FR2920107A1 - PROCESS FOR TREATING CORK OR CORNWARE MATERIAL WITH INERT GAS UNDER PRESSURE STRICTLY LESS THAN 1 MPA - Google Patents

Abstract

Process for treating a cork or cork based material, comprises contacting the cork or the cork based material with an inert gas at a treatment temperature of 20-140[deg] C and under a pressure strictly less than 1 MPa (10 bars).

Description

B 07-1658 EN GD / IC Simplified joint stock company: OENEO BOUCHAGE

  Process for treating cork or a cork-based material with an inert gas under a pressure strictly less than 1 MPa Invention of: Rudolf Zobel and Moaad Bakali Process for treating cork or a cork-based material with an inert gas at a pressure strictly less than 1 MPa.

  The present invention relates to a method of treating cork or a cork-based material, comprising contacting the cork or the cork-based material with an inert gas at a treatment temperature of 20 to 140 ° C. and under a pressure strictly lower than 1 MPa (10 bar), a process for producing stoppers and plugs obtainable by this method. Cork is a natural, impervious and light material, which comes from the bark of some species of oaks, such as cork oaks, which are typically found in the countries around the Mediterranean, Europe and North Africa.

  Cork is particularly used in the manufacture of corks, which serve to plug containers such as bottles containing liquids for food, especially wine. Cork is an elastic material, resilient, compressible and impermeable to liquids, having at the same time a gas permeability sufficient to allow an exchange necessary for the maturation of the bottled product, and having a high coefficient of friction. Because of its natural origin, it has very different mechanical properties and permeability depending on the origin of the cork and contains sometimes unwanted organic components, their contents also vary according to the origins of the cork. Naturally occurring substances in cork can pass into drinks and develop an unpleasant taste, for example, of "rotten", making these drinks inedible.

  These substances may be organic compounds such as methyl-isoborneol, geosmin, methylthio-ethylpyrazine, C8 unsaturated alcohols and ketones; chlorinated compounds such as lindane, chlorinated or non-chlorinated phenols, chlorinated or non-chlorinated anisoles, and more particularly pentachlorophenol (PCP), 2,4,6-trichloroanisole (TCA), 2,3,4,6 tetrachloroanisole (TeCA) and pentachloroanisole, and brominated compounds such as tribromoanisole, responsible for cork or mold taste; or else p-cresol, guaiacol and octanoic acid responsible for the taste of phenol-leather-synthetic; or 1-octen-3-ol associated with mushroom taste. These substances are therefore contaminants or pollutants to be eliminated to allow the use of cork or a cork-based material for the manufacture of corks. In order, in particular, to eliminate them as much as possible, the cork or the cork-based material is generally subjected to treatments known in the art, in particular using carbon dioxide in the supercritical state. An example of treatment is described by Ana M. Miranda et al., "High Pressure Extraction of Cork with CO2 and 1,4-dioxane", Process. Technol. Proc. (1996), 12, High Pressure Chemical Engineering, p. This is a method of treating cork with CO2 and dioxane under conditions of high pressure of 170 bar and temperatures of 160 to 180 C. Suberin elimination occurs. , a component of the cell walls of cork in the form of modified lignin. However, this process is not suitable for treating cork, which must then be used as cork for bottles. It is also known from international patent application WO 01/23155, a process for the treatment and extraction of organic compounds of cork or of a material based on cork, using a dense fluid under pressure, at a temperature of 10 to 120 C and a pressure of 10 to 600 bar. However, the methods of the prior art do not make it possible to obtain a cork or a cork-based material having both good mechanical and organoleptic properties. Indeed, the cork, by its different origins, has different mechanical and organoleptic properties, that is to say includes organic compounds responsible for said properties in different contents. For example, suberin and waxes responsible for mechanical properties are not contained in the same proportions in corks of different origins. It is the same for the compounds responsible for organoleptic properties such as natural flavors.

