HK1255675B - Process for partial delignification and filling of a lignocellulosic material, and composite structure able to be obtained by this process - Google Patents

Description

The present invention relates to a modification treatment of a ligno-cellulosic material, and any modified ligno-cellulosic material which can be obtained (called composite ) by this treatment, the native architecture of which has been substantially and advantageously preserved. In particular, the invention relates to a process of partial delignification and filling of a structure of a ligno-cellulosic material, and the structure obtained by this process. The ligno-cellulosic material is preferably wood.

Previous technique

It is known that some mechanical properties of wood, such as compressive strength and bending strength, can be improved by impregnating wood with at least one monomer and/or polymer. Such wood impregnated with a monomer and/or polymer is commonly referred to as a wood composite.

A known process for the production of wood composites involves immersing the wood to be treated in a fluid such as an aqueous solution, in which the monomer and/or polymer is dissolved, and pressurising the fluid, so as to incorporate the monomer and/or polymer into the wood.

The aim was to improve this process, for example by using partial vacuum, but no satisfactory solution was found, since all the techniques envisaged were penalised by their long life, mainly because of the difficulty of penetrating the wood pores deeply.

It is also known to impregnate wood with methyl methacrylate (MMA) and then polymerize the monomer thus impregnated. For example, polymerization can be performed using high-energy radiation such as laser or gamma rays. This method is slow, and the use of high-energy radiation is particularly expensive. On the other hand, it was proposed in WO 90/02612 to impregnate wood with a monomer in acidic or basic (alkaline) medium through the use of supercritical (in the state) fluid. This supercritical fluid facilitates the monomeric impregnation of the polymer or porous material.A first method proposed in WO 90/02612 involves the impregnation of wood with an alkaline or acid medium in the presence of a first fluid maintained under supercritical conditions, the digestion of wood impregnated with this medium in the presence of a second fluid maintained under supercritical conditions, in order to extract from wood extractable substances and lignin, which leads to the production of essentially discrete fibres, which are separated from the supercritical fluid and extractable products.The Commission has therefore decided to initiate the procedure provided for in Article 93 (2) of the Treaty in respect of the granting of a Community guarantee to the beneficiary of a loan of EUR 5 million for the construction of a new terminal building in the area of the former Yugoslav Republic of Macedonia.

A second embodiment proposed in WO 90/02612 includes the treatment of a cellulose-containing material with a first supercritical fluid to extract the extractable substances (but not lignin) from the cellulose-containing material; the separation of the supercritical solvent containing the extractable substances from the material to obtain a material with fewer extractable substances; the contact of the cellulose-containing material and fewer extractable substances with a second supercritical fluid containing a polymerizable monomer under conditions sufficient to allow the monomer to be impregnated in the cellulose-containing material; the precipitation of the monomer inside the cellulose and monomer; the precipitation of the cellulose-containing material in this way, which would improve the cellulose-containing material's properties.

This second method is rather reserved for wood pieces of a certain size. Thus, in the examples, pieces of timber are treated with either MMA or styrene. However, the two methods described in WO 90/02612 do not allow the micro-architecture of the wood to be preserved while allowing a filler material to replace enough lignin. The treatment according to this document either produces delignification that is almost complete, and leads to the production of pulp, or delignification that is extremely low or even nonexistent.

More recently, WO 2010/089604 described obtaining parts of ligno-cellulosic material produced by impregnating the material with a formulation based on acetic anhydride at acid pH, then impregnating the material with a formulation based on aqueous organic product, followed by pressurization to impregnate both solutions in the material, then heating to cross-link the organic material into the thus impregnated ligno-cellulosic material. This allows a piece of ligno-cellulosic material to be made from a hardened composite. However, since the filling of the material with the organic product can only be partially superficial (i.e. a small thickness on the surface), this can only give a relatively improved mechanical treatment of the parts, which can improve the strength of the parts.

The production of transparent paper sheets with a thickness of less than 100 μm has also been described (Advanced Materials, 2009, 21, 1595-1598, Optically transparent nanofiber paper, Nogi et al., 2009), including by using a monomeric compound of acrylic resin (tricyclodecane dimethyl dimethylacrylate -TCDDMA-).

WO 2014/113884 describes a process for treating wood parts by contacting two solutions A and B, respectively sources of anions and cations, in order to delignify wood under exothermic conditions, leading to the production of a pulp.

Consequently, the methods known to date for impregnating wood, or any other ligno-cellulosic material, to make it a more resistant material are complicated to implement, relatively expensive and far too slow to realistically envisage industrial production of a wood composite material.

The need for a process for processing a structure of wood-cellulosic material, preferably wood, so as to obtain a structure which retains the architecture of wood and is made of a material with improved mechanical properties, in particular in terms of bending strength and compressive strength, compared with wood-cellulosic material before treatment remains.

One of the first objects of the invention is to overcome the disadvantages mentioned above of the state of the art methods, and in particular to provide a simple to implement process for processing ligno-cellulosic material, which allows to obtain a material that preserves the architecture of wood and with improved mechanical, chemical and/or optical properties.

Summary of the invention

The invention thus concerns, in the first instance, a process for processing a structure of ligno-cellulosic material, the ligno-cellulosic material being preferably wood, which consists of the following steps: (1) at least one step of soaking the structure of the ligno-cellulosic material in at least one fluid to dissolve at least 40% and at most 85% by weight of the lignin present in the material; (2) at least one step of washing the structure from step (1) with at least one organic fluid to discharge the dissolved lignin from the soaking step (1) so as to produce a partially de-lignified structure; (3) at least one step of filling the partially de-lignified structure from the washing step with at least one filling compound so as to incorporate a partially de-lignified structure into the material; and (3) at least one step of finishing the composition of the partially de-lignified structure from the soaking step to obtain a structure from a network of three-dimensional cellulose-filled fibres.

The invention also concerns, in a second aspect, a composite material structure comprising lignin, hemicellulose, cellulose and at least one filler compound, which can be obtained by applying the treatment process in the first aspect of the invention, in which the composite material forms a three-dimensional network of a processed filler compound incorporated into a cellulose and lignin structure.

According to one embodiment, the invention relates in particular, in this second aspect, to a composite material structure comprising lignin, hemicellulose, cellulose and at least one filler compound, that structure being obtained by implementing the treatment process in the first aspect of the invention, in which the composite material forms a three-dimensional network of processed filler compound incorporated into a cellulose and lignin structure.

Finally, the invention relates, in a third respect, to a part comprising at least one composite material structure according to the invention, such part being a piece of furniture or part of a piece of furniture, a building element, a part of an automobile or an aircraft part.

The process of processing a structure of a ligno-cellulosic material according to the invention involves the novel and innovative combination of partial delignification of the structure followed by a filling with a compound which is stabilized within the delignified structure. This combination is advantageous in obtaining a composite material which substantially preserves the structure of the material and is formed by two interpenetrating networks, in which the architecture of the ligno-cellulosic material has been altered at the nanoscale but substantially preserved at the microscopic and macroscopic scales. Consequently, the properties of the ligno-cellulosic material, which has been transformed into a composite material according to the invention before treatment, are notably improved, both mechanical and chemical/operational, compared to the material before treatment.

Without being bound by any theory, the applicant believes that this is because the composite material has stronger molecular bonds between fibres of the ligno-cellulosic material than those existing in the ligno-cellulosic material in the native (or natural) state, including through the processed filler compound. Thus, the composite material advantageously combines the properties of the ligno-cellulosic material with those of the processed filler compound (most often of cross-linked polymer type or not), as it is composed of dense structure of ligno-cellulosic material in which the transformed composite material plays the role of a continuous chemical binder between the fibres of the cellulosic material and the nano-cellulosic material, thus adding the chemical bonding points of the nano-cellulosic material and the physical bonding points of the cellulosic material. This is more efficient by adding the physical and nanoscale contact points of the cellulosic material.

The applicant considers that the densified structure also results from better organisation (and therefore improved compactness) and increased crystallinity of the ligno-cellulosic structure compared to the native ligno-cellulosic structure (in which lignin is generally amorphous).

Thus, in the end, the composite material includes a ligno-cellulosic material of much greater mechanical strength than in the native state. Thus, the composite material can be described as hardened . This explains the great qualities of the composite material, and its improved mechanical, chemical, and/or optical properties compared to the native ligno-cellulosic material.

Detailed description of the invention Definitions of the term

The structure of the ligno-cellulosic material according to the invention is derived from the architecture of wood, some elements of which are briefly described below.

At the atomic scale, wood consists of about 50% carbon atoms, 6% hydrogen atoms and 40% oxygen atoms, as well as traces of inorganic compounds and organometallic complexes. More specifically, wood is composed of 60 to 75% carbon hydrates in the form of cellulose and hemicellulose, as well as 18 to 35% lignin.

The plant cell, consisting of a cavity, lumen, wall, and intercellular sap transport channels, called punctuations, is the building unit of the microscopic scale. In the living state, the cavities of the wood cells near the bark of the tree provide the sap transport from the roots to the ends of the tree, while the walls provide the mechanical resistance functions. The cells die as the tree grows, providing only the wood supporting the wood of the tree. The main walls of the cell are made up of the solid nano-nine-layered layer of three layers (the middle layer, the primary layer and the secondary layer) which assure the sap transport from the roots to the ends of the tree, while the walls provide the mechanical resistance functions. The majority of these layers are made up of cellulose and cellulose.

The respective amounts of lignin, cellulose and hemicellulose vary depending on the wood, tree and part of the tree being considered. Cellulose is partially semi-crystalline while lignin is amorphous. Lignin is dark brown while cellulose and hemicellulose are rather white. These three polymers are entangled so that a nanoscopic porosity exists in the material, instead of molecules called extractibles. Although anchored in the material (mainly by physico-chemical bonds), these molecules are independent of the maternal-cellulose network.

The term extractibles is a very broad set of molecules resulting from secondary metabolites synthesized during the growth of ligno-cellulosic material. They are present in relatively small amounts (between 5 and 10% by weight) as mixtures, sometimes complex, and highly variable, which are related to the nature of the ligno-cellulosic material. The variability of these molecules (in quantity and quality) is significant. The composition and climate of the soil-cellulosic material including its large amount of extractible ligno-cellulosic material, is greatly influenced by the amount of chemical.

Extractibles are a group of molecules with a wide variety of structures, functions and properties, which can be polar or apolar, hydrophilic or hydrophobic, linear, mono-aromatic or poly-aromatic.Extractibles include the following compounds: waxes and fats, terpenes (monoterpenes, diterpenes, triterpenes, sesquiterpenes, diterpenic acids) and phenolic compounds (derivatives of phenols, lignans, stilnes, flavonoids, biflavonoids, condensed tannins, hydrolysable tannins).

Extractibles provide additional chemical protection for wood, as they are often involved in the defense mechanisms of the ligno-cellulosic material against external attacks such as fungi, enzymes, xylophage insects, microbes, and are also responsible for the odor, part of the colour, and the inherent lifespan of the ligno-cellulosic material.

The architecture of a ligno-cellulosic material is called native (or natural ) when the material, regardless of the scale of organization at which it is observed, has properties similar to those found in untreated ligno-cellulosic material.

The term space of wood architecture , also referred to more simply as space or volume (corresponding to a substantial absence of matter) thereafter, refers to the microscopic cavities of wood and the punctuations that connect them, filled with sap in living cells, but also to the nanoscopic spaces between the chains of entangled polymers contained in the walls of cells.

structure of ligno-cellulosic material means, according to the invention, a three-dimensional object made of ligno-cellulosic material, and having a certain volume (three-dimensional) of at least about 2 cm3. It is a macroscopic object that has substantially retained the architecture of the native ligno-cellulosic material. Thus, preferably, the structure of ligno-cellulosic material comprises at least a dimension of at least 5 mm and not more than 40 cm. When the ligno-cellulosic material is wood, the structure can typically be a wood cut (cross cut, longitudinal cut, radial cut) for example 5-7 mm thick.

