Disclosed herein is an environmentally friendly wood protecting method against biological deterioration such as fungal, bacterial and insect damage and non-biological wood deterioration such as weathering. The method comprises contacting a wood material with an aqueous solution of a zirconium salts which is followed by a heat treatment step, providing durable protection of wood against biodegradation and improving several other properties of the treated wood.

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.

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.

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.

A method for chemically modifying a wood part comprising hydroxyl groups comprising: a first step of covalently reacting all or part of the hydroxyl groups with at least one non-polymeric compound comprising at least one group capable of covalently reacting with a hydroxyl group, whereby the wood part is thus covalently linked to residues of the non-polymeric compound(s); after or simultaneously with the first step, a second step of covalently reacting all or part of the residues of the non-polymeric compound(s) with at least one second compound, the first step and the second step being performed in the presence of at least one supercritical fluid.

A flame retardant treatment of a lignocellulosic material, which includes: optionally steam exploding the lignocellulosic material, impregnating the optionally steam-exploded lignocellulosic material, in or with an aqueous solution, from 0.5% to 10% of phytic acid and from 1% to 30% of urea, based on the total weight of the aqueous solution, optionally drying of the impregnated lignocellulosic material, until the impregnated lignocellulosic material has a moisture content from 5% to 20% by weight, cooking the impregnated and optionally dried lignocellulosic material, the resulting flame-retarded lignocellulosic material including a phosphorous content originating from the phytic acid from 0.1% to 10% by weight. Also, the resulting flame-retarded lignocellulosic material and the use thereof for manufacturing flame-retarded composite materials based on plant fibres, woven or nonwoven flame-retarded flexible materials based on plant fibres, and particularly textiles, flame-retarded materials based on wood fibres and/or on wood particles, and particularly flame-retarded wood panels.

A method of treating wood with an organic phosphonate salt in a liquid phase to chemically modify its surface and thus provide protection from microorganisms. The organic phosphonate salts are of Formula III

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wherein R1 is a hydrogen radical or an alkyl or aryl radical having 1 to 20 carbon atoms and R2 is a cation selected from the group of NH4+, H+, Li+, Na+, K+, Rb+, Cs+, Fr+, Cu+, Ag+, substituted or unsubstituted ammonium, phosphonium, and sulfonium, methylpyrrolidinium, isothiazolium, isoxazolium, oxazolium, pyrrolium, thiophenium, pyridinium, pyridazinium, pyrimidinium, pyrazinium, imidazolium, pyrazolium, thiazolium, oxazolium, 1-ethyl-3-methylimidazolium, and triazolium, or a mixture thereof, said method preferably comprising using one or more salt compounds having formula III. Products comprising a raw material having been treated according to the method with one or more organic salts of formula III are also disclosed.

The present invention concerns a process for the recovery of carboxylic acid from a fraction comprising carboxylic acid and impurities, and a process for the manufacture of treated wood, which comprise the step of submitting a fraction containing carboxylic acid and impurities to a gas stripping operation.

A system for treating wood (30), comprising: —a treatment vessel (14) configured to receive at least one wood stack (4) for treatment, and —a stack holding system (2) for holding a wood stack (4), the stack holding system (2) comprising: —a frame (6), configured to support the wood stack (4); —a first element (8), connected to the frame (6) near an upper side of said frame (6), configured to exert a first, downward force on the wood stack (4); and —a second element (10), connected to the frame (6) near a lower side of said frame (6), configured to exert a second force on the wood stack (4) in a direction opposite said first force. The invention also comprises a method for treating wood, using a system for treating wood according to the invention.

A process for acetylation of wood having a density of above 400 kg/m.sup.3, particularly, of Southern Yellow Pine, allows the production of acetylated wood having higher acetylation levels, such as an acetyl content of at least 20% by weight. The acetylated wood has also a low residual acetic acid content, in particular, lower than 1% by weight. The invention is particularly useful for acetylation on industrial scale of pieces of solid wood, preferably, of wood beams.