AU2023278471A1

AU2023278471A1 - Method for acylating a hydroxylated solid material

Info

Publication number: AU2023278471A1
Application number: AU2023278471A
Authority: AU
Inventors: Daniel Samain
Original assignee: Cellulotech Inc
Current assignee: Cellulotech Inc
Priority date: 2022-05-31
Filing date: 2023-05-31
Publication date: 2024-08-29
Also published as: WO2023233202A1; FR3135980A1; CN118805010A

Abstract

The invention relates to a method for chromatogenic acylation of a solid material (1, 2) carrying hydroxyl groups capable of reacting with fatty acid chlorides in the gaseous state, wherein: a reactive fatty acid chloride composition (20, 21, 22) is applied to the surface of the solid hydroxyl material (1, 2) by means of an applicator capable of releasing the composition (20, 21, 22) on the surface of the material (1, 2). According to the invention, the composition (20, 21, 22) is applied to the surface of the solid hydroxyl material (1, 2) at an acylation temperature lower than the vaporisation temperature of at least one fatty acid chloride of the composition (20, 21, 22) to allow acylation of the material (1, 2) by reaction of at least one fatty acid chloride in the gaseous state of the composition (20, 21, 22) with at least one of the hydroxyl groups of the material (1, 2), the acylation temperature being between 160°C and 250°C.

Description

Description Title of the invention: METHOD FOR ACYLATING A HYDROXYLATED SOLID MATERIAL

[0001] The invention relates to a process for the chromatogenic acylation of a hydroxylated solid material, i.e. a solid material bearing reactogenic hydroxyl (-OH) groups), which are ac cessible and capable of reacting with a fatty acid chloride in the gaseous state.

[0002] Throughout the text, the term "chromatogenic" and the expression "by chromatogeny" de scribing the acylation reaction, indicate and recall that this acylation reaction or more simply "acylation" occurs between a hydroxylated solid material such as a paper support considered in the field of separative gas chromatography (GC), as the stationary phase and a fatty acid chloride reagent at least partially in the gaseous state and considered as an elu ate entrained in liquid/vapor equilibrium by the mobile gas phase consisting of a flow of a hot gas phase.

[0003] A semi-industrial process is known from WO2012/066015 for the chromatogenic acylation of a web of a cellulosic substrate such as paper, moved between an upstream reel and a downstream take-up roll. According to this semi-industrial process, fatty acid chloride (R CO-Ct) in the liquid state is deposited at an upstream fixed station by means of a cylinder, known as an anilox roller, on the paper of the moving paper web and is then heated down stream of the deposition to a temperature enabling acylation. A fraction of fatty acid chlo ride changes to the gaseous state due to the increase in the saturation vapor pressure of the fatty acid chloride, related to the increase in the heating temperature. The gaseous fatty acid chloride reacts with reactogenic hydroxyls of the paper to form ester bonds between the paper and the hydrocarbon chain (R) of the fatty acid chloride according to the follow ing equation (I): Paper-OH + R-CO-CI ' Paper-O-CO-R +HC (I).

[0004] The chromatogenic acylation is advantageously carried out with no organic solvent and no catalyst so that it is not necessary to remove them on conclusion of the reaction. The acyla tion is promoted by the removal of gaseous hydrochloric acid (HC) produced by the acyl ation, which is entrained by the application of a stream of hot air over the cellulosic sub strate being acylated. Entraining the gaseous hydrochloric acid formed makes it possible to shift the equilibrium of the reaction in the direction of formation of the acylated cellulosic substrate.

[0005] However, the inventor has found that the process of WO2012/066015 is not optimized.

Firstly, the acylated cellulosic substrate according to W02012/066015 has a hydrophobi city that is qualitatively lower than that of an acylated cellulosic substrate obtained by im pregnating the substrate with a solution of fatty acid chloride in pentane and then heating the impregnated substrate by applying a hot gas stream. This process does not make it pos sible to give the cellulosic substrate a hydrophobicity and, where appropriate, an imperme ability to water which are optimal and and sufficiently durable over time. It was found that the contact angle of a drop of pure water deposited on the surface of an acylated cellulosic substrate according to the process of WO2012/066015 is certainly greater than 90, but re mains lower than the optimum value of 150° obtained by applying the solution of fatty acid chloride in pentane. This results in unsatisfactory hydrophobicity properties. Secondly, it does not make it possible to effectively acylate the paper of a paper web -in particular a web of special paper of high grammage and/or of porous paper having a high specific sur face area and/or of paper having a surface layer of polyvinyl alcohol - moved with a speed of greater than 50 meters per minute. The process of WO2012/066015 is in fact incompati ble with implementation on an industrial scale. Indeed, the optimal acylation of such a pa per web could only be obtained at the expense of excessive deposition of fatty acid chlo ride and/or excessive heating of the paper, which will inevitably lead to deterioration and/or browning of the latter.

[0006] The invention aims to overcome the abovementioned drawbacks of the process of W02012/066015.

[0007] Also known from W02022/033698 is a process for solvent-free chromatographic acylation of a piece of paper heated to a temperature of 160°C and on which stearic acid chloride in the liquid state is deposited by means of an applicator roller, the application surface of which is formed of a pile. In this process, neither the pile nor the applicator roller are heated, so that the stearic acid chloride loaded on the pile is inevitably at a temperature be low the acylation temperature during deposition, in particular at a temperature between room temperature and the acylation temperature. The piece of paper is then subjected to a subsequent heat treatment for completion of the acylation. The process of W02022/033698 makes it possible to impart satisfactory hydrophobicity properties to the acylated piece. However, the process of W02022/033698 is not completely set up to enable the acylation of the paper of a paper web moved at very high speed, in particular at a run speed of greater than 100 meters per minute. Despite the improvements made by W02022/033698, ungrafted liquid fatty acid chloride inevitably remains on the paper. On the one hand, such an excess is not economically acceptable. Such an excess is not functionally acceptable ei ther. The residual liquid fatty acid chloride is likely to be hydrolysed during prolonged storage of the acylated paper by releasing hydrochloric acid. The released hydrochloric acid can damage the cellulose fibers and cellulosic material, adversely affecting its me chanical strength. In addition, the fatty acid released via this hydrolysis reduces the hydro phobicity and water impermeability of the acylated paper. This excess must therefore be eliminated. The process of W02022/033698 must be optimized and its economic effi ciency must be improved.

[0008] The invention aims to overcome this drawback.

[0009] The invention therefore aims to provide an improved process fo rthe chromatogenic acyla tion of a solid material bearing hydroxyl groups that are accessible to at least one fatty acid chloride in the gaseous state and that are capable of reacting with this (these) fatty acid chloride(s) in the gaseous state.

[0010] The invention therefore aims to provide such a chromatogenic acylation process, the acyla tion efficiency of which is improved.

[0011] The invention also aims to provide such an improved process that makes it possible to in crease the rate of chromatogenic acylation.

[0012] The invention also aims to provide such a chromatogenic acylation process that makes it possible to give a hydroxylated solid material satisfactory hydrophobicity properties.

[0013] In particular, the invention aims to provide such a chromatogenic acylation process that makes it possible to give a hydroxylated solid material satisfactory hydrophobicity proper ties with a reduced amount of fatty acid chloride.

[0014] However, the invention also aims to provide such a process for chromatogenic acylation of a hydroxylated solid material and transformation of this hydroxylated solid material into an acylated material substantially of the same porosity as the starting hydroxylated solid mate rial.

[0015] The invention aims to provide such a process for the chromatogenic acylation of a hydrox ylated solid material capable of being carried out in an artisanal manner by any individual with commonly accessible means.

[0016] However, the invention also aims to provide an industrial process for acylation of a width of paper while it is moving between an upstream reel of said width of paper and a down stream take-up roll device for a width of acylated paper.

[0017] In particular, the invention therefore aims to provide such an industrial chromatogenic ac ylation process that is compatible with the technical constraints relating to the movement of the solid material and to a high rate of production of such an acylated solid material.

[0018] The invention aims in particular to provide such a process that makes it possible to deposit the desired amount - in particular a large amount, in the case of special solid materials - of fatty acid chloride, while allowing the solid material to travel at high speed.

[0019] In addition, the invention also aims to provide such a chromatogenic acylation process which does not require, for the implementation thereof, the use of an organic solvent toxic to the environment, in particular a nonpolar organic solvent.

[0020] However, the invention also aims to provide such a chromatogenic acylation process that makes it possible to limit the amount of residual fatty acid chloride at the end of the acyla tion.

[0021] The invention also aims to provide such a chromatogenic acylation process that makes it possible to deposit an optimum amount of reactive fatty acid chloride, relative to the num ber and/or density of reactogenic hydroxyls, which are accessible and capable of reacting with the fatty acid chloride in the gaseous state.

[0022] The invention thus aims to provide such a chromatogenic acylation process enabling a sub stantially stoichiometric acylation of the reactogenic hydroxyls of the solid material.

[0023] The invention also aims to provide such a chromatogenic acylation process enabling acyla tion of various solid materials, in particular special solid materials such as corrugated board and/or papers coated with polyvinyl alcohol.

[0024] The invention also aims to provide such a chromatogenic acylation process that makes it possible to reduce or even completely eliminate the step of removing excess fatty acid chloride.

[0025] The invention therefore aims in particular to provide such a simplified process as long as it does not require a final step of removing residual ungrafted fatty acid chloride.

[0026] To this end, the invention relates to a process for the chromatogenic acylation of a solid material bearing hydroxyl groups that are accessible to at least one fatty acid chloride in the gaseous state and that are capable of reacting with this (these) fatty acid chloride(s) in the gaseous state, wherein: at least one composition, referred to as reactive composition, of at least one fatty acid chlo ride is applied at least on the surface of said hydroxylated solid material by means of at least one applicator device - notably an applicator roller - having an application surface formed of filiform elements that are not reactive with said reactive composition and that are able to release - and apply - said reactive composition at least on the surface - i.e. on the surface and where appropriate at depth over at least one thickness portion - of said hy droxylated solid material by contact of the filiform elements - notably by contact of the fil iform elements rotated by the roller - and the hydroxylated solid material; characterized in that said reactive composition applied - notably released in contact with said hydroxylated solid material - by the applicator device at least on the surface of said hydroxylated solid material is, during the application thereof, at a temperature, referred to as acylation temperature, below the vaporization temperature of at least one - notably of each - fatty acid chloride of said reactive composition and chosen to enable an acylation of said solid material by reaction of at least one - notably of each - fatty acid chloride in the gaseous state of said reactive composition with at least one of the hydroxyl groups of said solid material, said acylation temperature being between 160°C and 250°C.