In particular, the structure of the ligno-cellulosic material can be a finishing element, a secondary element or a primary element.

finishing element means, according to the invention, a three-dimensional object of which one of the dimensions, usually the thickness, is much smaller than the other two dimensions and typically at least about 0.5 mm, preferably at least about 1 mm, even more preferably at least about 2 mm and even more preferably at least about 5 mm. This object is usually chosen from the group formed by the wood sheets, markings the coatings, the plates, the plates and plating, preferably the plating and plating. thick veneer . secondary work means, according to the invention, a three-dimensional object of which one of the dimensions, usually the thickness, is much smaller than the other two dimensions and typically at least about 1 cm, preferably at least 1.5 cm, still more preferably at least about 2 cm. This object typically corresponds to the secondary work in the building, i.e. it is chosen from the group formed by the sidings, cups, ledges, pedestals, parquet floors, partitions, panels, roofing and joists.This is pretty much the same as the term timber in English.

This object corresponds to the first work (or large work) in the building, i.e. it is chosen from the group formed by the posts, beams, lattice structures and frames. This corresponds to the term lumber. This object also includes cross-laminated wood panels also called solid panels (CLT), which are panels composed of three monolithic panels with at least 8 cm of cross-section between the two sides. These panels are generally made of at least 6 to 8 cm of monolithic fibers, and some are at least 6 to 8 cm wide.

building element means, according to the invention, an element of the technical field of building, i.e. a building element, which is either a finishing element, a secondary work element or a first work element.

By fluid , we mean according to the invention liquid or gas. By organic , we mean according to the invention containing mainly carbon, hydrogen with oxygen, and nitrogen.

The invention means that the structure is brought into contact with the fluid through most, preferably almost all, of its outer surface. Thus a dip does not necessarily mean a dip; it can simply be a partial or total contact with a fluid. The dip can result in a partial or total impregnation by the fluid by the action of at least one of the following forces: diffusion forces, capillary forces, gravity forces, agitation forces outside the compound undergoing the dip or any other forces acting on the fluid's ability to move.

Green wood is wood that still contains free water molecules or is linked to the cell network, such as freshly cut wood. Thus, a freshly cut wood is a wood that usually contains 100% relative humidity, while a wet wood by definition contains only water molecules in the cavities of the cell network, or about 30% relative humidity. The test shall be carried out on the test vessel in accordance with the requirements of paragraphs 6.1.3 and 6.1.4.At the time of felling, wood can contain more water than wood-based material; sometimes twice as much in some poplars. The relative humidity is then over 100%. According to the CNDB, the saturation point of wood fibres, below which the wood set is manifested, is about 30% for all species. dry wood means wood that has undergone treatment to reduce the percentage of water retained in cell walls, so that its humidity level is generally between 0 and 30%.

By A and/or B , we mean A, or B, or A and B.

% by weight means the percentage by mass. Unless otherwise specified, any percentage shown in this description is a percentage by mass.

Other, of a thickness of

The wood used for the production of wood fibres is wood, which can be either green, wet or dry, depending on the design. For example, it can be wood used after storage for a longer or shorter period (from a few days to a few years). This wood can have been processed after cutting, i.e. cut, felled, re-worked, stripped of bark, silt or hardwood, or be engineered wood.

It can also be an old wood, i.e. wood which has already been used as building wood, for example.

Virtually all wood species, also known as wood families, with a lignin content of between 15 and 35%, preferably between 18 and 32%, and even more preferably between 20 and 30% by weight, can be treated by the process according to the invention, whether they belong to the angiosperm or gymnosperm families, whether they are oak or ash wood, or more conventional wood used in furniture or even in the field of building (construction), or wood for furniture such as ash, building wood such as oak, beech or oak or more malleable wood used for the cutting of pine or oak pieces or for the moulding of some species such as balsa or balsa.

The most commonly used resinous wood is the pine, pine, spruce, fir, spruce, pine, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce, spruce

The wood of the leafy hazel is chosen from among the angiosperms, preferably from the group formed by the elder, birch, balsa, beech, ash, eucalyptus, cottonwood, hevea, poplar, tremble, willow, false-acacia robin, oak, mahogany, guatambu, fraque, meranti, linden, chestnut, maple, marron, elm, hazelnut, walnut, orange, platane, sycamore, apple, pear, lemon and tulip, preferably the elder, oak, poplar, marble, frost, cotton, oak, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, maple, map

Each of these essential oils may include many species, for example, the essential oils of pine trees include more than 100 species, such as sea pine and wild pine, and the essential oils of oak trees include many subspecies, such as red oak (American) or white oak (European).

Each wood species has its own architecture and chemical identity (i.e. respective amounts of lignin and hemicellulose, length of cellulose fibres, and extractibles) and within the same tree, different parts of the wood (such as the tree trunk or the duramen) may also have different physicochemical properties depending on the species.

But ligno-cellulosic material can also be any material formed from a three-dimensional network of cellulose, and lignin, such as straw, natural textiles (such as flax or hemp), all forest biomass, including bamboo, high-yield pulp, paper, cardboard, and cotton, provided that such material is in the form of a structure with some mechanical strength and micro-architecture suitable for being reclaimed by a filler compound that partially replaces lignin. This material usually also contains at least one polysaccharide.

Optional pre-treatment stage

According to the invention, the soaking step (1) may be preceded by a pre-treatment step, usually to partially extract extractables, involving at least one sub-step of pre-soaking a structure of a ligno-cellulosic material with at least one organic fluid, usually to dissolve some of the extractables present in the material; followed by at least one sub-step of pre-washing the structure from the pre-soaking sub-step with at least one organic fluid, so as to evacuate the dissolved compounds from the pre-soak sub-step.

The structure of the ligno-cellulosic material resulting from the pre-treatment step is the structure to be treated by the treatment process according to a first aspect of the invention.

Each of these pre-soak and pre-wash sub-steps may be repeated once or several times as necessary, independently of the other step provided that the final sub-step is a pre-wash sub-step.

This preliminary step makes it possible to dissolve extractibles by releasing anchorages, particularly physical ones, and then extract them.

This preliminary step makes it advantageous to facilitate partial delignification during the subsequent steps of soaking (1) and washing (2) according to the invention.

The pre-soaked sub-step allows for a controlled and partial extraction of the extractibles present in the ligno-cellulosic material. The extraction may not be carried out in a homogeneous manner within the ligno-cellulosic material, particularly depending on the operating conditions of this sub-step and the nature of the ligno-cellulosic material. For example, in the case of the preferred ligno-cellulosic material, wood, spring wood is often more sensitive to the pre-soaked sub-step than summer wood.

This sub-step makes it possible to conserve sufficient extractibles within the ligno-cellulosic material to preserve the architecture of the ligno-cellulosic material, but also to chemically weaken the architecture of the ligno-cellulosic material in order to facilitate the action of the fluid during the soaking stage (1), i.e. to facilitate further partial delignification.

The pre-soak sub-step is generally performed under operating conditions similar to those of the soak (1) step described below, under conditions which allow the desired partial extraction of extractables from the structure of the ligno-cellulosic material.

In this case, a first organic pre-soaked fluid is intended to saturate the structure of the ligno-cellulosic material first, and then in a second step this saturated structure is brought into contact with a second organic pre-soaked fluid. The osmotic pressure between the two fluids creates a spontaneous movement of the two fluids towards each other for a return to equilibrium by a mixture of the two fluids.

In the case of the osmotic process, it is preferable that the structure of the ligno-cellulosic material be dry (i.e. at a relative humidity of 0-30%) before it comes into contact with the first fluid of the pre-soak sub-step, and that this contact be made under vacuum and with heating.

The first and second fluids of the pre-soak sub-step are advantageously either both aqueous or both non-aqueous, so as to promote their miscibility.

A greater difference in properties between these two fluids, such as a difference in solvent, pH, salinity, and/or the potential compound (s) in solution in this organic fluid, generally results in a faster return to equilibrium.

For example, a first pre-soaked solution was made of ethanol, in which a sample of ligno-cellulosic material was bathed under vacuum and at room temperature for 8 h. The sample was then brought into contact with a second aqueous pre-soaked solution containing baking soda at pH=12, under vacuum and at a constant temperature of 70°C, for 1 h. The resulting sample was washed with 3 to 4 sets of hot water at 40-50°C and aqueous baking soda at pH=12, until a clear washing water was obtained.

As is obvious to the professional, the quantity and nature of the extractibles dissolved in this sub-step of pre-soak depends on the nature of the ligno-cellulosic material, but also on the nature of the two organic fluids in this sub-step.

However, this sub-step of pre-soak may specifically target certain extractibles, in which case some solvents may be preferred. For example, it may be desirable to selectively extract water-soluble or fat-soluble compounds. Indeed, partial extraction of fat-soluble compounds, such as fats, may promote hydrophilia within the structure of the ligno-cellulosic material and thus facilitate subsequent steps (1) and (2) if these are carried out by means of an organic liquid. Similarly, partial extraction of non-hydrosoluble compounds, such as cirno-cellulosic or sugar, may facilitate hydrophilia within the structure of the organic liquid and therefore subsequent steps (1) and (2) if these are carried out by means of an organic liquid.

The pre-washing sub-step allows the extraction of the dissolved extractibles present in the ligno-cellulosic material following the pre-soak sub-step, in particular to prevent the presence of dissolved extractibles within the structure from limiting the action of the fluid and hence the delignification during the soak step (1).

The pre-wash sub-step may be carried out under similar operating conditions to the wash step (2) described below, so that the pre-wash sub-step fluid may be any organic fluid used during the wash step (2) described below.

For example, the pre-washing sub-step may be performed under vacuum and at room temperature with an aqueous solution alternating with an aqueous solution of baking soda at pH=12, alternating every 15 min, for a total of 1 hour.

Extractibles, such as terpenes, which are dissolved and then extracted from the structure of the ligno-cellulosic material by the pre-processing step of the invention, can be advantageously recovered in the process of the invention, in a recovering process specific to each family of dissolved molecules, typically on an industrial scale, for example for the manufacture of a chemical compound in the pharmaceutical or cosmetic industry.

The test shall be carried out in accordance with the instructions given in Appendix 1 to this annex.

The soaking step (1) allows partial and controlled dissolution of some of the lignin present in the material, i.e. partial delignification. Delignification may not be achieved in a homogeneous manner within the ligno-cellulosic material, particularly depending on the operating conditions of steps (1) and (2) and the nature of the ligno-cellulosic material.

The partial delignification according to the invention excludes the production of a fibre pulp from ligno-cellulosic material.

The soaking step (1) allows both to retain enough lignin (in native form or regenerated after recombination of radicals formed during lignin degradation) within the material to preserve the architecture of the native ligno-cellulosic material, and to extract enough lignin through the fluid to release within the ligno-cellulosic material architecture the space in which the new step filling compound will fit (3). Thus, the presence of residual lignin within the structure does not limit the filling of the existing spaces, microscopic or nanoscopic, nor those created during filling (1) by the filling (2) and the filling of the new phase by the filling of the phase (3).

The partial delignification performed in steps (1) and (2) may be used, although not as its primary purpose, to extract other components of the ligno-cellulosic material such as extractibles if they have not been extracted in the optional previous step.

The soaking (1) step can be carried out at room temperature, or by heating in the presence of a heat source, at atmospheric pressure, under vacuum or under pressure or by alternating use of these different conditions, as is known to the professional.

The process of soaking results in partial or total permeation by the fluid (which may be liquid and/or gaseous) usually by the action of at least one of the following types of forces: diffusion force, capillary force, gravity force, external agitation force of the structure or any other force acting on the fluid's ability to move.

The soaking step (1) can be performed in one or more steps, i.e. the contact with the fluid can be done in one or more steps.

The amount of lignin extracted from the ligno-cellulosic material depends on the material concerned, depending on whether it is for example resinous wood, hardwood or annual grass.

Thus, in the case of wood fibres, the lignin content in the structure dissolved during the soaking stage is usually 50 to 85%, preferably 50 to 75% by weight (1). In the case of wood fibres, however, the lignin content in the structure dissolved during the soaking stage is usually 40 to 60%, preferably 45 to 55% by weight (1). The craftsman may even adapt the conduct of steps (1) and (2) according to the structure of the fibres concerned.

The soaking step (1) must allow the desired amount of lignin to be retained in the structure and not significantly impair the micro-architecture of the ligno-cellulosic material.

