PROCESS FOR ACYLATION OF A HYDROXYLATED SOLID MATERIAL
20230265613 · 2023-08-24
Inventors
Cpc classification
D21H19/12
TEXTILES; PAPER
D21H17/18
TEXTILES; PAPER
C08B3/10
CHEMISTRY; METALLURGY
International classification
D21H17/18
TEXTILES; PAPER
D21H19/12
TEXTILES; PAPER
Abstract
A process for acylation of a solid material (3, 9) bearing reactogenic hydroxyls includes at least one fatty acid chloride (1) is distributed at least on the surface of the solid material (3, 9) using a distributor device (2) having an application surface. At least one fatty acid chloride (1) is distributed at least on the surface of the solid material (3, 9) is heated at a temperature, referred to as acylation temperature, below the vaporization temperature of the at least one fatty acid chloride (1), so as to enable an acylation of the solid material (3, 9). A stream of a gaseous composition (6) is directed over the said solid material (3, 9) at the acylation temperature, so as to entrain at least one portion of gaseous hydrochloric acid (7) formed by the acylation reaction
The application surface of the distributor device (2) is a velvet provided with velvet filiform elements that are suitable for taking up the at least one fatty acid chloride (1) by contact with the at least one fatty acid chloride, and releasing at least one fatty acid chloride by bringing the filiform elements of the velvet into contact with the solid material (3, 9). The distribution step (12, 14) is carried out so as to distribute over the solid material (3, 9) an amount of the at least one fatty acid chloride (1) of between 20 mg/m.sup.2 and 1 g/m.sup.2 surface area of the solid material (3, 9).
Claims
1. A process for acylation of a solid material bearing hydroxyls (—OH), referred to as reactogenic hydroxyls, which are accessible and capable of reacting with a fatty acid chloride in the gaseous state, said process comprising the steps of: at least one fatty acid chloride is distributed at least on the surface of said solid material using a distributor device having an application surface suitable for depositing said at least one fatty acid chloride at least on the surface of said solid material from said application surface; said at least one fatty acid chloride distributed at least on the surface of said solid material is heated, at a temperature, referred to as acylation temperature, below the vaporization temperature of said at least one fatty acid chloride, so as to enable an acylation of said solid material by reaction of at least one fatty acid chloride in the gaseous state over at least one of said reactogenic hydroxyls of said solid material, and; a stream of a gaseous composition is directed over said solid material at said acylation temperature, so as to entrain at least one portion of gaseous hydrochloric acid formed by the acylation reaction; wherein the application surface of the distributor device is a velvet provided with velvet filiform elements that are non-reactive with respect to said at least one fatty acid chloride and are suitable for: taking up said at least one fatty acid chloride by contact with said at least one fatty acid chloride, and; releasing said at least one fatty acid chloride by bringing the filiform elements of the velvet into contact with said solid material; the distribution step being carried out so as to distribute over said solid material an amount of said at least one fatty acid chloride of between 20 mg/m.sup.2 and 1 g/m.sup.2 surface area of said solid material.
2. The process according to claim 1, wherein said at least one fatty acid chloride is distributed at least on the surface of said solid material by brushing of free longitudinal ends of the velvet filiform elements of the application surface over the surface of said solid material.
3. The process according to claim 1, wherein the distributor device comprises at least one applicator roller having said application surface, said at least one applicator roller being rotatably mounted with respect to said solid material and in that said at least one fatty acid chloride is distributed by rotating said at least one applicator roller, said application surface being in contact with said solid material.
4. The process according to claim 3, wherein the solid material being in the form of a strip moved in a run direction parallel to the largest dimension of the strip, between a reel upstream of said strip and a take-up roll downstream of a strip of acylated solid material; said at least one fatty acid chloride is deposited continuously on at least one free surface of said moving solid material, and; said at least one fatty acid chloride deposited on the surface of said solid material is distributed at least on the surface of said solid material by means of the distributor device, and; said solid material is heated so that said at least one fatty acid chloride distributed at least on the surface of said solid material reaches said acylation temperature on said solid material, and; the stream of gaseous composition is directed over said solid material at said acylation temperature, whereby said solid material is acylated.
5. The process according to claim 4, wherein said at least one acid chloride is deposited continuously on at least one of the free main surfaces of said solid material by means of a printing device.
6. The process according to claim 5, wherein the printing device is chosen from the group formed of flexographic printing devices and heliographic printing devices.