[0027] The inventor has discovered that, completely surprisingly and counterintuitively, it is actu ally advantageous to apply, that is to say to deposit and distribute, said reactive composi tion on the hydroxylated solid material by ensuring that said reactive composition applied is at said acylation temperature of between 160°C and 250°C during application, i.e. at a temperature high enough to enable the acylation of the hydroxylated solid material by acid chloride in the gaseous state, without passing through a prior step of depositing said reac tive composition in the liquid state, by means of an applicator device necessarily chosen and intended to allow the application of a liquid composition. The inventor has realized that the filiform elements forming the application surface of the applicator device - in par ticular of a roller or brush - used in the context of the present invention, when impregnated with said reactive composition brought to said acylation temperature of between 160°C and 250°C - above the deposition and distribution temperature described in W02022/033698 and briefly brought into contact with the surface of the hydroxylated solid material, itself brought to said acylation temperature, allows a more effective acylation of the hydrox ylated solid material than when said liquid reactive composition is deposited at low tem perature in essentially liquid form and then heated after deposition to said acylation tem perature. The inventor has observed that bringing the hydroxylated solid material into con tact with said reactive composition at said acylation temperature makes it possible to in crease the rate of the acylation reaction, making it compatible with an implementation of the process on an industrial scale, enabling the acylation of the moving hydroxylated solid material of a web of hydroxylated solid material, in particular of the paper of a paper web. Although said high acylation temperature shifts the liquid/vapor equilibrium of the fatty acid chloride(s) of said reactive composition in the direction of an increase in the gaseous fraction of said reactive composition, this gaseous fraction, which could be expected to dif fuse freely at a distance from the filiform elements of the applicator device and the hydrox ylated solid material, rendering it unreactive with respect to this hydroxylated solid mate rial, appears to remain in fact confined within the filiform elements and seems to react ef fectively and very rapidly with the hydroxylated solid material. The filiform elements forming the application surface of the applicator device seem to behave like a reservoir of fatty acid chloride(s) in the gaseous state, the fatty acid chloride(s) in the gaseous state seeming to be retained by the filiform elements. Moreover, increasing the reaction rate of the fatty acid chloride in the gaseous state with the hydroxyls of the hydroxylated solid ma terial makes it possible to shift, with an equivalent time constant, the liquid/vapor equilib rium of the fatty acid chloride in the direction of vaporization. The reaction is consequently also improved and accelerated.

[0028] This increase in the rate of acylation reaction makes it possible to carry out a plurality of successive deposits of fatty acid chloride(s) on the hydroxylated solid material and at said acylation temperature, in particular on the moving paper of a paper web, each deposit of the plurality of deposits providing a substoichiometric amount of fatty acid chloride(s) rel ative to the reactogenic hydroxyls of the hydroxylated solid material. In these embodi ments, the stoichiometric amount of fatty acid chloride(s) can be reached owing to the mul tiplicity of successive deposits. In addition, each substoichiometric deposit of fatty acid chloride(s) makes it possible, during each deposit, to promote the dispersion of the fatty acid chloride(s) deposited at said acylation temperature on the surface of the hydroxylated solid material, thus promoting its reactivity.

[0029] But even more surprisingly, without this observation being supported by a known theory, the retention of fatty acid chloride(s), in particular fatty acid chloride(s) in the gaseous state, in the region of the filiform elements does not seem to prohibit the interaction of fatty acid chloride(s) in the gaseous state and the hydroxylated solid material. The fact that the filiform elements trapping the fatty acid chloride(s) in the gaseous state come into con tact with the surface of the hydroxylated solid material seems to break the confinement of said reactive composition, in particular its gaseous fraction, in the filiform elements and allows a rapid reaction, promoted by the high temperature of said reactive composition, with the hydroxyls of the hydroxylated solid material. According to the expression used by the inventor, the gaseous fraction of the fatty acid chloride(s) of said reactive composition appears to be "sucked up" by the hydroxylated solid material.

[0030] This apparent phenomenon of sucking up the fatty acid chloride(s) in the gaseous state that are confined in the filiform elements seems to make it possible in fact to overcome the ef fect of a gaseous layer, referred to as gaseous boundary layer, extending on the surface of the hydroxylated solid material and limiting, or even opposing, the approach, by diffusion, of the fatty acid chloride(s) in the gaseous state as far as the reactive hydroxyls of the hy droxylated solid material. The use of an applicator device - notably a roller or a brush having an application surface formed of filiform elements seems to make it possible to de- posit and distribute fatty acid chloride(s) in the gaseous state in contact with the hydrox ylated solid material while overcoming the effect of said boundary layer. The applicator device heated to said acylation temperature makes it possible to solve the problem not solved until now of the existence of said boundary layer on the surface of the hydroxylated solid material.

[0031] The process according to the invention makes it possible to give the solid material satisfac tory or even excellent hydrophobicity properties, in particular as evaluated by measuring the Cobb value and/or by measuring the contact angle formed by a drop of water deposited on the surface of the acylated solid material and/or by testing the tightness of a pocket of water.

[0032] But it also makes it possible, in the context of the chromatogenic acylation of a hydrox ylated solid material of great thickness and/or of high porosity and/or of large specific sur face area, such as a paper material of high grammage, a corrugated board or a solid mate rial coated with polyvinyl alcohol, to carry out a plurality of successive hot depositions al lowing a substantially stoichiometric acylation of the hydroxylated solid material of great thickness and/or of high porosity and/or of large specific surface area.

[0033] According to certain embodiments of a process according to the invention, at least one ap plication surface portion of the applicator device is in contact with a surface portion of the hydroxylated solid material, at least this surface portion of the hydroxylated solid material is at said acylation temperature during application of said reactive composition to the hy droxylated solid material. According to these embodiments of a process according to the invention, the solid material is heated prior to the application of said reactive composition. In these embodiments, the solid material is heated in the absence of said reactive composi tion. Advantageously, the heating of the solid material prior to the application of said reac tive composition allows an at least partial dehydration of the solid material.

[0034] According to certain embodiments of a process according to the invention, the filiform ele ments forming the application surface are at said acylation temperature during the applica tion of said reactive composition to the hydroxylated solid material.

[0035] According to certain embodiments of a process according to the invention, said reactive composition is applied at least on the surface of said hydroxylated solid material, in a ther moregulated chamber suitable for maintaining said reactive composition released by the applicator device at said acylation temperature.

[0036] According to certain embodiments, the process according to the invention comprises at least one step of redistributing fatty acid chloride(s) deposited on the hydroxylated solid material, without a fresh supply of said reactive composition, the redistribution step being carried out by means of at least one distributor device having an application surface formed of filiform elements which are not reactive with the fatty acid chlorides of said reactive composition and are able to be loaded with fatty acid chlorides deposited on the hydrox ylated solid material, by contact of the filiform elements of the distributor device with the hydroxylated solid material and in order to release at least some of the loaded fatty acids, in contact with said hydroxylated solid material by contact of the filiform elements with the hydroxylated solid material, the distributor device being at a temperature of between 160°C and 250°C. Such a high-temperature redistribution step favors the gaseous state of the fatty acid chloride(s) previously supplied and the reactivity thereof.

[0037] Advantageously, the filiform elements of the applicator device and/or of the distributor de vice are flexible and deformable in contact with the hydroxylated solid material and are suitable, owing to this flexibility, this deformation and the displacement of the applicator device and/or of the distributor device relative to the hydroxylated solid material, for re leasing fatty acid chloride at the surface and at depth over at least one portion of the thick ness of the hydroxylated solid material or for removing fatty acid chloride from this sur face.

[0038] According to certain embodiments of a process according to the invention, the application surface of the applicator device and/or the distributor device is formed of a pile provided with the filiform elements. The material forming the filiform elements is also chosen to withstand said acylation temperature, without loss of the adsorbent and/or application properties thereof.

[0039] According to certain embodiments of a process according to the invention, said acylation temperature is between 160°C and 250°C, in particular between 165°C and 240°C, particu larly between 170°C and 230°C, more particularly between 180°C and 220°C, preferably between 190°C and 220°C, more preferentially between 200°C and 220°C. Said acylation temperature is adapted according to the solid material to be acylated. In particular, said ac ylation temperature is chosen to be below the browning temperature of the solid material. That being said, according to the invention, considering the rate of acylation due to the hot deposition of said reactive composition and the reduced duration of exposure of the solid material to high temperature, the risks of browning of the solid material due to the high temperature are reduced.

[0040] According to certain embodiments of a process according to the invention, at least one notably each - reactive composition comprises at least one fatty acid chloride chosen from the group formed of palmitic acid chloride (C 16), stearic acid chloride (C18 ), arachidic acid chloride (C 2 0) and behenic acid chloride (C 2 2 ). There is nothing to prevent said reactive composition from comprising a small proportion of acetyl chloride (CH 3 -CO-Cf). The in ventor has discovered that acetyl chloride, which is not a fatty acid chloride within the meaning of the invention, is capable of reacting spontaneously and rapidly with free water molecules present in the solid material while protecting the fatty acid chlorides intended for acylation from possible hydrolysis. The inventor has also observed that, surprisingly, acetyl chloride reacts neither with the free and accessible hydroxyl groups of the solid ma terial, nor with said reactogenic hydroxyls of other hydroxylated polymers such as polyvi nyl alcohol. Furthermore, advantageously, the acetic acid produced by hydrolysis of acetyl chloride is sufficiently volatile to be removed from the solid material. Advantageously, ac etyl chloride is used as a protector of the fatty acid chloride(s) of said reactive composition. Advantageously, acetyl chloride is used as a trans-chlorination reagent for restoring fatty acid chlorides from hydrolyzed free fatty acids.

[0041] In certain embodiments of a process according to the invention, the hydroxylated solid ma terial is a paper material. It may be a hydroxylated solid material - that is to say a material which is neither liquid nor gaseous - essentially consisting of cellulose and having free hy droxyl groups, which are accessible and reactive with respect to fatty acid chlorides in the gaseous state. The hydroxylated solid material may also be a hydroxylated solid material in particular a paper or a board, for example a corrugated board - having an outer surface layer formed of polyvinyl alcohol.

