separating off water vapor and hot gases - for example by means of a cyclone - and/or for separating off heavy constituents - preferably by means of the force of gravity.
Process as in any of the preceding claims, wherein the mixing of the recycled base material with the new, adhesive-coated base material takes place before, in or after a blowline which pneumatically conveys the new, adhesive-coated base material to the dry production of the particle board, MDF board or HDF board.
Process as in any of the preceding claims, wherein the proportion of recycled base material of the combined recycled base material and new, adhesive-coated base material is less than 5 percent by weight.
Process as in any of the preceding claims, wherein the weight percentage of recycled base material with respect to the sum of the recycled base material and the new, adhesive-coated base material is constant throughout the thickness of the produced particle board, MDF board or HDF board.
Process as in in any of the preceding claims, wherein the produced particle board, MDF board or HDF board is composed of several layers; and wherein at least one of the surface layers; and preferably the surface layers on both sides of the produced board; comprises less recycled base material than at least one other layer of the board; preferably the at least one surface layer - and more preferably the surface layers on both sides of the produced board - does not comprise recycled base material.
Process as in any of the preceding claims, wherein the process comprises the step of steam explosion of the wetted, heated and pressurized particle board material, MDF and/or HDF board material, in which recycled chips and/or recycled wood fibers are produced during the steam explosion.
Process as in any of the preceding claims, wherein the material undergoes a mechanical dewatering process, for example by pressing - preferably between rollers - or by centrifuging; after the step in which the particle board material, the MDF and/or HDF board material has been wetted, heated - preferably using steam - and pressurized; wherein, if the process comprises the step of steam explosion of the wetted and pressurized particle board material, MDF and/or HDF board material, the mechanical dewatering process is performed after the steam explosion step.
Process as in claim 8 or as in claim 8 and 9, wherein the process comprises the step of mechanically refining recycled wood chips and/or the recycled wood fibers after the steam explosion, preferably by the recycled material being passed through a mechanically operating apparatus, more preferably in which the apparatus comprises grinding discs through which the material is passed.
Process as in any of the preceding claims, wherein the mentioned process steps are carried out in line; and preferably continuously.
Process as in any of the preceding, wherein the particle board material, the MDF and/or HDF board material which is recycled comprises or involves production waste which originates from a process for the production of particle board, MDF board or HDF board as described in any of the preceding claims; and/or wherein the particle board material, the MDF and/or HDF board material comprises or involves post-consumer material.
Process as in any of the preceding claims, wherein this process relates to the production of MDF board or HDF board, wherein the recycling step relates to the recycling of particle board material or MDF and/or HDF board material in which recycled wood fibers are produced; and introducing the recycled wood fibers in the production process of MDF or HDF boards; wherein the recycled wood fibers and also new, adhesive-coated wood fibers are used as base material in the step of producing MDF board or HDF board via a dry process; preferably, wherein the recycled wood fibers are on average finer and/or shorter than the new wood fibers.
Process as in any of the preceding claims, wherein the dry production process for producing particle board, MDF board or HDF board is a continuous production process or is a discontinuous production process.

Description

Technical field The invention relates to a process for the production of particle board or wood fiber board in which wood chips or wood fibers recovered from recycled particle board, from recycled MDF (Medium Density Fiber board) - or from recycled HDF (High Density Fiber board) panels are, at least to some degree, used as base material. Prior art WO2011/077155A1 describes a method for recycling "engineered wood panels", such as wood fiber boards, in which wood fibers are recovered which may be used instead of new wood fibers. The boards or panels are mechanically broken down and mixed with water to form a slurry. This slurry is then heated by passing an electrical current through the slurry. This heating causes a reduction in the strength of the bonds between the wood fibers. This heating may take place at a superatmospheric pressure. After heating, it is possible to release the slurry quickly, for example by spraying it via a valve, drying it and separating the fibers from each other. An apparatus is described for carrying out the method as a continuous process. It is a drawback of this method that the adhesive from the boards dissolves in the bath in which the slurry is heated. This may lead to saturation of the bath, as a result of which the bonds are no longer detached, or the electrical conductivity of the slurry - necessary for heating via the Joule effect - may change. Additives which are necessary to adjust the conductivity may also cause problems. US2003/0056873A1 describes a process for producing wood fiber boards - via recycling of waste from composite wood products - by means of a conventional dry production process for producing wood fiber boards. The process employs a modified treatment in a pre-heater, followed by mechanical refining in a refiner, resulting in recycled fibers. These recycled fibers then constitute at least 20 percent by weight of the fiber boards produced. In the pre-heater, the recycled wood products are chemically treated under pressure and in the presence of steam. It is a drawback of this process that chemicals have to be added in the pre-heater. This may result in corrosion problems. These chemicals also lead to polluted waste streams which have to be treated in a suitable manner. DE4224629 describes a process for recycling panel-shaped elements made of wood products glued together by means of urea-formaldehyde binder and with or without a plastic coating. The process relates in particular to the recycling of wood fiber boards or particle boards. The panel-shaped elements are broken into fragments in a pretreatment step. These fragments are treated in water vapor atmosphere for a certain amount of time - preferably in a saturated water vapor atmosphere - under high pressure and high temperature. As a result thereof, the fragments are transformed into fibrous, chip-like or platelet-like base material which is glued to form new panel-shaped elements. To this end, the recycled fibrous, chip-like or platelet-like base material may be coated with adhesive. Alternatively, chemically modified adhesive may be used, more specifically the urea-formaldehyde glue residues which are still attached to the recycled fibrous, chip-like or platelet-like base material. US5,804,035 describes a process for recovering chips and fibers from waste of wood products, old furniture, production waste, wood products glued together with urea-formaldehyde binders or with other binders which may be hydrolyzed or chemically broken down. These materials are treated at high temperature. In a first step of the process, these materials are impregnated with an impregnating liquid, as a result of which these materials absorb at least 50% of their weight in impregnating liquid. In a second step, heating to between 80 and 120 °C is performed. The materials disintegrated in this way are then sorted by means of sieving or other techniques. WO2003/026859 - by the same applicants and inventors as US5,804,035 - describes a process similar to that in US5,804,035, but which is more economical. It is a drawback of these processes that a mixture or wood fibers and wood chips is obtained which does not make it possible to manufacture high-quality products, since the production of high-quality products requires base material with uniform properties. WO2005/007968A1 describes a method for recovering wood constituents from a board material consisting of a matrix of lignocellulose material bonded by glue. The method comprises treating the material with a combination of electromagnetic radiation and soaking or immersing it in a liquid medium, and recovering constituents. It is a drawback that special equipment is required to generate the electromagnetic radiation to heat up the material, and that it is more difficult to incorporate such a process in a continuous process. WO00/01877 describes a process and an apparatus for treating and recovering wood fiber board waste and particle board waste. Wood fiber board waste and part