  Moreover, the difference in mechanical properties and permeability makes random the good storage of beverages over time and therefore does not allow a perfect aging of it, and especially wine. There is therefore a need to produce cork or a cork-based material having both good mechanical and organoleptic properties. The aim of the invention is to satisfy this need by proposing a method of treating cork or a material based on cork, which makes it possible both to eliminate volatile organic compounds, in particular those responsible for cork taste, while at the same time preserving the mechanical properties of said cork or cork-based material, for example hydrophobicity. This process can be furthermore more easily implemented than the cork or cork-based processes known in the art. A first object of the present invention is therefore a process for treating cork or a cork-based material, comprising placing it in contact with an inert gas at a treatment temperature of 20 ° C. to 140 ° C. under a pressure that is strictly less than 20 ° C. 1 MPa (10 bar). Another object relates to a process for manufacturing stoppers using such a method for treating cork or a material based on cork. The invention also relates to a plug that can be obtained by the manufacturing process. According to the invention, the process for treating cork or a cork-based material comprises contacting the cork or the cork-based material with an inert gas at a treatment temperature of 20 ° C. to 140 ° C. preferably from 80 to 120 ° C., and under a pressure strictly below 1 MPa (10 bar), preferably from 0.1 to 0.4 MPa (1 to 4 bar), more preferably equal to atmospheric pressure. The cork or the cork-based material that can be used in the process of the invention is in particular in the form of granules preferably having a particle size of 0.1 mm up to 7 mm, plates, boards, cork washers from the casing of cork plates, natural corks from cork plaster casings, or cork-based corks such as 1 + 1, agglomerated or micro-agglomerated corks based on glue and agents possible expansion. The particle size can be measured for example by the sieve method, at room temperature (20-25 C). Tubing is a method of making stoppers using a punch. We take a piece of cork whose thickness corresponds to the length of the cork. By 1 + 1, we mean a stopper whose body consists of agglomerated cork granules with an adhesive, while the two ends are each composed of a natural cork washer, said washers being obtained by casing a piece of cork whose thickness corresponds to that of the washers. The inert gas that can be used in the process according to the invention is especially chosen from carbon dioxide, nitrogen, a rare gas such as argon, and their mixtures, preferably from carbon dioxide, nitrogen and their mixtures. mixtures, and even more preferably the inert gas is carbon dioxide. According to a preferred embodiment of the invention, the inert gas can be mixed with one or more so-called cosolvent compounds. This co-solvent (s) is (are) preferably chosen from water and (C 1 -C 4) alcohols, such as ethanol. Said co-solvent or a mixture thereof is preferably added at a rate of 0 until the co-solvent gas is saturated at the treatment temperature, which is in the range of from 20 ° C to 140 ° C, more preferably 0.001% by weight relative to the weight of the mixture of inert gas + co-solvent (s) until the saturation of the gas in co-solvent (s) at the treatment temperature, and still more preferably from 0.001% by weight to 10 % by weight relative to the mixture of inert gas and co-solvent (s).

  According to another embodiment, the cork or the cork-based material can be moistened by spraying water before being treated with the inert gas stream, in proportions ranging from 5% to 40%, more preferably from 15% to 25% by weight relative to the total weight of the cork.

  The duration of treatment generally ranges from 1 to 10 hours, more preferably from 2 to 4 hours. The process according to the invention can be carried out continuously or discontinuously, in a fixed bed or fluidized bed reactor. The process according to the invention carried out continuously may further comprise a step of recycling the inert gas, optionally mixed with at least one co-solvent, comprising the organic compounds extracted from cork or cork-based material, in the reactor after being subjected to a purification step, for example using activated charcoal or an absorbent substance such as bentonite, in order to eliminate the volatile organic compounds separated from the cork or the cork material, and the cosolvent (s) of the inert gas. In order to improve the efficiency of the absorption of the organic products in the purification step, at least one exchanger may be used in order to reduce the temperature to a value of less than 40 ° C., preferably of between 15 ° C. and 25 ° C. separation between the gas optionally mixed with at least one co-solvent, and the extracted organic products can also be achieved by the addition of one or more cyclone type separators.