[0042] Said reactive composition(s) can be applied to the hydroxylated solid material with a total amount chosen so that the hydroxylated solid material has a deposited surface amount of fatty acid chloride(s) of between 1 mg and 500 mg per square meter (mg/m 2 ) of geometric surface area of said hydroxylated solid material. The amount of fatty acid chloride(s) ap plied to the hydroxylated solid material is between 1 mg/m2 and 500 mg/m2 of hydrox ylated solid material. Advantageously, a plurality of successive depositions are carried out at said acylation temperature so as to achieve a substantially stoichiometric acylation of the hydroxylated solid material.

[0043] In certain embodiments, the applicator device is an applicator brush, the filiform elements of which are chosen to withstand said acylation temperature. In these embodiments, the process according to the invention can be carried out manually in an artisanal manner.

[0044] According to certain industrial-scale embodiments of a process according to the invention, the hydroxylated solid material is formed of a web of paper moved in a run direction paral lel to the largest dimension of the web, between an upstream reel of said paper web and a downstream take-up roll for a web of acylated paper. The increased reactivity of the acid chloride(s) deposited at high temperature enables the implementation of the process ac cording to these embodiments. In these embodiments, the paper of the web of paper can be moved at a high run speed, in particular greater than 50 m/min, preferably greater than 100 m/min. In these embodiments, at least one - in particular each - reactive composition is ap plied at fixed station(s) at least on one main face of the moving paper web. According to these industrial-scale embodiments of a process according to the invention, the reactive composition(s) is/are applied on the go by means of an applicator device which is fixed and immobile with respect to the moving paper. According to these industrial-scale embod iments of a process according to the invention, at least one - in particular each - applicator device - is a roll with an axis of rotation parallel to the plane of the paper web and non-par allel - in particular orthogonal - to the run direction. According to some of these embodi ments, when the web of paper is a web of low-grammage paper, said reactive composi tion(s) is (are) applied to the web of paper with a total amount selected such that the web of paper has an average surface amount of fatty acid chloride(s) of between 1 mg and 50 mg per square meter (mg/m 2 ) of planar (geometric) surface area of the web of paper. That be ing said, according to certain other embodiments, when the web of paper is a web of board - in particular corrugated board - or a web of paper coated with polyvinyl alcohol, said re active composition(s) is (are) applied to the web of paper with a total amount selected such that the web of paper has an average surface amount of fatty acid chloride(s) of greater than 50 mg per square meter (mg/m 2 ) of planar surface area of the web of paper, in particu lar which may reach 500 mg/m 2 , and that is suitable for allowing a (stoichiometric) acyla tion of almost all of the reactogenic hydroxyls.

[0045] In certain embodiments, the process according to the invention comprises at least two ap plications of reactive composition(s) at fixed stations on the moving paper web, each reac tive composition being at said acylation temperature during the application thereof. Ac cording to this embodiment of a process according to the invention, a small amount of fatty acid chloride(s) is applied at said acylation temperature to enable a rapid and substantially quantitative acylation and this application is repeated several times to achieve a substan tially stoichiometric acylation of the paper of the paper web.

[0046] In certain embodiments, the solid material is a paper material coated with polyvinyl alco hol. The increased reactivity of the acid chloride(s) deposited at high temperature makes it possible to carry out the process according to these embodiments, including when the sur face polyvinyl alcohol is at a temperature above its melting temperature and is in a tacky state.

[0047] According to certain embodiments of a process according to the invention, thefiliform ele ments are formed of at least one material chosen from the group formed of aramid fibers and microfibers - in particular Kevlar@ (micro)fibers - and inorganic fibers and microfibers - in particular glass (micro)fibers and carbon (micro)fibers. The filiform elements are formed of at least one fibrous or microfibrous material which is temperature-resistant, re sistant to acid media and resistant to the abrasion caused by the movement of the paper web. The filiform elements are formed of at least onefibrous or microfibrous material which is inert toward the fatty acid chloride(s) of said reactive composition.

[0048] According to certain embodiments of a process according to the invention, at least one por tion of gaseous hydrochloric acid formed due to the chromatogenic acylation is entrained by a flow of a gaseous composition circulating in contact with the solid material - notably countercurrent to the moving web of paper - at said acylation temperature. Entraining away the gaseous hydrochloric acid formed by the chromatogenic acylation reaction makes it possible to shift the equilibrium of the reaction in the direction of acylation of the hydrox ylated solid material and/or paper material. Moving the hydrochloric acid formed makes it possible to prevent a deterioration of the cellulose fibers of the paper material and more generally of the solid cellulose material and deterioration of its mechanical strength quali ties, the hydrochloric acid formed and not moved being liable to promote hydrolysis of es ter bonds and release of acylation groups in the form of free fatty acids. Moving the hydro chloric acid formed also makes it possible to prevent the fatty acids released due to this hy drolysis from adversely affecting the barrier properties of the acylated solid material.

[0049] According to certain other embodiments of a process according to the invention, the fili form elements of at least one applicator roller are supplied by centrifugal diffusion of said reactive composition from an axial lumen of this applicator roller rotated upon itself. In some of these embodiments, said reactive composition is introduced into the axial lumen of the applicator roller by means of a bar for distributing said reactive composition over sub stantially the entire length of the axial lumen, the distribution bar extending over substan tially the entire length of the axial lumen. According to certain embodiments, the distribu tion bar is swingably mounted along the longitudinal axis of the distribution bar and along the axis of rotation of the applicator roller.

[0050] In these embodiments, the axial lumen of the applicator roller is suitable for accommodat ing a bar for supplying the applicator roller with reactive composition and for distributing said reactive composition over the entire length of the axial lumen. The distribution bar may be provided with orifices for dispersing said reactive composition, distributed along the distribution bar so as to be able to dispense said reactive composition over the entire length of the axial lumen of the applicator roller.

[0051] Any other mode of supplying the filiform elements is possible. According to certain other embodiments of a process according to the invention, the filiform elements are suitable for being loaded with said reactive composition by contact between the - in particular rotated (external) application surface of the applicator device and a device for dispensing said re active composition. In some of these embodiments, the dispensing device may comprise a printing device comprising a cylinder, known as an anilox roller, having a plurality of re cessed cells formed on the outer surface of said anilox roller and of predetermined dimen sions and volumes suitable for controlling the amount of said reactive composition trans ferred onto the applicator device.

[0052] In certain advantageous embodiments, at least one applicator roller is provided with means for heating said reactive composition to said acylation temperature. In these advantageous embodiments, the filiform elements forming the application surface of the roller advanta geously act as an applicator reservoir for fatty acid chloride(s), in particular fatty acid chlo ride(s) in the gaseous state.

[0053] According to certain embodiments of a process according to the invention, at least one ap plicator roller is rotated with an angular speed of rotation chosen so that the peripheral ends of the filiform elements are rotated with a linear speed having a value different from the value of the run speed of the paper web. In these other embodiments,the linear run speed of the free ends of the filiform elements and the run speed of the paper web are not synchronized. The application of said reactive composition at the surface of and at depth on the solid material by light contact of said surface and projecting said reactive composi tion at depth is improved.

[0054] According to certain embodiments of a process according to the invention, at least one ap plicator roller is rotated in a direction of rotation chosen so that the peripheral ends of the filiform elements are moved countercurrent to the movement of the paper web.

[0055] According to certain other embodiments of a process according to the invention, at least one applicator roller is rotated in a direction of rotation chosen so that the peripheral ends of the filiform elements are moved concurrently with respect to the movement of the paper web.

[0056] According to certain embodiments of a process according to the invention, a withdrawal of fatty acid chloride(s) - in particular excess fatty acid chloride(s) - on the paper web is car ried out by means of a recovery device having a rotatable recovery surface provided with filiform elements which are not reactive with said reactive composition and are able to: - be loaded with fatty acid chloride(s) by contact of the recovery surface and the paper web, and - release fatty acid chloride(s) by application of a flow of gaseous composition heated to a temperature above said acylation temperature - in particular to a temperature between said acylation temperature and the vaporization temperature of each fatty acid chloride of said reactive composition.

[0057] According to certain embodiments, the flow of gaseous composition is applied in contact with the recovery surface of the recovery device and/or in contact with the moving paper web.

[0058] An acylated solid material, in particular paper web, which is substantially free of residual fatty acid chloride(s) and hydrochloric acid is formed. The flow of gaseous composition is applied in contact with the paper web and countercurrent with respect to the run direction of the paper web so as to entrain at least one portion of hydrochloric acid in the gaseous state formed by the acylation.

[0059] According to the invention, said reactive composition is free of any solvent medium (with the exception of possible traces), in particular of any nonpolar solvent medium distinct from the fatty acid chloride(s).

[0060] The invention also relates to an acylated solid material capable of being obtained by a pro cess according to the invention. The invention also relates to an acylated solid material ob tained by a process according to the invention.

[0061] The invention also relates to a process for the chromatogenic acylation of a solid material bearing hydroxyl groups that are accessible to at least one fatty acid chloride in the gaseous state and that are capable of reacting with this (these) fatty acid chloride(s) in the gaseous state, characterized in combination with all or some of the features mentioned above or be low. Whatever formal presentation is given of them, unless explicitly stated otherwise, the various features mentioned above or below should not be considered to be intimately or inextricably linked to one another, it being possible for the invention to relate to only one of these structural or functional features, or only some of these structural or functional fea tures, or only a part of one of these structural or functional features, or indeed any group ing, combination or juxtaposition of all or some of these structural or functional features.

[0062] Other objectives, features and advantages of the invention will become apparent on reading the following description which refers to the appended figures and to the examples given solely by way of non-limiting example of the invention, and in which:

[0063] [Fig 1] figure 1 is an overview diagram illustrating a chromatogenic acylation process known from the prior art (W02022/033698) and presented solely by way of comparison with a process according to the invention,

[0064] [Fig 2] figure 2 is an overview diagram illustrating afirst embodiment of a chromatogenic acylation process according to the invention,

[0065] [Fig 3] figure 3 is an overview diagram illustrating a second embodiment of a chromato genic acylation process according to the invention, and

[0066] [Fig. 4] figure 4 is a schematic representation of a device for implementing an industrial process for the chromatogenic acylation of a width of paper according to the invention.

[0067] The process known from W02012/066015, for the chromatographic acylation of a paper material comprising the deposition on the paper material of liquid fatty acid chloride by means of a cylinder, referred to as an anilox roll, designed for printing is not satisfactory. The paper material obtained by such a known process contains a significant residual amount of free fatty acid chloride, despite the implementation of a final blowing (or" flushing ") step. Residual fatty acid chloride can decompose by hydrolysis to free fatty acid and hydrochloric acid which can degrade the solid material. In addition, the free fatty acids formed alter the barrier properties of the solid material and the residual fatty acid chlorides pose a toxicity problem for applications in particular in the field of food packaging and in the biomedical field.