7. The process according to claim 3, wherein said solid material being in the form of a strip moved in a run direction parallel to the largest dimension of the strip, between a reel upstream of said strip and a take-up roll downstream of a strip of acylated solid material; said at least one fatty acid chloride is deposited continuously on the applicator roller rotated in contact with said solid material, whereby said at least one fatty acid chloride is distributed at least on the surface of said solid material from the rotated applicator roller, and; said solid material is heated so that said at least one fatty acid chloride distributed at least on the surface of said solid material reaches said acylation temperature, and; the stream of gaseous composition is directed over the paper material at said acylation temperature.
8. The process according to claim 7, wherein said at least one fatty acid chloride is deposited on the rotated applicator roller, by contact of said rotated applicator roller with an anilox roller of a printing device loaded with said at least one fatty acid chloride.
9. The process according to one of claim 1, wherein the velvet filiform elements are formed of at least one material chosen from the group formed of keratin fibres, aramid fibres, polyester fibres, polyamide fibres, acrylic fibres, fluorinated fibres, fibres provided with a fluorinated coating, microfibres, woven microfibres, super-microfibres and ultra-microfibres.
10. The process according to one of claim 1, wherein said at least one acid chloride is deposited on the surface of said solid material by means of a distributor device having an application surface previously loaded with said at least one fatty acid chloride.
11. The process according to claim 10, wherein said solid material is a disposable tissue.
12. The process according to one of claim 1, wherein the velvet filiform elements have a length between 1 mm and 10 mm.
13. The process according to claim 4, wherein the rotatable applicator roller is rotated with an angular speed of rotation chosen so that the free ends of the velvet filiform elements are rotated with a linear velocity having a value different from the value of the run speed of said solid material.
14. The process according to claim 4, wherein the rotatable applicator roller is rotated in a direction of rotation chosen so that the free ends of the velvet filiform elements are moved countercurrent to the movement of the strip of said solid material.
15. The process according to claim 4, wherein the rotatable applicator roller is rotated in a direction of rotation chosen so that the free ends of the velvet filiform elements are moved concurrent to the movement of said solid material.
16. The process according to claim 1, wherein the velvet filiform elements have a flexibility chosen so as not to damage said solid material by contact with said solid material.
17. The process according to claim 1, characterized in that said solid material has an outer surface layer formed of polyvinyl alcohol.
18. The process according to claim 1, a composition, referred to as acylation composition, comprising said at least one fatty acid chloride and acetyl chloride is distributed at least on the surface of said solid material.
Description
[0085] Other objectives, characteristics and advantages of the invention will become apparent on reading the following description which refers to the appended figures and to the examples given purely without limitation of the invention and in which:
[0086]
[0087]
[0088] In a process according to the invention for acylation of a solid material bearing hydroxyl groups (—OH), referred to as reactogenic hydroxyls, which are accessible and capable of reacting with a fatty acid chloride in the gaseous state, notably for acylation of a cellulosic material, in particular of a paper material, at least one fatty acid chloride is distributed on the surface and over at least one thickness portion of said solid material by means of a distributor device having an application surface suitable for depositing said at least one fatty acid chloride from said application surface at least on the surface of said solid material. The application surface of the distributor device is a velvet provided with velvet filiform elements that are not reactive with respect to said at least one fatty acid chloride. The applicator device comprises at least one applicator roller having said application surface, said at least one applicator roller being rotatably mounted relative to the flat material. The applicator roller may be an applicator roller or “varnish” roller of “velvet” type. By way of nonlimiting example, it may be: [0089] a “Nespoli” velvet roller (Nespoli Group, La Capelle, France), the application face of which is formed of a velvet provided with filiform elements comprising textile fibres coated with Teflon® and that are at least partially oleophobic. For example, such a velvet roller has a length of the order of 10 cm and a diameter of 30 mm. The length of the fibres is between 4 mm and 12 mm, and preferably of the order of 5 mm; [0090] a “DIALL” varnish roller (Kingfisher International Products Limited, London, Great Britain), the application surface of which is of cylinder of revolution shape, having a length of 110 mm and having a transverse cross-sectional diameter of 40 mm and the application face of which comprises mohair fibres; [0091] a “Roulor Professionnel” varnish roller (Nespoli Group, La Capelle, France), the application face of which is formed of a velvet provided with filiform elements comprising polyester fibres coated with Teflon® and that are at least partially oleophobic; [0092] a pure wool velvet roller (OCAI, Domont, France), the fibres of which have a length of 4 mm.