  Another object of the invention is the use of the method according to the invention for extracting volatile organic compounds. Volatile organic compounds are hydrocarbons (compounds consisting of carbon atoms and hydrogen), excluding methane, in which one or more of the hydrogen atoms may be substituted by halogen atoms as chlorine or fluorine, oxygen, nitrogen, sulfur or phosphorus groups having a vapor pressure greater than or equal to 133 Pa at a temperature of 293.15 K. Volatile organic compounds are generally in the form of a gas or steam under normal conditions of temperature and pressure. Their Henry constant (Kh) is preferably greater than or equal to 100 Pa.m3 / mol. The volatile organic compounds extracted with the process of the invention are especially (poly) chlorophenols such as pentachlorophenol (PCP), and (poly) haloanisoles such as (poly) chloroanisoles, for example 2,4,6-trichloroanisole ( TCA), 2,3,4,6-tetrachloroanisole (TeCA) and pentachloroanisole, and tribromoanisole, responsible for cork or mold taste; or p-cresol, guaiacol and octanoic acid, responsible for the taste of phenol-leather-synthetic; or 1-octen-3-ol associated with mushroom taste. A preferred embodiment of the use of the process is to extract (poly) chlorophenols such as pentachlorophenol (PCP), and (poly) haloanisoles such as (poly) chloroanisoles, for example 2,4,6-trichloroanisole ( TCA), 2,3,4,6-tetrachloroanisole (TeCA) and pentachloroanisole, and tribromoanisole. The invention further relates to a method for manufacturing corks or a cork-based material, comprising the method of treating cork or cork-based material as described above. Some preferred embodiments of the invention will now be described by way of nonlimiting examples, with reference to the examples and the appended drawings, in which: FIG. 1 is a schematic view of a device implementing a treatment method according to the invention, and - Figure 2 is a schematic view of a variant of the device of Figure 1.

  In Figure 1, the reactor (1) of the device is filled with cork granules (2) having a particle size ranging from 0.1 mm to 7 mm and a density ranging from 45 to 80 g / 1. The reactor (1) has at least one of its ends, at least one filtering means such as a metal filter plate, and preferably at its two lower and upper ends (3 ') and (3 "). The insulated reactor (1) is heated with electric heating means or temperature control unit (UCT) and maintained at a constant temperature of 20 to 140 ° C, preferably 80 to 120 ° C. With the aid of an electrical resistance or a heat transfer fluid, the pressure in the reactor (1) is strictly less than 1 MPa (10 bar), preferably ranging from 0.1 to 0.4 MPa (1 to 4 bars), better still equal to the atmospheric pressure, this pressure is generally regulated by a vent located on the upper part of the reactor (1) and by regulating the flow rate of the inert gas optionally mixed with at least one co-solvent. inert, for example carbon dioxide or nitrogen or mixtures thereof from a storage tank (4) is introduced via an opening valve (5), a flow control valve (6) and a a flowmeter (7). The flow rate of the inert gas preferably varies from 50 to 150 liters / minute, more preferably from 65 to 85 liters / minute. The inert gas is used to prevent oxidation in cork, which usually occurs when air or any other oxygen-containing mixture is used that generates Maillard reactions that produce roasted tastes. burned with cork. The inert gas is then heated with electric heating means (8) to the treatment temperature of 20 to 140 ° C, preferably 80 to 120 ° C, and optionally pressurized to a pressure below 1 MPa (10 bar), preferably ranging from 0.1 to 0.4 MPa (1 to 4 bar). Preferably, the inert gas is left at atmospheric pressure.