[0068] A process for the chromatogenic acylation of a tissue is also known from W02022/033698. According to this known process, stearic acid chloride is deposited by means of a varnish roller impregnated with stearic acid chloride at room temperature, on one of the faces of the tissue brought to a temperature of 160°C. The amount of stearic acid chloride impreg nated on the varnish roller and the amount deposited on the tissue are adjusted by succes sive applications, without reloading the roller, and depletion of the stearic acid chloride un til the optimum amount of acid chloride impregnated on the roller is obtained. The tissue, having received the optimal amount of stearic acid chloride, is then placed in an oven at a temperature of 160°C. Such a known process cannot be applied as is on an industrial scale.

[0069] The known chromatogenic acylation process described above is illustrated in figure 1. Such a known process comprises a step 2' of heating a paper material 1' in an oven heated to a temperature, referred to as the acylation temperature, below the vaporization tempera ture of the fatty acid chloride, but sufficient to allow acylation of the paper material 1'by reaction of a fatty acid chloride 5' in the gaseous state with reactogenic hydroxyls of the paper material 1'. In this known process, a hot paper material 6' is formed at said acylation temperature. At the same time, a varnish roller 3' having an application surface formed of a pile 4' is impregnated by rolling 7' in acid chloride 5' in the liquid state at atmospheric temperature under rolling conditions suitable for obtaining a varnish roller 8' in an optimal state of impregnation allowing a deposition of an optimal amount of stearic acid chloride 5' in the liquid state. In this known process, a step 9' of applying stearic acid chloride 5' in the liquid state and at atmospheric temperature to the hot paper material 6' is carried out by rolling the impregnated varnish roller 8' over the hot paper material 6', allowing an acyla tion of the hot paper material 6' by stearic acid chloride in the gaseous state, at a tempera ture inevitably below said acylation temperature and the formation of an acylated and hy drophobic material 10'. According to this known process, stearic acid chloride at room temperature and essentially in liquid form is deposited on a paper material heated to a tem perature sufficient to enable chromatographic acylation of the paper material by stearic acid chloride in the gaseous state which is formed due to the the temperature of the paper material.

[0070] An overview diagram of a process according to the invention for the chromatogenic acyla tion of a solid material 1 bearing hydroxyl groups that are accessible to at least one fatty acid chloride in the gaseous state and that are capable of reacting with this (these) fatty acid chloride(s) is represented in figure 2.

[0071] The hydroxylated solid material 1 may be a cellulosic material. The solid material 1 may also be formed of a fabric, in particular a fabric comprising cotton fibers. The solid mate rial 1 may be a paper material 1. That being said, any type of hydroxylated solid material can be used. The hydroxylated solid material 1 may have an uneven surface finish. It may have a high roughness. However, the hydroxylated solid material 1 may also be a material in particular a calendered paper - having an even surface finish of low roughness. The hy droxylated solid material 1 may be porous or nonporous. The hydroxylated solid material 1 may be a nonporous material having hydroxyl groups borne by a polymer - in particular PVA (polyvinyl alcohol) - forming the free surface of the hydroxylated solid material. The hydroxylated solid material 1 may be a paper material rendered nonporous and impermea ble to air by surface application of a layer of PVA, as described in FR2925910. The hy droxylated solid material 1 may be a disposable paper tissue formed of a plurality of cellu losic sheets with a grammage of less than 30 g/m2 - in particular less than 20 g/m 2 , prefer ably between 10 g/m2 and 30 g/m2 , more preferentially between 10 g/m2 and 20 g/m2 . The paper material may be formed of crosslinked cellulose fibers, the rotational mobility of which is restricted, giving the paper material improved properties in terms of mechanical strength in general and wet strength in particular. The cellulose fibers are then bonded to gether by hydrogen bonds and by covalent bonds formed with at least one group of cross linking atoms, such as, for example, a 1-chloro-2,3-epoxypropane or epichlorohydrin de rivative. The hydroxylated solid material 1 may be a flexible material, i.e. it is deformable under the effect of its own weight. The hydroxylated solid material 1 may be a paper mate rial in the form of a sheet of paper known as "paper towel", toilet paper, a paper napkin or a filter paper. The hydroxylated solid material 1may be a board. It can be rigid, that is, it does not deform significantly under the effect of its own weight. The hydroxylated solid material 1 may be a piece of corrugated board formed from at least one sheet of fluted pa per and at least one board sheet with a grammage of greater than 160 g/m2

.

[0072] In the process according to the invention shown in figure 2, an applicator device 3 is cho sen having an application surface provided with filiform elements 4 which are not reactive with the fatty acid chlorides of a composition, referred to as a reactive composition 20, of at least one fatty acid chloride. Such an applicator device 3 is chosen which is suitable for being able to be subjected to a temperature of between 160°C and 250°C without loss of its adsorbent and application functionalities. It may, for example, be an applicator device 3, the applicator face of which is formed offiliform elements 4 of inorganic fibers or microfi bers, such as glass fibers or microfibers or carbon fibers or microfibers, or filiform ele ments 4 of aramid fibers or microfibers, such as aramid fibers or microfibers known under the Kevlar@ trademark. The applicator device 3 may be an applicator roller, an applicator pad, or an applicator brush provided with the filiform elements 4. The applicator device 3 may have an application surface formed of oleophilic filiform elements 4 (having affinity for fatty substances). Any suitable type of oleophilic material can be used. However, the applicator device 3 may have an application surface formed of oleophobic filiform ele ments 4. In particular, they may be filiform elements 4 coated with a perfluorinated coat ing, in particular a Teflon@ coating. The application surface of the applicator device 3 is formed of a chemically stable material that is resistant to abrasion and temperature, partic ularly to said acylation temperature. Preferably, the filiform elements have a free end suita ble for cooperating with the surface of the hydroxylated solid material by brushing. The applicator device 3 may be a roller, in particular a roller of the "varnish roller" type and that is suitable for withstanding said acylation temperature, without loss of its adsorbent and application properties. The filiform elements 4 are flexible and suitable for being loaded with fatty acid chloride(s) and for releasing at least one portion of the loaded fatty acid chloride(s), in particular by elastic deformation. The filiform elements 4 may have a length of between 1 mm and 100 mm or more. The filiform elements may have a trans verse cross section with a diameter of between 1 m and 1000 im. The applicator device may be a varnish roller, the application surface of which is formed of a pile provided with filiform elements having an implantation density of greater than 10 filiform elements per mm2 of application surface, in particular of between 50 and 500 filiform elements per mm2 of application surface. The filiform elements are chosen so as to exhibit, in particular dur ing rotation of the applicator roller, a rigidity imparted by the rotation of the applicator roller, which rigidity is sufficient to allow application of fatty acid chloride(s) over at least one portion of the thickness of the hydroxylated solid material, without damaging it. The filiform elements have a flexibility chosen so as not to damage the hydroxylated solid ma terial, by contact.

[0073] In a process according to the invention, a composition, referred to as reactive composition 20, of at least one fatty acid chloride is chosen or prepared. At least one fatty acid chloride is chosen from the group formed of fatty acid chlorides of formula R-CO-Cf in which R is a hydrocarbon chain having a number of carbon atoms of between 13 (limit included) and 29 (limit included), in particular between 15 (limit included) and 29 (limit included). At least one fatty acid chloride is chosen from the group formed of palmitic acid chloride (C 16 ), stearic acid chloride (C 1 8), arachidic acid chloride (C2 0) and behenic acid chloride (C 2 2 ). At least one fatty acid chloride is behenic acid chloride (C 2 2 H 4 3 0C), the vaporiza tion temperature of which at atmospheric pressure is of the order of 385°C. At least one fatty acid chloride is palmitic acid chloride (C16 H3 1 0C), the vaporization temperature of which at atmospheric pressure is of the order of 330°C. At least one fatty acid chloride is stearic acid chloride C 1 8 H 3 5 0C), the vaporization temperature of which at atmospheric pressure is of the order of 350°C. Nothing prevents the use of a fatty acid chloride which can be prepared by transchlorination of a fatty acid with a transchlorinating agent such as, for example, acetyl chloride. The fatty acid chlorides chosen for the implementation of a process according to the invention are liquid at room temperature. In a process according to the invention, the filiform elements 4 of the applicator device 3 are impregnated 5 with at least one liquid fatty acid chloride. This impregnation step 5 is carried out by bringing the filiform elements 4 into contact with said reactive composition 20 at room temperature, that is to say at a temperature reached without using means for regulating this temperature. However, there is nothing to prevent the filiform elements 4 from being, during this im pregnation 5, at a temperature above room temperature but also inevitably below or at most equal to said acylation temperature. The temperature of the filiform elements 4 is suitable for enabling them to be loaded with said reactive composition 20 essentially in the liquid state. There is nothing to prevent said reactive composition 20 from being brought, during this impregnation step 5, to a temperature above room temperature, but adapted, depending on the fatty acid chloride(s) used, so that the fatty acid chloride(s) used are essentially in liquid form and capable of being impregnated in the liquid state on the filiform elements 4 of the applicator device 3. An applicator device 6 impregnated and loaded with said liquid reactive composition 20 is formed at the end of this impregnation step 5.

[0074] In a process according to the invention, a step 7 of heating said reactive composition 20 impregnated on the filiform elements 4 of the applicator device 3 is carried out and is adapted so that said reactive composition 20 reaches said acylation temperature. This heat ing 7 is carried out by any appropriate means. These means may be radiative heating means (for example by radiation in the infrared range), inductive heating means, or con vective heating means. These means may also be heating means specific to the applicator device 3 and suitable for heating at least the filiform elements 4 and said reactive composi tion 20. At the end of this heating step 7, an applicator device 3 provided with filiform ele ments 8 loaded with said reactive composition 20 brought to said acylation temperature is formed.

[0075] In a process according to the invention, a step 9 of heating the solid material 1 is carried out so as to form a hot hydroxylated solid material 10 -in particular that is at said acylation temperature-, prior to a step 11 of applying the filiform elements 8 loaded with, and retain ing, said reactive composition 20. The application step 11 is carried out by rolling the ap plicator device 3 over the hydroxylated solid material 1. Advantageously, the hot hydrox ylated solid material 10 is at least partially dehydrated as a result of this heating 9. Moreo ver, the fact that the hot hydroxylated solid material 10 is at said acylation temperature makes it possible to help to maintain said reactive composition 20 at said acylation temper ature, to promote chromatogenic acylation and to form the acylated solid material 12.