[0093] The inventors observed that the use of a step of distributing the acid chloride(s) over said solid material, by means of such an applicator roller of “varnish” or “velvet” type in a chromatogenic acylation process according to the invention makes it possible to obtain an acylated solid material having hydrophobicity properties at least equivalent, for the same amounts of reactant deposited, to the hydrophobicity properties of paper materials treated by the process for impregnation of the paper material with a solution of fatty acid chloride in pentane (WO99/08784), but with the considerable advantage of not using solvent, notably organic solvent. The hydrophobic properties obtained by the use of a process according to the invention are, at an equal amount of fatty acid chloride deposited, even better than those obtained with the method of impregnation by a solution of fatty acid chloride in petroleum ether 100/150 or with a deposition of fatty acid chloride by means of an anilox roller. These two prior art processes result in acylated solid materials, the hydrophobicity of which is disappointing, inevitably use excess fatty acid chloride and require a complex step of eliminating the excess fatty acid chloride by hot air blowing.
[0094] The quality of the acylation is defined by evaluating the hydrophobicity 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 surface of the acylated solid material. Typically, a contact angle value of an acylated solid material is between 90° and 150°, the contact angle value of 150° corresponding to a particularly hydrophobic and water-repellent material. The quality of the acylation is also defined by measuring the period of time during which the contact angle value of between 90° and 150° is maintained at ambient temperature and by the pocket of water test. The pocket of water test can only be carried out with a solid material in the form of a substantially square flexible sheet enabling the corners thereof to be gathered together to form a pocket of water. The impermeability of this pocket of water is analysed by monitoring the loss of water (taking into account the evaporation).
[0095] 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 around 150°.
[0096] The inventor was able to observe that the value of the contact angle formed between the main plane of a solid material acylated by a process for impregnation of a solution of fatty acid chloride in pentane and by a process according to the invention is close to 150°, whereas the contact angle values measured on a solid material acylated according to a process for impregnation by a solution of fatty acid chloride in petroleum ether 100/150 and by deposition by means of an anilox roller are at most equal to 130°.
Characterization of the Presence of Residual Fatty Acid Chloride during the Acylation—Revealing Test
[0097] The fact that the amount of fatty acid chloride deposited on a first piece of a solid material, referred to as piece to be acylated, reacts only partially or reacts completely with said solid material of said piece to be acylated is characterized by depositing on said piece to be acylated a given amount of fatty acid chloride and by placing in contact with the main face of said piece to be acylated, opposite the face for receiving the stream of hot air intended to promote the change of the fatty acid chloride from the liquid state to the gaseous state and to entrain the hydrochloric acid formed by the acylation reaction, a sheet of any paper, referred to as a revealing sheet. When the fatty acid chloride is present in excess, it is entrained by the stream of air into contact with said revealing sheet where it reacts with said reactogenic hydroxyls of the cellulose fibres. Said revealing sheet is analysed with respect to its hydrophobicity properties. If the given amount of fatty acid chloride placed in contact with said piece to be acylated is such that fatty acid chloride does not react with said piece to be acylated and is transported by the stream of air into contact with said revealing sheet, then the hydrophobicity properties of said revealing sheet are increased. If, on the contrary, the given amount of fatty acid chloride placed in contact with said piece to be acylated is such that most or all of the fatty acid chloride deposited on said piece to be acylated reacts with said piece to be acylated, then said revealing sheet remains barely or not at all hydrophobic.
[0098] It was observed that under conditions strictly comparable with those described in example 1 below, the acylation process according to the invention and also the process for acylation by impregnation using a solution of acid chloride at 0.1% in pentane do not result in an increase in the hydrophobicity of said revealing sheet. This result indicates that the fatty acid chloride reacts in the vast majority with said piece to be acylated. On the contrary, the process by impregnation in petroleum ether 100/150 and the process by flexographic/heliographic deposition require an excess of acid chloride and result in the formation of highly hydrophobic revealing sheets. The process according to the invention makes it possible to retain the excellent results obtained by the pentane impregnation method by depositing very small amounts of fatty acid chloride but with the considerable advantage of not using organic solvent.