  The inert gas is mixed, for example by bubbling, before arriving in the reactor (1), with a co-solvent (9) such as water, a C1-C4 alcohol, for example ethanol , or a mixture thereof. The addition of a co-solvent (9) such as water may, for example, make it possible to prevent the cork granules (2) from drying out during the extraction of the volatile organic compounds, while improving the rate extraction. The inert gas + co-solvent mixture is further passed through an electrical heating means (10), which improves the solubility of the co-solvent in the gas, to reach a constant temperature in the range of 20 to 140 C, preferably 80 to 120 C. The pressure of the inert gas mixture + co-solvent is adjusted via the vent (12) of the reactor to reach a pressure of less than 1 MPa (10 bar), preferably of 0 , 1 to 0.4 MPa (1 to 4 bar). Preferably, said mixture is left at atmospheric pressure. The device of FIG. 1 further comprises an electronic control unit (11) which manages the operation of the elements (5), (6), (7), (8), (10) and (12). When the inert gas is used alone, ie without co-solvent, the device of FIG. 1 does not include elements (9) and (10). The process according to the invention, passing a stream of inert gas optionally mixed with a co-solvent, through the cork granules (2) in the reactor (1) lasts several hours, preferably from 1 to 10 hours, better still 2 to 4 hours. The inert gas, optionally mixed with a co-solvent, passes through the cork granules (2) in a fixed bed or in a fluidized bed. The inert gas, optionally mixed with a co-solvent, makes it possible to extract undesirable volatile organic compounds, such as (poly) chlorophenols such as pentachlorophenol (PCP); (poly) haloanisoles such as (poly) chloroanisoles, for example 2,4,6-trichloroanisole (TCA), 2,3,4,6-tetrachloroanisole (TeCA) and pentachloroanisole, and tribromoanisole; p-cresol, guaiacol, octanoic acid and 1-octen-3-ol, out of the cork granules and entrains these volatile organic compounds out of the reactor (1).

  A vent (12) placed at the outlet of the reactor (1) makes it possible to regulate the pressure of the gas in the said reactor (1). In the device of Figure 1, the inert gas mixed with cosolvent, and containing the volatile organic compounds extracted from the granules, is not recycled but released into the atmosphere. According to another embodiment of the invention shown in FIG. 2, the device comprises the same elements (1) to (12) as the device of FIG. 1. However, at the outlet of the reactor (1), the inert gas mixed with a co-solvent, loaded with volatile organic compounds extracted from the cork granules, is recycled after being passed through a cooling system (13), a separator (14) and a purification device (16) consisting, for example, of an activated carbon or bentonite column. The electronic control unit (11) of FIG. 2 also manages the operation of the elements (13) and (15), in addition to that of the elements (5), (6), (7), (8), (10) and (12). At the outlet of the reactor (1) and before passing through the purification device (16), it is important that the temperature of the mixture of inert gas + co-solvent charged with volatile organic compounds extracted is reduced to a value of less than 40 C, preferably between 15 ° C. and 25 ° C., in particular using the cooling system (13). After this cooling step, the inert gas + co-solvent mixture charged with volatile organic compounds passes through a cyclone separating device (14) which makes a first separation between the inert gas, the co-solvent and the volatile organic compounds. The valve (15) draws a majority or total amount of volatile organic compounds, and a portion of the co-solvent. The purification device (16) completes the purification of the inert gas by absorbing any residual volatile organic compounds and the residual cosolvent. The combination of the elements (14) and (16) makes it possible to obtain a very good extraction rate, for example of the order of 100%, of the volatile organic compounds, and of completely purifying the inert gas, before the reintroduce into the extraction circuit.

  Other separating devices, for example of the cyclone type, can still be introduced into the device of FIG. 2. The device of FIG. 2 also comprises a recirculation fan (17) which recycles the inert gas in the extraction circuit.