[0076] Surprisingly, the inventor has observed that heating 7 of said reactive composition 20 ad sorbed by impregnation in the filiform elements 4 of the applicator device 3 allows appli cation of fatty acid chloride on the hydroxylated solid material 1 and acylation of this hy droxylated solid material 1 with acid chloride in the gaseous state. According to the inven tion, the application of said reactive composition 20 heated to said acylation temperature of between 160°C and 250°C does not lead to a loss of fatty acid chloride in the gaseous state by dissipation into the atmosphere surrounding the filiform elements 4, 8. On the contrary, the filiform elements 4, 8 seem to behave like a reservoir of fatty acid chloride - in particu lar in the gaseous state - making it possible to release/form fatty acid chloride in the gase ous state in contact with the hydroxylated solid material 1 and to acylate it.

[0077] The invention goes against the teaching provided by the prior art, which describes distrib uting the fatty acid chloride(s) in a preferentially liquid state and necessarily at low temper ature in contact with the cold or hot solid material, then heating the cold hydroxylated solid material to said acylation temperature or maintaining the hot hydroxylated solid material at said acylation temperature. According to this teaching, the fatty acid chloride(s) essentially in the liquid state deposited in contact with the hydroxylated solid material constitute(s) a reservoir of fatty acid chloride(s) essentially in the liquid state placed in contact with the hydroxylated solid material. According to this teaching, fatty acid chloride(s) in the gase ous state is (are) formed in the vicinity of the accessible hydroxyls of the hydroxylated solid material, due to heating the hydroxylated solid material to said acylation temperature. According to this teaching, the formation of fatty acid chloride(s) in the gaseous state in the vicinity of the accessible hydroxyls of the hydroxylated solid material makes it possible to overcome the disadvantages of said boundary layer. That being said, the teaching pro vided by the prior art does not make it possible to solve the problem of the persistence on the hydroxylated solid material of amounts of fatty acid chloride(s) in the liquid state which have not been heated for a long enough time to be vaporized and to be able to react in the gaseous state with the hydroxylated solid material, in particular due to the movement of the web of hydroxylated solid material.

[0078] Of course, there is nothing to prevent, in a variant (not shown) of a chromatogenic acyla tion process according to the invention implemented on an industrial scale, the hydrox ylated solid material from being in the form of a web of paper wound in a roll on itself, the paper being moved between an upstream reel and a downstream device for rewinding a web of acylated paper. In such a process implemented on an industrial scale, the paper has a run speed of between 30 and 100 meters per minute. An example of a device suitable for implementing such a process is shown in figure 4. In such a process, said reactive compo sition is applied at a fixed station to at least one main face of the moving paper web. In such a process, the applicator device comprises an applicator roller having an application surface provided with filiform elements and arranged over the entire width (or reel width) of the paper web. The roller has an axis of rotation parallel to the plane in which the paper web runs and not parallel - in particular orthogonal - to the run direction of this web. The roller is placed vertically at a distance from the paper web so that the filiform elements lightly contact the moving paper web without damaging it. Advantageously, the roller may be of the type having an axial lumen for receiving said reactive composition and for dis pensing said reactive composition, assisted by centrifugal force, conveyed along the fili form elements until it is brought into contact with the paper web.

[0079] In certain advantageous embodiments, the roller is provided with means for heating said reactive composition to said acylation temperature. In these advantageous embodiments, the filiform elements forming the application surface of the roller act as an applicator reser voir for fatty acid chloride(s) in the gaseous state at said acylation temperature. In these ad- vantageous embodiments, the volume in which the fatty acid chloride(s) are at the satura tion vapor pressure at said acylation temperature is limited to the free volume provided by the filiform elements of the roller heated to said acylation temperature. According to these advantageous embodiments, it is not necessary to provide a thermostatically controlled chamber at said acylation temperature in which the partial pressure of the fatty acid chlo ride(s) is maintained at the saturation vapor pressure throughout its entire volume. That be ing said, nothing prevents the provision of at least one fairing wall of the applicator roller(s) and for confining the fatty acid chloride(s) in the gaseous state in contact with the paper web.

[0080] In certain advantageous embodiments of a chromatogenic acylation process according to the invention implemented on an industrial scale, when the roller has an axial lumen for receiving said reactive composition and for centrifugal dispensing of said reactive compo sition guided along the filiform elements until it comes into contact with the paper web, the roller, in particular the heating roller, is supplied with fatty acid chloride by a provision of said reactive composition in the axial lumen of the roller. In these embodiments, the im pregnation of the filiform elements is at least partly carried out by the centrifugal stress produced due to the rotation of the roller, to which said reactive composition is subjected in the applicator roller.

[0081] In other embodiments, the applicator device may include, in addition to the roller, a device for dispensing fatty acid chloride onto the roller. It may be a cylinder, known as an anilox roller, for supplying the roller by kissing the surface of said anilox roller with the filiform elements. Any type of anilox roller can be used. It can be used by adapting the dimensions of its cells and their surface density to the amount of fatty acid chloride to be deposited on the applicator roller. The anilox roller may have an angular speed of rotation identical to or different from the speed of rotation of the applicator roll. Said anilox roller may be sup plied with liquid fatty acid chloride via a doctor blade chamber itself supplied, in particular continuously, with fatty acid chloride.

[0082] The roller may be rotated with an angular speed of rotation chosen so that the free ends of the filiform elements are rotated with a linear speed having a value different from the value of the run speed of the paper web. The linear speed of the free ends of the filiform elements and the run speed of the paper web are not necessarily identical and can be adjusted to pro duce the desired light contact. That being said, the roller can be rotated in a direction of ro tation chosen so that the free ends of the filiform elements of the pile are moved counter currently or concurrently with respect to the movement of the paper web.

[0083] In a chromatogenic acylation process according to the invention implemented on an indus trial scale, nothing prevents the roller and the dispensing device from being placed in a thermoregulated enclosure maintained at said acylation temperature.

[0084] In an advantageous variant, not shown, of a chromatogenic acylation process according to the invention implemented on an industrial scale, a flow of gaseous composition able to be loaded with hydrochloric acid in contact with the paper web being acylated is formed so as to move the hydrochloric acid formed as a result of this acylation away from the paper web.

[0085] An overview diagram of a variant of a process according to the invention for the chromato genic acylation of a solid material 1, 2 bearing hydroxyl groups that are accessible to at least one fatty acid chloride in the gaseous state and that are capable of reacting with this (these) fatty acid chloride(s) is represented in figure 3. In this variant shown, a plurality of acylation phases 40, 50, 60 of a solid material 1, 2 are carried out, each of the phases 40, 50, 60 comprising a step 11, 24, 34 of applying a reactive composition 20, 21, 22 on the solid material 1, 2. The phases 40, 50, 60 of this plurality of phases can be carried out in an artisanal manner successively on the same piece of a solid material 1, in particular of a pa per material. However, the phases 40, 50, 60 of this plurality of phases can be carried out during an industrial process for the chromatogenic acylation of a paper web 2 moved be tween an upstream reel of the paper web 2 and a downstream device 36 for rewinding the web 12, 25, 35 of acylated paper. During this implementation on an industrial scale, each reactive composition 20, 21, 22 is applied by means of an applicator device 3, 15, 28 for applying reactive composition(s) 20, 21, 22 respectively. The applicator devices 3, 15, 28 are arranged at a distance from one another along a run zone of the paper web 2, 12, 25, 35, extending in the thermoregulated chamber 39. Each reactive composition 20, 21, 22 may be formed of a single fatty acid chloride or may comprise a plurality of fatty acid chlorides. Advantageously, each reactive composition is free of any organic solvent. The reactive compositions 20, 21, 22 may comprise the same fatty acid chloride or chlorides of different fatty acids and of different fatty chain lengths.

[0086] The overview diagram represented in figure 3 also illustrates a process according to the in vention implemented on an industrial scale, for the chromatogenic acylation of a web 2 of paper material 1 moved between an upstream reel and a downstream device for rewinding a web of acylated paper. In this industrial process, the paper web 2 is moved by any means known to those skilled in the art, so that the paper of the paper web 2 passes successively, owing to this movement, through a plurality of successive treatment zones. A first phase 40 of acylation of the paper of the paper web 2 is carried out in an upstream zone (with re spect to the run direction from upstream to downstream of the paper web) of the plurality of successive treatment zones, then a second acylation phase 50 is carried out in an inter mediate zone of this plurality of successive zones, then a third acylation phase 60 is carried out in a downstream zone of this plurality of successive zones. For example, nothing pre vents the first acylation phase 40 from being carried out at an acylation temperature TI, the second acylation phase 50 from being carried out at an acylation temperature T2 and the third acylation phase 60 from being carried out at an acylation temperature T3, where TI < T2 < T3.

[0087] During the first phase 40, the applicator device 3 has an application surface formed offili form elements 4 that are not reactive with the fatty acid chlorides of said reactive composi tion 20. The applicator device 3 and the filiform elements 4 are suitable for being placed, without deterioration, at a temperature of between 160°C and 250°C and without loss of their application functions. In a process according to the invention carried out on an indus trial scale, the applicator device 3 may be a roller arranged so that its axis of rotation on itself extends in a plane parallel to the plane of the moving paper web 2 and not parallel in particular orthogonal - to the run direction of this paper web 2. The applicator device 3 is chosen and arranged so as not to damage the paper of the moving paper web 2. During the first phase 40, the filiform elements 4 of the applicator device 3 are impregnated 5 with at least one liquid fatty acid chloride. This impregnation step 5 is carried out at low temper ature (i.e. at a temperature below the envisaged acylation temperature) by bringing the fili form elements 4 forming the application surface of the applicator device 3 into contact with said reactive composition 20 at room temperature, that is to say at a temperature reached without using means for regulating this temperature. However, there is nothing to prevent the filiform elements 4 from being brought, during this impregnation 5, to a tem perature above room temperature but also inevitably below or at most equal to said acyla tion temperature. There is nothing to prevent said reactive composition 20 itself from being brought, during this impregnation step 5, to a temperature above room temperature, but adapted, depending on the fatty acid chloride(s) used, so that the fatty acid chloride(s) used are essentially in liquid form and able to be loaded in the liquid state on the filiform ele ments 4 of the applicator device 3. An applicator device 6 loaded with said liquid reactive composition 20 is obtained at the end of this impregnation step 5.