[0099] A first embodiment of a process according to the invention for acylation of a paper material is represented schematically in in which R is a hydrocarbon-based chain having a number of carbon atoms between 17 (limit included) and 29 (limit included). In such a process according to the invention, a distributor device 2 is also chosen that has an application surface suitable for depositing said at least one fatty acid chloride 1 from said application surface at least on the surface of said solid material. In the embodiment represented in
[0100] During a first step 11 of loading the varnish roller 2, the varnish roller 2 being in the new state and not loaded with fatty acid chloride, an amount of the order of 1 mL of fatty acid chloride is placed in the flat-bottomed container. During this first step 11 of loading the varnish roller 2, the varnish roller 2 is driven manually so that the varnish roller 2 moves in contact with the fatty acid chloride 1 so that the filiform elements of the varnish roller 2 take up the fatty acid chloride 1 over the whole of the application surface of the varnish roller 2. For the purposes of limiting the amount of fatty acid chloride 1 loaded on the varnish roller 2, an optional step of removing an excess of fatty acid chloride 1 from the varnish roller 2 is carried out by rolling said varnish roller 2 successively over several sheets of paper so as to use up the excess fatty acid chloride. A varnish roller 4 loaded with fatty acid chloride 1 is thus obtained. Such a step of removing the excess fatty acid chloride 1 is in particular necessary during the use of a distributor roller having an oleophobic velvet.
[0101] That being said, during a subsequent step 11 of loading the varnish roller 2, the varnish roller 2 having been previously loaded and used for the application of fatty acid chloride on a solid material, an amount of fatty acid chloride of the order of 50 μL is placed in the flat-bottomed container.
[0102] A piece 3 of a solid material, for example a disposable tissue 3, is chosen. The piece 3 of paper material is placed on a suitable support so as to be able to transfer an amount of fatty acid chloride 1 from the loaded varnish roller 4 to the disposable tissue 3. This application 12 is carried out by rolling the thus loaded varnish roller 4 over the surface of the disposable tissue 3. Preferably, this rolling 12 is carried out without exerting pressure other than the pressure needed for rolling the varnish roller 4 over the disposable tissue 3 (that is to say a moderate pressure of between 0.1 and 0.2 kg/cm.sup.2). In this way, only a small amount of fatty acid chloride 1 is transferred onto the disposable tissue 3. However, the inventor has observed that even though this amount of fatty acid chloride 1 transferred onto the disposable tissue 3 is small, it is in any case sufficient to subsequently enable an acylation of the disposable tissue 3 and give it hydrophobicity properties at least equivalent to the hydrophobicity properties obtained by impregnation of a fatty acid chloride from a solution in pentane (WO99/08784), but without the use of organic solvent. Thus, a piece 5 of a disposable tissue loaded with fatty acid chloride 1 is formed. The inventor believes that the fatty acid chloride 1 applied on the surface of the disposable tissue 3 is distributed, owing to the filiform elements of the varnish roller 2, on the surface of the loaded disposable tissue 5 but also at least at depth in the loaded disposable tissue 5 and in contact with the cellulose fibres of the loaded disposable tissue 5. Specifically, the inventor believes that the filiform elements of the varnish roller 2 which are flexible and elastically deformable in a transverse manner make it possible to distribute the fatty acid chloride 1 by brushing over at least one thickness portion of the disposable tissue 3. The inventor believes that, taking into account the absence of solvent, the fatty acid chloride 1 does not form clusters during the evaporation of an organic solvent and is distributed substantially uniformly over the cellulose fibres of the loaded disposable tissue 5.
[0103] In the first embodiment of a process according to the invention represented in ) is released. The stream of air 6 applied over the loaded disposable tissue 5 makes it possible to move hydrochloric acid formed by the reaction away from the loaded disposable tissue 5 so that the equilibrium of the acylation reaction is shifted in the direction of the formation of the acylated disposable tissue 10.
