Abstract: Disclosed are panels of medium density fibreboard (MDF). The panels comprise wood fibres, the largest dimension of which is 7 mm or below, pressed together with an adhesive. The panels are of a large and thin type, having an aspect ratio of at least 100 and a surface area of at least 1 m2. Typical problems associated with such large and thin panels, e.g. warping behaviour, are addressed by employing wood fibres are made of acetylated wood.

Abstract: Disclosed is a method of purification of utilized acetylation fluid recovered from a process of acetylating wood. The method involves subjecting the recovered acetylation fluid to cooling crystallization. By this method terpene and terpenoid impurities are removed, as well as other impurities. Disclosed is also a method of acetylating wood resulting in acetylated wood and utilized acetylation fluid comprising acetic acid, and purifying the utilized acetylation fluid by cooling crystallization.

Abstract: A process for the production of acetylated wood elements, a cooling system and a wood acetylation plant are described. A process for the production of acetylated wood elements comprises acetylating wood elements and cooling the acetylated wood elements wherein the cooling comprises supplying liquid water to the acetylated wood elements to provide wetted wood elements and exposing the wetted wood elements to a gas flow.

Abstract: The invention is directed to a process for the continuous acetylation of wood elements. The process particularly combines a batchwise impregnation step, with a continuous reaction step. In order to realize this, a collection step is built-in, so as to allow batches of impregnated wood elements to be fed into a reactor in a continuous manner. Very high acetylation contents can be obtained, at a level that had not been achievable before in a continuous and non-catalyzed acetylation process.

Abstract: A system for transferring solid particles from a first environment at a first gas pressure to a second environment at a second gas pressure. The system comprises a first rotary valve having an inlet which is in fluid communication with the first environment, a second rotary valve having an outlet which is in fluid communication with the second environment, and an intermediate housing bounding an intermediate channel, of which an inlet is fluidly connected to an outlet of the first rotary valve and of which an outlet is fluidly connected to an inlet of the second rotary valve. The intermediate channel is fluidly connected to a third environment maintained at a third gas pressure. The third gas pressure is higher than both the first gas pressure and the second gas pressure or lower than both the first gas pressure and the second gas pressure.

Abstract: The invention is directed to a process for the continuous acetylation of wood elements. The process particularly combines a batchwise impregnation step, with a continuous reaction step. In order to realize this, a collection step is built-in, so as to allow batches of impregnated wood elements to be fed into a reactor in a continuous manner. Very high acetylation contents can be obtained, at a level that had not been achievable before in a continuous and non-catalyzed acetylation process.

Abstract: The present invention provides a method for the acetylation of wood comprising treating the wood with an acetylation medium under wood acetylation reaction conditions and drying the acetylated wood, wherein the drying comprises at least two steps, wherein the wood is first dried with a first drying medium and then with a second drying medium.

Abstract: The present invention relates to a method for continuous acetylation of wood elements. The acetylation is conducted with an acetylation medium at a pressure of at least 1.5 barg in a substantially oxygen free environment. Alternatively, the method according to the invention comprises the steps of: (a) feeding wood elements in a substantially oxygen free environment to a continuous acetylation reactor, and (b) treating the wood elements with an acetylation medium in the continuous acetylation reactor under wood acetylation reaction conditions, at a pressure of at least 1.5 barg. The process according to the present invention allows to acetylate wood elements to a high acetyl content in a very efficient way, without compromising on the quality of the material. The acetylated wood elements can be used in the production of medium density fibreboards with superior qualities such as dimensional stability and durability.

Abstract: The disclosure relates to a method for continuous acetylation of wood elements. The acetylation is conducted with an acetylation medium at a pressure of at least 1.5 barg in a substantially oxygen free environment. Alternatively, the method includes the steps of: (a) feeding wood elements in a substantially oxygen free environment to a continuous acetylation reactor, and (b) treating the wood elements with an acetylation medium in the continuous acetylation reactor under wood acetylation reaction conditions, at a pressure of at least 1.5 barg. The process can acetylate wood elements to a high acetyl content in an efficient way, without compromising on the quality of the material. The acetylated wood elements can be used in the production of medium density fibreboards with superior qualities such as dimensional stability and durability.

Abstract: Disclosed is a board made from acetylated mbberwood elements and a method for making same. The acetylated rubberwood elements have an acetyl content of at least 17% and/or are prepared by acetylating mbberwood elements using an acetylation agent in the vapour phase. The invention also pertains to acetylated rubberwood elements prepared by using an acetylation agent in the vapour phase.

Abstract: The present invention provides a method for the acetylation of wood comprising treating the wood with an acetylation medium under wood acetylation reaction conditions and drying the acetylated wood, wherein the drying comprises at least two steps, wherein the wood is first dried with a first drying medium and then with a second drying medium.