[0088] In a process according to the invention, a step 7 of heating said reactive composition 20 ad sorbed on the filiform elements 4 of the applicator device 3 is carried out, this heating step 7 being adapted so that said reactive composition 20 reaches an acylation temperature TI.

This heating 7 is carried out by any appropriate means. At the end of this heating step 7, an applicator device 3 provided with filiform elements 8 loaded with said reactive composi tion 20 at said acylation temperature Ti is formed.

[0089] In a process according to the invention, a step 9 of heating the paper of the moving paper web 2 is carried out so as to form a hot paper 10 at said acylation temperature T1, prior to a step 11 of applying the hot filiform elements 8 retaining said reactive composition 20, by rolling the applicator device 3 over the hot paper 10 of the paper web 2. Moreover, the fact that the hot paper 10 is at said acylation temperature Ti makes it possible to help to main tain said reactive composition 20 at said acylation temperature TI, to promote chromato genic acylation and to form the acylated solid material 12.

[0090] During a second chromatogenic acylation phase 50, use is made of an applicator device 15 having an application surface formed of filiform elements 16 that are not reactive with the fatty acid chlorides of a second reactive composition 21. The applicator device 15 and the filiform elements 16 are suitable for being placed, without deterioration, at a temperature of between 160°C and 250°C and without loss of the application functions. In a process ac cording to the invention carried out on an industrial scale, the applicator device 15 may be a roller with an axis of rotation extending in a plane parallel to the plane of the moving pa per web 2 and not parallel - in particular orthogonal - to the run direction of the paper. The applicator device 15 is chosen and arranged so as not to damage the moving paper 1, 2, 14. During the second phase 50, the filiform elements 16 of the applicator device 15 are im pregnated 17 with at least one liquid fatty acid chloride. This impregnation 17 is carried out at a temperature below the envisaged acylation temperature T2, by bringing the fili form elements 16 into contact with said reactive composition 21 at room temperature, that is to say at a temperature reached without using means for regulating this temperature. However, there is nothing to prevent the filiform elements 16 from being, during this im pregnation 17, at a temperature above room temperature. That being said, the filiform ele ments 16 are at a temperature necessarily below or at most equal to said acylation tempera ture T2. There is nothing to prevent said reactive composition 21 from being brought, dur ing this impregnation step 17, to a temperature above room temperature, but adapted, de pending on the fatty acid chloride(s) used, so that the fatty acid chloride(s) used are essen tially in liquid form and able to be loaded in the liquid state on the filiform elements 16. An applicator device 18 loaded with said liquid reactive composition 21 is formed at the end of this impregnation step 17. A step 19 of heating said reactive composition 21 adsorbed on the filiform elements 16 of the applicator device 15 is then carried out and is adapted so that said reactive composition 21 reaches the acylation temperature T2. This heating 19 is carried out by any appropriate means. At the end of this heating step 19, an applicator de vice 3, the filiform elements 23 of which loaded with said reactive composition 21 are brought to said acylation temperature T2, is formed.

[0091] A step 13 of heating the paper of the moving paper web 12 is carried out so as to form a hot paper 14 at said acylation temperature T2, prior to a step 24 of applying said reactive composition 21 on the hot paper 14, by rolling the applicator device 15 over the paper 14 and contacting the filiform elements 23 on the hot paper 14. Moreover, the fact that the pa per 14 is at said acylation temperature T2 makes it possible to help to maintain said reac tive composition 21 at said acylation temperature T2, to promote the chromatogenic acyla tion and to form an acylated paper 25 bearing acyl groups of thefirst and second reactive compositions 20, 21.

[0092] In the embodiment shown, use is made, during a third phase 60, of an applicator device 28 having an application surface formed of filiform elements 29 that are not reactive with the fatty acid chlorides of a reactive composition 22. The applicator device 28 and the filiform elements 29 are suitable for being placed, without deterioration, at a temperature T3 of be tween 160°C and 250°C and without loss of the application functions. In a process accord ing to the invention carried out on an industrial scale, the applicator device 28 is preferably an applicator roller 28 with an axis of rotation on itself extending in a plane parallel to the plane of the paper of the moving paper web 25, 2 and not parallel - in particular orthogonal - to the run direction of the paper. The applicator device 28 is chosen and arranged so as not to damage the paper of the moving web 2, 25. During the second acylation phase 60, the filiform elements 29 are impregnated 30 with at least one liquid fatty acid chloride. This impregnation 30 is carried out at a temperature below an envisaged acylation temper ature T3, by bringing the filiform elements 29 of the applicator device 28 into contact with said reactive composition 22 at room temperature, that is to say at a temperature reached without using means for regulating this temperature. However, there is nothing to prevent the filiform elements 29 from being, during this impregnation 30, at a temperature above room temperature but also preferably below said acylation temperature T3. There is noth ing to prevent said reactive composition 22 from being brought, during this impregnation step 30, to a temperature above room temperature, but adapted, depending on the fatty acid chloride(s) used, so that the fatty acid chloride(s) used are essentially in liquid form and able to be loaded by adsorption in the liquid state on the filiform elements 29 of the appli cator device 28. An applicator device 31 loaded with said liquid reactive composition 22 is formed at the end of this impregnation step 30. A step 32 of heating said reactive composi tion 22 adsorbed on/impregnated in the filiform elements 29 of the applicator device 28 is then carried out and is adapted so that said reactive composition 22 reaches the acylation temperature T3. This heating 32 is carried out by any appropriate means. At the end of this heating step 32, filiform elements 33 loaded by impregnation with said reactive composi tion 22 brought to said acylation temperature T3 is formed.

[0093] A step 26 of heating the paper of the moving paper web 2, 25 is carried out so as to form a hot paper 27 at said acylation temperature T3, prior to a step 34 of applying the filiform elements 33 of the applicator device 28 retaining said reactive composition 22, by rolling the applicator device 28 over the paper 27. Moreover, the fact that the paper 27 is at said acylation temperature T3 makes it possible to help to maintain said reactive composition 22 at said acylation temperature T3, to promote the chromatogenic acylation and to form an acylated solid material 35 bearing acyl groups of the first, second and third reactive compositions 20, 21, 22. Provision may be made for other subsequent acylation phases.

[0094] In an embodiment that is not shown, there is nothing to prevent the implementation of a final phase of extracting fatty acid chloride that may be present in excess on the running paper web. To do this, a recovery device comprising an extractor roller, in particular a var nish roller having a recovery surface formed of a pile, can be applied to the paper web to take back off fatty acid chloride in the liquid state from the paper.

[0095] An example of an acylation device 100 capable of being used for implementing a process according to the invention is shown in figure 4. The acylation device 100 comprises an up stream reel 66 of a web 2 of paper to be acylated and a downstream device 36 for rewind ing a web 35 of acylated paper. The acylation device 100 is provided with means 37 for guiding the web 2 of paper moving between the upstream reel 66 and the downstream roll 36. The guide means 37 comprise a plurality of rollers for guiding the moving paper web 2,10,12, 25, 35, which are positioned so as to guide the paper web 2,10,12, 25, 35 moving through a thermoregulated chamber 39 of the acylation device 100. The thermoregulated and, where appropriate, compartmentalized chamber 39 has a first upstream zone 41 (up stream in terms of the run direction 42 of the web 2 of paper 1) for entry of the paper 1 of the web into the first upstream zone 41 and into the thermoregulated chamber 39. This first upstream zone 41 is provided with at least one heated roller 38 and means for guiding the paper web 2, suitable for heating the paper web 2 to a temperature enabling the dehydra tion thereof, at least partially, while it is moving and prior to the acylation thereof. The thermoregulated chamber 39 has, extending downstream of the first upstream heating zone 41, a first acylation zone 43 suitable for being passed through by the moving paper web 2. The first acylation zone 43 may be provided with means (not shown) for heating and/or maintaining the atmosphere of this first acylation zone 43 at a chromatogenic acylation temperature TI. It also comprises a device 45 for dispensing a reactive composition 20 of at least one, in particular only one - fatty acid chloride on the surface of the paper web 2. The dispensing device 45 comprises a support roller 44 and an applicator roller 3 having an application surface formed of filiform elements 4, in particular filiform elements 4 that form a pile. The applicator roller 3 is suitable for being rotated on itself so that the filiform elements 4 sweep, with light contact, the surface of the moving paper web 2,10. The sup port roller 44 and the filiform elements 4 of the applicator roller 3 cooperate to guide the paper web 2,10 into contact with the filiform elements 4 of the applicator roller 3.

[0096] The thermoregulated chamber 39 has, extending downstream of the first acylation zone 43, a second acylation zone 48 suitable for being passed through by the web 2 of moving paper 12 treated in the first acylation zone 43. The second acylation zone 48 may be provided with means (not shown) for heating and/or maintaining the atmosphere of this second acyl ation zone 48 at a chromatogenic acylation temperature T2. It also comprises a device 51 for dispensing a reactive composition 21 of at least one, in particular only one - fatty acid chloride. The dispensing device 51 comprises a support roller 49, an applicator roller 15 having an application surface formed offiliform elements 16, in particular filiform ele ments 16 that form a pile, and that is suitable for being rotated so that the filiform elements 16 sweep, with light contact, the surface of the web 2 of moving paper 12. The support roller 49 and the applicator roller 15 cooperate to guide the web 2 of paper 12 by applying it in contact with the filiform elements 16 of the applicator roller 15.

[0097] The thermoregulated chamber 39 has, extending downstream of the second acylation zone 48, a third acylation zone 54 suitable for being passed through by the moving paper web 2 treated in the second acylation zone 48. The third acylation zone 54 may be provided with means (not shown) for heating and/or maintaining the atmosphere of this third acylation zone 54 at a chromatogenic acylation temperature T3. It also comprises a device 56 for dis pensing a reactive composition 22 of at least one, in particular only one - fatty acid chlo ride. The dispensing device 56 comprises a support roller 55 and an applicator roller 28 having an application surface formed offiliform elements 29, in particular filiform ele ments 29 that form a pile, and that is suitable for being rotated so that the filiform elements 29 sweep, with light contact, the surface of the web 2 of moving paper. The support roller 55 and the applicator roller 28 cooperate to guide the paper web 2 by applying one of the faces of the paper web 2 in contact with the applicator roller 28.