[0104] In the embodiment of a process according to the invention represented in
[0105] A second embodiment of a process according to the invention for acylation of a paper material is represented schematically in
[0106] A device for moving a strip 9 of a paper material moved between an upstream reel and a downstream device for rewinding a strip 10 of acylated paper is chosen as described in FR2967363. In certain embodiments, the strip 9 of paper material is moved at a speed of between 30 and 100 metres per minute. At least one fatty acid chloride 1 is chosen from the group formed of fatty acid chlorides of formula R—CO—C in which R is a hydrocarbon-based chain having a number of carbon atoms between 17 (limit included) and 29 (limit included). A step 15 of continuously depositing said at least one fatty acid chloride 1 on the moving strip 9 of paper is carried out by any suitable means known to a person skilled in the art. These means may be an upstream printing device chosen from the group formed of flexographic printing devices and heliographic printing devices. Via this deposition step 15, a paper material 8 coated with fatty acid chloride 1 is formed. In the downstream position relative to the printing device, the paper material 8 coated with fatty acid chloride 1 is subjected to a step 14 of redistributing and spreading the fatty acid chloride 1 on the surface over at least one depth portion of the coated paper material 8. This redistribution/spreading step is carried out by subjecting the surface of the moving strip of coated paper 8 to a brushing with a distributor device 2 comprising an application surface formed of a velvet provided with velvet filiform elements that are not reactive with respect to said at least one acid chloride. Advantageously, the distributor device comprises a varnish roller 2 rotated countercurrent to or in the run direction of the strip of coated paper material 8. The velvet filiform elements, whether they are oleophilic or oleophobic, are suitable for: [0107] taking up said at least one fatty acid chloride by contact with said at least one fatty acid chloride, and; [0108] releasing said at least one fatty acid chloride by contact of the velvet filiform elements with the strip of coated paper material 8.
[0109] Owing to this redistribution/spreading step 14, a strip of solid material 5 loaded with an amount of said at least one fatty acid chloride is formed. The inventor observed in particular that even in the case where the amount of fatty acid chloride 1 transferred to the strip 5 of said solid material is small and of the order of 20 mg/m.sup.2, it is in any case sufficient to subsequently enable an acylation of said solid material and to give it hydrophobicity properties at least equivalent to the hydrophobicity properties obtained by impregnation of a fatty acid chloride from a solution in pentane (WO99/08784), but without the use of organic solvent.
[0110] In the second embodiment of a process according to the invention represented in ) is released. The stream of air 6 applied over the loaded strip 5 makes it possible to move hydrochloric acid formed by the reaction away from the strip 5 in the form of a composition 7 of air loaded with hydrochloric acid so that the equilibrium of the acylation reaction is shifted in the direction of the formation of the acylated paper material 10.
EXAMPLE 1—ACYLATION ACCORDING TO THE INVENTION OF A SOLID MATERIAL—DETERMINATION OF OPTIMAL CONDITIONS FOR DEPOSITION OF STEARIC ACID CHLORIDE
[0111] Approximately 1 mL of undiluted stearic acid chloride is placed in a flat-bottomed tray. A varnish roller (“DIALL”, Kingfisher International Products Limited, London, Great Britain) is impregnated with stearic acid chloride by rolling the varnish roller over the bottom of the flat-bottomed tray. The varnish roller is of a cylinder of revolution shape having a diameter of 40 mm, a length of 100 mm and having filiform elements made of mohair wool having a mean length of 5 mm. The impregnation is homogenized by rolling the roller over the bottom of a flat container, whereby all of the stearic acid chloride is transferred to the varnish roller. A plurality of square disposable tissues (Kleenex®, Kimberly-Clark Corporation) with dimensions of 21 cm×21 cm are chosen. Each disposable tissue is formed of four superposed layers of paper, each layer having an approximate mass of 0.5 g (11 g/m.sup.2). Stearic acid chloride is deposited on one of the main faces of a first tissue, referred to as tissue to be acylated, of the plurality of disposable tissues by rolling the roller in contact with the whole of one of the two faces of this first tissue and by applying to the varnish roller a moderate pressure suitable for enabling a partial squashing of the filiform elements of the roller. To do this, a substantially vertical force directed from top to bottom and having a value between of the order of 5 N and of the order of 20 N is exerted on the roller, while making sure not to deteriorate the tissue. Stearic acid chloride impregnated on the varnish roller is thus deposited successively on one face, referred to as deposition face, of each of the tissues of the plurality of tissues to be acylated and without reloading the varnish roller. After deposition of the stearic acid chloride, a virgin disposable tissue, referred to as revealing tissue, is placed on the face opposite said deposition face of each tissue to be acylated, and each assembly formed of the tissue to be acylated surmounted by said corresponding revealing tissue is introduced into a ventilated oven at 150° for 2 minutes. Each pair of tissues formed of a tissue to be acylated and said corresponding revealing tissue is removed from the ventilated oven. After cooling, the hydrophobicity of said deposition face of the tissue to be acylated and the hydrophobicity of the face opposite said deposition face are analysed. The hydrophobicity of said revealing tissue is also analysed. It is observed that both faces of the tissues of the plurality of successively impregnated tissues have a high hydrophobicity revealed by a constant contact angle with water of 150° over the entire surface of the tissue. The hydrophobicity of said revealing tissue is initially high which indicates that the amount of stearic acid chloride deposited on the first tissues in their order of impregnation is greater than the maximum amount of stearic acid chloride capable of being grafted to such a tissue. However, it is observed that this hydrophobicity decreases with the impregnation placement of the tissue and becomes heterogeneous. This indicates that the roller is less and less loaded with reactant. The successive impregnation of tissues in series makes it possible to obtain acylated tissues that have an excellent hydrophobicity and at the same time a low hydrophobicity on said corresponding revealing tissue. The roller is in that case optimally loaded with stearic acid chloride. It is observed that it is possible to continue to deposit stearic acid chloride on a large number of tissues without the hydrophobicity obtained decreasing substantially.