The fluid can be any solvent or mixture of organic solvents that allows de-lignification.

Depending on one embodiment, the fluid is a complex system composed of a majority solvent, called the primary or main solvent, and at least one minority solvent, called the co-solvent.

The parameters of the primary solvent (i.e. pH, dielectric constant, ionic strength, acidity, basicity, oxidant or reducing character) can be adapted by adding at least one compound which allows specific solvating properties.

In the case where the main solvent is water, the complex system is an aqueous solution (also called solution), containing water and at least one solute, which may be a co-solvent and/or a dissolved solid compound, such as a salt.

Complex systems can be miscible, micellate or biphasic systems and can themselves be used in mixtures and/or in series. (i) an acid or basic solution, whether or not aqueous; (ii) an acid or basic oxidizing solution, whether or not aqueous; (iii) a pure ionic liquid; (iv) an ionic liquid mixed with a co-solvent; (iv) an ionic liquid containing one or more enzymes; (iv) an ionic liquid mixed with a co-solvent containing one or more enzymes; (v) an ionic liquid mixed with a co-solvent and a liquid; (iv) an ionic liquid mixed with a co-solvent, a fluid and containing one or more enzymes; (v) a fluid containing at least one biological organism such as bacteria, fungal microbes or (vi) any combination of elements.

The first compound mentioned in each element (i) to (vi) of the list is usually the majority, i.e. at least 50% by weight.

Depending on the method of manufacture, the fluid in the soak (1) is an organic solution, which can have any pH. Preferably, the organic solution is acidic, usually below 6.5 pH, preferably below 4.5 pH, or basic, above 7.5 pH, preferably above 9.5 pH.

In addition to water, the organic fluid of the washing step (2) may contain any liquid traditionally used as a solvent in chemistry. Pure solvents and co-solvents of choice are generally chosen from the group consisting of ethyl acetate, butyl acetate, methyl acetate, ethyl acetate, acetone, acetic acid, citric acid, formic acid, nitric acid, oxalic acid, methanolic acid, acetic anhydride, butanol, butanol, cyclohexane, melanoheptane, cyclopropane, dichlorophenol, dichlorophenol, propane, acetylamine, diethyl acetate, diethyl alcohol, propanol, glyphosate, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol, propanol

Acid means any compound, alone or in combination, which can release a proton, such as mineral or organic acid, in liquid form or as a dissolved solid salt. These include carboxylic acids, salts derived from carboxylic acids and anhydrides such as non-phenolic organic acids such as acetic acid, ascorbic acid, benzoic acid, boric acid, carbonic acid, chlorinated citric acid, vanadium cyclic acid, dichloroacetic acid, formic acid, hydroxyzoic acid, vitriol; their residues include: hydrofluoroic acid, phosphoric acid, nitric acid, phenol, sulfuric acid, sulfuric acid, sulfuric acid, sulfuric acid, sulfuric acid, triiodothyronine, triiodothyronine, triiodothyronine, triiodothyronine, triiodothyronine, triiodothyronine, triiodothyronine, triiodothyronine, triiodothyronine, triiodothyronine, triiodoroic acid, triiodoroic acid, triiodoroic acid, triiodoroic acid, triiodoroic acid, triiodic acid, triiodoroic acid, triiodic acid, triiodic acid, triiodic acid, triiodic acid, triiodic acid, triiodic acid, triiodic acid, triiodic acid, triiodic acid, triiodic acid, triiodic acid, triiodic acid, triiodic acid, triiodic acid, triiodic acid, triiodic acid, triiodic acid, triiodic acid, triiodic acid, triiodic acid, triiodic acid, triiodic acid, triodic acid, triodic acid, triodic acid, triodic acid, triodic acid, triodic acid, triodic acid, triodic acid, triodic acid, triodic acid, triodic acid, triodic acid, triodic

methybutane is any compound, whether alone or in a mixture, which can accept a proton, whether in liquid form or as an inorganic salt in solution. These include amines, amides, alkaline salts such as sodium acetate, sodium amide, 3-amino-3-methylpentane, ammonia, aniline, azetidin, bromopyridine, lithium butyl, cadaverine, 2-chlorophenol, 3-chlorophenol, 4-chlorophenol, choline, cyclohexylamine, lithium terthilamide, lathylamine, diethylamide, barilamine, 2,4-dimethylamine, 1,2-dimethylamine, 1,2-hydroxylamine, 1,2-hydroxylamine, 2-methylamine, 2-hydroxylamine, 1,2-methylamine, 2-hydroxylamine, 1-methylamine, 2-hydroxylamine, 1-methylamine, 2-hydroxylamine, 1-methylamine, 2-hydroxylamine, 1-methylamine, 2-hydroxylamine, 1-hydroxylamine, 2-hydroxylamine, 1-methylamine, 2-hydroxylamine, 2-hydroxylamine, 1-hydroxylamine, 2-hydroxylamine, 2-hydroxylamine, 2-hydroxylamine, 2-hydroxylamine, 2-hydroxylamine, 2-hydroxylamine, 2-hydroxylamine, 2-hydroxylamine, 2-hydroxylamine, 2-hydroxylamine, 2-hydroxylamine, 2-hydroxylamine, 2-hydroxylamine, 2-hydroxylamine, 2-hydroxylamine, 2-hydroxylamine, 2-hydroxylamine, 2-hydroxylamine, 2-hydroxylamine, 2-hydroxylamine, 2-hydroxylamine, 2-hydroxylamine, 2-hydroxylamine, 2-hydroxylamine, 2-hydroxylamine, 2-hydroxylamine, 2-hydroxylamine, 2-hydroxylamine, 2-hydroxy

Oxidative compound a compound, alone or in combination, that has an oxidizing action, i.e. that is capable of capturing one or more electrons. This oxidant may be a derivative of chlorine chemistry such as sodium chlorite, calcium chloride, sodium chloride, dichloride, bleach, calcium hypochlorite, sodium hypochlorite, any peroxide compound such as hydrogen peroxide, or any compound derived from the prior action of a peroxide compound on another molecule, such as a peracid, resulting from the reaction of a peroxide, hydrogen peroxide, and an acid.Peroxide compounds are compounds of general formula ROOR', where each of R and R' is a hydrocarbon chain such as an alkyl, alkyloyl, alkyloxycarbonyl, aryl, aryloyl, or aryloxycarbonyl chain and their mixtures, which may or may not be substituted. Examples of hydrocarbon chains are: for an alkyl chain: methyl, ethyl, propyl, butyl, t-butyl, and pentyl; for an alkyloyl chain: ethyl, propyoyl, butyl aryloyl, and pentoyl; for an alkyloyl chain: carbonate esters such as ethyl, propylene, butyl, and aryl carbonate; for a chloryl chain: benzyl, naphthyl, phenyle, naphthyl, naphthyl, and naphthyl, and naphthyl, and naphthyl, and naphthyl, and naphthyl, and naphthyl, and naphthyl; for an alkyloyl chain: carbonate esters such as propylene, propylene, butyl, naphthyl, and naphthyl; for an alkyloyl, and naphthyl, and naphthyl, and naphthyl.

Such an oxidizing compound may be added to an acid or base described above in order to make an oxidizing acid solution or an oxidizing base solution according to the invention. Acids and bases may in some cases exhibit oxidizing properties themselves, but it is possible to add an oxidizing compound to them to strengthen this property. According to the invention, an oxidizing compound added to the acid or base compound may react independently or form new reactive entities. Thus, for example, a peroxide may be combined with a carboxylic acid to form a peracid, such as peracid formic, peracid acetic or persulfuric acid.

The term reductant refers to a compound, alone or in combination, that has a reducing action.Aldehydes, sodium dithionite, hydroquinone, sodium hydride, sodium sulfite, sodium thiosulfate, and their mixtures are all included in the family of aldehydes.

Such a reducing agent may be added to an acid or base described above.

Preferably, the soak fluid (1) may be chosen from: an acidic oxidizing aqueous solution containing a mixture of an acetic acid solution or an oxidizing agent such as hydrogen peroxide, or an acidic aqueous solution containing hydrogen bromide, sulphuric acid or phosphoric acid; a basic oxidizing aqueous solution containing a mixture of a basic solution such as sodium hydroxide, an aqueous liquid containing monoethanolamine, or potassium hydroxide with an oxidizing agent such as sodium chlorite.

The fluid may also be an ionic liquid and/or a biological organism such as an enzyme, a bacterium, a microbe or a fungus. Ionic liquid means, according to the invention, any organic salt solution with a melting point below 100°C, generally liquid at room temperature, and having a low vapour pressure, i.e. a boiling point between 200°C and 400°C.

A preferred ionic liquid according to the invention, used alone or in a mixture, is preferably chosen from amino-cationic ionic liquids such as the cholinium, imidazolium, N-methyl-2-pyrrolidinium, pyridinium, pyrrolidinium cations and their mixtures, preferably imidazolium. The counter-ion is preferably chosen from acesulfamate, acetate, bromide, chloride, formate anions and their mixtures, preferably acute abions such as aculfamate, acetate, bromide, formate, and their mixtures. Particularly preferred is the 1-alkyl-3-alkyl imidazolium type cation, where the alkyl groups each consist independently of 1 to 6 carbon atoms, such as 1-alkyl-3-methyl-butyl imidazolium or 1-alkyl-3-butyl imidazolium.

Thus, the ionic liquid according to the invention can be selected from 1-ethyl-3-methyl imidazolium acesulfamate, 1-butyl-3-methyl imidazolium acetate, 1-ethyl-3-methyl imidazolium acetate, 1-butyl-3-ethyl imidazolium bromide, 1-butyl-3-methyl imidazolium bromide, 1-ethyl-3-methyl imidazolium bromide, cholinium glycine, choline lysine, N-methyl-2-pethrolidinium acetate, pyridinium formate, pyridolidinium acate, pyridolidinum formate and their mixtures. The most commonly used ionic liquids are 1-methyl-3-methyl bromide, 1-methyl-3-methyl bromide, 1-methyl-3-methyl bromide, 1-methyl-3-metyl bromide, 1-methyl-3-metyl bromide, 1-methyl-3-metyl bromide, 1-methyl-3-metyl imidazolium bromide, 1-methyl-3-metyl bromide, 1-methyl-3-metyl bromide, 1-methyl-3-metyl bromide, 1-methyl-3-metyl bromide, 1-methyl-3-metyl bromide, 1-methyl-3-metyl-metyl imidazolium bromide, 1-methyl-3-metyl bromide, 1-methyl-3-metyl-metyl-metyl-metyl-metyl-metyl-metyl-metyl, 1-metyl-metyl-metyl-metyl-metyl-metyl-metyl-metyl, 1-metyl-metyl-metyl-metyl-metyl-metyl-metyl-metyl, 1-metyl-metyl-metyl-metyl-metyl-metyl-metyl-metyl-metyl, 1-metyl-metyl-metyl-metyl-metyl-metyl-metyl-metyl-metyl-metyl-metyl, 1-metyl-metyl-metyl-metyl-metyl-metyl-metyl-metyl-metyl-metyl-metyl-metyl-metyl-metyl

The ionic liquid can also be an ionic liquid derived from an amino acid such as cholinium glycine or cholinium lysine.

The ionic liquid can also be synthesized from a molecule derived from one of the steps of the treatment process of the invention, in particular the soaking step (1). This makes it advantageous to optimize the by-products generated during the process. For example, ionic liquids synthesized from aromatic aldehydes derived from lignin or hemicellulnin, such as vanillin, p-anisaldehyde and furfural, which have been chemically modified, including the insertion of nitrogen nucleophiles, can be used. The advantage of using an ionic liquid is, in addition to the ease of using another product in the process of the invention, the ability to use such a product once again, including the washing and removal of all organic compounds (2) and the extraction of the washing and washing of all lignin.

Any enzyme, or any mixture of enzymes, called cocktail of enzymes , any biological organism, such as any bacteria, microbe or fungus, which may facilitate the degradation of lignin in the material and thus lead to partial delignification of this material is also suitable for use in the context of the invention.