[0098] In certain advantageous embodiments, at least one - notably each - applicator roller 3, 15, 28 is provided with means for heating said corresponding reactive composition 20, 21, 22 to the acylation temperature TI, T2, T3. In these embodiments, the first, second and third acylation zones 43, 48, 54 of the thermoregulated and/or compartmentalized chamber 39 are not necessarily each heated to said corresponding acylation temperature TI, T2, T3. In addition, at least one, in particular each, of the applicator rollers 3, 15, 28 advantageously has an axial lumen for centrifugally supplying, in particular continuously, the filiform ele ments 4, 16, 29 with reactive compositions 20, 21, 22.

[0099] There is also nothing to prevent at least one - in particular each - of the support rollers 44, 49, 55 from being a heated roller suitable for helping to heat the paper web 2 to said acyla tion temperature.

[0100] In certain other embodiments, not shown, at least one - in particular each - of the dispens ing devices 45, 51, 56 may comprise a cylinder, known as an anilox roller, for supplying the applicator roller 3, 15, 28 with a reactive composition 20, 21, 22. Said anilox roller is arranged so as to be able to be lightly contacted tangentially by the corresponding applica tor rollerer 3, 15, 28. In these embodiments, the temperature of said anilox roller and of the reactive composition 20,21,22 presented by said corresponding anilox roller are substan tially the same temperature as the applicator roller 3, 15, 28. Said anilox roller may be sup plied with liquid fatty acid chloride by means of a doctor blade chamber itself supplied, in particular continuously, with fatty acid chloride. In these embodiments, the doctor blade chamber forms a wall covering said anilox roller facing the peripheral surface thereof, with the exception of an open strip allowing contact of said anilox roller with the applicator roller 3, 15, 28.

[0101] The thermoregulated chamber 39 has, extending downstream of the third acylation zone 54, a zone 59 for extraction and back exchange of fatty acid chloride which may be present in excess on the moving paper web. The extraction zone 59 is provided with a support roller 61 arranged to be able to cooperate with an extractor roller 62 having a recovery sur face formed of filiform elements 63 and to guide the running paper web 35. The recovery surface of the extractor roller 62 may be a pile provided with filiform elements 63 able to be loaded with excess fatty acid chloride(s) on the surface of the paper web 35. Advanta geously, a flow 64 of gaseous composition - in particular a flow of atmospheric air - heated to a temperature above said acylation temperature - in particular between said acylation temperature and the vaporization temperature of at least one - in particular each - fatty acid chloride of said reactive composition, is applied in contact with the paper web 2 so as to entrain residual fatty acid chloride, vaporized under the effect of the flow 64 of gaseous composition. The flow 64 of gaseous composition loaded with fatty acid chloride is en trained successively through acylation zones 54, 48, 43, countercurrent -from downstream to upstream- to the run direction of the paper web 2 and also enables an entrainment of the gaseous hydrochloric acid formed due to the acylation reaction in the thermoregulated chamber 39.

[0102] In certain embodiments, the extractor roller 62 is heated to a temperature, notably to a tem perature between 250°C and 400°C, which promotes the vaporization of fatty acid chlo ride(s). In other embodiments, the flow of gaseous composition heated to the vaporization temperature is applied over the filiform elements of the extractor roller.

[0103] In certain embodiments, the gaseous atmosphere of the thermoregulated and/or compart mentalized chamber 39 and/or the gaseous atmosphere extending into the lumen of at least one applicator roller 3, 15, 28 is depleted in gaseous oxygen. In these embodiments, a flow of at least one inert gas is introduced into the thermoregulated and/or compartmentalized chamber 39 and/or into the gaseous atmosphere extending into the lumen of at least one applicator roller 3, 15, 28.

[0104] EXAMPLE 1- Application conditions An applicator device is made using glass microfibers bonded together to form an applicator brush or pad. The glass microfibers are chosen to withstand temperatures of between 160°C and 250°C. They are advantageously inert with respect to the fatty acid chlorides used. The applicator brush is loaded by briefly contacting the applicator brush with a piece of microfiber fabric with a size of 100 mm x 100 mm impregnated with 4 ml of undiluted liquid fatty acid chloride. It has been shown that this qualitative approach makes it possible to deposit on a solid material by contact of the brush on the solid material maintained for a fraction of seconds, the minimum amount of fatty acid chloride for conferring a hydropho bicity of the treated paper material which is acceptable after development of the acylation reaction.

[0105] The applicator brush thus loaded with fatty acid chloride is used to apply fatty acid chlo ride to a hydroxylated solid material. The applicator brush can be applied to the paper ma terial with a contact time of the tip of the applicator brush and the hydroxylated solid mate rial of the order of magnitude of 1 / 1 0 th of a second and so that the tip of the microfiber brush deforms on contact, generating intimate physical contact between the microfibers of the brush and the surface of the paper material, promoting the transfer of fatty acid chlo ride.

[0106] That being said, it is possible to apply the fatty acid chloride by gliding the tip of the appli cator brush over the surface of the paper material, like a paint. The application of fatty acid chloride by means of a brush made in this way makes it possible to mimic an application of fatty acid chloride on a moving paper such as can be carried out by means of a varnish roller provided with filiform elements, by favoring an instant application of reagent rather than a continuous application.

[0107] EXAMPLE 2 - Application conditions - Variable temperature of the applicator brush - Pa per material at room temperature Example 2 describes the application of a fatty acid chloride by means of an applicator brush that applies hot acid chloride to a paper material at room temperature. Palmitic acid chloride (C 1 H3 1 -CO-C) or stearic acid chloride (C 17 H3 5 -CO-C) is applied to a piece of blotting paper (Canson, 125 g/m2 ) using an applicator brush as described in example 1 and maintained, after loading with fatty acid chloride, at the acylation temperature in a thermo statically controlled oven. The applicator brush, after loading, is wrapped in aluminum foil to maintain its temperature and placed in the thermostatically controlled oven at the acyla tion temperature. Fatty acid chloride at the acylation temperature is applied by point con tact, as described in example 1, of the hot applicator brush on the blotting paper at room temperature after removing the aluminum foil. At the end of this contact, the blotting paper is placed for a few minutes in an oven at a temperature of 180°C to allow the development of the acylation reaction, then cooled to room temperature. The hydrophobicity of the treated blotting paper is evaluated by immersion in distilled water. The hydrophobic nature of the blotting paper obtained makes it possible to evaluate the effectiveness of the acyla tion. The hydrophobic character of blotting paper is evaluated by measuring the dimen sions of the hydrophobic spot formed and also by the intensity thereof which reflects its resistance to wetting.

[0108] It is observed that the application of the reagent by the applicator brush maintained at room temperature produces a limited hydrophobic spot corresponding to the deposition zone of the fatty acid chloride. When the temperature of the applicator brush increases, the spots observed increase in size and in hydrophobicity intensity up to a temperature limit value beyond which the hydrophobicity decreases. This limit value is of the order of 200°C for palmitic acid chloride (C 16) and of the order of 220°C for stearic acid chloride (C1 8 ).

[0109] These results indicate that the effectiveness of the acylation and the quality of the grafting obtained depend on the temperature of the applicator brush and the filiform elements thereof, and on the temperature of the reactive composition comprising the fatty acid chlo ride retained by the filiform elements. Unexpectedly, the heating of the fatty acid chloride retained by the applicator brush, which inevitably favors a shift of the liquid/vapor equilib rium of the fatty acid chloride toward the vapor state, does not actually lead to a loss of the fatty acid chloride in the gaseous state by diffusion into the atmosphere, but allows grafting of the fatty acid chloride in the gaseous state onto the paper material, substantially without allowing liquid fatty acid chloride to remain on the paper material.

[0110] The invention therefore goes against a preconception from the prior art according to which fatty acid chloride must necessarily be deposited in the essentially liquid state by printing on a moving paper web in order to allow the acylation of this paper web by heating the fatty acid chloride deposited on the paper web.

[0111] EXAMPLE 3 - Application conditions - Hot applicator brush - Paper material at variable temperature Fatty acid (palmitic acid C1 6 or stearic acid C1 8) chloride is applied to a paper material heated to a temperature above room temperature, by means of a hot applicator brush im pregnated with the corresponding acid chloride. The applicator brush impregnated with palmitic acid chloride (C 16) is maintained at a temperature of 200°C and the applicator brush impregnated with stearic acid chloride (C 1 8) is maintained at a temperature of 220°C as described in example 1. Fatty (palmitic or stearic) acid chloride is applied to a piece of blotting paper (Canson, 125 g/m2 ) placed in an oven at the acylation temperature. Immedi ately after the application of the fatty acid chloride, the piece of blotting paper which was the subject of this application is covered with a second piece of blotting paper as a devel oper piece of paper. The superposition of the two "emitter/developer" pieces is maintained in the oven for a few minutes at the acylation temperature. The hydrophobicity imparted to the developer piece is indicative of an excess of fatty acid chloride on the emitter piece of paper, that has not reacted with this emitter piece of paper at the acylation temperature.

[0112] The combination of a hot deposition of palmitic acid chloride (C 16) by means of an appli cator brush heated to a temperature of 200°C on a piece of emitter blotting paper brought to a temperature of 140°C, 170°C or 200°C makes it possible to demonstrate that the acyla tion is promoted by blotting paper at a higher temperature, notably at a temperature close to (or equal to) the temperature of the applicator brush and of the fatty acid chloride associ ated with the brush. The developer piece superposed on the emitter piece itself brought to 140°C has a high hydrophobicity. The hydrophobicity of the developer piece decreases when the emitter piece has been brought to a temperature of 170°C, to be almost undetecta ble when the emitter piece has been brought to a temperature of 200°C.

[0113] The combination of a hot deposition of stearic acid chloride (Ci8 ) by means of an applica tor brush heated to a temperature of 220°C on a piece of emitter blotting paper itself brought to a temperature of 160°C, 190°C or 220°C makes it possible to demonstrate that the acylation is promoted by blotting paper at a higher temperature, notably at a tempera ture equal to the temperature of the applicator brush and of the fatty acid chloride associ ated with the brush. The developer piece superposed on the emitter piece itself brought to 160°C has a high hydrophobicity. The hydrophobicity of the developer piece decreases when the emitter piece has been brought to a temperature of 190°C, to be almost undetecta ble when the emitter piece has been brought to a temperature of 220°C.

[0114] The presence and amount of residual free acid chloride on the piece of emitter paper de pends strongly on the temperature of the applicator brush and on the temperature of the fatty acid chloride associated with the brush and on the temperature of the piece of paper on which the fatty acid chloride is deposited.