EXAMPLE 2—QUANTIFICATION
[0112] A tissue is weighed with a precision balance before deposition and after deposition of stearic acid chloride with the roller loaded with stearic acid chloride in an optimal manner as described in example 1. A value of 1 mg of stearic acid chloride per face on average is found. A value of 2 mg is found when the stearic acid chloride is deposited on both faces. The amount of stearic acid chloride deposited is of the order of 45 mg/m.sup.2 of solid material; the hydrophobicity properties are excellent without the use of a nonpolar solvent of pentane type.
EXAMPLE 3—REPRODUCIBILITY
[0113] After having carried out a first deposition of stearic acid chloride and determined the amount deposited by weighing, the operation is repeated 4 times, weighing the tissue each time. It is observed that each deposition of stearic acid chloride results in an additional increase of 1 mg. An amount of 5 mg was thus deposited. This example shows that the deposition of stearic acid chloride by means of a roller is reproducible.
EXAMPLE 4—OPTIMIZATION OF THE LOADING OF THE ROLLER
[0114] The operation for loading the roller as in example 1 is repeated with the deposition of the stearic acid chloride but without applying said revealing tissue. After one minute in the oven at 150° C., the door is opened. During the heating of the first tissues, a fog of condensation is observed. This then decreases gradually with the tissues treated. When it is observed that the fog of condensation has practically disappeared, the tissue is tested for its hydrophobicity and it is observed that the face on which the stearic acid chloride was deposited has a very high hydrophobicity and contact angles of 150°. When the roller loading operation is carried out with 1 mL of stearic acid chloride, the placement of the first tissue of the plurality of tissues to be acylated on which the roller is successively applied and which does not lead to a formation of fog of condensation is in the vicinity of the 30.sup.th placement.
EXAMPLE 5—IMPERMEABILITY
[0115] The impermeable nature of the acylated disposable tissues is demonstrated by suspending each square disposable tissue by its four corners and by pouring an amount of water (10 mL) into the tissue pocket thus formed. The pockets of acylated disposable tissues which were prepared with the roller loaded in an optimal manner as described in example 1 are perfectly watertight over a period of more than 4 days.
EXAMPLE 6—COMPARATIVE EXAMPLE (OUTSIDE THE INVENTION)
[0116] 100 mL of a solution of stearic acid chloride at 0.05% in anhydrous pentane is prepared that makes it possible to impregnate 10 square disposable tissues (Kleenex®, Kimberly-Clark Corporation) with dimensions of 21 cm×21 cm, each disposable tissue retaining around 5 μl of stearic acid chloride. The pentane is eliminated by spontaneous evaporation under a suction hood with dry air having a moisture content of lower than around 20%. No step according to the invention for distributing the stearic acid chloride on the disposable tissues is carried out. Next, one of the disposable tissues is placed in a ventilated oven at a temperature of 150° C. The reaction is left to take place for 2 minutes. Upon opening the door of the ventilated oven, no formation of a fog of condensation of free stearic acid chloride is observed. The disposable tissue obtained is hydrophobic and impermeable to water. A 200 μL drop of distilled water is deposited on the surface of one of the acylated disposable tissues. The drop of water remains formed on the surface of the tissue without spreading. The contact angle has a value close to 150°, attesting to a correct grafting efficiency. A virgin tissue, referred to as a revealing tissue, is placed on top of a second tissue as prepared above, and the assembly is placed in the ventilated oven at 150° C. for 2 minutes. Said revealing tissue is tested with respect to its hydrophobicity and it is observed that this is very low. These two results confirm the fact that when appropriate but very small amounts are applied with the pentane impregnation method, good hydrophobicity values are obtained without excess stearic acid chloride. The invention aims to obtain such hydrophobicity values without the use of organic solvent.