Abstract: A system for transferring solid particles from a first environment at a first gas pressure to a second environment at a second gas pressure. The system comprises a first rotary valve having an inlet which is in fluid communication with the first environment, a second rotary valve having an outlet which is in fluid communication with the second environment, and an intermediate housing bounding an intermediate channel, of which an inlet is fluidly connected to an outlet of the first rotary valve and of which an outlet is fluidly connected to an inlet of the second rotary valve. The intermediate channel is fluidly connected to a third environment maintained at a third gas pressure. The third gas pressure is higher than both the first gas pressure and the second gas pressure or lower than both the first gas pressure and the second gas pressure.

Abstract: The disclosure relates to a method for continuous acetylation of wood elements. The acetylation is conducted with an acetylation medium at a pressure of at least 1.5 barg in a substantially oxygen free environment. Alternatively, the method includes the steps of: (a) feeding wood elements in a substantially oxygen free environment to a continuous acetylation reactor, and (b) treating the wood elements with an acetylation medium in the continuous acetylation reactor under wood acetylation reaction conditions, at a pressure of at least 1.5 barg. The process can acetylate wood elements to a high acetyl content in an efficient way, without compromising on the quality of the material. The acetylated wood elements can be used in the production of medium density fibreboards with superior qualities such as dimensional stability and durability.

Abstract: A reactor system for the modification of lignocellulosic materials comprises a reaction vessel, a vacuum connection and an inlet and/or outlet connected to a gas flow loop connected to a heat exchanger and at least one fluid circulation device. Particularly, gas flow loop is arranged so as to allow gas circulation over the diameter of the reaction vessel. The gas flow loop preferably includes a gas distribution device, such as a distribution plate.

Abstract: Disclosed is a reactor system for the modification of lignocellulosic materials. According to the invention, the system comprises a reaction vessel, a vacuum connection and an inlet and/or outlet connected to a gas flow loop connected to a heat exchanger and at least one fluid circulation device. Particularly, gas flow loop is arranged so as to allow gas circulation over the diameter of the reaction vessel. The gas flow loop preferably includes a gas distribution device, such as a distribution plate.

Abstract: Disclosed is a process for the acetylation of wood. The wood to be acetylated is first subjected to an extraction step. The resulting extracted wood particularly has a reduced hemicellulose content. This extracted wood is subjected to contact with an acetylation agent. The extraction can be done with an extraction fluid which is, e.g., water, acetone, ethanol, methanol, or acetic acid. The water can be pure water, such as tap water or demineralised water, or it can be a dilute salt solutions (e.g. water containing ammonium oxalate or sodium sulphite). Hot water extraction is preferred. The resulting acetylated extracted wood, particularly wood elements, have a desirable swelling behaviour at lower acetyl contents than conventional acetylated wood. The wood can be in the form of wood elements, solid wood, or wood veneers.

Abstract: Disclosed is a process for the acetylation of wood, wherein the wood is impregnated with acetylation fluid and heated in stages. It is thereby secured that an acetylation reaction is conducted at a temperature above the boiling temperature of the acetylation fluid, at a stage where the impregnated wood is largely devoid of free acetylation fluid (i.e., acetylation fluid not retained in the wood matrix or in capillaries). Preferably, the process is conducted in a plant having conveyors, such as transportation screws, in the zones in which the separate heating steps are conducted.

Abstract: The disclosure relates to a method for continuous acetylation of wood elements. The acetylation is conducted with an acetylation medium at a pressure of at least 1.5 barg in a substantially oxygen free environment. Alternatively, the method includes the steps of: (a) feeding wood elements in a substantially oxygen free environment to a continuous acetylation reactor, and (b) treating the wood elements with an acetylation medium in the continuous acetylation reactor under wood acetylation reaction conditions, at a pressure of at least 1.5 barg. The process can acetylate wood elements to a high acetyl content in an efficient way, without compromising on the quality of the material. The acetylated wood elements can be used in the production of medium density fibreboards with superior qualities such as dimensional stability and durability.

Abstract: A process for the production of acetylated wood elements, a cooling system and a wood acetylation plant are described. A process for the production of acetylated wood elements comprises acetylating wood elements and cooling the acetylated wood elements wherein the cooling comprises supplying liquid water to the acetylated wood elements to provide wetted wood elements and exposing the wetted wood elements to a gas flow.

Abstract: Disclosed is a method for the continuous impregnation of wood elements, such as wood chips. The method comprises the subsequent steps of subjecting the wood elements to vacuum, to contact with acetylation fluid, and to impregnation pressure. Preferably, the process is conducted in a plant having conveyors, such as transportation screws, in suitable positions between the zones in which the subsequent process steps are conducted. The impregnation method is used in connection with the acetylation of the wood elements, and preferably is followed by a continuous acetylation process conducted in an acetylation reaction zone downstream of the zone where the impregnation is conducted.