[0115] The combination of a hot deposition of fatty acid chloride by means of an applicator brush heated to the acylation temperature of between 160°C and 220°C on a piece of paper mate rial itself brought to the acylation temperature makes it possible to obtain an optimal acyla tion of the paper material for a reduced treatment time - notably almost complete in 1/10 of a second - and compatible with on-the-go treatment of a moving paper web. Such an opti mal acylation can of course only be obtained by controlling and adjusting the amount of fatty acid chloride deposited on the paper material, as a deposit of an amount of fatty acid chloride greater than the stoichiometric amount of accessible hydroxyls on the paper mate rial will allow a residue of fatty acid chloride to remain on the surface of the paper mate rial.

[0116] EXAMPLE 4 - Application conditions - Hot applicator brush - Hot paper material - Suc cessive depositions A succession of hot depositions of a fatty acid chloride is carried out on the same zone of a piece of blotting paper, referred to as the emitter piece, each deposition of the succession of depositions being carried out as described in example 3 by means of a hot applicator brush loaded with fatty acid chloride. After each hot deposition of the succession of depositions, a piece of developer paper is superposed on the emitter piece, the superposition of the two "emitter/developer" pieces being maintained in an oven for a few minutes at the acylation temperature. The hydrophobicity imparted to the developer piece is indicative of an excess of fatty acid chloride on the emitter piece of paper, that has not reacted with this emitter piece of paper at the acylation temperature. The hydrophobicity of the emitter piece in creases with the number of depositions. The hydrophobicity of the developer piece corre sponding to the first two depositions remains low but increases with the third deposition. It emerges from this example that the acylation takes place during the first two depositions without significant release of fatty acid chloride from the emitter piece, only the third dep osition being accompanied by a significant release of fatty acid chloride leading to acyla tion of the third developer sheet. For greater efficiency of the chromatographic acylation reaction, it is desirable to carry out acylation at a high temperature compatible with the thermal resistance of the paper material and to carry out several successive depositions of reduced amounts of fatty acid chloride. This is accentuated by the fact that the grafting of the fatty acid chloride on the paper material and the immobilization thereof has the effect of shifting, via the mass effect, the liquid/vapor equilibrium of the fatty acid chloride to ward the formation of fatty acid chloride vapor and the grafting thereof on the paper mate rial. The paper material and the surface hydroxyl groups behave like a specific "pump" of the fatty acid chloride in the vapor state which will tend to lower the concentration of the fatty acid chloride in the vapor state on the substrate and promote the diffusion of the rea gent from the applicator brush to the paper material.

[0117] The effectiveness of the chromatogenic acylation reaction is defined by evaluating the hy drophobicity of the acylated solid material by measuring the contact angle formed between the main plane of the acylated solid material and a drop of pure water deposited on the sur face of the acylated solid material. Typically, a contact angle value of an acylated solid ma terial is between 900 and 150°, the contact angle value of 150° corresponding to a particu larly hydrophobic and water-repellent material. The quality of acylation is also defined by measuring the period of time during which the contact angle value of between 90° and 150° is maintained at room temperature and by the pocket of water test. The pocket of wa ter test can only be carried out with a solid material in the form of a substantially square flexible sheet enabling the comers thereof to be gathered together to form a pocket of wa ter. The impermeability of this pocket of water is analyzed by monitoring the loss of water (taking into account the evaporation).

[0118] The hydrophobicity can also be evaluated by observation of the water repellency. 1 ml of distilled water is deposited on the surface of the solid material and it is observed whether the drop of water formed rolls over the surface, by clinging or not clinging to the surface of the solid material. A satisfactory water repellency corresponds to a contact angle of approx imately 150°.

[0119] The invention may be the subject of numerous variants and applications other than those described above. In particular, it goes without saying that, unless stated otherwise, the vari ous structural and functional features of each of the embodiments described above should not be considered to be combined with and/or intimately and/or inextricably linked to one another but, on the contrary, to be mere juxtapositions. Moreover, the structural and/or functional features of the various embodiments described above may be the subject, as a whole or in part, of any different juxtaposition or any different combination.

Claims

Claims 1. A process for the chromatogenic acylation of a solid material (1, 2) bearing hydroxyl groups that are accessible to at least one fatty acid chloride in the gaseous state and that are capable of reacting with this (these) fatty acid chloride(s) in the gaseous state, wherein: at least one composition, referred to as reactive composition (20, 21, 22), of at least one fatty acid chloride is applied at least on the surface of said hydroxylated solid material (1, 2) by means of at least one applicator device (3, 15, 28) having an application surface formed of filiform elements (4, 16, 29) that are not reactive with said reactive composition (20, 21, 22) and that are able to release said reactive composition (20, 21, 22) at least on the surface of said hydroxylated solid material (1, 2) by contact of the filiform elements (4, 16, 29) and the hydroxylated solid material (1, 2), characterized in that said reactive composition (20, 21, 22) applied by the applicator device (3, 15, 28) at least on the surface of said hydroxylated solid material (1, 2) is, during the application thereof, at a temperature, referred to as acylation temperature, below the vaporization temperature of at least one fatty acid chloride of said reactive composition (20, 21, 22) and chosen to enable an acylation of said solid material (1, 2) by reaction of at least one fatty acid chloride in the gaseous state of said reactive composition (20, 21, 22) with at least one of the hydroxyl groups of said solid material (1, 2), said acylation temperature being between 160°C and 250°C.
2. The process as claimed in claim 1, characterized in that at least one application surface portion of the applicator device (3, 15, 28) is in contact with a surface portion of the hydroxylated solid material (1, 2), at least this surface portion of the hydroxylated solid material (1, 2) is at said acylation temperature during application of said reactive composition (20, 21, 22) to the hydroxylated solid material (1, 2).
3. The process as claimed in claim 1 or 2, characterized in that the filiform elements (4, 16, 29) forming the application surface are at said acylation temperature during the application of said reactive composition (20, 21, 22) to the hydroxylated solid material (1, 2).
4. The process as claimed in any one of claims I to 3, characterized in that said reactive composition (20, 21, 22) is applied at least on the surface of said hydroxylated solid material (1, 2), in a thermoregulated chamber (39) suitable for maintaining said reactive composition (20, 21, 22) released by the applicator device (3, 15, 28) at said acylation temperature.
5. The process as claimed in any one of claims 1 to 4, characterized in that it comprises at least one step of redistributing fatty acid chloride(s) deposited on the hydroxylated solid material, without a fresh supply of said reactive composition (20, 21, 22), the redistribution step being carried out by means of at least one distributor device having an application surface formed of filiform elements which are not reactive with the fatty acid chlorides of said reactive composition and are able to be loaded with fatty acid chlorides deposited on the hydroxylated solid material, by contact of the filiform elements of the distributor device with the hydroxylated solid material (1, 2) and in order to release at least some of the loaded fatty acids, in contact with said hydroxylated solid material (1, 2) by contact of the filiform elements with the hydroxylated solid material (1, 2), the distributor device being at a temperature of between 160°C and 250°C.
6. The process as claimed in any one of claims I to 5, characterized in that at least one reactive composition (20, 21, 22) comprises at least one fatty acid chloride chosen from the group formed of palmitic acid chloride (C16), stearic acid chloride (C18), arachidic acid chloride (C20) and behenic acid chloride (C22).
7. The process as claimed in any one of claims 1 to 6, characterized in that the hydroxylated solid material (1, 2) is a paper material.
8. The process as claimed in any one of claims I to 7, characterized in that the hydroxylated solid material (1, 2) is formed of a paper web (2, 10, 12, 25) moved in a run direction (42) parallel to the largest dimension of the web (2, 10, 12, 25, 35), between an upstream reel (66) of said paper web (2, 10, 12, 25, 35) and a downstream take-up roll (36) for a web (12, 25, 35) of acylated paper.
9. The process as claimed in claim 8, characterized in that at least one reactive composition (20, 21, 22) is applied at fixed station(s) at least on one main face of the moving paper web (2, 10, 12, 25).
10. The process as claimed in claim 8 or 9, characterized in that at least one applicator device (3, 15, 28) is a roller with an axis of rotation parallel to the plane of the paper web (2, 10, 12, 25) and not parallel to the run direction (42).
11. The process as claimed in any one of claims 8 to 10, characterized in that it comprises at least two applications of reactive composition(s) (20, 21, 22) at fixed stations on the moving paper web, each reactive composition (20, 21, 22) being at said acylation temperature during the application thereof.
12. The process as claimed in any one of claims 8 to 11, characterized in that the solid material (1, 2) is a paper material coated with polyvinyl alcohol.
13. The process as claimed in any one of claims 8 to 12, characterized in that the filiform elements (4, 16, 29) of at least one applicator roller (3, 15, 28) are supplied by centrifugal diffusion of said reactive composition (20, 21, 22) from an axial lumen of this applicator roller (3, 15, 28) rotated upon itself.
14. The process as claimed in claim 13, characterized in that said reactive composition (20, 21, 22) is introduced into the axial lumen of the applicator roller (3, 15, 28) by means of a bar for distributing said reactive composition (20, 21, 22) over the length of the axial lumen, the distribution bar extending over substantially the entire length of the axial lumen.
15. The process as claimed in any one of claims 8 to 14, characterized in that at least one applicator roller (3, 15, 28) is provided with means for heating said reactive composition (20, 21, 22) to said acylation temperature.
16. The process as claimed in any one of claims 8 to 15, characterized in that a withdrawal of fatty acid chloride(s) on the paper web (12, 25, 35) is carried out using a recovery device (62) having a rotatable recovery surface (63) provided with filiform elements which are not reactive with said reactive composition and are able to: - be loaded with fatty acid chloride(s) by contact of the recovery surface (63) and the paper web (12, 25, 35), and - release fatty acid chloride(s) by applying a flow of gaseous composition (64) heated to a temperature above said acylation temperature, the flow of gaseous composition (64) being applied in contact with the recovery surface (63).
17. The process as claimed in any one of claims I to 16, characterized in that thefiliform elements (4, 16, 29) are formed from at least one material chosen from the group formed of aramid fibers and microfibers and inorganic fibers and microfibers.
18. The process as claimed in any one of claims I to 17, characterized in that at least one portion of gaseous hydrochloric acid formed due to the chromatogenic acylation is entrained by a flow of a gaseous composition circulating in contact with the solid material (1, 2), at said acylation temperature.
19. The process as claimed in any one of claims I to 18, characterized in that said reactive composition (20, 21, 22) is free of any solvent medium.