Enzymes, bacteria, microbes or fungi are usually carried by a fluid, which is most often a liquid, and more generally a solution.This carrier fluid can itself be carried by another fluid, which has different characteristics, the whole thus forming most often a complex, miscible, micellaire or biphasic system.

The enzyme can be a laccase, peroxidase, lignase or ATPase. ATPases include copper-exporting P-type ATPase A (copA). Peroxidases include dye-decolorizing peroxidases including type B (Dyp-B type), type P (Dyp-P type) and type 2 (Dyp-2 type).

Such enzymes can be secreted by a cultured fungus such as white-rot fungi .

The role of enzymes can be twofold: the partial delegnation is assisted if the enzymatic action is that of the organic washing fluid, and completed if the enzymatic action accompanies the action of the organic washing fluid by reducing the dissolved solvated elements from the lignin of the ligno-cellulosic material into elements of lower molecular weight.

At least one fungus can also be used, in which case it is noted that the fungal germs are active over time and develop mycelium filaments within plant cells.

Another preferred method of carrying out the soaking step (1) is to use at least one supercritical fluid, most often in mixtures.

The supercritical state is a state in which the contact angle of the compound with a substrate is zero, which implies that the compound completely wetens its substrate: thus, the supercritical fluid helps the ligno-cellulosic material to be filled with the other compound or compounds of the soaking stage (2) with which it forms a complex system.

The supercritical fluid may be chosen from carbon dioxide, water, alkenes of low molecular weight (i.e. at least 1 and strictly less than 5 carbon atoms) such as ethylene or propylene, alkanes of low molecular weight (i.e. at least 1 and strictly less than 5 carbon atoms) such as methane, ethane, propane, and their mixtures; alcohols of low molecular weight (i.e. at least 1 and strictly less than 5 carbon atoms) such as methanol or methanol, acrylonitrile, ammonium chloride, chloropropane, nitrous oxide, trichloroform, and their mixtures.

The supercritical state of carbon dioxide can be reached under relatively mild conditions, i.e. above 31°C and 7.4 MPa (74 bars). Supercritical conditions are more difficult to achieve for water (above 374.3°C and 22.1 MPa, or 221 bars): water can also be used in a more accessible state, close to the supercritical state, called sub-critical, which is also preferred.

The fluid of the soak (1) may also be chosen from: an aqueous solution containing a mixture of sodium chloride and sodium hydroxide, or an aqueous liquid containing monoethanolamine, or a basic solution containing KOH (for alkaline delignification); an aqueous solution containing a mixture of acetic acid and hydrogen peroxide, or an acid solution containing HBr, H2SO4 or H3PO4 (for acid delignification); a fluid containing at least one enzyme, possibly in the presence of at least one ionic liquid or in the presence of at least one ionic liquid and at least one sol (for enzymatic delignification) with an ionizing liquid usually derived from vegetable matter (for delignification); a liquid containing at least one ionizing liquid, or a liquid (assisted by at least one enzyme) with an ionizing solvent; a liquid (assisted by at least one ionizing solvent) containing ionizing solvent;such as ethanol (for organosolv-type delignification assisted by ionic liquid; in this case the ionic liquid may be minor in relation to the other or other solvent (s) in the mixture); an ionic liquid in mixture with at least one miscible solvent containing one or more enzymes in solution; a biphasic system, one phase of which consists of an ionic liquid, pure or mixed with at least one miscible solvent, such as ethanol, and the other phase consists of a supercritical fluid, such as CO2 (for delignification by ionic liquid assisted by supercritical fluid) or a biphasic system,where one phase consists of a pure ionic liquid or a mixture with at least one miscible solvent and the other phase consists of a supercritical fluid, containing in addition one or more enzymes in solution in the ionic liquid phase (for delignification by supercritical fluid assisted by pure ionic liquid or a mixture and assisted/complemented by enzymatic action);

The first compound of each element in the above list is usually present in the majority, i.e. at least 50% by weight.

According to a particularly preferred embodiment, the soak-step fluid (1) is a de-lignification fluid which additionally includes at least one polarising agent selected from the group consisting of ethanol, ethylene glycol, methyl ether, N-methyl pyrrolidone, dioxanes, dimethylformamide, diethylene glycol, diethylene glycol dimethyl ether, pyridine, n-butylamine, piperidine, morpholine, 4-picoline, 2-picthyoline, aniline, acetone, methanol, and their non-mixtures, as well as at least one surfactant in the selected group such as diethylammonium ions, diethylammonium and their diethylammonium anions, and possibly at least one surfactant in the group consisting of diethylammonium ions, diethylammonium ions, diethylammonium ions, diethylammonium ions, and their non-methionine and diethylammonium anions.

The presence of such a polarising agent makes it advantageous for the filler compound to penetrate more deeply into the lignin and cellulose structure of the material during the subsequent filler step (3).

The surfactant is generally chosen from anionic surfactants such as those based on sulphate, sulfonate, carboxylate or phosphate esters; cationic surfactants such as quaternary ammonium salts; non-ionic surfactants such as surfactants based on polyethylene oxide and/or polypropylene oxide, such as the commercial product family Pluronic® and Tween®, or chain-based such as the commercial fatty product family Span® and sugar; and zwitterionic surfactants such as amine oxides, such as sulphur dioxide, beta-aniline, alkylbethaine, amine deoxide, sulphofenine and their derivatives, such as sulphur melanin, can also be used.

Finally, the soaking fluid may include at least one N-oxyl catalyst such as tetrapropylammonium terrutenate (TPAP), 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), or N-oxyl 2-azaadamantane (AZADO) and their derivatives.

For example, the soaking step (1) may be carried out under vacuum, for example, with an aqueous organic solution containing 5 to 10% sodium chloride and 0,01 to 0,5% sodium hydroxide, at 50 to 90 °C for 2 to 10 hours, for example at 70 °C for 5 hours.

Washing stage (2)

The washing step (2) allows the extraction of lignin and other possibly dissolved compounds present in the ligno-cellulosic material as a result of the soaking step (1). The lignin will be present in the soaking fluid at the end of the step (2), most often in the form of fragments. In addition to the molecules from the lignin breakdown, breakdown products of other components of the ligno-cellulosic material may be found in the organic fluid of the washing step (2), such as molecules from the breakdown of the amorphous parts of the cellulose, simple sugars from the peripheral hemicellulose, i.e. certain extractable phases.

For example, if the extraction is carried out by means of successive washing sub-steps with a liquid organic fluid, the extraction is carried out until an organic washing fluid is obtained which is substantially free of lignin and other dissolved compounds. The physico-chemical parameters, such as temperature and/or pH, of the organic fluid used can be adjusted from one washing sub-step to another. Similarly, if the organic fluid in the washing step (2) is a mixture of compounds, the respective amounts of these compounds can be adjusted from one washing sub-step to another.

During the washing step (2), the residues of delignification are more easily extracted from the wood pores by agitation of the organic fluid of the washing step (2), or by mechanical or wave action, such as sonic.

The dissolved lignin which is extracted from the structure of the ligno-cellulosic material plays an essential role in the process of the invention.As explained above, other compounds can be dissolved and extracted, or even simply extracted, from the ligno-cellulosic material during the soaking (1) and washing (2) steps.

The organic fluid of the washing step (2) is preferably an organic fluid which may be any of the fluids mentioned in step (1) above; however, the preferred organic fluid is a liquid chosen from the group consisting of acetone, water, ethanol, hexane, heptane, isopropanol and toluene and their mixtures, and even more preferably from the group consisting of ethanol, hexane, isopropanol, heptane and their cellulose.

For example, the washing step (2) can be performed in a vacuum using an ethanol bath at 60°C for 4 hours.

The advantage is that the organic fluid can be recycled after use during the washing phase (2).

According to the process of the invention, the dissolved lignin recovered from the organic fluid of the washing step (2) is preferably used in a process of lignin recovery, usually at an industrial level, for the manufacture of a building material or a material used in aeronautics or a packaging material or a biofuel or a pharmaceutical compound or a chemical process. This can be used for the production of carbon fiber (by aromatic combination), fibreglass concrete, packaging, biocarburants (paranisation), pharmaceuticals, and chemical components (including ferrous acid) and high value (confusion), but also for various applications such as the extraction of aromatic compounds (such as sulfur dioxide), the production of green paper, etc. This process can also be used in the production of various types of chemical compounds (such as sulfur dioxide, sulfur dioxide, etc.).

The invention thus makes it possible, as has been envisaged in the literature, to make use of lignin thus extracted from the organic fluid of the washing step (2) in such varied fields as: biorefining (products of combustion, synthetic gas, bioethanol); specialty products of biological chemicals (aromatic derivatives such as vanillin, benzene, xylene, DMBQ (2,6-dimethoxy-1,4-benzoquinone), syringaldehyde, syringol, vanillic acid, sinapinic acid, p-hydroxybenzaldehyde, 3-ethylphenol, 2-methylphenol, 3-methylchol, 3-methoxycatheate; ferulic acid; typical gas such as carbon dioxide, carbon monoxide, methane or methanol); various specialty compounds (carbon fiber of low or medium grade, such as rubber compounds for aerosols, automobiles, motorcycles, wind turbines; polymers; additives for fishery products; additives for foodstuffs and animal products; additives for lubricants and other food additives; additives for plastics and other products; additives for animal welfare; additives for products such as paints, paints, varnishes, etc.);

Similarly, extracted compounds other than lignin are preferably used in a recovery process, such as a recovery process for sugars or aromatic or functional molecules, usually at an industrial level.

The following shall be used:

The filling step (3) is a step in which the filling (i.e. the action of penetrating the partially delignified structure) of the partially delignified structure by the filling compound is carried out. It can be carried out in one or more times. The filling compound must most often have the property of binding to the fibres of the ligno-cellulosic material still present within the structure, by chemical or physico-chemical anchoring.

Various techniques are possible for this filling, as is known to the professional. Generally, these techniques are series type (replacement of one fluid by another fluid in a step-wise series, repeated several times, successive impregnations, the concentrations of each fluid in the filling compound increasing incrementally, such as exponentially), by impregnation, by injection (by vacuum type RTM or RTM Light Transfer Tool for Resin Transfer Molding), by infusion (RIFT for Resin Infusion under Flexible Molding), vacuum or pressure, in a reactor or autoclave or vacuum furnace, or any other device that the professional knows how to perform this step.

The development of the conditions for filling the form is within the reach of the professional.

In the preferred case of the invention of the use of an autoclave, it may be recommended to alternate vacuum phases with pressurized phases to impregnate the ligno-cellulosic material well, as this alternation advantageously forces the filling compound to penetrate the material by the pressure difference thus created.

In one example, the filling step (3) involves a pressure impregnation step of the structure partially de-lignified by a solution containing the filling compound.

The filling step (3) may also be carried out in an oxygen-free atmosphere, either under vacuum or in the presence of diazote, for a period of, for example, a few minutes to 24 hours and preferably 20 to 24 hours per 500 mL volume of filling compound, the volume being appropriate to ensure the filling of the structure taking into account the removal of oxygen from the cavities of the wood-cellulosic material and the possible production of the filling compound in the event of under vacuum and/or heating.

The filling step (3) of the treatment process of the invention can be carried out essentially in two modes of execution, which can be adapted according to the ligno-cellulosic material used.

In a first embodiment, the filler compound is a polymer or copolymer, whether or not formulated.

In this case, the polymer or copolymer is usually in the liquid state at the pressure and temperature conditions of the filling step (3), to achieve the filling step (3) by dipping the partially de-lignified structure in the liquid polymer or copolymer.

Preferably the polymer or co-polymer is thermoplastic, and the temperature of the filling step (3) is higher than its glass transition temperature. In this case, the finishing step (4) consists of a resting at a temperature below the glass transition temperature of the polymer or co-polymer. This assumes that the polymer or co-polymer generally has a glass transition temperature higher than the subsequent temperature of use, typically above about 25°C (ambient temperature).

The polymer or copolymer is preferably chosen from the group consisting of polyacrylates, polyamides (such as DuPont Nylons®), polyesters, fluoropolymers (such as DuPont Teflon®), polyethylene, polypropylene, polybutene, polystyrene, polyphenylene oxide, polyvinyl chloride, polyvinylidene chloride, polycarbonate, polylactic acid), polyestersulfones, polyesters, polyesters, and from the group consisting of the polymers and copolymers listed above, non-aluminium and obtained from the secondary production of the latter.