  EXAMPLES Various samples of cork granules were subjected to the treatment method of the invention. The content of 2,4,6-trichloroanisole contained in the cork granules was measured before and after treatment with the process according to the invention. It was measured by the method defined in the standard AFNOR ISO 20752: 2007 (F), edition of February 2007, called cork stoppers at the 2,4,6-trichloroanisol (TCA) release rate. The limits of detection and quantification are respectively 0.2 and 0.5 ng / l.

  Example 1 A fluidized bed reactor having a volume of about 8 liters was used. The reactor (1) was filled with the device of FIG. 1 which does not include elements (9) and (10), with 104 g. of cork granules (average particle size of about 1 mm), representing 18% of the volume of the reactor (1), and closed with flat filters (3 ') and (3 "). treated the cork granules with a stream of dry carbon dioxide gas without co-solvent, circulating at a flow rate of 75 l / min., at a temperature of 95.5 C for 5 hours, at atmospheric pressure. At the end of this treatment, the pellets were allowed to cool always in the presence of carbon dioxide for 45 minutes and then brought back into contact with the air.

  The results for TCA levels are summarized in Table 1 below.

  Table 1 TCA content (ng / l) Before treatment 3.0 After treatment 0.9 A 70% reduction in the content of 2,4,6-trichloroanisole present in the treated cork granules is observed.

  Example 2 A fluidized bed reactor having a volume of about 8 liters was used. The reactor (1) was filled with the device of FIG. 1 with 15 100 g. of cork granules and closed with flat filters (3 ') and (3 ") The cork granules were treated with a flow of carbon dioxide gas flowing at a flow rate of 75 1 It is then mixed with 0.8 liter of water, at a temperature of 100 ° C. for 5 hours, at atmospheric pressure, at the end of which the granules are allowed to warm to room temperature as in Example 1, for 45 minutes, and then brought back into contact with the air The TCA results are summarized in Table 2 below.5 Table 2 TCA Content (ng / 1) Before treatment 6.1 After treatment 0.5

  There is a 92% reduction in the 2,4,26-trichloroanisole content present in treated cork granules.

  Example 3 A fixed bed reactor having a volume of about 8 liters was used. The reactor (1) was filled with the device of FIG. 1 with 600 g. cork granules and closed with flat filters (3 ') and (3 ") The granules were treated with a flow of circulating carbon dioxide gas at a flow rate of 75 1 / min, and mixed with 1.2 liters of water, at a temperature of 98.5 C for 6 hours, under atmospheric pressure, the carbon dioxide having been in contact with demineralized water before the treatment of the granules of water. At the end of this treatment, the granules were allowed to come back to room temperature as in Example 1 for 45 minutes and then brought back into contact with the air. grouped in Table 3 below.

  Table 3 TCA Content (ng / 1) Before Treatment 5.9 After Treatment 0.4

  There is therefore a 90% reduction in 2,4,6-trichloroanisole content in treated cork granules.

  Example 4 A fluidized bed reactor having a volume of about 8 liters was used. 100 g were treated. of cork granules with about 20 g. of water. The reactor (1) was then filled with the device of FIG. 1, which does not include the elements (9) and (10), with these 100 g. wet cork granules.

  The granules were treated with a stream of dry carbon dioxide gas without a co-solvent, circulating at a rate of 75 l / min., At a temperature of 97.5 C for 4 hours, at atmospheric pressure. At the end of this treatment, the granules were allowed to warm to room temperature as in Example 1 for 45 minutes and then re-contacted with air. The results for TCA levels are summarized in Table 4 below.

  Table 4 TCA content (ng / l) Before treatment 5.9 After treatment 0.8 An 86% reduction in the content of 2,4,6-trichloroanisole present in the treated cork granules was observed.

  Example 5 A fluidized bed reactor having a volume of about 8 liters was used. The reactor (1) was filled with the device of FIG. 1 with 100 g. of cork granules and closed with flat filters (3 ') and (3 ") The cork granules were treated with a flow of carbon dioxide gas flowing at a flow rate of 75 1 and mixed with 0.8 liter of a 50/50 mixture by weight of deionized water and ethanol at a temperature of 98.5 C for 4 hours at atmospheric pressure. After this treatment, the granules were allowed to come back to room temperature as in Example 1 for 45 minutes and then brought back into contact with the air.The results concerning the TCA contents are summarized in Table 5 below. -Dessous.