EXAMPLE 7—COMPARATIVE EXAMPLE (OUTSIDE THE INVENTION)
[0117] Solutions of stearic acid chloride at 0.05%, 0.1% and 0.5% in petroleum ether 100/150 are prepared. Tissues are impregnated with these various solutions and also a control produced with pure solvent, the majority of the solvent is left to evaporate and then the tissues are placed in the oven for 2 minutes at 150° C. The door of the oven is then opened and, in all cases, the formation of a fog of condensation is observed. This fog is greater in the case of the solution at 0.5% and smaller in the case of the solvent alone. These results indicate that the petroleum ether 100/150 remains trapped in the fibres of the paper material when it is alone and that it is associated with the reactant when the latter is in excess. It is observed that it is necessary to continue the heating in the oven for a further 2 additional minutes in order to no longer observe the presence of the fog of condensation on opening the door.
[0118] The contact angle values of the various samples are determined and it is observed that the values obtained for 0.05% and 0.1% are 100° and 120° respectively whilst the values obtained for 0.5% are of the order of 150°. The experiment is done again with revealing tissues. A high hydrophobicity is observed for 0.5% but a significant hydrophobicity is also observed for 0.05% and 0.1%. These results indicate that the presence of residual solvent disrupts the correct implementation of the chromatogenic acylation reaction.
EXAMPLE 8—ACYLATION TREATMENT ACCORDING TO THE INVENTION—BRUSHING METHOD
[0119] A “Diall” varnish roller with dimensions of 4×10 cm having filiform elements made of mohair wool, previously loaded with 1 ml of stearic acid chloride is attached to a rod which is then mounted on an adjustable variable speed electric drill. The rotating varnish roller is then moved closer to a disposable tissue to be treated so that the free ends of the filiform elements of the varnish roller brush the surface of the tissue. This is carried out so as not to deteriorate the structure of the tissue. The procedure of example 1 is then followed. Fatty acid chloride is deposited successively on the tissues of a series of disposable tissues until optimal hydrophobicity properties are obtained on the face on which the fatty acid chloride was deposited and a low hydrophobicity is obtained on the face opposite the deposition face. The tissue is weighed before and after deposition. Values of 1 mg of acid chloride per face are obtained, which are equivalent to those deposited by roller according to the method described in example 1. The filiform elements of the velvet have a degree of freedom which enables them to slide over the surface of the tissue and are suitable for efficiently transferring the fatty acid chloride onto the surface of the tissue.
EXAMPLE 9—RELOADING OF THE ROLLER
[0120] The varnish rollers initially loaded with 1 mL of fatty acid chloride (as described in example 1) and used for the coating of sheets of paper material end up running out after the deposition of fatty acid chloride on a large number of sheets of paper material. They are reloaded by depositing 50 μl of fatty acid chloride at the bottom of the deposition container and by making the varnish roller absorb this amount of fatty acid chloride. These reloaded varnish rollers behave like new rollers loaded with 1 mL of reactant. These results are in agreement with the measurements of amounts of deposit of reactant carried out by direct weighing.
EXAMPLE 10—DEEP/SURFACE DISTRIBUTION
[0121] Stearic acid chloride is applied to a disposable tissue composed of a superposition of four associated layers. After application of stearic acid chloride to one of the main faces (layer no. 1) of the tissue by one or other of the methods of examples 1 or 8 above, the various layers are separated and are placed in the oven. It is observed that the first layer (layer no. 1) is highly hydrophobic but the results are different depending on the deposition methods. By application according to the method described in example 1, it is observed that the layer no. 2 is hydrophobic and also the layer no. 3, but to a lesser extent. By application according to the method described in example 8, only the layer no. 1 is highly hydrophobic. These results indicate that the reactant is capable of penetrating to a greater or lesser extent into the thickness of the paper as a function of the deposition method. The method described in example 1 enables the fatty acid chloride to penetrate deeper, whereas the method described in example 8 enables a superficially limited deposition.