Cellulose, starch, polypeptides, proteins and polymers derived from these compounds, such as cellulose acetate or starch acetate, whether or not formulated, may be used in this mode of use.

In a second embodiment, the filling step (3) is a polymerizable monomer present in a monomeric solution or in a monomeric formulation at the filling step pressure and temperature conditions (3). Preferably the filling step (3) is a polymerizable monomer present in a monomeric solution at the filling step pressure and temperature conditions (3), the monomeric solution also including at least one catalyst. Such a polymerizable monomer generally leads to a thermoplastic (polymer) or a thermosetting (moderate) polymer.

Filler compounds may include monomers, in the form of monomeric solutions or even monomeric formulations.

In general, it is recommended to avoid using a filler compound that may generate volatile and/or unstructured by-products from the composite material.

A monomeric solution is a mixture of one or more monomers, with or without an agent that activates the polymerization of these monomers. A monomeric solution is a monomeric solution containing at least one additional compound. Such an additional compound is usually chosen from among oligomers, polymers, copolymers in respect of thermoplastics, or pre-polymers and pre-co-polymers accompanied by at least one hardener for thermodynamic materials. This additional compound may also be at least one agent that allows polymerization such as an initiator (e.g. a biochemical initiator such as ossipepyrine, acycloride, amine, carboxylic acids and their mixtures), a catalyst, a heat-degradable or a radiation-activated or a heat-transfer-inhibiting agent, or a mixture of these compounds, or a catalyst, or a heat-degradable or a radiation-retardant, or a charge, or a charge.

The mineral charge is usually chosen from the group formed by alumines, clays, carbon powders, glass beads, diamonds, gypsum, limestone, mica, perlite, quartz, sand, talc, silica, titanium and their mixtures, preferably chosen from the group formed by clays, diamonds, glass beads, gypsum, limestone, mica, perlite, quartz, sand, talc and their mixtures. The mineral charge can be mineralized to increase its dispersion and stability in the monomeric filling formulation. At least one tensioactive function can also be added for this purpose.

The catalyst is chosen so that it preferably catalyzes a radical polymerization reaction, which generally depends, as is known to the professional, on the monomer, the polymerization mode and its control.

The catalyst is preferably chosen from the group formed by azo-type compounds of formula R-N=N-R' where R and R' are alkyl groups possibly including at least one additional function, such as azoisobutyranonitrile, peroxides, alkyl compounds (usually comprising 1 to 6 carbon atoms per molecule) halogenated (i.e. comprising one halogen atom which is chlorine, bromine, iodide or fluorine), nitroxyl diethylates, tert-terthyl carbonyl tert-terthyl compounds. However, any other known catalyst of tert-terthyl tert-terthyl is also possible, such as peroxyabutyl peroxyabutyl peroxide, peroxyabutyl peroxyabutyl peroxyabutyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl peroxyl perox

Depending on the method of manufacture, the monomeric solution or monomeric formulation of the filling step (3) may also contain at least one plasticizing agent, which may be any solvent, oligomer or charge, to reduce the viscosity of the filling compound and thus allow a better penetration of the filling compound into the ligno-cellulosic structure of the material.

If the plasticizing agent is a solvent, it is generally chosen so that it largely evaporates at room temperature in order to limit the emission of volatile organic compound during the lifetime of the composite material structure. Indeed, the use of monomeric solution or monomeric formulation containing a low volatile solvent is not preferred in the present invention as the impregnation of a solvent into the structure of the ligno-cellulosic material may lead to the creation of ungrafted molecules trapped in the composite material structure which could be gradually re-charged. If the agent is an oligomeric, the latter is chosen in such a way that it anchors itself abruptly to the structure in order to avoid any further enlargement.

At least one structure preserving agent of the final composite material, such as a UV absorber, may also be added to the monomeric filling formulation to improve its structure holding. Such an agent may be selected from chromophore compounds such as anthraquinone, benzophenone or benzotriazole pattern compounds, diphenyl acrylate, and all or part of the compounds extracted during one of the soaking (1) or washing (2) steps, and their mixtures.

At least one flame retardant, fungicide, bactericidal or insecticidal compound may also be added to enhance the properties of the final composite material structure.Flame retardant compounds include aluminium trihydrate, antimony trioxide, antimony pentoxide and oragnosphosphate compounds, and all or some of the compounds extracted during the soaking (1) or washing (2) phase, and mixtures thereof.

Depending on the method of manufacture, the monomeric filling formulation shall also include at least one polarising agent selected from the group consisting of ethanol, ethylene glycol, methyl ether, N-methyl pyrrolidone, dioxans, dimethylformamide, diethylene glycol, diethylene glycol dimethyl ether, pyridine, n-butylamine, piperidine, morpholine, 4-picoline, 2-picoline, dilamine, aniline, acetone and methanol.

The presence of such a polarising agent is advantageous for better penetration of the filling compound into the ligno-cellulosic structure.

The monomer is preferably chosen from petroleum-derived (so-called petroleum-derived) monomers, including methacrylates such as ethyl methacrylate, methyl methacrylate, propyl methacrylate, butyl methacrylate, hexyl methacrylate, octyl methacrylate, octyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate; acrylates such as vinyl acrylate; polyethylene methacrylates such as vinyl vinyl diethyl methacrylate, where vinyl vinyl diethyl vinyl diethyl vinyl diethyl vinyl diethyl vinyl diethyl vinyl diethyl vinyl diethyl vinyl diethyl vinyl diethyl vinyl diethyl vinyl diethyl vinyl diethyl vinyl diethyl vinyl diethyl vinyl diethyl vinyl diethyl vinyl diethyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl vinyl

Other monomers that lead to the formation of thermosetting polymers include petroleum-derived compounds such as thermosetting resin precursors such as epoxy resin precursors, epoxy prepolymers derived from bisphenol such as bisphenol A diglycidyl ether (BADGE), or any epoxy bisphenol, as well as glycidyl methacrylate or glycidyl allyl ether, precursors of oxetane residues, precursors of phenolic residues, precursors of uric acid residues, residues of cyclic compounds; and in general, such a mixture of iodine or ammonium iodide. In this case, at least one of the hardest known iodide resins is a carboxylic acid, which can be a solid or solid solution of anhydrous or of any other solid.

Biosourced monomers leading to the formation of thermoplastic or thermosetting polymers, identical or different from petroleum monomers, are also included, including tannins such as flavan-3-ol (afzelechin, gallocatechin, catechin) and terpenes; resveratrol; resorcinol; glycerol and glycerol derivatives such as epiclorhydrin, isomers of propanediol and glycolic acid; derivatives of sucrose (orbide, sorbitol pollycidyl ether, trehalose, D-glyceraldehyde, D-reoxytheroxide, D-throse, D-throsine, D-betacarbins, D-carbins, D-glucans, D-furans); derivatives of acetic acid and fume (derivatives of acetic acid or isomers of isomers of fume); and derivatives of acetic acid (derivatives of fume, D-carbins, D-carbins, D-carbins, D-carbins, D-carbins, D-carbins, D-carbins); and derivatives of acetic acid (derivatives of acetic acid or isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of isomers of(i) hydroxycyanuric acids, such as those derived from formic, lactic and secic acids; bioethylene (or biological ethylene) bioethylene; glycol (or biological ethylene glycol) biopropylene (or biological propylene); bio-1,4-diethyl methanol (or biological butanediol); melanin derivatives, such as tertiary acids, triglycerides, vanadiol, vanadiol and vanadiol; vanadiol and vanadiol; their derivatives; vanadiol and vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vanadiol; vansuch as monomers from a combination of sugar and body fat derivatives.

Biosourced means a molecule in which all or part of the constituent atoms are derived from a resource derived from biomass, and which is not the result of anthropogenic transformation of a fossil resource.

Finally, hybrid biobased monomers lead to the formation of thermoplastic or thermosetting polymers, identical to biobased monomers.

derived from X means, in the present invention, a compound synthesized from compound X by a short sequence of chemical reactions essentially retaining the identity (i.e. the main chemical structure) of compound X, such as the addition of a function or an increase in the length of the carbon chain (i.e. an addition of a carbon chain) or an oxidation or reduction or nucleophilic substitution or a cycle opening.

Even more preferably, the monomer solution or monomer formulation, preferably the monomer solution, preferably contains at least one monomer selected from: petroleum monomers including methacrylates such as butyl methacrylate, methyl methacrylate, ethyl methacrylate, glycidyl methacrylate, tri-n-butyl tin methacrylate; phthalates such as dialkylphthalates; nitriles such as acrylonitrile; styrene and styrene derivatives such as t-butyl styrene and chorostyrene; vinyl compounds such as vinyl acetate, vinyl chloride and vinyl hydrate; ethylene properties such as ethylene glycol or ethylene oxide butyrene; monophosphoric compounds; and biochlorinated terpenoids; including terpenoids and terpenoids obtained after reaction with at least one glycol glycol;isomers of propanediol and glycolic acid; derivatives of sugars; derivatives of furfural (generally from the acid depolymerisation of hemicelluloses); derivatives of lactic and formic acids; monomers of castor oil such as sebatic acid; hydroxyalkanoic acids such as those of formic, lactic and sebatic acids; bioethylene (or biological ethylene); bioethylene glycol (or biological ethylene) bio-propylene (or biological propylene) bio-1,4-butanol (t-1,4-butanol); 1,4-diethylenediol; biological acids such as t-butylene and their ligands.

Any mixture of the above compounds is also preferred according to the invention.

The advantage of using bio-based monomers is that they can either be recovered later in the recycling of the end-of-life composite material or facilitate the destruction of the end-of-life composite material, thus producing a partially or fully recyclable composite material, which gives the process of the invention the character of a sustainable or even ecological process (or green process).

One method of manufacture is to make the filling compound from two monomers which lead to the manufacture of a thermosetting polymer in the finishing step (4), which consists of polymerization and cross-linking.

An example of a second embodiment is that the filling step (3) involves a diffusion step involving a first sub-step of immersion of the partially delignified structure in a mixture of 50% monomeric solution and 50% solvent, e.g. ethanol, then a second sub-step of immersion of the structure from the first sub-step in a mixture of 75% monomeric solution and 25% solvent, e.g. ethanol, then a third sub-step of immersion of the structure from the second step in a 100% monomeric solution, then a fourth sub-step of immersion of the structure from the third sub-step in a 100% monomeric solution mixture and a catalysis step, being carried out every 24 hours at room temperature, e.g. for a few hours.

Depending on the method of manufacture, the filling step (3) can be carried out advantageously in the presence of a neutral gas such as diazo­terone or argon under pressure or a supercritical (i.e. supercritical) compound.

The catalyst is as described above.

The neutral gas is an advantageous means of preventing the evaporation of the filling compound during the filling (3) and finishing (4) stages and of preventing its contact with the ambient air, and in particular with the oxygen in the air.

Depending on one embodiment, the monomer is such that when polymerized it has substantially the same optical density as cellulose. The refractive index of the polymer thus obtained is typically in the range of 1.35 to 1.70, more precisely between 1.44 and 1.65, and even more precisely between 1.52 and 1.60, and is often taken to be around 1.47, 1.53, 1.56 or 1.59, with a possible variation around these values of the order of 10%.

Finishing stage (4)

The finishing step (4) is a step in which the filling compound of the partially delignified structure filled from the filling step (3) is fixed in the structure, which results in a composite material structure formed from a three-dimensional network of processed filling compound incorporated into a network of cellulose and lignin.

It is carried out in different ways, depending in particular on the method of carrying out the filling step (3).

This finishing step (4) is therefore a fixation step of the filler compound, preferably by polymerization and/or cross-linking where the filler compound contains at least one monomer, often in the form of a filler solution or formulation.

As explained earlier, the term anchoring refers to the creation of molecular bonds. Structuring polymer chains within the ligno-cellulosic material architecture is done either by covalent bonds, in which case a chemically cross-linked network is obtained, or by weak bonds or interactions, such as van der Waals hydrogen bonds, in which case a physical network is obtained, or by a mixture of the two types of bonds.