  Table 5 TCA Content (ng / l) Before Treatment 5.9 After Treatment Undetectable A reduction of 100% in the 2,4,6-trichloroanisole content in the treated cork granules is observed.

  Example 6 A fluidized bed reactor having a volume of about 8 liters was used. The reactor (1) was filled with the device of FIG. 1 with 100 g. cork granules and closed with flat filters (3 ') and (3 ") The granules were treated with a flowing stream of nitrogen at a rate of 75 l / min. and mixed with 0.8 liter of water, at a temperature of 100 C for 4 hours, at atmospheric pressure.

  At the end of this treatment, the granules were allowed to warm to room temperature in the presence of nitrogen. The results for TCA levels are summarized in Table 6 below.

  Table 6 TCA Content (ng / 1) Before Treatment 5.9 After Treatment 0.4

  There is a 93% reduction in the 2,4,6-trichloroanisole content present in the treated cork granules. 20

  Example 7 The procedure was the same as in Example 2, except that the treatment time was 4 hours instead of 5 hours. The results for TCA levels are summarized in Table 7 below.

  Table 7 TCA Content (ng / 1) Before Treatment 5.9 After Treatment 0.4

  There is a 93% reduction in the 2,4,6-5 trichloroanisole content present in treated cork granules.

Claims (14)

  A method for the treatment of cork or a cork-based material, comprising contacting the cork or the cork-based material with an inert gas at a treatment temperature of 20 to 140 C and under a pressure strictly less than 1 MPa (10 bar).   2. Process for treating cork or a cork-based material according to claim 1, characterized in that the inert gas is chosen from carbon dioxide, nitrogen, an inert rare gas such as argon, and their mixtures.   3. Process for treating cork or a cork-based material according to claim 1 or 2, characterized in that the treatment temperature is from 80 to 120 ° C.   4. Process for treating cork or a cork-based material according to one of the preceding claims, characterized in that the pressure is in the range of 0.1 to 0.4 MPa (1 to 4 bars).   5. Process for treating cork or a cork-based material according to claim 4, characterized in that the pressure is equal to atmospheric pressure.   6. Process for treating cork or a cork-based material according to any one of the preceding claims, characterized in that the inert gas is mixed with one or more co-solvents.   7. Process for treating cork or a cork-based material according to claim 6, characterized in that the co-solvent (s) is or are chosen from water and alcohols. C1_4 such as ethanol.   8. Process for treating cork or a cork-based material according to claim 6 or 7, characterized in that the cosolvent (s) is (are) present in a content ranging from 0.001% to weight relative to the total weight of the mixture of inert gas + co-solvent (s) until the saturation of the gas in co-solvent (s) at the treatment temperature.   Process for treating cork or a cork-based material according to one of the preceding claims, characterized in that the cork or the cork-based material is in the form of granules, slabs, planks, washers or plugs natural or technical.   10. Process for treating cork or a cork-based material according to claim 9, characterized in that the granules have a particle size ranging from 0.1 to 7 mm.   11. Use of the method according to any one of the preceding claims, for extracting volatile organic compounds. 25   12. Use according to claim 11, characterized in that the volatile organic compounds are chosen from (poly) chlorophenols, (poly) haloanisoles, p-cresol, guaiacol and octanoic acid and 1-octen-3. ol. 30   13. Use according to claim 12, characterized in that the volatile organic compounds are chosen from pentachlorophenol, 2,4,6-trichloroanisole, 2,3,4,6-tetrachloroanisole, pentachloroanisole and tribromoanisole.   Process for the production of cork or cork-based stoppers comprising the cork or cork-based treatment method according to one of claims 1 to 10.5.