EXAMPLE 11—TRANSFER OF REACTANT
[0122] A sheet of kitchen roll is chosen as solid material, which has been loaded according to the method described in example 8 above using a varnish roller reloaded with fatty acid chloride so as to deposit fatty acid chloride mainly on the surface of the sheet of kitchen roll. Virgin rollers are now used and they are applied to this sheet according to one of the methods described in examples 1 and 8. Next, these rollers are used to coat virgin sheets. After coating, these sheets are placed in the oven for 1 minute at 150° C. and tested for their hydrophobicity. It is observed that the sheets coated according to the method described in example 8 are more hydrophobic than those coated according to the method described in example 1. The method described in example 8 is more effective than the method described in example 1 for recovering reactant at the surface of the first coated sheet and transferring it to another sheet. These results indicate that the two deposition methods are not equivalent. The method described in example 1 tends to make the reactant penetrate deeply into the thickness of the paper sheets whilst the method described in example 8 enables a more superficial spreading of the fatty acid chloride.
EXAMPLE 12—DISTRIBUTION TEMPERATURE
[0123] A varnish roller is loaded with fatty acid chloride in an optimal manner in accordance with example 1. Sheets continue to be coated with this roller according to the method described in example 1 or according to the method described in example 8 without reloading it but by placing the sheets at a temperature of 60° C. It is observed that the hydrophobicity of the sheets coated at 60° C. is better than that carried out at ambient temperature. These results indicate that the reactant transfer efficiency is better at higher temperature.
EXAMPLE 13—HOT DEPOSITION
[0124] A varnish roller is loaded with fatty acid chloride in an optimal manner in accordance with example 1. A tissue is placed in the oven at 160° C. so that it reaches its thermal equilibrium. Next the door of the oven is opened and the fatty acid chloride is deposited with the varnish roller directly on the hot tissue in the oven. No fog of condensation is observed during the deposition. The tissue is then removed from the oven and tested for its hydrophobicity. This is excellent with a distinct water repellency. This experiment shows that it is possible to carry out the deposition of the fatty acid chloride at high temperature corresponding to chromatogenic reaction conditions. The deposition and the reaction are virtually simultaneous. The additional advantage of this high-temperature deposition is that it makes it possible to eliminate at least one portion of the water contained in the paper, which could lead to a partial hydrolysis of the fatty acid chloride, and to carry out the acylation under substantially anhydrous conditions.
EXAMPLE 14—BEHENIC ACID CHLORIDE
[0125] Palmitic acid chloride and behenic acid chloride are used as reactant. Good results are obtained in both cases. The hydrophobicity conferred by the palmitic acid is lower, whereas that conferred by the behenic acid is excellent.
EXAMPLE 15—OLEOPHILIC VELVET ROLLER AND OLEOPHOBIC VELVET ROLLER
[0126] A comparative test of the distribution of a fatty acid chloride on a paper material is carried out: [0127] using a varnish roller formed of an oleophilic velvet according to the invention, and; [0128] using a varnish roller formed of an oleophobic velvet according to the invention in which the filiform elements are coated with Teflon®.
[0129] The varnish roller having an oleophobic velvet necessitates eliminating, prior to the deposition, an excess of fatty acid chloride distributed non-uniformly on the surface of the varnish roller, but the deposition of residual fatty acid chloride gives excellent results in terms of hydrophobicity.
EXAMPLE 16—POLYVINYL ALCOHOL (PVA)
[0130] 100 mg/m.sup.2 of stearic acid chloride is applied with a varnish roller to a sheet of paper coated with 10 g of PVA 2899 having an average molecular weight of 145 000. This sheet is placed in an oven at 150°. After one minute, the door is opened and no formation of fog of condensation is observed, which indicates that there is no significant excess of reactant. The sheet is then tested for its hydrophobicity and it proves to be perfectly water repellent.
EXAMPLE 17—COMPARATIVE TEST—FOAM ROLLER (OUTSIDE THE INVENTION)
[0131] A foam roller is loaded with 1 ml of fatty acid chloride. The loading of the foam roller is homogenized by rolling. The roller is applied to a sheet of kitchen roll. After passing through the oven at 150°, the hydrophobicity of the sheet of kitchen roll is analysed. It is observed that the hydrophobicity is irregular. The sheet of kitchen roll has hydrophobic zones and non-hydrophobic zones. The foam roller does not allow a distribution of the fatty acid chloride on the sheet of kitchen roll such that it enables an impermeabilization of the sheet of kitchen roll.
[0132] There may be numerous variants and applications of the invention other than those described above. In particular, it goes without saying that, unless indicated otherwise, the different structural and functional characteristics of each of the embodiments described above should not be considered as being combined and/or closely and/or inextricably linked with one another, but, by contrast, as being simple juxtapositions. Moreover, the structural and/or functional characteristics of the different embodiments described above may be subject in full or in part to any other juxtaposition or any other combination.