The filler compound thus forms a polymer which may thus belong to the family of thermoplastic polymers or thermosetting polymers. Such polymers may be chosen from the group formed by acrylic resins, aminoplast resins, diallyl phthalate resins, epoxy resins such as Spurr epoxy resins (such as the commercial product EM300 sold by Sigma-Aldrich), melanin resins, methacrylic resins, oxetane resins, phenolic resins, polyacetal resins, polyesters modified, polycarbonate and aliphatic aromatic resins, silicon and silicon aromatic polyesters, polysorphine or polyphenol resins, or their combinations, such as organically modified polymers, polymers and organically modified polymers, organically modified polymers and organically modified polymers, silicones and their residues, or organically modified polymers and organically modified polymers and polymers (such as polymers, silicones, silicones, silicones, silicones, silicones, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polymers, polys, polys, polys, polys, polys, polys, polys, polys, polys, polys, polys,

The anchoring of the filling compound is carried out in different ways, in particular depending on the method of completion of the filling step (3).

Thus, when the filling step (3) is performed in the first embodiment, i.e. the filling compound is a polymer or co-polymer of thermoplastic preference, the finishing step (4) consists of freezing (or fixing) as far as possible the polymer or co-polymer within the structure for further use. In other words, the finishing step (4) consists of putting the said polymer or co-polymer in a physical state such that it cannot practically leave the structure under the temperature and pressure conditions considered. These pressure and transition conditions depend essentially on the further use of the polymer or co-polymer material, typically whether it is intended for use in a general temperature or in a climate (i.e. if it is to be placed in a temperature or in a transition temperature) or in which the polymer or co-polymer is to be used in the structure.

Thus, when the filling step (3) is carried out in the second embodiment, i.e. the filling compound is a polymerizable monomer present in a monomeric solution, the finishing step (4) consists of polymerizing the monomer in the presence of the catalyst. This is usually done by any possible polymerization technique, such as the thermal pathway, the UV pathway, or the plasma technique.

For example, the monomeric solution contains butyl methacrylate and styrene in the ratio of one part butyl methacrylate to 3 parts styrene, and the catalyst present in the finishing step (4) is azoisobutyronitrile in the ratio of 0.05 parts. In this case, the finishing step (4) can be carried out by heating at 15°C to 80°C, e.g. 40°C, under vacuum or oxygen-free atmosphere, e.g. oxygen-free atmosphere, for 20 to 50 hours, e.g. for about 24 hours.

When the polymer or copolymer is thermosetting, the filling step (3) has been carried out in the liquid state and at a temperature above the temperature range at which cross-linking takes place and the polymer or copolymer begins to harden, and the finishing step (4) consists of polymerisation and then cross-linking of the source monomers of the thermosetting polymer at a temperature below the said temperature range of the polymer or copolymer.

It is therefore possible to fill (3) the ligno-cellulosic material and to initiate the induced precipitation (4) of the filling compound into it almost simultaneously.

Optional post-treatment steps (5) and/or (6)

Depending on the invention, the treatment process may also include a pressurization step (5) of the structure from the finishing step (4). The pressurization step (5) is typically performed at 80 to 250°C for 5 to 30 minutes at a pressure of 0.1 to 2.0 MPa.

This pressing step (5) may be followed by a surface finishing (or surface treatment) (6) step of the structure resulting from the pressing step (5).The surface finishing step (6) can typically be carried out chemically, e.g. by means of ethyl acetate, or by thermal means and accompanied by pressing, in which case the pressing (5) and surface finishing (6) steps are carried out simultaneously.

The surface finishing step (6) can also be carried out without a step (5) being carried out in advance, in which case it can be carried out by steam treatment with acetone steam or methanol chloride.

The structure

The composite material structure according to the second aspect of the invention is generally advantageously a structure of good fire resistance, which is increased compared to the ligno-cellulosic material before treatment (by its increased bulk mass and by the absence of air - and therefore oxygen - in its densified cell structure), imputrescible (by the absence of air in its densified cell structure which can therefore no longer interact with ambient moisture), of improved durability compared to the ligno-cellulosic material before treatment, and which has improved mechanical characteristics of compressive and bending resistance compared to the native ligno-cellulosic material before treatment.

According to a preferred mode of relation, the composite material structure has a largely or almost entirely homogeneous or periodic refractive index, depending on the nature of the native ligno-cellulosic material. According to one mode of realization, the composite ligno-cellulosic material structure is significantly transparent. But it can also be opaque. Preferably, the composite ligno-cellulosic material structure is significantly translucent.

transparent means the ability of a visually homogeneous body to let through at least 90% of the incident light. This measurement is made in relation to the direct light transmission for a given ambient lighting by comparing the value (in lux) of the ambient lighting and the value (in lux) of the light transmission flux obtained after passing through the structure.

translucent the ability of a body to let in between 5% and 90% of the incident light. A translucent body may not appear homogeneous. In the present invention, some less delineated areas of the ligno-cellulosic material room may absorb incident light rays according to the structure of the native ligno-cellulosic material; the more delineated areas will tend to appear lighter and let light through more easily than the less delineated areas.

A native ligno-cellulosic material structure is generally an opaque material in its common use dimensions. If the thickness of this structure is reduced to less than 500μm, the native ligno-cellulosic material is then in the form of a brittle, flexible sheet, can let through incident radiation, is translucent, despite no treatment, but the material does not have the other properties of the final composite material.

This optical property is advantageously obtained by homogenization of the optical index of the processed filling compound with that of the cellulose (especially alpha cellulose) revealed within the structure of the ligno-cellulosic material by the filling step (3) and by creating a material continuum during the finishing step (4). This provides the structure with additional optical quality, as all or part of an incident radiation can be transmitted through this composite material structure by homogenization of optical density.

The continuity of optical indices is generally not perfect from a certain volume of ligno-cellulosic structure. Depending on the native ligno-cellulosic material and the rate of delignification, the extraction of lignin from the ligno-cellulosic material may not be uniform in the planes of its faces and depth, so that delignification and, consequently, optical rendering do not appear homogeneous.It is therefore possible for some woods, especially those with annual growth rings (summer and spring alternation), that one of the parts, often summer wood, is less prone to be treated by the soaking (1) or washing (2) steps, thus leaving more or less translucent or transparent or even opaque areas after treatment by the (3) and (4) steps.The optical property is generally observed on the composite material structure.

Typically, the composite material structure has at least a dimension of at least 2 mm and not more than 40 cm. These 40 cm may correspond to the total thickness of a CLT panel. This may not strictly correspond to the dimensions of the pre-treatment structure according to the invention process. Dimensional changes may result from the process of changing the structure of the ligno-cellulosic material during steps (1) and (2), leading for example to deformation (slight torsion) or a decrease in the size of the composite material compared to the ligno-cellulosic material without pre-treatment, with or without a preferred deformation axis.

The structure of the composite material often has a higher density than that of the native ligno-cellulosic material, for example 5% to 1000% higher or even 10 to 200% higher, depending in particular on the ligno-cellulosic material, the degreasing rate and the nature of the filling compound.

The composite material structure obtained by the invention process is preferably a finishing element, a secondary work element or a primary work element.

As a reminder, there are three types of wood cuts: The test shall be carried out on the test vessel in accordance with the requirements of paragraphs 6.2.3 and 6.2.4.

The applicant has treated all possible cutting types, although the following examples only cover CT and CLR cuts in the samples.

It should be noted that according to the invention, the preferred cross-sections and longitudinal sections generally react similarly to the process.

The tradesman is in a position to determine which cutting tool should be preferred for the treatment according to the invention: for example, for structural applications taking advantage of improved mechanical properties, the CLR cutting tool will be preferred while for applications taking advantage of new optical properties, the CT cutting tool will be preferred.

Room

The room according to the third aspect of the invention may be used in a wide variety of outdoor uses, in which case the room is generally chosen from soffits, window frames, doors and door frames, porches, bank planks, garden shelters, terraces (such as exterior flooring and exterior pavements) and timber framed buildings (or wood siding), urban developments and the like. Alternatively, the room may be used in a wide variety of indoor uses, in which case the room is usually chosen from packaging elements for luxury, design elements (or design), furniture items (such as sports tables and menus for food items such as voices, skates, yachts, furniture or interior items such as furniture, furniture or building elements (such as furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture, furniture,

The figures

The invention will be better understood by reference to the attached drawings on which: Figure 1 shows the principle of the process according to the invention; Figure 2 shows a partial implementation of a process step according to the invention, involving the immersion of the structure of the ligno-cellulosic material in a liquid; Figure 3 shows an example of the application of the pressurization step according to the invention; Figure 4 shows a complete implementation of the filling (3) and finishing (4) steps according to the invention.where these steps involve the immersion of the structure of the wood-cellulosic material in a liquid as shown in Figure 2; Figure 5 schematically represents a scanning electron microscope (SEM) view of a longitudinal cut of wood in the natural state; Figure 6 schematically represents a three-dimensional macroscopic view of a wood structure in the natural state (or native) before treatment as per the invention; Figure 7 schematically represents a three-dimensional microscopic view of the structure of wood in the natural state (or native) before treatment as per the invention; Figure 6 schematically represents an intermediate scale view of the structure,After the steps of soaking (1) and washing (2) as described in the invention in Figures 9 and 10;Figure 9 schematically represents a three-dimensional macroscopic view of the wood structure in Figures 6 and 7 after the steps of soaking (1) and washing (2) as described in the invention;Figure 10 schematically represents a three-dimensional microscopic view of the wood structure in Figure 9;Figure 11 schematically represents a three-dimensional macroscopic view of the wood structure in Figures 9 and 10 after the step of filling with a wood filling compound;Figure 12 schematically represents a three-dimensional macroscopic view of the wood structure in Figure 11 after Figure 13;Figure 12 schematically represents a three-dimensional microscopic view of the structure in Figure 11 after the end of the wood structure in Figure 12 (4),i.e. the composite wood structure obtained by the treatment process according to the invention; Figure 14 schematically represents a microscopic three-dimensional view of the composite wood cutting of Figure 13; Figure 15 shows three scanning electron microscope (SEM) photographs at a semi-microscopic scale of a part of the fir structure at different stages of the treatment process according to the invention, i.e. from left to right respectively before de-lignification treatment, after de-lignification and before impregnation with a monomer compound, and after polymerization of the impregnated monomer compound; Figure 16 shows two part-scan electron microscope (SEM) photographs after enlargement of the structure of the sapin of Figure 15,i.e. on a microscopic scale, i.e. from left to right before treatment and after polymerisation of the impregnated monomer compound;Figure 17 shows the principle diagram for measuring the bending of a wood structure treated by a process according to the invention;Figure 18 shows the result of measuring the bending of a fir structure before and after treatment;Figure 19 shows the principle diagram for measuring the axial compression of a wood structure treated by a process according to the invention;Figure 20 shows the result of measuring the axial compression of a sapin structure,Before and after treatment; Figure 21 shows the principle diagram of the measurement of the axial tensile strength of a wood structure treated by a process according to the invention; Figure 22 shows the result of the measurement of the axial tensile strength of a fir structure before and after treatment; and Figure 23 shows ten photographs taken with the Zeiss LSM710 Upright microscope after treatment of six different wood species.

Figure 1 shows the treatment process according to the invention in a schematic sequence of steps, each represented by a box, each corresponding to the step bearing the same reference number of the process according to the invention, it being understood that references (5) and (6) are optional steps as shown by the dotted arrows connecting boxes 4, 5 and 6.

The first step (1) is a soaking of the ligno-cellulosic material structure, followed by a second step (2) which is a washing of the structure from the step (1) to remove the dissolved lignin from the step (1), followed by a third step (3) of filling the partially de-lignified structure from the washing step (2) with at least one filling compound. The last and fourth steps (4) are a transformation of the filling compound from the third step (3) to the filling structure from the third step (4) This may be followed by a final filling of the structure from the same layer of the structure (5), followed by a third step (5) which may be incorporated into the structure from the third step (4) and then a net-like structure from the same layer of the structure (5), which may be filled with a net of matrix material from the third step.

Figure 2 shows a schematic example of a partial implementation of a treatment step of the inventive process involving the immersion of a structure of ligno-cellulosic material (10) in a liquid. The structure of ligno-cellulosic material shown is a structure of wood, e.g. fir. It is immersed in a treatment solution (11), which may be an organic solution of the soaking step (1), an organic solution of the washing step (2) or a solution containing at least one filling compound of the filling step (3). The whole is supported by a support (15), e.g. teflon, which is itself fixed in a tank (12), e.g. stainless steel.

Figure 3 shows a schematic example of the implementation of the optional pressurization step (5) of the invention process. In this case, the composite material structure (10') is compressed into a compression apparatus (13, 14) consisting of two symmetrical jaws (13) and (14) which can be brought together by taking the interlayer (10') into a clamp.

Figure 4 shows a schematic example of a complete implementation of the filling (3) and finishing (4) steps of the process of the invention, where these steps involve the immersion of the structure of the ligno-cellulosic material in a liquid as shown in Figure 2.

In this Figure, the assembly shown in Figure 2 is arranged within a chamber (25). Specifically, the tank (12) is fixed within the chamber (25) by means of a metal support (16). The chamber (25) is such that it allows the pressure and temperature conditions which are present within it to be controlled. These conditions depend mainly on the nature of the filling compound. The chamber (25) may be a vacuum furnace or an autoclave.

A pipe (22) divided into a pipe (22a) and a pipe (22b) allows, by means of the respective valves (17) and (18), respectively, to empty or introduce N2 diazote into the enclosure (25).

A pipe (23), which is divided into a pipe (23a), a pipe (23b), a pipe (23c) and a pipe (23d), allows, by means of the respective valves (19), (20), (21) and (26), to discharge or introduce into the enclosure a respective solution (24a), (24b), (24c) or (24d). A pure solution (24a), (24b), (24c) or (24d), or a possible mixture of at least two of these solutions (24a), (24b), (24c) and (24d), thus constitutes the treatment solution (11) (which may vary according to the step or sub-step of the process concerned), in which the wood structure is bathed (10). This allows, for the purpose of the filling step (3), to carry out a treatment of the structure in series (10), usually involving successive immersions in order of the solutions, for example, in two or more series, usually in series of 6 (3).

As an alternative to the device shown in Figure 4, another device may be provided with as many organic treatment solutions as necessary, each treatment solution being associated with a pipe on which a valve is located, connected to the pipe (23) in direct relation to the enclosure (25).

The micro-architecture of the wood is shown in Figure 5. The scale is a schematic view with scanning electron microscope (SEM) of a longitudinal cut of a wood structure, e.g. walnut, in its natural state. The scale distinguishes the cellulose cavities (or lumen ) (28) bounded by cellulose fiber walls (27) and the cross-sectional perforations forming pores or channels (29) between the cell cavities. These cell cavities have a cross-sectional dimension of about 30 to 60 μm for wood resin and 70 to 350 μm for wood schmuck. The cross-sectional perforations (29) represent areas represented for the resolution of the cellulose fibers (27) and the cross-sectional dimension of the structure, which varies from about 15 to about 30 μm. The cross-sectional perforations (29) represent areas represented for the resolution of the firewood or the circularly oriented structure of the firewood, and the cross-sectional dimension of the structure, shown in Figure 6.

Figures 6 and 7 show schematically two three-dimensional views, macroscopic and microscopic respectively, of a wood structure in its natural (or native) state, i.e. before treatment according to the invention. These cavities (28) are of medium size wood in the transverse direction of about 75 μm, with disparities according to the nature of the wood, i.e. about 30 to about 60 μm for resinous wood and about 70 to about 350 μm for firewood. These cavities (28) are bounded by walls of average thickness of about 2 to about 10 μm for resinous wood and firewood.

As shown in Figure 7, the micro-architecture of wood from which its mechanical strength in the natural state derives comes from the whole of the walls of the cell cavities (28) which are composed of tubes or microfibrils (45), which are themselves formed into bundles or macrofibrils (47). The macrofibrils (47) are linked by chemical bond to transverse support structures of hemicellulose (46), linked by transverse chemical bond to longitudinal support structures of lignin (44), this whole (46, 44) serving as support for the macrofibrils (47) of cellulose.

Figures 8, 9 and 10 show schematically three three-dimensional views, respectively at the intermediate scales between macroscopic and microscopic, macroscopic and microscopic, of a wooden structure after the steps of soaking (1) and washing (2) according to the invention.

The cell wall (49) is distinct, having thinned out from that shown in Figures 6 and 7. The thickness of the cell wall (49) is about 2 to about 10 μm, averaging about 6 μm. The microfibrils (45), hemicellulose (46) and macrofibrils (47) are substantially unchanged from Figures 6 and 7.

The cell wall (49) of cellulose comprises a middle lamella (61) about 0.2 to about 1 μm thick, and two walls, the primary wall (55) about 0.1 μm thick, and the secondary wall (60), itself made up of three sub-layers (52), (53) and (54) respectively in the direction of the cavity (28) outwards, the first sub-layer (52) being about 0.1 to 0.1 μm thick, the second sub-layer (53) about 0.5 to 0.5 μm thick, and the third sub-layer (54) about 0.1 μm thick. The perforation is also called a transverse perforation (59), which is also of medium size, about 0.02 to 0.6 μm thick, and is surrounded by a perforation of about 0.4 to 0.2 μm.

In the partial delignification carried out by the soaking (1) step combined with the washing (2) step, the primary wall (65) and the third sub-layer (54) of the adjacent secondary wall (60) were the most delignified, being themselves the layers or sub-layers most loaded with lignin, the third sub-layer (52) being itself very low in lignin, having been practically not delignified. This explains the differences in dimensional variations within the structure of the ligno-cellulosic material which occur during the partial delignification according to the invention.

It should be noted that Figure 8 could also illustrate, by adapting the dimensions shown above, the material before treatment during the treatment steps of the invention process, namely the soaking (1) and washing (2) stages, since during these stages the only change observed is due to the thickness of some of the layers and sub-layers as explained above, which decreases with the treatment.

Figures 11 and 12 show schematically two three-dimensional, macroscopic and microscopic views of the wood structure in Figures 9 and 10 after the filling step with a filling compound (3). These include the microfibrils (45), the lignin light structure (44'), the hemicellulose structure (46), the macrofibrils (47) and the cavity walls (49) (57). These cavities (57) are now filled with the filling compound, forming a three-dimensional filling network (58).

Figures 13 and 14 show schematically two three-dimensional, macroscopic and microscopic views of the wood structure in Figures 11 and 12 after the finishing stage (4) (generally consisting of polymerization) and thus schematically illustrate the composite wood structure obtained by the treatment process of the invention, including the microfibrils (45), the lignin lightweight structure (44'), the hemicellulose structure (46), the macrofibrils (47), and the walls (49) of the three-dimensional filling network (59).

Figures 15 to 23 are illustrated in the following examples.

The invention will be better understood by reference to the following examples of execution, with reference to the drawings annexed.

Examples

The following examples illustrate the invention without limiting its scope.

Example 1 - Treatment of a fir structure according to the invention

A parallel-epipedal sample of fir wood measuring 0.5 cm x 4 cm x 8.5 cm (IxLxh) was treated according to the method of the invention, which resulted in a composite specimen measuring 0.45 cm x 3.6 cm x 8.2 cm (IxLxh) in laboratory experiments.

The chamber used was a vacuum furnace (25).

Thus, the sample was treated during a first soaking step (1) by three identical successive sub-steps, each consisting of immersion of the sample in a 6 per cent sodium chloride and 0.05 per cent sodium hydroxide solution, under vacuum, at a constant temperature of 70 °C for 5 hours.

The sample washing step (2) was then carried out by immersing the sample from the previous soak step (1) in four identical first successive sub-steps, each consisting of immersing the sample from the previous step or sub-step in a 99% ethanol solution at 60 °C for 4 hours under vacuum, followed by three identical second successive sub-steps, each consisting of immersing the sample from the previous sub-step in a 99% hexane solution at 50 °C for 3 hours under vacuum.

The sample from the washing step (2) was then left to rest for 2 hours so that the hexane still present in the wood sample evaporated.

The filling (3) and finishing (4) of the resulting sample were carried out by means of the device shown in Figure 4.

The filling step (3) was carried out in the second method, by vacuum impregnation. Thus, a monomeric solution primary composed of one part butyl methacrylate and three parts styrene was obtained after purification of these compounds by means of a filter powder made of diatomite. The primary monomeric solution was mixed for a first batch, at a ratio of 50% by volume to 50% ethanol. The primary monomeric solution was mixed, at a ratio of 75% to 25% ethanol, for a second batch. The primary monomeric solution (at 100%) constituted the solution of the third batch. The primary monomeric solution (95%), at a ratio of 0.05 to 0.05 of catalyst (atriobutyrone), constituted the solution of the fourth batch.

The filling step (3) thus comprised four series, each series comprising four successive sub-stages, followed by subsequent solutions, made from solutions of the fourth series (monomer solution + catalyst) (24a), ethanol (24b), hexane (24c) and monomer solution (24d), without manipulation of the structure (10) and without contact with air.

At the end of the filling step (3), the solution (11) was drained by releasing the vacuum (17) and blowing diazote (18) to saturate the volume of the enclosure (25), which advantageously prevented the evaporation of the monomers present in the structure (10).

The next finishing step (4) was a polymerisation step of the butyl and styrene methacrylate monomers filling the sample at the end of the filling step (3). This polymerisation, leading to the formation of butyl-styrene methacrylate copolymer, was conducted under vacuum for 20 to 24 hours for 500 mL of monomeric solution (11) at 80°C for the first two hours and then 50°C for the rest of the step.

This finishing step (4) was followed by a pressurization step (5) which was carried out in the device in Figure 3. The sample from the finishing step (4) was wrapped between two latex sheets of 0.7 mm thickness each, the two sheets completely covering the sample and thus overlapping on the 4 edges. They thus created a pocket matching the shape of the sample. This pocket was then emptied by a valve, and the whole containing sub-content thus forming the structure (10). The wood was placed in a light oven at 40°C for 24 hours. The pressurization step (5) was followed by a step of moving the structure of the structure from the surface of the acrylate, thus obtaining a surface of acrylate (6) in the course of the process of casting.

The composite fir sample obtained was translucent.

A variant can also be envisaged where the enclosure (25) is an autoclave (25), in which case a single set may be sufficient to perform the filling step (3), the finishing step (4) is performed by immersion in a bath and the pressurization (5) and surface finishing (6) steps are not then necessary.

Example 1 was repeatedly performed to obtain several samples of composite fir which were evaluated in destructive mechanical and non-destructive optical tests, as explained in Example 2 below.

Example 2: Evaluation of the composite fir structure resulting from the treatment process of the invention and obtained in Example 1

The fir sample forming a composite fir structure obtained in example 1 was evaluated for both its mechanical strength and optical properties.

Mechanical tests as illustrated in Figures 17 to 22 Flexion measurement shown in Figures 17 and 18

This measurement was carried out on samples of fir of dimensions 0,7 cm x 2,5 cm x 10 cm (IxLxh) using a method developed by the applicant, consisting of three identical pulleys (39) of 3 cm diameter, which bend the structure, these three pulleys (39) being spaced two by two by 3,5 cm, the distance between the two most distant pulleys (39) being 7 cm.

Figure 17 shows the principle diagram for measuring the bending of the fir sample forming the composite fir structure (38) of the invention.

As shown in Figure 17, an increasing F-force was applied to the sample perpendicular to its main plane and the maximum stress just before rupture (f-arrow) was measured.

Figure 18 shows the result of this measurement of the bending of the fir sample, before treatment (curve A) and after treatment (curve B).

For the natural (or native) fir sample (curve A), the maximum stress at rupture was measured at 175 kgf/cm2 and the deformation arrow was 0.53 cm.

In contrast, for the translucent composite fir sample of the invention (curve B), the maximum stress at rupture was measured at 350 kgf/cm2 and the deformation arrow was 0.65 cm.

Thus, the cellular densification of the fir through the invention treatment allowed a 200% resistance to increased bending effort. Furthermore, unlike the native fir, the break is more gradual in the case of the invention composite fir material. Therefore, the material gained ductility through the invention treatment. Without wanting to be limited by any theory, the inventor thinks this is probably due to a strong adhesion between the fibers and the polymer matrix.

Measurement of axial compression as illustrated in Figures 19 and 20

This measurement was carried out on samples of fir of dimensions 1 cm x 3,5 cm x 10 cm (IxLxh), using a method developed by the applicant.

Figure 19 shows the principle diagram for measuring the axial compression of the fir sample forming the composite fir structure (41) of the invention.

As shown in Figure 19, a compression force F was applied to the sample (41) by a crushing plate (40) of 7 cm diameter, increasing in strength, parallel to its main axis, and the maximum stress just before rupture (distance da) was measured.

Figure 20 shows the result of this measurement of the axial compression of the fir sample, before treatment (curve A) and after treatment (curve B).

For the natural (or native) fir sample (curve A), the maximum stress at rupture was measured at 254 kgf/cm2 and the deformation just before rupture was 0.959 cm.

In contrast, for the translucent composite fir sample of the invention (curve B), the maximum stress at rupture was measured at 430 kgf/cm2 and the deformation just before rupture was 0.978 cm.

Thus, the cellular densification of the fir through the treatment according to the invention allowed a resistance to an increased axial compression effort of 170%. Furthermore, unlike the native fir, the rupture is more gradual in the case of the composite fir material according to the invention. Without wanting to be limited by any theory, the inventor thinks that this is probably due to the nature of the composite fir, which leads to the fact that the appearance of a crack in the matrix is stopped by polymer-reinforced wood fibers.

Measurement of axial tensile strength as shown in Figures 21 and 22

This measurement was carried out on samples of fir measuring 0,2 cm x 3 cm x 7,5 cm (IxLxh), using a method developed by the applicant.

Figure 21 shows the principle diagram for measuring the axial tensile strength of the fir sample forming the composite fir structure (43) of the invention.

As shown in Figure 21, two identical forces of opposite direction F of tensile force were applied to the sample by means of two identical, increasingly stronger claws (42) parallel to its main axis and the maximum stress before rupture was measured.

Figure 22 shows the result of this measurement of the axial tensile strength of the fir sample, before treatment (curve A) and after treatment (curve B).

For the natural (or native) fir sample (curve A), the maximum stress at rupture was measured at 125 kgf/cm2 and the extension just before rupture was 0.7 cm.

In contrast, for the translucent composite fir sample of the invention (curve B), the maximum stress at rupture was measured at 165 kgf/cm2 and the expansion before rupture was 0.7 cm.

The plastic deformation recorded was about 6% before rupture, so that the behaviour of the material according to the invention under axial tensile stress is substantially the same as that of the material before treatment.

Optical tests illustrated by Figures 15, 16 and 23

The composite fir structure obtained in example 1 was translucent.

Figures 15 and 16 show, at two different scales, scanning electron microscope (SEM) photographs of a part of a fir tree structure treated in example 1 at different stages of the treatment process according to the invention.

Figure 15 shows three scanning electron microscope (SEM) photographs of a part of the fir structure at different stages of the treatment process according to the invention, i.e. from left to right before delignification (natural or native wood), after delignification and before monomer impregnation, and after polymerization of the monomer compound impregnated, respectively.

The clear parts that fill after impregnation of the filling compound are different after impregnation, in particular whiter and wider (see comparison between parts 30 and 31 of Figure 15 and between parts 36 and 34 of Figure 16).

The dark parts (32 for the second photograph in Figure 15, 33 for the third photograph in Figure 15, 37 for the first photograph in Figure 16 and 35 for the second photograph in Figure 16) correspond to air and could be considerably reduced by further optimization of the process. These photographs show the disorderly state of the wood before delignification, which makes it impossible to distinguish the cell cavities, the more orderly state of the wood after delignification, where the cell cavities are clearly distinguished, and the state of the wood cavities partially filled with polymer after the invention process.

Figure 23 shows two photographs with Zeiss LSM710 Upright microscope with a 20 x lens of the composite fir structure, in radial longitudinal cut (CLR) and in transverse cut (CT).

The room lighting is 257 lux.

The first photograph is in radial longitudinal cut-out (RLC) obtained with 14 lux of direct light transmission for the ambient lighting considered (i.e. 5,5% of light transmission), while the second photograph of this sample is in transverse cut-out (CT) obtained with 27 lux of direct light transmission for the ambient lighting considered (i.e. 11% of light transmission).

These two photographs show that the composite wood is a three-dimensional structure, i.e. that regardless of the cutting plan, the translucent character of the composite fir appears.

Example 3: Optical evaluation of composite structures of white pine, white oak, mahogany, lime and ash obtained by a treatment according to the invention as in example 1

The treatment procedure in example 1 was repeated on other wood species, namely on samples forming structures composed of five species: white pine, white oak, mahogany, lime and ash.

Figure 23 shows eight photographs with Zeiss LSM710 Upright microscope with a 20 x lens of composite wood structures made from these five essences.

The first photograph of the white pine sample is in radial longitudinal cut-out plane (CLR) obtained with 20 lux of direct light transmission for the ambient lighting considered (i.e. 8% of light transmission), while the second photograph of this sample is in transverse cut-out plane (CT) obtained with 65 lux of direct light transmission for the ambient lighting considered (i.e. 25% of light transmission).

The only photograph of the white oak sample is in CT obtained with 22 lux of direct light transmission for the ambient lighting considered (or 9% of light transmission).

The only photograph of the mahogany sample is in CT obtained with 33 lux of direct light transmission for the ambient lighting considered (i.e. 13% of light transmission).

The first photograph of the lime sample is in radial longitudinal cut-out plane (CLR) obtained with 30 lux of direct light transmission for the ambient lighting considered (i.e. 12% of light transmission), while the second photograph of this sample is in transverse cut-out plane (CT) obtained with 70 lux of direct light transmission for the ambient lighting considered (i.e. 30% of light transmission).

The first photograph of the ash sample is in radial longitudinal cut-off (RLC) obtained with 11 lux of direct light transmission for the ambient lighting considered (i.e. 4,3% of light transmission), while the second photograph of this sample is in transverse cut-off (CT) obtained with 33 lux of direct light transmission for the ambient lighting considered (i.e. 13% of light transmission).

In each case, these photographs show that the composite wood is a three-dimensional structure i.e. that regardless of the cutting plan, the translucent character of the composite wood appears.

It would be possible to improve the light transmission of composite wood by refining the process by the craftsman, particularly as regards the control of delignification, the depth of saturation/fill and the nature of the filling compound, the refractive index of which, when processed, must be almost homogeneous with the refractive index of the composite ligno-cellulosic substrate.

Claims (15)

1. A treatment process for treating a structure of lignocellulosic material, the lignocellulosic material being preferably wood, said process comprising the following steps:

   (1) at least one step of soaking the structure of lignocellulosic material with at least one fluid to dissolve at least 40% and at most 85% by weight % of the lignin present in the material;

   (2) at least one step of washing the structure resulting from step (1) with at least one organic fluid so as to discharge the dissolved lignin resulting from the soaking step (1), so as to produce a partially delignified structure;

   (3) at least one step of filling the partially delignified structure resulting from the washing step (2) with at least one filling compound, so as to produce a filled partially delignified structure; and

   (4) at least one step of finishing the filled partially delignified structure resulting from the filling step (3), so as to obtain a composite material structure formed of a three-dimensional network of transformed filling compound incorporated in a network of cellulose and lignin.
2. A treatment process according to claim 1, wherein the structure of lignocellulosic material is a trimming member, a finishing member or a structure member.
3. A treatment process according to one of claims 1 and 2, wherein the fluid of soaking step (1) is chosen from:

   - an aqueous solution comprising a mixture of sodium chloride and sodium hydroxide, or an aqueous liquid comprising monoethanolamine, or a basic solution comprising KOH;

   - an aqueous solution comprising a mixture of acetic acid and hydrogen peroxide, or an acidic solution comprising HBr, H₂SO₄ or H₃PO₄;

   - a fluid comprising at least one enzyme, possibly in the presence of at least one ionic liquid or in the presence of at least one ionic liquid and at least one cosolvent;

   - a pure ionic liquid;

   - an ionic liquid containing one or more enzymes in solution;

   - an ionic liquid in a mixture with at least one solvent miscible with the ionic liquid;

   - an ionic liquid in a mixture with at least one miscible solvent containing one or more enzymes in solution;

   - a biphasic system, of which one of the phases is constituted by an ionic liquid, pure or mixed with at least one miscible solvent, and the other phase is constituted by a supercritical fluid;

   - a biphasic system, of which one of the phases is constituted by an ionic liquid, pure or in a mixture with at least one miscible solvent, and the other phase is constituted by a supercritical fluid, furthermore containing one or more enzymes in solution in the phase containing the ionic liquid; and

   - any solution of a pure compound or of a mixture of compounds, containing at least one enzyme; and mixtures thereof.
4. A treatment process according to one of claims 1 to 3, wherein the soaking step is preceded by a prior treatment step, comprising at least one sub-step of pre-soaking a structure of lignocellulosic material with at least one organic fluid; followed by at least one sub-step of pre-washing of the structure resulting from the pre-soaking sub-step, with at least one organic fluid, so as to discharge the dissolved compounds resulting from the sub-step of pre-soaking.
5. A treatment process according to one of claims 1 to 4, wherein the organic fluid of the washing step (2) is a liquid chosen from the group formed by ethanol, hexane, isopropanol, heptane and mixtures thereof.
6. A treatment process according to one of claims 1 to 5, wherein the filling compound of the filling step (3) is in the liquid state under the conditions of pressure and temperature of the filling step (3), to carry out the filling step (3) by soaking the partially delignified structure in the liquid co-polymer or polymer.
7. A treatment process according to one of claims 1 to 6, wherein the filling compound of the filling step (3), is a polymerizable monomer present in a monomeric solution at the conditions of pressure and temperature of the filling step (3), the monomer solution further comprising at least one catalyst.
8. A treatment process according to claim 7, wherein the monomeric solution of the filling step (3) comprises at least one monomer chosen from:

   - monomers produced from petroleum among which are methacrylates, phthalates; nitriles; styrene and styrenic derivatives; vinyl compounds; ethylenic compounds; butadiene; isoprene; and

   - bio-sourced monomers among which are terpenes; glycerol and glycerol derivatives obtained after reaction with at least one of epichlorohydrin, isomers of propanediol and glycolic acid; derivatives of sugars; furfural derivatives; lactic and formic acid derivatives; monomers produced from castor oil; hydroxyalkanoic acids; bio-ethylene; bio-ethylene glycol; bio-propylene; bio-1,4-butanediol; lignin derivatives; and mixtures thereof.
9. A treatment process according to one of claims 1 to 8, wherein the dissolved lignin recovered from the organic fluid of washing step (2) is used in a process of exploiting the lignin for the manufacture of a construction material or of a material used in aeronautics or of a packaging material or of a biofuel or of a pharmaceutical compound or of a chemical compound.
10. A treatment process according to one of claims 1 to 9, wherein the lignocellulosic material is softwood and 50 to 85 %, preferably 50 to 75%, by weight %, of the lignin present in the structure is dissolved during the soaking step (1).
11. A treatment process according to one of claims 1 to 9, wherein the lignocellulosic material is hardwood and 40 to 60 %, preferably 45 to 55 %, by weight %, of the lignin present in the structure is dissolved during the soaking step (1).
12. A composite material structure (62) comprising lignin, hemicellulose, cellulose and at least one filling compound, said structure being obtainable by the implementation of the treatment process according to one of claims 1 to 11, wherein the composite material structure forms a three-dimensional network of transformed filling compound (59) incorporated in a structure (44', 45, 47, 46) of cellulose and lignin.
13. A material structure according to claim 12, such that the structure is substantially translucent.
14. A material structure according to one of claims 12 and 13, such that the structure is a trimming member, a finishing member or a structure member.
15. A part comprising at least one composite material structure (62) according to one of claims 12 to 14, said part being an item of furniture or part of an item of furniture, a component of a building, a automotive part or an aeronautical part.